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llvm-6502/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
Chris Lattner 4e4b576e2e Implement simple register assignment for inline asms. This allows us to compile: 
int %test(int %A, int %B) {
  %C = call int asm "xyz $0, $1, $2", "=r,r,r"(int %A, int %B)
  ret int %C
}

into:

 (0x8906130, LLVM BB @0x8902220):
        %r2 = OR4 %r3, %r3
        %r3 = OR4 %r4, %r4
        INLINEASM <es:xyz $0, $1, $2>, %r2<def>, %r2, %r3
        %r3 = OR4 %r2, %r2
        BLR

which asmprints as:

_test:
        or r2, r3, r3
        or r3, r4, r4
        xyz $0, $1, $2      ;; need to print the operands now :)
        or r3, r2, r2
        blr


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@25878 91177308-0d34-0410-b5e6-96231b3b80d8
2006-02-01 18:59:47 +00:00

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//===-- SelectionDAGISel.cpp - Implement the SelectionDAGISel class -------===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This implements the SelectionDAGISel class.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "isel"
#include "llvm/CodeGen/SelectionDAGISel.h"
#include "llvm/CodeGen/ScheduleDAG.h"
#include "llvm/CallingConv.h"
#include "llvm/Constants.h"
#include "llvm/DerivedTypes.h"
#include "llvm/Function.h"
#include "llvm/GlobalVariable.h"
#include "llvm/InlineAsm.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
#include "llvm/CodeGen/IntrinsicLowering.h"
#include "llvm/CodeGen/MachineDebugInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/SelectionDAG.h"
#include "llvm/CodeGen/SSARegMap.h"
#include "llvm/Target/MRegisterInfo.h"
#include "llvm/Target/TargetData.h"
#include "llvm/Target/TargetFrameInfo.h"
#include "llvm/Target/TargetInstrInfo.h"
#include "llvm/Target/TargetLowering.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/Support/Debug.h"
#include <map>
#include <set>
#include <iostream>
using namespace llvm;
#ifndef NDEBUG
static cl::opt<bool>
ViewISelDAGs("view-isel-dags", cl::Hidden,
cl::desc("Pop up a window to show isel dags as they are selected"));
static cl::opt<bool>
ViewSchedDAGs("view-sched-dags", cl::Hidden,
cl::desc("Pop up a window to show sched dags as they are processed"));
#else
static const bool ViewISelDAGs = 0;
static const bool ViewSchedDAGs = 0;
#endif
namespace {
cl::opt<SchedHeuristics>
ISHeuristic(
"sched",
cl::desc("Choose scheduling style"),
cl::init(defaultScheduling),
cl::values(
clEnumValN(defaultScheduling, "default",
"Target preferred scheduling style"),
clEnumValN(noScheduling, "none",
"No scheduling: breadth first sequencing"),
clEnumValN(simpleScheduling, "simple",
"Simple two pass scheduling: minimize critical path "
"and maximize processor utilization"),
clEnumValN(simpleNoItinScheduling, "simple-noitin",
"Simple two pass scheduling: Same as simple "
"except using generic latency"),
clEnumValN(listSchedulingBURR, "list-burr",
"Bottom up register reduction list scheduling"),
clEnumValEnd));
} // namespace
namespace llvm {
//===--------------------------------------------------------------------===//
/// FunctionLoweringInfo - This contains information that is global to a
/// function that is used when lowering a region of the function.
class FunctionLoweringInfo {
public:
TargetLowering &TLI;
Function &Fn;
MachineFunction &MF;
SSARegMap *RegMap;
FunctionLoweringInfo(TargetLowering &TLI, Function &Fn,MachineFunction &MF);
/// MBBMap - A mapping from LLVM basic blocks to their machine code entry.
std::map<const BasicBlock*, MachineBasicBlock *> MBBMap;
/// ValueMap - Since we emit code for the function a basic block at a time,
/// we must remember which virtual registers hold the values for
/// cross-basic-block values.
std::map<const Value*, unsigned> ValueMap;
/// StaticAllocaMap - Keep track of frame indices for fixed sized allocas in
/// the entry block. This allows the allocas to be efficiently referenced
/// anywhere in the function.
std::map<const AllocaInst*, int> StaticAllocaMap;
unsigned MakeReg(MVT::ValueType VT) {
return RegMap->createVirtualRegister(TLI.getRegClassFor(VT));
}
unsigned CreateRegForValue(const Value *V) {
MVT::ValueType VT = TLI.getValueType(V->getType());
// The common case is that we will only create one register for this
// value. If we have that case, create and return the virtual register.
unsigned NV = TLI.getNumElements(VT);
if (NV == 1) {
// If we are promoting this value, pick the next largest supported type.
return MakeReg(TLI.getTypeToTransformTo(VT));
}
// If this value is represented with multiple target registers, make sure
// to create enough consequtive registers of the right (smaller) type.
unsigned NT = VT-1; // Find the type to use.
while (TLI.getNumElements((MVT::ValueType)NT) != 1)
--NT;
unsigned R = MakeReg((MVT::ValueType)NT);
for (unsigned i = 1; i != NV; ++i)
MakeReg((MVT::ValueType)NT);
return R;
}
unsigned InitializeRegForValue(const Value *V) {
unsigned &R = ValueMap[V];
assert(R == 0 && "Already initialized this value register!");
return R = CreateRegForValue(V);
}
};
}
/// isUsedOutsideOfDefiningBlock - Return true if this instruction is used by
/// PHI nodes or outside of the basic block that defines it.
static bool isUsedOutsideOfDefiningBlock(Instruction *I) {
if (isa<PHINode>(I)) return true;
BasicBlock *BB = I->getParent();
for (Value::use_iterator UI = I->use_begin(), E = I->use_end(); UI != E; ++UI)
if (cast<Instruction>(*UI)->getParent() != BB || isa<PHINode>(*UI))
return true;
return false;
}
/// isOnlyUsedInEntryBlock - If the specified argument is only used in the
/// entry block, return true.
static bool isOnlyUsedInEntryBlock(Argument *A) {
BasicBlock *Entry = A->getParent()->begin();
for (Value::use_iterator UI = A->use_begin(), E = A->use_end(); UI != E; ++UI)
if (cast<Instruction>(*UI)->getParent() != Entry)
return false; // Use not in entry block.
return true;
}
FunctionLoweringInfo::FunctionLoweringInfo(TargetLowering &tli,
Function &fn, MachineFunction &mf)
: TLI(tli), Fn(fn), MF(mf), RegMap(MF.getSSARegMap()) {
// Create a vreg for each argument register that is not dead and is used
// outside of the entry block for the function.
for (Function::arg_iterator AI = Fn.arg_begin(), E = Fn.arg_end();
AI != E; ++AI)
if (!isOnlyUsedInEntryBlock(AI))
InitializeRegForValue(AI);
// Initialize the mapping of values to registers. This is only set up for
// instruction values that are used outside of the block that defines
// them.
Function::iterator BB = Fn.begin(), EB = Fn.end();
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
if (AllocaInst *AI = dyn_cast<AllocaInst>(I))
if (ConstantUInt *CUI = dyn_cast<ConstantUInt>(AI->getArraySize())) {
const Type *Ty = AI->getAllocatedType();
uint64_t TySize = TLI.getTargetData().getTypeSize(Ty);
unsigned Align =
std::max((unsigned)TLI.getTargetData().getTypeAlignment(Ty),
AI->getAlignment());
// If the alignment of the value is smaller than the size of the value,
// and if the size of the value is particularly small (<= 8 bytes),
// round up to the size of the value for potentially better performance.
//
// FIXME: This could be made better with a preferred alignment hook in
// TargetData. It serves primarily to 8-byte align doubles for X86.
if (Align < TySize && TySize <= 8) Align = TySize;
TySize *= CUI->getValue(); // Get total allocated size.
if (TySize == 0) TySize = 1; // Don't create zero-sized stack objects.
StaticAllocaMap[AI] =
MF.getFrameInfo()->CreateStackObject((unsigned)TySize, Align);
}
for (; BB != EB; ++BB)
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I)
if (!I->use_empty() && isUsedOutsideOfDefiningBlock(I))
if (!isa<AllocaInst>(I) ||
!StaticAllocaMap.count(cast<AllocaInst>(I)))
InitializeRegForValue(I);
// Create an initial MachineBasicBlock for each LLVM BasicBlock in F. This
// also creates the initial PHI MachineInstrs, though none of the input
// operands are populated.
for (BB = Fn.begin(), EB = Fn.end(); BB != EB; ++BB) {
MachineBasicBlock *MBB = new MachineBasicBlock(BB);
MBBMap[BB] = MBB;
MF.getBasicBlockList().push_back(MBB);
// Create Machine PHI nodes for LLVM PHI nodes, lowering them as
// appropriate.
PHINode *PN;
for (BasicBlock::iterator I = BB->begin();
(PN = dyn_cast<PHINode>(I)); ++I)
if (!PN->use_empty()) {
unsigned NumElements =
TLI.getNumElements(TLI.getValueType(PN->getType()));
unsigned PHIReg = ValueMap[PN];
assert(PHIReg &&"PHI node does not have an assigned virtual register!");
for (unsigned i = 0; i != NumElements; ++i)
BuildMI(MBB, TargetInstrInfo::PHI, PN->getNumOperands(), PHIReg+i);
}
}
}
//===----------------------------------------------------------------------===//
/// SelectionDAGLowering - This is the common target-independent lowering
/// implementation that is parameterized by a TargetLowering object.
/// Also, targets can overload any lowering method.
///
namespace llvm {
class SelectionDAGLowering {
MachineBasicBlock *CurMBB;
std::map<const Value*, SDOperand> NodeMap;
/// PendingLoads - Loads are not emitted to the program immediately. We bunch
/// them up and then emit token factor nodes when possible. This allows us to
/// get simple disambiguation between loads without worrying about alias
/// analysis.
std::vector<SDOperand> PendingLoads;
public:
// TLI - This is information that describes the available target features we
// need for lowering. This indicates when operations are unavailable,
// implemented with a libcall, etc.
TargetLowering &TLI;
SelectionDAG &DAG;
const TargetData &TD;
/// FuncInfo - Information about the function as a whole.
///
FunctionLoweringInfo &FuncInfo;
SelectionDAGLowering(SelectionDAG &dag, TargetLowering &tli,
FunctionLoweringInfo &funcinfo)
: TLI(tli), DAG(dag), TD(DAG.getTarget().getTargetData()),
FuncInfo(funcinfo) {
}
/// getRoot - Return the current virtual root of the Selection DAG.
