When in a limited debug information situation if we can find the original

declaration for the type then go ahead and use that, it's still smaller
than creating an all new derived type.

Part of rdar://10335756 and others.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@146779 91177308-0d34-0410-b5e6-96231b3b80d8

3 files changed, 30 insertions, 9 deletions

diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index dd76640ba3..af6d25d363 100644
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -488,6 +488,11 @@ llvm::DIType CGDebugInfo::CreatePointeeType(QualType PointeeTy,
 
   // Limit debug info for the pointee type.
 
+  // If we have an existing type, use that, it's still smaller than creating
+  // a new type.
+  llvm::DIType Ty = getTypeOrNull(PointeeTy);
+  if (Ty.Verify()) return Ty;
+
   // Handle qualifiers.
   if (PointeeTy.hasLocalQualifiers())
     return CreateQualifiedType(PointeeTy, Unit);
@@ -1565,15 +1570,12 @@ static QualType UnwrapTypeForDebugInfo(QualType T) {
   return T;
 }
 
-/// getOrCreateType - Get the type from the cache or create a new
-/// one if necessary.
-llvm::DIType CGDebugInfo::getOrCreateType(QualType Ty, llvm::DIFile Unit) {
-  if (Ty.isNull())
-    return llvm::DIType();
+/// getType - Get the type from the cache or return null type if it doesn't exist.
+llvm::DIType CGDebugInfo::getTypeOrNull(QualType Ty) {
 
   // Unwrap the type as needed for debug information.
   Ty = UnwrapTypeForDebugInfo(Ty);
-
+  
   // Check for existing entry.
   llvm::DenseMap<void *, llvm::WeakVH>::iterator it =
     TypeCache.find(Ty.getAsOpaquePtr());
@@ -1583,6 +1585,21 @@ llvm::DIType CGDebugInfo::getOrCreateType(QualType Ty, llvm::DIFile Unit) {
       return llvm::DIType(cast<llvm::MDNode>(it->second));
   }
 
+  return llvm::DIType();
+}
+
+/// getOrCreateType - Get the type from the cache or create a new
+/// one if necessary.
+llvm::DIType CGDebugInfo::getOrCreateType(QualType Ty, llvm::DIFile Unit) {
+  if (Ty.isNull())
+    return llvm::DIType();
+
+  // Unwrap the type as needed for debug information.
+  Ty = UnwrapTypeForDebugInfo(Ty);
+  
+  llvm::DIType T = getTypeOrNull(Ty);
+  if (T.Verify()) return T;
+
   // Otherwise create the type.
   llvm::DIType Res = CreateTypeNode(Ty, Unit);
 
diff --git a/lib/CodeGen/CGDebugInfo.h b/lib/CodeGen/CGDebugInfo.h
index 087cdd08a4..8831c535fa 100644
--- a/lib/CodeGen/CGDebugInfo.h
+++ b/lib/CodeGen/CGDebugInfo.h
@@ -93,6 +93,7 @@ class CGDebugInfo {
   llvm::DIType CreateType(const MemberPointerType *Ty, llvm::DIFile F);
   llvm::DIType CreateType(const AtomicType *Ty, llvm::DIFile F);
   llvm::DIType CreateEnumType(const EnumDecl *ED);
+  llvm::DIType getTypeOrNull(const QualType);
   llvm::DIType getOrCreateMethodType(const CXXMethodDecl *Method,
                                      llvm::DIFile F);
   llvm::DIType getOrCreateFunctionType(const Decl *D, QualType FnType,
diff --git a/test/CodeGenCXX/debug-info-fwd-ref.cpp b/test/CodeGenCXX/debug-info-fwd-ref.cpp
index e01733c777..4946815458 100644
--- a/test/CodeGenCXX/debug-info-fwd-ref.cpp
+++ b/test/CodeGenCXX/debug-info-fwd-ref.cpp
@@ -16,8 +16,11 @@ int main(int argc, char** argv) {
     return 0;
 }
 
-// Make sure we have two DW_TAG_class_types for baz and bar for their forward
+// Make sure we have two DW_TAG_class_types for baz and bar and no forward
 // references.
 // FIXME: These should be struct types to match the declaration.
-// CHECK: !17 = metadata !{i32 720898, null, metadata !"baz", metadata !6, i32 3, i64 0, i64 0, i32 0, i32 4, null, null, i32 0, null, null} ; [ DW_TAG_class_type ]
-// CHECK: !26 = metadata !{i32 720898, null, metadata !"bar", metadata !6, i32 8, i64 0, i64 0, i32 0, i32 4, null, null, i32 0, null, null} ; [ DW_TAG_class_type ]
+// CHECK: metadata !{i32 720898, null, metadata !"bar", metadata !6, i32 8, i64 128, i64 64, i32 0, i32 0, null, metadata !7, i32 0, null, null} ; [ DW_TAG_class_type ]
+// CHECK: metadata !{i32 720898, null, metadata !"baz", metadata !6, i32 3, i64 32, i64 32, i32 0, i32 0, null, metadata !10, i32 0, null, null} ; [ DW_TAG_class_type ]
+// CHECK-NOT: metadata !{i32 720915, null, metadata !"bar", metadata !6, i32 9, i64 0, i64 0, i32 0, i32 4, i32 0, null, i32 0, i32 0} ; [ DW_TAG_class_type ]
+// CHECK-NOT: metadata !{i32 720898, null, metadata !"baz", metadata !6, i32 3, i64 0, i64 0, i32 0, i32 4, null, null, i32 0, null, null} ; [ DW_TAG_class_type ]
+