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llvm-6502/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
Dan Gohman 5686752099 Simplify some getNode calls. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@52604 91177308-0d34-0410-b5e6-96231b3b80d8
2008-06-21 22:06:07 +00:00

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//===-- DAGCombiner.cpp - Implement a DAG node combiner -------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass combines dag nodes to form fewer, simpler DAG nodes. It can be run
// both before and after the DAG is legalized.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "dagcombine"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include <algorithm>
#include <set>
using namespace llvm;
STATISTIC(NodesCombined , "Number of dag nodes combined");
STATISTIC(PreIndexedNodes , "Number of pre-indexed nodes created");
STATISTIC(PostIndexedNodes, "Number of post-indexed nodes created");
namespace {
#ifndef NDEBUG
static cl::opt<bool>
ViewDAGCombine1("view-dag-combine1-dags", cl::Hidden,
cl::desc("Pop up a window to show dags before the first "
"dag combine pass"));
static cl::opt<bool>
ViewDAGCombine2("view-dag-combine2-dags", cl::Hidden,
cl::desc("Pop up a window to show dags before the second "
"dag combine pass"));
#else
static const bool ViewDAGCombine1 = false;
static const bool ViewDAGCombine2 = false;
#endif
static cl::opt<bool>
CombinerAA("combiner-alias-analysis", cl::Hidden,
cl::desc("Turn on alias analysis during testing"));
static cl::opt<bool>
CombinerGlobalAA("combiner-global-alias-analysis", cl::Hidden,
cl::desc("Include global information in alias analysis"));
//------------------------------ DAGCombiner ---------------------------------//
class VISIBILITY_HIDDEN DAGCombiner {
SelectionDAG &DAG;
TargetLowering &TLI;
bool AfterLegalize;
// Worklist of all of the nodes that need to be simplified.
std::vector<SDNode*> WorkList;
// AA - Used for DAG load/store alias analysis.
AliasAnalysis &AA;
/// AddUsersToWorkList - When an instruction is simplified, add all users of
/// the instruction to the work lists because they might get more simplified
/// now.
///
void AddUsersToWorkList(SDNode *N) {
for (SDNode::use_iterator UI = N->use_begin(), UE = N->use_end();
UI != UE; ++UI)
AddToWorkList(UI->getUser());
}
/// visit - call the node-specific routine that knows how to fold each
/// particular type of node.
SDOperand visit(SDNode *N);
public:
/// AddToWorkList - Add to the work list making sure it's instance is at the
/// the back (next to be processed.)
void AddToWorkList(SDNode *N) {
removeFromWorkList(N);
WorkList.push_back(N);
}
/// removeFromWorkList - remove all instances of N from the worklist.
///
void removeFromWorkList(SDNode *N) {
WorkList.erase(std::remove(WorkList.begin(), WorkList.end(), N),
WorkList.end());
}
SDOperand CombineTo(SDNode *N, const SDOperand *To, unsigned NumTo,
bool AddTo = true);
SDOperand CombineTo(SDNode *N, SDOperand Res, bool AddTo = true) {
return CombineTo(N, &Res, 1, AddTo);
}
SDOperand CombineTo(SDNode *N, SDOperand Res0, SDOperand Res1,
bool AddTo = true) {
SDOperand To[] = { Res0, Res1 };
return CombineTo(N, To, 2, AddTo);
}
private:
/// SimplifyDemandedBits - Check the specified integer node value to see if
/// it can be simplified or if things it uses can be simplified by bit
/// propagation. If so, return true.
bool SimplifyDemandedBits(SDOperand Op) {
APInt Demanded = APInt::getAllOnesValue(Op.getValueSizeInBits());
return SimplifyDemandedBits(Op, Demanded);
}
bool SimplifyDemandedBits(SDOperand Op, const APInt &Demanded);
bool CombineToPreIndexedLoadStore(SDNode *N);
bool CombineToPostIndexedLoadStore(SDNode *N);
/// combine - call the node-specific routine that knows how to fold each
/// particular type of node. If that doesn't do anything, try the
/// target-specific DAG combines.
SDOperand combine(SDNode *N);
// Visitation implementation - Implement dag node combining for different
// node types. The semantics are as follows:
// Return Value:
// SDOperand.Val == 0 - No change was made
// SDOperand.Val == N - N was replaced, is dead, and is already handled.
// otherwise - N should be replaced by the returned Operand.
//
SDOperand visitTokenFactor(SDNode *N);
SDOperand visitMERGE_VALUES(SDNode *N);
SDOperand visitADD(SDNode *N);
SDOperand visitSUB(SDNode *N);
SDOperand visitADDC(SDNode *N);
SDOperand visitADDE(SDNode *N);
SDOperand visitMUL(SDNode *N);
SDOperand visitSDIV(SDNode *N);
SDOperand visitUDIV(SDNode *N);
SDOperand visitSREM(SDNode *N);
SDOperand visitUREM(SDNode *N);
SDOperand visitMULHU(SDNode *N);
SDOperand visitMULHS(SDNode *N);
SDOperand visitSMUL_LOHI(SDNode *N);
SDOperand visitUMUL_LOHI(SDNode *N);
SDOperand visitSDIVREM(SDNode *N);
SDOperand visitUDIVREM(SDNode *N);
SDOperand visitAND(SDNode *N);
SDOperand visitOR(SDNode *N);
SDOperand visitXOR(SDNode *N);
SDOperand SimplifyVBinOp(SDNode *N);
SDOperand visitSHL(SDNode *N);
SDOperand visitSRA(SDNode *N);
SDOperand visitSRL(SDNode *N);
SDOperand visitCTLZ(SDNode *N);
SDOperand visitCTTZ(SDNode *N);
SDOperand visitCTPOP(SDNode *N);
SDOperand visitSELECT(SDNode *N);
SDOperand visitSELECT_CC(SDNode *N);
SDOperand visitSETCC(SDNode *N);
SDOperand visitSIGN_EXTEND(SDNode *N);
SDOperand visitZERO_EXTEND(SDNode *N);
SDOperand visitANY_EXTEND(SDNode *N);
SDOperand visitSIGN_EXTEND_INREG(SDNode *N);
SDOperand visitTRUNCATE(SDNode *N);
SDOperand visitBIT_CONVERT(SDNode *N);
SDOperand visitBUILD_PAIR(SDNode *N);
SDOperand visitFADD(SDNode *N);
SDOperand visitFSUB(SDNode *N);
SDOperand visitFMUL(SDNode *N);
SDOperand visitFDIV(SDNode *N);
SDOperand visitFREM(SDNode *N);
SDOperand visitFCOPYSIGN(SDNode *N);
SDOperand visitSINT_TO_FP(SDNode *N);
SDOperand visitUINT_TO_FP(SDNode *N);
SDOperand visitFP_TO_SINT(SDNode *N);
SDOperand visitFP_TO_UINT(SDNode *N);
SDOperand visitFP_ROUND(SDNode *N);
SDOperand visitFP_ROUND_INREG(SDNode *N);
SDOperand visitFP_EXTEND(SDNode *N);
SDOperand visitFNEG(SDNode *N);
SDOperand visitFABS(SDNode *N);
SDOperand visitBRCOND(SDNode *N);
SDOperand visitBR_CC(SDNode *N);
SDOperand visitLOAD(SDNode *N);
SDOperand visitSTORE(SDNode *N);
SDOperand visitINSERT_VECTOR_ELT(SDNode *N);
SDOperand visitEXTRACT_VECTOR_ELT(SDNode *N);
SDOperand visitBUILD_VECTOR(SDNode *N);
SDOperand visitCONCAT_VECTORS(SDNode *N);
SDOperand visitVECTOR_SHUFFLE(SDNode *N);
SDOperand XformToShuffleWithZero(SDNode *N);
SDOperand ReassociateOps(unsigned Opc, SDOperand LHS, SDOperand RHS);
SDOperand visitShiftByConstant(SDNode *N, unsigned Amt);
bool SimplifySelectOps(SDNode *SELECT, SDOperand LHS, SDOperand RHS);
SDOperand SimplifyBinOpWithSameOpcodeHands(SDNode *N);
SDOperand SimplifySelect(SDOperand N0, SDOperand N1, SDOperand N2);
SDOperand SimplifySelectCC(SDOperand N0, SDOperand N1, SDOperand N2,
SDOperand N3, ISD::CondCode CC,
bool NotExtCompare = false);
SDOperand SimplifySetCC(MVT VT, SDOperand N0, SDOperand N1,
ISD::CondCode Cond, bool foldBooleans = true);
SDOperand SimplifyNodeWithTwoResults(SDNode *N, unsigned LoOp,
unsigned HiOp);
SDOperand CombineConsecutiveLoads(SDNode *N, MVT VT);
SDOperand ConstantFoldBIT_CONVERTofBUILD_VECTOR(SDNode *, MVT);
SDOperand BuildSDIV(SDNode *N);
SDOperand BuildUDIV(SDNode *N);
SDNode *MatchRotate(SDOperand LHS, SDOperand RHS);
SDOperand ReduceLoadWidth(SDNode *N);
SDOperand GetDemandedBits(SDOperand V, const APInt &Mask);
/// GatherAllAliases - Walk up chain skipping non-aliasing memory nodes,
/// looking for aliasing nodes and adding them to the Aliases vector.
void GatherAllAliases(SDNode *N, SDOperand OriginalChain,
SmallVector<SDOperand, 8> &Aliases);
/// isAlias - Return true if there is any possibility that the two addresses
/// overlap.
bool isAlias(SDOperand Ptr1, int64_t Size1,
const Value *SrcValue1, int SrcValueOffset1,
SDOperand Ptr2, int64_t Size2,
const Value *SrcValue2, int SrcValueOffset2);
/// FindAliasInfo - Extracts the relevant alias information from the memory
/// node. Returns true if the operand was a load.
bool FindAliasInfo(SDNode *N,
SDOperand &Ptr, int64_t &Size,
const Value *&SrcValue, int &SrcValueOffset);
/// FindBetterChain - Walk up chain skipping non-aliasing memory nodes,
/// looking for a better chain (aliasing node.)
SDOperand FindBetterChain(SDNode *N, SDOperand Chain);
public:
DAGCombiner(SelectionDAG &D, AliasAnalysis &A)
: DAG(D),
TLI(D.getTargetLoweringInfo()),
AfterLegalize(false),
AA(A) {}
/// Run - runs the dag combiner on all nodes in the work list
void Run(bool RunningAfterLegalize);
};
}
namespace {
/// WorkListRemover - This class is a DAGUpdateListener that removes any deleted
/// nodes from the worklist.
class VISIBILITY_HIDDEN WorkListRemover :
public SelectionDAG::DAGUpdateListener {
DAGCombiner &DC;
public:
explicit WorkListRemover(DAGCombiner &dc) : DC(dc) {}
virtual void NodeDeleted(SDNode *N, SDNode *E) {
DC.removeFromWorkList(N);
}
virtual void NodeUpdated(SDNode *N) {
// Ignore updates.
}
};
}
//===----------------------------------------------------------------------===//
// TargetLowering::DAGCombinerInfo implementation
//===----------------------------------------------------------------------===//
void TargetLowering::DAGCombinerInfo::AddToWorklist(SDNode *N) {
((DAGCombiner*)DC)->AddToWorkList(N);
}
SDOperand TargetLowering::DAGCombinerInfo::
CombineTo(SDNode *N, const std::vector<SDOperand> &To) {
return ((DAGCombiner*)DC)->CombineTo(N, &To[0], To.size());
}
SDOperand TargetLowering::DAGCombinerInfo::
CombineTo(SDNode *N, SDOperand Res) {
return ((DAGCombiner*)DC)->CombineTo(N, Res);
}
SDOperand TargetLowering::DAGCombinerInfo::
CombineTo(SDNode *N, SDOperand Res0, SDOperand Res1) {
return ((DAGCombiner*)DC)->CombineTo(N, Res0, Res1);
}
//===----------------------------------------------------------------------===//
// Helper Functions
//===----------------------------------------------------------------------===//
/// isNegatibleForFree - Return 1 if we can compute the negated form of the
/// specified expression for the same cost as the expression itself, or 2 if we
/// can compute the negated form more cheaply than the expression itself.
static char isNegatibleForFree(SDOperand Op, bool AfterLegalize,
unsigned Depth = 0) {
// No compile time optimizations on this type.
if (Op.getValueType() == MVT::ppcf128)
return 0;
// fneg is removable even if it has multiple uses.
if (Op.getOpcode() == ISD::FNEG) return 2;
// Don't allow anything with multiple uses.
if (!Op.hasOneUse()) return 0;
// Don't recurse exponentially.
if (Depth > 6) return 0;
switch (Op.getOpcode()) {
default: return false;
case ISD::ConstantFP:
// Don't invert constant FP values after legalize. The negated constant
// isn't necessarily legal.
return AfterLegalize ? 0 : 1;
case ISD::FADD:
// FIXME: determine better conditions for this xform.
if (!UnsafeFPMath) return 0;
// -(A+B) -> -A - B
if (char V = isNegatibleForFree(Op.getOperand(0), AfterLegalize, Depth+1))
return V;
// -(A+B) -> -B - A
return isNegatibleForFree(Op.getOperand(1), AfterLegalize, Depth+1);
case ISD::FSUB:
// We can't turn -(A-B) into B-A when we honor signed zeros.
if (!UnsafeFPMath) return 0;
// -(A-B) -> B-A
return 1;
case ISD::FMUL:
case ISD::FDIV:
if (HonorSignDependentRoundingFPMath()) return 0;
// -(X*Y) -> (-X * Y) or (X*-Y)
if (char V = isNegatibleForFree(Op.getOperand(0), AfterLegalize, Depth+1))
return V;
return isNegatibleForFree(Op.getOperand(1), AfterLegalize, Depth+1);
case ISD::FP_EXTEND:
case ISD::FP_ROUND:
case ISD::FSIN:
return isNegatibleForFree(Op.getOperand(0), AfterLegalize, Depth+1);
}
}
/// GetNegatedExpression - If isNegatibleForFree returns true, this function
/// returns the newly negated expression.
static SDOperand GetNegatedExpression(SDOperand Op, SelectionDAG &DAG,
bool AfterLegalize, unsigned Depth = 0) {
// fneg is removable even if it has multiple uses.
if (Op.getOpcode() == ISD::FNEG) return Op.getOperand(0);
// Don't allow anything with multiple uses.
assert(Op.hasOneUse() && "Unknown reuse!");
assert(Depth <= 6 && "GetNegatedExpression doesn't match isNegatibleForFree");
switch (Op.getOpcode()) {
default: assert(0 && "Unknown code");
case ISD::ConstantFP: {
APFloat V = cast<ConstantFPSDNode>(Op)->getValueAPF();
V.changeSign();
return DAG.getConstantFP(V, Op.getValueType());
}
case ISD::FADD:
// FIXME: determine better conditions for this xform.
assert(UnsafeFPMath);
// -(A+B) -> -A - B
if (isNegatibleForFree(Op.getOperand(0), AfterLegalize, Depth+1))
return DAG.getNode(ISD::FSUB, Op.getValueType(),
GetNegatedExpression(Op.getOperand(0), DAG,
AfterLegalize, Depth+1),
Op.getOperand(1));
// -(A+B) -> -B - A
return DAG.getNode(ISD::FSUB, Op.getValueType(),
GetNegatedExpression(Op.getOperand(1), DAG,
AfterLegalize, Depth+1),
Op.getOperand(0));
case ISD::FSUB:
// We can't turn -(A-B) into B-A when we honor signed zeros.
assert(UnsafeFPMath);
// -(0-B) -> B
if (ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(Op.getOperand(0)))
if (N0CFP->getValueAPF().isZero())
return Op.getOperand(1);
// -(A-B) -> B-A
return DAG.getNode(ISD::FSUB, Op.getValueType(), Op.getOperand(1),
Op.getOperand(0));
case ISD::FMUL:
case ISD::FDIV:
assert(!HonorSignDependentRoundingFPMath());
// -(X*Y) -> -X * Y
if (isNegatibleForFree(Op.getOperand(0), AfterLegalize, Depth+1))
return DAG.getNode(Op.getOpcode(), Op.getValueType(),
GetNegatedExpression(Op.getOperand(0), DAG,
AfterLegalize, Depth+1),
Op.getOperand(1));
// -(X*Y) -> X * -Y
return DAG.getNode(Op.getOpcode(), Op.getValueType(),
Op.getOperand(0),
GetNegatedExpression(Op.getOperand(1), DAG,
AfterLegalize, Depth+1));
case ISD::FP_EXTEND:
case ISD::FSIN:
return DAG.getNode(Op.getOpcode(), Op.getValueType(),
GetNegatedExpression(Op.getOperand(0), DAG,
AfterLegalize, Depth+1));
case ISD::FP_ROUND:
return DAG.getNode(ISD::FP_ROUND, Op.getValueType(),
GetNegatedExpression(Op.getOperand(0), DAG,
AfterLegalize, Depth+1),
Op.getOperand(1));
}
}
// isSetCCEquivalent - Return true if this node is a setcc, or is a select_cc
// that selects between the values 1 and 0, making it equivalent to a setcc.
// Also, set the incoming LHS, RHS, and CC references to the appropriate
// nodes based on the type of node we are checking. This simplifies life a
// bit for the callers.
static bool isSetCCEquivalent(SDOperand N, SDOperand &LHS, SDOperand &RHS,
SDOperand &CC) {
if (N.getOpcode() == ISD::SETCC) {
LHS = N.getOperand(0);
RHS = N.getOperand(1);
CC = N.getOperand(2);
return true;
}
if (N.getOpcode() == ISD::SELECT_CC &&
N.getOperand(2).getOpcode() == ISD::Constant &&
N.getOperand(3).getOpcode() == ISD::Constant &&
cast<ConstantSDNode>(N.getOperand(2))->getAPIntValue() == 1 &&
cast<ConstantSDNode>(N.getOperand(3))->isNullValue()) {
LHS = N.getOperand(0);
RHS = N.getOperand(1);
CC = N.getOperand(4);
return true;
}
return false;
}
// isOneUseSetCC - Return true if this is a SetCC-equivalent operation with only
// one use. If this is true, it allows the users to invert the operation for
// free when it is profitable to do so.
static bool isOneUseSetCC(SDOperand N) {
SDOperand N0, N1, N2;
if (isSetCCEquivalent(N, N0, N1, N2) && N.Val->hasOneUse())
return true;
return false;
}
SDOperand DAGCombiner::ReassociateOps(unsigned Opc, SDOperand N0, SDOperand N1){
MVT VT = N0.getValueType();
// reassoc. (op (op x, c1), y) -> (op (op x, y), c1) iff x+c1 has one use
// reassoc. (op (op x, c1), c2) -> (op x, (op c1, c2))
if (N0.getOpcode() == Opc && isa<ConstantSDNode>(N0.getOperand(1))) {
if (isa<ConstantSDNode>(N1)) {
SDOperand OpNode = DAG.getNode(Opc, VT, N0.getOperand(1), N1);
AddToWorkList(OpNode.Val);
return DAG.getNode(Opc, VT, OpNode, N0.getOperand(0));
} else if (N0.hasOneUse()) {
SDOperand OpNode = DAG.getNode(Opc, VT, N0.getOperand(0), N1);
AddToWorkList(OpNode.Val);
return DAG.getNode(Opc, VT, OpNode, N0.getOperand(1));
}
}
// reassoc. (op y, (op x, c1)) -> (op (op x, y), c1) iff x+c1 has one use
// reassoc. (op c2, (op x, c1)) -> (op x, (op c1, c2))
if (N1.getOpcode() == Opc && isa<ConstantSDNode>(N1.getOperand(1))) {
if (isa<ConstantSDNode>(N0)) {
SDOperand OpNode = DAG.getNode(Opc, VT, N1.getOperand(1), N0);
AddToWorkList(OpNode.Val);
return DAG.getNode(Opc, VT, OpNode, N1.getOperand(0));
} else if (N1.hasOneUse()) {
SDOperand OpNode = DAG.getNode(Opc, VT, N1.getOperand(0), N0);
AddToWorkList(OpNode.Val);
return DAG.getNode(Opc, VT, OpNode, N1.getOperand(1));
}
}
return SDOperand();
}
SDOperand DAGCombiner::CombineTo(SDNode *N, const SDOperand *To, unsigned NumTo,
bool AddTo) {
assert(N->getNumValues() == NumTo && "Broken CombineTo call!");
++NodesCombined;
DOUT << "\nReplacing.1 "; DEBUG(N->dump(&DAG));
DOUT << "\nWith: "; DEBUG(To[0].Val->dump(&DAG));
DOUT << " and " << NumTo-1 << " other values\n";
WorkListRemover DeadNodes(*this);
DAG.ReplaceAllUsesWith(N, To, &DeadNodes);
if (AddTo) {
// Push the new nodes and any users onto the worklist
for (unsigned i = 0, e = NumTo; i != e; ++i) {
AddToWorkList(To[i].Val);
AddUsersToWorkList(To[i].Val);
}
}
// Nodes can be reintroduced into the worklist. Make sure we do not
// process a node that has been replaced.
removeFromWorkList(N);
// Finally, since the node is now dead, remove it from the graph.
DAG.DeleteNode(N);
return SDOperand(N, 0);
}
/// SimplifyDemandedBits - Check the specified integer node value to see if
/// it can be simplified or if things it uses can be simplified by bit
/// propagation. If so, return true.
bool DAGCombiner::SimplifyDemandedBits(SDOperand Op, const APInt &Demanded) {
TargetLowering::TargetLoweringOpt TLO(DAG, AfterLegalize);
APInt KnownZero, KnownOne;
if (!TLI.SimplifyDemandedBits(Op, Demanded, KnownZero, KnownOne, TLO))
return false;
// Revisit the node.
AddToWorkList(Op.Val);
// Replace the old value with the new one.
++NodesCombined;
DOUT << "\nReplacing.2 "; DEBUG(TLO.Old.Val->dump(&DAG));
DOUT << "\nWith: "; DEBUG(TLO.New.Val->dump(&DAG));
DOUT << '\n';
// Replace all uses. If any nodes become isomorphic to other nodes and
// are deleted, make sure to remove them from our worklist.
WorkListRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(TLO.Old, TLO.New, &DeadNodes);
// Push the new node and any (possibly new) users onto the worklist.
AddToWorkList(TLO.New.Val);
AddUsersToWorkList(TLO.New.Val);
// Finally, if the node is now dead, remove it from the graph. The node
// may not be dead if the replacement process recursively simplified to
// something else needing this node.
if (TLO.Old.Val->use_empty()) {
removeFromWorkList(TLO.Old.Val);
// If the operands of this node are only used by the node, they will now
// be dead. Make sure to visit them first to delete dead nodes early.
for (unsigned i = 0, e = TLO.Old.Val->getNumOperands(); i != e; ++i)
if (TLO.Old.Val->getOperand(i).Val->hasOneUse())
AddToWorkList(TLO.Old.Val->getOperand(i).Val);
DAG.DeleteNode(TLO.Old.Val);
}
return true;
}
//===----------------------------------------------------------------------===//
// Main DAG Combiner implementation
//===----------------------------------------------------------------------===//
void DAGCombiner::Run(bool RunningAfterLegalize) {
// set the instance variable, so that the various visit routines may use it.
AfterLegalize = RunningAfterLegalize;
// Add all the dag nodes to the worklist.
for (SelectionDAG::allnodes_iterator I = DAG.allnodes_begin(),
E = DAG.allnodes_end(); I != E; ++I)
WorkList.push_back(I);
// Create a dummy node (which is not added to allnodes), that adds a reference
// to the root node, preventing it from being deleted, and tracking any
// changes of the root.
HandleSDNode Dummy(DAG.getRoot());
// The root of the dag may dangle to deleted nodes until the dag combiner is
// done. Set it to null to avoid confusion.
DAG.setRoot(SDOperand());
// while the worklist isn't empty, inspect the node on the end of it and
// try and combine it.
while (!WorkList.empty()) {
SDNode *N = WorkList.back();
WorkList.pop_back();
// If N has no uses, it is dead. Make sure to revisit all N's operands once
// N is deleted from the DAG, since they too may now be dead or may have a
// reduced number of uses, allowing other xforms.
if (N->use_empty() && N != &Dummy) {
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
AddToWorkList(N->getOperand(i).Val);
DAG.DeleteNode(N);
continue;
}
SDOperand RV = combine(N);
if (RV.Val == 0)
continue;
++NodesCombined;
// If we get back the same node we passed in, rather than a new node or
// zero, we know that the node must have defined multiple values and
// CombineTo was used. Since CombineTo takes care of the worklist
// mechanics for us, we have no work to do in this case.
if (RV.Val == N)
continue;
assert(N->getOpcode() != ISD::DELETED_NODE &&
RV.Val->getOpcode() != ISD::DELETED_NODE &&
"Node was deleted but visit returned new node!");
DOUT << "\nReplacing.3 "; DEBUG(N->dump(&DAG));
DOUT << "\nWith: "; DEBUG(RV.Val->dump(&DAG));
DOUT << '\n';
WorkListRemover DeadNodes(*this);
if (N->getNumValues() == RV.Val->getNumValues())
DAG.ReplaceAllUsesWith(N, RV.Val, &DeadNodes);
else {
assert(N->getValueType(0) == RV.getValueType() &&
N->getNumValues() == 1 && "Type mismatch");
SDOperand OpV = RV;
DAG.ReplaceAllUsesWith(N, &OpV, &DeadNodes);
}
// Push the new node and any users onto the worklist
AddToWorkList(RV.Val);
AddUsersToWorkList(RV.Val);
// Add any uses of the old node to the worklist in case this node is the
// last one that uses them. They may become dead after this node is
// deleted.
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
AddToWorkList(N->getOperand(i).Val);
// Nodes can be reintroduced into the worklist. Make sure we do not
// process a node that has been replaced.
removeFromWorkList(N);
// Finally, since the node is now dead, remove it from the graph.
DAG.DeleteNode(N);
}
// If the root changed (e.g. it was a dead load, update the root).
DAG.setRoot(Dummy.getValue());
}
SDOperand DAGCombiner::visit(SDNode *N) {
switch(N->getOpcode()) {
default: break;
case ISD::TokenFactor: return visitTokenFactor(N);
case ISD::MERGE_VALUES: return visitMERGE_VALUES(N);
case ISD::ADD: return visitADD(N);
case ISD::SUB: return visitSUB(N);
case ISD::ADDC: return visitADDC(N);
case ISD::ADDE: return visitADDE(N);
case ISD::MUL: return visitMUL(N);
case ISD::SDIV: return visitSDIV(N);
case ISD::UDIV: return visitUDIV(N);
case ISD::SREM: return visitSREM(N);
case ISD::UREM: return visitUREM(N);
case ISD::MULHU: return visitMULHU(N);
case ISD::MULHS: return visitMULHS(N);
case ISD::SMUL_LOHI: return visitSMUL_LOHI(N);
case ISD::UMUL_LOHI: return visitUMUL_LOHI(N);
case ISD::SDIVREM: return visitSDIVREM(N);
case ISD::UDIVREM: return visitUDIVREM(N);
case ISD::AND: return visitAND(N);
case ISD::OR: return visitOR(N);
case ISD::XOR: return visitXOR(N);
case ISD::SHL: return visitSHL(N);
case ISD::SRA: return visitSRA(N);
case ISD::SRL: return visitSRL(N);
case ISD::CTLZ: return visitCTLZ(N);
case ISD::CTTZ: return visitCTTZ(N);
case ISD::CTPOP: return visitCTPOP(N);
case ISD::SELECT: return visitSELECT(N);
case ISD::SELECT_CC: return visitSELECT_CC(N);
case ISD::SETCC: return visitSETCC(N);
case ISD::SIGN_EXTEND: return visitSIGN_EXTEND(N);
case ISD::ZERO_EXTEND: return visitZERO_EXTEND(N);
case ISD::ANY_EXTEND: return visitANY_EXTEND(N);
case ISD::SIGN_EXTEND_INREG: return visitSIGN_EXTEND_INREG(N);
case ISD::TRUNCATE: return visitTRUNCATE(N);
case ISD::BIT_CONVERT: return visitBIT_CONVERT(N);
case ISD::BUILD_PAIR: return visitBUILD_PAIR(N);
case ISD::FADD: return visitFADD(N);
case ISD::FSUB: return visitFSUB(N);
case ISD::FMUL: return visitFMUL(N);
case ISD::FDIV: return visitFDIV(N);
case ISD::FREM: return visitFREM(N);
case ISD::FCOPYSIGN: return visitFCOPYSIGN(N);
case ISD::SINT_TO_FP: return visitSINT_TO_FP(N);
case ISD::UINT_TO_FP: return visitUINT_TO_FP(N);
case ISD::FP_TO_SINT: return visitFP_TO_SINT(N);
case ISD::FP_TO_UINT: return visitFP_TO_UINT(N);
case ISD::FP_ROUND: return visitFP_ROUND(N);
case ISD::FP_ROUND_INREG: return visitFP_ROUND_INREG(N);
case ISD::FP_EXTEND: return visitFP_EXTEND(N);
case ISD::FNEG: return visitFNEG(N);
case ISD::FABS: return visitFABS(N);
case ISD::BRCOND: return visitBRCOND(N);
case ISD::BR_CC: return visitBR_CC(N);
case ISD::LOAD: return visitLOAD(N);
case ISD::STORE: return visitSTORE(N);
case ISD::INSERT_VECTOR_ELT: return visitINSERT_VECTOR_ELT(N);
case ISD::EXTRACT_VECTOR_ELT: return visitEXTRACT_VECTOR_ELT(N);
case ISD::BUILD_VECTOR: return visitBUILD_VECTOR(N);
case ISD::CONCAT_VECTORS: return visitCONCAT_VECTORS(N);
case ISD::VECTOR_SHUFFLE: return visitVECTOR_SHUFFLE(N);
}
return SDOperand();
}
SDOperand DAGCombiner::combine(SDNode *N) {
SDOperand RV = visit(N);
// If nothing happened, try a target-specific DAG combine.
if (RV.Val == 0) {
assert(N->getOpcode() != ISD::DELETED_NODE &&
"Node was deleted but visit returned NULL!");
if (N->getOpcode() >= ISD::BUILTIN_OP_END ||
TLI.hasTargetDAGCombine((ISD::NodeType)N->getOpcode())) {
// Expose the DAG combiner to the target combiner impls.
