r268817 - [modules] Attempt to improve performance for declaration merging without a Sema

[Richard Smith via cfe-commits]

Author: rsmith
Date: Fri May  6 18:14:07 2016
New Revision: 268817

URL: http://llvm.org/viewvc/llvm-project?rev=268817&view=rev
Log:
[modules] Attempt to improve performance for declaration merging without a Sema
object in C. Rather than using the DeclContext (which is very slow because it
triggers us to build a lookup table for the DeclContext), use a separate map
from identifiers to decls for this case, containing only the ones we've
actually deserialized. For convenience, this map is implemented as an
IdentifierResolver.

Modified:
    cfe/trunk/include/clang/Serialization/ASTReader.h
    cfe/trunk/lib/Serialization/ASTReader.cpp
    cfe/trunk/lib/Serialization/ASTReaderDecl.cpp

Modified: cfe/trunk/include/clang/Serialization/ASTReader.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Serialization/ASTReader.h?rev=268817&r1=268816&r2=268817&view=diff
==============================================================================
--- cfe/trunk/include/clang/Serialization/ASTReader.h (original)
+++ cfe/trunk/include/clang/Serialization/ASTReader.h Fri May  6 18:14:07 2016
@@ -27,6 +27,7 @@
 #include "clang/Lex/HeaderSearch.h"
 #include "clang/Lex/PreprocessingRecord.h"
 #include "clang/Sema/ExternalSemaSource.h"
+#include "clang/Sema/IdentifierResolver.h"
 #include "clang/Serialization/ASTBitCodes.h"
 #include "clang/Serialization/ContinuousRangeMap.h"
 #include "clang/Serialization/Module.h"
@@ -390,6 +391,11 @@ private:
   /// \brief The module manager which manages modules and their dependencies
   ModuleManager ModuleMgr;
 
+  /// \brief A dummy identifier resolver used to merge TU-scope declarations in
+  /// C, for the cases where we don't have a Sema object to provide a real
+  /// identifier resolver.
+  IdentifierResolver DummyIdResolver;
+
   /// A mapping from extension block names to module file extensions.
   llvm::StringMap<IntrusiveRefCntPtr<ModuleFileExtension>> ModuleFileExtensions;
 
@@ -2100,6 +2106,11 @@ public:
   /// imported.
   Sema *getSema() { return SemaObj; }
 
+  /// \brief Get the identifier resolver used for name lookup / updates
+  /// in the translation unit scope. We have one of these even if we don't
+  /// have a Sema object.
+  IdentifierResolver &getIdResolver();
+
   /// \brief Retrieve the identifier table associated with the
   /// preprocessor.
   IdentifierTable &getIdentifierTable();

Modified: cfe/trunk/lib/Serialization/ASTReader.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ASTReader.cpp?rev=268817&r1=268816&r2=268817&view=diff
==============================================================================
--- cfe/trunk/lib/Serialization/ASTReader.cpp (original)
+++ cfe/trunk/lib/Serialization/ASTReader.cpp Fri May  6 18:14:07 2016
@@ -8695,6 +8695,7 @@ ASTReader::ASTReader(
       FileMgr(PP.getFileManager()), PCHContainerRdr(PCHContainerRdr),
       Diags(PP.getDiagnostics()), SemaObj(nullptr), PP(PP), Context(Context),
       Consumer(nullptr), ModuleMgr(PP.getFileManager(), PCHContainerRdr),
+      DummyIdResolver(PP),
       ReadTimer(std::move(ReadTimer)),
       PragmaMSStructState(-1),
       PragmaMSPointersToMembersState(-1),
@@ -8733,3 +8734,7 @@ ASTReader::~ASTReader() {
   if (OwnsDeserializationListener)
     delete DeserializationListener;
 }
+
+IdentifierResolver &ASTReader::getIdResolver() {
+  return SemaObj ? SemaObj->IdResolver : DummyIdResolver;
+}

Modified: cfe/trunk/lib/Serialization/ASTReaderDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ASTReaderDecl.cpp?rev=268817&r1=268816&r2=268817&view=diff
==============================================================================
--- cfe/trunk/lib/Serialization/ASTReaderDecl.cpp (original)
+++ cfe/trunk/lib/Serialization/ASTReaderDecl.cpp Fri May  6 18:14:07 2016
@@ -23,7 +23,6 @@
 #include "clang/AST/DeclVisitor.h"
 #include "clang/AST/Expr.h"
 #include "clang/Sema/IdentifierResolver.h"
-#include "clang/Sema/Sema.h"
 #include "clang/Sema/SemaDiagnostic.h"
 #include "llvm/Support/SaveAndRestore.h"
 
@@ -2814,9 +2813,9 @@ ASTDeclReader::FindExistingResult::~Find
   if (needsAnonymousDeclarationNumber(New)) {
     setAnonymousDeclForMerging(Reader, New->getLexicalDeclContext(),
                                AnonymousDeclNumber, New);
-  } else if (DC->isTranslationUnit() && Reader.SemaObj &&
+  } else if (DC->isTranslationUnit() &&
              !Reader.getContext().getLangOpts().CPlusPlus) {
-    if (Reader.SemaObj->IdResolver.tryAddTopLevelDecl(New, Name))
+    if (Reader.getIdResolver().tryAddTopLevelDecl(New, Name))
       Reader.PendingFakeLookupResults[Name.getAsIdentifierInfo()]
             .push_back(New);
   } else if (DeclContext *MergeDC = getPrimaryContextForMerging(Reader, DC)) {
@@ -2919,9 +2918,9 @@ ASTDeclReader::FindExistingResult ASTDec
       if (isSameEntity(Existing, D))
         return FindExistingResult(Reader, D, Existing, AnonymousDeclNumber,
                                   TypedefNameForLinkage);
-  } else if (DC->isTranslationUnit() && Reader.SemaObj &&
+  } else if (DC->isTranslationUnit() &&
              !Reader.getContext().getLangOpts().CPlusPlus) {
-    IdentifierResolver &IdResolver = Reader.SemaObj->IdResolver;
+    IdentifierResolver &IdResolver = Reader.getIdResolver();
 
     // Temporarily consider the identifier to be up-to-date. We don't want to
     // cause additional lookups here.