[CodeView] Reserve TypeDatabase records up front.

Most of the time we know exactly how many type records we
have in a list, and we want to use the visitor to deserialize
them into actual records in a database.  Previously we were
just using push_back() every time without reserving the space
up front in the vector.  This is obviously terrible from a
performance standpoint, and it's not uncommon to have PDB
files with half a million type records, where the performance
degredation was quite noticeable.

llvm-svn: 302302

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/include/llvm/DebugInfo/CodeView/TypeDatabase.h b/llvm/include/llvm/DebugInfo/CodeView/TypeDatabase.h
index 220de4bf0ee..be7b19e7df0 100644
--- a/llvm/include/llvm/DebugInfo/CodeView/TypeDatabase.h
+++ b/llvm/include/llvm/DebugInfo/CodeView/TypeDatabase.h
@@ -21,7 +21,7 @@ namespace llvm {
 namespace codeview {
 class TypeDatabase {
 public:
-  TypeDatabase() : TypeNameStorage(Allocator) {}
+  explicit TypeDatabase(uint32_t ExpectedSize);
 
   /// Gets the type index for the next type record.
   TypeIndex getNextTypeIndex() const;