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llvm-6502/lib/Target/X86/X86ISelDAGToDAG.cpp
Evan Cheng 07e4b00a1a SelectScalarSSELoad should call CanBeFoldedBy as well. 
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@30973 91177308-0d34-0410-b5e6-96231b3b80d8
2006-10-16 06:34:55 +00:00

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//===- X86ISelDAGToDAG.cpp - A DAG pattern matching inst selector for X86 -===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the Evan Cheng and is distributed under
// the University of Illinois Open Source License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines a DAG pattern matching instruction selector for X86,
// converting from a legalized dag to a X86 dag.
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "x86-isel"
#include "X86.h"
#include "X86InstrBuilder.h"
#include "X86ISelLowering.h"
#include "X86RegisterInfo.h"
#include "X86Subtarget.h"
#include "X86TargetMachine.h"
#include "llvm/GlobalValue.h"
#include "llvm/Instructions.h"
#include "llvm/Intrinsics.h"
#include "llvm/Support/CFG.h"
#include "llvm/CodeGen/MachineConstantPool.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/SSARegMap.h"
#include "llvm/CodeGen/SelectionDAGISel.h"
#include "llvm/Target/TargetMachine.h"
#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/MathExtras.h"
#include "llvm/ADT/Statistic.h"
#include <iostream>
#include <queue>
#include <set>
using namespace llvm;
//===----------------------------------------------------------------------===//
// Pattern Matcher Implementation
//===----------------------------------------------------------------------===//
namespace {
/// X86ISelAddressMode - This corresponds to X86AddressMode, but uses
/// SDOperand's instead of register numbers for the leaves of the matched
/// tree.
struct X86ISelAddressMode {
enum {
RegBase,
FrameIndexBase
} BaseType;
struct { // This is really a union, discriminated by BaseType!
SDOperand Reg;
int FrameIndex;
} Base;
bool isRIPRel; // RIP relative?
unsigned Scale;
SDOperand IndexReg;
unsigned Disp;
GlobalValue *GV;
Constant *CP;
const char *ES;
int JT;
unsigned Align; // CP alignment.
X86ISelAddressMode()
: BaseType(RegBase), isRIPRel(false), Scale(1), IndexReg(), Disp(0),
GV(0), CP(0), ES(0), JT(-1), Align(0) {
}
};
}
namespace {
Statistic<>
NumFPKill("x86-codegen", "Number of FP_REG_KILL instructions added");
Statistic<>
NumLoadMoved("x86-codegen", "Number of loads moved below TokenFactor");
//===--------------------------------------------------------------------===//
/// ISel - X86 specific code to select X86 machine instructions for
/// SelectionDAG operations.
///
class VISIBILITY_HIDDEN X86DAGToDAGISel : public SelectionDAGISel {
/// ContainsFPCode - Every instruction we select that uses or defines a FP
/// register should set this to true.
bool ContainsFPCode;
/// FastISel - Enable fast(er) instruction selection.
///
bool FastISel;
/// TM - Keep a reference to X86TargetMachine.
///
X86TargetMachine &TM;
/// X86Lowering - This object fully describes how to lower LLVM code to an
/// X86-specific SelectionDAG.
X86TargetLowering X86Lowering;
/// Subtarget - Keep a pointer to the X86Subtarget around so that we can
/// make the right decision when generating code for different targets.
const X86Subtarget *Subtarget;
/// GlobalBaseReg - keeps track of the virtual register mapped onto global
/// base register.
unsigned GlobalBaseReg;
public:
X86DAGToDAGISel(X86TargetMachine &tm, bool fast)
: SelectionDAGISel(X86Lowering),
ContainsFPCode(false), FastISel(fast), TM(tm),
X86Lowering(*TM.getTargetLowering()),
Subtarget(&TM.getSubtarget<X86Subtarget>()) {}
virtual bool runOnFunction(Function &Fn) {
// Make sure we re-emit a set of the global base reg if necessary
GlobalBaseReg = 0;
return SelectionDAGISel::runOnFunction(Fn);
}
virtual const char *getPassName() const {
return "X86 DAG->DAG Instruction Selection";
}
/// InstructionSelectBasicBlock - This callback is invoked by
/// SelectionDAGISel when it has created a SelectionDAG for us to codegen.
virtual void InstructionSelectBasicBlock(SelectionDAG &DAG);
virtual void EmitFunctionEntryCode(Function &Fn, MachineFunction &MF);
virtual bool CanBeFoldedBy(SDNode *N, SDNode *U, SDNode *Root);
// Include the pieces autogenerated from the target description.
#include "X86GenDAGISel.inc"
private:
SDNode *Select(SDOperand N);
bool MatchAddress(SDOperand N, X86ISelAddressMode &AM, bool isRoot = true);
bool SelectAddr(SDOperand N, SDOperand &Base, SDOperand &Scale,
SDOperand &Index, SDOperand &Disp);
bool SelectLEAAddr(SDOperand N, SDOperand &Base, SDOperand &Scale,
SDOperand &Index, SDOperand &Disp);
bool SelectScalarSSELoad(SDOperand Root, SDOperand Pred,
SDOperand N, SDOperand &Base, SDOperand &Scale,
SDOperand &Index, SDOperand &Disp,
SDOperand &InChain, SDOperand &OutChain);
bool TryFoldLoad(SDOperand P, SDOperand N,
SDOperand &Base, SDOperand &Scale,
SDOperand &Index, SDOperand &Disp);
void InstructionSelectPreprocess(SelectionDAG &DAG);
/// SelectInlineAsmMemoryOperand - Implement addressing mode selection for
/// inline asm expressions.
virtual bool SelectInlineAsmMemoryOperand(const SDOperand &Op,
char ConstraintCode,
std::vector<SDOperand> &OutOps,
SelectionDAG &DAG);
void EmitSpecialCodeForMain(MachineBasicBlock *BB, MachineFrameInfo *MFI);
inline void getAddressOperands(X86ISelAddressMode &AM, SDOperand &Base,
SDOperand &Scale, SDOperand &Index,
SDOperand &Disp) {
Base = (AM.BaseType == X86ISelAddressMode::FrameIndexBase) ?
