On Fri, Jun 16, 2017 at 5:16 PM, Richard Biener <richard.guent...@gmail.com> wrote: > On June 16, 2017 3:31:32 PM GMT+02:00, "Bin.Cheng" <amker.ch...@gmail.com> > wrote: >>On Fri, Jun 16, 2017 at 2:10 PM, Richard Biener >><richard.guent...@gmail.com> wrote: >>> On Fri, Jun 16, 2017 at 3:06 PM, Bin.Cheng <amker.ch...@gmail.com> >>wrote: >>>> On Fri, Jun 16, 2017 at 11:49 AM, Richard Biener >>>> <richard.guent...@gmail.com> wrote: >>>>> On Wed, Jun 14, 2017 at 3:07 PM, Bin Cheng <bin.ch...@arm.com> >>wrote: >>>>>> Hi, >>>>>> Loop split forces intermediate computation to gimple operands all >>the time when >>>>>> computing bound information. This is not good since folding >>opportunities are >>>>>> missed. This patch fixes the issue by feeding all computation to >>folder and only >>>>>> forcing to gimple operand at last. >>>>>> >>>>>> Bootstrap and test on x86_64 and AArch64. Is it OK? >>>>> >>>>> Hm? It uses gimple_build () which should do the same as >>fold_buildN in terms >>>>> of simplification. >>>>> >>>>> So where does that not work? It is supposed to be the prefered way >>and no >>>>> new code should use force_gimple_operand (unless dealing with >>generic >>>>> coming from other middle-end infrastructure like SCEV or niter >>analysis) >>>> Hmm, current code calls force_gimpele operand several times which >>>> causes the inefficiency. The patch avoids that and does one call at >>>> the end. >>> >>> But it forces to the same sequence that is used for extending the >>expression >>> so folding should work. Where do you see that it does not? Note the >>> code uses gimple_build (), not gimple_build_assign (). >>In spec2k6/hmmer, when building fast_algorithms.c with below command >>line: >>./gcc -Ofast -S fast_algorithms.c -o fast_algorithms.S -fdump-tree-all >>-fdump-tree-lsplit >>The lsplit dump contains: >> <bb 11> [12.75%]: >> _124 = _197 + 1; >> _123 = _124 + -1; >> _115 = MIN_EXPR <_197, _124>; >>Which is generated here. > > That means we miss a pattern in match.PD to handle this case. I see. I will withdraw this patch and look in that direction.
Thanks, bin > > Richard. > >>Thanks, >>bin >>> >>> Richard. >>> >>>> Thanks, >>>> bin >>>>> >>>>> Richard. >>>>> >>>>>> >>>>>> Thanks, >>>>>> bin >>>>>> 2017-06-12 Bin Cheng <bin.ch...@arm.com> >>>>>> >>>>>> * tree-ssa-loop-split.c (compute_new_first_bound): Feed >>bound >>>>>> computation to folder, rather than force to gimple >>operands too >>>>>> early. >
