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[CodeGen] Use cached version of getRegPressureSetLimit #119194

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[CodeGen] Use cached version of getRegPressureSetLimit #119194

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c9b9fa6
[𝘀𝗽𝗿] initial version
wangpc-pp Dec 9, 2024
b0d87f2
Rewrite uses in AM/PPC targets
wangpc-pp Dec 9, 2024
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4 changes: 3 additions & 1 deletion llvm/lib/CodeGen/MachineLICM.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -123,6 +123,7 @@ namespace {
const TargetRegisterInfo *TRI = nullptr;
const MachineFrameInfo *MFI = nullptr;
MachineRegisterInfo *MRI = nullptr;
RegisterClassInfo RegClassInfo;
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The way RegisterClassInfo is currently used, it gets recomputed for every pass that uses it. It should probably move to be a normal analysis

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I was thinking this, especially as it has some saved state to work out when it needs to recompute. I think that's probably a good follow-up?

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Relatedly, we also do not serialize the set of reserved registers in MIR

TargetSchedModel SchedModel;
bool PreRegAlloc = false;
bool HasProfileData = false;
Expand Down Expand Up @@ -389,6 +390,7 @@ bool MachineLICMImpl::run(MachineFunction &MF) {
MFI = &MF.getFrameInfo();
MRI = &MF.getRegInfo();
SchedModel.init(&ST);
RegClassInfo.runOnMachineFunction(MF);

HasProfileData = MF.getFunction().hasProfileData();

Expand All @@ -405,7 +407,7 @@ bool MachineLICMImpl::run(MachineFunction &MF) {
std::fill(RegPressure.begin(), RegPressure.end(), 0);
RegLimit.resize(NumRPS);
for (unsigned i = 0, e = NumRPS; i != e; ++i)
RegLimit[i] = TRI->getRegPressureSetLimit(MF, i);
RegLimit[i] = RegClassInfo.getRegPressureSetLimit(i);
}

if (HoistConstLoads)
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2 changes: 1 addition & 1 deletion llvm/lib/CodeGen/MachinePipeliner.cpp
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Expand Up @@ -1326,7 +1326,7 @@ class HighRegisterPressureDetector {
// Calculate the upper limit of each pressure set
void computePressureSetLimit(const RegisterClassInfo &RCI) {
for (unsigned PSet = 0; PSet < PSetNum; PSet++)
PressureSetLimit[PSet] = TRI->getRegPressureSetLimit(MF, PSet);
PressureSetLimit[PSet] = RCI.getRegPressureSetLimit(PSet);
}

// There are two patterns of last-use.
Expand Down
2 changes: 1 addition & 1 deletion llvm/lib/CodeGen/MachineSink.cpp
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Expand Up @@ -1094,7 +1094,7 @@ bool MachineSinking::registerPressureSetExceedsLimit(
std::vector<unsigned> BBRegisterPressure = getBBRegisterPressure(MBB);
for (; *PS != -1; PS++)
if (Weight + BBRegisterPressure[*PS] >=
TRI->getRegPressureSetLimit(*MBB.getParent(), *PS))
RegClassInfo.getRegPressureSetLimit(*PS))
return true;
return false;
}
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3 changes: 1 addition & 2 deletions llvm/lib/Target/ARM/ARMBaseInstrInfo.cpp
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Expand Up @@ -6936,7 +6936,6 @@ bool ARMPipelinerLoopInfo::tooMuchRegisterPressure(SwingSchedulerDAG &SSD,
RegClassInfo.runOnMachineFunction(*MF);
RPTracker.init(MF, &RegClassInfo, nullptr, EndLoop->getParent(),
EndLoop->getParent()->end(), false, false);
const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();

bumpCrossIterationPressure(RPTracker, CrossIterationNeeds);

Expand Down Expand Up @@ -6979,7 +6978,7 @@ bool ARMPipelinerLoopInfo::tooMuchRegisterPressure(SwingSchedulerDAG &SSD,

auto &P = RPTracker.getPressure().MaxSetPressure;
for (unsigned I = 0, E = P.size(); I < E; ++I)
if (P[I] > TRI->getRegPressureSetLimit(*MF, I)) {
if (P[I] > RegClassInfo.getRegPressureSetLimit(I)) {
return true;
}
return false;
Expand Down
4 changes: 2 additions & 2 deletions llvm/lib/Target/PowerPC/PPCInstrInfo.cpp
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Expand Up @@ -643,8 +643,8 @@ bool PPCInstrInfo::shouldReduceRegisterPressure(
};

// For now we only care about float and double type fma.
unsigned VSSRCLimit = TRI->getRegPressureSetLimit(
*MBB->getParent(), PPC::RegisterPressureSets::VSSRC);
unsigned VSSRCLimit =
RegClassInfo->getRegPressureSetLimit(PPC::RegisterPressureSets::VSSRC);

// Only reduce register pressure when pressure is high.
return GetMBBPressure(MBB)[PPC::RegisterPressureSets::VSSRC] >
Expand Down
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