CurDAG->getTargetFrameIndex(AM.Base.FrameIndex, TLI.getPointerTy()) :
AM.Base.Reg;
Scale = getI8Imm(AM.Scale);
Index = AM.IndexReg;
// These are 32-bit even in 64-bit mode since RIP relative offset
// is 32-bit.
if (AM.GV)
Disp = CurDAG->getTargetGlobalAddress(AM.GV, MVT::i32, AM.Disp);
else if (AM.CP)
Disp = CurDAG->getTargetConstantPool(AM.CP, MVT::i32, AM.Align, AM.Disp);
else if (AM.ES)
Disp = CurDAG->getTargetExternalSymbol(AM.ES, MVT::i32);
else if (AM.JT != -1)
Disp = CurDAG->getTargetJumpTable(AM.JT, MVT::i32);
else
Disp = getI32Imm(AM.Disp);
}
/// getI8Imm - Return a target constant with the specified value, of type
/// i8.
inline SDOperand getI8Imm(unsigned Imm) {
return CurDAG->getTargetConstant(Imm, MVT::i8);
}
/// getI16Imm - Return a target constant with the specified value, of type
/// i16.
inline SDOperand getI16Imm(unsigned Imm) {
return CurDAG->getTargetConstant(Imm, MVT::i16);
}
/// getI32Imm - Return a target constant with the specified value, of type
/// i32.
inline SDOperand getI32Imm(unsigned Imm) {
return CurDAG->getTargetConstant(Imm, MVT::i32);
}
/// getGlobalBaseReg - insert code into the entry mbb to materialize the PIC
/// base register. Return the virtual register that holds this value.
SDNode *getGlobalBaseReg();
#ifndef NDEBUG
unsigned Indent;
#endif
};
}
static SDNode *findFlagUse(SDNode *N) {
unsigned FlagResNo = N->getNumValues()-1;
for (SDNode::use_iterator I = N->use_begin(), E = N->use_end(); I != E; ++I) {
SDNode *User = *I;
for (unsigned i = 0, e = User->getNumOperands(); i != e; ++i) {
SDOperand Op = User->getOperand(i);
if (Op.Val == N && Op.ResNo == FlagResNo)
return User;
}
}
return NULL;
}
static void findNonImmUse(SDNode *Use, SDNode* Def, SDNode *ImmedUse,
SDNode *Root, SDNode *Skip, bool &found,
std::set<SDNode *> &Visited) {
if (found ||
Use->getNodeId() > Def->getNodeId() ||
!Visited.insert(Use).second)
return;
for (unsigned i = 0, e = Use->getNumOperands(); !found && i != e; ++i) {
SDNode *N = Use->getOperand(i).Val;
if (N == Skip)
continue;
if (N == Def) {
if (Use == ImmedUse)
continue; // Immediate use is ok.
if (Use == Root) {
assert(Use->getOpcode() == ISD::STORE ||
Use->getOpcode() == X86ISD::CMP);
continue;
}
found = true;
break;
}
findNonImmUse(N, Def, ImmedUse, Root, Skip, found, Visited);
}
}
/// isNonImmUse - Start searching from Root up the DAG to check is Def can
/// be reached. Return true if that's the case. However, ignore direct uses
/// by ImmedUse (which would be U in the example illustrated in
/// CanBeFoldedBy) and by Root (which can happen in the store case).
/// FIXME: to be really generic, we should allow direct use by any node
/// that is being folded. But realisticly since we only fold loads which
/// have one non-chain use, we only need to watch out for load/op/store
/// and load/op/cmp case where the root (store / cmp) may reach the load via
/// its chain operand.
static inline bool isNonImmUse(SDNode *Root, SDNode *Def, SDNode *ImmedUse,
SDNode *Skip = NULL) {
std::set<SDNode *> Visited;
bool found = false;
findNonImmUse(Root, Def, ImmedUse, Root, Skip, found, Visited);
return found;
}
bool X86DAGToDAGISel::CanBeFoldedBy(SDNode *N, SDNode *U, SDNode *Root) {
if (FastISel) return false;
// If U use can somehow reach N through another path then U can't fold N or
// it will create a cycle. e.g. In the following diagram, U can reach N
// through X. If N is folded into into U, then X is both a predecessor and
// a successor of U.
//
// [ N ]
// ^ ^
// | |
// / \---
// / [X]
// | ^
// [U]--------|
if (isNonImmUse(Root, N, U))
return false;
// If U produces a flag, then it gets (even more) interesting. Since it
// would have been "glued" together with its flag use, we need to check if
// it might reach N:
//
// [ N ]
// ^ ^
// | |
// [U] \--
// ^ [TF]
// | ^
// | |
// \ /
// [FU]
//
// If FU (flag use) indirectly reach N (the load), and U fold N (call it
// NU), then TF is a predecessor of FU and a successor of NU. But since
// NU and FU are flagged together, this effectively creates a cycle.
bool HasFlagUse = false;
MVT::ValueType VT = Root->getValueType(Root->getNumValues()-1);
while ((VT == MVT::Flag && !Root->use_empty())) {
SDNode *FU = findFlagUse(Root);
if (FU == NULL)
break;
else {
Root = FU;
HasFlagUse = true;
}
VT = Root->getValueType(Root->getNumValues()-1);
}
if (HasFlagUse)
return !isNonImmUse(Root, N, Root, U);
return true;
}
/// MoveBelowTokenFactor - Replace TokenFactor operand with load's chain operand
/// and move load below the TokenFactor. Replace store's chain operand with
/// load's chain result.
