[patch, mips, debug] Fix PR 54061, mips compiler aborts in testsuite

[Steve Ellcey]

This is my attempt to fix PR 54061, a bug where GCC aborts while trying to
put out debug information for a co-processor register.  My understanding is
that gdb cannot access the coprocessor registers and so there is no valid
debug information that can be put out for this case.  So my fix is to remove
the assert from dbx_reg_number and change the callers to check for a
INVALID_REGNUM value coming from dbx_reg_number.  If they get this value
then they do not put out any debug information for the register.  I have
tested this on gcc.c-torture/compile/mipscop-[1234].c and it fixes the abort.

I haven't done a full regression test but will do that shortly, in the mean
time I wanted to see if this approach was considered acceptable and if not,
how I should fix it?

Steve Ellcey
sell...@mips.com


2012-12-07  Steve Ellcey  <sell...@mips.com>

        PR target/54061
        * dwarfwout.c (dbx_reg_number): Remove assert.
        (reg_loc_descriptor): Check for INVALID_REGNUM.
        (mem_loc_descriptor): Ditto.

diff --git a/gcc/dwarf2out.c b/gcc/dwarf2out.c
index f0256ae..7d26e7e 100644
--- a/gcc/dwarf2out.c
+++ b/gcc/dwarf2out.c
@@ -10438,7 +10438,6 @@ dbx_reg_number (const_rtx rtl)
 #endif
 
   regno = DBX_REGISTER_NUMBER (regno);
-  gcc_assert (regno != INVALID_REGNUM);
   return regno;
 }
 
@@ -10473,6 +10472,9 @@ reg_loc_descriptor (rtx rtl, enum var_init_status 
initialized)
   if (REGNO (rtl) >= FIRST_PSEUDO_REGISTER)
     return 0;
 
+  if (dbx_reg_number(rtl) == INVALID_REGNUM)
+    return 0;
+
   /* We only use "frame base" when we're sure we're talking about the
      post-prologue local stack frame.  We do this by *not* running
      register elimination until this point, and recognizing the special
@@ -11931,6 +11933,8 @@ mem_loc_descriptor (rtx rtl, enum machine_mode mode,
            break;
          if (REGNO (rtl) > FIRST_PSEUDO_REGISTER)
            break;
+         if (dbx_reg_number (rtl) == INVALID_REGNUM)
+           break;
          type_die = base_type_for_mode (mode,
                                         GET_MODE_CLASS (mode) == MODE_INT);
          if (type_die == NULL)
@@ -12133,6 +12137,9 @@ mem_loc_descriptor (rtx rtl, enum machine_mode mode,
        return NULL;
       if (REG_P (ENTRY_VALUE_EXP (rtl)))
        {
+         if (dbx_reg_number (ENTRY_VALUE_EXP (rtl)) == INVALID_REGNUM)
+           return NULL;
+
          if (GET_MODE_CLASS (mode) != MODE_INT
              || GET_MODE_SIZE (mode) > DWARF2_ADDR_SIZE)
            op0 = mem_loc_descriptor (ENTRY_VALUE_EXP (rtl), mode,