[llvm] e4d951d - LowerTypeTests: Fix quadratic complexity.
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Tue Apr 15 16:03:06 PDT 2025
Author: Peter Collingbourne
Date: 2025-04-15T16:03:03-07:00
New Revision: e4d951d2e42a9124bd87275a864804c4b84b62e3
URL: https://github.com/llvm/llvm-project/commit/e4d951d2e42a9124bd87275a864804c4b84b62e3
DIFF: https://github.com/llvm/llvm-project/commit/e4d951d2e42a9124bd87275a864804c4b84b62e3.diff
LOG: LowerTypeTests: Fix quadratic complexity.
Currently we have quadratic complexity in LowerTypeTests because
ScopedSaveAliaseesAndUsed loops over all aliases for each disjoint
set, and the number of aliases and number of disjoint sets is
roughly proportional to the program size. Fix that by moving
ScopedSaveAliaseesAndUsed to LowerTypeTestsModule::lower() so that
we do this only once.
Reviewers: fmayer, vitalybuka
Reviewed By: vitalybuka
Pull Request: https://github.com/llvm/llvm-project/pull/135875
Added:
Modified:
llvm/lib/Transforms/IPO/LowerTypeTests.cpp
Removed:
################################################################################
diff --git a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
index 7cf7d74acfcfa..8e9f24dfc31fa 100644
--- a/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
+++ b/llvm/lib/Transforms/IPO/LowerTypeTests.cpp
@@ -1669,61 +1669,55 @@ void LowerTypeTestsModule::buildBitSetsFromFunctionsNative(
lowerTypeTestCalls(TypeIds, JumpTable, GlobalLayout);
- {
- ScopedSaveAliaseesAndUsed S(M);
+ // Build aliases pointing to offsets into the jump table, and replace
+ // references to the original functions with references to the aliases.
+ for (unsigned I = 0; I != Functions.size(); ++I) {
+ Function *F = cast<Function>(Functions[I]->getGlobal());
+ bool IsJumpTableCanonical = Functions[I]->isJumpTableCanonical();
- // Build aliases pointing to offsets into the jump table, and replace
- // references to the original functions with references to the aliases.
- for (unsigned I = 0; I != Functions.size(); ++I) {
- Function *F = cast<Function>(Functions[I]->getGlobal());
- bool IsJumpTableCanonical = Functions[I]->isJumpTableCanonical();
-
- Constant *CombinedGlobalElemPtr = ConstantExpr::getInBoundsGetElementPtr(
- JumpTableType, JumpTable,
- ArrayRef<Constant *>{ConstantInt::get(IntPtrTy, 0),
- ConstantInt::get(IntPtrTy, I)});
-
- const bool IsExported = Functions[I]->isExported();
- if (!IsJumpTableCanonical) {
- GlobalValue::LinkageTypes LT = IsExported
- ? GlobalValue::ExternalLinkage
- : GlobalValue::InternalLinkage;
- GlobalAlias *JtAlias = GlobalAlias::create(F->getValueType(), 0, LT,
- F->getName() + ".cfi_jt",
- CombinedGlobalElemPtr, &M);
- if (IsExported)
- JtAlias->setVisibility(GlobalValue::HiddenVisibility);
- else
- appendToUsed(M, {JtAlias});
- }
+ Constant *CombinedGlobalElemPtr = ConstantExpr::getInBoundsGetElementPtr(
+ JumpTableType, JumpTable,
+ ArrayRef<Constant *>{ConstantInt::get(IntPtrTy, 0),
+ ConstantInt::get(IntPtrTy, I)});
+
+ const bool IsExported = Functions[I]->isExported();
+ if (!IsJumpTableCanonical) {
+ GlobalValue::LinkageTypes LT = IsExported ? GlobalValue::ExternalLinkage
+ : GlobalValue::InternalLinkage;
+ GlobalAlias *JtAlias = GlobalAlias::create(F->getValueType(), 0, LT,
+ F->getName() + ".cfi_jt",
+ CombinedGlobalElemPtr, &M);
+ if (IsExported)
+ JtAlias->setVisibility(GlobalValue::HiddenVisibility);
+ else
+ appendToUsed(M, {JtAlias});
+ }
- if (IsExported) {
- if (IsJumpTableCanonical)
- ExportSummary->cfiFunctionDefs().emplace(F->getName());
- else
- ExportSummary->cfiFunctionDecls().emplace(F->getName());
- }
+ if (IsExported) {
+ if (IsJumpTableCanonical)
+ ExportSummary->cfiFunctionDefs().emplace(F->getName());
+ else
+ ExportSummary->cfiFunctionDecls().emplace(F->getName());
+ }
- if (!IsJumpTableCanonical) {
- if (F->hasExternalWeakLinkage())