static void MoveBelowTokenFactor(SelectionDAG &DAG, SDOperand Load,
SDOperand Store, SDOperand TF) {
std::vector<SDOperand> Ops;
for (unsigned i = 0, e = TF.Val->getNumOperands(); i != e; ++i)
if (Load.Val == TF.Val->getOperand(i).Val)
Ops.push_back(Load.Val->getOperand(0));
else
Ops.push_back(TF.Val->getOperand(i));
DAG.UpdateNodeOperands(TF, &Ops[0], Ops.size());
DAG.UpdateNodeOperands(Load, TF, Load.getOperand(1), Load.getOperand(2));
DAG.UpdateNodeOperands(Store, Load.getValue(1), Store.getOperand(1),
Store.getOperand(2), Store.getOperand(3));
}
/// InstructionSelectPreprocess - Preprocess the DAG to allow the instruction
/// selector to pick more load-modify-store instructions. This is a common
/// case:
///
/// [Load chain]
/// ^
/// |
/// [Load]
/// ^ ^
/// | |
/// / \-
/// / |
/// [TokenFactor] [Op]
/// ^ ^
/// | |
/// \ /
/// \ /
/// [Store]
///
/// The fact the store's chain operand != load's chain will prevent the
/// (store (op (load))) instruction from being selected. We can transform it to:
///
/// [Load chain]
/// ^
/// |
/// [TokenFactor]
/// ^
/// |
/// [Load]
/// ^ ^
/// | |
/// | \-
/// | |
/// | [Op]
/// | ^
/// | |
/// \ /
/// \ /
/// [Store]
void X86DAGToDAGISel::InstructionSelectPreprocess(SelectionDAG &DAG) {
for (SelectionDAG::allnodes_iterator I = DAG.allnodes_begin(),
E = DAG.allnodes_end(); I != E; ++I) {
if (!ISD::isNON_TRUNCStore(I))
continue;
SDOperand Chain = I->getOperand(0);
if (Chain.Val->getOpcode() != ISD::TokenFactor)
continue;
SDOperand N1 = I->getOperand(1);
SDOperand N2 = I->getOperand(2);
if (MVT::isFloatingPoint(N1.getValueType()) ||
MVT::isVector(N1.getValueType()) ||
!N1.hasOneUse())
continue;
bool RModW = false;
SDOperand Load;
unsigned Opcode = N1.Val->getOpcode();
switch (Opcode) {
case ISD::ADD:
case ISD::MUL:
case ISD::AND:
case ISD::OR:
case ISD::XOR:
case ISD::ADDC:
case ISD::ADDE: {
SDOperand N10 = N1.getOperand(0);
SDOperand N11 = N1.getOperand(1);
if (ISD::isNON_EXTLoad(N10.Val))
RModW = true;
else if (ISD::isNON_EXTLoad(N11.Val)) {
RModW = true;
std::swap(N10, N11);
}
RModW = RModW && N10.Val->isOperand(Chain.Val) && N10.hasOneUse() &&
(N10.getOperand(1) == N2) &&
(N10.Val->getValueType(0) == N1.getValueType());
if (RModW)
Load = N10;
break;
}
case ISD::SUB:
case ISD::SHL:
case ISD::SRA:
case ISD::SRL:
case ISD::ROTL:
case ISD::ROTR:
case ISD::SUBC:
case ISD::SUBE:
case X86ISD::SHLD:
case X86ISD::SHRD: {
SDOperand N10 = N1.getOperand(0);
if (ISD::isNON_EXTLoad(N10.Val))
RModW = N10.Val->isOperand(Chain.Val) && N10.hasOneUse() &&
(N10.getOperand(1) == N2) &&
(N10.Val->getValueType(0) == N1.getValueType());
if (RModW)
Load = N10;
break;
}
}
if (RModW) {
MoveBelowTokenFactor(DAG, Load, SDOperand(I, 0), Chain);
++NumLoadMoved;
}
}
}
/// InstructionSelectBasicBlock - This callback is invoked by SelectionDAGISel
/// when it has created a SelectionDAG for us to codegen.
void X86DAGToDAGISel::InstructionSelectBasicBlock(SelectionDAG &DAG) {
DEBUG(BB->dump());
MachineFunction::iterator FirstMBB = BB;
if (!FastISel)
InstructionSelectPreprocess(DAG);
// Codegen the basic block.
#ifndef NDEBUG
DEBUG(std::cerr << "===== Instruction selection begins:\n");
Indent = 0;
#endif
DAG.setRoot(SelectRoot(DAG.getRoot()));
#ifndef NDEBUG
DEBUG(std::cerr << "===== Instruction selection ends:\n");
#endif
DAG.RemoveDeadNodes();
// Emit machine code to BB.
ScheduleAndEmitDAG(DAG);
// If we are emitting FP stack code, scan the basic block to determine if this
// block defines any FP values. If so, put an FP_REG_KILL instruction before
// the terminator of the block.
if (!Subtarget->hasSSE2()) {
// Note that FP stack instructions *are* used in SSE code when returning
// values, but these are not live out of the basic block, so we don't need
// an FP_REG_KILL in this case either.
bool ContainsFPCode = false;
// Scan all of the machine instructions in these MBBs, checking for FP
// stores.
MachineFunction::iterator MBBI = FirstMBB;
do {
for (MachineBasicBlock::iterator I = MBBI->begin(), E = MBBI->end();
!ContainsFPCode && I != E; ++I) {
for (unsigned op = 0, e = I->getNumOperands(); op != e; ++op) {
if (I->getOperand(op).isRegister() && I->getOperand(op).isDef() &&
MRegisterInfo::isVirtualRegister(I->getOperand(op).getReg()) &&
RegMap->getRegClass(I->getOperand(0).getReg()) ==
X86::RFPRegisterClass) {
ContainsFPCode = true;
break;
}
}
}
} while (!ContainsFPCode && &*(MBBI++) != BB);
// Check PHI nodes in successor blocks. These PHI's will be lowered to have
// a copy of the input value in this block.
if (!ContainsFPCode) {
// Final check, check LLVM BB's that are successors to the LLVM BB
// corresponding to BB for FP PHI nodes.
const BasicBlock *LLVMBB = BB->getBasicBlock();
const PHINode *PN;
for (succ_const_iterator SI = succ_begin(LLVMBB), E = succ_end(LLVMBB);
!ContainsFPCode && SI != E; ++SI) {
for (BasicBlock::const_iterator II = SI->begin();
(PN = dyn_cast<PHINode>(II)); ++II) {
if (PN->getType()->isFloatingPoint()) {
ContainsFPCode = true;
break;
}
}
}
}
// Finally, if we found any FP code, emit the FP_REG_KILL instruction.
if (ContainsFPCode) {
BuildMI(*BB, BB->getFirstTerminator(), X86::FP_REG_KILL, 0);
++NumFPKill;
}
}
}
/// EmitSpecialCodeForMain - Emit any code that needs to be executed only in
/// the main function.
