[PATCH] D118608: [NFC] Increase initial size of FoldingSets used in ASTContext and CodeGenTypes

[Dawid Jurczak via Phabricator via cfe-commits]

yurai007 created this revision.
yurai007 added reviewers: nikic, xbolva00, aeubanks, ChuanqiXu, v.g.vassilev, serge-sans-paille.
yurai007 requested review of this revision.
Herald added a project: clang.
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Among many FoldingSet users most notable seem to be ASTContext and CodeGenTypes.
The reasons that we spend not-so-tiny amount of time in FoldingSet calls from there, are following:

      
  1. Default FoldingSet capacity for 2^6 items very often is not enough.
     For PointerTypes/ElaboratedTypes/ParenTypes it's not unlikely to observe growing it to 256 or 512 items.
     FunctionProtoTypes can easily exceed 1k items capacity growing up to 4k or even 8k size.
      
  2. FoldingSetBase::GrowBucketCount cost itself is not very bad (pure reallocations are rather cheap thanks to BumpPtrAllocator).
     What matters is high collision rate when lot of items end up in same bucket slowing down FoldingSetBase::FindNodeOrInsertPos and trashing CPU cache
     (as items with same hash are organized in intrusive linked list which need to be traversed).
   

This change address both issues by increasing initial size of FoldingSets used in ASTContext and CodeGenTypes.

Extracted from: https://reviews.llvm.org/D118385


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D118608

Files:
  clang/include/clang/AST/ASTContext.h
  clang/lib/AST/ASTContext.cpp
  clang/lib/CodeGen/CodeGenTypes.h


Index: clang/lib/CodeGen/CodeGenTypes.h
===================================================================
--- clang/lib/CodeGen/CodeGenTypes.h
+++ clang/lib/CodeGen/CodeGenTypes.h
@@ -76,7 +76,7 @@
   llvm::DenseMap<const Type*, llvm::StructType *> RecordDeclTypes;
 
   /// Hold memoized CGFunctionInfo results.
-  llvm::FoldingSet<CGFunctionInfo> FunctionInfos;
+  llvm::FoldingSet<CGFunctionInfo> FunctionInfos{FunctionInfosLog2InitSize};
 
   /// This set keeps track of records that we're currently converting
   /// to an IR type.  For example, when converting:
@@ -98,6 +98,7 @@
 
   llvm::SmallSet<const Type *, 8> RecordsWithOpaqueMemberPointers;
 
+  static constexpr unsigned FunctionInfosLog2InitSize = 9;
   /// Helper for ConvertType.
   llvm::Type *ConvertFunctionTypeInternal(QualType FT);
 
Index: clang/lib/AST/ASTContext.cpp
===================================================================
--- clang/lib/AST/ASTContext.cpp
+++ clang/lib/AST/ASTContext.cpp
@@ -973,7 +973,8 @@
 ASTContext::ASTContext(LangOptions &LOpts, SourceManager &SM,
                        IdentifierTable &idents, SelectorTable &sels,
                        Builtin::Context &builtins, TranslationUnitKind TUKind)
-    : ConstantArrayTypes(this_()), FunctionProtoTypes(this_()),
+    : ConstantArrayTypes(this_(), ConstantArrayTypesLog2InitSize),
+      FunctionProtoTypes(this_(), FunctionProtoTypesLog2InitSize),
       TemplateSpecializationTypes(this_()),
       DependentTemplateSpecializationTypes(this_()), AutoTypes(this_()),
       SubstTemplateTemplateParmPacks(this_()),
Index: clang/include/clang/AST/ASTContext.h
===================================================================
--- clang/include/clang/AST/ASTContext.h
+++ clang/include/clang/AST/ASTContext.h
@@ -211,7 +211,7 @@
   mutable SmallVector<Type *, 0> Types;
   mutable llvm::FoldingSet<ExtQuals> ExtQualNodes;
   mutable llvm::FoldingSet<ComplexType> ComplexTypes;
-  mutable llvm::FoldingSet<PointerType> PointerTypes;
+  mutable llvm::FoldingSet<PointerType> PointerTypes{GeneralTypesLog2InitSize};
   mutable llvm::FoldingSet<AdjustedType> AdjustedTypes;
   mutable llvm::FoldingSet<BlockPointerType> BlockPointerTypes;
   mutable llvm::FoldingSet<LValueReferenceType> LValueReferenceTypes;
@@ -243,9 +243,10 @@
     SubstTemplateTypeParmPackTypes;
   mutable llvm::ContextualFoldingSet<TemplateSpecializationType, ASTContext&>
     TemplateSpecializationTypes;
-  mutable llvm::FoldingSet<ParenType> ParenTypes;
+  mutable llvm::FoldingSet<ParenType> ParenTypes{GeneralTypesLog2InitSize};
   mutable llvm::FoldingSet<UsingType> UsingTypes;
-  mutable llvm::FoldingSet<ElaboratedType> ElaboratedTypes;
+  mutable llvm::FoldingSet<ElaboratedType> ElaboratedTypes{
+      GeneralTypesLog2InitSize};
   mutable llvm::FoldingSet<DependentNameType> DependentNameTypes;
   mutable llvm::ContextualFoldingSet<DependentTemplateSpecializationType,
                                      ASTContext&>
@@ -466,6 +467,10 @@
   };
   llvm::DenseMap<Module*, PerModuleInitializers*> ModuleInitializers;
 
+  static constexpr unsigned ConstantArrayTypesLog2InitSize = 8;
+  static constexpr unsigned GeneralTypesLog2InitSize = 9;
+  static constexpr unsigned FunctionProtoTypesLog2InitSize = 12;
+
   ASTContext &this_() { return *this; }
 
 public:


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