TargetLowering::DAGCombinerInfo
DagCombineInfo(DAG, !AfterLegalize, false, this);
RV = TLI.PerformDAGCombine(N, DagCombineInfo);
}
}
// If N is a commutative binary node, try commuting it to enable more
// sdisel CSE.
if (RV.Val == 0 &&
SelectionDAG::isCommutativeBinOp(N->getOpcode()) &&
N->getNumValues() == 1) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
// Constant operands are canonicalized to RHS.
if (isa<ConstantSDNode>(N0) || !isa<ConstantSDNode>(N1)) {
SDOperand Ops[] = { N1, N0 };
SDNode *CSENode = DAG.getNodeIfExists(N->getOpcode(), N->getVTList(),
Ops, 2);
if (CSENode)
return SDOperand(CSENode, 0);
}
}
return RV;
}
/// getInputChainForNode - Given a node, return its input chain if it has one,
/// otherwise return a null sd operand.
static SDOperand getInputChainForNode(SDNode *N) {
if (unsigned NumOps = N->getNumOperands()) {
if (N->getOperand(0).getValueType() == MVT::Other)
return N->getOperand(0);
else if (N->getOperand(NumOps-1).getValueType() == MVT::Other)
return N->getOperand(NumOps-1);
for (unsigned i = 1; i < NumOps-1; ++i)
if (N->getOperand(i).getValueType() == MVT::Other)
return N->getOperand(i);
}
return SDOperand(0, 0);
}
SDOperand DAGCombiner::visitTokenFactor(SDNode *N) {
// If N has two operands, where one has an input chain equal to the other,
// the 'other' chain is redundant.
if (N->getNumOperands() == 2) {
if (getInputChainForNode(N->getOperand(0).Val) == N->getOperand(1))
return N->getOperand(0);
if (getInputChainForNode(N->getOperand(1).Val) == N->getOperand(0))
return N->getOperand(1);
}
SmallVector<SDNode *, 8> TFs; // List of token factors to visit.
SmallVector<SDOperand, 8> Ops; // Ops for replacing token factor.
SmallPtrSet<SDNode*, 16> SeenOps;
bool Changed = false; // If we should replace this token factor.
// Start out with this token factor.
TFs.push_back(N);
// Iterate through token factors. The TFs grows when new token factors are
// encountered.
for (unsigned i = 0; i < TFs.size(); ++i) {
SDNode *TF = TFs[i];
// Check each of the operands.
for (unsigned i = 0, ie = TF->getNumOperands(); i != ie; ++i) {
SDOperand Op = TF->getOperand(i);
switch (Op.getOpcode()) {
case ISD::EntryToken:
// Entry tokens don't need to be added to the list. They are
// rededundant.
Changed = true;
break;
case ISD::TokenFactor:
if ((CombinerAA || Op.hasOneUse()) &&
std::find(TFs.begin(), TFs.end(), Op.Val) == TFs.end()) {
// Queue up for processing.
TFs.push_back(Op.Val);
// Clean up in case the token factor is removed.
AddToWorkList(Op.Val);
Changed = true;
break;
}
// Fall thru
default:
// Only add if it isn't already in the list.
if (SeenOps.insert(Op.Val))
Ops.push_back(Op);
else
Changed = true;
break;
}
}
}
SDOperand Result;
// If we've change things around then replace token factor.
if (Changed) {
if (Ops.empty()) {
// The entry token is the only possible outcome.
Result = DAG.getEntryNode();
} else {
// New and improved token factor.
Result = DAG.getNode(ISD::TokenFactor, MVT::Other, &Ops[0], Ops.size());
}
// Don't add users to work list.
return CombineTo(N, Result, false);
}
return Result;
}
/// MERGE_VALUES can always be eliminated.
SDOperand DAGCombiner::visitMERGE_VALUES(SDNode *N) {
WorkListRemover DeadNodes(*this);
for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i)
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, i), N->getOperand(i),
&DeadNodes);
removeFromWorkList(N);
DAG.DeleteNode(N);
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
static
SDOperand combineShlAddConstant(SDOperand N0, SDOperand N1, SelectionDAG &DAG) {
MVT VT = N0.getValueType();
SDOperand N00 = N0.getOperand(0);
SDOperand N01 = N0.getOperand(1);
ConstantSDNode *N01C = dyn_cast<ConstantSDNode>(N01);
if (N01C && N00.getOpcode() == ISD::ADD && N00.Val->hasOneUse() &&
isa<ConstantSDNode>(N00.getOperand(1))) {
N0 = DAG.getNode(ISD::ADD, VT,
DAG.getNode(ISD::SHL, VT, N00.getOperand(0), N01),
DAG.getNode(ISD::SHL, VT, N00.getOperand(1), N01));
return DAG.getNode(ISD::ADD, VT, N0, N1);
}
return SDOperand();
}
static
SDOperand combineSelectAndUse(SDNode *N, SDOperand Slct, SDOperand OtherOp,
SelectionDAG &DAG) {
MVT VT = N->getValueType(0);
unsigned Opc = N->getOpcode();
bool isSlctCC = Slct.getOpcode() == ISD::SELECT_CC;
SDOperand LHS = isSlctCC ? Slct.getOperand(2) : Slct.getOperand(1);
SDOperand RHS = isSlctCC ? Slct.getOperand(3) : Slct.getOperand(2);
ISD::CondCode CC = ISD::SETCC_INVALID;
if (isSlctCC)
CC = cast<CondCodeSDNode>(Slct.getOperand(4))->get();
else {
SDOperand CCOp = Slct.getOperand(0);
if (CCOp.getOpcode() == ISD::SETCC)
CC = cast<CondCodeSDNode>(CCOp.getOperand(2))->get();
}
bool DoXform = false;
bool InvCC = false;
assert ((Opc == ISD::ADD || (Opc == ISD::SUB && Slct == N->getOperand(1))) &&
"Bad input!");
if (LHS.getOpcode() == ISD::Constant &&
cast<ConstantSDNode>(LHS)->isNullValue())
DoXform = true;
else if (CC != ISD::SETCC_INVALID &&
RHS.getOpcode() == ISD::Constant &&
cast<ConstantSDNode>(RHS)->isNullValue()) {
std::swap(LHS, RHS);
SDOperand Op0 = Slct.getOperand(0);
bool isInt = (isSlctCC ? Op0.getValueType() :
Op0.getOperand(0).getValueType()).isInteger();
CC = ISD::getSetCCInverse(CC, isInt);
DoXform = true;
InvCC = true;
}
if (DoXform) {
SDOperand Result = DAG.getNode(Opc, VT, OtherOp, RHS);
if (isSlctCC)
return DAG.getSelectCC(OtherOp, Result,
Slct.getOperand(0), Slct.getOperand(1), CC);
SDOperand CCOp = Slct.getOperand(0);
if (InvCC)
CCOp = DAG.getSetCC(CCOp.getValueType(), CCOp.getOperand(0),
CCOp.getOperand(1), CC);
return DAG.getNode(ISD::SELECT, VT, CCOp, OtherOp, Result);
}
return SDOperand();
}
SDOperand DAGCombiner::visitADD(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
MVT VT = N0.getValueType();
// fold vector ops
if (VT.isVector()) {
SDOperand FoldedVOp = SimplifyVBinOp(N);
if (FoldedVOp.Val) return FoldedVOp;
}
// fold (add x, undef) -> undef
if (N0.getOpcode() == ISD::UNDEF)
return N0;
if (N1.getOpcode() == ISD::UNDEF)
return N1;
// fold (add c1, c2) -> c1+c2
if (N0C && N1C)
return DAG.getConstant(N0C->getAPIntValue() + N1C->getAPIntValue(), VT);
// canonicalize constant to RHS
if (N0C && !N1C)
return DAG.getNode(ISD::ADD, VT, N1, N0);
// fold (add x, 0) -> x
if (N1C && N1C->isNullValue())
return N0;
// fold ((c1-A)+c2) -> (c1+c2)-A
if (N1C && N0.getOpcode() == ISD::SUB)
if (ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.getOperand(0)))
return DAG.getNode(ISD::SUB, VT,
DAG.getConstant(N1C->getAPIntValue()+
N0C->getAPIntValue(), VT),
N0.getOperand(1));
// reassociate add
SDOperand RADD = ReassociateOps(ISD::ADD, N0, N1);
if (RADD.Val != 0)
return RADD;
// fold ((0-A) + B) -> B-A
if (N0.getOpcode() == ISD::SUB && isa<ConstantSDNode>(N0.getOperand(0)) &&
cast<ConstantSDNode>(N0.getOperand(0))->isNullValue())
return DAG.getNode(ISD::SUB, VT, N1, N0.getOperand(1));
// fold (A + (0-B)) -> A-B
if (N1.getOpcode() == ISD::SUB && isa<ConstantSDNode>(N1.getOperand(0)) &&
cast<ConstantSDNode>(N1.getOperand(0))->isNullValue())
return DAG.getNode(ISD::SUB, VT, N0, N1.getOperand(1));
// fold (A+(B-A)) -> B
if (N1.getOpcode() == ISD::SUB && N0 == N1.getOperand(1))
return N1.getOperand(0);
if (!VT.isVector() && SimplifyDemandedBits(SDOperand(N, 0)))
return SDOperand(N, 0);
// fold (a+b) -> (a|b) iff a and b share no bits.
if (VT.isInteger() && !VT.isVector()) {
APInt LHSZero, LHSOne;
APInt RHSZero, RHSOne;
APInt Mask = APInt::getAllOnesValue(VT.getSizeInBits());
DAG.ComputeMaskedBits(N0, Mask, LHSZero, LHSOne);
if (LHSZero.getBoolValue()) {
DAG.ComputeMaskedBits(N1, Mask, RHSZero, RHSOne);
// If all possibly-set bits on the LHS are clear on the RHS, return an OR.
// If all possibly-set bits on the RHS are clear on the LHS, return an OR.
if ((RHSZero & (~LHSZero & Mask)) == (~LHSZero & Mask) ||
(LHSZero & (~RHSZero & Mask)) == (~RHSZero & Mask))
return DAG.getNode(ISD::OR, VT, N0, N1);
}
}
// fold (add (shl (add x, c1), c2), ) -> (add (add (shl x, c2), c1<<c2), )
if (N0.getOpcode() == ISD::SHL && N0.Val->hasOneUse()) {
SDOperand Result = combineShlAddConstant(N0, N1, DAG);
if (Result.Val) return Result;
}
if (N1.getOpcode() == ISD::SHL && N1.Val->hasOneUse()) {
SDOperand Result = combineShlAddConstant(N1, N0, DAG);
if (Result.Val) return Result;
}
// fold (add (select cc, 0, c), x) -> (select cc, x, (add, x, c))
if (N0.getOpcode() == ISD::SELECT && N0.Val->hasOneUse()) {
SDOperand Result = combineSelectAndUse(N, N0, N1, DAG);
if (Result.Val) return Result;
}
if (N1.getOpcode() == ISD::SELECT && N1.Val->hasOneUse()) {
SDOperand Result = combineSelectAndUse(N, N1, N0, DAG);
if (Result.Val) return Result;
}
return SDOperand();
}
SDOperand DAGCombiner::visitADDC(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
MVT VT = N0.getValueType();
// If the flag result is dead, turn this into an ADD.
if (N->hasNUsesOfValue(0, 1))
return CombineTo(N, DAG.getNode(ISD::ADD, VT, N1, N0),
DAG.getNode(ISD::CARRY_FALSE, MVT::Flag));
// canonicalize constant to RHS.
if (N0C && !N1C) {
return DAG.getNode(ISD::ADDC, N->getVTList(), N1, N0);
}
// fold (addc x, 0) -> x + no carry out
if (N1C && N1C->isNullValue())
return CombineTo(N, N0, DAG.getNode(ISD::CARRY_FALSE, MVT::Flag));
// fold (addc a, b) -> (or a, b), CARRY_FALSE iff a and b share no bits.
APInt LHSZero, LHSOne;
APInt RHSZero, RHSOne;
APInt Mask = APInt::getAllOnesValue(VT.getSizeInBits());
DAG.ComputeMaskedBits(N0, Mask, LHSZero, LHSOne);
if (LHSZero.getBoolValue()) {
DAG.ComputeMaskedBits(N1, Mask, RHSZero, RHSOne);
// If all possibly-set bits on the LHS are clear on the RHS, return an OR.
// If all possibly-set bits on the RHS are clear on the LHS, return an OR.
if ((RHSZero & (~LHSZero & Mask)) == (~LHSZero & Mask) ||
(LHSZero & (~RHSZero & Mask)) == (~RHSZero & Mask))
return CombineTo(N, DAG.getNode(ISD::OR, VT, N0, N1),
DAG.getNode(ISD::CARRY_FALSE, MVT::Flag));
}
return SDOperand();
}
SDOperand DAGCombiner::visitADDE(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
SDOperand CarryIn = N->getOperand(2);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
//MVT VT = N0.getValueType();
// canonicalize constant to RHS
if (N0C && !N1C) {
return DAG.getNode(ISD::ADDE, N->getVTList(), N1, N0, CarryIn);
}
// fold (adde x, y, false) -> (addc x, y)
if (CarryIn.getOpcode() == ISD::CARRY_FALSE) {
return DAG.getNode(ISD::ADDC, N->getVTList(), N1, N0);
}
return SDOperand();
}
SDOperand DAGCombiner::visitSUB(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.Val);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val);
MVT VT = N0.getValueType();
// fold vector ops
if (VT.isVector()) {
SDOperand FoldedVOp = SimplifyVBinOp(N);
if (FoldedVOp.Val) return FoldedVOp;
}
// fold (sub x, x) -> 0
if (N0 == N1)
return DAG.getConstant(0, N->getValueType(0));
// fold (sub c1, c2) -> c1-c2
if (N0C && N1C)
return DAG.getNode(ISD::SUB, VT, N0, N1);
// fold (sub x, c) -> (add x, -c)
if (N1C)
return DAG.getNode(ISD::ADD, VT, N0,
DAG.getConstant(-N1C->getAPIntValue(), VT));
// fold (A+B)-A -> B
if (N0.getOpcode() == ISD::ADD && N0.getOperand(0) == N1)
return N0.getOperand(1);
// fold (A+B)-B -> A
if (N0.getOpcode() == ISD::ADD && N0.getOperand(1) == N1)
return N0.getOperand(0);
// fold (sub x, (select cc, 0, c)) -> (select cc, x, (sub, x, c))
if (N1.getOpcode() == ISD::SELECT && N1.Val->hasOneUse()) {
SDOperand Result = combineSelectAndUse(N, N1, N0, DAG);
if (Result.Val) return Result;
}
// If either operand of a sub is undef, the result is undef
if (N0.getOpcode() == ISD::UNDEF)
return N0;
if (N1.getOpcode() == ISD::UNDEF)
return N1;
return SDOperand();
}
SDOperand DAGCombiner::visitMUL(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
MVT VT = N0.getValueType();
// fold vector ops
if (VT.isVector()) {
SDOperand FoldedVOp = SimplifyVBinOp(N);
if (FoldedVOp.Val) return FoldedVOp;
}
// fold (mul x, undef) -> 0
if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF)
return DAG.getConstant(0, VT);
// fold (mul c1, c2) -> c1*c2
if (N0C && N1C)
return DAG.getNode(ISD::MUL, VT, N0, N1);
// canonicalize constant to RHS
if (N0C && !N1C)
return DAG.getNode(ISD::MUL, VT, N1, N0);
// fold (mul x, 0) -> 0
if (N1C && N1C->isNullValue())
return N1;
// fold (mul x, -1) -> 0-x
if (N1C && N1C->isAllOnesValue())
return DAG.getNode(ISD::SUB, VT, DAG.getConstant(0, VT), N0);
// fold (mul x, (1 << c)) -> x << c
if (N1C && N1C->getAPIntValue().isPowerOf2())
return DAG.getNode(ISD::SHL, VT, N0,
DAG.getConstant(N1C->getAPIntValue().logBase2(),
TLI.getShiftAmountTy()));
// fold (mul x, -(1 << c)) -> -(x << c) or (-x) << c
if (N1C && isPowerOf2_64(-N1C->getSignExtended())) {
// FIXME: If the input is something that is easily negated (e.g. a
// single-use add), we should put the negate there.
return DAG.getNode(ISD::SUB, VT, DAG.getConstant(0, VT),
DAG.getNode(ISD::SHL, VT, N0,
DAG.getConstant(Log2_64(-N1C->getSignExtended()),
TLI.getShiftAmountTy())));
}
// (mul (shl X, c1), c2) -> (mul X, c2 << c1)
if (N1C && N0.getOpcode() == ISD::SHL &&
isa<ConstantSDNode>(N0.getOperand(1))) {
SDOperand C3 = DAG.getNode(ISD::SHL, VT, N1, N0.getOperand(1));
AddToWorkList(C3.Val);
return DAG.getNode(ISD::MUL, VT, N0.getOperand(0), C3);
}
// Change (mul (shl X, C), Y) -> (shl (mul X, Y), C) when the shift has one
// use.
{
SDOperand Sh(0,0), Y(0,0);
// Check for both (mul (shl X, C), Y) and (mul Y, (shl X, C)).
if (N0.getOpcode() == ISD::SHL && isa<ConstantSDNode>(N0.getOperand(1)) &&
N0.Val->hasOneUse()) {
Sh = N0; Y = N1;
} else if (N1.getOpcode() == ISD::SHL &&
isa<ConstantSDNode>(N1.getOperand(1)) && N1.Val->hasOneUse()) {
Sh = N1; Y = N0;
}
if (Sh.Val) {
SDOperand Mul = DAG.getNode(ISD::MUL, VT, Sh.getOperand(0), Y);
return DAG.getNode(ISD::SHL, VT, Mul, Sh.getOperand(1));
}
}
// fold (mul (add x, c1), c2) -> (add (mul x, c2), c1*c2)
if (N1C && N0.getOpcode() == ISD::ADD && N0.Val->hasOneUse() &&
isa<ConstantSDNode>(N0.getOperand(1))) {
return DAG.getNode(ISD::ADD, VT,
DAG.getNode(ISD::MUL, VT, N0.getOperand(0), N1),
DAG.getNode(ISD::MUL, VT, N0.getOperand(1), N1));
}
// reassociate mul
SDOperand RMUL = ReassociateOps(ISD::MUL, N0, N1);
if (RMUL.Val != 0)
return RMUL;
return SDOperand();
}
SDOperand DAGCombiner::visitSDIV(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.Val);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val);
MVT VT = N->getValueType(0);
// fold vector ops
if (VT.isVector()) {
SDOperand FoldedVOp = SimplifyVBinOp(N);
if (FoldedVOp.Val) return FoldedVOp;
}
// fold (sdiv c1, c2) -> c1/c2
if (N0C && N1C && !N1C->isNullValue())
return DAG.getNode(ISD::SDIV, VT, N0, N1);
// fold (sdiv X, 1) -> X
if (N1C && N1C->getSignExtended() == 1LL)
return N0;
// fold (sdiv X, -1) -> 0-X
if (N1C && N1C->isAllOnesValue())
return DAG.getNode(ISD::SUB, VT, DAG.getConstant(0, VT), N0);
// If we know the sign bits of both operands are zero, strength reduce to a
// udiv instead. Handles (X&15) /s 4 -> X&15 >> 2
if (!VT.isVector()) {
if (DAG.SignBitIsZero(N1) && DAG.SignBitIsZero(N0))
return DAG.getNode(ISD::UDIV, N1.getValueType(), N0, N1);
}
// fold (sdiv X, pow2) -> simple ops after legalize
if (N1C && !N1C->isNullValue() && !TLI.isIntDivCheap() &&
(isPowerOf2_64(N1C->getSignExtended()) ||
isPowerOf2_64(-N1C->getSignExtended()))) {
// If dividing by powers of two is cheap, then don't perform the following
// fold.
if (TLI.isPow2DivCheap())
return SDOperand();
int64_t pow2 = N1C->getSignExtended();
int64_t abs2 = pow2 > 0 ? pow2 : -pow2;
unsigned lg2 = Log2_64(abs2);
// Splat the sign bit into the register
SDOperand SGN = DAG.getNode(ISD::SRA, VT, N0,
DAG.getConstant(VT.getSizeInBits()-1,
TLI.getShiftAmountTy()));
AddToWorkList(SGN.Val);
// Add (N0 < 0) ? abs2 - 1 : 0;
SDOperand SRL = DAG.getNode(ISD::SRL, VT, SGN,
DAG.getConstant(VT.getSizeInBits()-lg2,
TLI.getShiftAmountTy()));
SDOperand ADD = DAG.getNode(ISD::ADD, VT, N0, SRL);
AddToWorkList(SRL.Val);
AddToWorkList(ADD.Val); // Divide by pow2
SDOperand SRA = DAG.getNode(ISD::SRA, VT, ADD,
DAG.getConstant(lg2, TLI.getShiftAmountTy()));
// If we're dividing by a positive value, we're done. Otherwise, we must
// negate the result.
if (pow2 > 0)
return SRA;
AddToWorkList(SRA.Val);
return DAG.getNode(ISD::SUB, VT, DAG.getConstant(0, VT), SRA);
}
// if integer divide is expensive and we satisfy the requirements, emit an
// alternate sequence.
if (N1C && (N1C->getSignExtended() < -1 || N1C->getSignExtended() > 1) &&
!TLI.isIntDivCheap()) {
SDOperand Op = BuildSDIV(N);
if (Op.Val) return Op;
}
// undef / X -> 0
if (N0.getOpcode() == ISD::UNDEF)
return DAG.getConstant(0, VT);
// X / undef -> undef
if (N1.getOpcode() == ISD::UNDEF)
return N1;
return SDOperand();
}
SDOperand DAGCombiner::visitUDIV(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.Val);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val);
MVT VT = N->getValueType(0);
// fold vector ops
if (VT.isVector()) {
SDOperand FoldedVOp = SimplifyVBinOp(N);
if (FoldedVOp.Val) return FoldedVOp;
}
// fold (udiv c1, c2) -> c1/c2
if (N0C && N1C && !N1C->isNullValue())
return DAG.getNode(ISD::UDIV, VT, N0, N1);
// fold (udiv x, (1 << c)) -> x >>u c
if (N1C && N1C->getAPIntValue().isPowerOf2())
return DAG.getNode(ISD::SRL, VT, N0,
DAG.getConstant(N1C->getAPIntValue().logBase2(),
TLI.getShiftAmountTy()));
// fold (udiv x, (shl c, y)) -> x >>u (log2(c)+y) iff c is power of 2
if (N1.getOpcode() == ISD::SHL) {
if (ConstantSDNode *SHC = dyn_cast<ConstantSDNode>(N1.getOperand(0))) {
if (SHC->getAPIntValue().isPowerOf2()) {
MVT ADDVT = N1.getOperand(1).getValueType();
SDOperand Add = DAG.getNode(ISD::ADD, ADDVT, N1.getOperand(1),
DAG.getConstant(SHC->getAPIntValue()
.logBase2(),
ADDVT));
AddToWorkList(Add.Val);
return DAG.getNode(ISD::SRL, VT, N0, Add);
}
}
}
// fold (udiv x, c) -> alternate
if (N1C && !N1C->isNullValue() && !TLI.isIntDivCheap()) {
SDOperand Op = BuildUDIV(N);
if (Op.Val) return Op;
}
// undef / X -> 0
if (N0.getOpcode() == ISD::UNDEF)
return DAG.getConstant(0, VT);
// X / undef -> undef
if (N1.getOpcode() == ISD::UNDEF)
return N1;
return SDOperand();
}
SDOperand DAGCombiner::visitSREM(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
MVT VT = N->getValueType(0);
// fold (srem c1, c2) -> c1%c2
if (N0C && N1C && !N1C->isNullValue())
return DAG.getNode(ISD::SREM, VT, N0, N1);
// If we know the sign bits of both operands are zero, strength reduce to a
// urem instead. Handles (X & 0x0FFFFFFF) %s 16 -> X&15
if (!VT.isVector()) {
if (DAG.SignBitIsZero(N1) && DAG.SignBitIsZero(N0))
return DAG.getNode(ISD::UREM, VT, N0, N1);
}
// If X/C can be simplified by the division-by-constant logic, lower
// X%C to the equivalent of X-X/C*C.
if (N1C && !N1C->isNullValue()) {
SDOperand Div = DAG.getNode(ISD::SDIV, VT, N0, N1);
AddToWorkList(Div.Val);
SDOperand OptimizedDiv = combine(Div.Val);
if (OptimizedDiv.Val && OptimizedDiv.Val != Div.Val) {
SDOperand Mul = DAG.getNode(ISD::MUL, VT, OptimizedDiv, N1);
SDOperand Sub = DAG.getNode(ISD::SUB, VT, N0, Mul);
AddToWorkList(Mul.Val);
return Sub;
}
}
// undef % X -> 0
if (N0.getOpcode() == ISD::UNDEF)
return DAG.getConstant(0, VT);
// X % undef -> undef
if (N1.getOpcode() == ISD::UNDEF)
return N1;
return SDOperand();
}
SDOperand DAGCombiner::visitUREM(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
MVT VT = N->getValueType(0);
// fold (urem c1, c2) -> c1%c2
if (N0C && N1C && !N1C->isNullValue())
return DAG.getNode(ISD::UREM, VT, N0, N1);
// fold (urem x, pow2) -> (and x, pow2-1)
if (N1C && !N1C->isNullValue() && N1C->getAPIntValue().isPowerOf2())
return DAG.getNode(ISD::AND, VT, N0,
DAG.getConstant(N1C->getAPIntValue()-1,VT));
// fold (urem x, (shl pow2, y)) -> (and x, (add (shl pow2, y), -1))
if (N1.getOpcode() == ISD::SHL) {
if (ConstantSDNode *SHC = dyn_cast<ConstantSDNode>(N1.getOperand(0))) {
if (SHC->getAPIntValue().isPowerOf2()) {
SDOperand Add =
DAG.getNode(ISD::ADD, VT, N1,
DAG.getConstant(APInt::getAllOnesValue(VT.getSizeInBits()),
VT));
AddToWorkList(Add.Val);
return DAG.getNode(ISD::AND, VT, N0, Add);
}
}
}
// If X/C can be simplified by the division-by-constant logic, lower
// X%C to the equivalent of X-X/C*C.
if (N1C && !N1C->isNullValue()) {
SDOperand Div = DAG.getNode(ISD::UDIV, VT, N0, N1);
SDOperand OptimizedDiv = combine(Div.Val);
if (OptimizedDiv.Val && OptimizedDiv.Val != Div.Val) {
SDOperand Mul = DAG.getNode(ISD::MUL, VT, OptimizedDiv, N1);
SDOperand Sub = DAG.getNode(ISD::SUB, VT, N0, Mul);
AddToWorkList(Mul.Val);
return Sub;
}
}
// undef % X -> 0
if (N0.getOpcode() == ISD::UNDEF)
return DAG.getConstant(0, VT);
// X % undef -> undef
if (N1.getOpcode() == ISD::UNDEF)
return N1;
return SDOperand();
}
SDOperand DAGCombiner::visitMULHS(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
MVT VT = N->getValueType(0);
// fold (mulhs x, 0) -> 0
if (N1C && N1C->isNullValue())
return N1;
// fold (mulhs x, 1) -> (sra x, size(x)-1)
if (N1C && N1C->getAPIntValue() == 1)
return DAG.getNode(ISD::SRA, N0.getValueType(), N0,
DAG.getConstant(N0.getValueType().getSizeInBits()-1,
TLI.getShiftAmountTy()));
// fold (mulhs x, undef) -> 0
if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF)
return DAG.getConstant(0, VT);
return SDOperand();
}
SDOperand DAGCombiner::visitMULHU(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
MVT VT = N->getValueType(0);
// fold (mulhu x, 0) -> 0
if (N1C && N1C->isNullValue())
return N1;
// fold (mulhu x, 1) -> 0
if (N1C && N1C->getAPIntValue() == 1)
return DAG.getConstant(0, N0.getValueType());
// fold (mulhu x, undef) -> 0
if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF)
return DAG.getConstant(0, VT);
return SDOperand();
}
/// SimplifyNodeWithTwoResults - Perform optimizations common to nodes that
/// compute two values. LoOp and HiOp give the opcodes for the two computations
/// that are being performed. Return true if a simplification was made.