void X86DAGToDAGISel::EmitSpecialCodeForMain(MachineBasicBlock *BB,
MachineFrameInfo *MFI) {
if (Subtarget->isTargetCygwin())
BuildMI(BB, X86::CALLpcrel32, 1).addExternalSymbol("__main");
// Switch the FPU to 64-bit precision mode for better compatibility and speed.
int CWFrameIdx = MFI->CreateStackObject(2, 2);
addFrameReference(BuildMI(BB, X86::FNSTCW16m, 4), CWFrameIdx);
// Set the high part to be 64-bit precision.
addFrameReference(BuildMI(BB, X86::MOV8mi, 5),
CWFrameIdx, 1).addImm(2);
// Reload the modified control word now.
addFrameReference(BuildMI(BB, X86::FLDCW16m, 4), CWFrameIdx);
}
void X86DAGToDAGISel::EmitFunctionEntryCode(Function &Fn, MachineFunction &MF) {
// If this is main, emit special code for main.
MachineBasicBlock *BB = MF.begin();
if (Fn.hasExternalLinkage() && Fn.getName() == "main")
EmitSpecialCodeForMain(BB, MF.getFrameInfo());
}
/// MatchAddress - Add the specified node to the specified addressing mode,
/// returning true if it cannot be done. This just pattern matches for the
/// addressing mode
bool X86DAGToDAGISel::MatchAddress(SDOperand N, X86ISelAddressMode &AM,
bool isRoot) {
// RIP relative addressing: %rip + 32-bit displacement!
if (AM.isRIPRel) {
if (!AM.ES && AM.JT != -1 && N.getOpcode() == ISD::Constant) {
int64_t Val = cast<ConstantSDNode>(N)->getSignExtended();
if (isInt32(AM.Disp + Val)) {
AM.Disp += Val;
return false;
}
}
return true;
}
int id = N.Val->getNodeId();
bool Available = isSelected(id);
switch (N.getOpcode()) {
default: break;
case ISD::Constant: {
int64_t Val = cast<ConstantSDNode>(N)->getSignExtended();
if (isInt32(AM.Disp + Val)) {
AM.Disp += Val;
return false;
}
break;
}
case X86ISD::Wrapper:
// If value is available in a register both base and index components have
// been picked, we can't fit the result available in the register in the
// addressing mode. Duplicate GlobalAddress or ConstantPool as displacement.
// Can't fit GV or CP in addressing mode for X86-64 medium or large code
// model since the displacement field is 32-bit. Ok for small code model.
// For X86-64 PIC code, only allow GV / CP + displacement so we can use RIP
// relative addressing mode.
if ((!Subtarget->is64Bit() || TM.getCodeModel() == CodeModel::Small) &&
(!Available || (AM.Base.Reg.Val && AM.IndexReg.Val))) {
bool isRIP = Subtarget->is64Bit();
if (isRIP && (AM.Base.Reg.Val || AM.Scale > 1 || AM.IndexReg.Val ||
AM.BaseType == X86ISelAddressMode::FrameIndexBase))
break;
if (ConstantPoolSDNode *CP =
dyn_cast<ConstantPoolSDNode>(N.getOperand(0))) {
if (AM.CP == 0) {
AM.CP = CP->getConstVal();
AM.Align = CP->getAlignment();
AM.Disp += CP->getOffset();
if (isRIP)
AM.isRIPRel = true;
return false;
}
} else if (GlobalAddressSDNode *G =
dyn_cast<GlobalAddressSDNode>(N.getOperand(0))) {
if (AM.GV == 0) {
AM.GV = G->getGlobal();
AM.Disp += G->getOffset();
if (isRIP)
AM.isRIPRel = true;
return false;
}
} else if (isRoot && isRIP) {
if (ExternalSymbolSDNode *S =
dyn_cast<ExternalSymbolSDNode>(N.getOperand(0))) {
AM.ES = S->getSymbol();
AM.isRIPRel = true;
return false;
} else if (JumpTableSDNode *J =
dyn_cast<JumpTableSDNode>(N.getOperand(0))) {
AM.JT = J->getIndex();
AM.isRIPRel = true;
return false;
}
}
}
break;
case ISD::FrameIndex:
if (AM.BaseType == X86ISelAddressMode::RegBase && AM.Base.Reg.Val == 0) {
AM.BaseType = X86ISelAddressMode::FrameIndexBase;
AM.Base.FrameIndex = cast<FrameIndexSDNode>(N)->getIndex();
return false;
}
break;
case ISD::SHL:
if (!Available && AM.IndexReg.Val == 0 && AM.Scale == 1)
if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(N.Val->getOperand(1))) {
unsigned Val = CN->getValue();
if (Val == 1 || Val == 2 || Val == 3) {
AM.Scale = 1 << Val;
SDOperand ShVal = N.Val->getOperand(0);
// Okay, we know that we have a scale by now. However, if the scaled
// value is an add of something and a constant, we can fold the
// constant into the disp field here.
if (ShVal.Val->getOpcode() == ISD::ADD && ShVal.hasOneUse() &&
isa<ConstantSDNode>(ShVal.Val->getOperand(1))) {
AM.IndexReg = ShVal.Val->getOperand(0);
ConstantSDNode *AddVal =
cast<ConstantSDNode>(ShVal.Val->getOperand(1));
uint64_t Disp = AM.Disp + AddVal->getValue() << Val;
if (isInt32(Disp))
AM.Disp = Disp;
else
AM.IndexReg = ShVal;
} else {
AM.IndexReg = ShVal;
}
return false;
}
}
break;
case ISD::MUL:
// X*[3,5,9] -> X+X*[2,4,8]
if (!Available &&
AM.BaseType == X86ISelAddressMode::RegBase &&
AM.Base.Reg.Val == 0 &&
AM.IndexReg.Val == 0)
if (ConstantSDNode *CN = dyn_cast<ConstantSDNode>(N.Val->getOperand(1)))
if (CN->getValue() == 3 || CN->getValue() == 5 || CN->getValue() == 9) {
AM.Scale = unsigned(CN->getValue())-1;
SDOperand MulVal = N.Val->getOperand(0);
SDOperand Reg;
// Okay, we know that we have a scale by now. However, if the scaled
// value is an add of something and a constant, we can fold the
// constant into the disp field here.
