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[RISCV][NFC] Simplify the sp-offset reduction by spimm of CM.PUSH/POP. #66667

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Merged
merged 1 commit into from
Sep 19, 2023
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[RISCV][NFC] Simplify the sp-offset reduction by spimm of CM.PUSH/POP. #66667

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23 changes: 6 additions & 17 deletions llvm/lib/Target/RISCV/RISCVFrameLowering.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -276,16 +276,6 @@ static Register getMaxPushPopReg(const MachineFunction &MF,
return MaxPushPopReg;
}

static uint64_t adjSPInPushPop(MachineBasicBlock::iterator MBBI,
unsigned RequiredStack, unsigned FreePushStack,
bool IsPop) {
if (FreePushStack > RequiredStack)
RequiredStack = 0;
unsigned Spimm = std::min(RequiredStack, 48u);
MBBI->getOperand(1).setImm(Spimm);
return alignTo(RequiredStack - Spimm, 16);
}

// Return true if the specified function should have a dedicated frame
// pointer register. This is true if frame pointer elimination is
// disabled, if it needs dynamic stack realignment, if the function has
Expand Down Expand Up @@ -539,10 +529,9 @@ void RISCVFrameLowering::emitPrologue(MachineFunction &MF,
if (RVFI->isPushable(MF) && FirstFrameSetup->getOpcode() == RISCV::CM_PUSH) {
// Use available stack adjustment in push instruction to allocate additional
// stack space.
unsigned PushStack = RVFI->getRVPushRegs() * (STI.getXLen() / 8);
unsigned SpImmBase = RVFI->getRVPushStackSize();
StackSize = adjSPInPushPop(FirstFrameSetup, StackSize,
(SpImmBase - PushStack), true);
uint64_t Spimm = std::min(StackSize, (uint64_t)48);
FirstFrameSetup->getOperand(1).setImm(Spimm);
StackSize -= Spimm;
}

if (StackSize != 0) {
Expand Down Expand Up @@ -777,9 +766,9 @@ void RISCVFrameLowering::emitEpilogue(MachineFunction &MF,
MBBI->getOpcode() == RISCV::CM_POP) {
// Use available stack adjustment in pop instruction to deallocate stack
// space.
unsigned PushStack = RVFI->getRVPushRegs() * (STI.getXLen() / 8);
unsigned SpImmBase = RVFI->getRVPushStackSize();
StackSize = adjSPInPushPop(MBBI, StackSize, (SpImmBase - PushStack), true);
uint64_t Spimm = std::min(StackSize, (uint64_t)48);
MBBI->getOperand(1).setImm(Spimm);
StackSize -= Spimm;
}

// Deallocate stack
Expand Down