///
SDOperand DAGCombiner::SimplifyNodeWithTwoResults(SDNode *N, unsigned LoOp,
unsigned HiOp) {
// If the high half is not needed, just compute the low half.
bool HiExists = N->hasAnyUseOfValue(1);
if (!HiExists &&
(!AfterLegalize ||
TLI.isOperationLegal(LoOp, N->getValueType(0)))) {
SDOperand Res = DAG.getNode(LoOp, N->getValueType(0), N->op_begin(),
N->getNumOperands());
return CombineTo(N, Res, Res);
}
// If the low half is not needed, just compute the high half.
bool LoExists = N->hasAnyUseOfValue(0);
if (!LoExists &&
(!AfterLegalize ||
TLI.isOperationLegal(HiOp, N->getValueType(1)))) {
SDOperand Res = DAG.getNode(HiOp, N->getValueType(1), N->op_begin(),
N->getNumOperands());
return CombineTo(N, Res, Res);
}
// If both halves are used, return as it is.
if (LoExists && HiExists)
return SDOperand();
// If the two computed results can be simplified separately, separate them.
if (LoExists) {
SDOperand Lo = DAG.getNode(LoOp, N->getValueType(0),
N->op_begin(), N->getNumOperands());
AddToWorkList(Lo.Val);
SDOperand LoOpt = combine(Lo.Val);
if (LoOpt.Val && LoOpt.Val != Lo.Val &&
(!AfterLegalize ||
TLI.isOperationLegal(LoOpt.getOpcode(), LoOpt.getValueType())))
return CombineTo(N, LoOpt, LoOpt);
}
if (HiExists) {
SDOperand Hi = DAG.getNode(HiOp, N->getValueType(1),
N->op_begin(), N->getNumOperands());
AddToWorkList(Hi.Val);
SDOperand HiOpt = combine(Hi.Val);
if (HiOpt.Val && HiOpt != Hi &&
(!AfterLegalize ||
TLI.isOperationLegal(HiOpt.getOpcode(), HiOpt.getValueType())))
return CombineTo(N, HiOpt, HiOpt);
}
return SDOperand();
}
SDOperand DAGCombiner::visitSMUL_LOHI(SDNode *N) {
SDOperand Res = SimplifyNodeWithTwoResults(N, ISD::MUL, ISD::MULHS);
if (Res.Val) return Res;
return SDOperand();
}
SDOperand DAGCombiner::visitUMUL_LOHI(SDNode *N) {
SDOperand Res = SimplifyNodeWithTwoResults(N, ISD::MUL, ISD::MULHU);
if (Res.Val) return Res;
return SDOperand();
}
SDOperand DAGCombiner::visitSDIVREM(SDNode *N) {
SDOperand Res = SimplifyNodeWithTwoResults(N, ISD::SDIV, ISD::SREM);
if (Res.Val) return Res;
return SDOperand();
}
SDOperand DAGCombiner::visitUDIVREM(SDNode *N) {
SDOperand Res = SimplifyNodeWithTwoResults(N, ISD::UDIV, ISD::UREM);
if (Res.Val) return Res;
return SDOperand();
}
/// SimplifyBinOpWithSameOpcodeHands - If this is a binary operator with
/// two operands of the same opcode, try to simplify it.
SDOperand DAGCombiner::SimplifyBinOpWithSameOpcodeHands(SDNode *N) {
SDOperand N0 = N->getOperand(0), N1 = N->getOperand(1);
MVT VT = N0.getValueType();
assert(N0.getOpcode() == N1.getOpcode() && "Bad input!");
// For each of OP in AND/OR/XOR:
// fold (OP (zext x), (zext y)) -> (zext (OP x, y))
// fold (OP (sext x), (sext y)) -> (sext (OP x, y))
// fold (OP (aext x), (aext y)) -> (aext (OP x, y))
// fold (OP (trunc x), (trunc y)) -> (trunc (OP x, y))
if ((N0.getOpcode() == ISD::ZERO_EXTEND || N0.getOpcode() == ISD::ANY_EXTEND||
N0.getOpcode() == ISD::SIGN_EXTEND || N0.getOpcode() == ISD::TRUNCATE) &&
N0.getOperand(0).getValueType() == N1.getOperand(0).getValueType()) {
SDOperand ORNode = DAG.getNode(N->getOpcode(),
N0.getOperand(0).getValueType(),
N0.getOperand(0), N1.getOperand(0));
AddToWorkList(ORNode.Val);
return DAG.getNode(N0.getOpcode(), VT, ORNode);
}
// For each of OP in SHL/SRL/SRA/AND...
// fold (and (OP x, z), (OP y, z)) -> (OP (and x, y), z)
// fold (or (OP x, z), (OP y, z)) -> (OP (or x, y), z)
// fold (xor (OP x, z), (OP y, z)) -> (OP (xor x, y), z)
if ((N0.getOpcode() == ISD::SHL || N0.getOpcode() == ISD::SRL ||
N0.getOpcode() == ISD::SRA || N0.getOpcode() == ISD::AND) &&
N0.getOperand(1) == N1.getOperand(1)) {
SDOperand ORNode = DAG.getNode(N->getOpcode(),
N0.getOperand(0).getValueType(),
N0.getOperand(0), N1.getOperand(0));
AddToWorkList(ORNode.Val);
return DAG.getNode(N0.getOpcode(), VT, ORNode, N0.getOperand(1));
}
return SDOperand();
}
SDOperand DAGCombiner::visitAND(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
SDOperand LL, LR, RL, RR, CC0, CC1;
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
MVT VT = N1.getValueType();
unsigned BitWidth = VT.getSizeInBits();
// fold vector ops
if (VT.isVector()) {
SDOperand FoldedVOp = SimplifyVBinOp(N);
if (FoldedVOp.Val) return FoldedVOp;
}
// fold (and x, undef) -> 0
if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF)
return DAG.getConstant(0, VT);
// fold (and c1, c2) -> c1&c2
if (N0C && N1C)
return DAG.getNode(ISD::AND, VT, N0, N1);
// canonicalize constant to RHS
if (N0C && !N1C)
return DAG.getNode(ISD::AND, VT, N1, N0);
// fold (and x, -1) -> x
if (N1C && N1C->isAllOnesValue())
return N0;
// if (and x, c) is known to be zero, return 0
if (N1C && DAG.MaskedValueIsZero(SDOperand(N, 0),
APInt::getAllOnesValue(BitWidth)))
return DAG.getConstant(0, VT);
// reassociate and
SDOperand RAND = ReassociateOps(ISD::AND, N0, N1);
if (RAND.Val != 0)
return RAND;
// fold (and (or x, 0xFFFF), 0xFF) -> 0xFF
if (N1C && N0.getOpcode() == ISD::OR)
if (ConstantSDNode *ORI = dyn_cast<ConstantSDNode>(N0.getOperand(1)))
if ((ORI->getAPIntValue() & N1C->getAPIntValue()) == N1C->getAPIntValue())
return N1;
// fold (and (any_ext V), c) -> (zero_ext V) if 'and' only clears top bits.
if (N1C && N0.getOpcode() == ISD::ANY_EXTEND) {
SDOperand N0Op0 = N0.getOperand(0);
APInt Mask = ~N1C->getAPIntValue();
Mask.trunc(N0Op0.getValueSizeInBits());
if (DAG.MaskedValueIsZero(N0Op0, Mask)) {
SDOperand Zext = DAG.getNode(ISD::ZERO_EXTEND, N0.getValueType(),
N0Op0);
// Replace uses of the AND with uses of the Zero extend node.
CombineTo(N, Zext);
// We actually want to replace all uses of the any_extend with the
// zero_extend, to avoid duplicating things. This will later cause this
// AND to be folded.
CombineTo(N0.Val, Zext);
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
}
// fold (and (setcc x), (setcc y)) -> (setcc (and x, y))
if (isSetCCEquivalent(N0, LL, LR, CC0) && isSetCCEquivalent(N1, RL, RR, CC1)){
ISD::CondCode Op0 = cast<CondCodeSDNode>(CC0)->get();
ISD::CondCode Op1 = cast<CondCodeSDNode>(CC1)->get();
if (LR == RR && isa<ConstantSDNode>(LR) && Op0 == Op1 &&
LL.getValueType().isInteger()) {
// fold (X == 0) & (Y == 0) -> (X|Y == 0)
if (cast<ConstantSDNode>(LR)->isNullValue() && Op1 == ISD::SETEQ) {
SDOperand ORNode = DAG.getNode(ISD::OR, LR.getValueType(), LL, RL);
AddToWorkList(ORNode.Val);
return DAG.getSetCC(VT, ORNode, LR, Op1);
}
// fold (X == -1) & (Y == -1) -> (X&Y == -1)
if (cast<ConstantSDNode>(LR)->isAllOnesValue() && Op1 == ISD::SETEQ) {
SDOperand ANDNode = DAG.getNode(ISD::AND, LR.getValueType(), LL, RL);
AddToWorkList(ANDNode.Val);
return DAG.getSetCC(VT, ANDNode, LR, Op1);
}
// fold (X > -1) & (Y > -1) -> (X|Y > -1)
if (cast<ConstantSDNode>(LR)->isAllOnesValue() && Op1 == ISD::SETGT) {
SDOperand ORNode = DAG.getNode(ISD::OR, LR.getValueType(), LL, RL);
AddToWorkList(ORNode.Val);
return DAG.getSetCC(VT, ORNode, LR, Op1);
}
}
// canonicalize equivalent to ll == rl
if (LL == RR && LR == RL) {
Op1 = ISD::getSetCCSwappedOperands(Op1);
std::swap(RL, RR);
}
if (LL == RL && LR == RR) {
bool isInteger = LL.getValueType().isInteger();
ISD::CondCode Result = ISD::getSetCCAndOperation(Op0, Op1, isInteger);
if (Result != ISD::SETCC_INVALID)
return DAG.getSetCC(N0.getValueType(), LL, LR, Result);
}
}
// Simplify: and (op x...), (op y...) -> (op (and x, y))
if (N0.getOpcode() == N1.getOpcode()) {
SDOperand Tmp = SimplifyBinOpWithSameOpcodeHands(N);
if (Tmp.Val) return Tmp;
}
// fold (and (sign_extend_inreg x, i16 to i32), 1) -> (and x, 1)
// fold (and (sra)) -> (and (srl)) when possible.
if (!VT.isVector() &&
SimplifyDemandedBits(SDOperand(N, 0)))
return SDOperand(N, 0);
// fold (zext_inreg (extload x)) -> (zextload x)
if (ISD::isEXTLoad(N0.Val) && ISD::isUNINDEXEDLoad(N0.Val)) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
MVT EVT = LN0->getMemoryVT();
// If we zero all the possible extended bits, then we can turn this into
// a zextload if we are running before legalize or the operation is legal.
unsigned BitWidth = N1.getValueSizeInBits();
if (DAG.MaskedValueIsZero(N1, APInt::getHighBitsSet(BitWidth,
BitWidth - EVT.getSizeInBits())) &&
((!AfterLegalize && !LN0->isVolatile()) ||
TLI.isLoadXLegal(ISD::ZEXTLOAD, EVT))) {
SDOperand ExtLoad = DAG.getExtLoad(ISD::ZEXTLOAD, VT, LN0->getChain(),
LN0->getBasePtr(), LN0->getSrcValue(),
LN0->getSrcValueOffset(), EVT,
LN0->isVolatile(),
LN0->getAlignment());
AddToWorkList(N);
CombineTo(N0.Val, ExtLoad, ExtLoad.getValue(1));
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
}
// fold (zext_inreg (sextload x)) -> (zextload x) iff load has one use
if (ISD::isSEXTLoad(N0.Val) && ISD::isUNINDEXEDLoad(N0.Val) &&
N0.hasOneUse()) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
MVT EVT = LN0->getMemoryVT();
// If we zero all the possible extended bits, then we can turn this into
// a zextload if we are running before legalize or the operation is legal.
unsigned BitWidth = N1.getValueSizeInBits();
if (DAG.MaskedValueIsZero(N1, APInt::getHighBitsSet(BitWidth,
BitWidth - EVT.getSizeInBits())) &&
((!AfterLegalize && !LN0->isVolatile()) ||
TLI.isLoadXLegal(ISD::ZEXTLOAD, EVT))) {
SDOperand ExtLoad = DAG.getExtLoad(ISD::ZEXTLOAD, VT, LN0->getChain(),
LN0->getBasePtr(), LN0->getSrcValue(),
LN0->getSrcValueOffset(), EVT,
LN0->isVolatile(),
LN0->getAlignment());
AddToWorkList(N);
CombineTo(N0.Val, ExtLoad, ExtLoad.getValue(1));
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
}
// fold (and (load x), 255) -> (zextload x, i8)
// fold (and (extload x, i16), 255) -> (zextload x, i8)
if (N1C && N0.getOpcode() == ISD::LOAD) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
if (LN0->getExtensionType() != ISD::SEXTLOAD &&
LN0->isUnindexed() && N0.hasOneUse() &&
// Do not change the width of a volatile load.
!LN0->isVolatile()) {
MVT EVT = MVT::Other;
uint32_t ActiveBits = N1C->getAPIntValue().getActiveBits();
if (ActiveBits > 0 && APIntOps::isMask(ActiveBits, N1C->getAPIntValue()))
EVT = MVT::getIntegerVT(ActiveBits);
MVT LoadedVT = LN0->getMemoryVT();
// Do not generate loads of non-round integer types since these can
// be expensive (and would be wrong if the type is not byte sized).
if (EVT != MVT::Other && LoadedVT.bitsGT(EVT) && EVT.isRound() &&
(!AfterLegalize || TLI.isLoadXLegal(ISD::ZEXTLOAD, EVT))) {
MVT PtrType = N0.getOperand(1).getValueType();
// For big endian targets, we need to add an offset to the pointer to
// load the correct bytes. For little endian systems, we merely need to
// read fewer bytes from the same pointer.
unsigned LVTStoreBytes = LoadedVT.getStoreSizeInBits()/8;
unsigned EVTStoreBytes = EVT.getStoreSizeInBits()/8;
unsigned PtrOff = LVTStoreBytes - EVTStoreBytes;
unsigned Alignment = LN0->getAlignment();
SDOperand NewPtr = LN0->getBasePtr();
if (TLI.isBigEndian()) {
NewPtr = DAG.getNode(ISD::ADD, PtrType, NewPtr,
DAG.getConstant(PtrOff, PtrType));
Alignment = MinAlign(Alignment, PtrOff);
}
AddToWorkList(NewPtr.Val);
SDOperand Load =
DAG.getExtLoad(ISD::ZEXTLOAD, VT, LN0->getChain(), NewPtr,
LN0->getSrcValue(), LN0->getSrcValueOffset(), EVT,
LN0->isVolatile(), Alignment);
AddToWorkList(N);
CombineTo(N0.Val, Load, Load.getValue(1));
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
}
}
return SDOperand();
}
SDOperand DAGCombiner::visitOR(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
SDOperand LL, LR, RL, RR, CC0, CC1;
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
MVT VT = N1.getValueType();
// fold vector ops
if (VT.isVector()) {
SDOperand FoldedVOp = SimplifyVBinOp(N);
if (FoldedVOp.Val) return FoldedVOp;
}
// fold (or x, undef) -> -1
if (N0.getOpcode() == ISD::UNDEF || N1.getOpcode() == ISD::UNDEF)
return DAG.getConstant(~0ULL, VT);
// fold (or c1, c2) -> c1|c2
if (N0C && N1C)
return DAG.getNode(ISD::OR, VT, N0, N1);
// canonicalize constant to RHS
if (N0C && !N1C)
return DAG.getNode(ISD::OR, VT, N1, N0);
// fold (or x, 0) -> x
if (N1C && N1C->isNullValue())
return N0;
// fold (or x, -1) -> -1
if (N1C && N1C->isAllOnesValue())
return N1;
// fold (or x, c) -> c iff (x & ~c) == 0
if (N1C && DAG.MaskedValueIsZero(N0, ~N1C->getAPIntValue()))
return N1;
// reassociate or
SDOperand ROR = ReassociateOps(ISD::OR, N0, N1);
if (ROR.Val != 0)
return ROR;
// Canonicalize (or (and X, c1), c2) -> (and (or X, c2), c1|c2)
if (N1C && N0.getOpcode() == ISD::AND && N0.Val->hasOneUse() &&
isa<ConstantSDNode>(N0.getOperand(1))) {
ConstantSDNode *C1 = cast<ConstantSDNode>(N0.getOperand(1));
return DAG.getNode(ISD::AND, VT, DAG.getNode(ISD::OR, VT, N0.getOperand(0),
N1),
DAG.getConstant(N1C->getAPIntValue() |
C1->getAPIntValue(), VT));
}
// fold (or (setcc x), (setcc y)) -> (setcc (or x, y))
if (isSetCCEquivalent(N0, LL, LR, CC0) && isSetCCEquivalent(N1, RL, RR, CC1)){
ISD::CondCode Op0 = cast<CondCodeSDNode>(CC0)->get();
ISD::CondCode Op1 = cast<CondCodeSDNode>(CC1)->get();
if (LR == RR && isa<ConstantSDNode>(LR) && Op0 == Op1 &&
LL.getValueType().isInteger()) {
// fold (X != 0) | (Y != 0) -> (X|Y != 0)
// fold (X < 0) | (Y < 0) -> (X|Y < 0)
if (cast<ConstantSDNode>(LR)->isNullValue() &&
(Op1 == ISD::SETNE || Op1 == ISD::SETLT)) {
SDOperand ORNode = DAG.getNode(ISD::OR, LR.getValueType(), LL, RL);
AddToWorkList(ORNode.Val);
return DAG.getSetCC(VT, ORNode, LR, Op1);
}
// fold (X != -1) | (Y != -1) -> (X&Y != -1)
// fold (X > -1) | (Y > -1) -> (X&Y > -1)
if (cast<ConstantSDNode>(LR)->isAllOnesValue() &&
(Op1 == ISD::SETNE || Op1 == ISD::SETGT)) {
SDOperand ANDNode = DAG.getNode(ISD::AND, LR.getValueType(), LL, RL);
AddToWorkList(ANDNode.Val);
return DAG.getSetCC(VT, ANDNode, LR, Op1);
}
}
// canonicalize equivalent to ll == rl
if (LL == RR && LR == RL) {
Op1 = ISD::getSetCCSwappedOperands(Op1);
std::swap(RL, RR);
}
if (LL == RL && LR == RR) {
bool isInteger = LL.getValueType().isInteger();
ISD::CondCode Result = ISD::getSetCCOrOperation(Op0, Op1, isInteger);
if (Result != ISD::SETCC_INVALID)
return DAG.getSetCC(N0.getValueType(), LL, LR, Result);
}
}
// Simplify: or (op x...), (op y...) -> (op (or x, y))
if (N0.getOpcode() == N1.getOpcode()) {
SDOperand Tmp = SimplifyBinOpWithSameOpcodeHands(N);
if (Tmp.Val) return Tmp;
}
// (X & C1) | (Y & C2) -> (X|Y) & C3 if possible.
if (N0.getOpcode() == ISD::AND &&
N1.getOpcode() == ISD::AND &&
N0.getOperand(1).getOpcode() == ISD::Constant &&
N1.getOperand(1).getOpcode() == ISD::Constant &&
// Don't increase # computations.
(N0.Val->hasOneUse() || N1.Val->hasOneUse())) {
// We can only do this xform if we know that bits from X that are set in C2
// but not in C1 are already zero. Likewise for Y.
const APInt &LHSMask =
cast<ConstantSDNode>(N0.getOperand(1))->getAPIntValue();
const APInt &RHSMask =
cast<ConstantSDNode>(N1.getOperand(1))->getAPIntValue();
if (DAG.MaskedValueIsZero(N0.getOperand(0), RHSMask&~LHSMask) &&
DAG.MaskedValueIsZero(N1.getOperand(0), LHSMask&~RHSMask)) {
SDOperand X =DAG.getNode(ISD::OR, VT, N0.getOperand(0), N1.getOperand(0));
return DAG.getNode(ISD::AND, VT, X, DAG.getConstant(LHSMask|RHSMask, VT));
}
}
// See if this is some rotate idiom.
if (SDNode *Rot = MatchRotate(N0, N1))
return SDOperand(Rot, 0);
return SDOperand();
}
/// MatchRotateHalf - Match "(X shl/srl V1) & V2" where V2 may not be present.
static bool MatchRotateHalf(SDOperand Op, SDOperand &Shift, SDOperand &Mask) {
if (Op.getOpcode() == ISD::AND) {
if (isa<ConstantSDNode>(Op.getOperand(1))) {
Mask = Op.getOperand(1);
Op = Op.getOperand(0);
} else {
return false;
}
}
if (Op.getOpcode() == ISD::SRL || Op.getOpcode() == ISD::SHL) {
Shift = Op;
return true;
}
return false;
}
// MatchRotate - Handle an 'or' of two operands. If this is one of the many
// idioms for rotate, and if the target supports rotation instructions, generate
// a rot[lr].
SDNode *DAGCombiner::MatchRotate(SDOperand LHS, SDOperand RHS) {
// Must be a legal type. Expanded 'n promoted things won't work with rotates.
MVT VT = LHS.getValueType();
if (!TLI.isTypeLegal(VT)) return 0;
// The target must have at least one rotate flavor.
bool HasROTL = TLI.isOperationLegal(ISD::ROTL, VT);
bool HasROTR = TLI.isOperationLegal(ISD::ROTR, VT);
if (!HasROTL && !HasROTR) return 0;
// Match "(X shl/srl V1) & V2" where V2 may not be present.
SDOperand LHSShift; // The shift.
SDOperand LHSMask; // AND value if any.
if (!MatchRotateHalf(LHS, LHSShift, LHSMask))
return 0; // Not part of a rotate.
SDOperand RHSShift; // The shift.
SDOperand RHSMask; // AND value if any.
if (!MatchRotateHalf(RHS, RHSShift, RHSMask))
return 0; // Not part of a rotate.
if (LHSShift.getOperand(0) != RHSShift.getOperand(0))
return 0; // Not shifting the same value.
if (LHSShift.getOpcode() == RHSShift.getOpcode())
return 0; // Shifts must disagree.
// Canonicalize shl to left side in a shl/srl pair.
if (RHSShift.getOpcode() == ISD::SHL) {
std::swap(LHS, RHS);
std::swap(LHSShift, RHSShift);
std::swap(LHSMask , RHSMask );
}
unsigned OpSizeInBits = VT.getSizeInBits();
SDOperand LHSShiftArg = LHSShift.getOperand(0);
SDOperand LHSShiftAmt = LHSShift.getOperand(1);
SDOperand RHSShiftAmt = RHSShift.getOperand(1);
// fold (or (shl x, C1), (srl x, C2)) -> (rotl x, C1)
// fold (or (shl x, C1), (srl x, C2)) -> (rotr x, C2)
if (LHSShiftAmt.getOpcode() == ISD::Constant &&
RHSShiftAmt.getOpcode() == ISD::Constant) {
uint64_t LShVal = cast<ConstantSDNode>(LHSShiftAmt)->getValue();
uint64_t RShVal = cast<ConstantSDNode>(RHSShiftAmt)->getValue();
if ((LShVal + RShVal) != OpSizeInBits)
return 0;
SDOperand Rot;
if (HasROTL)
Rot = DAG.getNode(ISD::ROTL, VT, LHSShiftArg, LHSShiftAmt);
else
Rot = DAG.getNode(ISD::ROTR, VT, LHSShiftArg, RHSShiftAmt);
// If there is an AND of either shifted operand, apply it to the result.
if (LHSMask.Val || RHSMask.Val) {
APInt Mask = APInt::getAllOnesValue(OpSizeInBits);
if (LHSMask.Val) {
APInt RHSBits = APInt::getLowBitsSet(OpSizeInBits, LShVal);
Mask &= cast<ConstantSDNode>(LHSMask)->getAPIntValue() | RHSBits;
}
if (RHSMask.Val) {
APInt LHSBits = APInt::getHighBitsSet(OpSizeInBits, RShVal);
Mask &= cast<ConstantSDNode>(RHSMask)->getAPIntValue() | LHSBits;
}
Rot = DAG.getNode(ISD::AND, VT, Rot, DAG.getConstant(Mask, VT));
}
return Rot.Val;
}
// If there is a mask here, and we have a variable shift, we can't be sure
// that we're masking out the right stuff.
if (LHSMask.Val || RHSMask.Val)
return 0;
// fold (or (shl x, y), (srl x, (sub 32, y))) -> (rotl x, y)
// fold (or (shl x, y), (srl x, (sub 32, y))) -> (rotr x, (sub 32, y))
if (RHSShiftAmt.getOpcode() == ISD::SUB &&
LHSShiftAmt == RHSShiftAmt.getOperand(1)) {
if (ConstantSDNode *SUBC =
dyn_cast<ConstantSDNode>(RHSShiftAmt.getOperand(0))) {
if (SUBC->getAPIntValue() == OpSizeInBits) {
if (HasROTL)
return DAG.getNode(ISD::ROTL, VT, LHSShiftArg, LHSShiftAmt).Val;
else
return DAG.getNode(ISD::ROTR, VT, LHSShiftArg, RHSShiftAmt).Val;
}
}
}
// fold (or (shl x, (sub 32, y)), (srl x, r)) -> (rotr x, y)
// fold (or (shl x, (sub 32, y)), (srl x, r)) -> (rotl x, (sub 32, y))
if (LHSShiftAmt.getOpcode() == ISD::SUB &&
RHSShiftAmt == LHSShiftAmt.getOperand(1)) {
if (ConstantSDNode *SUBC =
dyn_cast<ConstantSDNode>(LHSShiftAmt.getOperand(0))) {
if (SUBC->getAPIntValue() == OpSizeInBits) {
if (HasROTL)
return DAG.getNode(ISD::ROTL, VT, LHSShiftArg, LHSShiftAmt).Val;
else
return DAG.getNode(ISD::ROTR, VT, LHSShiftArg, RHSShiftAmt).Val;
}
}
}
// Look for sign/zext/any-extended cases:
if ((LHSShiftAmt.getOpcode() == ISD::SIGN_EXTEND
|| LHSShiftAmt.getOpcode() == ISD::ZERO_EXTEND
|| LHSShiftAmt.getOpcode() == ISD::ANY_EXTEND) &&
(RHSShiftAmt.getOpcode() == ISD::SIGN_EXTEND
|| RHSShiftAmt.getOpcode() == ISD::ZERO_EXTEND
|| RHSShiftAmt.getOpcode() == ISD::ANY_EXTEND)) {
SDOperand LExtOp0 = LHSShiftAmt.getOperand(0);
SDOperand RExtOp0 = RHSShiftAmt.getOperand(0);
if (RExtOp0.getOpcode() == ISD::SUB &&
RExtOp0.getOperand(1) == LExtOp0) {
// fold (or (shl x, (*ext y)), (srl x, (*ext (sub 32, y)))) ->
// (rotr x, y)
// fold (or (shl x, (*ext y)), (srl x, (*ext (sub 32, y)))) ->
// (rotl x, (sub 32, y))
if (ConstantSDNode *SUBC = cast<ConstantSDNode>(RExtOp0.getOperand(0))) {
if (SUBC->getAPIntValue() == OpSizeInBits) {
if (HasROTL)
return DAG.getNode(ISD::ROTL, VT, LHSShiftArg, LHSShiftAmt).Val;
else
return DAG.getNode(ISD::ROTR, VT, LHSShiftArg, RHSShiftAmt).Val;
}
}
} else if (LExtOp0.getOpcode() == ISD::SUB &&
RExtOp0 == LExtOp0.getOperand(1)) {
// fold (or (shl x, (*ext (sub 32, y))), (srl x, (*ext r))) ->
// (rotl x, y)
// fold (or (shl x, (*ext (sub 32, y))), (srl x, (*ext r))) ->
// (rotr x, (sub 32, y))
if (ConstantSDNode *SUBC = cast<ConstantSDNode>(LExtOp0.getOperand(0))) {
if (SUBC->getAPIntValue() == OpSizeInBits) {
if (HasROTL)
return DAG.getNode(ISD::ROTL, VT, LHSShiftArg, RHSShiftAmt).Val;
else
return DAG.getNode(ISD::ROTL, VT, LHSShiftArg, LHSShiftAmt).Val;
}
}
}
}
return 0;
}
SDOperand DAGCombiner::visitXOR(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
SDOperand LHS, RHS, CC;
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
MVT VT = N0.getValueType();
// fold vector ops
if (VT.isVector()) {
SDOperand FoldedVOp = SimplifyVBinOp(N);
if (FoldedVOp.Val) return FoldedVOp;
}
// fold (xor undef, undef) -> 0. This is a common idiom (misuse).
if (N0.getOpcode() == ISD::UNDEF && N1.getOpcode() == ISD::UNDEF)
return DAG.getConstant(0, VT);
// fold (xor x, undef) -> undef
if (N0.getOpcode() == ISD::UNDEF)
return N0;
if (N1.getOpcode() == ISD::UNDEF)
return N1;
// fold (xor c1, c2) -> c1^c2
if (N0C && N1C)
return DAG.getNode(ISD::XOR, VT, N0, N1);
// canonicalize constant to RHS
if (N0C && !N1C)
return DAG.getNode(ISD::XOR, VT, N1, N0);
// fold (xor x, 0) -> x
if (N1C && N1C->isNullValue())
return N0;
// reassociate xor
SDOperand RXOR = ReassociateOps(ISD::XOR, N0, N1);
if (RXOR.Val != 0)
return RXOR;
// fold !(x cc y) -> (x !cc y)
if (N1C && N1C->getAPIntValue() == 1 && isSetCCEquivalent(N0, LHS, RHS, CC)) {
bool isInt = LHS.getValueType().isInteger();
ISD::CondCode NotCC = ISD::getSetCCInverse(cast<CondCodeSDNode>(CC)->get(),
isInt);
if (N0.getOpcode() == ISD::SETCC)
return DAG.getSetCC(VT, LHS, RHS, NotCC);
if (N0.getOpcode() == ISD::SELECT_CC)
return DAG.getSelectCC(LHS, RHS, N0.getOperand(2),N0.getOperand(3),NotCC);
assert(0 && "Unhandled SetCC Equivalent!");
abort();
}
// fold (not (zext (setcc x, y))) -> (zext (not (setcc x, y)))
if (N1C && N1C->getAPIntValue() == 1 && N0.getOpcode() == ISD::ZERO_EXTEND &&
N0.Val->hasOneUse() && isSetCCEquivalent(N0.getOperand(0), LHS, RHS, CC)){
SDOperand V = N0.getOperand(0);
V = DAG.getNode(ISD::XOR, V.getValueType(), V,
DAG.getConstant(1, V.getValueType()));
AddToWorkList(V.Val);
return DAG.getNode(ISD::ZERO_EXTEND, VT, V);
}
// fold !(x or y) -> (!x and !y) iff x or y are setcc
if (N1C && N1C->getAPIntValue() == 1 && VT == MVT::i1 &&
(N0.getOpcode() == ISD::OR || N0.getOpcode() == ISD::AND)) {
SDOperand LHS = N0.getOperand(0), RHS = N0.getOperand(1);
if (isOneUseSetCC(RHS) || isOneUseSetCC(LHS)) {
unsigned NewOpcode = N0.getOpcode() == ISD::AND ? ISD::OR : ISD::AND;
LHS = DAG.getNode(ISD::XOR, VT, LHS, N1); // RHS = ~LHS
RHS = DAG.getNode(ISD::XOR, VT, RHS, N1); // RHS = ~RHS
AddToWorkList(LHS.Val); AddToWorkList(RHS.Val);
return DAG.getNode(NewOpcode, VT, LHS, RHS);
}
}
// fold !(x or y) -> (!x and !y) iff x or y are constants
if (N1C && N1C->isAllOnesValue() &&
(N0.getOpcode() == ISD::OR || N0.getOpcode() == ISD::AND)) {
SDOperand LHS = N0.getOperand(0), RHS = N0.getOperand(1);
if (isa<ConstantSDNode>(RHS) || isa<ConstantSDNode>(LHS)) {
unsigned NewOpcode = N0.getOpcode() == ISD::AND ? ISD::OR : ISD::AND;
LHS = DAG.getNode(ISD::XOR, VT, LHS, N1); // RHS = ~LHS
RHS = DAG.getNode(ISD::XOR, VT, RHS, N1); // RHS = ~RHS
AddToWorkList(LHS.Val); AddToWorkList(RHS.Val);
return DAG.getNode(NewOpcode, VT, LHS, RHS);
}
}
// fold (xor (xor x, c1), c2) -> (xor x, c1^c2)
if (N1C && N0.getOpcode() == ISD::XOR) {
ConstantSDNode *N00C = dyn_cast<ConstantSDNode>(N0.getOperand(0));
ConstantSDNode *N01C = dyn_cast<ConstantSDNode>(N0.getOperand(1));
if (N00C)
return DAG.getNode(ISD::XOR, VT, N0.getOperand(1),
DAG.getConstant(N1C->getAPIntValue()^
N00C->getAPIntValue(), VT));
if (N01C)
return DAG.getNode(ISD::XOR, VT, N0.getOperand(0),
DAG.getConstant(N1C->getAPIntValue()^
N01C->getAPIntValue(), VT));
}
// fold (xor x, x) -> 0
if (N0 == N1) {
if (!VT.isVector()) {
return DAG.getConstant(0, VT);
} else if (!AfterLegalize || TLI.isOperationLegal(ISD::BUILD_VECTOR, VT)) {
// Produce a vector of zeros.