///
SDOperand getRoot() {
if (PendingLoads.empty())
return DAG.getRoot();
if (PendingLoads.size() == 1) {
SDOperand Root = PendingLoads[0];
DAG.setRoot(Root);
PendingLoads.clear();
return Root;
}
// Otherwise, we have to make a token factor node.
SDOperand Root = DAG.getNode(ISD::TokenFactor, MVT::Other, PendingLoads);
PendingLoads.clear();
DAG.setRoot(Root);
return Root;
}
void visit(Instruction &I) { visit(I.getOpcode(), I); }
void visit(unsigned Opcode, User &I) {
switch (Opcode) {
default: assert(0 && "Unknown instruction type encountered!");
abort();
// Build the switch statement using the Instruction.def file.
#define HANDLE_INST(NUM, OPCODE, CLASS) \
case Instruction::OPCODE:return visit##OPCODE((CLASS&)I);
#include "llvm/Instruction.def"
}
}
void setCurrentBasicBlock(MachineBasicBlock *MBB) { CurMBB = MBB; }
SDOperand getIntPtrConstant(uint64_t Val) {
return DAG.getConstant(Val, TLI.getPointerTy());
}
SDOperand getValue(const Value *V) {
SDOperand &N = NodeMap[V];
if (N.Val) return N;
const Type *VTy = V->getType();
MVT::ValueType VT = TLI.getValueType(VTy);
if (Constant *C = const_cast<Constant*>(dyn_cast<Constant>(V)))
if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
visit(CE->getOpcode(), *CE);
assert(N.Val && "visit didn't populate the ValueMap!");
return N;
} else if (GlobalValue *GV = dyn_cast<GlobalValue>(C)) {
return N = DAG.getGlobalAddress(GV, VT);
} else if (isa<ConstantPointerNull>(C)) {
return N = DAG.getConstant(0, TLI.getPointerTy());
} else if (isa<UndefValue>(C)) {
return N = DAG.getNode(ISD::UNDEF, VT);
} else if (ConstantFP *CFP = dyn_cast<ConstantFP>(C)) {
return N = DAG.getConstantFP(CFP->getValue(), VT);
} else if (const PackedType *PTy = dyn_cast<PackedType>(VTy)) {
unsigned NumElements = PTy->getNumElements();
MVT::ValueType PVT = TLI.getValueType(PTy->getElementType());
MVT::ValueType TVT = MVT::getVectorType(PVT, NumElements);
// Now that we know the number and type of the elements, push a
// Constant or ConstantFP node onto the ops list for each element of
// the packed constant.
std::vector<SDOperand> Ops;
if (ConstantPacked *CP = dyn_cast<ConstantPacked>(C)) {
if (MVT::isFloatingPoint(PVT)) {
for (unsigned i = 0; i != NumElements; ++i) {
const ConstantFP *El = cast<ConstantFP>(CP->getOperand(i));
Ops.push_back(DAG.getConstantFP(El->getValue(), PVT));
}
} else {
for (unsigned i = 0; i != NumElements; ++i) {
const ConstantIntegral *El =
cast<ConstantIntegral>(CP->getOperand(i));
Ops.push_back(DAG.getConstant(El->getRawValue(), PVT));
}
}
} else {
assert(isa<ConstantAggregateZero>(C) && "Unknown packed constant!");
SDOperand Op;
if (MVT::isFloatingPoint(PVT))
Op = DAG.getConstantFP(0, PVT);
else
Op = DAG.getConstant(0, PVT);
Ops.assign(NumElements, Op);
}
// Handle the case where we have a 1-element vector, in which
// case we want to immediately turn it into a scalar constant.
if (Ops.size() == 1) {
return N = Ops[0];
} else if (TVT != MVT::Other && TLI.isTypeLegal(TVT)) {
return N = DAG.getNode(ISD::ConstantVec, TVT, Ops);
} else {
// If the packed type isn't legal, then create a ConstantVec node with
// generic Vector type instead.
return N = DAG.getNode(ISD::ConstantVec, MVT::Vector, Ops);
}
} else {
// Canonicalize all constant ints to be unsigned.
return N = DAG.getConstant(cast<ConstantIntegral>(C)->getRawValue(),VT);
}
if (const AllocaInst *AI = dyn_cast<AllocaInst>(V)) {
std::map<const AllocaInst*, int>::iterator SI =
FuncInfo.StaticAllocaMap.find(AI);
if (SI != FuncInfo.StaticAllocaMap.end())
return DAG.getFrameIndex(SI->second, TLI.getPointerTy());
}
std::map<const Value*, unsigned>::const_iterator VMI =
FuncInfo.ValueMap.find(V);
assert(VMI != FuncInfo.ValueMap.end() && "Value not in map!");
unsigned InReg = VMI->second;
// If this type is not legal, make it so now.
MVT::ValueType DestVT = TLI.getTypeToTransformTo(VT);
N = DAG.getCopyFromReg(DAG.getEntryNode(), InReg, DestVT);
if (DestVT < VT) {
// Source must be expanded. This input value is actually coming from the
// register pair VMI->second and VMI->second+1.
N = DAG.getNode(ISD::BUILD_PAIR, VT, N,
DAG.getCopyFromReg(DAG.getEntryNode(), InReg+1, DestVT));
} else {
if (DestVT > VT) { // Promotion case
if (MVT::isFloatingPoint(VT))
N = DAG.getNode(ISD::FP_ROUND, VT, N);
else
N = DAG.getNode(ISD::TRUNCATE, VT, N);
}
}
return N;
}
const SDOperand &setValue(const Value *V, SDOperand NewN) {
SDOperand &N = NodeMap[V];
assert(N.Val == 0 && "Already set a value for this node!");
return N = NewN;
}
unsigned GetAvailableRegister(bool OutReg, bool InReg,
const std::vector<unsigned> &RegChoices,
std::set<unsigned> &OutputRegs,
std::set<unsigned> &InputRegs);
// Terminator instructions.
void visitRet(ReturnInst &I);
void visitBr(BranchInst &I);
void visitUnreachable(UnreachableInst &I) { /* noop */ }
// These all get lowered before this pass.
void visitExtractElement(ExtractElementInst &I) { assert(0 && "TODO"); }
void visitInsertElement(InsertElementInst &I) { assert(0 && "TODO"); }
void visitSwitch(SwitchInst &I) { assert(0 && "TODO"); }
void visitInvoke(InvokeInst &I) { assert(0 && "TODO"); }
void visitUnwind(UnwindInst &I) { assert(0 && "TODO"); }
//
void visitBinary(User &I, unsigned IntOp, unsigned FPOp, unsigned VecOp);
void visitShift(User &I, unsigned Opcode);
void visitAdd(User &I) {
visitBinary(I, ISD::ADD, ISD::FADD, ISD::VADD);
}
void visitSub(User &I);
void visitMul(User &I) {
visitBinary(I, ISD::MUL, ISD::FMUL, ISD::VMUL);
}
void visitDiv(User &I) {
const Type *Ty = I.getType();
visitBinary(I, Ty->isSigned() ? ISD::SDIV : ISD::UDIV, ISD::FDIV, 0);
}
void visitRem(User &I) {
const Type *Ty = I.getType();
visitBinary(I, Ty->isSigned() ? ISD::SREM : ISD::UREM, ISD::FREM, 0);
}
void visitAnd(User &I) { visitBinary(I, ISD::AND, 0, 0); }
void visitOr (User &I) { visitBinary(I, ISD::OR, 0, 0); }
void visitXor(User &I) { visitBinary(I, ISD::XOR, 0, 0); }
void visitShl(User &I) { visitShift(I, ISD::SHL); }
void visitShr(User &I) {
visitShift(I, I.getType()->isUnsigned() ? ISD::SRL : ISD::SRA);
}
void visitSetCC(User &I, ISD::CondCode SignedOpc, ISD::CondCode UnsignedOpc);
void visitSetEQ(User &I) { visitSetCC(I, ISD::SETEQ, ISD::SETEQ); }
void visitSetNE(User &I) { visitSetCC(I, ISD::SETNE, ISD::SETNE); }
void visitSetLE(User &I) { visitSetCC(I, ISD::SETLE, ISD::SETULE); }
void visitSetGE(User &I) { visitSetCC(I, ISD::SETGE, ISD::SETUGE); }
void visitSetLT(User &I) { visitSetCC(I, ISD::SETLT, ISD::SETULT); }
void visitSetGT(User &I) { visitSetCC(I, ISD::SETGT, ISD::SETUGT); }
void visitGetElementPtr(User &I);
void visitCast(User &I);
void visitSelect(User &I);
//
void visitMalloc(MallocInst &I);
void visitFree(FreeInst &I);
void visitAlloca(AllocaInst &I);
void visitLoad(LoadInst &I);
void visitStore(StoreInst &I);
void visitPHI(PHINode &I) { } // PHI nodes are handled specially.
void visitCall(CallInst &I);
void visitInlineAsm(CallInst &I);
const char *visitIntrinsicCall(CallInst &I, unsigned Intrinsic);
void visitVAStart(CallInst &I);
void visitVAArg(VAArgInst &I);
void visitVAEnd(CallInst &I);
void visitVACopy(CallInst &I);
void visitFrameReturnAddress(CallInst &I, bool isFrameAddress);
void visitMemIntrinsic(CallInst &I, unsigned Op);
void visitUserOp1(Instruction &I) {
assert(0 && "UserOp1 should not exist at instruction selection time!");
abort();
}
void visitUserOp2(Instruction &I) {
assert(0 && "UserOp2 should not exist at instruction selection time!");
abort();
}
};
} // end namespace llvm
void SelectionDAGLowering::visitRet(ReturnInst &I) {
if (I.getNumOperands() == 0) {
DAG.setRoot(DAG.getNode(ISD::RET, MVT::Other, getRoot()));
return;
}
std::vector<SDOperand> NewValues;
NewValues.push_back(getRoot());
for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i) {
SDOperand RetOp = getValue(I.getOperand(i));
// If this is an integer return value, we need to promote it ourselves to
// the full width of a register, since LegalizeOp will use ANY_EXTEND rather
// than sign/zero.
if (MVT::isInteger(RetOp.getValueType()) &&
RetOp.getValueType() < MVT::i64) {
MVT::ValueType TmpVT;
if (TLI.getTypeAction(MVT::i32) == TargetLowering::Promote)
TmpVT = TLI.getTypeToTransformTo(MVT::i32);
else
TmpVT = MVT::i32;
if (I.getOperand(i)->getType()->isSigned())
RetOp = DAG.getNode(ISD::SIGN_EXTEND, TmpVT, RetOp);
else
RetOp = DAG.getNode(ISD::ZERO_EXTEND, TmpVT, RetOp);
}
NewValues.push_back(RetOp);
}
DAG.setRoot(DAG.getNode(ISD::RET, MVT::Other, NewValues));
}
void SelectionDAGLowering::visitBr(BranchInst &I) {
// Update machine-CFG edges.