if (MulVal.Val->getOpcode() == ISD::ADD && MulVal.hasOneUse() &&
isa<ConstantSDNode>(MulVal.Val->getOperand(1))) {
Reg = MulVal.Val->getOperand(0);
ConstantSDNode *AddVal =
cast<ConstantSDNode>(MulVal.Val->getOperand(1));
uint64_t Disp = AM.Disp + AddVal->getValue() * CN->getValue();
if (isInt32(Disp))
AM.Disp = Disp;
else
Reg = N.Val->getOperand(0);
} else {
Reg = N.Val->getOperand(0);
}
AM.IndexReg = AM.Base.Reg = Reg;
return false;
}
break;
case ISD::ADD: {
if (!Available) {
X86ISelAddressMode Backup = AM;
if (!MatchAddress(N.Val->getOperand(0), AM, false) &&
!MatchAddress(N.Val->getOperand(1), AM, false))
return false;
AM = Backup;
if (!MatchAddress(N.Val->getOperand(1), AM, false) &&
!MatchAddress(N.Val->getOperand(0), AM, false))
return false;
AM = Backup;
}
break;
}
case ISD::OR: {
if (!Available) {
X86ISelAddressMode Backup = AM;
// Look for (x << c1) | c2 where (c2 < c1)
ConstantSDNode *CN = dyn_cast<ConstantSDNode>(N.Val->getOperand(0));
if (CN && !MatchAddress(N.Val->getOperand(1), AM, false)) {
if (AM.GV == NULL && AM.Disp == 0 && CN->getValue() < AM.Scale) {
AM.Disp = CN->getValue();
return false;
}
}
AM = Backup;
CN = dyn_cast<ConstantSDNode>(N.Val->getOperand(1));
if (CN && !MatchAddress(N.Val->getOperand(0), AM, false)) {
if (AM.GV == NULL && AM.Disp == 0 && CN->getValue() < AM.Scale) {
AM.Disp = CN->getValue();
return false;
}
}
AM = Backup;
}
break;
}
}
// Is the base register already occupied?
if (AM.BaseType != X86ISelAddressMode::RegBase || AM.Base.Reg.Val) {
// If so, check to see if the scale index register is set.
if (AM.IndexReg.Val == 0) {
AM.IndexReg = N;
AM.Scale = 1;
return false;
}
// Otherwise, we cannot select it.
return true;
}
// Default, generate it as a register.
AM.BaseType = X86ISelAddressMode::RegBase;
AM.Base.Reg = N;
return false;
}
/// SelectAddr - returns true if it is able pattern match an addressing mode.
/// It returns the operands which make up the maximal addressing mode it can
/// match by reference.
bool X86DAGToDAGISel::SelectAddr(SDOperand N, SDOperand &Base, SDOperand &Scale,
SDOperand &Index, SDOperand &Disp) {
X86ISelAddressMode AM;
if (MatchAddress(N, AM))
return false;
MVT::ValueType VT = N.getValueType();
if (AM.BaseType == X86ISelAddressMode::RegBase) {
if (!AM.Base.Reg.Val)
AM.Base.Reg = CurDAG->getRegister(0, VT);
}
if (!AM.IndexReg.Val)
AM.IndexReg = CurDAG->getRegister(0, VT);
getAddressOperands(AM, Base, Scale, Index, Disp);
return true;
}
/// isZeroNode - Returns true if Elt is a constant zero or a floating point
/// constant +0.0.
static inline bool isZeroNode(SDOperand Elt) {
return ((isa<ConstantSDNode>(Elt) &&
cast<ConstantSDNode>(Elt)->getValue() == 0) ||
(isa<ConstantFPSDNode>(Elt) &&
cast<ConstantFPSDNode>(Elt)->isExactlyValue(0.0)));
}
/// SelectScalarSSELoad - Match a scalar SSE load. In particular, we want to
/// match a load whose top elements are either undef or zeros. The load flavor
/// is derived from the type of N, which is either v4f32 or v2f64.
bool X86DAGToDAGISel::SelectScalarSSELoad(SDOperand Root, SDOperand Pred,
SDOperand N, SDOperand &Base,
SDOperand &Scale, SDOperand &Index,
SDOperand &Disp, SDOperand &InChain,
SDOperand &OutChain) {
if (N.getOpcode() == ISD::SCALAR_TO_VECTOR) {
InChain = N.getOperand(0).getValue(1);
if (ISD::isNON_EXTLoad(InChain.Val) &&
InChain.getValue(0).hasOneUse() &&
CanBeFoldedBy(N.Val, Pred.Val, Root.Val)) {
LoadSDNode *LD = cast<LoadSDNode>(InChain);
if (!SelectAddr(LD->getBasePtr(), Base, Scale, Index, Disp))
return false;
OutChain = LD->getChain();
return true;
}
}
// Also handle the case where we explicitly require zeros in the top
// elements. This is a vector shuffle from the zero vector.
if (N.getOpcode() == ISD::VECTOR_SHUFFLE && N.Val->hasOneUse() &&
N.getOperand(0).getOpcode() == ISD::BUILD_VECTOR &&
N.getOperand(1).getOpcode() == ISD::SCALAR_TO_VECTOR &&
N.getOperand(1).Val->hasOneUse() &&
ISD::isNON_EXTLoad(N.getOperand(1).getOperand(0).Val) &&
N.getOperand(1).getOperand(0).hasOneUse()) {
// Check to see if the BUILD_VECTOR is building a zero vector.
SDOperand BV = N.getOperand(0);
for (unsigned i = 0, e = BV.getNumOperands(); i != e; ++i)
if (!isZeroNode(BV.getOperand(i)) &&
BV.getOperand(i).getOpcode() != ISD::UNDEF)
return false; // Not a zero/undef vector.
// Check to see if the shuffle mask is 4/L/L/L or 2/L, where L is something
// from the LHS.
unsigned VecWidth = BV.getNumOperands();
SDOperand ShufMask = N.getOperand(2);
assert(ShufMask.getOpcode() == ISD::BUILD_VECTOR && "Invalid shuf mask!");
if (ConstantSDNode *C = dyn_cast<ConstantSDNode>(ShufMask.getOperand(0))) {
if (C->getValue() == VecWidth) {
for (unsigned i = 1; i != VecWidth; ++i) {
if (ShufMask.getOperand(i).getOpcode() == ISD::UNDEF) {
// ok.
