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[RISCV] Use DenseMap to track V0 definition. NFC #84465

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Merged
merged 3 commits into from
Mar 21, 2024
Merged

[RISCV] Use DenseMap to track V0 definition. NFC #84465

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[RISCV] Use DenseMap to track V0 definition. NFC
lukel97 Mar 7, 2024
cf7bc7a
Use readsRegister
lukel97 Mar 11, 2024
1eb1f13
clang-format
lukel97 Mar 11, 2024
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48 changes: 27 additions & 21 deletions llvm/lib/Target/RISCV/RISCVFoldMasks.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -47,10 +47,13 @@ class RISCVFoldMasks : public MachineFunctionPass {
StringRef getPassName() const override { return "RISC-V Fold Masks"; }

private:
bool convertToUnmasked(MachineInstr &MI, MachineInstr *MaskDef) const;
bool convertVMergeToVMv(MachineInstr &MI, MachineInstr *MaskDef) const;
bool convertToUnmasked(MachineInstr &MI) const;
bool convertVMergeToVMv(MachineInstr &MI) const;

bool isAllOnesMask(MachineInstr *MaskDef) const;
bool isAllOnesMask(const MachineInstr *MaskDef) const;

/// Maps uses of V0 to the corresponding def of V0.
DenseMap<const MachineInstr *, const MachineInstr *> V0Defs;
};

} // namespace
Expand All @@ -59,10 +62,9 @@ char RISCVFoldMasks::ID = 0;

INITIALIZE_PASS(RISCVFoldMasks, DEBUG_TYPE, "RISC-V Fold Masks", false, false)

bool RISCVFoldMasks::isAllOnesMask(MachineInstr *MaskDef) const {
if (!MaskDef)
return false;
assert(MaskDef->isCopy() && MaskDef->getOperand(0).getReg() == RISCV::V0);
bool RISCVFoldMasks::isAllOnesMask(const MachineInstr *MaskDef) const {
assert(MaskDef && MaskDef->isCopy() &&
MaskDef->getOperand(0).getReg() == RISCV::V0);
Register SrcReg = TRI->lookThruCopyLike(MaskDef->getOperand(1).getReg(), MRI);
if (!SrcReg.isVirtual())
return false;
Expand All @@ -89,8 +91,7 @@ bool RISCVFoldMasks::isAllOnesMask(MachineInstr *MaskDef) const {

// Transform (VMERGE_VVM_<LMUL> false, false, true, allones, vl, sew) to
// (VMV_V_V_<LMUL> false, true, vl, sew). It may decrease uses of VMSET.
bool RISCVFoldMasks::convertVMergeToVMv(MachineInstr &MI,
MachineInstr *V0Def) const {
bool RISCVFoldMasks::convertVMergeToVMv(MachineInstr &MI) const {
#define CASE_VMERGE_TO_VMV(lmul) \
case RISCV::PseudoVMERGE_VVM_##lmul: \
NewOpc = RISCV::PseudoVMV_V_V_##lmul; \
Expand All @@ -116,7 +117,7 @@ bool RISCVFoldMasks::convertVMergeToVMv(MachineInstr &MI,
return false;

assert(MI.getOperand(4).isReg() && MI.getOperand(4).getReg() == RISCV::V0);
if (!isAllOnesMask(V0Def))
if (!isAllOnesMask(V0Defs.lookup(&MI)))
return false;

MI.setDesc(TII->get(NewOpc));
Expand All @@ -133,14 +134,13 @@ bool RISCVFoldMasks::convertVMergeToVMv(MachineInstr &MI,
return true;
}

bool RISCVFoldMasks::convertToUnmasked(MachineInstr &MI,
MachineInstr *MaskDef) const {
bool RISCVFoldMasks::convertToUnmasked(MachineInstr &MI) const {
const RISCV::RISCVMaskedPseudoInfo *I =
RISCV::getMaskedPseudoInfo(MI.getOpcode());
if (!I)
return false;

if (!isAllOnesMask(MaskDef))
if (!isAllOnesMask(V0Defs.lookup(&MI)))
return false;

// There are two classes of pseudos in the table - compares and
Expand Down Expand Up @@ -198,20 +198,26 @@ bool RISCVFoldMasks::runOnMachineFunction(MachineFunction &MF) {
// $v0:vr = COPY %mask:vr
// %x:vr = Pseudo_MASK %a:vr, %b:br, $v0:vr
//
// Because $v0 isn't in SSA, keep track of it so we can check the mask operand
// on each pseudo.
MachineInstr *CurrentV0Def;
for (MachineBasicBlock &MBB : MF) {
CurrentV0Def = nullptr;
for (MachineInstr &MI : MBB) {
Changed |= convertToUnmasked(MI, CurrentV0Def);
Changed |= convertVMergeToVMv(MI, CurrentV0Def);
// Because $v0 isn't in SSA, keep track of its definition at each use so we
// can check mask operands.
for (const MachineBasicBlock &MBB : MF) {
const MachineInstr *CurrentV0Def = nullptr;
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This ignores defs of V0 from outside the BB, since we're only interested in the local

$v0:vr = COPY %mask:vr
%x:vr = Pseudo_MASK %a:vr, %b:br, $v0:vr

format.

for (const MachineInstr &MI : MBB) {
if (MI.readsRegister(RISCV::V0, TRI))
V0Defs[&MI] = CurrentV0Def;

if (MI.definesRegister(RISCV::V0, TRI))
CurrentV0Def = &MI;
}
}

for (MachineBasicBlock &MBB : MF) {
for (MachineInstr &MI : MBB) {
Changed |= convertToUnmasked(MI);
Changed |= convertVMergeToVMv(MI);
}
}

return Changed;
}

Expand Down