From patchwork Mon Dec 22 09:44:50 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Bin.Cheng" X-Patchwork-Id: 423330 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from sourceware.org (server1.sourceware.org [209.132.180.131]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 7C37C14007D for ; Mon, 22 Dec 2014 20:45:03 +1100 (AEDT) DomainKey-Signature: a=rsa-sha1; c=nofws; d=gcc.gnu.org; h=list-id :list-unsubscribe:list-archive:list-post:list-help:sender :mime-version:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; q=dns; s=default; b=jcsvPb197t/ZmkYR/t +PYdLQ9xfG/F+VERc70ZEQ67DLxiCflNG4jcQOjnT79lgb/RfKx821RLJLAJYsv1 +DGRfdlCk3FlxWvFmSs9u9JG46R0hsVozCJNE8n76JzbiZR4P94338aeAvogzj/4 dDQU/5TA+niCeiQ1J/o0c1h3Y= DKIM-Signature: v=1; a=rsa-sha1; c=relaxed; d=gcc.gnu.org; h=list-id :list-unsubscribe:list-archive:list-post:list-help:sender :mime-version:in-reply-to:references:date:message-id:subject :from:to:cc:content-type; s=default; bh=7zGkC+c9pX1c6zfY16Keg/QE Vtg=; b=jv9WwlwqEX7gmQEvelR6yod7Y3xalykEs5Q1Y6R0Bq9mphm+oflu5e0E b+DDt0re6vJZYlOhkl6HkcRIYZS6qOgBIFsu0nnIX3T3fHbvoaGy5PwIRCfTEXX0 EUsAURlvOty3tPK2qeCDzHenW1J2cWONHNN5Y1aGZFItnJ/HQpY= Received: (qmail 13490 invoked by alias); 22 Dec 2014 09:44:55 -0000 Mailing-List: contact gcc-patches-help@gcc.gnu.org; run by ezmlm Precedence: bulk List-Id: List-Unsubscribe: List-Archive: List-Post: List-Help: Sender: gcc-patches-owner@gcc.gnu.org Delivered-To: mailing list gcc-patches@gcc.gnu.org Received: (qmail 13475 invoked by uid 89); 22 Dec 2014 09:44:54 -0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.2 required=5.0 tests=AWL, BAYES_00, FREEMAIL_FROM, RCVD_IN_DNSWL_LOW, SPF_PASS autolearn=ham version=3.3.2 X-HELO: mail-ob0-f170.google.com Received: from mail-ob0-f170.google.com (HELO mail-ob0-f170.google.com) (209.85.214.170) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-SHA encrypted) ESMTPS; Mon, 22 Dec 2014 09:44:52 +0000 Received: by mail-ob0-f170.google.com with SMTP id wp18so20417749obc.1 for ; Mon, 22 Dec 2014 01:44:50 -0800 (PST) MIME-Version: 1.0 X-Received: by 10.60.175.195 with SMTP id cc3mr9211905oec.10.1419241490274; Mon, 22 Dec 2014 01:44:50 -0800 (PST) Received: by 10.76.153.130 with HTTP; Mon, 22 Dec 2014 01:44:50 -0800 (PST) In-Reply-To: References: <000001d01529$8bc1a2f0$a344e8d0$@arm.com> <1594949.Z5jBhjVPE5@polaris> Date: Mon, 22 Dec 2014 17:44:50 +0800 Message-ID: Subject: Re: [PATCH PR62151]Fix REG_DEAD note distribution issue by using right ELIM_I0/ELIM_I1 From: "Bin.Cheng" To: Eric Botcazou Cc: Bin Cheng , gcc-patches List , Jeff Law , Segher Boessenkool X-IsSubscribed: yes On Mon, Dec 22, 2014 at 3:54 PM, Bin.Cheng wrote: > On Sat, Dec 20, 2014 at 8:18 PM, Eric Botcazou wrote: >>> As described both in the PR and patch comments, this patch fixes PR62151 by >>> setting right value to ELIM_I0/ELIM_I1 when distributing REG_DEAD notes from >>> i0/i1. It is said that distribute_notes had caused many bugs in the past. >>> I think it still has bug in it, as noted in the PR. This patch doesn't >>> touch distribute_notes because we are in stage3 and I want to have more >>> discussion on it. >>> Bootstrap and test on x86_64. aarch64 is ongoing. So is it ok? >>> >>> 2014-12-11 Bin Cheng >>> >>> PR rtl-optimization/62151 >>> * combine.c (try_combine): Reset elim_i0 and elim_i1 when >>> distributing notes from i0notes or i1notes, this time don't >>> check whether newi2pat sets i1dest or i0dest. >> >> The reasoning looks correct to me and the patch is certainly safe so it's OK >> on principle, but I think that we should avoid the duplication of predicates. >> >> Can you move the computation of the alternative elim_i1 & elim_i0 up to where >> the original ones are computed along with the explanation of why we care about >> newi2pat only for notes that were on I3 and I2? Something like: >> >> /* Compute which registers we expect to eliminate. newi2pat may be setting >> either i3dest or i2dest, so we must check it. */ >> rtx elim_i2 = ((newi2pat && reg_set_p (i2dest, newi2pat)) >> || i2dest_in_i2src || i2dest_in_i1src || i2dest_in_i0src >> || !i2dest_killed >> ? 0 : i2dest); >> /* For I1 we need to compute both local elimination and global elimination >> because i1dest may be the same as i3dest, in which case newi2pat may be >> setting i1dest. */ >> rtx local_elim_i1 = (i1 == 0 || i1dest_in_i1src || i1dest_in_i0src >> || !i1dest_killed >> ? 0 : i1dest); >> rtx elim_i1 = (local_elim_i1 == 0 >> || (newi2pat && reg_set_p (i1dest, newi2pat)) >> ? 