- replaceWeakDeclarationWithJumpTablePtr(F, CombinedGlobalElemPtr,
- IsJumpTableCanonical);
- else
- replaceCfiUses(F, CombinedGlobalElemPtr, IsJumpTableCanonical);
- } else {
- assert(F->getType()->getAddressSpace() == 0);
-
- GlobalAlias *FAlias =
- GlobalAlias::create(F->getValueType(), 0, F->getLinkage(), "",
- CombinedGlobalElemPtr, &M);
- FAlias->setVisibility(F->getVisibility());
- FAlias->takeName(F);
- if (FAlias->hasName())
- F->setName(FAlias->getName() + ".cfi");
- replaceCfiUses(F, FAlias, IsJumpTableCanonical);
- if (!F->hasLocalLinkage())
- F->setVisibility(GlobalVariable::HiddenVisibility);
- }
+ if (!IsJumpTableCanonical) {
+ if (F->hasExternalWeakLinkage())
+ replaceWeakDeclarationWithJumpTablePtr(F, CombinedGlobalElemPtr,
+ IsJumpTableCanonical);
+ else
+ replaceCfiUses(F, CombinedGlobalElemPtr, IsJumpTableCanonical);
+ } else {
+ assert(F->getType()->getAddressSpace() == 0);
+
+ GlobalAlias *FAlias = GlobalAlias::create(
+ F->getValueType(), 0, F->getLinkage(), "", CombinedGlobalElemPtr, &M);
+ FAlias->setVisibility(F->getVisibility());
+ FAlias->takeName(F);
+ if (FAlias->hasName())
+ F->setName(FAlias->getName() + ".cfi");
+ replaceCfiUses(F, FAlias, IsJumpTableCanonical);
+ if (!F->hasLocalLinkage())
+ F->setVisibility(GlobalVariable::HiddenVisibility);
}
}
@@ -2339,39 +2333,43 @@ bool LowerTypeTestsModule::lower() {
if (GlobalClasses.empty())
return false;
- // For each disjoint set we found...
- for (const auto &C : GlobalClasses) {
- if (!C->isLeader())
- continue;
-
- ++NumTypeIdDisjointSets;
- // Build the list of type identifiers in this disjoint set.
- std::vector<Metadata *> TypeIds;
- std::vector<GlobalTypeMember *> Globals;
- std::vector<ICallBranchFunnel *> ICallBranchFunnels;
- for (auto M : GlobalClasses.members(*C)) {
- if (isa<Metadata *>(M))
- TypeIds.push_back(cast<Metadata *>(M));
- else if (isa<GlobalTypeMember *>(M))
- Globals.push_back(cast<GlobalTypeMember *>(M));
- else
- ICallBranchFunnels.push_back(cast<ICallBranchFunnel *>(M));
- }
-
- // Order type identifiers by unique ID for determinism. This ordering is
- // stable as there is a one-to-one mapping between metadata and unique IDs.
- llvm::sort(TypeIds, [&](Metadata *M1, Metadata *M2) {
- return TypeIdInfo[M1].UniqueId < TypeIdInfo[M2].UniqueId;
- });
+ {
+ ScopedSaveAliaseesAndUsed S(M);
+ // For each disjoint set we found...
+ for (const auto &C : GlobalClasses) {
+ if (!C->isLeader())
+ continue;
- // Same for the branch funnels.
- llvm::sort(ICallBranchFunnels,
- [&](ICallBranchFunnel *F1, ICallBranchFunnel *F2) {
- return F1->UniqueId < F2->UniqueId;
- });
+ ++NumTypeIdDisjointSets;
+ // Build the list of type identifiers in this disjoint set.
+ std::vector<Metadata *> TypeIds;
+ std::vector<GlobalTypeMember *> Globals;
+ std::vector<ICallBranchFunnel *> ICallBranchFunnels;
+ for (auto M : GlobalClasses.members(*C)) {
+ if (isa<Metadata *>(M))
+ TypeIds.push_back(cast<Metadata *>(M));
+ else if (isa<GlobalTypeMember *>(M))
+ Globals.push_back(cast<GlobalTypeMember *>(M));
+ else
+ ICallBranchFunnels.push_back(cast<ICallBranchFunnel *>(M));
+ }
- // Build bitsets for this disjoint set.
- buildBitSetsFromDisjointSet(TypeIds, Globals, ICallBranchFunnels);
+ // Order type identifiers by unique ID for determinism. This ordering is
+ // stable as there is a one-to-one mapping between metadata and unique
+ // IDs.
+ llvm::sort(TypeIds, [&](Metadata *M1, Metadata *M2) {
+ return TypeIdInfo[M1].UniqueId < TypeIdInfo[M2].UniqueId;
+ });
+
+ // Same for the branch funnels.
+ llvm::sort(ICallBranchFunnels,
+ [&](ICallBranchFunnel *F1, ICallBranchFunnel *F2) {
+ return F1->UniqueId < F2->UniqueId;
+ });
+
+ // Build bitsets for this disjoint set.
+ buildBitSetsFromDisjointSet(TypeIds, Globals, ICallBranchFunnels);
+ }
}
allocateByteArrays();
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