MachineBasicBlock *Succ0MBB = FuncInfo.MBBMap[I.getSuccessor(0)];
// Figure out which block is immediately after the current one.
MachineBasicBlock *NextBlock = 0;
MachineFunction::iterator BBI = CurMBB;
if (++BBI != CurMBB->getParent()->end())
NextBlock = BBI;
if (I.isUnconditional()) {
// If this is not a fall-through branch, emit the branch.
if (Succ0MBB != NextBlock)
DAG.setRoot(DAG.getNode(ISD::BR, MVT::Other, getRoot(),
DAG.getBasicBlock(Succ0MBB)));
} else {
MachineBasicBlock *Succ1MBB = FuncInfo.MBBMap[I.getSuccessor(1)];
SDOperand Cond = getValue(I.getCondition());
if (Succ1MBB == NextBlock) {
// If the condition is false, fall through. This means we should branch
// if the condition is true to Succ #0.
DAG.setRoot(DAG.getNode(ISD::BRCOND, MVT::Other, getRoot(),
Cond, DAG.getBasicBlock(Succ0MBB)));
} else if (Succ0MBB == NextBlock) {
// If the condition is true, fall through. This means we should branch if
// the condition is false to Succ #1. Invert the condition first.
SDOperand True = DAG.getConstant(1, Cond.getValueType());
Cond = DAG.getNode(ISD::XOR, Cond.getValueType(), Cond, True);
DAG.setRoot(DAG.getNode(ISD::BRCOND, MVT::Other, getRoot(),
Cond, DAG.getBasicBlock(Succ1MBB)));
} else {
std::vector<SDOperand> Ops;
Ops.push_back(getRoot());
Ops.push_back(Cond);
Ops.push_back(DAG.getBasicBlock(Succ0MBB));
Ops.push_back(DAG.getBasicBlock(Succ1MBB));
DAG.setRoot(DAG.getNode(ISD::BRCONDTWOWAY, MVT::Other, Ops));
}
}
}
void SelectionDAGLowering::visitSub(User &I) {
// -0.0 - X --> fneg
if (I.getType()->isFloatingPoint()) {
if (ConstantFP *CFP = dyn_cast<ConstantFP>(I.getOperand(0)))
if (CFP->isExactlyValue(-0.0)) {
SDOperand Op2 = getValue(I.getOperand(1));
setValue(&I, DAG.getNode(ISD::FNEG, Op2.getValueType(), Op2));
return;
}
}
visitBinary(I, ISD::SUB, ISD::FSUB, ISD::VSUB);
}
void SelectionDAGLowering::visitBinary(User &I, unsigned IntOp, unsigned FPOp,
unsigned VecOp) {
const Type *Ty = I.getType();
SDOperand Op1 = getValue(I.getOperand(0));
SDOperand Op2 = getValue(I.getOperand(1));
if (Ty->isIntegral()) {
setValue(&I, DAG.getNode(IntOp, Op1.getValueType(), Op1, Op2));
} else if (Ty->isFloatingPoint()) {
setValue(&I, DAG.getNode(FPOp, Op1.getValueType(), Op1, Op2));
} else {
const PackedType *PTy = cast<PackedType>(Ty);
unsigned NumElements = PTy->getNumElements();
MVT::ValueType PVT = TLI.getValueType(PTy->getElementType());
MVT::ValueType TVT = MVT::getVectorType(PVT, NumElements);
// Immediately scalarize packed types containing only one element, so that
// the Legalize pass does not have to deal with them. Similarly, if the
// abstract vector is going to turn into one that the target natively
// supports, generate that type now so that Legalize doesn't have to deal
// with that either. These steps ensure that Legalize only has to handle
// vector types in its Expand case.
unsigned Opc = MVT::isFloatingPoint(PVT) ? FPOp : IntOp;
if (NumElements == 1) {
setValue(&I, DAG.getNode(Opc, PVT, Op1, Op2));
} else if (TVT != MVT::Other && TLI.isTypeLegal(TVT)) {
setValue(&I, DAG.getNode(Opc, TVT, Op1, Op2));
} else {
SDOperand Num = DAG.getConstant(NumElements, MVT::i32);
SDOperand Typ = DAG.getValueType(PVT);
setValue(&I, DAG.getNode(VecOp, MVT::Vector, Op1, Op2, Num, Typ));
}
}
}
void SelectionDAGLowering::visitShift(User &I, unsigned Opcode) {
SDOperand Op1 = getValue(I.getOperand(0));
SDOperand Op2 = getValue(I.getOperand(1));
Op2 = DAG.getNode(ISD::ANY_EXTEND, TLI.getShiftAmountTy(), Op2);
setValue(&I, DAG.getNode(Opcode, Op1.getValueType(), Op1, Op2));
}
void SelectionDAGLowering::visitSetCC(User &I,ISD::CondCode SignedOpcode,
ISD::CondCode UnsignedOpcode) {
SDOperand Op1 = getValue(I.getOperand(0));
SDOperand Op2 = getValue(I.getOperand(1));
ISD::CondCode Opcode = SignedOpcode;
if (I.getOperand(0)->getType()->isUnsigned())
Opcode = UnsignedOpcode;
setValue(&I, DAG.getSetCC(MVT::i1, Op1, Op2, Opcode));
}
void SelectionDAGLowering::visitSelect(User &I) {
SDOperand Cond = getValue(I.getOperand(0));
SDOperand TrueVal = getValue(I.getOperand(1));
SDOperand FalseVal = getValue(I.getOperand(2));
setValue(&I, DAG.getNode(ISD::SELECT, TrueVal.getValueType(), Cond,
TrueVal, FalseVal));
}
void SelectionDAGLowering::visitCast(User &I) {
SDOperand N = getValue(I.getOperand(0));
MVT::ValueType SrcTy = TLI.getValueType(I.getOperand(0)->getType());
MVT::ValueType DestTy = TLI.getValueType(I.getType());
if (N.getValueType() == DestTy) {
setValue(&I, N); // noop cast.
} else if (DestTy == MVT::i1) {
// Cast to bool is a comparison against zero, not truncation to zero.
SDOperand Zero = isInteger(SrcTy) ? DAG.getConstant(0, N.getValueType()) :
DAG.getConstantFP(0.0, N.getValueType());
setValue(&I, DAG.getSetCC(MVT::i1, N, Zero, ISD::SETNE));
} else if (isInteger(SrcTy)) {
if (isInteger(DestTy)) { // Int -> Int cast
if (DestTy < SrcTy) // Truncating cast?
setValue(&I, DAG.getNode(ISD::TRUNCATE, DestTy, N));
else if (I.getOperand(0)->getType()->isSigned())
setValue(&I, DAG.getNode(ISD::SIGN_EXTEND, DestTy, N));
else
setValue(&I, DAG.getNode(ISD::ZERO_EXTEND, DestTy, N));
} else { // Int -> FP cast
if (I.getOperand(0)->getType()->isSigned())
setValue(&I, DAG.getNode(ISD::SINT_TO_FP, DestTy, N));
else
setValue(&I, DAG.getNode(ISD::UINT_TO_FP, DestTy, N));
}
} else {
assert(isFloatingPoint(SrcTy) && "Unknown value type!");
if (isFloatingPoint(DestTy)) { // FP -> FP cast
if (DestTy < SrcTy) // Rounding cast?
setValue(&I, DAG.getNode(ISD::FP_ROUND, DestTy, N));
else
setValue(&I, DAG.getNode(ISD::FP_EXTEND, DestTy, N));
} else { // FP -> Int cast.
if (I.getType()->isSigned())
setValue(&I, DAG.getNode(ISD::FP_TO_SINT, DestTy, N));
else
setValue(&I, DAG.getNode(ISD::FP_TO_UINT, DestTy, N));
}
}
}
void SelectionDAGLowering::visitGetElementPtr(User &I) {
SDOperand N = getValue(I.getOperand(0));
const Type *Ty = I.getOperand(0)->getType();
const Type *UIntPtrTy = TD.getIntPtrType();
for (GetElementPtrInst::op_iterator OI = I.op_begin()+1, E = I.op_end();
OI != E; ++OI) {
Value *Idx = *OI;
if (const StructType *StTy = dyn_cast<StructType>(Ty)) {
unsigned Field = cast<ConstantUInt>(Idx)->getValue();
if (Field) {
// N = N + Offset
uint64_t Offset = TD.getStructLayout(StTy)->MemberOffsets[Field];
N = DAG.getNode(ISD::ADD, N.getValueType(), N,
getIntPtrConstant(Offset));
}
Ty = StTy->getElementType(Field);
} else {
Ty = cast<SequentialType>(Ty)->getElementType();
// If this is a constant subscript, handle it quickly.
if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx)) {
if (CI->getRawValue() == 0) continue;
uint64_t Offs;
if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(CI))
Offs = (int64_t)TD.getTypeSize(Ty)*CSI->getValue();
else
Offs = TD.getTypeSize(Ty)*cast<ConstantUInt>(CI)->getValue();
N = DAG.getNode(ISD::ADD, N.getValueType(), N, getIntPtrConstant(Offs));
continue;
}
// N = N + Idx * ElementSize;
uint64_t ElementSize = TD.getTypeSize(Ty);
SDOperand IdxN = getValue(Idx);
// If the index is smaller or larger than intptr_t, truncate or extend
// it.
if (IdxN.getValueType() < N.getValueType()) {
if (Idx->getType()->isSigned())
IdxN = DAG.getNode(ISD::SIGN_EXTEND, N.getValueType(), IdxN);
else
IdxN = DAG.getNode(ISD::ZERO_EXTEND, N.getValueType(), IdxN);
} else if (IdxN.getValueType() > N.getValueType())
IdxN = DAG.getNode(ISD::TRUNCATE, N.getValueType(), IdxN);
// If this is a multiply by a power of two, turn it into a shl
// immediately. This is a very common case.
