[llvm] r218726 - Implement DW_TAG_subrange_type with DW_AT_count rather than DW_AT_upper_bound
David Blaikie
dblaikie at gmail.com
Tue Sep 30 17:56:55 PDT 2014
Author: dblaikie
Date: Tue Sep 30 19:56:55 2014
New Revision: 218726
URL: http://llvm.org/viewvc/llvm-project?rev=218726&view=rev
Log:
Implement DW_TAG_subrange_type with DW_AT_count rather than DW_AT_upper_bound
This allows proper disambiguation of unbounded arrays and arrays of zero
bound ("struct foo { int x[]; };" and "struct foo { int x[0]; }"). GCC
instead produces an upper bound of -1 in the latter situation, but count
seems tidier. This way lower_bound is provided if it's not the language
default and count is provided if the count is known, otherwise it's
omitted. Simple.
If someone wants to look at rdar://problem/12566646 and see if this
change is acceptable to that bug/fix, that might be helpful (see the
empty-and-one-elem-array.ll test case which cites that radar).
Modified:
llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
llvm/trunk/test/DebugInfo/X86/dbg-subrange.ll
llvm/trunk/test/DebugInfo/X86/empty-and-one-elem-array.ll
llvm/trunk/test/DebugInfo/X86/nondefault-subrange-array.ll
Modified: llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp?rev=218726&r1=218725&r2=218726&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp (original)
+++ llvm/trunk/lib/CodeGen/AsmPrinter/DwarfUnit.cpp Tue Sep 30 19:56:55 2014
@@ -1748,9 +1748,7 @@ void DwarfUnit::constructSubrangeDIE(DIE
// The LowerBound value defines the lower bounds which is typically zero for
// C/C++. The Count value is the number of elements. Values are 64 bit. If
// Count == -1 then the array is unbounded and we do not emit
- // DW_AT_lower_bound and DW_AT_upper_bound attributes. If LowerBound == 0 and
- // Count == 0, then the array has zero elements in which case we do not emit
- // an upper bound.
+ // DW_AT_lower_bound and DW_AT_count attributes.
int64_t LowerBound = SR.getLo();
int64_t DefaultLowerBound = getDefaultLowerBound();
int64_t Count = SR.getCount();
@@ -1758,11 +1756,10 @@ void DwarfUnit::constructSubrangeDIE(DIE
if (DefaultLowerBound == -1 || LowerBound != DefaultLowerBound)
addUInt(DW_Subrange, dwarf::DW_AT_lower_bound, None, LowerBound);
- if (Count != -1 && Count != 0)
+ if (Count != -1)
// FIXME: An unbounded array should reference the expression that defines
// the array.
- addUInt(DW_Subrange, dwarf::DW_AT_upper_bound, None,
- LowerBound + Count - 1);
+ addUInt(DW_Subrange, dwarf::DW_AT_count, None, Count);
}
/// constructArrayTypeDIE - Construct array type DIE from DICompositeType.
Modified: llvm/trunk/test/DebugInfo/X86/dbg-subrange.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/dbg-subrange.ll?rev=218726&r1=218725&r2=218726&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/dbg-subrange.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/dbg-subrange.ll Tue Sep 30 19:56:55 2014
@@ -4,7 +4,7 @@ target datalayout = "e-p:64:64:64-i1:8:8
target triple = "x86_64-apple-macosx10.7.2"
@s = common global [4294967296 x i8] zeroinitializer, align 16
-;CHECK: .long 4294967295
+; CHECK: .quad 4294967296 ## DW_AT_count
define void @bar() nounwind uwtable ssp {
entry:
Modified: llvm/trunk/test/DebugInfo/X86/empty-and-one-elem-array.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/empty-and-one-elem-array.ll?rev=218726&r1=218725&r2=218726&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/empty-and-one-elem-array.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/empty-and-one-elem-array.ll Tue Sep 30 19:56:55 2014
@@ -25,9 +25,6 @@ entry:
declare void @llvm.dbg.declare(metadata, metadata) nounwind readnone
-; An empty array should not have an AT_upper_bound attribute. But an array of 1
-; should.
-
; CHECK: DW_TAG_base_type
; CHECK-NEXT: DW_AT_name [DW_FORM_strp] ( .debug_str[{{.*}}] = "int")
; CHECK-NEXT: DW_AT_encoding [DW_FORM_data1] (DW_ATE_signed)
@@ -46,7 +43,7 @@ declare void @llvm.dbg.declare(metadata,
; CHECK-NEXT: DW_AT_type [DW_FORM_ref4]
; CHECK: DW_TAG_subrange_type [{{.*}}]
; CHECK-NEXT: DW_AT_type [DW_FORM_ref4]
-; CHECK-NEXT: DW_AT_upper_bound [DW_FORM_data1] (0x00)
+; CHECK-NEXT: DW_AT_count [DW_FORM_data1] (0x01)
; int bar::b[0]:
; CHECK: DW_TAG_structure_type
@@ -59,9 +56,9 @@ declare void @llvm.dbg.declare(metadata,
; int[0]:
; CHECK: DW_TAG_array_type [{{.*}}] *
; CHECK-NEXT: DW_AT_type [DW_FORM_ref4]
-; CHECK: DW_TAG_subrange_type [11]
+; CHECK: DW_TAG_subrange_type
; CHECK-NEXT: DW_AT_type [DW_FORM_ref4]
-; CHECK-NOT: DW_AT_upper_bound
+; CHECK: DW_AT_count [DW_FORM_data1] (0x00)
!llvm.dbg.cu = !{!0}
!llvm.module.flags = !{!33}
Modified: llvm/trunk/test/DebugInfo/X86/nondefault-subrange-array.ll
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/test/DebugInfo/X86/nondefault-subrange-array.ll?rev=218726&r1=218725&r2=218726&view=diff
==============================================================================
--- llvm/trunk/test/DebugInfo/X86/nondefault-subrange-array.ll (original)
+++ llvm/trunk/test/DebugInfo/X86/nondefault-subrange-array.ll Tue Sep 30 19:56:55 2014
@@ -19,7 +19,7 @@
; CHECK: DW_TAG_subrange_type
; CHECK-NEXT: DW_AT_type [DW_FORM_ref4] (cu + 0x{{[0-9a-f]*}} => {[[BASE2:0x[0-9a-f]*]]})
; CHECK-NEXT: DW_AT_lower_bound [DW_FORM_data8] (0xfffffffffffffffd)
-; CHECK-NEXT: DW_AT_upper_bound [DW_FORM_data1] (0x26)
+; CHECK-NEXT: DW_AT_count [DW_FORM_data1] (0x2a)
; CHECK: [[BASE]]: DW_TAG_base_type
; CHECK: [[BASE2]]: DW_TAG_base_type
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