IA-64 patch for glibc 2.2 -O2 compile failure

[Jim Wilson]

The glibc 2.2 file iso646.c gets an ICE at -O2.  It hits the abort in
rws_access_reg because write_count is 4.  The problem is that the code
doesn't correctly handle overlapping predicate register pairs.  The
following patch fixes this.

2000-07-07  Jim Wilson  <wilson@cygnus.com>

	* config/ia64/ia64.c (rws_access_reg): New local write_count.  If
	is_predicate_reg, then take max write_count of register pair.

Index: ia64.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/config/ia64/ia64.c,v
retrieving revision 1.29
diff -p -r1.29 ia64.c
*** ia64.c	2000/07/01 21:20:32	1.29
--- ia64.c	2000/07/07 23:42:16
*************** rws_access_reg (regno, flags, pred)
*** 2313,2318 ****
--- 2313,2320 ----
  
    if (flags.is_write)
      {
+       int write_count;
+ 
        /* One insn writes same reg multiple times?  */
        if (rws_insn[regno].write_count > 0)
  	abort ();
*************** rws_access_reg (regno, flags, pred)
*** 2327,2334 ****
        is_predicate_reg = REGNO_REG_CLASS (regno) == PR_REGS;
        if (is_predicate_reg)
  	rws_update (rws_insn, regno + 1, flags, pred);
  
!       switch (rws_sum[regno].write_count)
  	{
  	case 0:
  	  /* The register has not been written yet.  */
--- 2329,2341 ----
        is_predicate_reg = REGNO_REG_CLASS (regno) == PR_REGS;
        if (is_predicate_reg)
  	rws_update (rws_insn, regno + 1, flags, pred);
+ 
+       /* ??? Likewise.  */
+       write_count = rws_sum[regno].write_count;
+       if (is_predicate_reg)
+ 	write_count = MAX (write_count, rws_sum[regno + 1].write_count);
  
!       switch (write_count)
  	{
  	case 0:
  	  /* The register has not been written yet.  */