if (isPowerOf2_64(ElementSize)) {
unsigned Amt = Log2_64(ElementSize);
IdxN = DAG.getNode(ISD::SHL, N.getValueType(), IdxN,
DAG.getConstant(Amt, TLI.getShiftAmountTy()));
N = DAG.getNode(ISD::ADD, N.getValueType(), N, IdxN);
continue;
}
SDOperand Scale = getIntPtrConstant(ElementSize);
IdxN = DAG.getNode(ISD::MUL, N.getValueType(), IdxN, Scale);
N = DAG.getNode(ISD::ADD, N.getValueType(), N, IdxN);
}
}
setValue(&I, N);
}
void SelectionDAGLowering::visitAlloca(AllocaInst &I) {
// If this is a fixed sized alloca in the entry block of the function,
// allocate it statically on the stack.
if (FuncInfo.StaticAllocaMap.count(&I))
return; // getValue will auto-populate this.
const Type *Ty = I.getAllocatedType();
uint64_t TySize = TLI.getTargetData().getTypeSize(Ty);
unsigned Align = std::max((unsigned)TLI.getTargetData().getTypeAlignment(Ty),
I.getAlignment());
SDOperand AllocSize = getValue(I.getArraySize());
MVT::ValueType IntPtr = TLI.getPointerTy();
if (IntPtr < AllocSize.getValueType())
AllocSize = DAG.getNode(ISD::TRUNCATE, IntPtr, AllocSize);
else if (IntPtr > AllocSize.getValueType())
AllocSize = DAG.getNode(ISD::ZERO_EXTEND, IntPtr, AllocSize);
AllocSize = DAG.getNode(ISD::MUL, IntPtr, AllocSize,
getIntPtrConstant(TySize));
// Handle alignment. If the requested alignment is less than or equal to the
// stack alignment, ignore it and round the size of the allocation up to the
// stack alignment size. If the size is greater than the stack alignment, we
// note this in the DYNAMIC_STACKALLOC node.
unsigned StackAlign =
TLI.getTargetMachine().getFrameInfo()->getStackAlignment();
if (Align <= StackAlign) {
Align = 0;
// Add SA-1 to the size.
AllocSize = DAG.getNode(ISD::ADD, AllocSize.getValueType(), AllocSize,
getIntPtrConstant(StackAlign-1));
// Mask out the low bits for alignment purposes.
AllocSize = DAG.getNode(ISD::AND, AllocSize.getValueType(), AllocSize,
getIntPtrConstant(~(uint64_t)(StackAlign-1)));
}
std::vector<MVT::ValueType> VTs;
VTs.push_back(AllocSize.getValueType());
VTs.push_back(MVT::Other);
std::vector<SDOperand> Ops;
Ops.push_back(getRoot());
Ops.push_back(AllocSize);
Ops.push_back(getIntPtrConstant(Align));
SDOperand DSA = DAG.getNode(ISD::DYNAMIC_STACKALLOC, VTs, Ops);
DAG.setRoot(setValue(&I, DSA).getValue(1));
// Inform the Frame Information that we have just allocated a variable-sized
// object.
CurMBB->getParent()->getFrameInfo()->CreateVariableSizedObject();
}
/// getStringValue - Turn an LLVM constant pointer that eventually points to a
/// global into a string value. Return an empty string if we can't do it.
///
static std::string getStringValue(Value *V, unsigned Offset = 0) {
if (GlobalVariable *GV = dyn_cast<GlobalVariable>(V)) {
if (GV->hasInitializer() && isa<ConstantArray>(GV->getInitializer())) {
ConstantArray *Init = cast<ConstantArray>(GV->getInitializer());
if (Init->isString()) {
std::string Result = Init->getAsString();
if (Offset < Result.size()) {
// If we are pointing INTO The string, erase the beginning...
Result.erase(Result.begin(), Result.begin()+Offset);
// Take off the null terminator, and any string fragments after it.
std::string::size_type NullPos = Result.find_first_of((char)0);
if (NullPos != std::string::npos)
Result.erase(Result.begin()+NullPos, Result.end());
return Result;
}
}
}
} else if (Constant *C = dyn_cast<Constant>(V)) {
if (GlobalValue *GV = dyn_cast<GlobalValue>(C))
return getStringValue(GV, Offset);
else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(C)) {
if (CE->getOpcode() == Instruction::GetElementPtr) {
// Turn a gep into the specified offset.
if (CE->getNumOperands() == 3 &&
cast<Constant>(CE->getOperand(1))->isNullValue() &&
isa<ConstantInt>(CE->getOperand(2))) {
return getStringValue(CE->getOperand(0),
Offset+cast<ConstantInt>(CE->getOperand(2))->getRawValue());
}
}
}
}
return "";
}
void SelectionDAGLowering::visitLoad(LoadInst &I) {
SDOperand Ptr = getValue(I.getOperand(0));
SDOperand Root;
if (I.isVolatile())
Root = getRoot();
else {
// Do not serialize non-volatile loads against each other.
Root = DAG.getRoot();
}
const Type *Ty = I.getType();
SDOperand L;
if (const PackedType *PTy = dyn_cast<PackedType>(Ty)) {
unsigned NumElements = PTy->getNumElements();
MVT::ValueType PVT = TLI.getValueType(PTy->getElementType());
MVT::ValueType TVT = MVT::getVectorType(PVT, NumElements);
// Immediately scalarize packed types containing only one element, so that
// the Legalize pass does not have to deal with them.
if (NumElements == 1) {
L = DAG.getLoad(PVT, Root, Ptr, DAG.getSrcValue(I.getOperand(0)));
} else if (TVT != MVT::Other && TLI.isTypeLegal(TVT)) {
L = DAG.getLoad(TVT, Root, Ptr, DAG.getSrcValue(I.getOperand(0)));
} else {
L = DAG.getVecLoad(NumElements, PVT, Root, Ptr,
DAG.getSrcValue(I.getOperand(0)));
}
} else {
L = DAG.getLoad(TLI.getValueType(Ty), Root, Ptr,
DAG.getSrcValue(I.getOperand(0)));
}
setValue(&I, L);
if (I.isVolatile())
DAG.setRoot(L.getValue(1));
else
PendingLoads.push_back(L.getValue(1));
}
void SelectionDAGLowering::visitStore(StoreInst &I) {
Value *SrcV = I.getOperand(0);
SDOperand Src = getValue(SrcV);
SDOperand Ptr = getValue(I.getOperand(1));
DAG.setRoot(DAG.getNode(ISD::STORE, MVT::Other, getRoot(), Src, Ptr,
DAG.getSrcValue(I.getOperand(1))));
}
/// visitIntrinsicCall - Lower the call to the specified intrinsic function. If
/// we want to emit this as a call to a named external function, return the name
/// otherwise lower it and return null.
const char *
SelectionDAGLowering::visitIntrinsicCall(CallInst &I, unsigned Intrinsic) {
switch (Intrinsic) {
case Intrinsic::vastart: visitVAStart(I); return 0;
case Intrinsic::vaend: visitVAEnd(I); return 0;
case Intrinsic::vacopy: visitVACopy(I); return 0;
case Intrinsic::returnaddress: visitFrameReturnAddress(I, false); return 0;
case Intrinsic::frameaddress: visitFrameReturnAddress(I, true); return 0;
case Intrinsic::setjmp:
return "_setjmp"+!TLI.usesUnderscoreSetJmpLongJmp();
break;
case Intrinsic::longjmp:
return "_longjmp"+!TLI.usesUnderscoreSetJmpLongJmp();
break;
case Intrinsic::memcpy: visitMemIntrinsic(I, ISD::MEMCPY); return 0;
case Intrinsic::memset: visitMemIntrinsic(I, ISD::MEMSET); return 0;
case Intrinsic::memmove: visitMemIntrinsic(I, ISD::MEMMOVE); return 0;
case Intrinsic::readport:
case Intrinsic::readio: {
std::vector<MVT::ValueType> VTs;
VTs.push_back(TLI.getValueType(I.getType()));
VTs.push_back(MVT::Other);
std::vector<SDOperand> Ops;
Ops.push_back(getRoot());
Ops.push_back(getValue(I.getOperand(1)));
SDOperand Tmp = DAG.getNode(Intrinsic == Intrinsic::readport ?
ISD::READPORT : ISD::READIO, VTs, Ops);
setValue(&I, Tmp);
DAG.setRoot(Tmp.getValue(1));
return 0;
}
case Intrinsic::writeport:
case Intrinsic::writeio:
DAG.setRoot(DAG.getNode(Intrinsic == Intrinsic::writeport ?
ISD::WRITEPORT : ISD::WRITEIO, MVT::Other,
getRoot(), getValue(I.getOperand(1)),
getValue(I.getOperand(2))));
return 0;
case Intrinsic::dbg_stoppoint: {
if (TLI.getTargetMachine().getIntrinsicLowering().EmitDebugFunctions())
return "llvm_debugger_stop";
std::string fname = "<unknown>";
std::vector<SDOperand> Ops;
// Input Chain
Ops.push_back(getRoot());
// line number
Ops.push_back(getValue(I.getOperand(2)));
// column
Ops.push_back(getValue(I.getOperand(3)));
// filename/working dir
// Pull the filename out of the the compilation unit.
const GlobalVariable *cunit = dyn_cast<GlobalVariable>(I.getOperand(4));
if (cunit && cunit->hasInitializer()) {
if (ConstantStruct *CS =
dyn_cast<ConstantStruct>(cunit->getInitializer())) {
if (CS->getNumOperands() > 0) {
Ops.push_back(DAG.getString(getStringValue(CS->getOperand(3))));
Ops.push_back(DAG.getString(getStringValue(CS->getOperand(4))));
}
}
}
if (Ops.size() == 5) // Found filename/workingdir.
