From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-lf1-x12a.google.com (mail-lf1-x12a.google.com [IPv6:2a00:1450:4864:20::12a]) by sourceware.org (Postfix) with ESMTPS id 60F543858415 for ; Fri, 5 Apr 2024 12:43:36 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org 60F543858415 Authentication-Results: sourceware.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: sourceware.org; spf=pass smtp.mailfrom=gmail.com ARC-Filter: OpenARC Filter v1.0.0 sourceware.org 60F543858415 Authentication-Results: server2.sourceware.org; arc=none smtp.remote-ip=2a00:1450:4864:20::12a ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1712321021; cv=none; b=HZrv2gWVL/cQoR7OJOKhtZoSvjMPiaqZQenlNCeNPjbH/1hPWTiNf98u4EiE5wsFhc/hDV4RVBQ62FWTJ6MWgXiASOMiUMdDAatBi6LwPOKsjYW1ZgTCjvwmqwK+5Ekn2ZT9O8tu9bMQ74af8heiKRnI7eGCKMP0KIlR1/Fwabg= ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1712321021; c=relaxed/simple; bh=y6jaaMzhWECof2Iv0uIiMXhkqDYQwlNEh3maG3Ubz1A=; h=DKIM-Signature:MIME-Version:From:Date:Message-ID:Subject:To; b=bRun81xhk9lO7TQZ9RzapJKy354I/TKbTVhrj31bALwQZQx03NZ8I8oCI3n7NyiTFSwTztyTtv2FyCi/f6Ev4CikjwZ2wVeaBvIVGBhmVOjev3u0SfW8+8yqkfqduifQoFb1oqNURyPjEAYziBu8qjTvZdQwMkgzVwt8SyfOQf0= ARC-Authentication-Results: i=1; server2.sourceware.org Received: by mail-lf1-x12a.google.com with SMTP id 2adb3069b0e04-516d727074eso221564e87.0 for ; Fri, 05 Apr 2024 05:43:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1712321015; x=1712925815; darn=gcc.gnu.org; h=content-transfer-encoding:cc:to:subject:message-id:date:from :in-reply-to:references:mime-version:from:to:cc:subject:date :message-id:reply-to; bh=JAzL8anaRkgFLDG+3AK20PI6djajSUZY2oYdIzTaWA0=; b=jAWcam2g5a8GhAOaDLmyWjPYfO9QMs7MvXu2xM183WJgWpa0/6yu7rTMvWAeq3lfNT Rny+KGT0klIZqsEivO7DFFsguk1qPm44kBioe7ZQMxB0z4LwmYggNgu2KL9PIhrioAX6 6duLTi3oF/ZIk4XzW6jOz5XEIy0ESVNLndfKMyO7NlFSbDWyuW888DRfDPfB/wg0XttM yguhVUTbyw/4pXw8aoQFEMFA5gJ4G/mZW+fbeBvr6CT7PfMrVrRgN3rnwb564dAWIjME ifEzym/rxlF6PhriIXcL1gWqFExqz3vlMIqx5DmGF2l3+8ou4mEsvt4jim5zX+etYfqm d1Kg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1712321015; x=1712925815; h=content-transfer-encoding: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=JAzL8anaRkgFLDG+3AK20PI6djajSUZY2oYdIzTaWA0=; b=A9LOD/p7EC8FmZgNvOdUgBxFYLq4+arpho/XnlvyWQdxYH1bjavH0lIaNIl+FYVzLr Aa2KEc5Ab6E8ANTEtRcquxuqmxYrgRD9r5Yu34uiHFfUiwI7ygS5S7D7vb1a2Ll4tyou Mbq7LRe5iLPViipUzj0QXEycjKGTUBlgrp2vN0DZyB/eMu2LgjCsH2bhZ4UrWuU1HsL/ sdgzlpGYLETKky0gjrKZ87mMSWyFiw2ONDctaD0IhdGxvbvBYdWjm6ilUMzIFLXKgI1p hExvWBjbMrTWemDFfPHXdFQVy7vnROTVs8C5vxijJuA7AMeGg7hMZOSeXQZbDpn4jOsP CSBA== X-Gm-Message-State: AOJu0Yyx0PNaNzKaHoPojII3PYo19HTJnVNoccAotSayxlTy4wdoMCGR qY3z4vuTG53X70Yi9tdgcDRFgpLZaSHxBkfWA6DlJiiiNrJ24p5dU4L2N46Jm6B3ck83ZoVqi5C MKEjV8Q8HZyZ2jCPXQ8HneaRq1XU= X-Google-Smtp-Source: AGHT+IHrS1J4K9uxktewYkpuXJ3dNi1/NdU1vDC3ifSaFxxe81krYZi31389bkGKRm0LZFsRlvlHDAykEAoBuG2MbyU= X-Received: by 2002:a19:e04a:0:b0:516:d1af:e4e9 with SMTP id g10-20020a19e04a000000b00516d1afe4e9mr969269lfj.25.1712321014443; Fri, 05 Apr 2024 05:43:34 -0700 (PDT) MIME-Version: 1.0 References: <20240405122625.847311-1-manolis.tsamis@vrull.eu> In-Reply-To: <20240405122625.847311-1-manolis.tsamis@vrull.eu> From: Richard Biener Date: Fri, 5 Apr 2024 14:43:23 +0200 Message-ID: Subject: Re: [PATCH] Add extra copy of the ifcombine pass after pre [PR102793] To: Manolis Tsamis Cc: gcc-patches@gcc.gnu.org, Andrew Pinski , Philipp Tomsich , Tamar Christina , Jiangning Liu Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Spam-Status: No, score=-7.5 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,GIT_PATCH_0,KAM_SHORT,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,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: On Fri, Apr 5, 2024 at 2:28=E2=80=AFPM Manolis Tsamis wrote: > > If we consider code like: > > if (bar1 =3D=3D x) > return foo(); > if (bar2 !=3D y) > return foo(); > return 0; > > We would like the ifcombine pass to convert this to: > > if (bar1 =3D=3D x || bar2 !=3D y) > return foo(); > return 0; > > The ifcombine pass can handle this transformation but it is ran very earl= y and > it misses the opportunity because there are two seperate blocks for foo()= . > The pre pass is good at removing duplicate code and blocks and due to tha= t > running ifcombine again after it can increase the number of successful > conversions. > > PR 102793 > > gcc/ChangeLog: > > * common.opt: -ftree-ifcombine option, enabled by default. > * doc/invoke.texi: Document. > * passes.def: Re-run ssa-ifcombine after pre. > * tree-ssa-ifcombine.cc: Make ifcombine cloneable. Add gate funct= ion. > > gcc/testsuite/ChangeLog: > > * gcc.dg/tree-ssa/20030922-2.c: Change flag to -fno-tree-ifcombin= e. > * gcc.dg/uninit-pred-6_c.c: Remove inconsistent check. > * gcc.target/aarch64/pr102793.c: New test. > > Signed-off-by: Manolis Tsamis > --- > > gcc/common.opt | 4 +++ > gcc/doc/invoke.texi | 5 ++++ > gcc/passes.def | 1 + > gcc/testsuite/gcc.dg/tree-ssa/20030922-2.c | 2 +- > gcc/testsuite/gcc.dg/uninit-pred-6_c.c | 4 --- > gcc/testsuite/gcc.target/aarch64/pr102793.c | 30 +++++++++++++++++++++ > gcc/tree-ssa-ifcombine.cc | 5 ++++ > 7 files changed, 46 insertions(+), 5 deletions(-) > create mode 100644 gcc/testsuite/gcc.target/aarch64/pr102793.c > > diff --git a/gcc/common.opt b/gcc/common.opt > index ad348844775..e943202bcf1 100644 > --- a/gcc/common.opt > +++ b/gcc/common.opt > @@ -3163,6 +3163,10 @@ ftree-phiprop > Common Var(flag_tree_phiprop) Init(1) Optimization > Enable hoisting loads from conditional pointers. > > +ftree-ifcombine Please don't add further -ftree-X flags, 'tree' means nothing to users. -fif-combine would be better. > +Common Var(flag_tree_ifcombine) Init(1) Optimization > +Merge some conditional branches to simplify control flow. > + > ftree-pre > Common Var(flag_tree_pre) Optimization > Enable SSA-PRE optimization on trees. > diff --git a/gcc/doc/invoke.texi b/gcc/doc/invoke.texi > index e2edf7a6c13..8d2ff6b4512 100644 > --- a/gcc/doc/invoke.texi > +++ b/gcc/doc/invoke.texi > @@ -13454,6 +13454,11 @@ This flag is enabled by default at @option{-O1} = and higher. > Perform hoisting of loads from conditional pointers on trees. This > pass is enabled by default at @option{-O1} and higher. > > +@opindex ftree-ifcombine > +@item -ftree-ifcombine > +Merge some conditional branches to simplify control flow. This pass > +is enabled by default at @option{-O1} and higher. > + > @opindex fhoist-adjacent-loads > @item -fhoist-adjacent-loads > Speculatively hoist loads from both branches of an if-then-else if the > diff --git a/gcc/passes.def b/gcc/passes.def > index 1cbbd413097..1765b476131 100644 > --- a/gcc/passes.def > +++ b/gcc/passes.def > @@ -270,6 +270,7 @@ along with GCC; see the file COPYING3. If not see > NEXT_PASS (pass_lim); > NEXT_PASS (pass_walloca, false); > NEXT_PASS (pass_pre); > + NEXT_PASS (pass_tree_ifcombine); > NEXT_PASS (pass_sink_code, false /* unsplit edges */); Please move it here, after sinking. > NEXT_PASS (pass_sancov); > NEXT_PASS (pass_asan); > diff --git a/gcc/testsuite/gcc.dg/tree-ssa/20030922-2.c b/gcc/testsuite/g= cc.dg/tree-ssa/20030922-2.c > index 16c79da9521..66c9f481a2f 100644 > --- a/gcc/testsuite/gcc.dg/tree-ssa/20030922-2.c > +++ b/gcc/testsuite/gcc.dg/tree-ssa/20030922-2.c > @@ -1,5 +1,5 @@ > /* { dg-do compile } */ > -/* { dg-options "-O1 -fdump-tree-dom2 -fdisable-tree-ifcombine" } */ > +/* { dg-options "-O1 -fdump-tree-dom2 -fno-tree-ifcombine" } */ > > struct rtx_def; > typedef struct rtx_def *rtx; > diff --git a/gcc/testsuite/gcc.dg/uninit-pred-6_c.c b/gcc/testsuite/gcc.d= g/uninit-pred-6_c.c > index f60868dad23..2d8e6501a45 100644 > --- a/gcc/testsuite/gcc.dg/uninit-pred-6_c.c > +++ b/gcc/testsuite/gcc.dg/uninit-pred-6_c.c > @@ -20,10 +20,6 @@ int foo (int n, int l, int m, int r) > if ( (n > 10) && l) > blah(v); /* { dg-bogus "uninitialized" "bogus warning" } */ > > - if (l) > - if (n > 12) > - blah(v); /* { dg-bogus "uninitialized" "bogus warning" } */ > - What's "inconsistent" about this check? I suppose we now diagnose this? The appropriate way would be to XFAIL this but I'd like you to explain why we now diagnose this (I don't see obvious if-combining opportunities). On a general note you rely on the tail-merging pass which is part of PRE and which hasn't seen any love and which isn't very powerful either. I'm n= ot sure it's worth doing if-combining on the whole IL again because of it. It might be possible to locally try if-combining from the immediate dominat= or of a merged tail from inside tail-merging itself? Richard. > return 0; > } > > diff --git a/gcc/testsuite/gcc.target/aarch64/pr102793.c b/gcc/testsuite/= gcc.target/aarch64/pr102793.c > new file mode 100644 > index 00000000000..78d48e01637 > --- /dev/null > +++ b/gcc/testsuite/gcc.target/aarch64/pr102793.c > @@ -0,0 +1,30 @@ > +/* { dg-do compile } */ > +/* { dg-options "-O2" } */ > + > +typedef unsigned long uint64_t; > + > +int ccmp1(uint64_t* s1, uint64_t* s2, int(*foo)(void)) > +{ > + uint64_t d1, d2, bar; > + d1 =3D *s1++; > + d2 =3D *s2++; > + bar =3D (d1 + d2) & 0xabcd; > + if (bar =3D=3D 0 || d1 !=3D d2) > + return foo(); > + return 0; > +} > + > +int ccmp2(uint64_t* s1, uint64_t* s2, int(*foo)(void)) > +{ > + uint64_t d1, d2, bar; > + d1 =3D *s1++; > + d2 =3D *s2++; > + bar =3D (d1 + d2) & 0xabcd; > + if (bar =3D=3D 0) > + return foo(); > + if (d1 !=3D d2) > + return foo(); > + return 0; > +} > + > +/* { dg-final { scan-assembler-times "ccmp\t" 2 } } */ > \ No newline at end of file > diff --git a/gcc/tree-ssa-ifcombine.cc b/gcc/tree-ssa-ifcombine.cc > index 6a3bc99190d..0bf9fe8b692 100644 > --- a/gcc/tree-ssa-ifcombine.cc > +++ b/gcc/tree-ssa-ifcombine.cc > @@ -838,6 +838,11 @@ public: > {} > > /* opt_pass methods: */ > + opt_pass * clone () final override > + { > + return new pass_tree_ifcombine (m_ctxt); > + } > + bool gate (function *) final override { return flag_tree_ifcombine; } > unsigned int execute (function *) final override; > > }; // class pass_tree_ifcombine > -- > 2.44.0 >