SDOperand El = DAG.getConstant(0, VT.getVectorElementType());
std::vector<SDOperand> Ops(VT.getVectorNumElements(), El);
return DAG.getNode(ISD::BUILD_VECTOR, VT, &Ops[0], Ops.size());
}
}
// Simplify: xor (op x...), (op y...) -> (op (xor x, y))
if (N0.getOpcode() == N1.getOpcode()) {
SDOperand Tmp = SimplifyBinOpWithSameOpcodeHands(N);
if (Tmp.Val) return Tmp;
}
// Simplify the expression using non-local knowledge.
if (!VT.isVector() &&
SimplifyDemandedBits(SDOperand(N, 0)))
return SDOperand(N, 0);
return SDOperand();
}
/// visitShiftByConstant - Handle transforms common to the three shifts, when
/// the shift amount is a constant.
SDOperand DAGCombiner::visitShiftByConstant(SDNode *N, unsigned Amt) {
SDNode *LHS = N->getOperand(0).Val;
if (!LHS->hasOneUse()) return SDOperand();
// We want to pull some binops through shifts, so that we have (and (shift))
// instead of (shift (and)), likewise for add, or, xor, etc. This sort of
// thing happens with address calculations, so it's important to canonicalize
// it.
bool HighBitSet = false; // Can we transform this if the high bit is set?
switch (LHS->getOpcode()) {
default: return SDOperand();
case ISD::OR:
case ISD::XOR:
HighBitSet = false; // We can only transform sra if the high bit is clear.
break;
case ISD::AND:
HighBitSet = true; // We can only transform sra if the high bit is set.
break;
case ISD::ADD:
if (N->getOpcode() != ISD::SHL)
return SDOperand(); // only shl(add) not sr[al](add).
HighBitSet = false; // We can only transform sra if the high bit is clear.
break;
}
// We require the RHS of the binop to be a constant as well.
ConstantSDNode *BinOpCst = dyn_cast<ConstantSDNode>(LHS->getOperand(1));
if (!BinOpCst) return SDOperand();
// FIXME: disable this for unless the input to the binop is a shift by a
// constant. If it is not a shift, it pessimizes some common cases like:
//
//void foo(int *X, int i) { X[i & 1235] = 1; }
//int bar(int *X, int i) { return X[i & 255]; }
SDNode *BinOpLHSVal = LHS->getOperand(0).Val;
if ((BinOpLHSVal->getOpcode() != ISD::SHL &&
BinOpLHSVal->getOpcode() != ISD::SRA &&
BinOpLHSVal->getOpcode() != ISD::SRL) ||
!isa<ConstantSDNode>(BinOpLHSVal->getOperand(1)))
return SDOperand();
MVT VT = N->getValueType(0);
// If this is a signed shift right, and the high bit is modified
// by the logical operation, do not perform the transformation.
// The highBitSet boolean indicates the value of the high bit of
// the constant which would cause it to be modified for this
// operation.
if (N->getOpcode() == ISD::SRA) {
bool BinOpRHSSignSet = BinOpCst->getAPIntValue().isNegative();
if (BinOpRHSSignSet != HighBitSet)
return SDOperand();
}
// Fold the constants, shifting the binop RHS by the shift amount.
SDOperand NewRHS = DAG.getNode(N->getOpcode(), N->getValueType(0),
LHS->getOperand(1), N->getOperand(1));
// Create the new shift.
SDOperand NewShift = DAG.getNode(N->getOpcode(), VT, LHS->getOperand(0),
N->getOperand(1));
// Create the new binop.
return DAG.getNode(LHS->getOpcode(), VT, NewShift, NewRHS);
}
SDOperand DAGCombiner::visitSHL(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
MVT VT = N0.getValueType();
unsigned OpSizeInBits = VT.getSizeInBits();
// fold (shl c1, c2) -> c1<<c2
if (N0C && N1C)
return DAG.getNode(ISD::SHL, VT, N0, N1);
// fold (shl 0, x) -> 0
if (N0C && N0C->isNullValue())
return N0;
// fold (shl x, c >= size(x)) -> undef
if (N1C && N1C->getValue() >= OpSizeInBits)
return DAG.getNode(ISD::UNDEF, VT);
// fold (shl x, 0) -> x
if (N1C && N1C->isNullValue())
return N0;
// if (shl x, c) is known to be zero, return 0
if (DAG.MaskedValueIsZero(SDOperand(N, 0),
APInt::getAllOnesValue(VT.getSizeInBits())))
return DAG.getConstant(0, VT);
if (N1C && SimplifyDemandedBits(SDOperand(N, 0)))
return SDOperand(N, 0);
// fold (shl (shl x, c1), c2) -> 0 or (shl x, c1+c2)
if (N1C && N0.getOpcode() == ISD::SHL &&
N0.getOperand(1).getOpcode() == ISD::Constant) {
uint64_t c1 = cast<ConstantSDNode>(N0.getOperand(1))->getValue();
uint64_t c2 = N1C->getValue();
if (c1 + c2 > OpSizeInBits)
return DAG.getConstant(0, VT);
return DAG.getNode(ISD::SHL, VT, N0.getOperand(0),
DAG.getConstant(c1 + c2, N1.getValueType()));
}
// fold (shl (srl x, c1), c2) -> (shl (and x, -1 << c1), c2-c1) or
// (srl (and x, -1 << c1), c1-c2)
if (N1C && N0.getOpcode() == ISD::SRL &&
N0.getOperand(1).getOpcode() == ISD::Constant) {
uint64_t c1 = cast<ConstantSDNode>(N0.getOperand(1))->getValue();
uint64_t c2 = N1C->getValue();
SDOperand Mask = DAG.getNode(ISD::AND, VT, N0.getOperand(0),
DAG.getConstant(~0ULL << c1, VT));
if (c2 > c1)
return DAG.getNode(ISD::SHL, VT, Mask,
DAG.getConstant(c2-c1, N1.getValueType()));
else
return DAG.getNode(ISD::SRL, VT, Mask,
DAG.getConstant(c1-c2, N1.getValueType()));
}
// fold (shl (sra x, c1), c1) -> (and x, -1 << c1)
if (N1C && N0.getOpcode() == ISD::SRA && N1 == N0.getOperand(1))
return DAG.getNode(ISD::AND, VT, N0.getOperand(0),
DAG.getConstant(~0ULL << N1C->getValue(), VT));
return N1C ? visitShiftByConstant(N, N1C->getValue()) : SDOperand();
}
SDOperand DAGCombiner::visitSRA(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
MVT VT = N0.getValueType();
// fold (sra c1, c2) -> c1>>c2
if (N0C && N1C)
return DAG.getNode(ISD::SRA, VT, N0, N1);
// fold (sra 0, x) -> 0
if (N0C && N0C->isNullValue())
return N0;
// fold (sra -1, x) -> -1
if (N0C && N0C->isAllOnesValue())
return N0;
// fold (sra x, c >= size(x)) -> undef
if (N1C && N1C->getValue() >= VT.getSizeInBits())
return DAG.getNode(ISD::UNDEF, VT);
// fold (sra x, 0) -> x
if (N1C && N1C->isNullValue())
return N0;
// fold (sra (shl x, c1), c1) -> sext_inreg for some c1 and target supports
// sext_inreg.
if (N1C && N0.getOpcode() == ISD::SHL && N1 == N0.getOperand(1)) {
unsigned LowBits = VT.getSizeInBits() - (unsigned)N1C->getValue();
MVT EVT = MVT::getIntegerVT(LowBits);
if (EVT.isSimple() && // TODO: remove when apint codegen support lands.
(!AfterLegalize || TLI.isOperationLegal(ISD::SIGN_EXTEND_INREG, EVT)))
return DAG.getNode(ISD::SIGN_EXTEND_INREG, VT, N0.getOperand(0),
DAG.getValueType(EVT));
}
// fold (sra (sra x, c1), c2) -> (sra x, c1+c2)
if (N1C && N0.getOpcode() == ISD::SRA) {
if (ConstantSDNode *C1 = dyn_cast<ConstantSDNode>(N0.getOperand(1))) {
unsigned Sum = N1C->getValue() + C1->getValue();
if (Sum >= VT.getSizeInBits()) Sum = VT.getSizeInBits()-1;
return DAG.getNode(ISD::SRA, VT, N0.getOperand(0),
DAG.getConstant(Sum, N1C->getValueType(0)));
}
}
// fold sra (shl X, m), result_size - n
// -> (sign_extend (trunc (shl X, result_size - n - m))) for
// result_size - n != m.
// If truncate is free for the target sext(shl) is likely to result in better
// code.
if (N0.getOpcode() == ISD::SHL) {
// Get the two constanst of the shifts, CN0 = m, CN = n.
const ConstantSDNode *N01C = dyn_cast<ConstantSDNode>(N0.getOperand(1));
if (N01C && N1C) {
// Determine what the truncate's result bitsize and type would be.
unsigned VTValSize = VT.getSizeInBits();
MVT TruncVT =
MVT::getIntegerVT(VTValSize - N1C->getValue());
// Determine the residual right-shift amount.
unsigned ShiftAmt = N1C->getValue() - N01C->getValue();
// If the shift is not a no-op (in which case this should be just a sign
// extend already), the truncated to type is legal, sign_extend is legal
// on that type, and the the truncate to that type is both legal and free,
// perform the transform.
if (ShiftAmt &&
TLI.isOperationLegal(ISD::SIGN_EXTEND, TruncVT) &&
TLI.isOperationLegal(ISD::TRUNCATE, VT) &&
TLI.isTruncateFree(VT, TruncVT)) {
SDOperand Amt = DAG.getConstant(ShiftAmt, TLI.getShiftAmountTy());
SDOperand Shift = DAG.getNode(ISD::SRL, VT, N0.getOperand(0), Amt);
SDOperand Trunc = DAG.getNode(ISD::TRUNCATE, TruncVT, Shift);
return DAG.getNode(ISD::SIGN_EXTEND, N->getValueType(0), Trunc);
}
}
}
// Simplify, based on bits shifted out of the LHS.
if (N1C && SimplifyDemandedBits(SDOperand(N, 0)))
return SDOperand(N, 0);
// If the sign bit is known to be zero, switch this to a SRL.
if (DAG.SignBitIsZero(N0))
return DAG.getNode(ISD::SRL, VT, N0, N1);
return N1C ? visitShiftByConstant(N, N1C->getValue()) : SDOperand();
}
SDOperand DAGCombiner::visitSRL(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
MVT VT = N0.getValueType();
unsigned OpSizeInBits = VT.getSizeInBits();
// fold (srl c1, c2) -> c1 >>u c2
if (N0C && N1C)
return DAG.getNode(ISD::SRL, VT, N0, N1);
// fold (srl 0, x) -> 0
if (N0C && N0C->isNullValue())
return N0;
// fold (srl x, c >= size(x)) -> undef
if (N1C && N1C->getValue() >= OpSizeInBits)
return DAG.getNode(ISD::UNDEF, VT);
// fold (srl x, 0) -> x
if (N1C && N1C->isNullValue())
return N0;
// if (srl x, c) is known to be zero, return 0
if (N1C && DAG.MaskedValueIsZero(SDOperand(N, 0),
APInt::getAllOnesValue(OpSizeInBits)))
return DAG.getConstant(0, VT);
// fold (srl (srl x, c1), c2) -> 0 or (srl x, c1+c2)
if (N1C && N0.getOpcode() == ISD::SRL &&
N0.getOperand(1).getOpcode() == ISD::Constant) {
uint64_t c1 = cast<ConstantSDNode>(N0.getOperand(1))->getValue();
uint64_t c2 = N1C->getValue();
if (c1 + c2 > OpSizeInBits)
return DAG.getConstant(0, VT);
return DAG.getNode(ISD::SRL, VT, N0.getOperand(0),
DAG.getConstant(c1 + c2, N1.getValueType()));
}
// fold (srl (anyextend x), c) -> (anyextend (srl x, c))
if (N1C && N0.getOpcode() == ISD::ANY_EXTEND) {
// Shifting in all undef bits?
MVT SmallVT = N0.getOperand(0).getValueType();
if (N1C->getValue() >= SmallVT.getSizeInBits())
return DAG.getNode(ISD::UNDEF, VT);
SDOperand SmallShift = DAG.getNode(ISD::SRL, SmallVT, N0.getOperand(0), N1);
AddToWorkList(SmallShift.Val);
return DAG.getNode(ISD::ANY_EXTEND, VT, SmallShift);
}
// fold (srl (sra X, Y), 31) -> (srl X, 31). This srl only looks at the sign
// bit, which is unmodified by sra.
if (N1C && N1C->getValue()+1 == VT.getSizeInBits()) {
if (N0.getOpcode() == ISD::SRA)
return DAG.getNode(ISD::SRL, VT, N0.getOperand(0), N1);
}
// fold (srl (ctlz x), "5") -> x iff x has one bit set (the low bit).
if (N1C && N0.getOpcode() == ISD::CTLZ &&
N1C->getAPIntValue() == Log2_32(VT.getSizeInBits())) {
APInt KnownZero, KnownOne;
APInt Mask = APInt::getAllOnesValue(VT.getSizeInBits());
DAG.ComputeMaskedBits(N0.getOperand(0), Mask, KnownZero, KnownOne);
// If any of the input bits are KnownOne, then the input couldn't be all
// zeros, thus the result of the srl will always be zero.
if (KnownOne.getBoolValue()) return DAG.getConstant(0, VT);
// If all of the bits input the to ctlz node are known to be zero, then
// the result of the ctlz is "32" and the result of the shift is one.
APInt UnknownBits = ~KnownZero & Mask;
if (UnknownBits == 0) return DAG.getConstant(1, VT);
// Otherwise, check to see if there is exactly one bit input to the ctlz.
if ((UnknownBits & (UnknownBits-1)) == 0) {
// Okay, we know that only that the single bit specified by UnknownBits
// could be set on input to the CTLZ node. If this bit is set, the SRL
// will return 0, if it is clear, it returns 1. Change the CTLZ/SRL pair
// to an SRL,XOR pair, which is likely to simplify more.
unsigned ShAmt = UnknownBits.countTrailingZeros();
SDOperand Op = N0.getOperand(0);
if (ShAmt) {
Op = DAG.getNode(ISD::SRL, VT, Op,
DAG.getConstant(ShAmt, TLI.getShiftAmountTy()));
AddToWorkList(Op.Val);
}
return DAG.getNode(ISD::XOR, VT, Op, DAG.getConstant(1, VT));
}
}
// fold operands of srl based on knowledge that the low bits are not
// demanded.
if (N1C && SimplifyDemandedBits(SDOperand(N, 0)))
return SDOperand(N, 0);
return N1C ? visitShiftByConstant(N, N1C->getValue()) : SDOperand();
}
SDOperand DAGCombiner::visitCTLZ(SDNode *N) {
SDOperand N0 = N->getOperand(0);
MVT VT = N->getValueType(0);
// fold (ctlz c1) -> c2
if (isa<ConstantSDNode>(N0))
return DAG.getNode(ISD::CTLZ, VT, N0);
return SDOperand();
}
SDOperand DAGCombiner::visitCTTZ(SDNode *N) {
SDOperand N0 = N->getOperand(0);
MVT VT = N->getValueType(0);
// fold (cttz c1) -> c2
if (isa<ConstantSDNode>(N0))
return DAG.getNode(ISD::CTTZ, VT, N0);
return SDOperand();
}
SDOperand DAGCombiner::visitCTPOP(SDNode *N) {
SDOperand N0 = N->getOperand(0);
MVT VT = N->getValueType(0);
// fold (ctpop c1) -> c2
if (isa<ConstantSDNode>(N0))
return DAG.getNode(ISD::CTPOP, VT, N0);
return SDOperand();
}
SDOperand DAGCombiner::visitSELECT(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
SDOperand N2 = N->getOperand(2);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
ConstantSDNode *N2C = dyn_cast<ConstantSDNode>(N2);
MVT VT = N->getValueType(0);
MVT VT0 = N0.getValueType();
// fold select C, X, X -> X
if (N1 == N2)
return N1;
// fold select true, X, Y -> X
if (N0C && !N0C->isNullValue())
return N1;
// fold select false, X, Y -> Y
if (N0C && N0C->isNullValue())
return N2;
// fold select C, 1, X -> C | X
if (VT == MVT::i1 && N1C && N1C->getAPIntValue() == 1)
return DAG.getNode(ISD::OR, VT, N0, N2);
// fold select C, 0, 1 -> ~C
if (VT.isInteger() && VT0.isInteger() &&
N1C && N2C && N1C->isNullValue() && N2C->getAPIntValue() == 1) {
SDOperand XORNode = DAG.getNode(ISD::XOR, VT0, N0, DAG.getConstant(1, VT0));
if (VT == VT0)
return XORNode;
AddToWorkList(XORNode.Val);
if (VT.bitsGT(VT0))
return DAG.getNode(ISD::ZERO_EXTEND, VT, XORNode);
return DAG.getNode(ISD::TRUNCATE, VT, XORNode);
}
// fold select C, 0, X -> ~C & X
if (VT == VT0 && VT == MVT::i1 && N1C && N1C->isNullValue()) {
SDOperand XORNode = DAG.getNode(ISD::XOR, VT, N0, DAG.getConstant(1, VT));
AddToWorkList(XORNode.Val);
return DAG.getNode(ISD::AND, VT, XORNode, N2);
}
// fold select C, X, 1 -> ~C | X
if (VT == VT0 && VT == MVT::i1 && N2C && N2C->getAPIntValue() == 1) {
SDOperand XORNode = DAG.getNode(ISD::XOR, VT, N0, DAG.getConstant(1, VT));
AddToWorkList(XORNode.Val);
return DAG.getNode(ISD::OR, VT, XORNode, N1);
}
// fold select C, X, 0 -> C & X
// FIXME: this should check for C type == X type, not i1?
if (VT == MVT::i1 && N2C && N2C->isNullValue())
return DAG.getNode(ISD::AND, VT, N0, N1);
// fold X ? X : Y --> X ? 1 : Y --> X | Y
if (VT == MVT::i1 && N0 == N1)
return DAG.getNode(ISD::OR, VT, N0, N2);
// fold X ? Y : X --> X ? Y : 0 --> X & Y
if (VT == MVT::i1 && N0 == N2)
return DAG.getNode(ISD::AND, VT, N0, N1);
// If we can fold this based on the true/false value, do so.
if (SimplifySelectOps(N, N1, N2))
return SDOperand(N, 0); // Don't revisit N.
// fold selects based on a setcc into other things, such as min/max/abs
if (N0.getOpcode() == ISD::SETCC) {
// FIXME:
// Check against MVT::Other for SELECT_CC, which is a workaround for targets
// having to say they don't support SELECT_CC on every type the DAG knows
// about, since there is no way to mark an opcode illegal at all value types
if (TLI.isOperationLegal(ISD::SELECT_CC, MVT::Other))
return DAG.getNode(ISD::SELECT_CC, VT, N0.getOperand(0), N0.getOperand(1),
N1, N2, N0.getOperand(2));
else
return SimplifySelect(N0, N1, N2);
}
return SDOperand();
}
SDOperand DAGCombiner::visitSELECT_CC(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
SDOperand N2 = N->getOperand(2);
SDOperand N3 = N->getOperand(3);
SDOperand N4 = N->getOperand(4);
ISD::CondCode CC = cast<CondCodeSDNode>(N4)->get();
// fold select_cc lhs, rhs, x, x, cc -> x
if (N2 == N3)
return N2;
// Determine if the condition we're dealing with is constant
SDOperand SCC = SimplifySetCC(TLI.getSetCCResultType(N0), N0, N1, CC, false);
if (SCC.Val) AddToWorkList(SCC.Val);
if (ConstantSDNode *SCCC = dyn_cast_or_null<ConstantSDNode>(SCC.Val)) {
if (!SCCC->isNullValue())
return N2; // cond always true -> true val
else
return N3; // cond always false -> false val
}
// Fold to a simpler select_cc
if (SCC.Val && SCC.getOpcode() == ISD::SETCC)
return DAG.getNode(ISD::SELECT_CC, N2.getValueType(),
SCC.getOperand(0), SCC.getOperand(1), N2, N3,
SCC.getOperand(2));
// If we can fold this based on the true/false value, do so.
if (SimplifySelectOps(N, N2, N3))
return SDOperand(N, 0); // Don't revisit N.
// fold select_cc into other things, such as min/max/abs
return SimplifySelectCC(N0, N1, N2, N3, CC);
}
SDOperand DAGCombiner::visitSETCC(SDNode *N) {
return SimplifySetCC(N->getValueType(0), N->getOperand(0), N->getOperand(1),
cast<CondCodeSDNode>(N->getOperand(2))->get());
}
// ExtendUsesToFormExtLoad - Trying to extend uses of a load to enable this:
// "fold ({s|z}ext (load x)) -> ({s|z}ext (truncate ({s|z}extload x)))"
// transformation. Returns true if extension are possible and the above
// mentioned transformation is profitable.
static bool ExtendUsesToFormExtLoad(SDNode *N, SDOperand N0,
unsigned ExtOpc,
SmallVector<SDNode*, 4> &ExtendNodes,
TargetLowering &TLI) {
bool HasCopyToRegUses = false;
bool isTruncFree = TLI.isTruncateFree(N->getValueType(0), N0.getValueType());
for (SDNode::use_iterator UI = N0.Val->use_begin(), UE = N0.Val->use_end();
UI != UE; ++UI) {
SDNode *User = UI->getUser();
if (User == N)
continue;
// FIXME: Only extend SETCC N, N and SETCC N, c for now.
if (User->getOpcode() == ISD::SETCC) {
ISD::CondCode CC = cast<CondCodeSDNode>(User->getOperand(2))->get();
if (ExtOpc == ISD::ZERO_EXTEND && ISD::isSignedIntSetCC(CC))
// Sign bits will be lost after a zext.
return false;
bool Add = false;
for (unsigned i = 0; i != 2; ++i) {
SDOperand UseOp = User->getOperand(i);
if (UseOp == N0)
continue;
if (!isa<ConstantSDNode>(UseOp))
return false;
Add = true;
}
if (Add)
ExtendNodes.push_back(User);
} else {
for (unsigned i = 0, e = User->getNumOperands(); i != e; ++i) {
SDOperand UseOp = User->getOperand(i);
if (UseOp == N0) {
// If truncate from extended type to original load type is free
// on this target, then it's ok to extend a CopyToReg.
if (isTruncFree && User->getOpcode() == ISD::CopyToReg)
HasCopyToRegUses = true;
else
return false;
}
}
}
}
if (HasCopyToRegUses) {
bool BothLiveOut = false;
for (SDNode::use_iterator UI = N->use_begin(), UE = N->use_end();
UI != UE; ++UI) {
SDNode *User = UI->getUser();
for (unsigned i = 0, e = User->getNumOperands(); i != e; ++i) {
SDOperand UseOp = User->getOperand(i);
if (UseOp.Val == N && UseOp.ResNo == 0) {
BothLiveOut = true;
break;
}
}
}
if (BothLiveOut)
// Both unextended and extended values are live out. There had better be
// good a reason for the transformation.
return ExtendNodes.size();
}
return true;
}
SDOperand DAGCombiner::visitSIGN_EXTEND(SDNode *N) {
SDOperand N0 = N->getOperand(0);
MVT VT = N->getValueType(0);
// fold (sext c1) -> c1
if (isa<ConstantSDNode>(N0))
return DAG.getNode(ISD::SIGN_EXTEND, VT, N0);
// fold (sext (sext x)) -> (sext x)
// fold (sext (aext x)) -> (sext x)
if (N0.getOpcode() == ISD::SIGN_EXTEND || N0.getOpcode() == ISD::ANY_EXTEND)
return DAG.getNode(ISD::SIGN_EXTEND, VT, N0.getOperand(0));
if (N0.getOpcode() == ISD::TRUNCATE) {
// fold (sext (truncate (load x))) -> (sext (smaller load x))
// fold (sext (truncate (srl (load x), c))) -> (sext (smaller load (x+c/n)))
SDOperand NarrowLoad = ReduceLoadWidth(N0.Val);
if (NarrowLoad.Val) {
if (NarrowLoad.Val != N0.Val)
CombineTo(N0.Val, NarrowLoad);
return DAG.getNode(ISD::SIGN_EXTEND, VT, NarrowLoad);
}
// See if the value being truncated is already sign extended. If so, just
// eliminate the trunc/sext pair.
