ASTWriter: Cache some DenseMaps we use repeatedly.

 - This reduces our total # of allocations building a PCH for Cocoa.h by almost
   a whopping 50%.
 - A SmallPtrMap would be cleaner, but since we don't have one yet...

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@151697 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 4 insertions, 5 deletions

diff --git a/lib/Serialization/ASTWriterStmt.cpp b/lib/Serialization/ASTWriterStmt.cpp
index 4f766d9b92..22fdfe162a 100644
--- a/lib/Serialization/ASTWriterStmt.cpp
+++ b/lib/Serialization/ASTWriterStmt.cpp
@@ -1586,11 +1586,10 @@ void ASTWriter::WriteSubStmt(Stmt *S,
 void ASTWriter::FlushStmts() {
   RecordData Record;
 
-  /// \brief Set of parent Stmts for the currently serializing sub stmt.
-  llvm::DenseSet<Stmt *> ParentStmts;
-  /// \brief Offsets of sub stmts already serialized. The offset points
-  /// just after the stmt record.
-  llvm::DenseMap<Stmt *, uint64_t> SubStmtEntries;
+  // We expect to be the only consumer of the two temporary statement maps,
+  // assert that they are empty.
+  assert(SubStmtEntries.empty() && "unexpected entries in sub stmt map");
+  assert(ParentStmts.empty() && "unexpected entries in parent stmt map");
 
   for (unsigned I = 0, N = StmtsToEmit.size(); I != N; ++I) {
     WriteSubStmt(StmtsToEmit[I], SubStmtEntries, ParentStmts);