[PATCH 4/5] Altera Nios II: dwarf generation fix

[Cary Coutant]

On Thu, Apr 18, 2013 at 6:49 AM, Chung-Lin Tang <cltang@codesourcery.com> wrote:
> This patch was a fix by Julian which corrected a HOST_BITS_PER_WIDE_INT
> host dependency in dwarf generation. Nios II does not have
> need_64bit_hwint switched on during configuring, and ran into GDB test
> FAILs originating from this problem.
>
> 2013-04-18  Julian Brown  <julian@codesourcery.com>
>
>         * dwarf2out.c (gen_enumeration_type_die): Fix
>         HOST_BITS_PER_WIDE_INT dependency behavior in enumeration type
>         DIE generation.

+  if (host_integerp (value, TYPE_UNSIGNED (TREE_TYPE (value)))
+      && (simple_type_size_in_bits (TREE_TYPE (value))
+  <= HOST_BITS_PER_WIDE_INT || host_integerp (value, 0)))
     /* 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.  */
+    add_AT_int (enum_die, DW_AT_const_value, TREE_INT_CST_LOW (value));
+  else
+    /* Enumeration constants may be wider than HOST_WIDE_INT.  Handle
+       that here.  */
+    add_AT_double (enum_die, DW_AT_const_value,
+                   TREE_INT_CST_HIGH (value), TREE_INT_CST_LOW (value));

I'm not sure I understand the logic here. I'd think either the value
fits in a signed HOST_WIDE_INT, and we use add_AT_int, or it doesn't,
and we use add_AT_double:

  if (host_integerp (value, 0))
    add_AT_int (enum_die, DW_AT_const_value, TREE_INT_CST_LOW (value));
  else
    add_AT_double (enum_die, DW_AT_const_value,
                   TREE_INT_CST_HIGH (value), TREE_INT_CST_LOW (value));

Why wouldn't that work? I'd think this would even eliminate the need
for the comment about signed vs. unsigned.

-cary