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Fix perf regression: limit debug info to relevant subprograms (#8174) #8177

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Fix perf regression: limit debug info to relevant subprograms (#8174) #8177

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70 changes: 41 additions & 29 deletions lib/Transforms/Scalar/ScalarReplAggregatesHLSL.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -6505,47 +6505,49 @@ ModulePass *llvm::createSROA_Parameter_HLSL() {
namespace {

struct GVDebugInfoPatchCache {
DenseMap<Function *, SetVector<DISubprogram *>> SubprogramsForFunction;
DenseSet<DILocation *> Seen;
DenseMap<DILocation *, DISubprogram *> LocToSubprogram;
DenseMap<Function *, DISubprogram *> FuncToSubprogram;
DITypeIdentifierMap EmptyMap;

DISubprogram *GetSubprogramForLoc(DILocation *Loc) {
auto It = LocToSubprogram.find(Loc);
if (It != LocToSubprogram.end())
return It->second;
DISubprogram *Result = nullptr;
auto *Scope = dyn_cast<DIScope>(Loc->getScope());
while (Scope) {
if (auto SubP = dyn_cast<DISubprogram>(Scope)) {
Result = SubP;
break;
}
Scope = Scope->getScope().resolve(EmptyMap);
}
LocToSubprogram[Loc] = Result;
return Result;
}

// Collect DISubprograms from a DILocation's inlined-at chain.
void CollectSubprograms(DILocation *Loc, SetVector<DISubprogram *> &Set) {
while (Loc) {
// This is potentially very expensive. Avoid repeatedly looking for
// DISubprogram's
if (Seen.count(Loc))
return;
Seen.insert(Loc);
auto *Scope = dyn_cast<DIScope>(Loc->getScope());
while (Scope) {
if (auto SubP = dyn_cast<DISubprogram>(Scope)) {
Set.insert(SubP);
break;
}
Scope = Scope->getScope().resolve(EmptyMap);
}
if (DISubprogram *SP = GetSubprogramForLoc(Loc))
Set.insert(SP);
Loc = Loc->getInlinedAt();
}
}

SetVector<DISubprogram *> &
GetSubprogramsForFunction(Function *F, DebugInfoFinder &DbgFinder) {
auto It = SubprogramsForFunction.find(F);
if (It != SubprogramsForFunction.end())
DISubprogram *GetFuncSubprogram(Function *F, DebugInfoFinder &DbgFinder) {
auto It = FuncToSubprogram.find(F);
if (It != FuncToSubprogram.end())
return It->second;

SetVector<DISubprogram *> &Ret = SubprogramsForFunction[F];
DISubprogram *Result = nullptr;
for (DISubprogram *SP : DbgFinder.subprograms()) {
if (SP->getFunction() == F) {
Ret.insert(SP);
Result = SP;
break;
}
}

for (BasicBlock &BB : *F)
for (Instruction &I : BB)
CollectSubprograms(I.getDebugLoc(), Ret);
return Ret;
FuncToSubprogram[F] = Result;
return Result;
}
};

Expand Down Expand Up @@ -6771,8 +6773,18 @@ static void PatchDebugInfo(GVDebugInfoPatchCache &Cache,

DIBuilder DIB(*GV->getParent());

SetVector<DISubprogram *> &Subprograms =
Cache.GetSubprogramsForFunction(F, DbgFinder);
// Only collect subprograms relevant to this GV to avoid creating
// O(subprograms × globals) debug instructions.
SetVector<DISubprogram *> Subprograms;

if (DISubprogram *SP = Cache.GetFuncSubprogram(F, DbgFinder))
Subprograms.insert(SP);

for (User *U : AI->users()) {
if (Instruction *I = dyn_cast<Instruction>(U))
Cache.CollectSubprograms(I->getDebugLoc(), Subprograms);
}

for (DISubprogram *Subprogram : Subprograms) {
DIScope *Scope = Subprogram;
DebugLoc Loc = DebugLoc::get(DGV->getLine(), 0, Scope);
Expand Down