[AST] Pack GenericSelectionExpr

Store the controlling expression, the association expressions and the
corresponding TypeSourceInfos as trailing objects.

Additionally use the bit-fields of Stmt to store one SourceLocation,
saving one additional pointer. This saves 3 pointers in total per
GenericSelectionExpr.

Differential Revision: https://reviews.llvm.org/D57104

Reviewed By: aaron.ballman

Reviewers: aaron.ballman, steveire
llvm-svn: 352276

2 files changed, 31 insertions, 22 deletions

diff --git a/clang/lib/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index 1974aa2f4bd..69c098c6ea4 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -1022,23 +1022,24 @@ void ASTStmtReader::VisitBlockExpr(BlockExpr *E) {
 
 void ASTStmtReader::VisitGenericSelectionExpr(GenericSelectionExpr *E) {
   VisitExpr(E);
-  E->NumAssocs = Record.readInt();
-  E->ResultIndex = Record.readInt();
-
-  E->AssocTypes = new (Record.getContext()) TypeSourceInfo *[E->NumAssocs];
-  E->SubExprs = new (Record.getContext())
-      Stmt *[GenericSelectionExpr::AssocExprStartIndex + E->NumAssocs];
-
-  E->SubExprs[GenericSelectionExpr::ControllingIndex] = Record.readSubExpr();
-  for (unsigned I = 0, N = E->getNumAssocs(); I != N; ++I) {
-    E->AssocTypes[I] = GetTypeSourceInfo();
-    E->SubExprs[GenericSelectionExpr::AssocExprStartIndex + I] =
-        Record.readSubExpr();
-  }
 
-  E->GenericLoc = ReadSourceLocation();
+  unsigned NumAssocs = Record.readInt();
+  assert(NumAssocs == E->getNumAssocs() && "Wrong NumAssocs!");
+  E->ResultIndex = Record.readInt();
+  E->GenericSelectionExprBits.GenericLoc = ReadSourceLocation();
   E->DefaultLoc = ReadSourceLocation();
   E->RParenLoc = ReadSourceLocation();
+
+  Stmt **Stmts = E->getTrailingObjects<Stmt *>();
+  // Add 1 to account for the controlling expression which is the first
+  // expression in the trailing array of Stmt *. This is not needed for
+  // the trailing array of TypeSourceInfo *.
+  for (unsigned I = 0, N = NumAssocs + 1; I < N; ++I)
+    Stmts[I] = Record.readSubExpr();
+
+  TypeSourceInfo **TSIs = E->getTrailingObjects<TypeSourceInfo *>();
+  for (unsigned I = 0, N = NumAssocs; I < N; ++I)
+    TSIs[I] = GetTypeSourceInfo();
 }
 
 void ASTStmtReader::VisitPseudoObjectExpr(PseudoObjectExpr *E) {
@@ -2677,7 +2678,9 @@ Stmt *ASTReader::ReadStmtFromStream(ModuleFile &F) {
       break;
 
     case EXPR_GENERIC_SELECTION:
-      S = new (Context) GenericSelectionExpr(Empty);
+      S = GenericSelectionExpr::CreateEmpty(
+          Context,
+          /*NumAssocs=*/Record[ASTStmtReader::NumExprFields]);
       break;
 
     case EXPR_OBJC_STRING_LITERAL:
diff --git a/clang/lib/Serialization/ASTWriterStmt.cpp b/clang/lib/Serialization/ASTWriterStmt.cpp
index 582d9933a0c..4f7b492d024 100644
--- a/clang/lib/Serialization/ASTWriterStmt.cpp
+++ b/clang/lib/Serialization/ASTWriterStmt.cpp
@@ -968,18 +968,24 @@ void ASTStmtWriter::VisitBlockExpr(BlockExpr *E) {
 
 void ASTStmtWriter::VisitGenericSelectionExpr(GenericSelectionExpr *E) {
   VisitExpr(E);
+
   Record.push_back(E->getNumAssocs());
   Record.push_back(E->ResultIndex);
-
-  Record.AddStmt(E->getControllingExpr());
-  for (unsigned I = 0, N = E->getNumAssocs(); I != N; ++I) {
-    Record.AddTypeSourceInfo(E->getAssocTypeSourceInfo(I));
-    Record.AddStmt(E->getAssocExpr(I));
-  }
-
   Record.AddSourceLocation(E->getGenericLoc());
   Record.AddSourceLocation(E->getDefaultLoc());
   Record.AddSourceLocation(E->getRParenLoc());
+
+  Stmt **Stmts = E->getTrailingObjects<Stmt *>();
+  // Add 1 to account for the controlling expression which is the first
+  // expression in the trailing array of Stmt *. This is not needed for
+  // the trailing array of TypeSourceInfo *.
+  for (unsigned I = 0, N = E->getNumAssocs() + 1; I < N; ++I)
+    Record.AddStmt(Stmts[I]);
+
+  TypeSourceInfo **TSIs = E->getTrailingObjects<TypeSourceInfo *>();
+  for (unsigned I = 0, N = E->getNumAssocs(); I < N; ++I)
+    Record.AddTypeSourceInfo(TSIs[I]);
+
   Code = serialization::EXPR_GENERIC_SELECTION;
 }