SDOperand Op = N0.getOperand(0);
unsigned OpBits = Op.getValueType().getSizeInBits();
unsigned MidBits = N0.getValueType().getSizeInBits();
unsigned DestBits = VT.getSizeInBits();
unsigned NumSignBits = DAG.ComputeNumSignBits(Op);
if (OpBits == DestBits) {
// Op is i32, Mid is i8, and Dest is i32. If Op has more than 24 sign
// bits, it is already ready.
if (NumSignBits > DestBits-MidBits)
return Op;
} else if (OpBits < DestBits) {
// Op is i32, Mid is i8, and Dest is i64. If Op has more than 24 sign
// bits, just sext from i32.
if (NumSignBits > OpBits-MidBits)
return DAG.getNode(ISD::SIGN_EXTEND, VT, Op);
} else {
// Op is i64, Mid is i8, and Dest is i32. If Op has more than 56 sign
// bits, just truncate to i32.
if (NumSignBits > OpBits-MidBits)
return DAG.getNode(ISD::TRUNCATE, VT, Op);
}
// fold (sext (truncate x)) -> (sextinreg x).
if (!AfterLegalize || TLI.isOperationLegal(ISD::SIGN_EXTEND_INREG,
N0.getValueType())) {
if (Op.getValueType().bitsLT(VT))
Op = DAG.getNode(ISD::ANY_EXTEND, VT, Op);
else if (Op.getValueType().bitsGT(VT))
Op = DAG.getNode(ISD::TRUNCATE, VT, Op);
return DAG.getNode(ISD::SIGN_EXTEND_INREG, VT, Op,
DAG.getValueType(N0.getValueType()));
}
}
// fold (sext (load x)) -> (sext (truncate (sextload x)))
if (ISD::isNON_EXTLoad(N0.Val) &&
((!AfterLegalize && !cast<LoadSDNode>(N0)->isVolatile()) ||
TLI.isLoadXLegal(ISD::SEXTLOAD, N0.getValueType()))) {
bool DoXform = true;
SmallVector<SDNode*, 4> SetCCs;
if (!N0.hasOneUse())
DoXform = ExtendUsesToFormExtLoad(N, N0, ISD::SIGN_EXTEND, SetCCs, TLI);
if (DoXform) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
SDOperand ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, VT, LN0->getChain(),
LN0->getBasePtr(), LN0->getSrcValue(),
LN0->getSrcValueOffset(),
N0.getValueType(),
LN0->isVolatile(),
LN0->getAlignment());
CombineTo(N, ExtLoad);
SDOperand Trunc = DAG.getNode(ISD::TRUNCATE, N0.getValueType(), ExtLoad);
CombineTo(N0.Val, Trunc, ExtLoad.getValue(1));
// Extend SetCC uses if necessary.
for (unsigned i = 0, e = SetCCs.size(); i != e; ++i) {
SDNode *SetCC = SetCCs[i];
SmallVector<SDOperand, 4> Ops;
for (unsigned j = 0; j != 2; ++j) {
SDOperand SOp = SetCC->getOperand(j);
if (SOp == Trunc)
Ops.push_back(ExtLoad);
else
Ops.push_back(DAG.getNode(ISD::SIGN_EXTEND, VT, SOp));
}
Ops.push_back(SetCC->getOperand(2));
CombineTo(SetCC, DAG.getNode(ISD::SETCC, SetCC->getValueType(0),
&Ops[0], Ops.size()));
}
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
}
// fold (sext (sextload x)) -> (sext (truncate (sextload x)))
// fold (sext ( extload x)) -> (sext (truncate (sextload x)))
if ((ISD::isSEXTLoad(N0.Val) || ISD::isEXTLoad(N0.Val)) &&
ISD::isUNINDEXEDLoad(N0.Val) && N0.hasOneUse()) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
MVT EVT = LN0->getMemoryVT();
if ((!AfterLegalize && !LN0->isVolatile()) ||
TLI.isLoadXLegal(ISD::SEXTLOAD, EVT)) {
SDOperand ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, VT, LN0->getChain(),
LN0->getBasePtr(), LN0->getSrcValue(),
LN0->getSrcValueOffset(), EVT,
LN0->isVolatile(),
LN0->getAlignment());
CombineTo(N, ExtLoad);
CombineTo(N0.Val, DAG.getNode(ISD::TRUNCATE, N0.getValueType(), ExtLoad),
ExtLoad.getValue(1));
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
}
// sext(setcc x,y,cc) -> select_cc x, y, -1, 0, cc
if (N0.getOpcode() == ISD::SETCC) {
SDOperand SCC =
SimplifySelectCC(N0.getOperand(0), N0.getOperand(1),
DAG.getConstant(~0ULL, VT), DAG.getConstant(0, VT),
cast<CondCodeSDNode>(N0.getOperand(2))->get(), true);
if (SCC.Val) return SCC;
}
// fold (sext x) -> (zext x) if the sign bit is known zero.
if ((!AfterLegalize || TLI.isOperationLegal(ISD::ZERO_EXTEND, VT)) &&
DAG.SignBitIsZero(N0))
return DAG.getNode(ISD::ZERO_EXTEND, VT, N0);
return SDOperand();
}
SDOperand DAGCombiner::visitZERO_EXTEND(SDNode *N) {
SDOperand N0 = N->getOperand(0);
MVT VT = N->getValueType(0);
// fold (zext c1) -> c1
if (isa<ConstantSDNode>(N0))
return DAG.getNode(ISD::ZERO_EXTEND, VT, N0);
// fold (zext (zext x)) -> (zext x)
// fold (zext (aext x)) -> (zext x)
if (N0.getOpcode() == ISD::ZERO_EXTEND || N0.getOpcode() == ISD::ANY_EXTEND)
return DAG.getNode(ISD::ZERO_EXTEND, VT, N0.getOperand(0));
// fold (zext (truncate (load x))) -> (zext (smaller load x))
// fold (zext (truncate (srl (load x), c))) -> (zext (small load (x+c/n)))
if (N0.getOpcode() == ISD::TRUNCATE) {
SDOperand NarrowLoad = ReduceLoadWidth(N0.Val);
if (NarrowLoad.Val) {
if (NarrowLoad.Val != N0.Val)
CombineTo(N0.Val, NarrowLoad);
return DAG.getNode(ISD::ZERO_EXTEND, VT, NarrowLoad);
}
}
// fold (zext (truncate x)) -> (and x, mask)
if (N0.getOpcode() == ISD::TRUNCATE &&
(!AfterLegalize || TLI.isOperationLegal(ISD::AND, VT))) {
SDOperand Op = N0.getOperand(0);
if (Op.getValueType().bitsLT(VT)) {
Op = DAG.getNode(ISD::ANY_EXTEND, VT, Op);
} else if (Op.getValueType().bitsGT(VT)) {
Op = DAG.getNode(ISD::TRUNCATE, VT, Op);
}
return DAG.getZeroExtendInReg(Op, N0.getValueType());
}
// fold (zext (and (trunc x), cst)) -> (and x, cst).
if (N0.getOpcode() == ISD::AND &&
N0.getOperand(0).getOpcode() == ISD::TRUNCATE &&
N0.getOperand(1).getOpcode() == ISD::Constant) {
SDOperand X = N0.getOperand(0).getOperand(0);
if (X.getValueType().bitsLT(VT)) {
X = DAG.getNode(ISD::ANY_EXTEND, VT, X);
} else if (X.getValueType().bitsGT(VT)) {
X = DAG.getNode(ISD::TRUNCATE, VT, X);
}
APInt Mask = cast<ConstantSDNode>(N0.getOperand(1))->getAPIntValue();
Mask.zext(VT.getSizeInBits());
return DAG.getNode(ISD::AND, VT, X, DAG.getConstant(Mask, VT));
}
// fold (zext (load x)) -> (zext (truncate (zextload x)))
if (ISD::isNON_EXTLoad(N0.Val) &&
((!AfterLegalize && !cast<LoadSDNode>(N0)->isVolatile()) ||
TLI.isLoadXLegal(ISD::ZEXTLOAD, N0.getValueType()))) {
bool DoXform = true;
SmallVector<SDNode*, 4> SetCCs;
if (!N0.hasOneUse())
DoXform = ExtendUsesToFormExtLoad(N, N0, ISD::ZERO_EXTEND, SetCCs, TLI);
if (DoXform) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
SDOperand ExtLoad = DAG.getExtLoad(ISD::ZEXTLOAD, VT, LN0->getChain(),
LN0->getBasePtr(), LN0->getSrcValue(),
LN0->getSrcValueOffset(),
N0.getValueType(),
LN0->isVolatile(),
LN0->getAlignment());
CombineTo(N, ExtLoad);
SDOperand Trunc = DAG.getNode(ISD::TRUNCATE, N0.getValueType(), ExtLoad);
CombineTo(N0.Val, Trunc, ExtLoad.getValue(1));
// Extend SetCC uses if necessary.
for (unsigned i = 0, e = SetCCs.size(); i != e; ++i) {
SDNode *SetCC = SetCCs[i];
SmallVector<SDOperand, 4> Ops;
for (unsigned j = 0; j != 2; ++j) {
SDOperand SOp = SetCC->getOperand(j);
if (SOp == Trunc)
Ops.push_back(ExtLoad);
else
Ops.push_back(DAG.getNode(ISD::ZERO_EXTEND, VT, SOp));
}
Ops.push_back(SetCC->getOperand(2));
CombineTo(SetCC, DAG.getNode(ISD::SETCC, SetCC->getValueType(0),
&Ops[0], Ops.size()));
}
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
}
// fold (zext (zextload x)) -> (zext (truncate (zextload x)))
// fold (zext ( extload x)) -> (zext (truncate (zextload x)))
if ((ISD::isZEXTLoad(N0.Val) || ISD::isEXTLoad(N0.Val)) &&
ISD::isUNINDEXEDLoad(N0.Val) && N0.hasOneUse()) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
MVT EVT = LN0->getMemoryVT();
if ((!AfterLegalize && !LN0->isVolatile()) ||
TLI.isLoadXLegal(ISD::ZEXTLOAD, EVT)) {
SDOperand ExtLoad = DAG.getExtLoad(ISD::ZEXTLOAD, VT, LN0->getChain(),
LN0->getBasePtr(), LN0->getSrcValue(),
LN0->getSrcValueOffset(), EVT,
LN0->isVolatile(),
LN0->getAlignment());
CombineTo(N, ExtLoad);
CombineTo(N0.Val, DAG.getNode(ISD::TRUNCATE, N0.getValueType(), ExtLoad),
ExtLoad.getValue(1));
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
}
// zext(setcc x,y,cc) -> select_cc x, y, 1, 0, cc
if (N0.getOpcode() == ISD::SETCC) {
SDOperand SCC =
SimplifySelectCC(N0.getOperand(0), N0.getOperand(1),
DAG.getConstant(1, VT), DAG.getConstant(0, VT),
cast<CondCodeSDNode>(N0.getOperand(2))->get(), true);
if (SCC.Val) return SCC;
}
return SDOperand();
}
SDOperand DAGCombiner::visitANY_EXTEND(SDNode *N) {
SDOperand N0 = N->getOperand(0);
MVT VT = N->getValueType(0);
// fold (aext c1) -> c1
if (isa<ConstantSDNode>(N0))
return DAG.getNode(ISD::ANY_EXTEND, VT, N0);
// fold (aext (aext x)) -> (aext x)
// fold (aext (zext x)) -> (zext x)
// fold (aext (sext x)) -> (sext x)
if (N0.getOpcode() == ISD::ANY_EXTEND ||
N0.getOpcode() == ISD::ZERO_EXTEND ||
N0.getOpcode() == ISD::SIGN_EXTEND)
return DAG.getNode(N0.getOpcode(), VT, N0.getOperand(0));
// fold (aext (truncate (load x))) -> (aext (smaller load x))
// fold (aext (truncate (srl (load x), c))) -> (aext (small load (x+c/n)))
if (N0.getOpcode() == ISD::TRUNCATE) {
SDOperand NarrowLoad = ReduceLoadWidth(N0.Val);
if (NarrowLoad.Val) {
if (NarrowLoad.Val != N0.Val)
CombineTo(N0.Val, NarrowLoad);
return DAG.getNode(ISD::ANY_EXTEND, VT, NarrowLoad);
}
}
// fold (aext (truncate x))
if (N0.getOpcode() == ISD::TRUNCATE) {
SDOperand TruncOp = N0.getOperand(0);
if (TruncOp.getValueType() == VT)
return TruncOp; // x iff x size == zext size.
if (TruncOp.getValueType().bitsGT(VT))
return DAG.getNode(ISD::TRUNCATE, VT, TruncOp);
return DAG.getNode(ISD::ANY_EXTEND, VT, TruncOp);
}
// fold (aext (and (trunc x), cst)) -> (and x, cst).
if (N0.getOpcode() == ISD::AND &&
N0.getOperand(0).getOpcode() == ISD::TRUNCATE &&
N0.getOperand(1).getOpcode() == ISD::Constant) {
SDOperand X = N0.getOperand(0).getOperand(0);
if (X.getValueType().bitsLT(VT)) {
X = DAG.getNode(ISD::ANY_EXTEND, VT, X);
} else if (X.getValueType().bitsGT(VT)) {
X = DAG.getNode(ISD::TRUNCATE, VT, X);
}
APInt Mask = cast<ConstantSDNode>(N0.getOperand(1))->getAPIntValue();
Mask.zext(VT.getSizeInBits());
return DAG.getNode(ISD::AND, VT, X, DAG.getConstant(Mask, VT));
}
// fold (aext (load x)) -> (aext (truncate (extload x)))
if (ISD::isNON_EXTLoad(N0.Val) && N0.hasOneUse() &&
((!AfterLegalize && !cast<LoadSDNode>(N0)->isVolatile()) ||
TLI.isLoadXLegal(ISD::EXTLOAD, N0.getValueType()))) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
SDOperand ExtLoad = DAG.getExtLoad(ISD::EXTLOAD, VT, LN0->getChain(),
LN0->getBasePtr(), LN0->getSrcValue(),
LN0->getSrcValueOffset(),
N0.getValueType(),
LN0->isVolatile(),
LN0->getAlignment());
CombineTo(N, ExtLoad);
CombineTo(N0.Val, DAG.getNode(ISD::TRUNCATE, N0.getValueType(), ExtLoad),
ExtLoad.getValue(1));
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
// fold (aext (zextload x)) -> (aext (truncate (zextload x)))
// fold (aext (sextload x)) -> (aext (truncate (sextload x)))
// fold (aext ( extload x)) -> (aext (truncate (extload x)))
if (N0.getOpcode() == ISD::LOAD &&
!ISD::isNON_EXTLoad(N0.Val) && ISD::isUNINDEXEDLoad(N0.Val) &&
N0.hasOneUse()) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
MVT EVT = LN0->getMemoryVT();
SDOperand ExtLoad = DAG.getExtLoad(LN0->getExtensionType(), VT,
LN0->getChain(), LN0->getBasePtr(),
LN0->getSrcValue(),
LN0->getSrcValueOffset(), EVT,
LN0->isVolatile(),
LN0->getAlignment());
CombineTo(N, ExtLoad);
CombineTo(N0.Val, DAG.getNode(ISD::TRUNCATE, N0.getValueType(), ExtLoad),
ExtLoad.getValue(1));
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
// aext(setcc x,y,cc) -> select_cc x, y, 1, 0, cc
if (N0.getOpcode() == ISD::SETCC) {
SDOperand SCC =
SimplifySelectCC(N0.getOperand(0), N0.getOperand(1),
DAG.getConstant(1, VT), DAG.getConstant(0, VT),
cast<CondCodeSDNode>(N0.getOperand(2))->get(), true);
if (SCC.Val)
return SCC;
}
return SDOperand();
}
/// GetDemandedBits - See if the specified operand can be simplified with the
/// knowledge that only the bits specified by Mask are used. If so, return the
/// simpler operand, otherwise return a null SDOperand.
SDOperand DAGCombiner::GetDemandedBits(SDOperand V, const APInt &Mask) {
switch (V.getOpcode()) {
default: break;
case ISD::OR:
case ISD::XOR:
// If the LHS or RHS don't contribute bits to the or, drop them.
if (DAG.MaskedValueIsZero(V.getOperand(0), Mask))
return V.getOperand(1);
if (DAG.MaskedValueIsZero(V.getOperand(1), Mask))
return V.getOperand(0);
break;
case ISD::SRL:
// Only look at single-use SRLs.
if (!V.Val->hasOneUse())
break;
if (ConstantSDNode *RHSC = dyn_cast<ConstantSDNode>(V.getOperand(1))) {
// See if we can recursively simplify the LHS.
unsigned Amt = RHSC->getValue();
APInt NewMask = Mask << Amt;
SDOperand SimplifyLHS = GetDemandedBits(V.getOperand(0), NewMask);
if (SimplifyLHS.Val) {
return DAG.getNode(ISD::SRL, V.getValueType(),
SimplifyLHS, V.getOperand(1));
}
}
}
return SDOperand();
}
/// ReduceLoadWidth - If the result of a wider load is shifted to right of N
/// bits and then truncated to a narrower type and where N is a multiple
/// of number of bits of the narrower type, transform it to a narrower load
/// from address + N / num of bits of new type. If the result is to be
/// extended, also fold the extension to form a extending load.
SDOperand DAGCombiner::ReduceLoadWidth(SDNode *N) {
unsigned Opc = N->getOpcode();
ISD::LoadExtType ExtType = ISD::NON_EXTLOAD;
SDOperand N0 = N->getOperand(0);
MVT VT = N->getValueType(0);
MVT EVT = N->getValueType(0);
// Special case: SIGN_EXTEND_INREG is basically truncating to EVT then
// extended to VT.
if (Opc == ISD::SIGN_EXTEND_INREG) {
ExtType = ISD::SEXTLOAD;
EVT = cast<VTSDNode>(N->getOperand(1))->getVT();
if (AfterLegalize && !TLI.isLoadXLegal(ISD::SEXTLOAD, EVT))
return SDOperand();
}
unsigned EVTBits = EVT.getSizeInBits();
unsigned ShAmt = 0;
bool CombineSRL = false;
if (N0.getOpcode() == ISD::SRL && N0.hasOneUse()) {
if (ConstantSDNode *N01 = dyn_cast<ConstantSDNode>(N0.getOperand(1))) {
ShAmt = N01->getValue();
// Is the shift amount a multiple of size of VT?
if ((ShAmt & (EVTBits-1)) == 0) {
N0 = N0.getOperand(0);
if (N0.getValueType().getSizeInBits() <= EVTBits)
return SDOperand();
CombineSRL = true;
}
}
}
// Do not generate loads of non-round integer types since these can
// be expensive (and would be wrong if the type is not byte sized).
if (ISD::isNON_EXTLoad(N0.Val) && N0.hasOneUse() && VT.isRound() &&
// Do not change the width of a volatile load.
!cast<LoadSDNode>(N0)->isVolatile()) {
assert(N0.getValueType().getSizeInBits() > EVTBits &&
"Cannot truncate to larger type!");
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
MVT PtrType = N0.getOperand(1).getValueType();
// For big endian targets, we need to adjust the offset to the pointer to
// load the correct bytes.
if (TLI.isBigEndian()) {
unsigned LVTStoreBits = N0.getValueType().getStoreSizeInBits();
unsigned EVTStoreBits = EVT.getStoreSizeInBits();
ShAmt = LVTStoreBits - EVTStoreBits - ShAmt;
}
uint64_t PtrOff = ShAmt / 8;
unsigned NewAlign = MinAlign(LN0->getAlignment(), PtrOff);
SDOperand NewPtr = DAG.getNode(ISD::ADD, PtrType, LN0->getBasePtr(),
DAG.getConstant(PtrOff, PtrType));
AddToWorkList(NewPtr.Val);
SDOperand Load = (ExtType == ISD::NON_EXTLOAD)
? DAG.getLoad(VT, LN0->getChain(), NewPtr,
LN0->getSrcValue(), LN0->getSrcValueOffset(),
LN0->isVolatile(), NewAlign)
: DAG.getExtLoad(ExtType, VT, LN0->getChain(), NewPtr,
LN0->getSrcValue(), LN0->getSrcValueOffset(), EVT,
LN0->isVolatile(), NewAlign);
AddToWorkList(N);
if (CombineSRL) {
WorkListRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(N0.getValue(1), Load.getValue(1),
&DeadNodes);
CombineTo(N->getOperand(0).Val, Load);
} else
CombineTo(N0.Val, Load, Load.getValue(1));
if (ShAmt) {
if (Opc == ISD::SIGN_EXTEND_INREG)
return DAG.getNode(Opc, VT, Load, N->getOperand(1));
else
return DAG.getNode(Opc, VT, Load);
}
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
return SDOperand();
}
SDOperand DAGCombiner::visitSIGN_EXTEND_INREG(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
MVT VT = N->getValueType(0);
MVT EVT = cast<VTSDNode>(N1)->getVT();
unsigned VTBits = VT.getSizeInBits();
unsigned EVTBits = EVT.getSizeInBits();
// fold (sext_in_reg c1) -> c1
if (isa<ConstantSDNode>(N0) || N0.getOpcode() == ISD::UNDEF)
return DAG.getNode(ISD::SIGN_EXTEND_INREG, VT, N0, N1);
// If the input is already sign extended, just drop the extension.
if (DAG.ComputeNumSignBits(N0) >= VT.getSizeInBits()-EVTBits+1)
return N0;
// fold (sext_in_reg (sext_in_reg x, VT2), VT1) -> (sext_in_reg x, minVT) pt2
if (N0.getOpcode() == ISD::SIGN_EXTEND_INREG &&
EVT.bitsLT(cast<VTSDNode>(N0.getOperand(1))->getVT())) {
return DAG.getNode(ISD::SIGN_EXTEND_INREG, VT, N0.getOperand(0), N1);
}
// fold (sext_in_reg x) -> (zext_in_reg x) if the sign bit is known zero.
if (DAG.MaskedValueIsZero(N0, APInt::getBitsSet(VTBits, EVTBits-1, EVTBits)))
return DAG.getZeroExtendInReg(N0, EVT);
// fold operands of sext_in_reg based on knowledge that the top bits are not
// demanded.
if (SimplifyDemandedBits(SDOperand(N, 0)))
return SDOperand(N, 0);
// fold (sext_in_reg (load x)) -> (smaller sextload x)
// fold (sext_in_reg (srl (load x), c)) -> (smaller sextload (x+c/evtbits))
SDOperand NarrowLoad = ReduceLoadWidth(N);
if (NarrowLoad.Val)
return NarrowLoad;
// fold (sext_in_reg (srl X, 24), i8) -> sra X, 24
// fold (sext_in_reg (srl X, 23), i8) -> sra X, 23 iff possible.
// We already fold "(sext_in_reg (srl X, 25), i8) -> srl X, 25" above.
if (N0.getOpcode() == ISD::SRL) {
if (ConstantSDNode *ShAmt = dyn_cast<ConstantSDNode>(N0.getOperand(1)))
if (ShAmt->getValue()+EVTBits <= VT.getSizeInBits()) {
// We can turn this into an SRA iff the input to the SRL is already sign
// extended enough.
unsigned InSignBits = DAG.ComputeNumSignBits(N0.getOperand(0));
if (VT.getSizeInBits()-(ShAmt->getValue()+EVTBits) < InSignBits)
return DAG.getNode(ISD::SRA, VT, N0.getOperand(0), N0.getOperand(1));
}
}
// fold (sext_inreg (extload x)) -> (sextload x)
if (ISD::isEXTLoad(N0.Val) &&
ISD::isUNINDEXEDLoad(N0.Val) &&
EVT == cast<LoadSDNode>(N0)->getMemoryVT() &&
((!AfterLegalize && !cast<LoadSDNode>(N0)->isVolatile()) ||
TLI.isLoadXLegal(ISD::SEXTLOAD, EVT))) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
SDOperand ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, VT, LN0->getChain(),
LN0->getBasePtr(), LN0->getSrcValue(),
LN0->getSrcValueOffset(), EVT,
LN0->isVolatile(),
LN0->getAlignment());
CombineTo(N, ExtLoad);
CombineTo(N0.Val, ExtLoad, ExtLoad.getValue(1));
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
// fold (sext_inreg (zextload x)) -> (sextload x) iff load has one use
if (ISD::isZEXTLoad(N0.Val) && ISD::isUNINDEXEDLoad(N0.Val) &&
N0.hasOneUse() &&
EVT == cast<LoadSDNode>(N0)->getMemoryVT() &&
((!AfterLegalize && !cast<LoadSDNode>(N0)->isVolatile()) ||
TLI.isLoadXLegal(ISD::SEXTLOAD, EVT))) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
SDOperand ExtLoad = DAG.getExtLoad(ISD::SEXTLOAD, VT, LN0->getChain(),
LN0->getBasePtr(), LN0->getSrcValue(),
LN0->getSrcValueOffset(), EVT,
LN0->isVolatile(),
LN0->getAlignment());
CombineTo(N, ExtLoad);
CombineTo(N0.Val, ExtLoad, ExtLoad.getValue(1));
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
return SDOperand();
}
SDOperand DAGCombiner::visitTRUNCATE(SDNode *N) {
SDOperand N0 = N->getOperand(0);
MVT VT = N->getValueType(0);
// noop truncate
if (N0.getValueType() == N->getValueType(0))
return N0;
// fold (truncate c1) -> c1
if (isa<ConstantSDNode>(N0))
return DAG.getNode(ISD::TRUNCATE, VT, N0);
// fold (truncate (truncate x)) -> (truncate x)
if (N0.getOpcode() == ISD::TRUNCATE)
return DAG.getNode(ISD::TRUNCATE, VT, N0.getOperand(0));
// fold (truncate (ext x)) -> (ext x) or (truncate x) or x
if (N0.getOpcode() == ISD::ZERO_EXTEND || N0.getOpcode() == ISD::SIGN_EXTEND||
N0.getOpcode() == ISD::ANY_EXTEND) {
if (N0.getOperand(0).getValueType().bitsLT(VT))
// if the source is smaller than the dest, we still need an extend
return DAG.getNode(N0.getOpcode(), VT, N0.getOperand(0));
else if (N0.getOperand(0).getValueType().bitsGT(VT))
// if the source is larger than the dest, than we just need the truncate
return DAG.getNode(ISD::TRUNCATE, VT, N0.getOperand(0));
else
// if the source and dest are the same type, we can drop both the extend
// and the truncate
return N0.getOperand(0);
}
// See if we can simplify the input to this truncate through knowledge that
// only the low bits are being used. For example "trunc (or (shl x, 8), y)"
// -> trunc y
SDOperand Shorter =
GetDemandedBits(N0, APInt::getLowBitsSet(N0.getValueSizeInBits(),
VT.getSizeInBits()));
if (Shorter.Val)
return DAG.getNode(ISD::TRUNCATE, VT, Shorter);
// fold (truncate (load x)) -> (smaller load x)
// fold (truncate (srl (load x), c)) -> (smaller load (x+c/evtbits))
return ReduceLoadWidth(N);
}
static SDNode *getBuildPairElt(SDNode *N, unsigned i) {
SDOperand Elt = N->getOperand(i);
if (Elt.getOpcode() != ISD::MERGE_VALUES)
return Elt.Val;
return Elt.getOperand(Elt.ResNo).Val;
}
/// CombineConsecutiveLoads - build_pair (load, load) -> load
/// if load locations are consecutive.
SDOperand DAGCombiner::CombineConsecutiveLoads(SDNode *N, MVT VT) {
assert(N->getOpcode() == ISD::BUILD_PAIR);
SDNode *LD1 = getBuildPairElt(N, 0);
if (!ISD::isNON_EXTLoad(LD1) || !LD1->hasOneUse())
return SDOperand();
MVT LD1VT = LD1->getValueType(0);
SDNode *LD2 = getBuildPairElt(N, 1);
const MachineFrameInfo *MFI = DAG.getMachineFunction().getFrameInfo();
if (ISD::isNON_EXTLoad(LD2) &&
LD2->hasOneUse() &&
// If both are volatile this would reduce the number of volatile loads.
// If one is volatile it might be ok, but play conservative and bail out.
!cast<LoadSDNode>(LD1)->isVolatile() &&
!cast<LoadSDNode>(LD2)->isVolatile() &&
TLI.isConsecutiveLoad(LD2, LD1, LD1VT.getSizeInBits()/8, 1, MFI)) {
LoadSDNode *LD = cast<LoadSDNode>(LD1);
unsigned Align = LD->getAlignment();
unsigned NewAlign = TLI.getTargetMachine().getTargetData()->
getABITypeAlignment(VT.getTypeForMVT());
if (NewAlign <= Align &&
(!AfterLegalize || TLI.isOperationLegal(ISD::LOAD, VT)))
return DAG.getLoad(VT, LD->getChain(), LD->getBasePtr(),
LD->getSrcValue(), LD->getSrcValueOffset(),
false, Align);
}
return SDOperand();
}
SDOperand DAGCombiner::visitBIT_CONVERT(SDNode *N) {
SDOperand N0 = N->getOperand(0);
MVT VT = N->getValueType(0);
// If the input is a BUILD_VECTOR with all constant elements, fold this now.
// Only do this before legalize, since afterward the target may be depending
// on the bitconvert.
// First check to see if this is all constant.
if (!AfterLegalize &&
N0.getOpcode() == ISD::BUILD_VECTOR && N0.Val->hasOneUse() &&
VT.isVector()) {
bool isSimple = true;
for (unsigned i = 0, e = N0.getNumOperands(); i != e; ++i)
if (N0.getOperand(i).getOpcode() != ISD::UNDEF &&
N0.getOperand(i).getOpcode() != ISD::Constant &&
N0.getOperand(i).getOpcode() != ISD::ConstantFP) {
isSimple = false;
break;
}
MVT DestEltVT = N->getValueType(0).getVectorElementType();
assert(!DestEltVT.isVector() &&
"Element type of vector ValueType must not be vector!");
if (isSimple) {
return ConstantFoldBIT_CONVERTofBUILD_VECTOR(N0.Val, DestEltVT);
}
}
// If the input is a constant, let getNode() fold it.
if (isa<ConstantSDNode>(N0) || isa<ConstantFPSDNode>(N0)) {
SDOperand Res = DAG.getNode(ISD::BIT_CONVERT, VT, N0);
if (Res.Val != N) return Res;
}
if (N0.getOpcode() == ISD::BIT_CONVERT) // conv(conv(x,t1),t2) -> conv(x,t2)
return DAG.getNode(ISD::BIT_CONVERT, VT, N0.getOperand(0));
// fold (conv (load x)) -> (load (conv*)x)
// If the resultant load doesn't need a higher alignment than the original!
if (ISD::isNormalLoad(N0.Val) && N0.hasOneUse() &&
// Do not change the width of a volatile load.
!cast<LoadSDNode>(N0)->isVolatile() &&
(!AfterLegalize || TLI.isOperationLegal(ISD::LOAD, VT))) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
unsigned Align = TLI.getTargetMachine().getTargetData()->
getABITypeAlignment(VT.getTypeForMVT());
unsigned OrigAlign = LN0->getAlignment();
if (Align <= OrigAlign) {
SDOperand Load = DAG.getLoad(VT, LN0->getChain(), LN0->getBasePtr(),
LN0->getSrcValue(), LN0->getSrcValueOffset(),
LN0->isVolatile(), Align);
AddToWorkList(N);
CombineTo(N0.Val, DAG.getNode(ISD::BIT_CONVERT, N0.getValueType(), Load),
Load.getValue(1));
return Load;
}
}
// Fold bitconvert(fneg(x)) -> xor(bitconvert(x), signbit)
// Fold bitconvert(fabs(x)) -> and(bitconvert(x), ~signbit)
// This often reduces constant pool loads.
if ((N0.getOpcode() == ISD::FNEG || N0.getOpcode() == ISD::FABS) &&
N0.Val->hasOneUse() && VT.isInteger() && !VT.isVector()) {
SDOperand NewConv = DAG.getNode(ISD::BIT_CONVERT, VT, N0.getOperand(0));
AddToWorkList(NewConv.Val);
APInt SignBit = APInt::getSignBit(VT.getSizeInBits());
if (N0.getOpcode() == ISD::FNEG)
return DAG.getNode(ISD::XOR, VT, NewConv, DAG.getConstant(SignBit, VT));
assert(N0.getOpcode() == ISD::FABS);
return DAG.getNode(ISD::AND, VT, NewConv, DAG.getConstant(~SignBit, VT));
}
// Fold bitconvert(fcopysign(cst, x)) -> bitconvert(x)&sign | cst&~sign'
// Note that we don't handle copysign(x,cst) because this can always be folded
// to an fneg or fabs.
if (N0.getOpcode() == ISD::FCOPYSIGN && N0.Val->hasOneUse() &&
isa<ConstantFPSDNode>(N0.getOperand(0)) &&
VT.isInteger() && !VT.isVector()) {
unsigned OrigXWidth = N0.getOperand(1).getValueType().getSizeInBits();
SDOperand X = DAG.getNode(ISD::BIT_CONVERT,
MVT::getIntegerVT(OrigXWidth),
N0.getOperand(1));
AddToWorkList(X.Val);
// If X has a different width than the result/lhs, sext it or truncate it.
unsigned VTWidth = VT.getSizeInBits();
if (OrigXWidth < VTWidth) {
X = DAG.getNode(ISD::SIGN_EXTEND, VT, X);
AddToWorkList(X.Val);
} else if (OrigXWidth > VTWidth) {
// To get the sign bit in the right place, we have to shift it right
// before truncating.