DAG.setRoot(DAG.getNode(ISD::LOCATION, MVT::Other, Ops));
setValue(&I, DAG.getNode(ISD::UNDEF, TLI.getValueType(I.getType())));
return 0;
}
case Intrinsic::dbg_region_start:
if (TLI.getTargetMachine().getIntrinsicLowering().EmitDebugFunctions())
return "llvm_dbg_region_start";
if (I.getType() != Type::VoidTy)
setValue(&I, DAG.getNode(ISD::UNDEF, TLI.getValueType(I.getType())));
return 0;
case Intrinsic::dbg_region_end:
if (TLI.getTargetMachine().getIntrinsicLowering().EmitDebugFunctions())
return "llvm_dbg_region_end";
if (I.getType() != Type::VoidTy)
setValue(&I, DAG.getNode(ISD::UNDEF, TLI.getValueType(I.getType())));
return 0;
case Intrinsic::dbg_func_start:
if (TLI.getTargetMachine().getIntrinsicLowering().EmitDebugFunctions())
return "llvm_dbg_subprogram";
if (I.getType() != Type::VoidTy)
setValue(&I, DAG.getNode(ISD::UNDEF, TLI.getValueType(I.getType())));
return 0;
case Intrinsic::dbg_declare:
if (I.getType() != Type::VoidTy)
setValue(&I, DAG.getNode(ISD::UNDEF, TLI.getValueType(I.getType())));
return 0;
case Intrinsic::isunordered_f32:
case Intrinsic::isunordered_f64:
setValue(&I, DAG.getSetCC(MVT::i1,getValue(I.getOperand(1)),
getValue(I.getOperand(2)), ISD::SETUO));
return 0;
case Intrinsic::sqrt_f32:
case Intrinsic::sqrt_f64:
setValue(&I, DAG.getNode(ISD::FSQRT,
getValue(I.getOperand(1)).getValueType(),
getValue(I.getOperand(1))));
return 0;
case Intrinsic::pcmarker: {
SDOperand Tmp = getValue(I.getOperand(1));
DAG.setRoot(DAG.getNode(ISD::PCMARKER, MVT::Other, getRoot(), Tmp));
return 0;
}
case Intrinsic::readcyclecounter: {
std::vector<MVT::ValueType> VTs;
VTs.push_back(MVT::i64);
VTs.push_back(MVT::Other);
std::vector<SDOperand> Ops;
Ops.push_back(getRoot());
SDOperand Tmp = DAG.getNode(ISD::READCYCLECOUNTER, VTs, Ops);
setValue(&I, Tmp);
DAG.setRoot(Tmp.getValue(1));
return 0;
}
case Intrinsic::bswap_i16:
case Intrinsic::bswap_i32:
case Intrinsic::bswap_i64:
setValue(&I, DAG.getNode(ISD::BSWAP,
getValue(I.getOperand(1)).getValueType(),
getValue(I.getOperand(1))));
return 0;
case Intrinsic::cttz_i8:
case Intrinsic::cttz_i16:
case Intrinsic::cttz_i32:
case Intrinsic::cttz_i64:
setValue(&I, DAG.getNode(ISD::CTTZ,
getValue(I.getOperand(1)).getValueType(),
getValue(I.getOperand(1))));
return 0;
case Intrinsic::ctlz_i8:
case Intrinsic::ctlz_i16:
case Intrinsic::ctlz_i32:
case Intrinsic::ctlz_i64:
setValue(&I, DAG.getNode(ISD::CTLZ,
getValue(I.getOperand(1)).getValueType(),
getValue(I.getOperand(1))));
return 0;
case Intrinsic::ctpop_i8:
case Intrinsic::ctpop_i16:
case Intrinsic::ctpop_i32:
case Intrinsic::ctpop_i64:
setValue(&I, DAG.getNode(ISD::CTPOP,
getValue(I.getOperand(1)).getValueType(),
getValue(I.getOperand(1))));
return 0;
case Intrinsic::stacksave: {
std::vector<MVT::ValueType> VTs;
VTs.push_back(TLI.getPointerTy());
VTs.push_back(MVT::Other);
std::vector<SDOperand> Ops;
Ops.push_back(getRoot());
SDOperand Tmp = DAG.getNode(ISD::STACKSAVE, VTs, Ops);
setValue(&I, Tmp);
DAG.setRoot(Tmp.getValue(1));
return 0;
}
case Intrinsic::stackrestore: {
SDOperand Tmp = getValue(I.getOperand(1));
DAG.setRoot(DAG.getNode(ISD::STACKRESTORE, MVT::Other, getRoot(), Tmp));
return 0;
}
case Intrinsic::prefetch:
// FIXME: Currently discarding prefetches.
return 0;
default:
std::cerr << I;
assert(0 && "This intrinsic is not implemented yet!");
return 0;
}
}
void SelectionDAGLowering::visitCall(CallInst &I) {
const char *RenameFn = 0;
if (Function *F = I.getCalledFunction()) {
if (F->isExternal())
if (unsigned IID = F->getIntrinsicID()) {
RenameFn = visitIntrinsicCall(I, IID);
if (!RenameFn)
return;
} else { // Not an LLVM intrinsic.
const std::string &Name = F->getName();
if (Name[0] == 'f' && (Name == "fabs" || Name == "fabsf")) {
if (I.getNumOperands() == 2 && // Basic sanity checks.
I.getOperand(1)->getType()->isFloatingPoint() &&
I.getType() == I.getOperand(1)->getType()) {
SDOperand Tmp = getValue(I.getOperand(1));
setValue(&I, DAG.getNode(ISD::FABS, Tmp.getValueType(), Tmp));
return;
}
} else if (Name[0] == 's' && (Name == "sin" || Name == "sinf")) {
if (I.getNumOperands() == 2 && // Basic sanity checks.
I.getOperand(1)->getType()->isFloatingPoint() &&
I.getType() == I.getOperand(1)->getType() &&
TLI.isOperationLegal(ISD::FSIN,
TLI.getValueType(I.getOperand(1)->getType()))) {
SDOperand Tmp = getValue(I.getOperand(1));
setValue(&I, DAG.getNode(ISD::FSIN, Tmp.getValueType(), Tmp));
return;
}
} else if (Name[0] == 'c' && (Name == "cos" || Name == "cosf")) {
if (I.getNumOperands() == 2 && // Basic sanity checks.
I.getOperand(1)->getType()->isFloatingPoint() &&
I.getType() == I.getOperand(1)->getType() &&
TLI.isOperationLegal(ISD::FCOS,
TLI.getValueType(I.getOperand(1)->getType()))) {
SDOperand Tmp = getValue(I.getOperand(1));
setValue(&I, DAG.getNode(ISD::FCOS, Tmp.getValueType(), Tmp));
return;
}
}
}
} else if (isa<InlineAsm>(I.getOperand(0))) {
visitInlineAsm(I);
return;
}
SDOperand Callee;
if (!RenameFn)
Callee = getValue(I.getOperand(0));
else
Callee = DAG.getExternalSymbol(RenameFn, TLI.getPointerTy());
std::vector<std::pair<SDOperand, const Type*> > Args;
Args.reserve(I.getNumOperands());
for (unsigned i = 1, e = I.getNumOperands(); i != e; ++i) {
Value *Arg = I.getOperand(i);
SDOperand ArgNode = getValue(Arg);
Args.push_back(std::make_pair(ArgNode, Arg->getType()));
}
const PointerType *PT = cast<PointerType>(I.getCalledValue()->getType());
const FunctionType *FTy = cast<FunctionType>(PT->getElementType());
std::pair<SDOperand,SDOperand> Result =
TLI.LowerCallTo(getRoot(), I.getType(), FTy->isVarArg(), I.getCallingConv(),
I.isTailCall(), Callee, Args, DAG);
if (I.getType() != Type::VoidTy)
setValue(&I, Result.first);
DAG.setRoot(Result.second);
}
/// GetAvailableRegister - Pick a register from RegChoices that is available
/// for input and/or output as specified by isOutReg/isInReg. If an allocatable
/// register is found, it is returned and added to the specified set of used
/// registers. If not, zero is returned.
unsigned SelectionDAGLowering::
GetAvailableRegister(bool isOutReg, bool isInReg,
const std::vector<unsigned> &RegChoices,
std::set<unsigned> &OutputRegs,
std::set<unsigned> &InputRegs) {
const MRegisterInfo *MRI = DAG.getTarget().getRegisterInfo();
MachineFunction &MF = *CurMBB->getParent();
for (unsigned i = 0, e = RegChoices.size(); i != e; ++i) {
unsigned Reg = RegChoices[i];
// See if this register is available.
if (isOutReg && OutputRegs.count(Reg)) continue; // Already used.
if (isInReg && InputRegs.count(Reg)) continue; // Already used.
// Check to see if this register is allocatable (i.e. don't give out the
// stack pointer).
bool Found = false;
for (MRegisterInfo::regclass_iterator RC = MRI->regclass_begin(),
E = MRI->regclass_end(); !Found && RC != E; ++RC) {
// NOTE: This isn't ideal. In particular, this might allocate the
// frame pointer in functions that need it (due to them not being taken
// out of allocation, because a variable sized allocation hasn't been seen
// yet). This is a slight code pessimization, but should still work.
for (TargetRegisterClass::iterator I = (*RC)->allocation_order_begin(MF),
E = (*RC)->allocation_order_end(MF); I != E; ++I)
if (*I == Reg) {
Found = true;
break;
}
}
if (!Found) continue;
// Okay, this register is good, return it.
if (isOutReg) OutputRegs.insert(Reg); // Mark used.
if (isInReg) InputRegs.insert(Reg); // Mark used.
return Reg;
}
return 0;
}
/// visitInlineAsm - Handle a call to an InlineAsm object.
///
void SelectionDAGLowering::visitInlineAsm(CallInst &I) {
InlineAsm *IA = cast<InlineAsm>(I.getOperand(0));
SDOperand AsmStr = DAG.getTargetExternalSymbol(IA->getAsmString().c_str(),
MVT::Other);
// Note, we treat inline asms both with and without side-effects as the same.
// If an inline asm doesn't have side effects and doesn't access memory, we
// could not choose to not chain it.
bool hasSideEffects = IA->hasSideEffects();
std::vector<InlineAsm::ConstraintInfo> Constraints = IA->ParseConstraints();
/// AsmNodeOperands - A list of pairs. The first element is a register, the
/// second is a bitfield where bit #0 is set if it is a use and bit #1 is set
/// if it is a def of that register.
std::vector<SDOperand> AsmNodeOperands;
AsmNodeOperands.push_back(SDOperand()); // reserve space for input chain
AsmNodeOperands.push_back(AsmStr);
SDOperand Chain = getRoot();
SDOperand Flag;
// Loop over all of the inputs, copying the operand values into the
// appropriate registers and processing the output regs.
unsigned RetValReg = 0;
std::vector<std::pair<unsigned, Value*> > IndirectStoresToEmit;
unsigned OpNum = 1;
bool FoundOutputConstraint = false;
// We fully assign registers here at isel time. This is not optimal, but
// should work. For register classes that correspond to LLVM classes, we
// could let the LLVM RA do its thing, but we currently don't. Do a prepass
// over the constraints, collecting fixed registers that we know we can't use.
std::set<unsigned> OutputRegs, InputRegs;
for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
assert(Constraints[i].Codes.size() == 1 && "Only handles one code so far!");
std::string &ConstraintCode = Constraints[i].Codes[0];
std::vector<unsigned> Regs =
TLI.getRegForInlineAsmConstraint(ConstraintCode);
if (Regs.size() != 1) continue; // Not assigned a fixed reg.
unsigned TheReg = Regs[0];
switch (Constraints[i].Type) {
case InlineAsm::isOutput:
// We can't assign any other output to this register.
