[PATCH] Add DW_AT_const_value as unsigned or int depending on type and value used.

[Mark Wielaard]

As the comment in the code already indicated DWARF2 does provide
DW_FORM_sdata/DW_FORM_udata to represent signed/unsigned data.
Enumeration constants wider than HOST_WIDE_INT are already handled
separately. Those constant values that do fit a HOST_WIDE_INT can
be encoded as signed or unsigned depending on type and value for
more efficient encoding.

        * dwarf2out.c (gen_enumeration_type_die): Add DW_AT_const_value
        as unsigned or int depending on type and value used.
---
 gcc/ChangeLog   |    5 +++++
 gcc/dwarf2out.c |   21 ++++++++-------------
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8a31187..f3b4f2d 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,8 @@
+2014-03-21  Mark Wielaard  <m...@redhat.com>
+
+       * dwarf2out.c (gen_enumeration_type_die): Add DW_AT_const_value
+       as unsigned or int depending on type and value used.
+
 2014-03-20  Mark Wielaard  <m...@redhat.com>
 
        * dwarf2out.c (add_bound_info): If HOST_WIDE_INT is big enough,
diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index 9f8b3b0..af97408 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -17364,19 +17364,14 @@ gen_enumeration_type_die (tree type, dw_die_ref 
context_die)
 
          if (simple_type_size_in_bits (TREE_TYPE (value))
              <= HOST_BITS_PER_WIDE_INT || tree_fits_shwi_p (value))
-           /* DWARF2 does not provide a way of indicating whether or
-              not enumeration constants are signed or unsigned.  GDB
-              always assumes the values are signed, so we output all
-              values as if they were signed.  That means that
-              enumeration constants with very large unsigned values
-              will appear to have negative values in the debugger.
-
-              TODO: the above comment is wrong, DWARF2 does provide
-              DW_FORM_sdata/DW_FORM_udata to represent signed/unsigned data.
-              This should be re-worked to use correct signed/unsigned
-              int/double tags for all cases, instead of always treating as
-              signed.  */
-           add_AT_int (enum_die, DW_AT_const_value, TREE_INT_CST_LOW (value));
+           {
+             HOST_WIDE_INT val = TREE_INT_CST_LOW (value);
+             if (TYPE_UNSIGNED (TREE_TYPE (value)) || val >= 0)
+               add_AT_unsigned (enum_die, DW_AT_const_value,
+                                (unsigned HOST_WIDE_INT) val);
+             else
+               add_AT_int (enum_die, DW_AT_const_value, val);
+           }
          else
            /* Enumeration constants may be wider than HOST_WIDE_INT.  Handle
               that here.  */
-- 
1.7.1