commit 2e6dc538be1a694ad569496b917c5e653ed21c1d
author Bruno Ricci <riccibrun@gmail.com> Tue Jan 08 14:17:00 2019 +0000
committer Bruno Ricci <riccibrun@gmail.com> Tue Jan 08 14:17:00 2019 +0000
tree e0407023bab922c4a3412c0566620e2e220f2b16
parent efb5ad1c58e2fe758af3fd2a2f9a8c1196552864

[AST] Pack CXXDependentScopeMemberExpr

Use the newly available space in the bit-fields of Stmt. Additionally store
FirstQualifierFoundInScope as a trailing object since it is most of the time
null (non-null for 2 of the 35446 CXXDependentScopeMemberExpr when parsing
all of Boost).

It would be possible to move the data for the nested-name-specifier to a
trailing object too to save another 2 pointers, however doing so did actually
regress the time taken to parse all of Boost slightly.

This saves 8 bytes + 1 pointer per CXXDependentScopeMemberExpr in the vast
majority of cases.

Differential Revision: https://reviews.llvm.org/D56367

Reviewed By: rjmccall

llvm-svn: 350625

clang/lib/Serialization/ASTReaderStmt.cpp

diff --git a/clang/lib/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index 80b987a..53eb5bc 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -1584,22 +1584,37 @@
   E->SubExpr = Record.readSubExpr();
 }
 
-void
-ASTStmtReader::VisitCXXDependentScopeMemberExpr(CXXDependentScopeMemberExpr *E){
+void ASTStmtReader::VisitCXXDependentScopeMemberExpr(
+    CXXDependentScopeMemberExpr *E) {
   VisitExpr(E);
 
-  if (Record.readInt()) // HasTemplateKWAndArgsInfo
+  bool HasTemplateKWAndArgsInfo = Record.readInt();
+  unsigned NumTemplateArgs = Record.readInt();
+  bool HasFirstQualifierFoundInScope = Record.readInt();
+
+  assert((HasTemplateKWAndArgsInfo == E->hasTemplateKWAndArgsInfo()) &&
+         "Wrong HasTemplateKWAndArgsInfo!");
+  assert(
+      (HasFirstQualifierFoundInScope == E->hasFirstQualifierFoundInScope()) &&
+      "Wrong HasFirstQualifierFoundInScope!");
+
+  if (HasTemplateKWAndArgsInfo)
     ReadTemplateKWAndArgsInfo(
         *E->getTrailingObjects<ASTTemplateKWAndArgsInfo>(),
-        E->getTrailingObjects<TemplateArgumentLoc>(),
-        /*NumTemplateArgs=*/Record.readInt());
+        E->getTrailingObjects<TemplateArgumentLoc>(), NumTemplateArgs);
 
-  E->Base = Record.readSubExpr();
+  assert((NumTemplateArgs == E->getNumTemplateArgs()) &&
+         "Wrong NumTemplateArgs!");
+
+  E->CXXDependentScopeMemberExprBits.IsArrow = Record.readInt();
+  E->CXXDependentScopeMemberExprBits.OperatorLoc = ReadSourceLocation();
   E->BaseType = Record.readType();
-  E->IsArrow = Record.readInt();
-  E->OperatorLoc = ReadSourceLocation();
   E->QualifierLoc = Record.readNestedNameSpecifierLoc();
-  E->FirstQualifierFoundInScope = ReadDeclAs<NamedDecl>();
+  E->Base = Record.readSubExpr();
+
+  if (HasFirstQualifierFoundInScope)
+    *E->getTrailingObjects<NamedDecl *>() = ReadDeclAs<NamedDecl>();
+
   ReadDeclarationNameInfo(E->MemberNameInfo);
 }
 
@@ -3224,11 +3239,12 @@
       break;
 
     case EXPR_CXX_DEPENDENT_SCOPE_MEMBER:
-      S = CXXDependentScopeMemberExpr::CreateEmpty(Context,
-         /*HasTemplateKWAndArgsInfo=*/Record[ASTStmtReader::NumExprFields],
-                  /*NumTemplateArgs=*/Record[ASTStmtReader::NumExprFields]
-                                   ? Record[ASTStmtReader::NumExprFields + 1]
-                                   : 0);
+      S = CXXDependentScopeMemberExpr::CreateEmpty(
+          Context,
+          /*HasTemplateKWAndArgsInfo=*/Record[ASTStmtReader::NumExprFields],
+          /*NumTemplateArgs=*/Record[ASTStmtReader::NumExprFields + 1],
+          /*HasFirstQualifierFoundInScope=*/
+          Record[ASTStmtReader::NumExprFields + 2]);
       break;
 
     case EXPR_CXX_DEPENDENT_SCOPE_DECL_REF:

clang/lib/Serialization/ASTWriterStmt.cpp

diff --git a/clang/lib/Serialization/ASTWriterStmt.cpp b/clang/lib/Serialization/ASTWriterStmt.cpp
index 14c3b32..b1908f79 100644
--- a/clang/lib/Serialization/ASTWriterStmt.cpp
+++ b/clang/lib/Serialization/ASTWriterStmt.cpp
@@ -1554,31 +1554,36 @@
   Code = serialization::EXPR_EXPR_WITH_CLEANUPS;
 }
 
-void
-ASTStmtWriter::VisitCXXDependentScopeMemberExpr(CXXDependentScopeMemberExpr *E){
+void ASTStmtWriter::VisitCXXDependentScopeMemberExpr(
+    CXXDependentScopeMemberExpr *E) {
   VisitExpr(E);
 
-  // Don't emit anything here, HasTemplateKWAndArgsInfo must be
-  // emitted first.
+  // Don't emit anything here (or if you do you will have to update
+  // the corresponding deserialization function).
 
-  Record.push_back(E->HasTemplateKWAndArgsInfo);
-  if (E->HasTemplateKWAndArgsInfo) {
+  Record.push_back(E->hasTemplateKWAndArgsInfo());
+  Record.push_back(E->getNumTemplateArgs());
+  Record.push_back(E->hasFirstQualifierFoundInScope());
+
+  if (E->hasTemplateKWAndArgsInfo()) {
     const ASTTemplateKWAndArgsInfo &ArgInfo =
         *E->getTrailingObjects<ASTTemplateKWAndArgsInfo>();
-    Record.push_back(ArgInfo.NumTemplateArgs);
     AddTemplateKWAndArgsInfo(ArgInfo,
                              E->getTrailingObjects<TemplateArgumentLoc>());
   }
 
+  Record.push_back(E->isArrow());
+  Record.AddSourceLocation(E->getOperatorLoc());
+  Record.AddTypeRef(E->getBaseType());
+  Record.AddNestedNameSpecifierLoc(E->getQualifierLoc());
   if (!E->isImplicitAccess())
     Record.AddStmt(E->getBase());
   else
     Record.AddStmt(nullptr);
-  Record.AddTypeRef(E->getBaseType());
-  Record.push_back(E->isArrow());
-  Record.AddSourceLocation(E->getOperatorLoc());
-  Record.AddNestedNameSpecifierLoc(E->getQualifierLoc());
-  Record.AddDeclRef(E->getFirstQualifierFoundInScope());
+
+  if (E->hasFirstQualifierFoundInScope())
+    Record.AddDeclRef(E->getFirstQualifierFoundInScope());
+
   Record.AddDeclarationNameInfo(E->MemberNameInfo);
   Code = serialization::EXPR_CXX_DEPENDENT_SCOPE_MEMBER;
 }