} else {
ConstantSDNode *C = cast<ConstantSDNode>(ShufMask.getOperand(i));
if (C->getValue() >= VecWidth) return false;
}
}
}
// Okay, this is a zero extending load. Fold it.
LoadSDNode *LD = cast<LoadSDNode>(N.getOperand(1).getOperand(0));
if (!SelectAddr(LD->getBasePtr(), Base, Scale, Index, Disp))
return false;
OutChain = LD->getChain();
InChain = SDOperand(LD, 1);
return true;
}
}
return false;
}
/// SelectLEAAddr - it calls SelectAddr and determines if the maximal addressing
/// mode it matches can be cost effectively emitted as an LEA instruction.
bool X86DAGToDAGISel::SelectLEAAddr(SDOperand N, SDOperand &Base,
SDOperand &Scale,
SDOperand &Index, SDOperand &Disp) {
X86ISelAddressMode AM;
if (MatchAddress(N, AM))
return false;
MVT::ValueType VT = N.getValueType();
unsigned Complexity = 0;
if (AM.BaseType == X86ISelAddressMode::RegBase)
if (AM.Base.Reg.Val)
Complexity = 1;
else
AM.Base.Reg = CurDAG->getRegister(0, VT);
else if (AM.BaseType == X86ISelAddressMode::FrameIndexBase)
Complexity = 4;
if (AM.IndexReg.Val)
Complexity++;
else
AM.IndexReg = CurDAG->getRegister(0, VT);
if (AM.Scale > 2)
Complexity += 2;
// Don't match just leal(,%reg,2). It's cheaper to do addl %reg, %reg
else if (AM.Scale > 1)
Complexity++;
// FIXME: We are artificially lowering the criteria to turn ADD %reg, $GA
// to a LEA. This is determined with some expermentation but is by no means
// optimal (especially for code size consideration). LEA is nice because of
// its three-address nature. Tweak the cost function again when we can run
// convertToThreeAddress() at register allocation time.
if (AM.GV || AM.CP || AM.ES || AM.JT != -1) {
// For X86-64, we should always use lea to materialize RIP relative
// addresses.
if (Subtarget->is64Bit())
Complexity = 4;
else
Complexity += 2;
}
if (AM.Disp && (AM.Base.Reg.Val || AM.IndexReg.Val))
Complexity++;
if (Complexity > 2) {
getAddressOperands(AM, Base, Scale, Index, Disp);
return true;
}
return false;
}
bool X86DAGToDAGISel::TryFoldLoad(SDOperand P, SDOperand N,
SDOperand &Base, SDOperand &Scale,
SDOperand &Index, SDOperand &Disp) {
if (ISD::isNON_EXTLoad(N.Val) &&
N.hasOneUse() &&
CanBeFoldedBy(N.Val, P.Val, P.Val))
return SelectAddr(N.getOperand(1), Base, Scale, Index, Disp);
return false;
}
static bool isRegister0(SDOperand Op) {
if (RegisterSDNode *R = dyn_cast<RegisterSDNode>(Op))
return (R->getReg() == 0);
return false;
}
/// getGlobalBaseReg - Output the instructions required to put the
/// base address to use for accessing globals into a register.
///
SDNode *X86DAGToDAGISel::getGlobalBaseReg() {
assert(!Subtarget->is64Bit() && "X86-64 PIC uses RIP relative addressing");
if (!GlobalBaseReg) {
// Insert the set of GlobalBaseReg into the first MBB of the function
MachineBasicBlock &FirstMBB = BB->getParent()->front();
MachineBasicBlock::iterator MBBI = FirstMBB.begin();
SSARegMap *RegMap = BB->getParent()->getSSARegMap();
// FIXME: when we get to LP64, we will need to create the appropriate
// type of register here.
GlobalBaseReg = RegMap->createVirtualRegister(X86::GR32RegisterClass);
BuildMI(FirstMBB, MBBI, X86::MovePCtoStack, 0);
BuildMI(FirstMBB, MBBI, X86::POP32r, 1, GlobalBaseReg);
}
return CurDAG->getRegister(GlobalBaseReg, TLI.getPointerTy()).Val;
}
static SDNode *FindCallStartFromCall(SDNode *Node) {
if (Node->getOpcode() == ISD::CALLSEQ_START) return Node;
assert(Node->getOperand(0).getValueType() == MVT::Other &&
"Node doesn't have a token chain argument!");
return FindCallStartFromCall(Node->getOperand(0).Val);
}
SDNode *X86DAGToDAGISel::Select(SDOperand N) {
SDNode *Node = N.Val;
MVT::ValueType NVT = Node->getValueType(0);
unsigned Opc, MOpc;
unsigned Opcode = Node->getOpcode();
#ifndef NDEBUG
DEBUG(std::cerr << std::string(Indent, ' '));
DEBUG(std::cerr << "Selecting: ");
DEBUG(Node->dump(CurDAG));
DEBUG(std::cerr << "\n");
Indent += 2;
#endif
if (Opcode >= ISD::BUILTIN_OP_END && Opcode < X86ISD::FIRST_NUMBER) {
#ifndef NDEBUG
DEBUG(std::cerr << std::string(Indent-2, ' '));
DEBUG(std::cerr << "== ");
DEBUG(Node->dump(CurDAG));
DEBUG(std::cerr << "\n");
Indent -= 2;
#endif
return NULL; // Already selected.
}
switch (Opcode) {
default: break;
case X86ISD::GlobalBaseReg:
return getGlobalBaseReg();
case ISD::ADD: {
// Turn ADD X, c to MOV32ri X+c. This cannot be done with tblgen'd
// code and is matched first so to prevent it from being turned into
// LEA32r X+c.
// In 64-bit mode, use LEA to take advantage of RIP-relative addressing.
