fix -fpic cse misses

[Richard Henderson <rth at redhat dot com>]

I noticed that no expressions involving the pic register
were being cse'd.  The problem is that the expression below
is ordered incorrectly -- %ebx fails because it is
CLASS_LIKELY_SPILLED_P.  Which we shouldn't be testing
because the register is fixed with -fpic.

An example of the improvement is

-       leal    cse_reg_info_free_list@GOTOFF(%ebx), %edx
-       movl    (%edx), %eax
+       movl    cse_reg_info_free_list@GOTOFF(%ebx), %eax
        testl   %eax, %eax
        je      .L239
-       movl    %eax, %ecx
+       movl    %eax, %edx
        movl    4(%eax), %eax
-       movl    %eax, (%edx)
+       movl    %eax, cse_reg_info_free_list@GOTOFF(%ebx)

where the invariant address is pulled into both the load
and store.  This is good for -216 instructions compiling
cse.c with -O2 -fpic.

Applied mainline and branch, since I'm certain that this
worked at some point in the past, and therefore must be
a regression.


r~


        * cse.c (canon_hash): Reorder do_not_record test.  Always
        allow pic_offset_table_rtx.

Index: cse.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/cse.c,v
retrieving revision 1.225
diff -c -p -d -r1.225 cse.c
*** cse.c	10 May 2002 18:58:00 -0000	1.225
--- cse.c	20 May 2002 09:56:58 -0000
*************** canon_hash (x, mode)
*** 2249,2258 ****
      case REG:
        {
  	unsigned int regno = REGNO (x);
  
  	/* On some machines, we can't record any non-fixed hard register,
  	   because extending its life will cause reload problems.  We
! 	   consider ap, fp, and sp to be fixed for this purpose.
  
  	   We also consider CCmode registers to be fixed for this purpose;
  	   failure to do so leads to failure to simplify 0<100 type of
--- 2249,2259 ----
      case REG:
        {
  	unsigned int regno = REGNO (x);
+ 	bool record;
  
  	/* On some machines, we can't record any non-fixed hard register,
  	   because extending its life will cause reload problems.  We
! 	   consider ap, fp, sp, gp to be fixed for this purpose.
  
  	   We also consider CCmode registers to be fixed for this purpose;
  	   failure to do so leads to failure to simplify 0<100 type of
*************** canon_hash (x, mode)
*** 2262,2277 ****
  	   Nor should we record any register that is in a small
  	   class, as defined by CLASS_LIKELY_SPILLED_P.  */
  
! 	if (regno < FIRST_PSEUDO_REGISTER
! 	    && (global_regs[regno]
! 		|| CLASS_LIKELY_SPILLED_P (REGNO_REG_CLASS (regno))
! 		|| (SMALL_REGISTER_CLASSES
! 		    && ! fixed_regs[regno]
! 		    && x != frame_pointer_rtx
! 		    && x != hard_frame_pointer_rtx
! 		    && x != arg_pointer_rtx
! 		    && x != stack_pointer_rtx
! 		    && GET_MODE_CLASS (GET_MODE (x)) != MODE_CC)))
  	  {
  	    do_not_record = 1;
  	    return 0;
--- 2263,2290 ----
  	   Nor should we record any register that is in a small
  	   class, as defined by CLASS_LIKELY_SPILLED_P.  */
  
! 	if (regno >= FIRST_PSEUDO_REGISTER)
! 	  record = true;
! 	else if (x == frame_pointer_rtx
! 		 || x == hard_frame_pointer_rtx
! 		 || x == arg_pointer_rtx
! 		 || x == stack_pointer_rtx
! 		 || x == pic_offset_table_rtx)
! 	  record = true;
! 	else if (global_regs[regno])
! 	  record = false;
! 	else if (fixed_regs[regno])
! 	  record = true;
! 	else if (GET_MODE_CLASS (GET_MODE (x)) == MODE_CC)
! 	  record = true;
! 	else if (SMALL_REGISTER_CLASSES)
! 	  record = false;
! 	else if (CLASS_LIKELY_SPILLED_P (REGNO_REG_CLASS (regno)))
! 	  record = false;
! 	else
! 	  record = true;
! 	    
! 	if (!record)
  	  {
  	    do_not_record = 1;
  	    return 0;