[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, 5 insertions, 0 deletions

diff --git a/llvm/lib/DebugInfo/CodeView/TypeDatabase.cpp b/llvm/lib/DebugInfo/CodeView/TypeDatabase.cpp
index efaba4646ff..5b8841041f8 100644
--- a/llvm/lib/DebugInfo/CodeView/TypeDatabase.cpp
+++ b/llvm/lib/DebugInfo/CodeView/TypeDatabase.cpp
@@ -65,6 +65,11 @@ static const SimpleTypeEntry SimpleTypeNames[] = {
     {"__bool64*", SimpleTypeKind::Boolean64},
 };
 
+TypeDatabase::TypeDatabase(uint32_t ExpectedSize) : TypeNameStorage(Allocator) {
+  CVUDTNames.reserve(ExpectedSize);
+  TypeRecords.reserve(ExpectedSize);
+}
+
 /// Gets the type index for the next type record.
 TypeIndex TypeDatabase::getNextTypeIndex() const {
   return TypeIndex(TypeIndex::FirstNonSimpleIndex + CVUDTNames.size());