[AST] Store the results in OverloadExpr in a trailing array

Use the newly available space in the bit-fields of Stmt to pack
OverloadExpr, UnresolvedLookupExpr and UnresolvedMemberExpr.

Additionally store the results in the overload set in a trailing array.
This saves 1 pointer + 8 bytes per UnresolvedLookupExpr and
UnresolvedMemberExpr.

Differential Revision: https://reviews.llvm.org/D56368

Reviewed By: rjmccall

llvm-svn: 350732

2 files changed, 46 insertions, 28 deletions

diff --git a/clang/lib/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index b4b2965f12e..60abea95bfa 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -1648,19 +1648,33 @@ ASTStmtReader::VisitCXXUnresolvedConstructExpr(CXXUnresolvedConstructExpr *E) {
 void ASTStmtReader::VisitOverloadExpr(OverloadExpr *E) {
   VisitExpr(E);
 
-  if (Record.readInt()) // HasTemplateKWAndArgsInfo
+  unsigned NumResults = Record.readInt();
+  bool HasTemplateKWAndArgsInfo = Record.readInt();
+  assert((E->getNumDecls() == NumResults) && "Wrong NumResults!");
+  assert((E->hasTemplateKWAndArgsInfo() == HasTemplateKWAndArgsInfo) &&
+         "Wrong HasTemplateKWAndArgsInfo!");
+
+  if (HasTemplateKWAndArgsInfo) {
+    unsigned NumTemplateArgs = Record.readInt();
     ReadTemplateKWAndArgsInfo(*E->getTrailingASTTemplateKWAndArgsInfo(),
                               E->getTrailingTemplateArgumentLoc(),
-                              /*NumTemplateArgs=*/Record.readInt());
+                              NumTemplateArgs);
+    assert((E->getNumTemplateArgs() == NumTemplateArgs) &&
+           "Wrong NumTemplateArgs!");
+  }
 
-  unsigned NumDecls = Record.readInt();
   UnresolvedSet<8> Decls;
-  for (unsigned i = 0; i != NumDecls; ++i) {
+  for (unsigned I = 0; I != NumResults; ++I) {
     auto *D = ReadDeclAs<NamedDecl>();
     auto AS = (AccessSpecifier)Record.readInt();
     Decls.addDecl(D, AS);
   }
-  E->initializeResults(Record.getContext(), Decls.begin(), Decls.end());
+
+  DeclAccessPair *Results = E->getTrailingResults();
+  UnresolvedSetIterator Iter = Decls.begin();
+  for (unsigned I = 0; I != NumResults; ++I) {
+    Results[I] = (Iter + I).getPair();
+  }
 
   ReadDeclarationNameInfo(E->NameInfo);
   E->QualifierLoc = Record.readNestedNameSpecifierLoc();
@@ -1668,8 +1682,8 @@ void ASTStmtReader::VisitOverloadExpr(OverloadExpr *E) {
 
 void ASTStmtReader::VisitUnresolvedMemberExpr(UnresolvedMemberExpr *E) {
   VisitOverloadExpr(E);
-  E->IsArrow = Record.readInt();
-  E->HasUnresolvedUsing = Record.readInt();
+  E->UnresolvedMemberExprBits.IsArrow = Record.readInt();
+  E->UnresolvedMemberExprBits.HasUnresolvedUsing = Record.readInt();
   E->Base = Record.readSubExpr();
   E->BaseType = Record.readType();
   E->OperatorLoc = ReadSourceLocation();
@@ -1677,8 +1691,8 @@ void ASTStmtReader::VisitUnresolvedMemberExpr(UnresolvedMemberExpr *E) {
 
 void ASTStmtReader::VisitUnresolvedLookupExpr(UnresolvedLookupExpr *E) {
   VisitOverloadExpr(E);
-  E->RequiresADL = Record.readInt();
-  E->Overloaded = Record.readInt();
+  E->UnresolvedLookupExprBits.RequiresADL = Record.readInt();
+  E->UnresolvedLookupExprBits.Overloaded = Record.readInt();
   E->NamingClass = ReadDeclAs<CXXRecordDecl>();
 }
 
