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[SystemZ] Fix compile time regression in adjustInliningThreshold(). #137527

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Merged
merged 4 commits into from
Apr 28, 2025
Merged

[SystemZ] Fix compile time regression in adjustInliningThreshold(). #137527

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65bc5bf
IP
JonPsson1 Apr 27, 2025
be26bc9
Updated per review.
JonPsson1 Apr 27, 2025
7e44c55
Use instructions() and avoid goto.
JonPsson1 Apr 28, 2025
079b2d5
GV -> *GV in auto decl for clarity
JonPsson1 Apr 28, 2025
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50 changes: 29 additions & 21 deletions llvm/lib/Target/SystemZ/SystemZTargetTransformInfo.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -80,7 +80,6 @@ unsigned SystemZTTIImpl::adjustInliningThreshold(const CallBase *CB) const {
const Function *Callee = CB->getCalledFunction();
if (!Callee)
return 0;
const Module *M = Caller->getParent();

// Increase the threshold if an incoming argument is used only as a memcpy
// source.
Expand All @@ -92,29 +91,38 @@ unsigned SystemZTTIImpl::adjustInliningThreshold(const CallBase *CB) const {
}
}

// Give bonus for globals used much in both caller and callee.
std::set<const GlobalVariable *> CalleeGlobals;
std::set<const GlobalVariable *> CallerGlobals;
for (const GlobalVariable &Global : M->globals())
for (const User *U : Global.users())
if (const Instruction *User = dyn_cast<Instruction>(U)) {
if (User->getParent()->getParent() == Callee)
CalleeGlobals.insert(&Global);
if (User->getParent()->getParent() == Caller)
CallerGlobals.insert(&Global);
// Give bonus for globals used much in both caller and a relatively small
// callee.
if (Callee->getInstructionCount() < 200) {
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@nikic nikic Apr 27, 2025

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getInstructionCount() is going to iterate over the whole function to determine the instruction count. It's usually better to always do the analysis and just bail out if it inspects too many instructions.

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@JonPsson1 JonPsson1 Apr 28, 2025

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ok, using a counter instead.

std::map<const Value *, unsigned> Ptr2NumUses;
for (auto &BB : *Callee)
for (auto &I : BB) {
if (const auto *SI = dyn_cast<StoreInst>(&I)) {
if (!SI->isVolatile())
Ptr2NumUses[SI->getPointerOperand()]++;
} else if (const auto *LI = dyn_cast<LoadInst>(&I)) {
if (!LI->isVolatile())
Ptr2NumUses[LI->getPointerOperand()]++;
} else if (const auto *GEP = dyn_cast<GetElementPtrInst>(&I)) {
unsigned NumStores = 0, NumLoads = 0;
countNumMemAccesses(GEP, NumStores, NumLoads, Callee);
Ptr2NumUses[GEP->getPointerOperand()] += NumLoads + NumStores;
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@nikic nikic Apr 27, 2025

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It seems like nothing actually cares about loads and stores separately? Make things simpler by having countNumMemAccesses return the total count?

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@JonPsson1 JonPsson1 Apr 27, 2025

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There actually is a bit further down - separate checks for number of loads and stores. It may be that these could be combined there as well, but that should probably wait and be benchmarked after this.

}
}
for (auto *GV : CalleeGlobals)
if (CallerGlobals.count(GV)) {
unsigned CalleeStores = 0, CalleeLoads = 0;
unsigned CallerStores = 0, CallerLoads = 0;
countNumMemAccesses(GV, CalleeStores, CalleeLoads, Callee);
countNumMemAccesses(GV, CallerStores, CallerLoads, Caller);
if ((CalleeStores + CalleeLoads) > 10 &&
(CallerStores + CallerLoads) > 10) {
Bonus = 1000;
break;

for (auto I : Ptr2NumUses) {
const Value *Ptr = I.first;
unsigned NumCalleeUses = I.second;
if (NumCalleeUses > 10 && isa<GlobalVariable>(Ptr)) {
unsigned CallerStores = 0, CallerLoads = 0;
countNumMemAccesses(Ptr, CallerStores, CallerLoads, Caller);
if (CallerStores + CallerLoads > 10) {
Bonus = 1000;
break;
}
}
}
}

// Give bonus when Callee accesses an Alloca of Caller heavily.
unsigned NumStores = 0;
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