From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-ej1-x633.google.com (mail-ej1-x633.google.com [IPv6:2a00:1450:4864:20::633]) by sourceware.org (Postfix) with ESMTPS id 203F13858D20; Wed, 31 May 2023 13:42:28 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 203F13858D20 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com Received: by mail-ej1-x633.google.com with SMTP id a640c23a62f3a-96f7bf3cf9eso1073314866b.0; Wed, 31 May 2023 06:42:28 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20221208; t=1685540547; x=1688132547; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:from:to:cc:subject:date:message-id:reply-to; bh=XFx2zUEEcOcbPboLQjnMQjSW+6b6Co64ChdLb+Ki/zU=; b=Q9rv0BifF9S+NFyPhNq8OBSUbuOaN/6R9T37XYmJlB6FpYh+wXYMo6LOjvKVV3nAOI qSaaBWgAw1kDk3JbCVzy9RrHozEtotrokMEPj2HqgdKk/5PAlcrGmj8hhq0HDQb2b4uU 3T37y8itZJSm2tQLyU8Ocx1xHgn6MFiY1hC9IAiLMCEbs+034/CAKGda06GMC4fA4tnO jnHBypdFhIYt91zit7bziAZYGhSdK4l80WNBpWhYfkQuCg6HVk7l/SliFm3DLJMcaQ/e KrlemOAQJSCU8757Lv/BTahTfMqTmXJShj/ZyeXuX6q9P67o85xqC0CdHLfo4bT0Fs/X SsLg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1685540547; x=1688132547; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=XFx2zUEEcOcbPboLQjnMQjSW+6b6Co64ChdLb+Ki/zU=; b=Jx3kovdRaY2lSAK10FLvP8JxBcIZhdkqe3MJqQJq8kH+4tGKcTAFR9Gunx9T71p43e iUBvWzy0wP+kEWIErDpTexs6geWiRVsgxY32QWrJ9eVuiEx8rKcU2R8AeRRvk7EXRXaO smYJQMSrn0gXKLoitEEOHONMb3ordBivezLUjLw9GW/FjrYg4y9aRQUlYlpTy5/T/Is/ HUN5E0PdmmVBZXy4nkX0US9GlH+KUVJbKVBq9bkEFOr2HyaCfIH0QhyhFz6fyPMqP11j BtqJeR68YIJkFCCFELk4mEySXjbmFOPvo78Wc/pk1kP1fv/4FAVjCOdguskzvea+lhVa 7+Pg== X-Gm-Message-State: AC+VfDyzzBtYsjmS2LFk7Upr4FqEcmDwA+Z7hNsEOrI5m/fZG3YkARGD SZGZWs9GmI/2/gHLf2EJlFXBE+6XhhfC9f2DtU7rBNzq X-Google-Smtp-Source: ACHHUZ7jx5KYqcmSb4ZAD70EZdD4k/V/Mp10Gltm3MBCharw/getKwuGBTXrN/Mk0/YfwAx6iPU+i0tUK+xnOXcLbvM= X-Received: by 2002:a17:907:2d0a:b0:974:1ef7:1e33 with SMTP id gs10-20020a1709072d0a00b009741ef71e33mr5901527ejc.8.1685540546506; Wed, 31 May 2023 06:42:26 -0700 (PDT) MIME-Version: 1.0 References: <20221014031748.55813-1-guojiufu@linux.ibm.com> <7npm7rkxrr.fsf@ltcden2-lp1.aus.stglabs.ibm.com> <7ncz2zpi81.fsf@ltcden2-lp1.aus.stglabs.ibm.com> <7npm6hxl1i.fsf_-_@ltcden2-lp1.aus.stglabs.ibm.com> In-Reply-To: <7npm6hxl1i.fsf_-_@ltcden2-lp1.aus.stglabs.ibm.com> From: David Edelsohn Date: Wed, 31 May 2023 09:40:34 -0400 Message-ID: Subject: Re: ping^^: [PATCH] rs6000: Enable const_anchor for 'addi' To: Jiufu Guo Cc: Jiufu Guo via Gcc-patches , segher@kernel.crashing.org, linkw@gcc.gnu.org Content-Type: multipart/alternative; boundary="0000000000008773d805fcfd7da1" X-Spam-Status: No, score=-7.3 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,GIT_PATCH_0,HTML_MESSAGE,KAM_SHORT,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP,T_SCC_BODY_TEXT_LINE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: --0000000000008773d805fcfd7da1 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, May 30, 2023 at 11:00=E2=80=AFPM Jiufu Guo = wrote: > > Gentle ping... > > Jiufu Guo via Gcc-patches writes: > > > Gentle ping... > > > > Jiufu Guo via Gcc-patches writes: > > > >> Hi, > >> > >> I'm thinking that we may enable this patch for stage1, so ping it. > >> https://gcc.gnu.org/pipermail/gcc-patches/2022-October/603530.html > >> > >> BR, > >> Jeff (Jiufu) > >> > >> Jiufu Guo writes: > >> > >>> Hi, > >>> > >>> There is a functionality as const_anchor in cse.cc. This const_anchor > >>> supports to generate new constants through adding small gap/offsets to > >>> existing constant. For example: > >>> > >>> void __attribute__ ((noinline)) foo (long long *a) > >>> { > >>> *a++ =3D 0x2351847027482577LL; > >>> *a++ =3D 0x2351847027482578LL; > >>> } > >>> The second constant (0x2351847027482578LL) can be compated by adding > '1' > >>> to the first constant (0x2351847027482577LL). > >>> This is profitable if more than one instructions are need to build the > >>> second constant. > >>> > >>> * For rs6000, we can enable this functionality, as the instruction > >>> 'addi' is just for this when gap is smaller than 0x8000. > >>> > >>> * Besides enabling TARGET_CONST_ANCHOR on rs6000, this patch also fix= ed > >>> one issue. The issue is: > >>> "gcc_assert (SCALAR_INT_MODE_P (mode))" is an requirement for function > >>> "try_const_anchors". > >>> > >>> * One potential side effect of this patch: > >>> Comparing with > >>> "r101=3D0x2351847027482577LL > >>> ... > >>> r201=3D0x2351847027482578LL" > >>> The new r201 will be "r201=3Dr101+1", and then r101 will live longer, > >>> and would increase pressure when allocating registers. > >>> But I feel, this would be acceptable for this const_anchor feature. > >>> > >>> * With this patch, I checked the performance change on SPEC2017, whil= e, > >>> and the performance is not aggressive, since this functionality is not > >>> hit on any hot path. There are runtime wavings/noise(e.g. on > >>> povray_r/xalancbmk_r/xz_r), that are not caused by the patch. > >>> > >>> With this patch, I also checked the changes in object files (from > >>> GCC bootstrap and SPEC), the significant changes are the improvement > >>> that: "addi" vs. "2 or more insns: lis+or.."; it also exposes some > >>> other optimizations opportunities: like combine/jump2. While the > >>> code to store/load one more register is also occurring in few cases, > >>> but it does not impact overall performance. > >>> > >>> * To refine this patch, some history discussions are referenced: > >>> https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D33699 > >>> https://gcc.gnu.org/pipermail/gcc-patches/2009-April/260421.html > >>> https://gcc.gnu.org/pipermail/gcc-patches/2021-March/566744.html > >>> > >>> > >>> Bootstrap and regtest pass on ppc64 and ppc64le for this patch. > >>> Is this ok for trunk? > Hi, Jiufu Thanks for developing this patch and your persistence. The rs6000.cc part of the patch (TARGET_CONST_ANCHOR) is okay for Stage 1. This is approved. I don't have the authority to approve the change to cse_insn. Is the cse_insn change a prerequisite? Will the rs6000 change break or produce wrong code without the cse change? The second part of the patch should be posted separately to the mailing list, with a cc for appropriate maintainers, because most maintainers will not be following this specific thread to approve the other part of the patch. Thanks, David > >>> > >>> > >>> BR, > >>> Jeff (Jiufu) > >>> > >>> gcc/ChangeLog: > >>> > >>> * config/rs6000/rs6000.cc (TARGET_CONST_ANCHOR): New define. > >>> * cse.cc (cse_insn): Add guard condition. > >>> > >>> gcc/testsuite/ChangeLog: > >>> > >>> * gcc.target/powerpc/const_anchors.c: New test. > >>> * gcc.target/powerpc/try_const_anchors_ice.c: New test. > >>> > >>> --- > >>> gcc/config/rs6000/rs6000.cc | 4 ++++ > >>> gcc/cse.cc | 3 ++- > >>> .../gcc.target/powerpc/const_anchors.c | 20 +++++++++++++++++= ++ > >>> .../powerpc/try_const_anchors_ice.c | 16 +++++++++++++++ > >>> 4 files changed, 42 insertions(+), 1 deletion(-) > >>> create mode 100644 gcc/testsuite/gcc.target/powerpc/const_anchors.c > >>> create mode 100644 > gcc/testsuite/gcc.target/powerpc/try_const_anchors_ice.c > >>> > >>> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc > >>> index d2743f7bce6..80cded6dec1 100644 > >>> --- a/gcc/config/rs6000/rs6000.cc > >>> +++ b/gcc/config/rs6000/rs6000.cc > >>> @@ -1760,6 +1760,10 @@ static const struct attribute_spec > rs6000_attribute_table[] =3D > >>> > >>> #undef TARGET_UPDATE_IPA_FN_TARGET_INFO > >>> #define TARGET_UPDATE_IPA_FN_TARGET_INFO > rs6000_update_ipa_fn_target_info > >>> + > >>> +#undef TARGET_CONST_ANCHOR > >>> +#define TARGET_CONST_ANCHOR 0x8000 > >>> + > >>> > >>> > >>> /* Processor table. */ > >>> diff --git a/gcc/cse.cc b/gcc/cse.cc > >>> index b13afd4ba72..56542b91c1e 100644 > >>> --- a/gcc/cse.cc > >>> +++ b/gcc/cse.cc > >>> @@ -5005,7 +5005,8 @@ cse_insn (rtx_insn *insn) > >>> if (targetm.const_anchor > >>> && !src_related > >>> && src_const > >>> - && GET_CODE (src_const) =3D=3D CONST_INT) > >>> + && GET_CODE (src_const) =3D=3D CONST_INT > >>> + && SCALAR_INT_MODE_P (mode)) > >>> { > >>> src_related =3D try_const_anchors (src_const, mode); > >>> src_related_is_const_anchor =3D src_related !=3D NULL_RTX; > >>> diff --git a/gcc/testsuite/gcc.target/powerpc/const_anchors.c > b/gcc/testsuite/gcc.target/powerpc/const_anchors.c > >>> new file mode 100644 > >>> index 00000000000..39958ff9765 > >>> --- /dev/null > >>> +++ b/gcc/testsuite/gcc.target/powerpc/const_anchors.c > >>> @@ -0,0 +1,20 @@ > >>> +/* { dg-do compile { target has_arch_ppc64 } } */ > >>> +/* { dg-options "-O2" } */ > >>> + > >>> +#define C1 0x2351847027482577ULL > >>> +#define C2 0x2351847027482578ULL > >>> + > >>> +void __attribute__ ((noinline)) foo (long long *a) > >>> +{ > >>> + *a++ =3D C1; > >>> + *a++ =3D C2; > >>> +} > >>> + > >>> +void __attribute__ ((noinline)) foo1 (long long *a, long long b) > >>> +{ > >>> + *a++ =3D C1; > >>> + if (b) > >>> + *a++ =3D C2; > >>> +} > >>> + > >>> +/* { dg-final { scan-assembler-times {\maddi\M} 2 } } */ > >>> diff --git a/gcc/testsuite/gcc.target/powerpc/try_const_anchors_ice.c > b/gcc/testsuite/gcc.target/powerpc/try_const_anchors_ice.c > >>> new file mode 100644 > >>> index 00000000000..4c8a892e803 > >>> --- /dev/null > >>> +++ b/gcc/testsuite/gcc.target/powerpc/try_const_anchors_ice.c > >>> @@ -0,0 +1,16 @@ > >>> +/* { dg-do compile } */ > >>> +/* { dg-options "-O2" } */ > >>> + > >>> +/* __builtin_stack_restore could generates {[%1:DI]=3D0;} in BLK mod= e, > >>> + it could case ICE in try_const_anchors which only supports > SCALAR_INT. */ > >>> + > >>> +long > >>> +foo (const int val) > >>> +{ > >>> + if (val =3D=3D (0)) > >>> + return 0; > >>> + void *p =3D __builtin_stack_save (); > >>> + char c =3D val; > >>> + __builtin_stack_restore (p); > >>> + return c; > >>> +} > --0000000000008773d805fcfd7da1--