X = DAG.getNode(ISD::SRL, X.getValueType(), X,
DAG.getConstant(OrigXWidth-VTWidth, X.getValueType()));
AddToWorkList(X.Val);
X = DAG.getNode(ISD::TRUNCATE, VT, X);
AddToWorkList(X.Val);
}
APInt SignBit = APInt::getSignBit(VT.getSizeInBits());
X = DAG.getNode(ISD::AND, VT, X, DAG.getConstant(SignBit, VT));
AddToWorkList(X.Val);
SDOperand Cst = DAG.getNode(ISD::BIT_CONVERT, VT, N0.getOperand(0));
Cst = DAG.getNode(ISD::AND, VT, Cst, DAG.getConstant(~SignBit, VT));
AddToWorkList(Cst.Val);
return DAG.getNode(ISD::OR, VT, X, Cst);
}
// bitconvert(build_pair(ld, ld)) -> ld iff load locations are consecutive.
if (N0.getOpcode() == ISD::BUILD_PAIR) {
SDOperand CombineLD = CombineConsecutiveLoads(N0.Val, VT);
if (CombineLD.Val)
return CombineLD;
}
return SDOperand();
}
SDOperand DAGCombiner::visitBUILD_PAIR(SDNode *N) {
MVT VT = N->getValueType(0);
return CombineConsecutiveLoads(N, VT);
}
/// ConstantFoldBIT_CONVERTofBUILD_VECTOR - We know that BV is a build_vector
/// node with Constant, ConstantFP or Undef operands. DstEltVT indicates the
/// destination element value type.
SDOperand DAGCombiner::
ConstantFoldBIT_CONVERTofBUILD_VECTOR(SDNode *BV, MVT DstEltVT) {
MVT SrcEltVT = BV->getOperand(0).getValueType();
// If this is already the right type, we're done.
if (SrcEltVT == DstEltVT) return SDOperand(BV, 0);
unsigned SrcBitSize = SrcEltVT.getSizeInBits();
unsigned DstBitSize = DstEltVT.getSizeInBits();
// If this is a conversion of N elements of one type to N elements of another
// type, convert each element. This handles FP<->INT cases.
if (SrcBitSize == DstBitSize) {
SmallVector<SDOperand, 8> Ops;
for (unsigned i = 0, e = BV->getNumOperands(); i != e; ++i) {
Ops.push_back(DAG.getNode(ISD::BIT_CONVERT, DstEltVT, BV->getOperand(i)));
AddToWorkList(Ops.back().Val);
}
MVT VT = MVT::getVectorVT(DstEltVT,
BV->getValueType(0).getVectorNumElements());
return DAG.getNode(ISD::BUILD_VECTOR, VT, &Ops[0], Ops.size());
}
// Otherwise, we're growing or shrinking the elements. To avoid having to
// handle annoying details of growing/shrinking FP values, we convert them to
// int first.
if (SrcEltVT.isFloatingPoint()) {
// Convert the input float vector to a int vector where the elements are the
// same sizes.
assert((SrcEltVT == MVT::f32 || SrcEltVT == MVT::f64) && "Unknown FP VT!");
MVT IntVT = MVT::getIntegerVT(SrcEltVT.getSizeInBits());
BV = ConstantFoldBIT_CONVERTofBUILD_VECTOR(BV, IntVT).Val;
SrcEltVT = IntVT;
}
// Now we know the input is an integer vector. If the output is a FP type,
// convert to integer first, then to FP of the right size.
if (DstEltVT.isFloatingPoint()) {
assert((DstEltVT == MVT::f32 || DstEltVT == MVT::f64) && "Unknown FP VT!");
MVT TmpVT = MVT::getIntegerVT(DstEltVT.getSizeInBits());
SDNode *Tmp = ConstantFoldBIT_CONVERTofBUILD_VECTOR(BV, TmpVT).Val;
// Next, convert to FP elements of the same size.
return ConstantFoldBIT_CONVERTofBUILD_VECTOR(Tmp, DstEltVT);
}
// Okay, we know the src/dst types are both integers of differing types.
// Handling growing first.
assert(SrcEltVT.isInteger() && DstEltVT.isInteger());
if (SrcBitSize < DstBitSize) {
unsigned NumInputsPerOutput = DstBitSize/SrcBitSize;
SmallVector<SDOperand, 8> Ops;
for (unsigned i = 0, e = BV->getNumOperands(); i != e;
i += NumInputsPerOutput) {
bool isLE = TLI.isLittleEndian();
APInt NewBits = APInt(DstBitSize, 0);
bool EltIsUndef = true;
for (unsigned j = 0; j != NumInputsPerOutput; ++j) {
// Shift the previously computed bits over.
NewBits <<= SrcBitSize;
SDOperand Op = BV->getOperand(i+ (isLE ? (NumInputsPerOutput-j-1) : j));
if (Op.getOpcode() == ISD::UNDEF) continue;
EltIsUndef = false;
NewBits |=
APInt(cast<ConstantSDNode>(Op)->getAPIntValue()).zext(DstBitSize);
}
if (EltIsUndef)
Ops.push_back(DAG.getNode(ISD::UNDEF, DstEltVT));
else
Ops.push_back(DAG.getConstant(NewBits, DstEltVT));
}
MVT VT = MVT::getVectorVT(DstEltVT, Ops.size());
return DAG.getNode(ISD::BUILD_VECTOR, VT, &Ops[0], Ops.size());
}
// Finally, this must be the case where we are shrinking elements: each input
// turns into multiple outputs.
bool isS2V = ISD::isScalarToVector(BV);
unsigned NumOutputsPerInput = SrcBitSize/DstBitSize;
MVT VT = MVT::getVectorVT(DstEltVT, NumOutputsPerInput*BV->getNumOperands());
SmallVector<SDOperand, 8> Ops;
for (unsigned i = 0, e = BV->getNumOperands(); i != e; ++i) {
if (BV->getOperand(i).getOpcode() == ISD::UNDEF) {
for (unsigned j = 0; j != NumOutputsPerInput; ++j)
Ops.push_back(DAG.getNode(ISD::UNDEF, DstEltVT));
continue;
}
APInt OpVal = cast<ConstantSDNode>(BV->getOperand(i))->getAPIntValue();
for (unsigned j = 0; j != NumOutputsPerInput; ++j) {
APInt ThisVal = APInt(OpVal).trunc(DstBitSize);
Ops.push_back(DAG.getConstant(ThisVal, DstEltVT));
if (isS2V && i == 0 && j == 0 && APInt(ThisVal).zext(SrcBitSize) == OpVal)
// Simply turn this into a SCALAR_TO_VECTOR of the new type.
return DAG.getNode(ISD::SCALAR_TO_VECTOR, VT, Ops[0]);
OpVal = OpVal.lshr(DstBitSize);
}
// For big endian targets, swap the order of the pieces of each element.
if (TLI.isBigEndian())
std::reverse(Ops.end()-NumOutputsPerInput, Ops.end());
}
return DAG.getNode(ISD::BUILD_VECTOR, VT, &Ops[0], Ops.size());
}
SDOperand DAGCombiner::visitFADD(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1);
MVT VT = N->getValueType(0);
// fold vector ops
if (VT.isVector()) {
SDOperand FoldedVOp = SimplifyVBinOp(N);
if (FoldedVOp.Val) return FoldedVOp;
}
// fold (fadd c1, c2) -> c1+c2
if (N0CFP && N1CFP && VT != MVT::ppcf128)
return DAG.getNode(ISD::FADD, VT, N0, N1);
// canonicalize constant to RHS
if (N0CFP && !N1CFP)
return DAG.getNode(ISD::FADD, VT, N1, N0);
// fold (A + (-B)) -> A-B
if (isNegatibleForFree(N1, AfterLegalize) == 2)
return DAG.getNode(ISD::FSUB, VT, N0,
GetNegatedExpression(N1, DAG, AfterLegalize));
// fold ((-A) + B) -> B-A
if (isNegatibleForFree(N0, AfterLegalize) == 2)
return DAG.getNode(ISD::FSUB, VT, N1,
GetNegatedExpression(N0, DAG, AfterLegalize));
// If allowed, fold (fadd (fadd x, c1), c2) -> (fadd x, (fadd c1, c2))
if (UnsafeFPMath && N1CFP && N0.getOpcode() == ISD::FADD &&
N0.Val->hasOneUse() && isa<ConstantFPSDNode>(N0.getOperand(1)))
return DAG.getNode(ISD::FADD, VT, N0.getOperand(0),
DAG.getNode(ISD::FADD, VT, N0.getOperand(1), N1));
return SDOperand();
}
SDOperand DAGCombiner::visitFSUB(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1);
MVT VT = N->getValueType(0);
// fold vector ops
if (VT.isVector()) {
SDOperand FoldedVOp = SimplifyVBinOp(N);
if (FoldedVOp.Val) return FoldedVOp;
}
// fold (fsub c1, c2) -> c1-c2
if (N0CFP && N1CFP && VT != MVT::ppcf128)
return DAG.getNode(ISD::FSUB, VT, N0, N1);
// fold (0-B) -> -B
if (UnsafeFPMath && N0CFP && N0CFP->getValueAPF().isZero()) {
if (isNegatibleForFree(N1, AfterLegalize))
return GetNegatedExpression(N1, DAG, AfterLegalize);
return DAG.getNode(ISD::FNEG, VT, N1);
}
// fold (A-(-B)) -> A+B
if (isNegatibleForFree(N1, AfterLegalize))
return DAG.getNode(ISD::FADD, VT, N0,
GetNegatedExpression(N1, DAG, AfterLegalize));
return SDOperand();
}
SDOperand DAGCombiner::visitFMUL(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1);
MVT VT = N->getValueType(0);
// fold vector ops
if (VT.isVector()) {
SDOperand FoldedVOp = SimplifyVBinOp(N);
if (FoldedVOp.Val) return FoldedVOp;
}
// fold (fmul c1, c2) -> c1*c2
if (N0CFP && N1CFP && VT != MVT::ppcf128)
return DAG.getNode(ISD::FMUL, VT, N0, N1);
// canonicalize constant to RHS
if (N0CFP && !N1CFP)
return DAG.getNode(ISD::FMUL, VT, N1, N0);
// fold (fmul X, 2.0) -> (fadd X, X)
if (N1CFP && N1CFP->isExactlyValue(+2.0))
return DAG.getNode(ISD::FADD, VT, N0, N0);
// fold (fmul X, -1.0) -> (fneg X)
if (N1CFP && N1CFP->isExactlyValue(-1.0))
return DAG.getNode(ISD::FNEG, VT, N0);
// -X * -Y -> X*Y
if (char LHSNeg = isNegatibleForFree(N0, AfterLegalize)) {
if (char RHSNeg = isNegatibleForFree(N1, AfterLegalize)) {
// Both can be negated for free, check to see if at least one is cheaper
// negated.
if (LHSNeg == 2 || RHSNeg == 2)
return DAG.getNode(ISD::FMUL, VT,
GetNegatedExpression(N0, DAG, AfterLegalize),
GetNegatedExpression(N1, DAG, AfterLegalize));
}
}
// If allowed, fold (fmul (fmul x, c1), c2) -> (fmul x, (fmul c1, c2))
if (UnsafeFPMath && N1CFP && N0.getOpcode() == ISD::FMUL &&
N0.Val->hasOneUse() && isa<ConstantFPSDNode>(N0.getOperand(1)))
return DAG.getNode(ISD::FMUL, VT, N0.getOperand(0),
DAG.getNode(ISD::FMUL, VT, N0.getOperand(1), N1));
return SDOperand();
}
SDOperand DAGCombiner::visitFDIV(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1);
MVT VT = N->getValueType(0);
// fold vector ops
if (VT.isVector()) {
SDOperand FoldedVOp = SimplifyVBinOp(N);
if (FoldedVOp.Val) return FoldedVOp;
}
// fold (fdiv c1, c2) -> c1/c2
if (N0CFP && N1CFP && VT != MVT::ppcf128)
return DAG.getNode(ISD::FDIV, VT, N0, N1);
// -X / -Y -> X*Y
if (char LHSNeg = isNegatibleForFree(N0, AfterLegalize)) {
if (char RHSNeg = isNegatibleForFree(N1, AfterLegalize)) {
// Both can be negated for free, check to see if at least one is cheaper
// negated.
if (LHSNeg == 2 || RHSNeg == 2)
return DAG.getNode(ISD::FDIV, VT,
GetNegatedExpression(N0, DAG, AfterLegalize),
GetNegatedExpression(N1, DAG, AfterLegalize));
}
}
return SDOperand();
}
SDOperand DAGCombiner::visitFREM(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1);
MVT VT = N->getValueType(0);
// fold (frem c1, c2) -> fmod(c1,c2)
if (N0CFP && N1CFP && VT != MVT::ppcf128)
return DAG.getNode(ISD::FREM, VT, N0, N1);
return SDOperand();
}
SDOperand DAGCombiner::visitFCOPYSIGN(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
ConstantFPSDNode *N1CFP = dyn_cast<ConstantFPSDNode>(N1);
MVT VT = N->getValueType(0);
if (N0CFP && N1CFP && VT != MVT::ppcf128) // Constant fold
return DAG.getNode(ISD::FCOPYSIGN, VT, N0, N1);
if (N1CFP) {
const APFloat& V = N1CFP->getValueAPF();
// copysign(x, c1) -> fabs(x) iff ispos(c1)
// copysign(x, c1) -> fneg(fabs(x)) iff isneg(c1)
if (!V.isNegative())
return DAG.getNode(ISD::FABS, VT, N0);
else
return DAG.getNode(ISD::FNEG, VT, DAG.getNode(ISD::FABS, VT, N0));
}
// copysign(fabs(x), y) -> copysign(x, y)
// copysign(fneg(x), y) -> copysign(x, y)
// copysign(copysign(x,z), y) -> copysign(x, y)
if (N0.getOpcode() == ISD::FABS || N0.getOpcode() == ISD::FNEG ||
N0.getOpcode() == ISD::FCOPYSIGN)
return DAG.getNode(ISD::FCOPYSIGN, VT, N0.getOperand(0), N1);
// copysign(x, abs(y)) -> abs(x)
if (N1.getOpcode() == ISD::FABS)
return DAG.getNode(ISD::FABS, VT, N0);
// copysign(x, copysign(y,z)) -> copysign(x, z)
if (N1.getOpcode() == ISD::FCOPYSIGN)
return DAG.getNode(ISD::FCOPYSIGN, VT, N0, N1.getOperand(1));
// copysign(x, fp_extend(y)) -> copysign(x, y)
// copysign(x, fp_round(y)) -> copysign(x, y)
if (N1.getOpcode() == ISD::FP_EXTEND || N1.getOpcode() == ISD::FP_ROUND)
return DAG.getNode(ISD::FCOPYSIGN, VT, N0, N1.getOperand(0));
return SDOperand();
}
SDOperand DAGCombiner::visitSINT_TO_FP(SDNode *N) {
SDOperand N0 = N->getOperand(0);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
MVT VT = N->getValueType(0);
// fold (sint_to_fp c1) -> c1fp
if (N0C && N0.getValueType() != MVT::ppcf128)
return DAG.getNode(ISD::SINT_TO_FP, VT, N0);
return SDOperand();
}
SDOperand DAGCombiner::visitUINT_TO_FP(SDNode *N) {
SDOperand N0 = N->getOperand(0);
ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0);
MVT VT = N->getValueType(0);
// fold (uint_to_fp c1) -> c1fp
if (N0C && N0.getValueType() != MVT::ppcf128)
return DAG.getNode(ISD::UINT_TO_FP, VT, N0);
return SDOperand();
}
SDOperand DAGCombiner::visitFP_TO_SINT(SDNode *N) {
SDOperand N0 = N->getOperand(0);
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
MVT VT = N->getValueType(0);
// fold (fp_to_sint c1fp) -> c1
if (N0CFP)
return DAG.getNode(ISD::FP_TO_SINT, VT, N0);
return SDOperand();
}
SDOperand DAGCombiner::visitFP_TO_UINT(SDNode *N) {
SDOperand N0 = N->getOperand(0);
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
MVT VT = N->getValueType(0);
// fold (fp_to_uint c1fp) -> c1
if (N0CFP && VT != MVT::ppcf128)
return DAG.getNode(ISD::FP_TO_UINT, VT, N0);
return SDOperand();
}
SDOperand DAGCombiner::visitFP_ROUND(SDNode *N) {
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
MVT VT = N->getValueType(0);
// fold (fp_round c1fp) -> c1fp
if (N0CFP && N0.getValueType() != MVT::ppcf128)
return DAG.getNode(ISD::FP_ROUND, VT, N0, N1);
// fold (fp_round (fp_extend x)) -> x
if (N0.getOpcode() == ISD::FP_EXTEND && VT == N0.getOperand(0).getValueType())
return N0.getOperand(0);
// fold (fp_round (fp_round x)) -> (fp_round x)
if (N0.getOpcode() == ISD::FP_ROUND) {
// This is a value preserving truncation if both round's are.
bool IsTrunc = N->getConstantOperandVal(1) == 1 &&
N0.Val->getConstantOperandVal(1) == 1;
return DAG.getNode(ISD::FP_ROUND, VT, N0.getOperand(0),
DAG.getIntPtrConstant(IsTrunc));
}
// fold (fp_round (copysign X, Y)) -> (copysign (fp_round X), Y)
if (N0.getOpcode() == ISD::FCOPYSIGN && N0.Val->hasOneUse()) {
SDOperand Tmp = DAG.getNode(ISD::FP_ROUND, VT, N0.getOperand(0), N1);
AddToWorkList(Tmp.Val);
return DAG.getNode(ISD::FCOPYSIGN, VT, Tmp, N0.getOperand(1));
}
return SDOperand();
}
SDOperand DAGCombiner::visitFP_ROUND_INREG(SDNode *N) {
SDOperand N0 = N->getOperand(0);
MVT VT = N->getValueType(0);
MVT EVT = cast<VTSDNode>(N->getOperand(1))->getVT();
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
// fold (fp_round_inreg c1fp) -> c1fp
if (N0CFP) {
SDOperand Round = DAG.getConstantFP(N0CFP->getValueAPF(), EVT);
return DAG.getNode(ISD::FP_EXTEND, VT, Round);
}
return SDOperand();
}
SDOperand DAGCombiner::visitFP_EXTEND(SDNode *N) {
SDOperand N0 = N->getOperand(0);
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
MVT VT = N->getValueType(0);
// If this is fp_round(fpextend), don't fold it, allow ourselves to be folded.
if (N->hasOneUse() &&
N->use_begin()->getSDOperand().getOpcode() == ISD::FP_ROUND)
return SDOperand();
// fold (fp_extend c1fp) -> c1fp
if (N0CFP && VT != MVT::ppcf128)
return DAG.getNode(ISD::FP_EXTEND, VT, N0);
// Turn fp_extend(fp_round(X, 1)) -> x since the fp_round doesn't affect the
// value of X.
if (N0.getOpcode() == ISD::FP_ROUND && N0.Val->getConstantOperandVal(1) == 1){
SDOperand In = N0.getOperand(0);
if (In.getValueType() == VT) return In;
if (VT.bitsLT(In.getValueType()))
return DAG.getNode(ISD::FP_ROUND, VT, In, N0.getOperand(1));
return DAG.getNode(ISD::FP_EXTEND, VT, In);
}
// fold (fpext (load x)) -> (fpext (fptrunc (extload x)))
if (ISD::isNON_EXTLoad(N0.Val) && N0.hasOneUse() &&
((!AfterLegalize && !cast<LoadSDNode>(N0)->isVolatile()) ||
TLI.isLoadXLegal(ISD::EXTLOAD, N0.getValueType()))) {
LoadSDNode *LN0 = cast<LoadSDNode>(N0);
SDOperand ExtLoad = DAG.getExtLoad(ISD::EXTLOAD, VT, LN0->getChain(),
LN0->getBasePtr(), LN0->getSrcValue(),
LN0->getSrcValueOffset(),
N0.getValueType(),
LN0->isVolatile(),
LN0->getAlignment());
CombineTo(N, ExtLoad);
CombineTo(N0.Val, DAG.getNode(ISD::FP_ROUND, N0.getValueType(), ExtLoad,
DAG.getIntPtrConstant(1)),
ExtLoad.getValue(1));
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
return SDOperand();
}
SDOperand DAGCombiner::visitFNEG(SDNode *N) {
SDOperand N0 = N->getOperand(0);
if (isNegatibleForFree(N0, AfterLegalize))
return GetNegatedExpression(N0, DAG, AfterLegalize);
// Transform fneg(bitconvert(x)) -> bitconvert(x^sign) to avoid loading
// constant pool values.
if (N0.getOpcode() == ISD::BIT_CONVERT && N0.Val->hasOneUse() &&
N0.getOperand(0).getValueType().isInteger() &&
!N0.getOperand(0).getValueType().isVector()) {
SDOperand Int = N0.getOperand(0);
MVT IntVT = Int.getValueType();
if (IntVT.isInteger() && !IntVT.isVector()) {
Int = DAG.getNode(ISD::XOR, IntVT, Int,
DAG.getConstant(IntVT.getIntegerVTSignBit(), IntVT));
AddToWorkList(Int.Val);
return DAG.getNode(ISD::BIT_CONVERT, N->getValueType(0), Int);
}
}
return SDOperand();
}
SDOperand DAGCombiner::visitFABS(SDNode *N) {
SDOperand N0 = N->getOperand(0);
ConstantFPSDNode *N0CFP = dyn_cast<ConstantFPSDNode>(N0);
MVT VT = N->getValueType(0);
// fold (fabs c1) -> fabs(c1)
if (N0CFP && VT != MVT::ppcf128)
return DAG.getNode(ISD::FABS, VT, N0);
// fold (fabs (fabs x)) -> (fabs x)
if (N0.getOpcode() == ISD::FABS)
return N->getOperand(0);
// fold (fabs (fneg x)) -> (fabs x)
// fold (fabs (fcopysign x, y)) -> (fabs x)
if (N0.getOpcode() == ISD::FNEG || N0.getOpcode() == ISD::FCOPYSIGN)
return DAG.getNode(ISD::FABS, VT, N0.getOperand(0));
// Transform fabs(bitconvert(x)) -> bitconvert(x&~sign) to avoid loading
// constant pool values.
if (N0.getOpcode() == ISD::BIT_CONVERT && N0.Val->hasOneUse() &&
N0.getOperand(0).getValueType().isInteger() &&
!N0.getOperand(0).getValueType().isVector()) {
SDOperand Int = N0.getOperand(0);
MVT IntVT = Int.getValueType();
if (IntVT.isInteger() && !IntVT.isVector()) {
Int = DAG.getNode(ISD::AND, IntVT, Int,
DAG.getConstant(~IntVT.getIntegerVTSignBit(), IntVT));
AddToWorkList(Int.Val);
return DAG.getNode(ISD::BIT_CONVERT, N->getValueType(0), Int);
}
}
return SDOperand();
}
SDOperand DAGCombiner::visitBRCOND(SDNode *N) {
SDOperand Chain = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
SDOperand N2 = N->getOperand(2);
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1);
// never taken branch, fold to chain
if (N1C && N1C->isNullValue())
return Chain;
// unconditional branch
if (N1C && N1C->getAPIntValue() == 1)
return DAG.getNode(ISD::BR, MVT::Other, Chain, N2);
// fold a brcond with a setcc condition into a BR_CC node if BR_CC is legal
// on the target.
if (N1.getOpcode() == ISD::SETCC &&
TLI.isOperationLegal(ISD::BR_CC, MVT::Other)) {
return DAG.getNode(ISD::BR_CC, MVT::Other, Chain, N1.getOperand(2),
N1.getOperand(0), N1.getOperand(1), N2);
}
return SDOperand();
}
// Operand List for BR_CC: Chain, CondCC, CondLHS, CondRHS, DestBB.
//
SDOperand DAGCombiner::visitBR_CC(SDNode *N) {
CondCodeSDNode *CC = cast<CondCodeSDNode>(N->getOperand(1));
SDOperand CondLHS = N->getOperand(2), CondRHS = N->getOperand(3);
// Use SimplifySetCC to simplify SETCC's.
SDOperand Simp = SimplifySetCC(MVT::i1, CondLHS, CondRHS, CC->get(), false);
if (Simp.Val) AddToWorkList(Simp.Val);
ConstantSDNode *SCCC = dyn_cast_or_null<ConstantSDNode>(Simp.Val);
// fold br_cc true, dest -> br dest (unconditional branch)
if (SCCC && !SCCC->isNullValue())
return DAG.getNode(ISD::BR, MVT::Other, N->getOperand(0),
N->getOperand(4));
// fold br_cc false, dest -> unconditional fall through
if (SCCC && SCCC->isNullValue())
return N->getOperand(0);
// fold to a simpler setcc
if (Simp.Val && Simp.getOpcode() == ISD::SETCC)
return DAG.getNode(ISD::BR_CC, MVT::Other, N->getOperand(0),
Simp.getOperand(2), Simp.getOperand(0),
Simp.getOperand(1), N->getOperand(4));
return SDOperand();
}
/// CombineToPreIndexedLoadStore - Try turning a load / store into a
/// pre-indexed load / store when the base pointer is an add or subtract
/// and it has other uses besides the load / store. After the
/// transformation, the new indexed load / store has effectively folded
/// the add / subtract in and all of its other uses are redirected to the
/// new load / store.
bool DAGCombiner::CombineToPreIndexedLoadStore(SDNode *N) {
if (!AfterLegalize)
return false;
bool isLoad = true;
SDOperand Ptr;
MVT VT;
if (LoadSDNode *LD = dyn_cast<LoadSDNode>(N)) {
if (LD->isIndexed())
return false;
VT = LD->getMemoryVT();
if (!TLI.isIndexedLoadLegal(ISD::PRE_INC, VT) &&
!TLI.isIndexedLoadLegal(ISD::PRE_DEC, VT))
return false;
Ptr = LD->getBasePtr();
} else if (StoreSDNode *ST = dyn_cast<StoreSDNode>(N)) {
if (ST->isIndexed())
return false;
VT = ST->getMemoryVT();
if (!TLI.isIndexedStoreLegal(ISD::PRE_INC, VT) &&
!TLI.isIndexedStoreLegal(ISD::PRE_DEC, VT))
return false;
Ptr = ST->getBasePtr();
isLoad = false;
} else
return false;
// If the pointer is not an add/sub, or if it doesn't have multiple uses, bail
// out. There is no reason to make this a preinc/predec.
if ((Ptr.getOpcode() != ISD::ADD && Ptr.getOpcode() != ISD::SUB) ||
Ptr.Val->hasOneUse())
return false;
// Ask the target to do addressing mode selection.
SDOperand BasePtr;
SDOperand Offset;
ISD::MemIndexedMode AM = ISD::UNINDEXED;
if (!TLI.getPreIndexedAddressParts(N, BasePtr, Offset, AM, DAG))
return false;
// Don't create a indexed load / store with zero offset.
if (isa<ConstantSDNode>(Offset) &&
cast<ConstantSDNode>(Offset)->isNullValue())
return false;
// Try turning it into a pre-indexed load / store except when:
// 1) The new base ptr is a frame index.
// 2) If N is a store and the new base ptr is either the same as or is a
// predecessor of the value being stored.
// 3) Another use of old base ptr is a predecessor of N. If ptr is folded
// that would create a cycle.
// 4) All uses are load / store ops that use it as old base ptr.
// Check #1. Preinc'ing a frame index would require copying the stack pointer
// (plus the implicit offset) to a register to preinc anyway.
if (isa<FrameIndexSDNode>(BasePtr))
return false;
// Check #2.
if (!isLoad) {
SDOperand Val = cast<StoreSDNode>(N)->getValue();
if (Val == BasePtr || BasePtr.Val->isPredecessorOf(Val.Val))
return false;
}
// Now check for #3 and #4.
bool RealUse = false;
for (SDNode::use_iterator I = Ptr.Val->use_begin(),
E = Ptr.Val->use_end(); I != E; ++I) {
SDNode *Use = I->getUser();
if (Use == N)
continue;
if (Use->isPredecessorOf(N))
return false;
if (!((Use->getOpcode() == ISD::LOAD &&
cast<LoadSDNode>(Use)->getBasePtr() == Ptr) ||
(Use->getOpcode() == ISD::STORE &&
cast<StoreSDNode>(Use)->getBasePtr() == Ptr)))
RealUse = true;
}
if (!RealUse)
return false;
SDOperand Result;
if (isLoad)
Result = DAG.getIndexedLoad(SDOperand(N,0), BasePtr, Offset, AM);
else
Result = DAG.getIndexedStore(SDOperand(N,0), BasePtr, Offset, AM);
++PreIndexedNodes;
++NodesCombined;
DOUT << "\nReplacing.4 "; DEBUG(N->dump(&DAG));
DOUT << "\nWith: "; DEBUG(Result.Val->dump(&DAG));
DOUT << '\n';
WorkListRemover DeadNodes(*this);
if (isLoad) {
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 0), Result.getValue(0),
&DeadNodes);
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 1), Result.getValue(2),
&DeadNodes);
} else {
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 0), Result.getValue(1),
&DeadNodes);
}
// Finally, since the node is now dead, remove it from the graph.
DAG.DeleteNode(N);
// Replace the uses of Ptr with uses of the updated base value.
DAG.ReplaceAllUsesOfValueWith(Ptr, Result.getValue(isLoad ? 1 : 0),
&DeadNodes);
removeFromWorkList(Ptr.Val);
DAG.DeleteNode(Ptr.Val);
return true;
}
/// CombineToPostIndexedLoadStore - Try to combine a load / store with a
/// add / sub of the base pointer node into a post-indexed load / store.
