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[LocalStackSlotAllocation] Minor simplifications. NFC

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Instead of maintaining a separate valid flag for BaseReg, Use
BaseReg.isValid(). I think this is left over from an older
implementation that maintained a vector of base registers.

The other change is not do a speculative assignment to BaseOffset
that needs to be reverted. Only commit it after we do the check.

Reviewed By: arsenm

Differential Revision: https://reviews.llvm.org/D141153
This commit is contained in:
Craig Topper 2023-01-09 09:45:22 -08:00
parent b37758356a
commit 1153313c33
1 changed files with 8 additions and 10 deletions
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18
llvm/lib/CodeGen/LocalStackSlotAllocation.cpp
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@ -288,7 +288,6 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
// stack frame. If it wants one, re-use a suitable one we've previously
// allocated, or if there isn't one that fits the bill, allocate a new one
// and ask the target to create a defining instruction for it.
bool UsedBaseReg = false;
MachineFrameInfo &MFI = Fn.getFrameInfo();
const TargetRegisterInfo *TRI = Fn.getSubtarget().getRegisterInfo();
@ -386,7 +385,7 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
// instruction itself will be taken into account by the target,
// so we don't have to adjust for it here when reusing a base
// register.
if (UsedBaseReg &&
if (BaseReg.isValid() &&
lookupCandidateBaseReg(BaseReg, BaseOffset, FrameSizeAdjust,
LocalOffset, MI, TRI)) {
LLVM_DEBUG(dbgs() << " Reusing base register " << BaseReg << "\n");
@ -396,8 +395,7 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
// No previously defined register was in range, so create a new one.
int64_t InstrOffset = TRI->getFrameIndexInstrOffset(&MI, idx);
int64_t PrevBaseOffset = BaseOffset;
BaseOffset = FrameSizeAdjust + LocalOffset + InstrOffset;
int64_t CandBaseOffset = FrameSizeAdjust + LocalOffset + InstrOffset;
// We'd like to avoid creating single-use virtual base registers.
// Because the FrameRefs are in sorted order, and we've already
@ -406,12 +404,13 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
// then don't bother creating it.
if (ref + 1 >= e ||
!lookupCandidateBaseReg(
BaseReg, BaseOffset, FrameSizeAdjust,
BaseReg, CandBaseOffset, FrameSizeAdjust,
FrameReferenceInsns[ref + 1].getLocalOffset(),
*FrameReferenceInsns[ref + 1].getMachineInstr(), TRI)) {
BaseOffset = PrevBaseOffset;
*FrameReferenceInsns[ref + 1].getMachineInstr(), TRI))
continue;
}
// Save the base offset.
BaseOffset = CandBaseOffset;
// Tell the target to insert the instruction to initialize
// the base register.
@ -428,7 +427,6 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
Offset = -InstrOffset;
++NumBaseRegisters;
UsedBaseReg = true;
}
assert(BaseReg && "Unable to allocate virtual base register!");
@ -440,5 +438,5 @@ bool LocalStackSlotPass::insertFrameReferenceRegisters(MachineFunction &Fn) {
++NumReplacements;
}
return UsedBaseReg;
return BaseReg.isValid();
}