From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by sourceware.org (Postfix) with ESMTP id 5B2B33858D20; Wed, 15 May 2024 10:56:28 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 5B2B33858D20 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=arm.com ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 5B2B33858D20 Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=217.140.110.172 ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1715770590; cv=none; b=GAcW8+moZjSj78z07PDqVDqCVsI87ODx8KdlTjjEqbeZMoJtMcxJWbh+eg2gj7TQPlzOgiSGlluK8enEzanGTAmQkrrhnJbSxLu9Dc2poILNJboAzCifN33bzUrhcCTKrVySyAMb6UaPiWs8L0G6ZBErCn9otz8q3y4VAyCUpiI= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1715770590; c=relaxed/simple; bh=ANQ7SfRU0lDVT3vBQBVF2j39/Y7qgeJR0KYX5OyzCtE=; h=From:To:Subject:Date:Message-ID:MIME-Version; b=JIIjfrmBRG+f9g1hwFJx7t+DrSDcWn/JrZoiUT18wr5NO/uDh57LHYpsqkND3t/svrbOa1zTb20bJUJOvsc8vBu18odALarAS1sRcYJUVsOBCaLcS8rmr1fulBLgNOuI7Uvf1nVaVeF9H0QIdAjgVK8uCjvxfASuyYHSopWyzyU= ARC-Authentication-Results: i=1; server2.sourceware.org Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B6FF01042; Wed, 15 May 2024 03:56:52 -0700 (PDT) Received: from localhost (e121540-lin.manchester.arm.com [10.32.110.72]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 318553F762; Wed, 15 May 2024 03:56:27 -0700 (PDT) From: Richard Sandiford To: Tamar Christina Mail-Followup-To: Tamar Christina ,gcc-patches@gcc.gnu.org, nd@arm.com, Richard.Earnshaw@arm.com, Marcus.Shawcroft@arm.com, ktkachov@gcc.gnu.org, richard.sandiford@arm.com Cc: gcc-patches@gcc.gnu.org, nd@arm.com, Richard.Earnshaw@arm.com, Marcus.Shawcroft@arm.com, ktkachov@gcc.gnu.org Subject: Re: [PATCH 2/4]AArch64: add new tuning param and attribute for enabling conditional early clobber References: Date: Wed, 15 May 2024 11:56:25 +0100 In-Reply-To: (Tamar Christina's message of "Wed, 15 May 2024 11:28:51 +0100") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-Spam-Status: No, score=-20.4 required=5.0 tests=BAYES_00,GIT_PATCH_0,KAM_DMARC_NONE,KAM_DMARC_STATUS,KAM_LAZY_DOMAIN_SECURITY,KAM_LOTSOFHASH,SPF_HELO_NONE,SPF_NONE,TXREP 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: Tamar Christina writes: > Hi All, > > This adds a new tuning parameter EARLY_CLOBBER_SVE_PRED_DEST for AArch64 to > allow us to conditionally enable the early clobber alternatives based on the > tuning models. > > Bootstrapped Regtested on aarch64-none-linux-gnu and no issues. > > Ok for master? > > Thanks, > Tamar > > gcc/ChangeLog: > > * config/aarch64/aarch64-tuning-flags.def > (EARLY_CLOBBER_SVE_PRED_DEST): New. > * config/aarch64/aarch64.h (TARGET_SVE_PRED_CLOBBER): New. > * config/aarch64/aarch64.md (pred_clobber): New. > (arch_enabled): Use it. > > --- > diff --git a/gcc/config/aarch64/aarch64-tuning-flags.def b/gcc/config/aarch64/aarch64-tuning-flags.def > index d5bcaebce770f0b217aac783063d39135f754c77..49fbad3ff28bc82b25c61ac501ccf533ec4b4c3f 100644 > --- a/gcc/config/aarch64/aarch64-tuning-flags.def > +++ b/gcc/config/aarch64/aarch64-tuning-flags.def > @@ -48,4 +48,8 @@ AARCH64_EXTRA_TUNING_OPTION ("avoid_cross_loop_fma", AVOID_CROSS_LOOP_FMA) > > AARCH64_EXTRA_TUNING_OPTION ("fully_pipelined_fma", FULLY_PIPELINED_FMA) > > +/* Enable is the target prefers to use a fresh register for predicate outputs > + rather than re-use an input predicate register. */ > +AARCH64_EXTRA_TUNING_OPTION ("early_clobber_sve_pred_dest", EARLY_CLOBBER_SVE_PRED_DEST) Sorry for the bike-shedding, but how about something like "avoid_pred_rmw"? (I'm open to other suggestions.) Just looking for something that describes either the architecture or the end result that we want to achieve. And preferable something fairly short :) avoid_* would be consistent with the existing "avoid_cross_loop_fma". > + > #undef AARCH64_EXTRA_TUNING_OPTION > diff --git a/gcc/config/aarch64/aarch64.h b/gcc/config/aarch64/aarch64.h > index bbf11faaf4b4340956094a983f8b0dc2649b2d27..76a18dd511f40ebb58ed12d56b46c74084ba7c3c 100644 > --- a/gcc/config/aarch64/aarch64.h > +++ b/gcc/config/aarch64/aarch64.h > @@ -495,6 +495,11 @@ constexpr auto AARCH64_FL_DEFAULT_ISA_MODE = AARCH64_FL_SM_OFF; > enabled through +gcs. */ > #define TARGET_GCS (AARCH64_ISA_GCS) > > +/* Prefer different predicate registers for the output of a predicated operation over > + re-using an existing input predicate. */ > +#define TARGET_SVE_PRED_CLOBBER (TARGET_SVE \ > + && (aarch64_tune_params.extra_tuning_flags \ > + & AARCH64_EXTRA_TUNE_EARLY_CLOBBER_SVE_PRED_DEST)) > > /* Standard register usage. */ > > diff --git a/gcc/config/aarch64/aarch64.md b/gcc/config/aarch64/aarch64.md > index dbde066f7478bec51a8703b017ea553aa98be309..1ecd1a2812969504bd5114a53473b478c5ddba82 100644 > --- a/gcc/config/aarch64/aarch64.md > +++ b/gcc/config/aarch64/aarch64.md > @@ -445,6 +445,10 @@ (define_enum_attr "arch" "arches" (const_string "any")) > ;; target-independent code. > (define_attr "is_call" "no,yes" (const_string "no")) > > +;; Indicates whether we want to enable the pattern with an optional early > +;; clobber for SVE predicates. > +(define_attr "pred_clobber" "no,yes" (const_string "no")) > + > ;; [For compatibility with Arm in pipeline models] > ;; Attribute that specifies whether or not the instruction touches fp > ;; registers. > @@ -461,7 +465,8 @@ (define_attr "fp" "no,yes" > (define_attr "arch_enabled" "no,yes" > (if_then_else > (ior > - (eq_attr "arch" "any") > + (and (eq_attr "arch" "any") > + (eq_attr "pred_clobber" "no")) > > (and (eq_attr "arch" "rcpc8_4") > (match_test "AARCH64_ISA_RCPC8_4")) > @@ -488,7 +493,10 @@ (define_attr "arch_enabled" "no,yes" > (match_test "TARGET_SVE")) > > (and (eq_attr "arch" "sme") > - (match_test "TARGET_SME"))) > + (match_test "TARGET_SME")) > + > + (and (eq_attr "pred_clobber" "yes") > + (match_test "TARGET_SVE_PRED_CLOBBER"))) IMO it'd be bettero handle pred_clobber separately from arch, as a new top-level AND: (and (ior (eq_attr "pred_clobber" "no") (match_test "!TARGET_...")) (ior ...existing arch tests...)) Thanks, Richard