/// The transformation folded the add / subtract into the new indexed
/// load / store effectively and all of its uses are redirected to the
/// new load / store.
bool DAGCombiner::CombineToPostIndexedLoadStore(SDNode *N) {
if (!AfterLegalize)
return false;
bool isLoad = true;
SDOperand Ptr;
MVT VT;
if (LoadSDNode *LD = dyn_cast<LoadSDNode>(N)) {
if (LD->isIndexed())
return false;
VT = LD->getMemoryVT();
if (!TLI.isIndexedLoadLegal(ISD::POST_INC, VT) &&
!TLI.isIndexedLoadLegal(ISD::POST_DEC, VT))
return false;
Ptr = LD->getBasePtr();
} else if (StoreSDNode *ST = dyn_cast<StoreSDNode>(N)) {
if (ST->isIndexed())
return false;
VT = ST->getMemoryVT();
if (!TLI.isIndexedStoreLegal(ISD::POST_INC, VT) &&
!TLI.isIndexedStoreLegal(ISD::POST_DEC, VT))
return false;
Ptr = ST->getBasePtr();
isLoad = false;
} else
return false;
if (Ptr.Val->hasOneUse())
return false;
for (SDNode::use_iterator I = Ptr.Val->use_begin(),
E = Ptr.Val->use_end(); I != E; ++I) {
SDNode *Op = I->getUser();
if (Op == N ||
(Op->getOpcode() != ISD::ADD && Op->getOpcode() != ISD::SUB))
continue;
SDOperand BasePtr;
SDOperand Offset;
ISD::MemIndexedMode AM = ISD::UNINDEXED;
if (TLI.getPostIndexedAddressParts(N, Op, BasePtr, Offset, AM, DAG)) {
if (Ptr == Offset)
std::swap(BasePtr, Offset);
if (Ptr != BasePtr)
continue;
// Don't create a indexed load / store with zero offset.
if (isa<ConstantSDNode>(Offset) &&
cast<ConstantSDNode>(Offset)->isNullValue())
continue;
// Try turning it into a post-indexed load / store except when
// 1) All uses are load / store ops that use it as base ptr.
// 2) Op must be independent of N, i.e. Op is neither a predecessor
// nor a successor of N. Otherwise, if Op is folded that would
// create a cycle.
// Check for #1.
bool TryNext = false;
for (SDNode::use_iterator II = BasePtr.Val->use_begin(),
EE = BasePtr.Val->use_end(); II != EE; ++II) {
SDNode *Use = II->getUser();
if (Use == Ptr.Val)
continue;
// If all the uses are load / store addresses, then don't do the
// transformation.
if (Use->getOpcode() == ISD::ADD || Use->getOpcode() == ISD::SUB){
bool RealUse = false;
for (SDNode::use_iterator III = Use->use_begin(),
EEE = Use->use_end(); III != EEE; ++III) {
SDNode *UseUse = III->getUser();
if (!((UseUse->getOpcode() == ISD::LOAD &&
cast<LoadSDNode>(UseUse)->getBasePtr().Val == Use) ||
(UseUse->getOpcode() == ISD::STORE &&
cast<StoreSDNode>(UseUse)->getBasePtr().Val == Use)))
RealUse = true;
}
if (!RealUse) {
TryNext = true;
break;
}
}
}
if (TryNext)
continue;
// Check for #2
if (!Op->isPredecessorOf(N) && !N->isPredecessorOf(Op)) {
SDOperand Result = isLoad
? DAG.getIndexedLoad(SDOperand(N,0), BasePtr, Offset, AM)
: DAG.getIndexedStore(SDOperand(N,0), BasePtr, Offset, AM);
++PostIndexedNodes;
++NodesCombined;
DOUT << "\nReplacing.5 "; DEBUG(N->dump(&DAG));
DOUT << "\nWith: "; DEBUG(Result.Val->dump(&DAG));
DOUT << '\n';
WorkListRemover DeadNodes(*this);
if (isLoad) {
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 0), Result.getValue(0),
&DeadNodes);
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 1), Result.getValue(2),
&DeadNodes);
} else {
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 0), Result.getValue(1),
&DeadNodes);
}
// Finally, since the node is now dead, remove it from the graph.
DAG.DeleteNode(N);
// Replace the uses of Use with uses of the updated base value.
DAG.ReplaceAllUsesOfValueWith(SDOperand(Op, 0),
Result.getValue(isLoad ? 1 : 0),
&DeadNodes);
removeFromWorkList(Op);
DAG.DeleteNode(Op);
return true;
}
}
}
return false;
}
/// InferAlignment - If we can infer some alignment information from this
/// pointer, return it.
static unsigned InferAlignment(SDOperand Ptr, SelectionDAG &DAG) {
// If this is a direct reference to a stack slot, use information about the
// stack slot's alignment.
int FrameIdx = 1 << 31;
int64_t FrameOffset = 0;
if (FrameIndexSDNode *FI = dyn_cast<FrameIndexSDNode>(Ptr)) {
FrameIdx = FI->getIndex();
} else if (Ptr.getOpcode() == ISD::ADD &&
isa<ConstantSDNode>(Ptr.getOperand(1)) &&
isa<FrameIndexSDNode>(Ptr.getOperand(0))) {
FrameIdx = cast<FrameIndexSDNode>(Ptr.getOperand(0))->getIndex();
FrameOffset = Ptr.getConstantOperandVal(1);
}
if (FrameIdx != (1 << 31)) {
// FIXME: Handle FI+CST.
const MachineFrameInfo &MFI = *DAG.getMachineFunction().getFrameInfo();
if (MFI.isFixedObjectIndex(FrameIdx)) {
int64_t ObjectOffset = MFI.getObjectOffset(FrameIdx);
// The alignment of the frame index can be determined from its offset from
// the incoming frame position. If the frame object is at offset 32 and
// the stack is guaranteed to be 16-byte aligned, then we know that the
// object is 16-byte aligned.
unsigned StackAlign = DAG.getTarget().getFrameInfo()->getStackAlignment();
unsigned Align = MinAlign(ObjectOffset, StackAlign);
// Finally, the frame object itself may have a known alignment. Factor
// the alignment + offset into a new alignment. For example, if we know
// the FI is 8 byte aligned, but the pointer is 4 off, we really have a
// 4-byte alignment of the resultant pointer. Likewise align 4 + 4-byte
// offset = 4-byte alignment, align 4 + 1-byte offset = align 1, etc.
unsigned FIInfoAlign = MinAlign(MFI.getObjectAlignment(FrameIdx),
FrameOffset);
return std::max(Align, FIInfoAlign);
}
}
return 0;
}
SDOperand DAGCombiner::visitLOAD(SDNode *N) {
LoadSDNode *LD = cast<LoadSDNode>(N);
SDOperand Chain = LD->getChain();
SDOperand Ptr = LD->getBasePtr();
// Try to infer better alignment information than the load already has.
if (LD->isUnindexed()) {
if (unsigned Align = InferAlignment(Ptr, DAG)) {
if (Align > LD->getAlignment())
return DAG.getExtLoad(LD->getExtensionType(), LD->getValueType(0),
Chain, Ptr, LD->getSrcValue(),
LD->getSrcValueOffset(), LD->getMemoryVT(),
LD->isVolatile(), Align);
}
}
// If load is not volatile and there are no uses of the loaded value (and
// the updated indexed value in case of indexed loads), change uses of the
// chain value into uses of the chain input (i.e. delete the dead load).
if (!LD->isVolatile()) {
if (N->getValueType(1) == MVT::Other) {
// Unindexed loads.
if (N->hasNUsesOfValue(0, 0)) {
// It's not safe to use the two value CombineTo variant here. e.g.
// v1, chain2 = load chain1, loc
// v2, chain3 = load chain2, loc
// v3 = add v2, c
// Now we replace use of chain2 with chain1. This makes the second load
// isomorphic to the one we are deleting, and thus makes this load live.
DOUT << "\nReplacing.6 "; DEBUG(N->dump(&DAG));
DOUT << "\nWith chain: "; DEBUG(Chain.Val->dump(&DAG));
DOUT << "\n";
WorkListRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 1), Chain, &DeadNodes);
if (N->use_empty()) {
removeFromWorkList(N);
DAG.DeleteNode(N);
}
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
} else {
// Indexed loads.
assert(N->getValueType(2) == MVT::Other && "Malformed indexed loads?");
if (N->hasNUsesOfValue(0, 0) && N->hasNUsesOfValue(0, 1)) {
SDOperand Undef = DAG.getNode(ISD::UNDEF, N->getValueType(0));
DOUT << "\nReplacing.6 "; DEBUG(N->dump(&DAG));
DOUT << "\nWith: "; DEBUG(Undef.Val->dump(&DAG));
DOUT << " and 2 other values\n";
WorkListRemover DeadNodes(*this);
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 0), Undef, &DeadNodes);
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 1),
DAG.getNode(ISD::UNDEF, N->getValueType(1)),
&DeadNodes);
DAG.ReplaceAllUsesOfValueWith(SDOperand(N, 2), Chain, &DeadNodes);
removeFromWorkList(N);
DAG.DeleteNode(N);
return SDOperand(N, 0); // Return N so it doesn't get rechecked!
}
}
}
// If this load is directly stored, replace the load value with the stored
// value.
// TODO: Handle store large -> read small portion.
// TODO: Handle TRUNCSTORE/LOADEXT
if (LD->getExtensionType() == ISD::NON_EXTLOAD &&
!LD->isVolatile()) {
if (ISD::isNON_TRUNCStore(Chain.Val)) {
StoreSDNode *PrevST = cast<StoreSDNode>(Chain);
if (PrevST->getBasePtr() == Ptr &&
PrevST->getValue().getValueType() == N->getValueType(0))
return CombineTo(N, Chain.getOperand(1), Chain);
}
}
if (CombinerAA) {
// Walk up chain skipping non-aliasing memory nodes.
SDOperand BetterChain = FindBetterChain(N, Chain);
// If there is a better chain.
if (Chain != BetterChain) {
SDOperand ReplLoad;
// Replace the chain to void dependency.
if (LD->getExtensionType() == ISD::NON_EXTLOAD) {
ReplLoad = DAG.getLoad(N->getValueType(0), BetterChain, Ptr,
LD->getSrcValue(), LD->getSrcValueOffset(),
LD->isVolatile(), LD->getAlignment());
} else {
ReplLoad = DAG.getExtLoad(LD->getExtensionType(),
LD->getValueType(0),
BetterChain, Ptr, LD->getSrcValue(),
LD->getSrcValueOffset(),
LD->getMemoryVT(),
LD->isVolatile(),
LD->getAlignment());
}
// Create token factor to keep old chain connected.
SDOperand Token = DAG.getNode(ISD::TokenFactor, MVT::Other,
Chain, ReplLoad.getValue(1));
// Replace uses with load result and token factor. Don't add users
// to work list.
return CombineTo(N, ReplLoad.getValue(0), Token, false);
}
}
// Try transforming N to an indexed load.
if (CombineToPreIndexedLoadStore(N) || CombineToPostIndexedLoadStore(N))
return SDOperand(N, 0);
return SDOperand();
}
SDOperand DAGCombiner::visitSTORE(SDNode *N) {
StoreSDNode *ST = cast<StoreSDNode>(N);
SDOperand Chain = ST->getChain();
SDOperand Value = ST->getValue();
SDOperand Ptr = ST->getBasePtr();
// Try to infer better alignment information than the store already has.
if (ST->isUnindexed()) {
if (unsigned Align = InferAlignment(Ptr, DAG)) {
if (Align > ST->getAlignment())
return DAG.getTruncStore(Chain, Value, Ptr, ST->getSrcValue(),
ST->getSrcValueOffset(), ST->getMemoryVT(),
ST->isVolatile(), Align);
}
}
// If this is a store of a bit convert, store the input value if the
// resultant store does not need a higher alignment than the original.
if (Value.getOpcode() == ISD::BIT_CONVERT && !ST->isTruncatingStore() &&
ST->isUnindexed()) {
unsigned Align = ST->getAlignment();
MVT SVT = Value.getOperand(0).getValueType();
unsigned OrigAlign = TLI.getTargetMachine().getTargetData()->
getABITypeAlignment(SVT.getTypeForMVT());
if (Align <= OrigAlign &&
((!AfterLegalize && !ST->isVolatile()) ||
TLI.isOperationLegal(ISD::STORE, SVT)))
return DAG.getStore(Chain, Value.getOperand(0), Ptr, ST->getSrcValue(),
ST->getSrcValueOffset(), ST->isVolatile(), Align);
}
// Turn 'store float 1.0, Ptr' -> 'store int 0x12345678, Ptr'
if (ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(Value)) {
// NOTE: If the original store is volatile, this transform must not increase
// the number of stores. For example, on x86-32 an f64 can be stored in one
// processor operation but an i64 (which is not legal) requires two. So the
// transform should not be done in this case.
if (Value.getOpcode() != ISD::TargetConstantFP) {
SDOperand Tmp;
switch (CFP->getValueType(0).getSimpleVT()) {
default: assert(0 && "Unknown FP type");
case MVT::f80: // We don't do this for these yet.
case MVT::f128:
case MVT::ppcf128:
break;
case MVT::f32:
if ((!AfterLegalize && !ST->isVolatile()) ||
TLI.isOperationLegal(ISD::STORE, MVT::i32)) {
Tmp = DAG.getConstant((uint32_t)CFP->getValueAPF().
convertToAPInt().getZExtValue(), MVT::i32);
return DAG.getStore(Chain, Tmp, Ptr, ST->getSrcValue(),
ST->getSrcValueOffset(), ST->isVolatile(),
ST->getAlignment());
}
break;
case MVT::f64:
if ((!AfterLegalize && !ST->isVolatile()) ||
TLI.isOperationLegal(ISD::STORE, MVT::i64)) {
Tmp = DAG.getConstant(CFP->getValueAPF().convertToAPInt().
getZExtValue(), MVT::i64);
return DAG.getStore(Chain, Tmp, Ptr, ST->getSrcValue(),
ST->getSrcValueOffset(), ST->isVolatile(),
ST->getAlignment());
} else if (!ST->isVolatile() &&
TLI.isOperationLegal(ISD::STORE, MVT::i32)) {
// Many FP stores are not made apparent until after legalize, e.g. for
// argument passing. Since this is so common, custom legalize the
// 64-bit integer store into two 32-bit stores.
uint64_t Val = CFP->getValueAPF().convertToAPInt().getZExtValue();
SDOperand Lo = DAG.getConstant(Val & 0xFFFFFFFF, MVT::i32);
SDOperand Hi = DAG.getConstant(Val >> 32, MVT::i32);
if (TLI.isBigEndian()) std::swap(Lo, Hi);
int SVOffset = ST->getSrcValueOffset();
unsigned Alignment = ST->getAlignment();
bool isVolatile = ST->isVolatile();
SDOperand St0 = DAG.getStore(Chain, Lo, Ptr, ST->getSrcValue(),
ST->getSrcValueOffset(),
isVolatile, ST->getAlignment());
Ptr = DAG.getNode(ISD::ADD, Ptr.getValueType(), Ptr,
DAG.getConstant(4, Ptr.getValueType()));
SVOffset += 4;
Alignment = MinAlign(Alignment, 4U);
SDOperand St1 = DAG.getStore(Chain, Hi, Ptr, ST->getSrcValue(),
SVOffset, isVolatile, Alignment);
return DAG.getNode(ISD::TokenFactor, MVT::Other, St0, St1);
}
break;
}
}
}
if (CombinerAA) {
// Walk up chain skipping non-aliasing memory nodes.
SDOperand BetterChain = FindBetterChain(N, Chain);
// If there is a better chain.
if (Chain != BetterChain) {
// Replace the chain to avoid dependency.
SDOperand ReplStore;
if (ST->isTruncatingStore()) {
ReplStore = DAG.getTruncStore(BetterChain, Value, Ptr,
ST->getSrcValue(),ST->getSrcValueOffset(),
ST->getMemoryVT(),
ST->isVolatile(), ST->getAlignment());
} else {
ReplStore = DAG.getStore(BetterChain, Value, Ptr,
ST->getSrcValue(), ST->getSrcValueOffset(),
ST->isVolatile(), ST->getAlignment());
}
// Create token to keep both nodes around.
SDOperand Token =
DAG.getNode(ISD::TokenFactor, MVT::Other, Chain, ReplStore);
// Don't add users to work list.
return CombineTo(N, Token, false);
}
}
// Try transforming N to an indexed store.
if (CombineToPreIndexedLoadStore(N) || CombineToPostIndexedLoadStore(N))
return SDOperand(N, 0);
// FIXME: is there such a thing as a truncating indexed store?
if (ST->isTruncatingStore() && ST->isUnindexed() &&
Value.getValueType().isInteger()) {
// See if we can simplify the input to this truncstore with knowledge that
// only the low bits are being used. For example:
// "truncstore (or (shl x, 8), y), i8" -> "truncstore y, i8"
SDOperand Shorter =
GetDemandedBits(Value,
APInt::getLowBitsSet(Value.getValueSizeInBits(),
ST->getMemoryVT().getSizeInBits()));
AddToWorkList(Value.Val);
if (Shorter.Val)
return DAG.getTruncStore(Chain, Shorter, Ptr, ST->getSrcValue(),
ST->getSrcValueOffset(), ST->getMemoryVT(),
ST->isVolatile(), ST->getAlignment());
// Otherwise, see if we can simplify the operation with
// SimplifyDemandedBits, which only works if the value has a single use.
if (SimplifyDemandedBits(Value,
APInt::getLowBitsSet(
Value.getValueSizeInBits(),
ST->getMemoryVT().getSizeInBits())))
return SDOperand(N, 0);
}
// If this is a load followed by a store to the same location, then the store
// is dead/noop.
if (LoadSDNode *Ld = dyn_cast<LoadSDNode>(Value)) {
if (Ld->getBasePtr() == Ptr && ST->getMemoryVT() == Ld->getMemoryVT() &&
ST->isUnindexed() && !ST->isVolatile() &&
// There can't be any side effects between the load and store, such as
// a call or store.
Chain.reachesChainWithoutSideEffects(SDOperand(Ld, 1))) {
// The store is dead, remove it.
return Chain;
}
}
// If this is an FP_ROUND or TRUNC followed by a store, fold this into a
// truncating store. We can do this even if this is already a truncstore.
if ((Value.getOpcode() == ISD::FP_ROUND || Value.getOpcode() == ISD::TRUNCATE)
&& Value.Val->hasOneUse() && ST->isUnindexed() &&
TLI.isTruncStoreLegal(Value.getOperand(0).getValueType(),
ST->getMemoryVT())) {
return DAG.getTruncStore(Chain, Value.getOperand(0), Ptr, ST->getSrcValue(),
ST->getSrcValueOffset(), ST->getMemoryVT(),
ST->isVolatile(), ST->getAlignment());
}
return SDOperand();
}
SDOperand DAGCombiner::visitINSERT_VECTOR_ELT(SDNode *N) {
SDOperand InVec = N->getOperand(0);
SDOperand InVal = N->getOperand(1);
SDOperand EltNo = N->getOperand(2);
// If the invec is a BUILD_VECTOR and if EltNo is a constant, build a new
// vector with the inserted element.
if (InVec.getOpcode() == ISD::BUILD_VECTOR && isa<ConstantSDNode>(EltNo)) {
unsigned Elt = cast<ConstantSDNode>(EltNo)->getValue();
SmallVector<SDOperand, 8> Ops(InVec.Val->op_begin(), InVec.Val->op_end());
if (Elt < Ops.size())
Ops[Elt] = InVal;
return DAG.getNode(ISD::BUILD_VECTOR, InVec.getValueType(),
&Ops[0], Ops.size());
}
return SDOperand();
}
SDOperand DAGCombiner::visitEXTRACT_VECTOR_ELT(SDNode *N) {
// (vextract (v4f32 load $addr), c) -> (f32 load $addr+c*size)
// (vextract (v4f32 s2v (f32 load $addr)), c) -> (f32 load $addr+c*size)
// (vextract (v4f32 shuffle (load $addr), <1,u,u,u>), 0) -> (f32 load $addr)
// Perform only after legalization to ensure build_vector / vector_shuffle
// optimizations have already been done.
if (!AfterLegalize) return SDOperand();
SDOperand InVec = N->getOperand(0);
SDOperand EltNo = N->getOperand(1);
if (isa<ConstantSDNode>(EltNo)) {
unsigned Elt = cast<ConstantSDNode>(EltNo)->getValue();
bool NewLoad = false;
MVT VT = InVec.getValueType();
MVT EVT = VT.getVectorElementType();
MVT LVT = EVT;
if (InVec.getOpcode() == ISD::BIT_CONVERT) {
MVT BCVT = InVec.getOperand(0).getValueType();
if (!BCVT.isVector() || EVT.bitsGT(BCVT.getVectorElementType()))
return SDOperand();
InVec = InVec.getOperand(0);
EVT = BCVT.getVectorElementType();
NewLoad = true;
}
LoadSDNode *LN0 = NULL;
if (ISD::isNormalLoad(InVec.Val))
LN0 = cast<LoadSDNode>(InVec);
else if (InVec.getOpcode() == ISD::SCALAR_TO_VECTOR &&
InVec.getOperand(0).getValueType() == EVT &&
ISD::isNormalLoad(InVec.getOperand(0).Val)) {
LN0 = cast<LoadSDNode>(InVec.getOperand(0));
} else if (InVec.getOpcode() == ISD::VECTOR_SHUFFLE) {
// (vextract (vector_shuffle (load $addr), v2, <1, u, u, u>), 1)
// =>
// (load $addr+1*size)
unsigned Idx = cast<ConstantSDNode>(InVec.getOperand(2).
getOperand(Elt))->getValue();
unsigned NumElems = InVec.getOperand(2).getNumOperands();
InVec = (Idx < NumElems) ? InVec.getOperand(0) : InVec.getOperand(1);
if (InVec.getOpcode() == ISD::BIT_CONVERT)
InVec = InVec.getOperand(0);
if (ISD::isNormalLoad(InVec.Val)) {
LN0 = cast<LoadSDNode>(InVec);
Elt = (Idx < NumElems) ? Idx : Idx - NumElems;
}
}
if (!LN0 || !LN0->hasOneUse() || LN0->isVolatile())
return SDOperand();
unsigned Align = LN0->getAlignment();
if (NewLoad) {
// Check the resultant load doesn't need a higher alignment than the
// original load.
unsigned NewAlign = TLI.getTargetMachine().getTargetData()->
getABITypeAlignment(LVT.getTypeForMVT());
if (NewAlign > Align || !TLI.isOperationLegal(ISD::LOAD, LVT))
return SDOperand();
Align = NewAlign;
}
SDOperand NewPtr = LN0->getBasePtr();
if (Elt) {
unsigned PtrOff = LVT.getSizeInBits() * Elt / 8;
MVT PtrType = NewPtr.getValueType();
if (TLI.isBigEndian())
PtrOff = VT.getSizeInBits() / 8 - PtrOff;
NewPtr = DAG.getNode(ISD::ADD, PtrType, NewPtr,
DAG.getConstant(PtrOff, PtrType));
}
return DAG.getLoad(LVT, LN0->getChain(), NewPtr,
LN0->getSrcValue(), LN0->getSrcValueOffset(),
LN0->isVolatile(), Align);
}
return SDOperand();
}
SDOperand DAGCombiner::visitBUILD_VECTOR(SDNode *N) {
unsigned NumInScalars = N->getNumOperands();
MVT VT = N->getValueType(0);
unsigned NumElts = VT.getVectorNumElements();
MVT EltType = VT.getVectorElementType();
// Check to see if this is a BUILD_VECTOR of a bunch of EXTRACT_VECTOR_ELT
// operations. If so, and if the EXTRACT_VECTOR_ELT vector inputs come from
// at most two distinct vectors, turn this into a shuffle node.
SDOperand VecIn1, VecIn2;
for (unsigned i = 0; i != NumInScalars; ++i) {
// Ignore undef inputs.
if (N->getOperand(i).getOpcode() == ISD::UNDEF) continue;
// If this input is something other than a EXTRACT_VECTOR_ELT with a
// constant index, bail out.
if (N->getOperand(i).getOpcode() != ISD::EXTRACT_VECTOR_ELT ||
!isa<ConstantSDNode>(N->getOperand(i).getOperand(1))) {
VecIn1 = VecIn2 = SDOperand(0, 0);
break;
}
// If the input vector type disagrees with the result of the build_vector,
// we can't make a shuffle.
SDOperand ExtractedFromVec = N->getOperand(i).getOperand(0);
if (ExtractedFromVec.getValueType() != VT) {
VecIn1 = VecIn2 = SDOperand(0, 0);
break;
}
// Otherwise, remember this. We allow up to two distinct input vectors.
if (ExtractedFromVec == VecIn1 || ExtractedFromVec == VecIn2)
continue;
if (VecIn1.Val == 0) {
VecIn1 = ExtractedFromVec;
} else if (VecIn2.Val == 0) {
VecIn2 = ExtractedFromVec;
} else {
// Too many inputs.
VecIn1 = VecIn2 = SDOperand(0, 0);
break;
}
}
// If everything is good, we can make a shuffle operation.
if (VecIn1.Val) {
SmallVector<SDOperand, 8> BuildVecIndices;
for (unsigned i = 0; i != NumInScalars; ++i) {
if (N->getOperand(i).getOpcode() == ISD::UNDEF) {
BuildVecIndices.push_back(DAG.getNode(ISD::UNDEF, TLI.getPointerTy()));
continue;
}
SDOperand Extract = N->getOperand(i);
// If extracting from the first vector, just use the index directly.
if (Extract.getOperand(0) == VecIn1) {
BuildVecIndices.push_back(Extract.getOperand(1));
continue;
}
// Otherwise, use InIdx + VecSize
unsigned Idx = cast<ConstantSDNode>(Extract.getOperand(1))->getValue();
BuildVecIndices.push_back(DAG.getIntPtrConstant(Idx+NumInScalars));
}
// Add count and size info.
MVT BuildVecVT = MVT::getVectorVT(TLI.getPointerTy(), NumElts);
// Return the new VECTOR_SHUFFLE node.
SDOperand Ops[5];
Ops[0] = VecIn1;
if (VecIn2.Val) {
Ops[1] = VecIn2;
} else {
// Use an undef build_vector as input for the second operand.
std::vector<SDOperand> UnOps(NumInScalars,
DAG.getNode(ISD::UNDEF,
EltType));
Ops[1] = DAG.getNode(ISD::BUILD_VECTOR, VT,
&UnOps[0], UnOps.size());
AddToWorkList(Ops[1].Val);
}
Ops[2] = DAG.getNode(ISD::BUILD_VECTOR, BuildVecVT,
&BuildVecIndices[0], BuildVecIndices.size());
return DAG.getNode(ISD::VECTOR_SHUFFLE, VT, Ops, 3);
}
return SDOperand();
}
SDOperand DAGCombiner::visitCONCAT_VECTORS(SDNode *N) {
// TODO: Check to see if this is a CONCAT_VECTORS of a bunch of
// EXTRACT_SUBVECTOR operations. If so, and if the EXTRACT_SUBVECTOR vector
// inputs come from at most two distinct vectors, turn this into a shuffle
// node.
// If we only have one input vector, we don't need to do any concatenation.
if (N->getNumOperands() == 1) {
return N->getOperand(0);
}
return SDOperand();
}
SDOperand DAGCombiner::visitVECTOR_SHUFFLE(SDNode *N) {
SDOperand ShufMask = N->getOperand(2);
unsigned NumElts = ShufMask.getNumOperands();
// If the shuffle mask is an identity operation on the LHS, return the LHS.
bool isIdentity = true;
for (unsigned i = 0; i != NumElts; ++i) {
if (ShufMask.getOperand(i).getOpcode() != ISD::UNDEF &&
cast<ConstantSDNode>(ShufMask.getOperand(i))->getValue() != i) {
isIdentity = false;
break;
}
}
if (isIdentity) return N->getOperand(0);
// If the shuffle mask is an identity operation on the RHS, return the RHS.
isIdentity = true;
for (unsigned i = 0; i != NumElts; ++i) {
if (ShufMask.getOperand(i).getOpcode() != ISD::UNDEF &&
cast<ConstantSDNode>(ShufMask.getOperand(i))->getValue() != i+NumElts) {
isIdentity = false;
break;
}
}
if (isIdentity) return N->getOperand(1);
// Check if the shuffle is a unary shuffle, i.e. one of the vectors is not
// needed at all.
bool isUnary = true;
bool isSplat = true;
int VecNum = -1;
unsigned BaseIdx = 0;
for (unsigned i = 0; i != NumElts; ++i)
if (ShufMask.getOperand(i).getOpcode() != ISD::UNDEF) {
unsigned Idx = cast<ConstantSDNode>(ShufMask.getOperand(i))->getValue();
int V = (Idx < NumElts) ? 0 : 1;
if (VecNum == -1) {
VecNum = V;
BaseIdx = Idx;
} else {
if (BaseIdx != Idx)
isSplat = false;
if (VecNum != V) {
isUnary = false;
break;
}
}
}
SDOperand N0 = N->getOperand(0);
SDOperand N1 = N->getOperand(1);
// Normalize unary shuffle so the RHS is undef.
if (isUnary && VecNum == 1)
std::swap(N0, N1);
// If it is a splat, check if the argument vector is a build_vector with
// all scalar elements the same.
if (isSplat) {
SDNode *V = N0.Val;
// If this is a bit convert that changes the element type of the vector but
// not the number of vector elements, look through it. Be careful not to
// look though conversions that change things like v4f32 to v2f64.
if (V->getOpcode() == ISD::BIT_CONVERT) {
SDOperand ConvInput = V->getOperand(0);
if (ConvInput.getValueType().getVectorNumElements() == NumElts)
V = ConvInput.Val;
}
if (V->getOpcode() == ISD::BUILD_VECTOR) {
unsigned NumElems = V->getNumOperands();
if (NumElems > BaseIdx) {
SDOperand Base;
bool AllSame = true;
for (unsigned i = 0; i != NumElems; ++i) {
if (V->getOperand(i).getOpcode() != ISD::UNDEF) {
Base = V->getOperand(i);
break;
}
}
// Splat of <u, u, u, u>, return <u, u, u, u>
if (!Base.Val)
return N0;
for (unsigned i = 0; i != NumElems; ++i) {
if (V->getOperand(i) != Base) {
AllSame = false;
break;
}
}
// Splat of <x, x, x, x>, return <x, x, x, x>
if (AllSame)
return N0;
}
}
}
// If it is a unary or the LHS and the RHS are the same node, turn the RHS
// into an undef.
if (isUnary || N0 == N1) {
// Check the SHUFFLE mask, mapping any inputs from the 2nd operand into the
// first operand.