OutputRegs.insert(TheReg);
// If this is an early-clobber output, it cannot be assigned to the same
// value as the input reg.
if (Constraints[i].isEarlyClobber)
InputRegs.insert(TheReg);
break;
case InlineAsm::isClobber:
// Clobbered regs cannot be used as inputs or outputs.
InputRegs.insert(TheReg);
OutputRegs.insert(TheReg);
break;
case InlineAsm::isInput:
// We can't assign any other input to this register.
InputRegs.insert(TheReg);
break;
}
}
for (unsigned i = 0, e = Constraints.size(); i != e; ++i) {
assert(Constraints[i].Codes.size() == 1 && "Only handles one code so far!");
std::string &ConstraintCode = Constraints[i].Codes[0];
switch (Constraints[i].Type) {
case InlineAsm::isOutput: {
// Copy the output from the appropriate register.
std::vector<unsigned> Regs =
TLI.getRegForInlineAsmConstraint(ConstraintCode);
// Find a regsister that we can use.
unsigned DestReg;
if (Regs.size() == 1)
DestReg = Regs[0];
else
DestReg = GetAvailableRegister(true, Constraints[i].isEarlyClobber,
Regs, OutputRegs, InputRegs);
assert(DestReg && "Couldn't allocate output reg!");
const Type *OpTy;
if (!Constraints[i].isIndirectOutput) {
assert(!FoundOutputConstraint &&
"Cannot have multiple output constraints yet!");
FoundOutputConstraint = true;
assert(I.getType() != Type::VoidTy && "Bad inline asm!");
RetValReg = DestReg;
OpTy = I.getType();
} else {
IndirectStoresToEmit.push_back(std::make_pair(DestReg,
I.getOperand(OpNum)));
OpTy = I.getOperand(OpNum)->getType();
OpTy = cast<PointerType>(OpTy)->getElementType();
OpNum++; // Consumes a call operand.
}
// Add information to the INLINEASM node to know that this register is
// set.
AsmNodeOperands.push_back(DAG.getRegister(DestReg,
TLI.getValueType(OpTy)));
AsmNodeOperands.push_back(DAG.getConstant(2, MVT::i32)); // ISDEF
break;
}
case InlineAsm::isInput: {
Value *Operand = I.getOperand(OpNum);
const Type *OpTy = Operand->getType();
OpNum++; // Consumes a call operand.
// Copy the input into the appropriate register.
std::vector<unsigned> Regs =
TLI.getRegForInlineAsmConstraint(ConstraintCode);
unsigned SrcReg;
if (Regs.size() == 1)
SrcReg = Regs[0];
else
SrcReg = GetAvailableRegister(false, true, Regs,
OutputRegs, InputRegs);
assert(SrcReg && "Couldn't allocate input reg!");
Chain = DAG.getCopyToReg(Chain, SrcReg, getValue(Operand), Flag);
Flag = Chain.getValue(1);
// Add information to the INLINEASM node to know that this register is
// read.
AsmNodeOperands.push_back(DAG.getRegister(SrcReg,TLI.getValueType(OpTy)));
AsmNodeOperands.push_back(DAG.getConstant(1, MVT::i32)); // ISUSE
break;
}
case InlineAsm::isClobber:
// Nothing to do.
break;
}
}
// Finish up input operands.
AsmNodeOperands[0] = Chain;
if (Flag.Val) AsmNodeOperands.push_back(Flag);
std::vector<MVT::ValueType> VTs;
VTs.push_back(MVT::Other);
VTs.push_back(MVT::Flag);
Chain = DAG.getNode(ISD::INLINEASM, VTs, AsmNodeOperands);
Flag = Chain.getValue(1);
// If this asm returns a register value, copy the result from that register
// and set it as the value of the call.
if (RetValReg) {
SDOperand Val = DAG.getCopyFromReg(Chain, RetValReg,
TLI.getValueType(I.getType()), Flag);
Chain = Val.getValue(1);
Flag = Val.getValue(2);
setValue(&I, Val);
}
std::vector<std::pair<SDOperand, Value*> > StoresToEmit;
// Process indirect outputs, first output all of the flagged copies out of
// physregs.
for (unsigned i = 0, e = IndirectStoresToEmit.size(); i != e; ++i) {
Value *Ptr = IndirectStoresToEmit[i].second;
const Type *Ty = cast<PointerType>(Ptr->getType())->getElementType();
SDOperand Val = DAG.getCopyFromReg(Chain, IndirectStoresToEmit[i].first,
TLI.getValueType(Ty), Flag);
Chain = Val.getValue(1);
Flag = Val.getValue(2);
StoresToEmit.push_back(std::make_pair(Val, Ptr));
}
// Emit the non-flagged stores from the physregs.
std::vector<SDOperand> OutChains;
for (unsigned i = 0, e = StoresToEmit.size(); i != e; ++i)
OutChains.push_back(DAG.getNode(ISD::STORE, MVT::Other, Chain,
StoresToEmit[i].first,
getValue(StoresToEmit[i].second),
DAG.getSrcValue(StoresToEmit[i].second)));
if (!OutChains.empty())
Chain = DAG.getNode(ISD::TokenFactor, MVT::Other, OutChains);
DAG.setRoot(Chain);
}
void SelectionDAGLowering::visitMalloc(MallocInst &I) {
SDOperand Src = getValue(I.getOperand(0));
MVT::ValueType IntPtr = TLI.getPointerTy();
if (IntPtr < Src.getValueType())
Src = DAG.getNode(ISD::TRUNCATE, IntPtr, Src);
else if (IntPtr > Src.getValueType())
Src = DAG.getNode(ISD::ZERO_EXTEND, IntPtr, Src);
// Scale the source by the type size.
uint64_t ElementSize = TD.getTypeSize(I.getType()->getElementType());
Src = DAG.getNode(ISD::MUL, Src.getValueType(),
Src, getIntPtrConstant(ElementSize));
std::vector<std::pair<SDOperand, const Type*> > Args;
Args.push_back(std::make_pair(Src, TLI.getTargetData().getIntPtrType()));
std::pair<SDOperand,SDOperand> Result =
TLI.LowerCallTo(getRoot(), I.getType(), false, CallingConv::C, true,
DAG.getExternalSymbol("malloc", IntPtr),
Args, DAG);
setValue(&I, Result.first); // Pointers always fit in registers
DAG.setRoot(Result.second);
}
void SelectionDAGLowering::visitFree(FreeInst &I) {
std::vector<std::pair<SDOperand, const Type*> > Args;
Args.push_back(std::make_pair(getValue(I.getOperand(0)),
TLI.getTargetData().getIntPtrType()));
MVT::ValueType IntPtr = TLI.getPointerTy();
std::pair<SDOperand,SDOperand> Result =
TLI.LowerCallTo(getRoot(), Type::VoidTy, false, CallingConv::C, true,
DAG.getExternalSymbol("free", IntPtr), Args, DAG);
DAG.setRoot(Result.second);
}
// InsertAtEndOfBasicBlock - This method should be implemented by targets that
// mark instructions with the 'usesCustomDAGSchedInserter' flag. These
// instructions are special in various ways, which require special support to
// insert. The specified MachineInstr is created but not inserted into any
// basic blocks, and the scheduler passes ownership of it to this method.
MachineBasicBlock *TargetLowering::InsertAtEndOfBasicBlock(MachineInstr *MI,
MachineBasicBlock *MBB) {
std::cerr << "If a target marks an instruction with "
"'usesCustomDAGSchedInserter', it must implement "
"TargetLowering::InsertAtEndOfBasicBlock!\n";
abort();
return 0;
}
void SelectionDAGLowering::visitVAStart(CallInst &I) {
DAG.setRoot(DAG.getNode(ISD::VASTART, MVT::Other, getRoot(),
getValue(I.getOperand(1)),
DAG.getSrcValue(I.getOperand(1))));
}
void SelectionDAGLowering::visitVAArg(VAArgInst &I) {
SDOperand V = DAG.getVAArg(TLI.getValueType(I.getType()), getRoot(),
getValue(I.getOperand(0)),
DAG.getSrcValue(I.getOperand(0)));
setValue(&I, V);
DAG.setRoot(V.getValue(1));
}
void SelectionDAGLowering::visitVAEnd(CallInst &I) {
DAG.setRoot(DAG.getNode(ISD::VAEND, MVT::Other, getRoot(),
getValue(I.getOperand(1)),
DAG.getSrcValue(I.getOperand(1))));
}
void SelectionDAGLowering::visitVACopy(CallInst &I) {
DAG.setRoot(DAG.getNode(ISD::VACOPY, MVT::Other, getRoot(),
getValue(I.getOperand(1)),
getValue(I.getOperand(2)),
DAG.getSrcValue(I.getOperand(1)),
DAG.getSrcValue(I.getOperand(2))));
}
// It is always conservatively correct for llvm.returnaddress and
// llvm.frameaddress to return 0.
