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AMDGPU: Don't fold undef uses or copies with implicit uses

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llvm-svn: 283476
This commit is contained in:
Matt Arsenault 2016-10-06 18:12:13 +00:00
parent 9ff673edd1
commit 0c63adb6bd
1 changed files with 22 additions and 4 deletions
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26
lib/Target/AMDGPU/SIFoldOperands.cpp
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@ -92,11 +92,18 @@ FunctionPass *llvm::createSIFoldOperandsPass() {
return new SIFoldOperands();
}
static bool isSafeToFold(unsigned Opcode) {
switch(Opcode) {
static bool isSafeToFold(const MachineInstr &MI) {
switch (MI.getOpcode()) {
case AMDGPU::V_MOV_B32_e32:
case AMDGPU::V_MOV_B32_e64:
case AMDGPU::V_MOV_B64_PSEUDO:
case AMDGPU::V_MOV_B64_PSEUDO: {
// If there are additional implicit register operands, this may be used for
// register indexing so the source register operand isn't simply copied.
unsigned NumOps = MI.getDesc().getNumOperands() +
MI.getDesc().getNumImplicitUses();
return MI.getNumOperands() == NumOps;
}
case AMDGPU::S_MOV_B32:
case AMDGPU::S_MOV_B64:
case AMDGPU::COPY:
@ -203,6 +210,14 @@ static bool tryAddToFoldList(std::vector<FoldCandidate> &FoldList,
return true;
}
// If the use operand doesn't care about the value, this may be an operand only
// used for register indexing, in which case it is unsafe to fold.
static bool isUseSafeToFold(const MachineInstr &MI,
const MachineOperand &UseMO) {
return !UseMO.isUndef();
//return !MI.hasRegisterImplicitUseOperand(UseMO.getReg());
}
static void foldOperand(MachineOperand &OpToFold, MachineInstr *UseMI,
unsigned UseOpIdx,
std::vector<FoldCandidate> &FoldList,
@ -211,6 +226,9 @@ static void foldOperand(MachineOperand &OpToFold, MachineInstr *UseMI,
MachineRegisterInfo &MRI) {
const MachineOperand &UseOp = UseMI->getOperand(UseOpIdx);
if (!isUseSafeToFold(*UseMI, UseOp))
return;
// FIXME: Fold operands with subregs.
if (UseOp.isReg() && OpToFold.isReg()) {
if (UseOp.isImplicit() || UseOp.getSubReg() != AMDGPU::NoSubRegister)
@ -477,7 +495,7 @@ bool SIFoldOperands::runOnMachineFunction(MachineFunction &MF) {
Next = std::next(I);
MachineInstr &MI = *I;
if (!isSafeToFold(MI.getOpcode()))
if (!isSafeToFold(MI))
continue;
unsigned OpSize = TII->getOpSize(MI, 1);