bug in new ia32 backend

[Mike Stump]

I have completed a full (gcc/g++/g77/objc/libio/libstdc++) testsuite
run (linux native), and only found one problem...

Merge droppage:

FAIL: gcc.dg/990424-1.c (test for excess errors)

caused by (i386.h):

!   { "preferred-stack-boundary=", &i386_preferred_stack_boundary_string, "Attem
pt to keep stack aligned to this power of 2" }, \
!   { "branch-cost=",   &i386_branch_cost_string, "Branches are this expensive (
1-5, arbitrary units)" },                       \

in pass0.  This wasn't in any of the raw patches, so this was a
clobber of new work, bad.  I'll see about auditing the raw files with
the pass0 file, and see what else I can come up with.  I was using the
first set of patches, and a very recent snapshot with fixes previously
described and an older loop.c with one seemingly related bug fix.

I see the branch is done, so I will switch over to it.

For completeness, below you will find what I tested with.

Doing diffs in .:
*** ./gcc/reg-stack.c.~1~	Fri Jun 18 15:03:49 1999
--- ./gcc/reg-stack.c	Fri Jun 18 16:38:40 1999
*************** stack_regs_mentioned (pat)
*** 374,379 ****
--- 374,382 ----
    register char *fmt;
    register int i;
  
+   if (pat == 0)
+     return 0;
+ 
    if (STACK_REG_P (pat))
      return 1;
  
*** ./gcc/unroll.c.~1~	Fri Jun 18 15:03:49 1999
--- ./gcc/unroll.c	Tue Jun 22 18:51:14 1999
*************** loop_iterations (loop_start, loop_end, l
*** 3669,3675 ****
  
    /* If there is a more than a single jump to the top of the loop
       we cannot (easily) determine the iteration count.  */
!   if (LABEL_NUSES (JUMP_LABEL (last_loop_insn)) > 1)
      {
        if (loop_dump_stream)
  	fprintf (loop_dump_stream,
--- 3669,3676 ----
  
    /* If there is a more than a single jump to the top of the loop
       we cannot (easily) determine the iteration count.  */
!   if (JUMP_LABEL (last_loop_insn) == 0
!       || LABEL_NUSES (JUMP_LABEL (last_loop_insn)) > 1)
      {
        if (loop_dump_stream)
  	fprintf (loop_dump_stream,
*** ./gcc/resource.c.~1~	Fri Jun 18 15:03:49 1999
--- ./gcc/resource.c	Tue Jun 22 14:28:14 1999
*************** find_free_register (current_insn, class_
*** 1263,1276 ****
  
    for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
      {
!       int success = 1;
  
!       if (! TEST_HARD_REG_BIT (reg_class_contents[class], i))
! 	continue;
!       for (j = HARD_REGNO_NREGS (i, mode) - 1; j >= 0; j--)
  	{
! 	  if (TEST_HARD_REG_BIT (*reg_set, i + j)
! 	      || TEST_HARD_REG_BIT (used.regs, i + j))
  	    {
  	      success = 0;
  	      break;
--- 1263,1295 ----
  
    for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
      {
!       int regno;
!       int success;
  
! #ifdef REG_ALLOC_ORDER
!       regno = reg_alloc_order [i];
! #else
!       regno = i;
! #endif
!  
!       /* Don't allocate fixed registers.  */
!       if (fixed_regs[regno])
!         continue;
!       /* Make sure the register is of the right class.  */
!       if (! TEST_HARD_REG_BIT (reg_class_contents[class], regno))
!         continue;
!       /* And can support the mode we need.  */
!       if (! HARD_REGNO_MODE_OK (regno, mode))
!         continue;
!       /* And that we don't create an extra save/restore.  */
!       if (! call_used_regs[regno] && ! regs_ever_live[regno])
!         continue;
!  
!       success = 1;
!       for (j = HARD_REGNO_NREGS (regno, mode) - 1; j >= 0; j--)
  	{
! 	  if (TEST_HARD_REG_BIT (*reg_set, regno + j)
! 	      || TEST_HARD_REG_BIT (used.regs, regno + j))
  	    {
  	      success = 0;
  	      break;
*************** find_free_register (current_insn, class_
*** 1278,1288 ****
  	}
        if (success)
  	{
! 	  for (j = HARD_REGNO_NREGS (i, mode) - 1; j >= 0; j--)
  	    {
! 	      SET_HARD_REG_BIT (*reg_set, i + j);
  	    }
! 	  return gen_rtx_REG (mode, i);
  	}
      }
    return NULL_RTX;
--- 1297,1307 ----
  	}
        if (success)
  	{
! 	  for (j = HARD_REGNO_NREGS (regno, mode) - 1; j >= 0; j--)
  	    {
! 	      SET_HARD_REG_BIT (*reg_set, regno + j);
  	    }
! 	  return gen_rtx_REG (mode, regno);
  	}
      }
    return NULL_RTX;
*** ./gcc/loop.c.~1~	Fri Jun 18 15:03:47 1999
--- ./gcc/loop.c	Wed Jun 23 18:49:35 1999
*************** combine_givs_p (g1, g2)
*** 6976,6982 ****
      return NULL_RTX;
  
    ret = comb = express_from (g1, g2);
!   if (g1->mode != g2->mode)
      ret = gen_lowpart (g2->mode, comb);
  
    /* If these givs are identical, they can be combined.  We use the results
--- 6976,6982 ----
      return NULL_RTX;
  
    ret = comb = express_from (g1, g2);
!   if (ret && g1->mode != g2->mode)
      ret = gen_lowpart (g2->mode, comb);
  
    /* If these givs are identical, they can be combined.  We use the results
--------------