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[Verifier] Fix performance regression for LTO builds

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Summary:
Fix a significant performance regression by introducing GlobalValueVisited field and reusing the map.
This is a follow up to r257823 that slowed down linking Chrome with LTO by 2.5x.

If you revert this commit, please, also revert r257823.

BUG=https://llvm.org/bugs/show_bug.cgi?id=26214

Reviewers: pcc, loladiro, joker.eph

Subscribers: krasin1, joker.eph, loladiro, pcc

Differential Revision: http://reviews.llvm.org/D16338

llvm-svn: 258297
This commit is contained in:
Ivan Krasin 2016-01-20 08:41:22 +00:00
parent 4d1c91fc4d
commit d1b806509e
1 changed files with 7 additions and 6 deletions
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13
lib/IR/Verifier.cpp
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@ -217,6 +217,12 @@ class Verifier : public InstVisitor<Verifier>, VerifierSupport {
/// Cache of constants visited in search of ConstantExprs.
SmallPtrSet<const Constant *, 32> ConstantExprVisited;
// Verify that this GlobalValue is only used in this module.
// This map is used to avoid visiting uses twice. We can arrive at a user
// twice, if they have multiple operands. In particular for very large
// constant expressions, we can arrive at a particular user many times.
SmallPtrSet<const Value *, 32> GlobalValueVisited;
void checkAtomicMemAccessSize(const Module *M, Type *Ty,
const Instruction *I);
public:
@ -494,12 +500,7 @@ void Verifier::visitGlobalValue(const GlobalValue &GV) {
if (GV.isDeclarationForLinker())
Assert(!GV.hasComdat(), "Declaration may not be in a Comdat!", &GV);
// Verify that this GlobalValue is only used in this module.
// This map is used to avoid visiting uses twice. We can arrive at a user
// twice, if they have multiple operands. In particular for very large
// constant expressions, we can arrive at a particular user many times.
SmallPtrSet<const Value *, 32> Visited;
forEachUser(&GV, Visited, [&](const Value *V) -> bool {
forEachUser(&GV, GlobalValueVisited, [&](const Value *V) -> bool {
if (const Instruction *I = dyn_cast<Instruction>(V)) {
if (!I->getParent() || !I->getParent()->getParent())
CheckFailed("Global is referenced by parentless instruction!", &GV,