std::pair<SDOperand, SDOperand>
TargetLowering::LowerFrameReturnAddress(bool isFrameAddr, SDOperand Chain,
unsigned Depth, SelectionDAG &DAG) {
return std::make_pair(DAG.getConstant(0, getPointerTy()), Chain);
}
SDOperand TargetLowering::LowerOperation(SDOperand Op, SelectionDAG &DAG) {
assert(0 && "LowerOperation not implemented for this target!");
abort();
return SDOperand();
}
SDOperand TargetLowering::CustomPromoteOperation(SDOperand Op,
SelectionDAG &DAG) {
assert(0 && "CustomPromoteOperation not implemented for this target!");
abort();
return SDOperand();
}
void SelectionDAGLowering::visitFrameReturnAddress(CallInst &I, bool isFrame) {
unsigned Depth = (unsigned)cast<ConstantUInt>(I.getOperand(1))->getValue();
std::pair<SDOperand,SDOperand> Result =
TLI.LowerFrameReturnAddress(isFrame, getRoot(), Depth, DAG);
setValue(&I, Result.first);
DAG.setRoot(Result.second);
}
void SelectionDAGLowering::visitMemIntrinsic(CallInst &I, unsigned Op) {
#if 0
// If the size of the cpy/move/set is constant (known)
if (ConstantUInt* op3 = dyn_cast<ConstantUInt>(I.getOperand(3))) {
uint64_t size = op3->getValue();
switch (Op) {
case ISD::MEMSET:
if (size <= TLI.getMaxStoresPerMemSet()) {
if (ConstantUInt* op4 = dyn_cast<ConstantUInt>(I.getOperand(4))) {
uint64_t TySize = TLI.getTargetData().getTypeSize(Ty);
uint64_t align = op4.getValue();
while (size > align) {
size -=align;
}
Value *SrcV = I.getOperand(0);
SDOperand Src = getValue(SrcV);
SDOperand Ptr = getValue(I.getOperand(1));
DAG.setRoot(DAG.getNode(ISD::STORE, MVT::Other, getRoot(), Src, Ptr,
DAG.getSrcValue(I.getOperand(1))));
}
break;
}
break; // don't do this optimization, use a normal memset
case ISD::MEMMOVE:
case ISD::MEMCPY:
break; // FIXME: not implemented yet
}
}
#endif
// Non-optimized version
std::vector<SDOperand> Ops;
Ops.push_back(getRoot());
Ops.push_back(getValue(I.getOperand(1)));
Ops.push_back(getValue(I.getOperand(2)));
Ops.push_back(getValue(I.getOperand(3)));
Ops.push_back(getValue(I.getOperand(4)));
DAG.setRoot(DAG.getNode(Op, MVT::Other, Ops));
}
//===----------------------------------------------------------------------===//
// SelectionDAGISel code
//===----------------------------------------------------------------------===//
unsigned SelectionDAGISel::MakeReg(MVT::ValueType VT) {
return RegMap->createVirtualRegister(TLI.getRegClassFor(VT));
}
void SelectionDAGISel::getAnalysisUsage(AnalysisUsage &AU) const {
// FIXME: we only modify the CFG to split critical edges. This
// updates dom and loop info.
}
/// InsertGEPComputeCode - Insert code into BB to compute Ptr+PtrOffset,
/// casting to the type of GEPI.
static Value *InsertGEPComputeCode(Value *&V, BasicBlock *BB, Instruction *GEPI,
Value *Ptr, Value *PtrOffset) {
if (V) return V; // Already computed.
BasicBlock::iterator InsertPt;
if (BB == GEPI->getParent()) {
// If insert into the GEP's block, insert right after the GEP.
InsertPt = GEPI;
++InsertPt;
} else {
// Otherwise, insert at the top of BB, after any PHI nodes
InsertPt = BB->begin();
while (isa<PHINode>(InsertPt)) ++InsertPt;
}
// If Ptr is itself a cast, but in some other BB, emit a copy of the cast into
// BB so that there is only one value live across basic blocks (the cast
// operand).
if (CastInst *CI = dyn_cast<CastInst>(Ptr))
if (CI->getParent() != BB && isa<PointerType>(CI->getOperand(0)->getType()))
Ptr = new CastInst(CI->getOperand(0), CI->getType(), "", InsertPt);
// Add the offset, cast it to the right type.
Ptr = BinaryOperator::createAdd(Ptr, PtrOffset, "", InsertPt);
Ptr = new CastInst(Ptr, GEPI->getType(), "", InsertPt);
return V = Ptr;
}
/// OptimizeGEPExpression - Since we are doing basic-block-at-a-time instruction
/// selection, we want to be a bit careful about some things. In particular, if
/// we have a GEP instruction that is used in a different block than it is
/// defined, the addressing expression of the GEP cannot be folded into loads or
/// stores that use it. In this case, decompose the GEP and move constant
/// indices into blocks that use it.
static void OptimizeGEPExpression(GetElementPtrInst *GEPI,
const TargetData &TD) {
// If this GEP is only used inside the block it is defined in, there is no
// need to rewrite it.
bool isUsedOutsideDefBB = false;
BasicBlock *DefBB = GEPI->getParent();
for (Value::use_iterator UI = GEPI->use_begin(), E = GEPI->use_end();
UI != E; ++UI) {
if (cast<Instruction>(*UI)->getParent() != DefBB) {
isUsedOutsideDefBB = true;
break;
}
}
if (!isUsedOutsideDefBB) return;
// If this GEP has no non-zero constant indices, there is nothing we can do,
// ignore it.
bool hasConstantIndex = false;
for (GetElementPtrInst::op_iterator OI = GEPI->op_begin()+1,
E = GEPI->op_end(); OI != E; ++OI) {
if (ConstantInt *CI = dyn_cast<ConstantInt>(*OI))
if (CI->getRawValue()) {
hasConstantIndex = true;
break;
}
}
// If this is a GEP &Alloca, 0, 0, forward subst the frame index into uses.
if (!hasConstantIndex && !isa<AllocaInst>(GEPI->getOperand(0))) return;
// Otherwise, decompose the GEP instruction into multiplies and adds. Sum the
// constant offset (which we now know is non-zero) and deal with it later.
uint64_t ConstantOffset = 0;
const Type *UIntPtrTy = TD.getIntPtrType();
Value *Ptr = new CastInst(GEPI->getOperand(0), UIntPtrTy, "", GEPI);
const Type *Ty = GEPI->getOperand(0)->getType();
for (GetElementPtrInst::op_iterator OI = GEPI->op_begin()+1,
E = GEPI->op_end(); OI != E; ++OI) {
Value *Idx = *OI;
if (const StructType *StTy = dyn_cast<StructType>(Ty)) {
unsigned Field = cast<ConstantUInt>(Idx)->getValue();
if (Field)
ConstantOffset += TD.getStructLayout(StTy)->MemberOffsets[Field];
Ty = StTy->getElementType(Field);
} else {
Ty = cast<SequentialType>(Ty)->getElementType();
// Handle constant subscripts.
if (ConstantInt *CI = dyn_cast<ConstantInt>(Idx)) {
if (CI->getRawValue() == 0) continue;
if (ConstantSInt *CSI = dyn_cast<ConstantSInt>(CI))
ConstantOffset += (int64_t)TD.getTypeSize(Ty)*CSI->getValue();
else
ConstantOffset+=TD.getTypeSize(Ty)*cast<ConstantUInt>(CI)->getValue();
continue;
}
// Ptr = Ptr + Idx * ElementSize;
// Cast Idx to UIntPtrTy if needed.
Idx = new CastInst(Idx, UIntPtrTy, "", GEPI);
uint64_t ElementSize = TD.getTypeSize(Ty);
// Mask off bits that should not be set.
ElementSize &= ~0ULL >> (64-UIntPtrTy->getPrimitiveSizeInBits());
Constant *SizeCst = ConstantUInt::get(UIntPtrTy, ElementSize);
// Multiply by the element size and add to the base.
Idx = BinaryOperator::createMul(Idx, SizeCst, "", GEPI);
Ptr = BinaryOperator::createAdd(Ptr, Idx, "", GEPI);
}
}
// Make sure that the offset fits in uintptr_t.
ConstantOffset &= ~0ULL >> (64-UIntPtrTy->getPrimitiveSizeInBits());
Constant *PtrOffset = ConstantUInt::get(UIntPtrTy, ConstantOffset);
// Okay, we have now emitted all of the variable index parts to the BB that
// the GEP is defined in. Loop over all of the using instructions, inserting
// an "add Ptr, ConstantOffset" into each block that uses it and update the
// instruction to use the newly computed value, making GEPI dead. When the
// user is a load or store instruction address, we emit the add into the user
// block, otherwise we use a canonical version right next to the gep (these
// won't be foldable as addresses, so we might as well share the computation).
std::map<BasicBlock*,Value*> InsertedExprs;
while (!GEPI->use_empty()) {
Instruction *User = cast<Instruction>(GEPI->use_back());
// If this use is not foldable into the addressing mode, use a version
// emitted in the GEP block.
Value *NewVal;
if (!isa<LoadInst>(User) &&
(!isa<StoreInst>(User) || User->getOperand(0) == GEPI)) {
NewVal = InsertGEPComputeCode(InsertedExprs[DefBB], DefBB, GEPI,
Ptr, PtrOffset);
} else {
// Otherwise, insert the code in the User's block so it can be folded into
// any users in that block.
NewVal = InsertGEPComputeCode(InsertedExprs[User->getParent()],
User->getParent(), GEPI,
Ptr, PtrOffset);
}
User->replaceUsesOfWith(GEPI, NewVal);
}
// Finally, the GEP is dead, remove it.
GEPI->eraseFromParent();
}
bool SelectionDAGISel::runOnFunction(Function &Fn) {
MachineFunction &MF = MachineFunction::construct(&Fn, TLI.getTargetMachine());
RegMap = MF.getSSARegMap();
DEBUG(std::cerr << "\n\n\n=== " << Fn.getName() << "\n");
// First, split all critical edges for PHI nodes with incoming values that are
// constants, this way the load of the constant into a vreg will not be placed
// into MBBs that are used some other way.
//
// In this pass we also look for GEP instructions that are used across basic
// blocks and rewrites them to improve basic-block-at-a-time selection.
//
for (Function::iterator BB = Fn.begin(), E = Fn.end(); BB != E; ++BB) {
PHINode *PN;
BasicBlock::iterator BBI;
for (BBI = BB->begin(); (PN = dyn_cast<PHINode>(BBI)); ++BBI)
for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
if (isa<Constant>(PN->getIncomingValue(i)))
SplitCriticalEdge(PN->getIncomingBlock(i), BB);
for (BasicBlock::iterator E = BB->end(); BBI != E; )
if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(BBI++))
OptimizeGEPExpression(GEPI, TLI.getTargetData());
}
FunctionLoweringInfo FuncInfo(TLI, Fn, MF);
for (Function::iterator I = Fn.begin(), E = Fn.end(); I != E; ++I)
SelectBasicBlock(I, MF, FuncInfo);
return true;
}
SDOperand SelectionDAGISel::
CopyValueToVirtualRegister(SelectionDAGLowering &SDL, Value *V, unsigned Reg) {
SDOperand Op = SDL.getValue(V);
assert((Op.getOpcode() != ISD::CopyFromReg ||
cast<RegisterSDNode>(Op.getOperand(1))->getReg() != Reg) &&
"Copy from a reg to the same reg!");
// If this type is not legal, we must make sure to not create an invalid
// register use.
