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[CFIInstrInserter] Use number of supported registers (NFC) (#71797)

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This makes use of the more accurate register number introduced in PR
#70222 to avoid CFI calculations for unsupported registers.

This has basically no impact right now, but results in a 0.2% compile-time
improvement at O0 when applied on top of #70958.

The reason is that the extra registers that PR adds push the `BitVector`
out of the `SmallVector` space, which results in an outsized impact.
(This does make me wonder whether `BitVector` should accept an `N`
template parameter to allow using a larger `SmallVector`...)
This commit is contained in:
Nikita Popov
2023-11-09 14:43:45 +01:00
committed by GitHub
parent b90cba10f9
commit f67158422c
1 changed files with 2 additions and 2 deletions
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4
llvm/lib/CodeGen/CFIInstrInserter.cpp
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@@ -151,7 +151,7 @@ void CFIInstrInserter::calculateCFAInfo(MachineFunction &MF) {
Register InitialRegister =
MF.getSubtarget().getFrameLowering()->getInitialCFARegister(MF);
InitialRegister = TRI.getDwarfRegNum(InitialRegister, true);
unsigned NumRegs = TRI.getNumRegs();
unsigned NumRegs = TRI.getNumSupportedRegs(MF);
// Initialize MBBMap.
for (MachineBasicBlock &MBB : MF) {
@@ -181,7 +181,7 @@ void CFIInstrInserter::calculateOutgoingCFAInfo(MBBCFAInfo &MBBInfo) {
MachineFunction *MF = MBBInfo.MBB->getParent();
const std::vector<MCCFIInstruction> &Instrs = MF->getFrameInstructions();
const TargetRegisterInfo &TRI = *MF->getSubtarget().getRegisterInfo();
unsigned NumRegs = TRI.getNumRegs();
unsigned NumRegs = TRI.getNumSupportedRegs(*MF);
BitVector CSRSaved(NumRegs), CSRRestored(NumRegs);
// Determine cfa offset and register set by the block.