From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mengyan1223.wang (mengyan1223.wang [89.208.246.23]) by sourceware.org (Postfix) with ESMTPS id 4DF86385781B for ; Fri, 12 Feb 2021 14:17:38 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 4DF86385781B Received: from [192.168.0.103] (unknown [120.208.101.154]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange ECDHE (P-256) server-signature ECDSA (P-384) server-digest SHA384) (Client did not present a certificate) (Authenticated sender: xry111@mengyan1223.wang) by mengyan1223.wang (Postfix) with ESMTPSA id DE031663B8; Fri, 12 Feb 2021 09:17:35 -0500 (EST) Message-ID: Subject: Re: [PATCH] MIPS: Fix PR target/98491 (ChangeLog) From: Xi Ruoyao To: Jeff Law , Jakub Jelinek Cc: gcc-patches@gcc.gnu.org, Robert Suchanek Date: Fri, 12 Feb 2021 22:17:32 +0800 In-Reply-To: References: <4df733093ede4a3cc5dcb2688dcc9a2e5be4b721.camel@mengyan1223.wang> <184fa89ee34af9c3b13e99513a10aed1bd7c88af.camel@mengyan1223.wang> <20210104210018.GD725145@tucnak> <7825bdca-1a9a-90dc-671f-1dda98e1f5f4@redhat.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.38.3 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spam-Status: No, score=-3030.2 required=5.0 tests=BAYES_00, BODY_8BITS, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, JMQ_SPF_NEUTRAL, SPF_HELO_PASS, SPF_PASS, TXREP autolearn=no autolearn_force=no version=3.4.2 X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on server2.sourceware.org X-BeenThere: gcc-patches@gcc.gnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Gcc-patches mailing list List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 12 Feb 2021 14:17:41 -0000 On 2021-01-11 01:01 +0800, Xi Ruoyao wrote: > Hi Jeff and Jakub, > > On 2021-01-04 14:19 -0700, Jeff Law wrote: > > On 1/4/21 2:00 PM, Jakub Jelinek wrote: > > > On Mon, Jan 04, 2021 at 01:51:59PM -0700, Jeff Law via Gcc-patches wrote: > > > > > Sorry, I forgot to include the ChangeLog: > > > > > > > > > >     gcc/ChangeLog: > > > > >     > > > > >     2020-12-31  Xi Ruoyao > > > > >     > > > > >             PR target/98491 > > > > >             * config/mips/mips.c (mips_symbol_insns): Do not use > > > > >               MSA_SUPPORTED_MODE_P if mode is MAX_MACHINE_MODE. > > > > So I absolutely agree the current code is wrong as it does an out of > > > > bounds array access. > > > > > > > > > > > > Would it be better to instead to change MSA_SUPPORTED_MODE_P to evaluate > > > > to zero if MODE is MAX_MACHINE_MODE?  That would protect all the uses of > > > > MSA_SUPPORTED_MODE_P.    Something like this perhaps? > > > But MAX_MACHINE_MODE is the one past last valid mode, I'm not aware of > > > any target that would protect all macros that deal with modes that way. > > > > > > So, perhaps best would be stop using the MAX_MACHINE_MODE as magic value > > > for that function and instead use say VOIDmode that shouldn't normally > > > appear either? > > I think we have to allow VOIDmode because constants don't necessarily > > have modes.   And I certainly agree that using MAX_MACHINE_MODE like > > this is ugly and error prone (as we can see from the BZ). > > > > I also couldn't convince myself that the code and comments were actually > > consistent, particularly for MSA targets which the comment claims can > > never handle constants for ld/st (and thus should be returning 0 for > > MAX_MACHINE_MODE).  Though maybe mips_symbol_insns_1 ultimately handles > > that correctly. > > > > > > > > > > But I don't really see anything wrong on the mips_symbol_insns above > > > change either. > > Me neither.  I'm just questioning if bullet-proofing in the > > MSA_SUPPORTED_MODE_P would be a better option.  While I've worked in the > > MIPS port in the past, I don't really have any significannt experience > > with the MSA support. > > I can't understand the comment either.  To me it looks like it's possible to > remove this "if (MSA_SUPPORTED_P (mode)) return 0;" > > CC Robert to get some help. Happy new lunar year folks. I found a newer email address of Robert. Hope it is still being used. Could someone update MAINTAINERS file by the way? -- Xi Ruoyao School of Aerospace Science and Technology, Xidian University