Re: Optimizations on long long multiply/divide on PowerPC32 don't work

[Richard Henderson <rth@redhat.com>]

On Mon, Dec 10, 2001 at 12:54:44AM -0800, Richard Henderson wrote:
> GCC knows how to do this.  It will do this if the target supports
> all of these operations on 64 bit data types and it considers them
> to be cheap enough.

How irritating.  I do not like the taste of crow.

While the above is true, powerpc apparently has a rather cheap 32-bit
divide instruction which throws off the heuristics in this case.


r~



Index: expmed.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/expmed.c,v
retrieving revision 1.97
diff -c -p -d -r1.97 expmed.c
*** expmed.c	2001/11/20 04:12:11	1.97
--- expmed.c	2001/12/10 09:07:20
*************** expand_divmod (rem_flag, code, mode, op0
*** 3271,3277 ****
  		      goto fail1;
  		  }
  		else if (EXACT_POWER_OF_2_OR_ZERO_P (d)
! 			 && (rem_flag ? smod_pow2_cheap : sdiv_pow2_cheap))
  		  ;
  		else if (EXACT_POWER_OF_2_OR_ZERO_P (abs_d))
  		  {
--- 3271,3286 ----
  		      goto fail1;
  		  }
  		else if (EXACT_POWER_OF_2_OR_ZERO_P (d)
! 			 && (rem_flag ? smod_pow2_cheap : sdiv_pow2_cheap)
! 			 /* ??? The cheap metric is computed only for
! 			    word_mode.  If this operation is wider, this may
! 			    not be so.  Assume true if the optab has an
! 			    expander for this mode.  */
! 			 && (((rem_flag ? smod_optab : sdiv_optab)
! 			      ->handlers[(int) compute_mode].insn_code
! 			      != CODE_FOR_nothing)
! 			     || (sdivmod_optab->handlers[(int) compute_mode]
! 				 .insn_code != CODE_FOR_nothing)))
  		  ;
  		else if (EXACT_POWER_OF_2_OR_ZERO_P (abs_d))
  		  {