From d448c732cb50091866bfa1e08aaa0a59f3c03188 Mon Sep 17 00:00:00 2001
From: Zachary Turner <zturner@google.com>
Date: Wed, 24 May 2017 00:26:27 +0000
Subject: [PATCH] Don't do a full scan of the type stream before processing
 records.

LazyRandomTypeCollection is designed for random access, and in
order to provide this it lazily indexes ranges of types.  In the
case of types from an object file, there is no partial index
to build off of, so it has to index the full stream up front.
However, merging types only requires sequential access, and when
that is needed, this extra work is simply wasted.  Changing the
algorithm to work on sequential arrays of types rather than
random access type collections eliminates this up front scan.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@303707 91177308-0d34-0410-b5e6-96231b3b80d8
---
 .../DebugInfo/CodeView/TypeStreamMerger.h     |  6 ++---
 lib/DebugInfo/CodeView/TypeStreamMerger.cpp   | 22 +++++++++----------
 2 files changed, 14 insertions(+), 14 deletions(-)

diff --git a/include/llvm/DebugInfo/CodeView/TypeStreamMerger.h b/include/llvm/DebugInfo/CodeView/TypeStreamMerger.h
index d914cf2fd9f..3ad2b4e9c92 100644
--- a/include/llvm/DebugInfo/CodeView/TypeStreamMerger.h
+++ b/include/llvm/DebugInfo/CodeView/TypeStreamMerger.h
@@ -40,7 +40,7 @@ class TypeTableBuilder;
 /// appropriate error code.
 Error mergeTypeRecords(TypeTableBuilder &Dest,
                        SmallVectorImpl<TypeIndex> &SourceToDest,
-                       TypeServerHandler *Handler, TypeCollection &Types);
+                       TypeServerHandler *Handler, const CVTypeArray &Types);
 
 /// \brief Merge one set of id records into another.  This method assumes
 /// that all records are id records, and there are no Type records present.
@@ -65,7 +65,7 @@ Error mergeTypeRecords(TypeTableBuilder &Dest,
 /// appropriate error code.
 Error mergeIdRecords(TypeTableBuilder &Dest, ArrayRef<TypeIndex> Types,
                      SmallVectorImpl<TypeIndex> &SourceToDest,
-                     TypeCollection &Ids);
+  const CVTypeArray &Ids);
 
 /// \brief Merge a unified set of type and id records, splitting them into
 /// separate output streams.
@@ -89,7 +89,7 @@ Error mergeTypeAndIdRecords(TypeTableBuilder &DestIds,
                             TypeTableBuilder &DestTypes,
                             SmallVectorImpl<TypeIndex> &SourceToDest,
                             TypeServerHandler *Handler,
-                            TypeCollection &IdsAndTypes);
+  const CVTypeArray &IdsAndTypes);
 
 } // end namespace codeview
 } // end namespace llvm
diff --git a/lib/DebugInfo/CodeView/TypeStreamMerger.cpp b/lib/DebugInfo/CodeView/TypeStreamMerger.cpp
index 152634056bd..383799bca7e 100644
--- a/lib/DebugInfo/CodeView/TypeStreamMerger.cpp
+++ b/lib/DebugInfo/CodeView/TypeStreamMerger.cpp
@@ -81,14 +81,14 @@ public:
   Error visitMemberEnd(CVMemberRecord &Record) override;
 
   Error mergeTypesAndIds(TypeTableBuilder &DestIds, TypeTableBuilder &DestTypes,
-                         TypeCollection &IdsAndTypes);
+    const CVTypeArray &IdsAndTypes);
   Error mergeIdRecords(TypeTableBuilder &Dest,
                        ArrayRef<TypeIndex> TypeSourceToDest,
-                       TypeCollection &Ids);
-  Error mergeTypeRecords(TypeTableBuilder &Dest, TypeCollection &Types);
+    const CVTypeArray &Ids);
+  Error mergeTypeRecords(TypeTableBuilder &Dest, const CVTypeArray &Types);
 
 private:
-  Error doit(TypeCollection &Types);
+  Error doit(const CVTypeArray &Types);
 
   void addMapping(TypeIndex Idx);
 
@@ -497,7 +497,7 @@ Error TypeStreamMerger::visitUnknownType(CVType &Rec) {
 }
 
 Error TypeStreamMerger::mergeTypeRecords(TypeTableBuilder &Dest,
-                                         TypeCollection &Types) {
+  const CVTypeArray &Types) {
   DestTypeStream = &Dest;
 
   return doit(Types);
@@ -505,7 +505,7 @@ Error TypeStreamMerger::mergeTypeRecords(TypeTableBuilder &Dest,
 
 Error TypeStreamMerger::mergeIdRecords(TypeTableBuilder &Dest,
                                        ArrayRef<TypeIndex> TypeSourceToDest,
-                                       TypeCollection &Ids) {
+  const CVTypeArray &Ids) {
   DestIdStream = &Dest;
   TypeLookup = TypeSourceToDest;
 
@@ -514,14 +514,14 @@ Error TypeStreamMerger::mergeIdRecords(TypeTableBuilder &Dest,
 
 Error TypeStreamMerger::mergeTypesAndIds(TypeTableBuilder &DestIds,
                                          TypeTableBuilder &DestTypes,
-                                         TypeCollection &IdsAndTypes) {
+  const CVTypeArray &IdsAndTypes) {
   DestIdStream = &DestIds;
   DestTypeStream = &DestTypes;
 
   return doit(IdsAndTypes);
 }
 
-Error TypeStreamMerger::doit(TypeCollection &Types) {
+Error TypeStreamMerger::doit(const CVTypeArray &Types) {
   LastError = Error::success();
 
   if (auto EC = codeview::visitTypeStream(Types, *this, Handler))
@@ -559,7 +559,7 @@ Error TypeStreamMerger::doit(TypeCollection &Types) {
 Error llvm::codeview::mergeTypeRecords(TypeTableBuilder &Dest,
                                        SmallVectorImpl<TypeIndex> &SourceToDest,
                                        TypeServerHandler *Handler,
-                                       TypeCollection &Types) {
+  const CVTypeArray &Types) {
   TypeStreamMerger M(SourceToDest, Handler);
   return M.mergeTypeRecords(Dest, Types);
 }
@@ -567,7 +567,7 @@ Error llvm::codeview::mergeTypeRecords(TypeTableBuilder &Dest,
 Error llvm::codeview::mergeIdRecords(TypeTableBuilder &Dest,
                                      ArrayRef<TypeIndex> TypeSourceToDest,
                                      SmallVectorImpl<TypeIndex> &SourceToDest,
-                                     TypeCollection &Ids) {
+  const CVTypeArray &Ids) {
   TypeStreamMerger M(SourceToDest, nullptr);
   return M.mergeIdRecords(Dest, TypeSourceToDest, Ids);
 }
@@ -575,7 +575,7 @@ Error llvm::codeview::mergeIdRecords(TypeTableBuilder &Dest,
 Error llvm::codeview::mergeTypeAndIdRecords(
     TypeTableBuilder &DestIds, TypeTableBuilder &DestTypes,
     SmallVectorImpl<TypeIndex> &SourceToDest, TypeServerHandler *Handler,
-    TypeCollection &IdsAndTypes) {
+  const CVTypeArray &IdsAndTypes) {
 
   TypeStreamMerger M(SourceToDest, Handler);
   return M.mergeTypesAndIds(DestIds, DestTypes, IdsAndTypes);
-- 
2.40.0