Hi, Having stage1 close to end, may we make some decision regarding this patch? Having a couple of working variants, may we choose and use one of them?
Thanks, Ilya 2014-07-15 17:38 GMT+04:00 Uros Bizjak <ubiz...@gmail.com>: > On Tue, Jul 15, 2014 at 1:01 PM, Ilya Enkovich <enkovich....@gmail.com> wrote: >> On 15 Jul 10:42, Uros Bizjak wrote: >>> On Tue, Jul 15, 2014 at 10:25 AM, Ilya Enkovich <enkovich....@gmail.com> >>> wrote: >>> >>> >>>>> Also fully restrict xmm8-15 does not seem right. It is just costly >>> >>>>> but not fully disallowed. >>> >>>> >>> >>>> As said earlier, you can try "Ya*x" as a constraint. >>> >>> >>> >>> I tried it. It does not seem to affect allocation much. I do not see >>> >>> any gain on targeted tests. >>> >> >>> >> Strange, because the documentation claims: >>> >> >>> >> '*' >>> >> Says that the following character should be ignored when choosing >>> >> register preferences. '*' has no effect on the meaning of the >>> >> constraint as a constraint, and no effect on reloading. For LRA >>> >> '*' additionally disparages slightly the alternative if the >>> >> following character matches the operand. >>> >> >>> >> Let me rethink this a bit. Prehaps we could reconsider Jakub's >>> >> proposal with "Ya,!x" (with two alternatives). IIRC this approach was >>> >> needed for some MMX alternatives, where we didn't want RA to allocate >>> >> a MMX register when the value could be passed in integer regs, but the >>> >> value was still allowed in MMX register. >>> > >>> > That's is what my patch already does, but with '?' instead of '!'. >>> >>> Yes, I know. The problem is, that Ya*x type conditional allocation >>> worked OK in the past for "not preferred, but still alowed regclass" >>> registers, There are several patterns in i386.md that live by this >>> premise, including movsf_internal and movdf_internal. If this approach >>> doesn't work anymore, then we have to either figure out what is the >>> reason, or invent a new strategy that will be applicable to all cases. >>> >>> Can you please post a small test that illustrates the case where Ya,!x >>> works, but Ya*x doesn't? >> >> It's hard to compose a small testcase which will have SSE4 instructions >> generated with required register usage. I use tcpjumbo test from TCPmark >> for initial check of how my patch works. This test has a lot of pmovzxwd >> instructions generated and many of them use xmm8-15. I tried two versions >> of a simple patch which modifies only pmovzxwd instruction. >> >> Patch1: >> >> diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md >> index d907353..6b03b72 100644 >> --- a/gcc/config/i386/sse.md >> +++ b/gcc/config/i386/sse.md >> @@ -11852,10 +11852,10 @@ >> (set_attr "mode" "OI")]) >> >> (define_insn "sse4_1_<code>v4hiv4si2" >> - [(set (match_operand:V4SI 0 "register_operand" "=x") >> + [(set (match_operand:V4SI 0 "register_operand" "=Yr,!x") >> (any_extend:V4SI >> (vec_select:V4HI >> - (match_operand:V8HI 1 "nonimmediate_operand" "xm") >> + (match_operand:V8HI 1 "nonimmediate_operand" "Yr,!xm") >> (parallel [(const_int 0) (const_int 1) >> (const_int 2) (const_int 3)]))))] >> "TARGET_SSE4_1" >> >> Patch2: >> >> diff --git a/gcc/config/i386/sse.md b/gcc/config/i386/sse.md >> index d907353..b3721c4 100644 >> --- a/gcc/config/i386/sse.md >> +++ b/gcc/config/i386/sse.md >> @@ -11852,10 +11852,10 @@ >> (set_attr "mode" "OI")]) >> >> (define_insn "sse4_1_<code>v4hiv4si2" >> - [(set (match_operand:V4SI 0 "register_operand" "=x") >> + [(set (match_operand:V4SI 0 "register_operand" "=Yr*x") >> (any_extend:V4SI >> (vec_select:V4HI >> - (match_operand:V8HI 1 "nonimmediate_operand" "xm") >> + (match_operand:V8HI 1 "nonimmediate_operand" "Yr*xm") >> (parallel [(const_int 0) (const_int 1) >> (const_int 2) (const_int 3)]))))] >> "TARGET_SSE4_1" >> >> >> Here are results of looking for pmovzxwd in resulting binaries: >> #objdump -d tcpjumbo-orig | grep pmovzxwd | grep >> "xmm8\|xmm9\|xmm10\|xmm11\|xmm12\|xmm13\|xmm14\|xmm15" | wc -l >> 76 >> #objdump -d tcpjumbo-patch1 | grep pmovzxwd | grep >> "xmm8\|xmm9\|xmm10\|xmm11\|xmm12\|xmm13\|xmm14\|xmm15" | wc -l >> 0 >> #objdump -d tcpjumbo-patch2 | grep pmovzxwd | grep >> "xmm8\|xmm9\|xmm10\|xmm11\|xmm12\|xmm13\|xmm14\|xmm15" | wc -l >> 76 >> >> Therefore I make a conclusion that Yr*x does not really differ much from x. > > Just FTR: > > Using "Yr,*x" is also a viable option: > > #objdump -d tcpjumbo-patch3 | grep pmovzxwd | grep > "xmm8\|xmm9\|xmm10\|xmm11\|xmm12\|xmm13\|xmm14\|xmm15" | wc -l > 0 > > I believe that the above is the way to go with LRA. Vladimir, what do you > think? > > Uros.
