DebugInfo: support for DW_TAG_atomic_type

[vleschuk]

Summary

Mark C11 _Atomic variables with DW_TAG_atomic_type tag.

This is the simplest way to achieve the goal: modifying Qualifiers results in much more changes and putting emission of tag into CreateQualifiedType() along with DW_TAG_const_type and friends seems more logic but requires way more changes and could break something else (my first attempt to add atomic to qualifiers resulted in lots of failures in OpenCL tests for some reason).

[aprantl]

LGTM with inline comments addressed.

test/CodeGen/debug-info-atomic.c

4

Why do we need the const here?

5

Can you check that it is actually the DIVariable "i" that has the atomic type?

[vleschuk]

test/CodeGen/debug-info-atomic.c

4

I thought it would be better to make sure that "enabling" atomic doesn't affect other qualifiers.

[vleschuk]

Made test more strict: it now checks that variable i is atomic.

[aprantl]

One more inline comment.

test/CodeGen/debug-info-atomic.c

4

Please use FileCheck variables ![[TYPE:[0-9]+]] instead of hardcoding the numbers. This is bound to break soon otherwise.

lib/CodeGen/CGDebugInfo.cpp

llvm::DIType *CGDebugInfo::CreateType(const MemberPointerType *Ty,
   return DBuilder.createMemberPointerType(
       getOrCreateInstanceMethodType(CGM.getContext().getPointerType(QualType(
                                         Ty->getClass(), FPT->getTypeQuals())),
                                     FPT, U),
       ClassType, Size, /*Align=*/0, Flags);
 }
 
 llvm::DIType *CGDebugInfo::CreateType(const AtomicType *Ty, llvm::DIFile *U) {
-  // Ignore the atomic wrapping
-  // FIXME: What is the correct representation?
-  return getOrCreateType(Ty->getValueType(), U);
+  auto *FromTy = getOrCreateType(Ty->getValueType(), U);
+  return DBuilder.createQualifiedType(llvm::dwarf::DW_TAG_atomic_type, FromTy);
 }
 
 llvm::DIType* CGDebugInfo::CreateType(const PipeType *Ty,
                                      llvm::DIFile *U) {
   return getOrCreateType(Ty->getElementType(), U);
 }
 
 llvm::DIType *CGDebugInfo::CreateEnumType(const EnumType *Ty) {

test/CodeGen/debug-info-atomic.c

+// RUN: %clang -g -c -std=c11 -S -emit-llvm -o - %s | FileCheck %s
+
+// CHECK: !DIGlobalVariable(name: "i"{{.*}}type: !5, isLocal: false, isDefinition: true)
+// CHECK: !5 = !DIDerivedType(tag: DW_TAG_const_type, baseType: !6)
+// CHECK: !6 = !DIDerivedType(tag: DW_TAG_atomic_type, baseType: !7)
+// CHECK: !7 = !DIBasicType(name: "int", size: 32, encoding: DW_ATE_signed)
+_Atomic const int i;