on 2021/7/15 下午4:23, Uros Bizjak wrote: > On Thu, Jul 15, 2021 at 10:04 AM Kewen.Lin <li...@linux.ibm.com> wrote: >> >> Hi Uros, >> >> on 2021/7/15 下午3:17, Uros Bizjak wrote: >>> On Thu, Jul 15, 2021 at 9:07 AM Kewen.Lin <li...@linux.ibm.com> wrote: >>>> >>>> on 2021/7/14 下午3:45, Kewen.Lin via Gcc-patches wrote: >>>>> on 2021/7/14 下午2:38, Richard Biener wrote: >>>>>> On Tue, Jul 13, 2021 at 4:59 PM Kewen.Lin <li...@linux.ibm.com> wrote: >>>>>>> >>>>>>> on 2021/7/13 下午8:42, Richard Biener wrote: >>>>>>>> On Tue, Jul 13, 2021 at 12:25 PM Kewen.Lin <li...@linux.ibm.com> wrote: >>>>>> >>>>>>> I guess the proposed IFN would be directly mapped for [us]mul_highpart? >>>>>> >>>>>> Yes. >>>>>> >>>>> >>>>> Thanks for confirming! The related patch v2 is attached and the testing >>>>> is ongoing. >>>>> >>>> >>>> It's bootstrapped & regtested on powerpc64le-linux-gnu P9 and >>>> aarch64-linux-gnu. But on x86_64-redhat-linux there are XPASSes as below: >>>> >>>> XFAIL->XPASS: gcc.target/i386/pr100637-3w.c scan-assembler pmulhuw >>>> XFAIL->XPASS: gcc.target/i386/pr100637-3w.c scan-assembler pmulhuw >>>> XFAIL->XPASS: gcc.target/i386/pr100637-3w.c scan-assembler pmulhw >>>> XFAIL->XPASS: gcc.target/i386/pr100637-3w.c scan-assembler pmulhw >>> >>> These XFAILs should be removed after your patch. >>> >> I'm curious whether it's intentional not to specify -fno-vect-cost-model >> for this test case. As noted above, this case is sensitive on how we >> cost mult_highpart. Without cost modeling, the XFAILs can be removed >> only with this mul_highpart pattern support, no matter how we model it >> (x86 part of this patch exists or not). >> >>> This is PR100696 [1], we want PMULH.W here, so x86 part of the patch >>> is actually not needed. >>> >> >> Thanks for the information! The justification for the x86 part is that: >> the IFN_MULH essentially covers MULT_HIGHPART_EXPR with mul_highpart >> optab support, i386 port has already customized costing for >> MULT_HIGHPART_EXPR (should mean/involve the case with mul_highpart optab >> support), if we don't follow the same way for IFN_MULH, I'm worried that >> we may cost the IFN_MULH wrongly. If taking IFN_MULH as normal stmt is >> a right thing (we shouldn't cost it specially), it at least means we >> have to adjust ix86_multiplication_cost for MULT_HIGHPART_EXPR when it >> has direct mul_highpart optab support, I think they should be costed >> consistently. Does it sound reasonable? > > Ah, I was under impression that i386 part was introduced to avoid > generation of PMULHW instructions in the testcases above (to keep > XFAILs). Based on your explanation - yes, the costing function should > be the same. So, the x86 part is OK. >
Thanks! It does have the effect to keep XFAILs. ;) I guess the case doesn't care about the costing much just like most vectorization cases? If so, do you want me to remove the xfails with one extra option "-fno-vect-cost-model" along with this patch? BR, Kewen