SmallVector<SDOperand, 8> MappedOps;
for (unsigned i = 0; i != NumElts; ++i) {
if (ShufMask.getOperand(i).getOpcode() == ISD::UNDEF ||
cast<ConstantSDNode>(ShufMask.getOperand(i))->getValue() < NumElts) {
MappedOps.push_back(ShufMask.getOperand(i));
} else {
unsigned NewIdx =
cast<ConstantSDNode>(ShufMask.getOperand(i))->getValue() - NumElts;
MappedOps.push_back(DAG.getConstant(NewIdx, MVT::i32));
}
}
ShufMask = DAG.getNode(ISD::BUILD_VECTOR, ShufMask.getValueType(),
&MappedOps[0], MappedOps.size());
AddToWorkList(ShufMask.Val);
return DAG.getNode(ISD::VECTOR_SHUFFLE, N->getValueType(0),
N0,
DAG.getNode(ISD::UNDEF, N->getValueType(0)),
ShufMask);
}
return SDOperand();
}
/// XformToShuffleWithZero - Returns a vector_shuffle if it able to transform
/// an AND to a vector_shuffle with the destination vector and a zero vector.
/// e.g. AND V, <0xffffffff, 0, 0xffffffff, 0>. ==>
/// vector_shuffle V, Zero, <0, 4, 2, 4>
SDOperand DAGCombiner::XformToShuffleWithZero(SDNode *N) {
SDOperand LHS = N->getOperand(0);
SDOperand RHS = N->getOperand(1);
if (N->getOpcode() == ISD::AND) {
if (RHS.getOpcode() == ISD::BIT_CONVERT)
RHS = RHS.getOperand(0);
if (RHS.getOpcode() == ISD::BUILD_VECTOR) {
std::vector<SDOperand> IdxOps;
unsigned NumOps = RHS.getNumOperands();
unsigned NumElts = NumOps;
MVT EVT = RHS.getValueType().getVectorElementType();
for (unsigned i = 0; i != NumElts; ++i) {
SDOperand Elt = RHS.getOperand(i);
if (!isa<ConstantSDNode>(Elt))
return SDOperand();
else if (cast<ConstantSDNode>(Elt)->isAllOnesValue())
IdxOps.push_back(DAG.getConstant(i, EVT));
else if (cast<ConstantSDNode>(Elt)->isNullValue())
IdxOps.push_back(DAG.getConstant(NumElts, EVT));
else
return SDOperand();
}
// Let's see if the target supports this vector_shuffle.
if (!TLI.isVectorClearMaskLegal(IdxOps, EVT, DAG))
return SDOperand();
// Return the new VECTOR_SHUFFLE node.
MVT VT = MVT::getVectorVT(EVT, NumElts);
std::vector<SDOperand> Ops;
LHS = DAG.getNode(ISD::BIT_CONVERT, VT, LHS);
Ops.push_back(LHS);
AddToWorkList(LHS.Val);
std::vector<SDOperand> ZeroOps(NumElts, DAG.getConstant(0, EVT));
Ops.push_back(DAG.getNode(ISD::BUILD_VECTOR, VT,
&ZeroOps[0], ZeroOps.size()));
Ops.push_back(DAG.getNode(ISD::BUILD_VECTOR, VT,
&IdxOps[0], IdxOps.size()));
SDOperand Result = DAG.getNode(ISD::VECTOR_SHUFFLE, VT,
&Ops[0], Ops.size());
if (VT != LHS.getValueType()) {
Result = DAG.getNode(ISD::BIT_CONVERT, LHS.getValueType(), Result);
}
return Result;
}
}
return SDOperand();
}
/// SimplifyVBinOp - Visit a binary vector operation, like ADD.
SDOperand DAGCombiner::SimplifyVBinOp(SDNode *N) {
// After legalize, the target may be depending on adds and other
// binary ops to provide legal ways to construct constants or other
// things. Simplifying them may result in a loss of legality.
if (AfterLegalize) return SDOperand();
MVT VT = N->getValueType(0);
assert(VT.isVector() && "SimplifyVBinOp only works on vectors!");
MVT EltType = VT.getVectorElementType();
SDOperand LHS = N->getOperand(0);
SDOperand RHS = N->getOperand(1);
SDOperand Shuffle = XformToShuffleWithZero(N);
if (Shuffle.Val) return Shuffle;
// If the LHS and RHS are BUILD_VECTOR nodes, see if we can constant fold
// this operation.
if (LHS.getOpcode() == ISD::BUILD_VECTOR &&
RHS.getOpcode() == ISD::BUILD_VECTOR) {
SmallVector<SDOperand, 8> Ops;
for (unsigned i = 0, e = LHS.getNumOperands(); i != e; ++i) {
SDOperand LHSOp = LHS.getOperand(i);
SDOperand RHSOp = RHS.getOperand(i);
// If these two elements can't be folded, bail out.
if ((LHSOp.getOpcode() != ISD::UNDEF &&
LHSOp.getOpcode() != ISD::Constant &&
LHSOp.getOpcode() != ISD::ConstantFP) ||
(RHSOp.getOpcode() != ISD::UNDEF &&
RHSOp.getOpcode() != ISD::Constant &&
RHSOp.getOpcode() != ISD::ConstantFP))
break;
// Can't fold divide by zero.
if (N->getOpcode() == ISD::SDIV || N->getOpcode() == ISD::UDIV ||
N->getOpcode() == ISD::FDIV) {
if ((RHSOp.getOpcode() == ISD::Constant &&
cast<ConstantSDNode>(RHSOp.Val)->isNullValue()) ||
(RHSOp.getOpcode() == ISD::ConstantFP &&
cast<ConstantFPSDNode>(RHSOp.Val)->getValueAPF().isZero()))
break;
}
Ops.push_back(DAG.getNode(N->getOpcode(), EltType, LHSOp, RHSOp));
AddToWorkList(Ops.back().Val);
assert((Ops.back().getOpcode() == ISD::UNDEF ||
Ops.back().getOpcode() == ISD::Constant ||
Ops.back().getOpcode() == ISD::ConstantFP) &&
"Scalar binop didn't fold!");
}
if (Ops.size() == LHS.getNumOperands()) {
MVT VT = LHS.getValueType();
return DAG.getNode(ISD::BUILD_VECTOR, VT, &Ops[0], Ops.size());
}
}
return SDOperand();
}
SDOperand DAGCombiner::SimplifySelect(SDOperand N0, SDOperand N1, SDOperand N2){
assert(N0.getOpcode() ==ISD::SETCC && "First argument must be a SetCC node!");
SDOperand SCC = SimplifySelectCC(N0.getOperand(0), N0.getOperand(1), N1, N2,
cast<CondCodeSDNode>(N0.getOperand(2))->get());
// If we got a simplified select_cc node back from SimplifySelectCC, then
// break it down into a new SETCC node, and a new SELECT node, and then return
// the SELECT node, since we were called with a SELECT node.
if (SCC.Val) {
// Check to see if we got a select_cc back (to turn into setcc/select).
// Otherwise, just return whatever node we got back, like fabs.
if (SCC.getOpcode() == ISD::SELECT_CC) {
SDOperand SETCC = DAG.getNode(ISD::SETCC, N0.getValueType(),
SCC.getOperand(0), SCC.getOperand(1),
SCC.getOperand(4));
AddToWorkList(SETCC.Val);
return DAG.getNode(ISD::SELECT, SCC.getValueType(), SCC.getOperand(2),
SCC.getOperand(3), SETCC);
}
return SCC;
}
return SDOperand();
}
/// SimplifySelectOps - Given a SELECT or a SELECT_CC node, where LHS and RHS
/// are the two values being selected between, see if we can simplify the
/// select. Callers of this should assume that TheSelect is deleted if this
/// returns true. As such, they should return the appropriate thing (e.g. the
/// node) back to the top-level of the DAG combiner loop to avoid it being
/// looked at.
///
bool DAGCombiner::SimplifySelectOps(SDNode *TheSelect, SDOperand LHS,
SDOperand RHS) {
// If this is a select from two identical things, try to pull the operation
// through the select.
if (LHS.getOpcode() == RHS.getOpcode() && LHS.hasOneUse() && RHS.hasOneUse()){
// If this is a load and the token chain is identical, replace the select
// of two loads with a load through a select of the address to load from.
// This triggers in things like "select bool X, 10.0, 123.0" after the FP
// constants have been dropped into the constant pool.
if (LHS.getOpcode() == ISD::LOAD &&
// Do not let this transformation reduce the number of volatile loads.
!cast<LoadSDNode>(LHS)->isVolatile() &&
!cast<LoadSDNode>(RHS)->isVolatile() &&
// Token chains must be identical.
LHS.getOperand(0) == RHS.getOperand(0)) {
LoadSDNode *LLD = cast<LoadSDNode>(LHS);
LoadSDNode *RLD = cast<LoadSDNode>(RHS);
// If this is an EXTLOAD, the VT's must match.
if (LLD->getMemoryVT() == RLD->getMemoryVT()) {
// FIXME: this conflates two src values, discarding one. This is not
// the right thing to do, but nothing uses srcvalues now. When they do,
// turn SrcValue into a list of locations.
SDOperand Addr;
if (TheSelect->getOpcode() == ISD::SELECT) {
// Check that the condition doesn't reach either load. If so, folding
// this will induce a cycle into the DAG.
if (!LLD->isPredecessorOf(TheSelect->getOperand(0).Val) &&
!RLD->isPredecessorOf(TheSelect->getOperand(0).Val)) {
Addr = DAG.getNode(ISD::SELECT, LLD->getBasePtr().getValueType(),
TheSelect->getOperand(0), LLD->getBasePtr(),
RLD->getBasePtr());
}
} else {
// Check that the condition doesn't reach either load. If so, folding
// this will induce a cycle into the DAG.
if (!LLD->isPredecessorOf(TheSelect->getOperand(0).Val) &&
!RLD->isPredecessorOf(TheSelect->getOperand(0).Val) &&
!LLD->isPredecessorOf(TheSelect->getOperand(1).Val) &&
!RLD->isPredecessorOf(TheSelect->getOperand(1).Val)) {
Addr = DAG.getNode(ISD::SELECT_CC, LLD->getBasePtr().getValueType(),
TheSelect->getOperand(0),
TheSelect->getOperand(1),
LLD->getBasePtr(), RLD->getBasePtr(),
TheSelect->getOperand(4));
}
}
if (Addr.Val) {
SDOperand Load;
if (LLD->getExtensionType() == ISD::NON_EXTLOAD)
Load = DAG.getLoad(TheSelect->getValueType(0), LLD->getChain(),
Addr,LLD->getSrcValue(),
LLD->getSrcValueOffset(),
LLD->isVolatile(),
LLD->getAlignment());
else {
Load = DAG.getExtLoad(LLD->getExtensionType(),
TheSelect->getValueType(0),
LLD->getChain(), Addr, LLD->getSrcValue(),
LLD->getSrcValueOffset(),
LLD->getMemoryVT(),
LLD->isVolatile(),
LLD->getAlignment());
}
// Users of the select now use the result of the load.
CombineTo(TheSelect, Load);
// Users of the old loads now use the new load's chain. We know the
// old-load value is dead now.
CombineTo(LHS.Val, Load.getValue(0), Load.getValue(1));
CombineTo(RHS.Val, Load.getValue(0), Load.getValue(1));
return true;
}
}
}
}
return false;
}
SDOperand DAGCombiner::SimplifySelectCC(SDOperand N0, SDOperand N1,
SDOperand N2, SDOperand N3,
ISD::CondCode CC, bool NotExtCompare) {
MVT VT = N2.getValueType();
ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val);
ConstantSDNode *N2C = dyn_cast<ConstantSDNode>(N2.Val);
ConstantSDNode *N3C = dyn_cast<ConstantSDNode>(N3.Val);
// Determine if the condition we're dealing with is constant
SDOperand SCC = SimplifySetCC(TLI.getSetCCResultType(N0), N0, N1, CC, false);
if (SCC.Val) AddToWorkList(SCC.Val);
ConstantSDNode *SCCC = dyn_cast_or_null<ConstantSDNode>(SCC.Val);
// fold select_cc true, x, y -> x
if (SCCC && !SCCC->isNullValue())
return N2;
// fold select_cc false, x, y -> y
if (SCCC && SCCC->isNullValue())
return N3;
// Check to see if we can simplify the select into an fabs node
if (ConstantFPSDNode *CFP = dyn_cast<ConstantFPSDNode>(N1)) {
// Allow either -0.0 or 0.0
if (CFP->getValueAPF().isZero()) {
// select (setg[te] X, +/-0.0), X, fneg(X) -> fabs
if ((CC == ISD::SETGE || CC == ISD::SETGT) &&
N0 == N2 && N3.getOpcode() == ISD::FNEG &&
N2 == N3.getOperand(0))
return DAG.getNode(ISD::FABS, VT, N0);
// select (setl[te] X, +/-0.0), fneg(X), X -> fabs
if ((CC == ISD::SETLT || CC == ISD::SETLE) &&
N0 == N3 && N2.getOpcode() == ISD::FNEG &&
N2.getOperand(0) == N3)
return DAG.getNode(ISD::FABS, VT, N3);
}
}
// Check to see if we can perform the "gzip trick", transforming
// select_cc setlt X, 0, A, 0 -> and (sra X, size(X)-1), A
if (N1C && N3C && N3C->isNullValue() && CC == ISD::SETLT &&
N0.getValueType().isInteger() &&
N2.getValueType().isInteger() &&
(N1C->isNullValue() || // (a < 0) ? b : 0
(N1C->getAPIntValue() == 1 && N0 == N2))) { // (a < 1) ? a : 0
MVT XType = N0.getValueType();
MVT AType = N2.getValueType();
if (XType.bitsGE(AType)) {
// and (sra X, size(X)-1, A) -> "and (srl X, C2), A" iff A is a
// single-bit constant.
if (N2C && ((N2C->getAPIntValue() & (N2C->getAPIntValue()-1)) == 0)) {
unsigned ShCtV = N2C->getAPIntValue().logBase2();
ShCtV = XType.getSizeInBits()-ShCtV-1;
SDOperand ShCt = DAG.getConstant(ShCtV, TLI.getShiftAmountTy());
SDOperand Shift = DAG.getNode(ISD::SRL, XType, N0, ShCt);
AddToWorkList(Shift.Val);
if (XType.bitsGT(AType)) {
Shift = DAG.getNode(ISD::TRUNCATE, AType, Shift);
AddToWorkList(Shift.Val);
}
return DAG.getNode(ISD::AND, AType, Shift, N2);
}
SDOperand Shift = DAG.getNode(ISD::SRA, XType, N0,
DAG.getConstant(XType.getSizeInBits()-1,
TLI.getShiftAmountTy()));
AddToWorkList(Shift.Val);
if (XType.bitsGT(AType)) {
Shift = DAG.getNode(ISD::TRUNCATE, AType, Shift);
AddToWorkList(Shift.Val);
}
return DAG.getNode(ISD::AND, AType, Shift, N2);
}
}
// fold select C, 16, 0 -> shl C, 4
if (N2C && N3C && N3C->isNullValue() && N2C->getAPIntValue().isPowerOf2() &&
TLI.getSetCCResultContents() == TargetLowering::ZeroOrOneSetCCResult) {
// If the caller doesn't want us to simplify this into a zext of a compare,
// don't do it.
if (NotExtCompare && N2C->getAPIntValue() == 1)
return SDOperand();
// Get a SetCC of the condition
// FIXME: Should probably make sure that setcc is legal if we ever have a
// target where it isn't.
SDOperand Temp, SCC;
// cast from setcc result type to select result type
if (AfterLegalize) {
SCC = DAG.getSetCC(TLI.getSetCCResultType(N0), N0, N1, CC);
if (N2.getValueType().bitsLT(SCC.getValueType()))
Temp = DAG.getZeroExtendInReg(SCC, N2.getValueType());
else
Temp = DAG.getNode(ISD::ZERO_EXTEND, N2.getValueType(), SCC);
} else {
SCC = DAG.getSetCC(MVT::i1, N0, N1, CC);
Temp = DAG.getNode(ISD::ZERO_EXTEND, N2.getValueType(), SCC);
}
AddToWorkList(SCC.Val);
AddToWorkList(Temp.Val);
if (N2C->getAPIntValue() == 1)
return Temp;
// shl setcc result by log2 n2c
return DAG.getNode(ISD::SHL, N2.getValueType(), Temp,
DAG.getConstant(N2C->getAPIntValue().logBase2(),
TLI.getShiftAmountTy()));
}
// Check to see if this is the equivalent of setcc
// FIXME: Turn all of these into setcc if setcc if setcc is legal
// otherwise, go ahead with the folds.
if (0 && N3C && N3C->isNullValue() && N2C && (N2C->getAPIntValue() == 1ULL)) {
MVT XType = N0.getValueType();
if (!AfterLegalize ||
TLI.isOperationLegal(ISD::SETCC, TLI.getSetCCResultType(N0))) {
SDOperand Res = DAG.getSetCC(TLI.getSetCCResultType(N0), N0, N1, CC);
if (Res.getValueType() != VT)
Res = DAG.getNode(ISD::ZERO_EXTEND, VT, Res);
return Res;
}
// seteq X, 0 -> srl (ctlz X, log2(size(X)))
if (N1C && N1C->isNullValue() && CC == ISD::SETEQ &&
(!AfterLegalize ||
TLI.isOperationLegal(ISD::CTLZ, XType))) {
SDOperand Ctlz = DAG.getNode(ISD::CTLZ, XType, N0);
return DAG.getNode(ISD::SRL, XType, Ctlz,
DAG.getConstant(Log2_32(XType.getSizeInBits()),
TLI.getShiftAmountTy()));
}
// setgt X, 0 -> srl (and (-X, ~X), size(X)-1)
if (N1C && N1C->isNullValue() && CC == ISD::SETGT) {
SDOperand NegN0 = DAG.getNode(ISD::SUB, XType, DAG.getConstant(0, XType),
N0);
SDOperand NotN0 = DAG.getNode(ISD::XOR, XType, N0,
DAG.getConstant(~0ULL, XType));
return DAG.getNode(ISD::SRL, XType,
DAG.getNode(ISD::AND, XType, NegN0, NotN0),
DAG.getConstant(XType.getSizeInBits()-1,
TLI.getShiftAmountTy()));
}
// setgt X, -1 -> xor (srl (X, size(X)-1), 1)
if (N1C && N1C->isAllOnesValue() && CC == ISD::SETGT) {
SDOperand Sign = DAG.getNode(ISD::SRL, XType, N0,
DAG.getConstant(XType.getSizeInBits()-1,
TLI.getShiftAmountTy()));
return DAG.getNode(ISD::XOR, XType, Sign, DAG.getConstant(1, XType));
}
}
// Check to see if this is an integer abs. select_cc setl[te] X, 0, -X, X ->
// Y = sra (X, size(X)-1); xor (add (X, Y), Y)
if (N1C && N1C->isNullValue() && (CC == ISD::SETLT || CC == ISD::SETLE) &&
N0 == N3 && N2.getOpcode() == ISD::SUB && N0 == N2.getOperand(1) &&
N2.getOperand(0) == N1 && N0.getValueType().isInteger()) {
MVT XType = N0.getValueType();
SDOperand Shift = DAG.getNode(ISD::SRA, XType, N0,
DAG.getConstant(XType.getSizeInBits()-1,
TLI.getShiftAmountTy()));
SDOperand Add = DAG.getNode(ISD::ADD, XType, N0, Shift);
AddToWorkList(Shift.Val);
AddToWorkList(Add.Val);
return DAG.getNode(ISD::XOR, XType, Add, Shift);
}
// Check to see if this is an integer abs. select_cc setgt X, -1, X, -X ->
// Y = sra (X, size(X)-1); xor (add (X, Y), Y)
if (N1C && N1C->isAllOnesValue() && CC == ISD::SETGT &&
N0 == N2 && N3.getOpcode() == ISD::SUB && N0 == N3.getOperand(1)) {
if (ConstantSDNode *SubC = dyn_cast<ConstantSDNode>(N3.getOperand(0))) {
MVT XType = N0.getValueType();
if (SubC->isNullValue() && XType.isInteger()) {
SDOperand Shift = DAG.getNode(ISD::SRA, XType, N0,
DAG.getConstant(XType.getSizeInBits()-1,
TLI.getShiftAmountTy()));
SDOperand Add = DAG.getNode(ISD::ADD, XType, N0, Shift);
AddToWorkList(Shift.Val);
AddToWorkList(Add.Val);
return DAG.getNode(ISD::XOR, XType, Add, Shift);
}
}
}
return SDOperand();
}
/// SimplifySetCC - This is a stub for TargetLowering::SimplifySetCC.
SDOperand DAGCombiner::SimplifySetCC(MVT VT, SDOperand N0,
SDOperand N1, ISD::CondCode Cond,
bool foldBooleans) {
TargetLowering::DAGCombinerInfo
DagCombineInfo(DAG, !AfterLegalize, false, this);
return TLI.SimplifySetCC(VT, N0, N1, Cond, foldBooleans, DagCombineInfo);
}
/// BuildSDIVSequence - Given an ISD::SDIV node expressing a divide by constant,
/// return a DAG expression to select that will generate the same value by
/// multiplying by a magic number. See:
/// <http://the.wall.riscom.net/books/proc/ppc/cwg/code2.html>
SDOperand DAGCombiner::BuildSDIV(SDNode *N) {
std::vector<SDNode*> Built;
SDOperand S = TLI.BuildSDIV(N, DAG, &Built);
for (std::vector<SDNode*>::iterator ii = Built.begin(), ee = Built.end();
ii != ee; ++ii)
AddToWorkList(*ii);
return S;
}
/// BuildUDIVSequence - Given an ISD::UDIV node expressing a divide by constant,
/// return a DAG expression to select that will generate the same value by
/// multiplying by a magic number. See:
/// <http://the.wall.riscom.net/books/proc/ppc/cwg/code2.html>
SDOperand DAGCombiner::BuildUDIV(SDNode *N) {
std::vector<SDNode*> Built;
SDOperand S = TLI.BuildUDIV(N, DAG, &Built);
for (std::vector<SDNode*>::iterator ii = Built.begin(), ee = Built.end();
ii != ee; ++ii)
AddToWorkList(*ii);
return S;
}
/// FindBaseOffset - Return true if base is known not to alias with anything
/// but itself. Provides base object and offset as results.
static bool FindBaseOffset(SDOperand Ptr, SDOperand &Base, int64_t &Offset) {
// Assume it is a primitive operation.
Base = Ptr; Offset = 0;
// If it's an adding a simple constant then integrate the offset.
if (Base.getOpcode() == ISD::ADD) {
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(Base.getOperand(1))) {
Base = Base.getOperand(0);
Offset += C->getValue();
}
}
// If it's any of the following then it can't alias with anything but itself.
return isa<FrameIndexSDNode>(Base) ||
isa<ConstantPoolSDNode>(Base) ||
isa<GlobalAddressSDNode>(Base);
}
/// isAlias - Return true if there is any possibility that the two addresses
/// overlap.
bool DAGCombiner::isAlias(SDOperand Ptr1, int64_t Size1,
const Value *SrcValue1, int SrcValueOffset1,
SDOperand Ptr2, int64_t Size2,
const Value *SrcValue2, int SrcValueOffset2)
{
// If they are the same then they must be aliases.
if (Ptr1 == Ptr2) return true;
// Gather base node and offset information.
SDOperand Base1, Base2;
int64_t Offset1, Offset2;
bool KnownBase1 = FindBaseOffset(Ptr1, Base1, Offset1);
bool KnownBase2 = FindBaseOffset(Ptr2, Base2, Offset2);
// If they have a same base address then...
if (Base1 == Base2) {
// Check to see if the addresses overlap.
return!((Offset1 + Size1) <= Offset2 || (Offset2 + Size2) <= Offset1);
}
// If we know both bases then they can't alias.
if (KnownBase1 && KnownBase2) return false;
if (CombinerGlobalAA) {
// Use alias analysis information.
int64_t MinOffset = std::min(SrcValueOffset1, SrcValueOffset2);
int64_t Overlap1 = Size1 + SrcValueOffset1 - MinOffset;
int64_t Overlap2 = Size2 + SrcValueOffset2 - MinOffset;
AliasAnalysis::AliasResult AAResult =
AA.alias(SrcValue1, Overlap1, SrcValue2, Overlap2);
if (AAResult == AliasAnalysis::NoAlias)
return false;
}
// Otherwise we have to assume they alias.
return true;
}
/// FindAliasInfo - Extracts the relevant alias information from the memory
/// node. Returns true if the operand was a load.
bool DAGCombiner::FindAliasInfo(SDNode *N,
SDOperand &Ptr, int64_t &Size,
const Value *&SrcValue, int &SrcValueOffset) {
if (LoadSDNode *LD = dyn_cast<LoadSDNode>(N)) {
Ptr = LD->getBasePtr();
Size = LD->getMemoryVT().getSizeInBits() >> 3;
SrcValue = LD->getSrcValue();
SrcValueOffset = LD->getSrcValueOffset();
return true;
} else if (StoreSDNode *ST = dyn_cast<StoreSDNode>(N)) {
Ptr = ST->getBasePtr();
Size = ST->getMemoryVT().getSizeInBits() >> 3;
SrcValue = ST->getSrcValue();
SrcValueOffset = ST->getSrcValueOffset();
} else {
assert(0 && "FindAliasInfo expected a memory operand");
}
return false;
}
/// GatherAllAliases - Walk up chain skipping non-aliasing memory nodes,
/// looking for aliasing nodes and adding them to the Aliases vector.
void DAGCombiner::GatherAllAliases(SDNode *N, SDOperand OriginalChain,
SmallVector<SDOperand, 8> &Aliases) {
SmallVector<SDOperand, 8> Chains; // List of chains to visit.
std::set<SDNode *> Visited; // Visited node set.
// Get alias information for node.
SDOperand Ptr;
int64_t Size;
const Value *SrcValue;
int SrcValueOffset;
bool IsLoad = FindAliasInfo(N, Ptr, Size, SrcValue, SrcValueOffset);
// Starting off.
Chains.push_back(OriginalChain);
// Look at each chain and determine if it is an alias. If so, add it to the
// aliases list. If not, then continue up the chain looking for the next
// candidate.
while (!Chains.empty()) {
SDOperand Chain = Chains.back();
Chains.pop_back();
// Don't bother if we've been before.
if (Visited.find(Chain.Val) != Visited.end()) continue;
Visited.insert(Chain.Val);
switch (Chain.getOpcode()) {
case ISD::EntryToken:
// Entry token is ideal chain operand, but handled in FindBetterChain.
break;
case ISD::LOAD:
case ISD::STORE: {
// Get alias information for Chain.
SDOperand OpPtr;
int64_t OpSize;
const Value *OpSrcValue;
int OpSrcValueOffset;
bool IsOpLoad = FindAliasInfo(Chain.Val, OpPtr, OpSize,
OpSrcValue, OpSrcValueOffset);
// If chain is alias then stop here.
if (!(IsLoad && IsOpLoad) &&
isAlias(Ptr, Size, SrcValue, SrcValueOffset,
OpPtr, OpSize, OpSrcValue, OpSrcValueOffset)) {
Aliases.push_back(Chain);
} else {
// Look further up the chain.
Chains.push_back(Chain.getOperand(0));
// Clean up old chain.
AddToWorkList(Chain.Val);
}
break;
}
case ISD::TokenFactor:
// We have to check each of the operands of the token factor, so we queue
// then up. Adding the operands to the queue (stack) in reverse order
// maintains the original order and increases the likelihood that getNode
// will find a matching token factor (CSE.)
for (unsigned n = Chain.getNumOperands(); n;)
Chains.push_back(Chain.getOperand(--n));
// Eliminate the token factor if we can.
AddToWorkList(Chain.Val);
break;
default:
// For all other instructions we will just have to take what we can get.
Aliases.push_back(Chain);
break;
}
}
}
/// FindBetterChain - Walk up chain skipping non-aliasing memory nodes, looking
/// for a better chain (aliasing node.)
SDOperand DAGCombiner::FindBetterChain(SDNode *N, SDOperand OldChain) {
SmallVector<SDOperand, 8> Aliases; // Ops for replacing token factor.
// Accumulate all the aliases to this node.
GatherAllAliases(N, OldChain, Aliases);
if (Aliases.size() == 0) {
// If no operands then chain to entry token.
return DAG.getEntryNode();
} else if (Aliases.size() == 1) {
// If a single operand then chain to it. We don't need to revisit it.
return Aliases[0];
}
// Construct a custom tailored token factor.
SDOperand NewChain = DAG.getNode(ISD::TokenFactor, MVT::Other,
&Aliases[0], Aliases.size());
// Make sure the old chain gets cleaned up.
if (NewChain != OldChain) AddToWorkList(OldChain.Val);
return NewChain;
}
// SelectionDAG::Combine - This is the entry point for the file.
//
void SelectionDAG::Combine(bool RunningAfterLegalize, AliasAnalysis &AA) {
if (!RunningAfterLegalize && ViewDAGCombine1)
viewGraph();
if (RunningAfterLegalize && ViewDAGCombine2)
viewGraph();
/// run - This is the main entry point to this class.
///
DAGCombiner(*this, AA).Run(RunningAfterLegalize);
}
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