[patch, mips] Follow up to pr54061 patch, fix another abort.

[Steve Ellcey]

While building libgcc in mips16 mode I found another instance of
dbx_reg_number aborting that the patch to pr54061 did not fix.
This code:

extern void __chk_fail (void) __attribute__ ((__noreturn__));
__strncpy_chk (s1, s2, n, s1len)
{
  char c;
  char *s = s1;
  if (__builtin_expect (s1len < n, 0))
    __chk_fail ();
  while (c != '\0');
  return s;
}

aborts when compiled with -O2 -g -fpic -mips16.  The following patch
fixes it.  OK to checkin?

Steve Ellcey
sell...@mips.com


2012-12-11  Steve Ellcey  <sell...@mips.com>

        * config/mips/mips.c (mips_option_override): Set
        mips_dbx_regno[CPRESTORE_SLOT_REGNUM] to IGNORED_DWARF_REGNUM.


diff --git a/gcc/config/mips/mips.c b/gcc/config/mips/mips.c
index 820b228..8113e5d 100644
--- a/gcc/config/mips/mips.c
+++ b/gcc/config/mips/mips.c
@@ -16760,6 +16760,8 @@ mips_option_override (void)
   for (i = ALL_COP_REG_FIRST; i <= ALL_COP_REG_LAST; i++)
     mips_dbx_regno[i] = IGNORED_DWARF_REGNUM;
 
+  mips_dbx_regno[CPRESTORE_SLOT_REGNUM] = IGNORED_DWARF_REGNUM;
+
   /* Accumulator debug registers use big-endian ordering.  */
   mips_dbx_regno[HI_REGNUM] = MD_DBX_FIRST + 0;
   mips_dbx_regno[LO_REGNUM] = MD_DBX_FIRST + 1;