@@ -3261,19 +3275,25 @@ Stmt *ASTReader::ReadStmtFromStream(ModuleFile &F) {
       break;
 
     case EXPR_CXX_UNRESOLVED_MEMBER:
-      S = UnresolvedMemberExpr::CreateEmpty(Context,
-         /*HasTemplateKWAndArgsInfo=*/Record[ASTStmtReader::NumExprFields],
-                  /*NumTemplateArgs=*/Record[ASTStmtReader::NumExprFields]
-                                   ? Record[ASTStmtReader::NumExprFields + 1]
-                                   : 0);
+      S = UnresolvedMemberExpr::CreateEmpty(
+          Context,
+          /*NumResults=*/Record[ASTStmtReader::NumExprFields],
+          /*HasTemplateKWAndArgsInfo=*/Record[ASTStmtReader::NumExprFields + 1],
+          /*NumTemplateArgs=*/
+          Record[ASTStmtReader::NumExprFields + 1]
+              ? Record[ASTStmtReader::NumExprFields + 2]
+              : 0);
       break;
 
     case EXPR_CXX_UNRESOLVED_LOOKUP:
-      S = UnresolvedLookupExpr::CreateEmpty(Context,
-         /*HasTemplateKWAndArgsInfo=*/Record[ASTStmtReader::NumExprFields],
-                  /*NumTemplateArgs=*/Record[ASTStmtReader::NumExprFields]
-                                   ? Record[ASTStmtReader::NumExprFields + 1]
-                                   : 0);
+      S = UnresolvedLookupExpr::CreateEmpty(
+          Context,
+          /*NumResults=*/Record[ASTStmtReader::NumExprFields],
+          /*HasTemplateKWAndArgsInfo=*/Record[ASTStmtReader::NumExprFields + 1],
+          /*NumTemplateArgs=*/
+          Record[ASTStmtReader::NumExprFields + 1]
+              ? Record[ASTStmtReader::NumExprFields + 2]
+              : 0);
       break;
 
     case EXPR_TYPE_TRAIT:
diff --git a/clang/lib/Serialization/ASTWriterStmt.cpp b/clang/lib/Serialization/ASTWriterStmt.cpp
index b1908f79912..6f8b86edcdf 100644
--- a/clang/lib/Serialization/ASTWriterStmt.cpp
+++ b/clang/lib/Serialization/ASTWriterStmt.cpp
@@ -1625,25 +1625,23 @@ ASTStmtWriter::VisitCXXUnresolvedConstructExpr(CXXUnresolvedConstructExpr *E) {
 void ASTStmtWriter::VisitOverloadExpr(OverloadExpr *E) {
   VisitExpr(E);
 
-  // Don't emit anything here, HasTemplateKWAndArgsInfo must be
-  // emitted first.
-
-  Record.push_back(E->HasTemplateKWAndArgsInfo);
-  if (E->HasTemplateKWAndArgsInfo) {
+  Record.push_back(E->getNumDecls());
+  Record.push_back(E->hasTemplateKWAndArgsInfo());
+  if (E->hasTemplateKWAndArgsInfo()) {
     const ASTTemplateKWAndArgsInfo &ArgInfo =
         *E->getTrailingASTTemplateKWAndArgsInfo();
     Record.push_back(ArgInfo.NumTemplateArgs);
     AddTemplateKWAndArgsInfo(ArgInfo, E->getTrailingTemplateArgumentLoc());
   }
 
-  Record.push_back(E->getNumDecls());
-  for (OverloadExpr::decls_iterator
-         OvI = E->decls_begin(), OvE = E->decls_end(); OvI != OvE; ++OvI) {
+  for (OverloadExpr::decls_iterator OvI = E->decls_begin(),
+                                    OvE = E->decls_end();
+       OvI != OvE; ++OvI) {
     Record.AddDeclRef(OvI.getDecl());
     Record.push_back(OvI.getAccess());
   }
 
-  Record.AddDeclarationNameInfo(E->NameInfo);
+  Record.AddDeclarationNameInfo(E->getNameInfo());
   Record.AddNestedNameSpecifierLoc(E->getQualifierLoc());
 }