MVT::ValueType SrcVT = Op.getValueType();
MVT::ValueType DestVT = TLI.getTypeToTransformTo(SrcVT);
SelectionDAG &DAG = SDL.DAG;
if (SrcVT == DestVT) {
return DAG.getCopyToReg(SDL.getRoot(), Reg, Op);
} else if (SrcVT < DestVT) {
// The src value is promoted to the register.
if (MVT::isFloatingPoint(SrcVT))
Op = DAG.getNode(ISD::FP_EXTEND, DestVT, Op);
else
Op = DAG.getNode(ISD::ANY_EXTEND, DestVT, Op);
return DAG.getCopyToReg(SDL.getRoot(), Reg, Op);
} else {
// The src value is expanded into multiple registers.
SDOperand Lo = DAG.getNode(ISD::EXTRACT_ELEMENT, DestVT,
Op, DAG.getConstant(0, MVT::i32));
SDOperand Hi = DAG.getNode(ISD::EXTRACT_ELEMENT, DestVT,
Op, DAG.getConstant(1, MVT::i32));
Op = DAG.getCopyToReg(SDL.getRoot(), Reg, Lo);
return DAG.getCopyToReg(Op, Reg+1, Hi);
}
}
void SelectionDAGISel::
LowerArguments(BasicBlock *BB, SelectionDAGLowering &SDL,
std::vector<SDOperand> &UnorderedChains) {
// If this is the entry block, emit arguments.
Function &F = *BB->getParent();
FunctionLoweringInfo &FuncInfo = SDL.FuncInfo;
SDOperand OldRoot = SDL.DAG.getRoot();
std::vector<SDOperand> Args = TLI.LowerArguments(F, SDL.DAG);
unsigned a = 0;
for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end();
AI != E; ++AI, ++a)
if (!AI->use_empty()) {
SDL.setValue(AI, Args[a]);
// If this argument is live outside of the entry block, insert a copy from
// whereever we got it to the vreg that other BB's will reference it as.
if (FuncInfo.ValueMap.count(AI)) {
SDOperand Copy =
CopyValueToVirtualRegister(SDL, AI, FuncInfo.ValueMap[AI]);
UnorderedChains.push_back(Copy);
}
}
// Next, if the function has live ins that need to be copied into vregs,
// emit the copies now, into the top of the block.
MachineFunction &MF = SDL.DAG.getMachineFunction();
if (MF.livein_begin() != MF.livein_end()) {
SSARegMap *RegMap = MF.getSSARegMap();
const MRegisterInfo &MRI = *MF.getTarget().getRegisterInfo();
for (MachineFunction::livein_iterator LI = MF.livein_begin(),
E = MF.livein_end(); LI != E; ++LI)
if (LI->second)
MRI.copyRegToReg(*MF.begin(), MF.begin()->end(), LI->second,
LI->first, RegMap->getRegClass(LI->second));
}
// Finally, if the target has anything special to do, allow it to do so.
EmitFunctionEntryCode(F, SDL.DAG.getMachineFunction());
}
void SelectionDAGISel::BuildSelectionDAG(SelectionDAG &DAG, BasicBlock *LLVMBB,
std::vector<std::pair<MachineInstr*, unsigned> > &PHINodesToUpdate,
FunctionLoweringInfo &FuncInfo) {
SelectionDAGLowering SDL(DAG, TLI, FuncInfo);
std::vector<SDOperand> UnorderedChains;
// Lower any arguments needed in this block if this is the entry block.
if (LLVMBB == &LLVMBB->getParent()->front())
LowerArguments(LLVMBB, SDL, UnorderedChains);
BB = FuncInfo.MBBMap[LLVMBB];
SDL.setCurrentBasicBlock(BB);
// Lower all of the non-terminator instructions.
for (BasicBlock::iterator I = LLVMBB->begin(), E = --LLVMBB->end();
I != E; ++I)
SDL.visit(*I);
// Ensure that all instructions which are used outside of their defining
// blocks are available as virtual registers.
for (BasicBlock::iterator I = LLVMBB->begin(), E = LLVMBB->end(); I != E;++I)
if (!I->use_empty() && !isa<PHINode>(I)) {
std::map<const Value*, unsigned>::iterator VMI =FuncInfo.ValueMap.find(I);
if (VMI != FuncInfo.ValueMap.end())
UnorderedChains.push_back(
CopyValueToVirtualRegister(SDL, I, VMI->second));
}
// Handle PHI nodes in successor blocks. Emit code into the SelectionDAG to
// ensure constants are generated when needed. Remember the virtual registers
// that need to be added to the Machine PHI nodes as input. We cannot just
// directly add them, because expansion might result in multiple MBB's for one
// BB. As such, the start of the BB might correspond to a different MBB than
// the end.
//
// Emit constants only once even if used by multiple PHI nodes.
std::map<Constant*, unsigned> ConstantsOut;
// Check successor nodes PHI nodes that expect a constant to be available from
// this block.
TerminatorInst *TI = LLVMBB->getTerminator();
for (unsigned succ = 0, e = TI->getNumSuccessors(); succ != e; ++succ) {
BasicBlock *SuccBB = TI->getSuccessor(succ);
MachineBasicBlock::iterator MBBI = FuncInfo.MBBMap[SuccBB]->begin();
PHINode *PN;
// At this point we know that there is a 1-1 correspondence between LLVM PHI
// nodes and Machine PHI nodes, but the incoming operands have not been
// emitted yet.
for (BasicBlock::iterator I = SuccBB->begin();
(PN = dyn_cast<PHINode>(I)); ++I)
if (!PN->use_empty()) {
unsigned Reg;
Value *PHIOp = PN->getIncomingValueForBlock(LLVMBB);
if (Constant *C = dyn_cast<Constant>(PHIOp)) {
unsigned &RegOut = ConstantsOut[C];
if (RegOut == 0) {
RegOut = FuncInfo.CreateRegForValue(C);
UnorderedChains.push_back(
CopyValueToVirtualRegister(SDL, C, RegOut));
}
Reg = RegOut;
} else {
Reg = FuncInfo.ValueMap[PHIOp];
if (Reg == 0) {
assert(isa<AllocaInst>(PHIOp) &&
FuncInfo.StaticAllocaMap.count(cast<AllocaInst>(PHIOp)) &&
"Didn't codegen value into a register!??");
Reg = FuncInfo.CreateRegForValue(PHIOp);
UnorderedChains.push_back(
CopyValueToVirtualRegister(SDL, PHIOp, Reg));
}
}
// Remember that this register needs to added to the machine PHI node as
// the input for this MBB.
unsigned NumElements =
TLI.getNumElements(TLI.getValueType(PN->getType()));
for (unsigned i = 0, e = NumElements; i != e; ++i)
PHINodesToUpdate.push_back(std::make_pair(MBBI++, Reg+i));
}
}
ConstantsOut.clear();
// Turn all of the unordered chains into one factored node.
if (!UnorderedChains.empty()) {
SDOperand Root = SDL.getRoot();
if (Root.getOpcode() != ISD::EntryToken) {
unsigned i = 0, e = UnorderedChains.size();
for (; i != e; ++i) {
assert(UnorderedChains[i].Val->getNumOperands() > 1);
if (UnorderedChains[i].Val->getOperand(0) == Root)
break; // Don't add the root if we already indirectly depend on it.
}
if (i == e)
UnorderedChains.push_back(Root);
}
DAG.setRoot(DAG.getNode(ISD::TokenFactor, MVT::Other, UnorderedChains));
}
// Lower the terminator after the copies are emitted.
SDL.visit(*LLVMBB->getTerminator());
// Make sure the root of the DAG is up-to-date.
DAG.setRoot(SDL.getRoot());
}
void SelectionDAGISel::SelectBasicBlock(BasicBlock *LLVMBB, MachineFunction &MF,
FunctionLoweringInfo &FuncInfo) {
SelectionDAG DAG(TLI, MF, getAnalysisToUpdate<MachineDebugInfo>());
CurDAG = &DAG;
std::vector<std::pair<MachineInstr*, unsigned> > PHINodesToUpdate;
// First step, lower LLVM code to some DAG. This DAG may use operations and
// types that are not supported by the target.
BuildSelectionDAG(DAG, LLVMBB, PHINodesToUpdate, FuncInfo);
// Run the DAG combiner in pre-legalize mode.
DAG.Combine(false);
DEBUG(std::cerr << "Lowered selection DAG:\n");
DEBUG(DAG.dump());
// Second step, hack on the DAG until it only uses operations and types that
// the target supports.
DAG.Legalize();
DEBUG(std::cerr << "Legalized selection DAG:\n");
DEBUG(DAG.dump());
// Run the DAG combiner in post-legalize mode.
DAG.Combine(true);
if (ViewISelDAGs) DAG.viewGraph();
// Third, instruction select all of the operations to machine code, adding the
// code to the MachineBasicBlock.
InstructionSelectBasicBlock(DAG);
DEBUG(std::cerr << "Selected machine code:\n");
DEBUG(BB->dump());
// Next, now that we know what the last MBB the LLVM BB expanded is, update
// PHI nodes in successors.
for (unsigned i = 0, e = PHINodesToUpdate.size(); i != e; ++i) {
MachineInstr *PHI = PHINodesToUpdate[i].first;
assert(PHI->getOpcode() == TargetInstrInfo::PHI &&
"This is not a machine PHI node that we are updating!");
PHI->addRegOperand(PHINodesToUpdate[i].second);
PHI->addMachineBasicBlockOperand(BB);
}
// Finally, add the CFG edges from the last selected MBB to the successor
// MBBs.
TerminatorInst *TI = LLVMBB->getTerminator();
for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) {
MachineBasicBlock *Succ0MBB = FuncInfo.MBBMap[TI->getSuccessor(i)];
BB->addSuccessor(Succ0MBB);
}
}
//===----------------------------------------------------------------------===//
/// ScheduleAndEmitDAG - Pick a safe ordering and emit instructions for each
/// target node in the graph.
void SelectionDAGISel::ScheduleAndEmitDAG(SelectionDAG &DAG) {
if (ViewSchedDAGs) DAG.viewGraph();
ScheduleDAG *SL = NULL;
switch (ISHeuristic) {
default: assert(0 && "Unrecognized scheduling heuristic");
case defaultScheduling:
if (TLI.getSchedulingPreference() == TargetLowering::SchedulingForLatency)
SL = createSimpleDAGScheduler(noScheduling, DAG, BB);
else /* TargetLowering::SchedulingForRegPressure */
SL = createBURRListDAGScheduler(DAG, BB);
break;
case noScheduling:
case simpleScheduling:
case simpleNoItinScheduling:
SL = createSimpleDAGScheduler(ISHeuristic, DAG, BB);
break;
case listSchedulingBURR:
SL = createBURRListDAGScheduler(DAG, BB);
}
BB = SL->Run();
}
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