PR14759: Improve/correct support for debug info for C++ member pointers.

Using added LLVM functionality in r171698. This works in GDB for member
variable pointers but not member function pointers. See the LLVM commit and
GDB bug 14998 for details.

Un-xfailing cases in the GDB 7.5 test suite will follow.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@171699 91177308-0d34-0410-b5e6-96231b3b80d8

2 files changed, 7 insertions, 32 deletions

diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index bc715f4d6d..4ebce65ff4 100644
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/lib/CodeGen/CGDebugInfo.cpp
@@ -1589,38 +1589,8 @@ llvm::DIType CGDebugInfo::CreateType(const RValueReferenceType *Ty,
 
 llvm::DIType CGDebugInfo::CreateType(const MemberPointerType *Ty, 
                                      llvm::DIFile U) {
-  QualType PointerDiffTy = CGM.getContext().getPointerDiffType();
-  llvm::DIType PointerDiffDITy = getOrCreateType(PointerDiffTy, U);
-  
-  if (!Ty->getPointeeType()->isFunctionType()) {
-    // We have a data member pointer type.
-    return PointerDiffDITy;
-  }
-  
-  // We have a member function pointer type. Treat it as a struct with two
-  // ptrdiff_t members.
-  std::pair<uint64_t, unsigned> Info = CGM.getContext().getTypeInfo(Ty);
-
-  uint64_t FieldOffset = 0;
-  llvm::Value *ElementTypes[2];
-  
-  // FIXME: This should be a DW_TAG_pointer_to_member type.
-  ElementTypes[0] =
-    DBuilder.createMemberType(U, "ptr", U, 0,
-                              Info.first, Info.second, FieldOffset, 0,
-                              PointerDiffDITy);
-  FieldOffset += Info.first;
-  
-  ElementTypes[1] =
-    DBuilder.createMemberType(U, "ptr", U, 0,
-                              Info.first, Info.second, FieldOffset, 0,
-                              PointerDiffDITy);
-  
-  llvm::DIArray Elements = DBuilder.getOrCreateArray(ElementTypes);
-
-  return DBuilder.createStructType(U, StringRef("test"), 
-                                   U, 0, FieldOffset, 
-                                   0, 0, Elements);
+  return DBuilder.createMemberPointerType(CreatePointeeType(Ty->getPointeeType(), U),
+                                    getOrCreateType(QualType(Ty->getClass(), 0), U));
 }
 
 llvm::DIType CGDebugInfo::CreateType(const AtomicType *Ty, 
diff --git a/test/CodeGenCXX/debug-info-method.cpp b/test/CodeGenCXX/debug-info-method.cpp
index dfd397987f..e9aa34a4a0 100644
--- a/test/CodeGenCXX/debug-info-method.cpp
+++ b/test/CodeGenCXX/debug-info-method.cpp
@@ -1,5 +1,7 @@
 // RUN: %clang_cc1 -emit-llvm -std=c++11 -g %s -o - | FileCheck %s
 // CHECK: metadata !"_ZN1A3fooEiS_3$_0", {{.*}} [protected]
+// CHECK: DW_TAG_ptr_to_member_type
+// CHECK: DW_TAG_ptr_to_member_type
 // CHECK: ""{{.*}}DW_TAG_arg_variable
 // CHECK: ""{{.*}}DW_TAG_arg_variable
 // CHECK: ""{{.*}}DW_TAG_arg_variable
@@ -17,3 +19,6 @@ void A::foo(int, A, decltype(u)) {
 }
 
 A a;
+
+int A::*x = 0;
+int (A::*y)(int) = 0;