[commit, spu] Improve some comparison code sequences

[commit, spu] Improve some comparison code sequences

[Ulrich Weigand]

Hello,

this implements two minor enhancements to code generated by the
spu_emit_branch_or_set routine.

This reduces code size for the g++.dg/opt/longbranch1.C to the
extent that it once again fits into local store, and thus fixes
the failure.

Tested on spu-elf.
Committed to mainline.

Bye,
Ulrich


ChangeLog:

	* config/spu/spu.c (spu_emit_branch_or_set): Avoid reverse tests
	when generating an integer result where possible.  Short-cut
	comparison against 0 also for QImode.

Index: gcc/config/spu/spu.c
===================================================================
*** gcc/config/spu/spu.c	(revision 177794)
--- gcc/config/spu/spu.c	(working copy)
*************** spu_emit_branch_or_set (int is_set, rtx 
*** 982,987 ****
--- 982,1008 ----
  	  }
      }
  
+   /* However, if we generate an integer result, performing a reverse test
+      would require an extra negation, so avoid that where possible.  */
+   if (GET_CODE (op1) == CONST_INT && is_set == 1)
+     {
+       HOST_WIDE_INT val = INTVAL (op1) + 1;
+       if (trunc_int_for_mode (val, GET_MODE (op0)) == val)
+ 	switch (code)
+ 	  {
+ 	  case LE:
+ 	    op1 = GEN_INT (val);
+ 	    code = LT;
+ 	    break;
+ 	  case LEU:
+ 	    op1 = GEN_INT (val);
+ 	    code = LTU;
+ 	    break;
+ 	  default:
+ 	    break;
+ 	  }
+     }
+ 
    comp_mode = SImode;
    op_mode = GET_MODE (op0);
  
*************** spu_emit_branch_or_set (int is_set, rtx 
*** 1113,1119 ****
  
    if (is_set == 0 && op1 == const0_rtx
        && (GET_MODE (op0) == SImode
! 	  || GET_MODE (op0) == HImode) && scode == SPU_EQ)
      {
        /* Don't need to set a register with the result when we are 
           comparing against zero and branching. */
--- 1134,1141 ----
  
    if (is_set == 0 && op1 == const0_rtx
        && (GET_MODE (op0) == SImode
! 	  || GET_MODE (op0) == HImode
! 	  || GET_MODE (op0) == QImode) && scode == SPU_EQ)
      {
        /* Don't need to set a register with the result when we are 
           comparing against zero and branching. */
-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com