From 30305bec25cac981c6d4a3b8be004401310a82a7 Mon Sep 17 00:00:00 2001
From: Bill Wendling <isanbard@gmail.com>
Date: Tue, 13 Nov 2012 02:31:58 +0000
Subject: [PATCH] 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                  | 21 +++++++------
 test/CodeGen/debug-info-zero-length-arrays.c | 33 ++++++++++++++++++++
 test/CodeGenCXX/debug-info-flex-member.cpp   |  2 +-
 3 files changed, 46 insertions(+), 10 deletions(-)
 create mode 100644 test/CodeGen/debug-info-zero-length-arrays.c

diff --git a/lib/CodeGen/CGDebugInfo.cpp b/lib/CodeGen/CGDebugInfo.cpp
index 80fa09be74..3843889635 100644
--- a/lib/CodeGen/CGDebugInfo.cpp
+++ b/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,
@@ -1525,9 +1525,11 @@ 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.
@@ -1535,7 +1537,8 @@ llvm::DIType CGDebugInfo::CreateType(const ArrayType *Ty,
     
     // FIXME: Verify this is right for VLAs.
     Subscripts.push_back(DBuilder.getOrCreateSubrange(LowerBound,
-                                                      UpperBound));
+                                                      UpperBound,
+                                                      Count));
     EltTy = Ty->getElementType();
   }
 
diff --git a/test/CodeGen/debug-info-zero-length-arrays.c b/test/CodeGen/debug-info-zero-length-arrays.c
new file mode 100644
index 0000000000..68f7c016ff
--- /dev/null
+++ b/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 ]
diff --git a/test/CodeGenCXX/debug-info-flex-member.cpp b/test/CodeGenCXX/debug-info-flex-member.cpp
index b6aa6dac6b..72a5bf8461 100644
--- a/test/CodeGenCXX/debug-info-flex-member.cpp
+++ b/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[];