Hi!
As the attached testcase shows, we were generating invalid DWARF 3
for -gdwarf-3 for large DW_AT_data_member_location offsets.
Unlike DWARF 2, DWARF 3 allows DW_AT_data_member_location to be
either constant, block or loclistptr class, and for this combination
it has a note there that DW_FORM_data[48] (which are used for loclistptr)
aren't included then in constant class. We were generating a DW_FORM_data4
for the constant anyway, the following patch fixes it to generate
DW_FORM_udata in that case instead.
Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
Would this be appropriate for 4.6 too?
2011-07-27 Jakub Jelinek <ja...@redhat.com>
PR debug/49871
* dwarf2out.c (size_of_die, value_format, output_die): Use
DW_FORM_udata instead of DW_FORM_data[48] for
dw_val_class_unsigned_const DW_AT_data_member_location for DWARF 3.
* gcc.dg/debug/dwarf2/pr49871.c: New test.
--- gcc/dwarf2out.c.jj 2011-07-26 16:19:56.000000000 +0200
+++ gcc/dwarf2out.c 2011-07-27 18:55:11.000000000 +0200
@@ -7652,7 +7652,15 @@ size_of_die (dw_die_ref die)
size += size_of_sleb128 (AT_int (a));
break;
case dw_val_class_unsigned_const:
- size += constant_size (AT_unsigned (a));
+ {
+ int csize = constant_size (AT_unsigned (a));
+ if (dwarf_version == 3
+ && a->dw_attr == DW_AT_data_member_location
+ && csize >= 4)
+ size += size_of_uleb128 (AT_unsigned (a));
+ else
+ size += csize;
+ }
break;
case dw_val_class_const_double:
size += 2 * HOST_BITS_PER_WIDE_INT / HOST_BITS_PER_CHAR;
@@ -7953,8 +7961,16 @@ value_format (dw_attr_ref a)
case 2:
return DW_FORM_data2;
case 4:
+ /* In DWARF3 DW_AT_data_member_location with
+ DW_FORM_data4 or DW_FORM_data8 is a loclistptr, not
+ constant, so we need to use DW_FORM_udata if we need
+ a large constant. */
+ if (dwarf_version == 3 && a->dw_attr == DW_AT_data_member_location)
+ return DW_FORM_udata;
return DW_FORM_data4;
case 8:
+ if (dwarf_version == 3 && a->dw_attr == DW_AT_data_member_location)
+ return DW_FORM_udata;
return DW_FORM_data8;
default:
gcc_unreachable ();
@@ -8261,8 +8277,15 @@ output_die (dw_die_ref die)
break;
case dw_val_class_unsigned_const:
- dw2_asm_output_data (constant_size (AT_unsigned (a)),
- AT_unsigned (a), "%s", name);
+ {
+ int csize = constant_size (AT_unsigned (a));
+ if (dwarf_version == 3
+ && a->dw_attr == DW_AT_data_member_location
+ && csize >= 4)
+ dw2_asm_output_data_uleb128 (AT_unsigned (a), "%s", name);
+ else
+ dw2_asm_output_data (csize, AT_unsigned (a), "%s", name);
+ }
break;
case dw_val_class_const_double:
--- gcc/testsuite/gcc.dg/debug/dwarf2/pr49871.c.jj 2011-07-27
19:14:10.000000000 +0200
+++ gcc/testsuite/gcc.dg/debug/dwarf2/pr49871.c 2011-07-27 19:15:40.000000000
+0200
@@ -0,0 +1,12 @@
+/* PR debug/49871 */
+/* { dg-do compile } */
+/* { dg-options "-gdwarf-3 -dA -fno-merge-debug-strings" } */
+
+struct S
+{
+ char a[1 << 16];
+ int b;
+} s;
+
+/* { dg-final { scan-assembler
"\\(DW_AT_data_member_location\\)\[^\\r\\n\]*\[\\r\\n\]+\[^\\r\\n\]*\\(DW_FORM_udata\\)"
} } */
+/* { dg-final { scan-assembler-not
"\\(DW_AT_data_member_location\\)\[^\\r\\n\]*\[\\r\\n\]+\[^\\r\\n\]*\\(DW_FORM_data\[48\]\\)"
} } */
Jakub
