alexfh wrote:
@usx95 may be able to help with the reproducer.
In the meantime, I'm trying to collect some information on the compile times.
So far it looks like we have a ~10-15x compile time regression on some
translation units. Without this patch `-ftime-report` shows:
```
===-------------------------------------------------------------------------===
Clang front-end time report
===-------------------------------------------------------------------------===
Total Execution Time: 39.1940 seconds (39.7238 wall clock)
---User Time--- --System Time-- --User+System-- ---Wall Time--- ---
Name ---
28.2611 ( 77.5%) 1.8439 ( 67.3%) 30.1050 ( 76.8%) 30.5230 ( 76.8%) Clang
front-end timer
8.1911 ( 22.5%) 0.8980 ( 32.7%) 9.0891 ( 23.2%) 9.2009 ( 23.2%)
Reading modules
36.4522 (100.0%) 2.7419 (100.0%) 39.1940 (100.0%) 39.7238 (100.0%) Total
```
With it:
```
===-------------------------------------------------------------------------===
Clang front-end time report
===-------------------------------------------------------------------------===
Total Execution Time: 466.7373 seconds (1251.6300 wall clock)
---User Time--- --System Time-- --User+System-- ---Wall Time--- --- Name
---
404.7200 ( 96.1%) 40.6383 ( 88.8%) 445.3583 ( 95.4%) 471.9647 ( 37.7%)
Clang front-end timer
15.2098 ( 3.6%) 3.3586 ( 7.3%) 18.5684 ( 4.0%) 398.1242 ( 31.8%)
Reading modules
420.9899 (100.0%) 45.7474 (100.0%) 466.7373 (100.0%) 1251.6300 (100.0%)
Total
```
`perf record -g` / `perf report` give the following picture:
```
Children Self Command Shared Object Symbol
+ 94.85% 0.00% clang clang [.]
clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformCallExpr(clang::CallExpr*) [clone
.__uniq.16014532493918845222783194145290083557] ◆
+ 93.47% 0.00% clang clang [.]
clang::Sema::InstantiateFunctionDefinition(clang::SourceLocation,
clang::FunctionDecl*, bool, bool, bool)
▒
+ 93.37% 83.51% clang clang [.]
clang::ASTReader::LoadExternalSpecializations(clang::Decl const*, bool)
▒
+ 93.19% 0.00% clang clang [.]
clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformCompoundStmt(clang::CompoundStmt*,
bool) [clone .__uniq.16014532493918845222783194▒
+ 93.08% 0.00% clang clang [.]
clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformUnresolvedLookupExpr(clang::UnresolvedLookupExpr*,
bool) [clone .__uniq.1601453249▒
+ 92.98% 0.00% clang clang [.]
clang::Sema::BuildTemplateIdExpr(clang::CXXScopeSpec const&,
clang::SourceLocation, clang::LookupResult&, bool,
clang::TemplateArgumentListInfo const*) ▒
+ 92.44% 0.00% clang clang [.]
clang::Sema::CheckVarTemplateId(clang::VarTemplateDecl*, clang::SourceLocation,
clang::SourceLocation, clang::TemplateArgumentListInfo const&) ▒
+ 92.08% 0.00% clang clang [.]
clang::Sema::InstantiateVariableInitializer(clang::VarDecl*, clang::VarDecl*,
clang::MultiLevelTemplateArgumentList const&)
▒
+ 91.87% 0.00% clang clang [.]
clang::VarTemplateDecl::getPartialSpecializations(llvm::SmallVectorImpl<clang::VarTemplatePartialSpecializationDecl*>&)
const ▒
+ 91.18% 0.00% clang clang [.]
clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformBinaryOperator(clang::BinaryOperator*)
[clone .__uniq.1601453249391884522278319414▒
+ 91.07% 0.00% clang clang [.]
clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformExprs(clang::Expr* const*, unsigned
int, bool, llvm::SmallVectorImpl<clang::Expr*>▒
+ 90.70% 0.01% clang clang [.]
clang::Sema::InstantiateVariableDefinition(clang::SourceLocation,
clang::VarDecl*, bool, bool, bool)
▒
+ 90.41% 0.01% clang clang [.]
clang::Sema::BuildDeclarationNameExpr(clang::CXXScopeSpec const&,
clang::DeclarationNameInfo const&, clang::NamedDecl*, clang::NamedDecl*,
clang::TemplateArgu▒
+ 90.29% 0.00% clang clang [.]
clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformInitListExpr(clang::InitListExpr*)
[clone .__uniq.16014532493918845222783194145290▒
+ 89.92% 0.00% clang clang [.]
clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformParenExpr(clang::ParenExpr*) [clone
.__uniq.16014532493918845222783194145290083557▒
+ 89.23% 0.00% clang clang [.]
clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformConditionalOperator(clang::ConditionalOperator*)
[clone .__uniq.160145324939188452▒
+ 84.49% 0.02% clang clang [.]
clang::Sema::RequireCompleteTypeImpl(clang::SourceLocation, clang::QualType,
clang::Sema::CompleteTypeKind, clang::Sema::TypeDiagnoser*)
▒
+ 84.47% 0.00% clang clang [.]
clang::Sema::InstantiateClassTemplateSpecialization(clang::SourceLocation,
clang::ClassTemplateSpecializationDecl*, clang::TemplateSpecializationKind,
bool) ▒
+ 84.07% 0.01% clang clang [.]
clang::Sema::InstantiateClass(clang::SourceLocation, clang::CXXRecordDecl*,
clang::CXXRecordDecl*, clang::MultiLevelTemplateArgumentList const&,
clang::Templa▒
+ 82.84% 0.02% clang clang [.]
clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformType(clang::TypeLocBuilder&,
clang::TypeLoc) [clone .__uniq.1601453249391884522278▒
+ 82.23% 0.02% clang clang [.]
clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformTemplateSpecializationType(clang::TypeLocBuilder&,
clang::TemplateSpecializationTy▒
+ 81.99% 0.01% clang clang [.] (anonymous
namespace)::TemplateInstantiator::TransformTemplateArgument(clang::TemplateArgumentLoc
const&, clang::TemplateArgumentLoc&, bool) [clone .__uniq.16▒
+ 81.54% 0.00% clang clang [.]
clang::Sema::RequireCompleteDeclContext(clang::CXXScopeSpec&,
clang::DeclContext*)
▒
+ 80.18% 0.01% clang clang [.]
clang::TreeTransform<(anonymous
namespace)::TemplateInstantiator>::TransformType(clang::TypeSourceInfo*) [clone
.__uniq.16014532493918845222783194145290083557▒
+ 79.88% 0.12% clang clang [.]
clang::Sema::CheckTemplateIdType(clang::TemplateName, clang::SourceLocation,
clang::TemplateArgumentListInfo&)
▒
```
I can try to build clang with better debug information and get a higher
fidelity profile, but hopefully this already shows the direction to look at.
https://github.com/llvm/llvm-project/pull/83237
_______________________________________________
llvm-branch-commits mailing list
llvm-branch-commits@lists.llvm.org
https://lists.llvm.org/cgi-bin/mailman/listinfo/llvm-branch-commits