0 : i1dest); >> /* Likewise for I0. */ >> rtx local_elim_i0 = (i0 == 0 || i0dest_in_i0src >> || !i0dest_killed >> ? 0 : i0dest); >> rtx elim_i0 = (local_elim_i0 == 0 >> || (newi2pat && reg_set_p (i0dest, newi2pat)) >> ? 0 : i0dest); >> >> -- >> Eric Botcazou > > Hi Eric, > Thanks for reviewing. Here comes the revised patch. Bootstrap and > test on x86_64, is it OK? > > Thanks, > bin > > > 2014-12-22 Bin Cheng > > PR rtl-optimization/62151 > * combine.c (try_combine): New local variables local_elim_i1 > and local_elim_i0. Set elim_i1 and elim_i0 using the local > version variables. Distribute notes from i0notes or i1notes > using the local variavbles. > > gcc/testsuite/ChangeLog > 2014-12-22 Bin Cheng > > PR rtl-optimization/62151 > * gcc.c-torture/execute/pr62151.c: New test. Hmm, I further revised comment in the patch since in try_combine, i2 is always after i0/i1. The original comment is inaccurate about that. Thanks, bin Index: gcc/testsuite/gcc.c-torture/execute/pr62151.c =================================================================== --- gcc/testsuite/gcc.c-torture/execute/pr62151.c (revision 0) +++ gcc/testsuite/gcc.c-torture/execute/pr62151.c (revision 0) @@ -0,0 +1,41 @@ +/* PR rtl-optimization/62151 */ + +int a, c, d, e, f, g, h, i; +short b; + +int +fn1 () +{ + b = 0; + for (;;) + { + int j[2]; + j[f] = 0; + if (h) + d = 0; + else + { + for (; f; f++) + ; + for (a = 0; a < 1; a++) + for (;;) + { + i = b & ((b ^ 1) & 83647) ? b : b - 1; + g = 1 ? i : 0; + e = j[0]; + if (c) + break; + return 0; + } + } + } +} + +int +main () +{ + fn1 (); + if (g != -1) + __builtin_abort (); + return 0; +} Index: gcc/combine.c =================================================================== --- gcc/combine.c (revision 218855) +++ gcc/combine.c (working copy) @@ -4119,19 +4119,46 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn rtx midnotes = 0; int from_luid; /* Compute which registers we expect to eliminate. newi2pat may be setting - either i3dest or i2dest, so we must check it. Also, i1dest may be the - same as i3dest, in which case newi2pat may be setting i1dest. */ + either i3dest or i2dest, so we must check it. */ rtx elim_i2 = ((newi2pat && reg_set_p (i2dest, newi2pat)) || i2dest_in_i2src || i2dest_in_i1src || i2dest_in_i0src || !i2dest_killed ? 0 : i2dest); - rtx elim_i1 = (i1 == 0 || i1dest_in_i1src || i1dest_in_i0src + /* For i1, we need to compute both local elimination and global + elimination information with respect to newi2pat because i1dest + may be the same as i3dest, in which case newi2pat may be setting + i1dest. Global information is used when distributing REG_DEAD + note for i2 and i3, in which case it does matter if newi2pat sets + i1dest or not. + + Local information is used when distributing REG_DEAD note for i1, + in which case it doesn't matter if newi2pat sets i1dest or not. + See PR62151, if we have four insns combination: + i0: r0 <- i0src + i1: r1 <- i1src (using r0) + REG_DEAD (r0) + i2: r0 <- i2src (using r1) + i3: r3 <- i3src (using r0) + ix: using r0 + From i1's point of view, r0 is eliminated, no matter if it is set + by newi2pat or not. In other words, REG_DEAD info for r0 in i1 + should be discarded. + + Note local information only affects cases in forms like "I1->I2->I3", + "I0->I1->I2->I3" or "I0&I1->I2, I2->I3". For other cases like + "I0->I1, I1&I2->I3" or "I1&I2->I3", newi2pat won't set i1dest or + i0dest anyway. */ + rtx local_elim_i1 = (i1 == 0 || i1dest_in_i1src || i1dest_in_i0src + || !i1dest_killed + ? 0 : i1dest); + rtx elim_i1 = (local_elim_i1 == 0 || (newi2pat && reg_set_p (i1dest, newi2pat)) - || !i1dest_killed ? 0 : i1dest); - rtx elim_i0 = (i0 == 0 || i0dest_in_i0src + /* Same case as i1. */ + rtx local_elim_i0 = (i0 == 0 || i0dest_in_i0src || !i0dest_killed + ? 0 : i0dest); + rtx elim_i0 = (local_elim_i0 == 0 || (newi2pat && reg_set_p (i0dest, newi2pat)) - || !i0dest_killed ? 0 : i0dest); /* Get the old REG_NOTES and LOG_LINKS from all our insns and @@ -4300,10 +4327,10 @@ try_combine (rtx_insn *i3, rtx_insn *i2, rtx_insn elim_i2, elim_i1, elim_i0); if (i1notes) distribute_notes (i1notes, i1, i3, newi2pat ? i2 : NULL, - elim_i2, elim_i1, elim_i0); + elim_i2, local_elim_i1, local_elim_i0); if (i0notes) distribute_notes (i0notes, i0, i3, newi2pat ? i2 : NULL, - elim_i2, elim_i1, elim_i0); + elim_i2, elim_i1, local_elim_i0); if (midnotes) distribute_notes (midnotes, NULL, i3, newi2pat ? i2 : NULL, elim_i2, elim_i1, elim_i0);