Make ASTContext explicitly keep track of the declaration for the C

FILE type, rather than using name lookup to find FILE within the
translation unit. Within precompiled headers, FILE is treated as yet
another "special type" (like __builtin_va_list).

This change should provide a performance improvement (not verified),
since the lookup into the translation unit declaration 
forces the (otherwise unneeded) construction of a large hash table.
More importantly, with precompiled headers, the construction
of that table requires deserializing most of the top-level
declarations from the precompiled header, which are then unused.

Fixes PR 4509.



git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@74911 91177308-0d34-0410-b5e6-96231b3b80d8

include/clang/AST/ASTContext.h

@@ -126,6 +126,9 @@ class ASTContext {
 
   RecordDecl *ObjCFastEnumerationStateTypeDecl;
   
+  /// \brief The type for the C FILE type.
+  TypeDecl *FILEDecl;
+  
   /// \brief Keeps track of all declaration attributes. 
   ///
   /// Since so few decls have attrs, we keep them in a hash map instead of
@@ -447,6 +450,16 @@ public:
 
   void setObjCFastEnumerationStateType(QualType T);
 
+  /// \brief Set the type for the C FILE type.
+  void setFILEDecl(TypeDecl *FILEDecl) { this->FILEDecl = FILEDecl; }
+  
+  /// \brief Retrieve the C FILE type.
+  QualType getFILEType() { 
+    if (FILEDecl) 
+      return getTypeDeclType(FILEDecl);
+    return QualType();
+  }
+                       
   /// getObjCEncodingForType - Emit the ObjC type encoding for the
   /// given type into \arg S. If \arg NameFields is specified then
   /// record field names are also encoded.

include/clang/Frontend/PCHBitCodes.h

@@ -419,7 +419,9 @@ namespace clang {
       /// \brief CFConstantString type
       SPECIAL_TYPE_CF_CONSTANT_STRING          = 5,
       /// \brief Objective-C fast enumeration state type
-      SPECIAL_TYPE_OBJC_FAST_ENUMERATION_STATE = 6
+      SPECIAL_TYPE_OBJC_FAST_ENUMERATION_STATE = 6,
+      /// \brief C FILE typedef type
+      SPECIAL_TYPE_FILE                        = 7
     };
 
     /// \brief Record codes for each kind of declaration.

lib/AST/ASTContext.cpp

@@ -36,7 +36,8 @@ ASTContext::ASTContext(const LangOptions& LOpts, SourceManager &SM,
                        Builtin::Context &builtins,
                        bool FreeMem, unsigned size_reserve) : 
   GlobalNestedNameSpecifier(0), CFConstantStringTypeDecl(0), 
-  ObjCFastEnumerationStateTypeDecl(0), SourceMgr(SM), LangOpts(LOpts), 
+  ObjCFastEnumerationStateTypeDecl(0), FILEDecl(0),
+  SourceMgr(SM), LangOpts(LOpts), 
   LoadedExternalComments(false), FreeMemory(FreeMem), Target(t), 
   Idents(idents), Selectors(sels),
   BuiltinInfo(builtins), ExternalSource(0), PrintingPolicy(LOpts) {  
@@ -3844,16 +3845,12 @@ static QualType DecodeTypeFromStr(const char *&Str, ASTContext &Context,
     break;
   }
   case 'P': {
-    IdentifierInfo *II = &Context.Idents.get("FILE");
-    DeclContext::lookup_result Lookup 
-      = Context.getTranslationUnitDecl()->lookup(II);
-    if (Lookup.first != Lookup.second && isa<TypeDecl>(*Lookup.first)) {
-      Type = Context.getTypeDeclType(cast<TypeDecl>(*Lookup.first));
-      break;
-    }
-    else {
+    Type = Context.getFILEType();
+    if (Type.isNull()) {
       Error = ASTContext::GE_Missing_FILE;
       return QualType();
+    } else {
+      break;
     }
   }
   }

lib/Frontend/PCHReader.cpp

@@ -1536,6 +1536,17 @@ void PCHReader::InitializeContext(ASTContext &Ctx) {
   if (unsigned FastEnum 
         = SpecialTypes[pch::SPECIAL_TYPE_OBJC_FAST_ENUMERATION_STATE])
     Context->setObjCFastEnumerationStateType(GetType(FastEnum));
+  if (unsigned File = SpecialTypes[pch::SPECIAL_TYPE_FILE]) {
+    QualType FileType = GetType(File);
+    assert(!FileType.isNull() && "FILE type is NULL");
+    if (const TypedefType *Typedef = FileType->getAsTypedefType())
+      Context->setFILEDecl(Typedef->getDecl());
+    else {
+      const TagType *Tag = FileType->getAsTagType();
+      assert(Tag && "Invalid FILE type in PCH file");
+      Context->setFILEDecl(Tag->getDecl());
+    }
+  }
 }
 
 /// \brief Retrieve the name of the original source file name

lib/Frontend/PCHWriter.cpp

@@ -1892,6 +1892,7 @@ void PCHWriter::WritePCH(Sema &SemaRef, MemorizeStatCalls *StatCalls,
   AddTypeRef(Context.getObjCClassType(), Record);
   AddTypeRef(Context.getRawCFConstantStringType(), Record);
   AddTypeRef(Context.getRawObjCFastEnumerationStateType(), Record);
+  AddTypeRef(Context.getFILEType(), Record);
   Stream.EmitRecord(pch::SPECIAL_TYPES, Record);
 
   // Write the record containing external, unnamed definitions.

lib/Sema/SemaDecl.cpp

@@ -1691,6 +1691,14 @@ Sema::ActOnTypedefDeclarator(Scope* S, Declarator& D, DeclContext* DC,
       }
     }
   }
+
+  // If this is the C FILE type, notify the AST context.
+  if (IdentifierInfo *II = NewTD->getIdentifier())
+    if (!NewTD->isInvalidDecl() &&
+        NewTD->getDeclContext()->getLookupContext()->isTranslationUnit() &&        
+        II->isStr("FILE"))
+      Context.setFILEDecl(NewTD);
+  
   return NewTD;
 }
 
@@ -3768,6 +3776,13 @@ CreateNewDecl:
     CurContext->addDecl(New);
   }
 
+  // If this is the C FILE type, notify the AST context.
+  if (IdentifierInfo *II = New->getIdentifier())
+    if (!New->isInvalidDecl() &&
+        New->getDeclContext()->getLookupContext()->isTranslationUnit() &&        
+        II->isStr("FILE"))
+      Context.setFILEDecl(New);
+  
   OwnedDecl = true;
   return DeclPtrTy::make(New);
 }

test/PCH/pr4489.c

@@ -1,7 +1,8 @@
 // RUN: clang -x c-header -o %t.pch %s &&
 // RUN: clang -include %t -x c /dev/null -emit-llvm -S -o -
 // PR 4489: Crash with PCH
-
+// PR 4492: Crash with PCH (round two)
+// PR 4509: Crash with PCH (round three)
 typedef struct _IO_FILE FILE;
 extern int fprintf (struct _IO_FILE *__restrict __stream,
                     __const char *__restrict __format, ...);
@@ -25,4 +26,15 @@ void x0(void)
 {
   extern char z0;
   fprintf (0, "a");
+}
+
+void x1(void)
+{
+  fprintf (0, "asdf");
+}
+
+void y1(void)
+{
+  extern char e;
+  fprintf (0, "asdf");
 }