[AST] Only store the needed data in SwitchStmt

Don't store the data for the init statement and condition variable
if not needed. This cuts the size of SwitchStmt by up to 2 pointers.
The order of the children is intentionally kept the same.

Also use the newly available space in the bit-fields of Stmt
to store the bit representing whether all enums have been covered
instead of using a PointerIntPair.

Differential Revision: https://reviews.llvm.org/D53714

Reviewed By: rjmccall

llvm-svn: 345510

1 files changed, 13 insertions, 3 deletions

diff --git a/clang/lib/Serialization/ASTWriterStmt.cpp b/clang/lib/Serialization/ASTWriterStmt.cpp
index e7f9f35dcc2..396cc1c2d05 100644
--- a/clang/lib/Serialization/ASTWriterStmt.cpp
+++ b/clang/lib/Serialization/ASTWriterStmt.cpp
@@ -159,12 +159,22 @@ void ASTStmtWriter::VisitIfStmt(IfStmt *S) {
 
 void ASTStmtWriter::VisitSwitchStmt(SwitchStmt *S) {
   VisitStmt(S);
-  Record.AddStmt(S->getInit());
-  Record.AddDeclRef(S->getConditionVariable());
+
+  bool HasInit = S->getInit() != nullptr;
+  bool HasVar = S->getConditionVariableDeclStmt() != nullptr;
+  Record.push_back(HasInit);
+  Record.push_back(HasVar);
+  Record.push_back(S->isAllEnumCasesCovered());
+
   Record.AddStmt(S->getCond());
   Record.AddStmt(S->getBody());
+  if (HasInit)
+    Record.AddStmt(S->getInit());
+  if (HasVar)
+    Record.AddDeclRef(S->getConditionVariable());
+
   Record.AddSourceLocation(S->getSwitchLoc());
-  Record.push_back(S->isAllEnumCasesCovered());
+
   for (SwitchCase *SC = S->getSwitchCaseList(); SC;
        SC = SC->getNextSwitchCase())
     Record.push_back(Writer.RecordSwitchCaseID(SC));