MVT::ValueType PtrVT = TLI.getPointerTy();
SDOperand N0 = N.getOperand(0);
SDOperand N1 = N.getOperand(1);
if (N.Val->getValueType(0) == PtrVT &&
N0.getOpcode() == X86ISD::Wrapper &&
N1.getOpcode() == ISD::Constant) {
unsigned Offset = (unsigned)cast<ConstantSDNode>(N1)->getValue();
SDOperand C(0, 0);
// TODO: handle ExternalSymbolSDNode.
if (GlobalAddressSDNode *G =
dyn_cast<GlobalAddressSDNode>(N0.getOperand(0))) {
C = CurDAG->getTargetGlobalAddress(G->getGlobal(), PtrVT,
G->getOffset() + Offset);
} else if (ConstantPoolSDNode *CP =
dyn_cast<ConstantPoolSDNode>(N0.getOperand(0))) {
C = CurDAG->getTargetConstantPool(CP->getConstVal(), PtrVT,
CP->getAlignment(),
CP->getOffset()+Offset);
}
if (C.Val) {
if (Subtarget->is64Bit()) {
SDOperand Ops[] = { CurDAG->getRegister(0, PtrVT), getI8Imm(1),
CurDAG->getRegister(0, PtrVT), C };
return CurDAG->SelectNodeTo(N.Val, X86::LEA64r, MVT::i64, Ops, 4);
} else
return CurDAG->SelectNodeTo(N.Val, X86::MOV32ri, PtrVT, C);
}
}
// Other cases are handled by auto-generated code.
break;
}
case ISD::MULHU:
case ISD::MULHS: {
if (Opcode == ISD::MULHU)
switch (NVT) {
default: assert(0 && "Unsupported VT!");
case MVT::i8: Opc = X86::MUL8r; MOpc = X86::MUL8m; break;
case MVT::i16: Opc = X86::MUL16r; MOpc = X86::MUL16m; break;
case MVT::i32: Opc = X86::MUL32r; MOpc = X86::MUL32m; break;
case MVT::i64: Opc = X86::MUL64r; MOpc = X86::MUL64m; break;
}
else
switch (NVT) {
default: assert(0 && "Unsupported VT!");
case MVT::i8: Opc = X86::IMUL8r; MOpc = X86::IMUL8m; break;
case MVT::i16: Opc = X86::IMUL16r; MOpc = X86::IMUL16m; break;
case MVT::i32: Opc = X86::IMUL32r; MOpc = X86::IMUL32m; break;
case MVT::i64: Opc = X86::IMUL64r; MOpc = X86::IMUL64m; break;
}
unsigned LoReg, HiReg;
switch (NVT) {
default: assert(0 && "Unsupported VT!");
case MVT::i8: LoReg = X86::AL; HiReg = X86::AH; break;
case MVT::i16: LoReg = X86::AX; HiReg = X86::DX; break;
case MVT::i32: LoReg = X86::EAX; HiReg = X86::EDX; break;
case MVT::i64: LoReg = X86::RAX; HiReg = X86::RDX; break;
}
SDOperand N0 = Node->getOperand(0);
SDOperand N1 = Node->getOperand(1);
bool foldedLoad = false;
SDOperand Tmp0, Tmp1, Tmp2, Tmp3;
foldedLoad = TryFoldLoad(N, N1, Tmp0, Tmp1, Tmp2, Tmp3);
// MULHU and MULHS are commmutative
if (!foldedLoad) {
foldedLoad = TryFoldLoad(N, N0, Tmp0, Tmp1, Tmp2, Tmp3);
if (foldedLoad) {
N0 = Node->getOperand(1);
N1 = Node->getOperand(0);
}
}
SDOperand Chain;
if (foldedLoad) {
Chain = N1.getOperand(0);
AddToISelQueue(Chain);
} else
Chain = CurDAG->getEntryNode();
SDOperand InFlag(0, 0);
AddToISelQueue(N0);
Chain = CurDAG->getCopyToReg(Chain, CurDAG->getRegister(LoReg, NVT),
N0, InFlag);
InFlag = Chain.getValue(1);
if (foldedLoad) {
AddToISelQueue(Tmp0);
AddToISelQueue(Tmp1);
AddToISelQueue(Tmp2);
AddToISelQueue(Tmp3);
SDOperand Ops[] = { Tmp0, Tmp1, Tmp2, Tmp3, Chain, InFlag };
SDNode *CNode =
CurDAG->getTargetNode(MOpc, MVT::Other, MVT::Flag, Ops, 6);
Chain = SDOperand(CNode, 0);
InFlag = SDOperand(CNode, 1);
} else {
AddToISelQueue(N1);
InFlag =
SDOperand(CurDAG->getTargetNode(Opc, MVT::Flag, N1, InFlag), 0);
}
SDOperand Result = CurDAG->getCopyFromReg(Chain, HiReg, NVT, InFlag);
ReplaceUses(N.getValue(0), Result);
if (foldedLoad)
ReplaceUses(N1.getValue(1), Result.getValue(1));
#ifndef NDEBUG
DEBUG(std::cerr << std::string(Indent-2, ' '));
DEBUG(std::cerr << "=> ");
DEBUG(Result.Val->dump(CurDAG));
DEBUG(std::cerr << "\n");
Indent -= 2;
#endif
return NULL;
}
case ISD::SDIV:
case ISD::UDIV:
case ISD::SREM:
case ISD::UREM: {
bool isSigned = Opcode == ISD::SDIV || Opcode == ISD::SREM;
bool isDiv = Opcode == ISD::SDIV || Opcode == ISD::UDIV;
if (!isSigned)
switch (NVT) {
default: assert(0 && "Unsupported VT!");
case MVT::i8: Opc = X86::DIV8r; MOpc = X86::DIV8m; break;
case MVT::i16: Opc = X86::DIV16r; MOpc = X86::DIV16m; break;
case MVT::i32: Opc = X86::DIV32r; MOpc = X86::DIV32m; break;
case MVT::i64: Opc = X86::DIV64r; MOpc = X86::DIV64m; break;
}
else
switch (NVT) {
default: assert(0 && "Unsupported VT!");
case MVT::i8: Opc = X86::IDIV8r; MOpc = X86::IDIV8m; break;
case MVT::i16: Opc = X86::IDIV16r; MOpc = X86::IDIV16m; break;
case MVT::i32: Opc = X86::IDIV32r; MOpc = X86::IDIV32m; break;
case MVT::i64: Opc = X86::IDIV64r; MOpc = X86::IDIV64m; break;
}
unsigned LoReg, HiReg;
unsigned ClrOpcode, SExtOpcode;
switch (NVT) {
default: assert(0 && "Unsupported VT!");
case MVT::i8:
LoReg = X86::AL; HiReg = X86::AH;
ClrOpcode = X86::MOV8r0;
SExtOpcode = X86::CBW;
break;
case MVT::i16:
LoReg = X86::AX; HiReg = X86::DX;
ClrOpcode = X86::MOV16r0;
SExtOpcode = X86::CWD;
break;
case MVT::i32:
LoReg = X86::EAX; HiReg = X86::EDX;
ClrOpcode = X86::MOV32r0;
SExtOpcode = X86::CDQ;
break;
case MVT::i64:
LoReg = X86::RAX; HiReg = X86::RDX;
ClrOpcode = X86::MOV64r0;
SExtOpcode = X86::CQO;
break;
}
SDOperand N0 = Node->getOperand(0);
SDOperand N1 = Node->getOperand(1);
bool foldedLoad = false;
SDOperand Tmp0, Tmp1, Tmp2, Tmp3;
foldedLoad = TryFoldLoad(N, N1, Tmp0, Tmp1, Tmp2, Tmp3);
SDOperand Chain;
if (foldedLoad) {
Chain = N1.getOperand(0);
AddToISelQueue(Chain);
} else
Chain = CurDAG->getEntryNode();
SDOperand InFlag(0, 0);
AddToISelQueue(N0);
Chain = CurDAG->getCopyToReg(Chain, CurDAG->getRegister(LoReg, NVT),
N0, InFlag);
InFlag = Chain.getValue(1);
if (isSigned) {
// Sign extend the low part into the high part.
