Optimize serialized representation of redeclarable declarations for

which there are no redeclarations. This reduced by size of the PCH
file for Cocoa.h by ~650k: ~536k of that was in the new
LOCAL_REDECLARATIONS table, which went from a ridiculous 540k down to
an acceptable 3.5k, while the rest was due to the more compact
abbreviated representation of redeclarable declaration kinds (which no
longer need to store the 'first' declaration ID).


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@146869 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 16 insertions, 39 deletions

diff --git a/lib/Serialization/ASTWriterDecl.cpp b/lib/Serialization/ASTWriterDecl.cpp
index 4e9a315d22..bb4359a54b 100644
--- a/lib/Serialization/ASTWriterDecl.cpp
+++ b/lib/Serialization/ASTWriterDecl.cpp
@@ -126,30 +126,6 @@ namespace clang {
   };
 }
 
-static bool isFirstDeclInFile(Decl *D) {
-  // FIXME: There must be a better way to abstract Redeclarable<T> into a 
-  // more-general "redeclarable type".
-  if (TagDecl *Tag = dyn_cast<TagDecl>(D))
-    return !Tag->getPreviousDeclaration() ||
-           Tag->getPreviousDeclaration()->isFromASTFile();
-  if (FunctionDecl *FD = dyn_cast<FunctionDecl>(D))
-    return !FD->getPreviousDeclaration() ||
-           FD->getPreviousDeclaration()->isFromASTFile();
-  if (VarDecl *VD = dyn_cast<VarDecl>(D))
-    return !VD->getPreviousDeclaration() ||
-           VD->getPreviousDeclaration()->isFromASTFile();
-  if (TypedefNameDecl *TD = dyn_cast<TypedefNameDecl>(D))
-    return !TD->getPreviousDeclaration() ||
-           TD->getPreviousDeclaration()->isFromASTFile();
-  if (ObjCInterfaceDecl *ID = dyn_cast<ObjCInterfaceDecl>(D))
-    return !ID->getPreviousDeclaration() ||
-            ID->getPreviousDeclaration()->isFromASTFile();
-  
-  RedeclarableTemplateDecl *RTD = cast<RedeclarableTemplateDecl>(D);
-  return !RTD->getPreviousDeclaration() ||
-          RTD->getPreviousDeclaration()->isFromASTFile();  
-}
-
 void ASTDeclWriter::Visit(Decl *D) {
   DeclVisitor<ASTDeclWriter>::Visit(D);
 
@@ -212,7 +188,7 @@ void ASTDeclWriter::VisitTypedefDecl(TypedefDecl *D) {
   if (!D->hasAttrs() &&
       !D->isImplicit() &&
       !D->isUsed(false) &&
-      isFirstDeclInFile(D) &&
+      D->RedeclLink.getPointer() == D &&
       !D->isInvalidDecl() &&
       !D->isReferenced() &&
       !D->isTopLevelDeclInObjCContainer() &&
@@ -262,7 +238,7 @@ void ASTDeclWriter::VisitEnumDecl(EnumDecl *D) {
       !D->isImplicit() &&
       !D->isUsed(false) &&
       !D->hasExtInfo() &&
-      isFirstDeclInFile(D) &&
+      D->RedeclLink.getPointer() == D &&
       !D->isInvalidDecl() &&
       !D->isReferenced() &&
       !D->isTopLevelDeclInObjCContainer() &&
@@ -286,7 +262,7 @@ void ASTDeclWriter::VisitRecordDecl(RecordDecl *D) {
       !D->isImplicit() &&
       !D->isUsed(false) &&
       !D->hasExtInfo() &&
-      isFirstDeclInFile(D) &&
+      D->RedeclLink.getPointer() == D &&
       !D->isInvalidDecl() &&
       !D->isReferenced() &&
       !D->isTopLevelDeclInObjCContainer() &&
@@ -732,7 +708,7 @@ void ASTDeclWriter::VisitVarDecl(VarDecl *D) {
       !D->isModulePrivate() &&
       D->getDeclName().getNameKind() == DeclarationName::Identifier &&
       !D->hasExtInfo() &&
-      isFirstDeclInFile(D) &&
+      D->RedeclLink.getPointer() == D &&
       !D->hasCXXDirectInitializer() &&
       D->getInit() == 0 &&
       !isa<ParmVarDecl>(D) &&
@@ -1298,7 +1274,13 @@ void ASTDeclWriter::VisitDeclContext(DeclContext *DC, uint64_t LexicalOffset,
 
 template <typename T>
 void ASTDeclWriter::VisitRedeclarable(Redeclarable<T> *D) {
-  enum { FirstInFile, PointsToPrevious };
+  enum { OnlyDeclaration = 0, FirstInFile, PointsToPrevious };
+  if (D->RedeclLink.getPointer() == D) {
+    // This is the only declaration.
+    Record.push_back(OnlyDeclaration);
+    return;
+  }
+  
   T *First = D->getFirstDeclaration();
   if (!D->getPreviousDeclaration() ||
       D->getPreviousDeclaration()->isFromASTFile()) {
@@ -1399,8 +1381,7 @@ void ASTWriter::WriteDeclsBlockAbbrevs() {
   Abv = new BitCodeAbbrev();
   Abv->Add(BitCodeAbbrevOp(serialization::DECL_ENUM));
   // Redeclarable
-  Abv->Add(BitCodeAbbrevOp(0));                       // First in file
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // First ID
+  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
@@ -1447,8 +1428,7 @@ void ASTWriter::WriteDeclsBlockAbbrevs() {
   Abv = new BitCodeAbbrev();
   Abv->Add(BitCodeAbbrevOp(serialization::DECL_RECORD));
   // Redeclarable
-  Abv->Add(BitCodeAbbrevOp(0));                       // First in file
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // First ID
+  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
@@ -1489,8 +1469,7 @@ void ASTWriter::WriteDeclsBlockAbbrevs() {
   Abv = new BitCodeAbbrev();
   Abv->Add(BitCodeAbbrevOp(serialization::DECL_PARM_VAR));
   // Redeclarable
-  Abv->Add(BitCodeAbbrevOp(0));                       // First in file
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // First ID
+  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
@@ -1540,8 +1519,7 @@ void ASTWriter::WriteDeclsBlockAbbrevs() {
   Abv = new BitCodeAbbrev();
   Abv->Add(BitCodeAbbrevOp(serialization::DECL_TYPEDEF));
   // Redeclarable
-  Abv->Add(BitCodeAbbrevOp(0));                       // First in file
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // First ID
+  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext
@@ -1569,8 +1547,7 @@ void ASTWriter::WriteDeclsBlockAbbrevs() {
   Abv = new BitCodeAbbrev();
   Abv->Add(BitCodeAbbrevOp(serialization::DECL_VAR));
   // Redeclarable
-  Abv->Add(BitCodeAbbrevOp(0));                       // First in file
-  Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // First ID
+  Abv->Add(BitCodeAbbrevOp(0));                       // No redeclaration
   // Decl
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // DeclContext
   Abv->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 6)); // LexicalDeclContext