Use the 'count' attribute instead of the 'upper_bound' attribute.

If we have a type 'int a[1]' and a type 'int b[0]', the generated DWARF is the
same for both of them because we use the 'upper_bound' attribute. Instead use
the 'count' attrbute, which gives the correct number of elements in the array.
<rdar://problem/12566646>


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@167807 91177308-0d34-0410-b5e6-96231b3b80d8

lib/CodeGen/CGDebugInfo.cpp

@@ -1473,23 +1473,23 @@ llvm::DIType CGDebugInfo::CreateType(const ObjCInterfaceType *Ty,
 
 llvm::DIType CGDebugInfo::CreateType(const VectorType *Ty, llvm::DIFile Unit) {
   llvm::DIType ElementTy = getOrCreateType(Ty->getElementType(), Unit);
-  int64_t NumElems = Ty->getNumElements();
+  int64_t UpperBound = Ty->getNumElements();
   int64_t LowerBound = 0;
-  if (NumElems == 0)
+  if (UpperBound == 0)
     // If number of elements are not known then this is an unbounded array.
     // Use Low = 1, Hi = 0 to express such arrays.
     LowerBound = 1;
   else
-    --NumElems;
+    --UpperBound;
 
-  llvm::Value *Subscript = DBuilder.getOrCreateSubrange(LowerBound, NumElems);
+  llvm::Value *Subscript = DBuilder.getOrCreateSubrange(LowerBound, UpperBound,
+                                                        Ty->getNumElements());
   llvm::DIArray SubscriptArray = DBuilder.getOrCreateArray(Subscript);
 
   uint64_t Size = CGM.getContext().getTypeSize(Ty);
   uint64_t Align = CGM.getContext().getTypeAlign(Ty);
 
-  return
-    DBuilder.createVectorType(Size, Align, ElementTy, SubscriptArray);
+  return DBuilder.createVectorType(Size, Align, ElementTy, SubscriptArray);
 }
 
 llvm::DIType CGDebugInfo::CreateType(const ArrayType *Ty,
@@ -1525,17 +1525,20 @@ llvm::DIType CGDebugInfo::CreateType(const ArrayType *Ty,
   while ((Ty = dyn_cast<ArrayType>(EltTy))) {
     int64_t UpperBound = 0;
     int64_t LowerBound = 0;
+    uint64_t Count = 0;
     if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(Ty)) {
-      if (CAT->getSize().getZExtValue())
-        UpperBound = CAT->getSize().getZExtValue() - 1;
+      Count = CAT->getSize().getZExtValue();
+      if (Count)
+        UpperBound = Count - 1;
     } else
       // This is an unbounded array. Use Low = 1, Hi = 0 to express such 
       // arrays.
       LowerBound = 1;
 
     // FIXME: Verify this is right for VLAs.
     Subscripts.push_back(DBuilder.getOrCreateSubrange(LowerBound,
-                                                      UpperBound));
+                                                      UpperBound,
+                                                      Count));
     EltTy = Ty->getElementType();
   }
 

test/CodeGen/debug-info-zero-length-arrays.c

@@ -0,0 +1,33 @@
+// RUN: %clang -emit-llvm -S -g %s -o - | FileCheck %s
+
+// <rdar://problem/12566646>
+
+// The subrange for a type 'int[1]' and 'int[0]' should be different. Use the
+// 'count' attribute instead of the 'upper_bound' attribute do disabmiguate the
+// DIE.
+
+struct foo {
+  int a;
+  int b[1];
+};
+
+struct bar {
+  int a;
+  int b[0];
+};
+
+int main()
+{
+  struct foo my_foo;
+  struct bar my_bar;
+
+  my_foo.a = 3;
+  my_bar.a = 5;
+
+  return my_foo.a + my_bar.a;
+}
+
+// The third metadata operand is the count.
+//
+// CHECK: metadata !{i32 786465, i64 0, i64 0, i64 1} ; [ DW_TAG_subrange_type ]
+// CHECK: metadata !{i32 786465, i64 0, i64 0, i64 0} ; [ DW_TAG_subrange_type ]

test/CodeGenCXX/debug-info-flex-member.cpp

@@ -1,6 +1,6 @@
 // RUN: %clang_cc1 -emit-llvm -g -triple x86_64-apple-darwin %s -o - | FileCheck %s
 
-// CHECK: metadata !{i32 {{.*}}, i64 1, i64 0}        ; [ DW_TAG_subrange_type ]
+// CHECK: metadata !{i32 {{.*}}, i64 1, i64 0, i64 0} ; [ DW_TAG_subrange_type ]
 
 struct StructName {
   int member[];