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. 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.