InFlag =
SDOperand(CurDAG->getTargetNode(SExtOpcode, MVT::Flag, InFlag), 0);
} else {
// Zero out the high part, effectively zero extending the input.
SDOperand ClrNode = SDOperand(CurDAG->getTargetNode(ClrOpcode, NVT), 0);
Chain = CurDAG->getCopyToReg(Chain, CurDAG->getRegister(HiReg, NVT),
ClrNode, InFlag);
InFlag = Chain.getValue(1);
}
if (foldedLoad) {
AddToISelQueue(Tmp0);
AddToISelQueue(Tmp1);
AddToISelQueue(Tmp2);
AddToISelQueue(Tmp3);
SDOperand Ops[] = { Tmp0, Tmp1, Tmp2, Tmp3, Chain, InFlag };
SDNode *CNode =
CurDAG->getTargetNode(MOpc, MVT::Other, MVT::Flag, Ops, 6);
Chain = SDOperand(CNode, 0);
InFlag = SDOperand(CNode, 1);
} else {
AddToISelQueue(N1);
InFlag =
SDOperand(CurDAG->getTargetNode(Opc, MVT::Flag, N1, InFlag), 0);
}
SDOperand Result = CurDAG->getCopyFromReg(Chain, isDiv ? LoReg : HiReg,
NVT, InFlag);
ReplaceUses(N.getValue(0), Result);
if (foldedLoad)
ReplaceUses(N1.getValue(1), Result.getValue(1));
#ifndef NDEBUG
DEBUG(std::cerr << std::string(Indent-2, ' '));
DEBUG(std::cerr << "=> ");
DEBUG(Result.Val->dump(CurDAG));
DEBUG(std::cerr << "\n");
Indent -= 2;
#endif
return NULL;
}
case ISD::TRUNCATE: {
if (!Subtarget->is64Bit() && NVT == MVT::i8) {
unsigned Opc2;
MVT::ValueType VT;
switch (Node->getOperand(0).getValueType()) {
default: assert(0 && "Unknown truncate!");
case MVT::i16:
Opc = X86::MOV16to16_;
VT = MVT::i16;
Opc2 = X86::TRUNC_16_to8;
break;
case MVT::i32:
Opc = X86::MOV32to32_;
VT = MVT::i32;
Opc2 = X86::TRUNC_32_to8;
break;
}
AddToISelQueue(Node->getOperand(0));
SDOperand Tmp =
SDOperand(CurDAG->getTargetNode(Opc, VT, Node->getOperand(0)), 0);
SDNode *ResNode = CurDAG->getTargetNode(Opc2, NVT, Tmp);
#ifndef NDEBUG
DEBUG(std::cerr << std::string(Indent-2, ' '));
DEBUG(std::cerr << "=> ");
DEBUG(ResNode->dump(CurDAG));
DEBUG(std::cerr << "\n");
Indent -= 2;
#endif
return ResNode;
}
break;
}
}
SDNode *ResNode = SelectCode(N);
#ifndef NDEBUG
DEBUG(std::cerr << std::string(Indent-2, ' '));
DEBUG(std::cerr << "=> ");
if (ResNode == NULL || ResNode == N.Val)
DEBUG(N.Val->dump(CurDAG));
else
DEBUG(ResNode->dump(CurDAG));
DEBUG(std::cerr << "\n");
Indent -= 2;
#endif
return ResNode;
}
bool X86DAGToDAGISel::
SelectInlineAsmMemoryOperand(const SDOperand &Op, char ConstraintCode,
std::vector<SDOperand> &OutOps, SelectionDAG &DAG){
SDOperand Op0, Op1, Op2, Op3;
switch (ConstraintCode) {
case 'o': // offsetable ??
case 'v': // not offsetable ??
default: return true;
case 'm': // memory
if (!SelectAddr(Op, Op0, Op1, Op2, Op3))
return true;
break;
}
OutOps.push_back(Op0);
OutOps.push_back(Op1);
OutOps.push_back(Op2);
OutOps.push_back(Op3);
AddToISelQueue(Op0);
AddToISelQueue(Op1);
AddToISelQueue(Op2);
AddToISelQueue(Op3);
return false;
}
/// createX86ISelDag - This pass converts a legalized DAG into a
/// X86-specific DAG, ready for instruction scheduling.
///
FunctionPass *llvm::createX86ISelDag(X86TargetMachine &TM, bool Fast) {
return new X86DAGToDAGISel(TM, Fast);
}
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