From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by sourceware.org (Postfix) with ESMTPS id BF51B3857BB2; Fri, 15 Jul 2022 12:53:52 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org BF51B3857BB2 Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.17.1.5/8.17.1.5) with ESMTP id 26FCCF5S010617; Fri, 15 Jul 2022 12:53:49 GMT Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3hb81js2j9-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 15 Jul 2022 12:53:49 +0000 Received: from m0098399.ppops.net (m0098399.ppops.net [127.0.0.1]) by pps.reinject (8.17.1.5/8.17.1.5) with ESMTP id 26FCldUe031332; Fri, 15 Jul 2022 12:53:48 GMT Received: from ppma04dal.us.ibm.com (7a.29.35a9.ip4.static.sl-reverse.com [169.53.41.122]) by mx0a-001b2d01.pphosted.com (PPS) with ESMTPS id 3hb81js2hv-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 15 Jul 2022 12:53:48 +0000 Received: from pps.filterd (ppma04dal.us.ibm.com [127.0.0.1]) by ppma04dal.us.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 26FCoP6m013685; Fri, 15 Jul 2022 12:53:47 GMT Received: from b01cxnp23033.gho.pok.ibm.com (b01cxnp23033.gho.pok.ibm.com [9.57.198.28]) by ppma04dal.us.ibm.com with ESMTP id 3h9e0565bp-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 15 Jul 2022 12:53:47 +0000 Received: from b01ledav005.gho.pok.ibm.com (b01ledav005.gho.pok.ibm.com [9.57.199.110]) by b01cxnp23033.gho.pok.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 26FCrk8R48955684 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 15 Jul 2022 12:53:46 GMT Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id ADA61AE062; Fri, 15 Jul 2022 12:53:46 +0000 (GMT) Received: from b01ledav005.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 63DADAE05C; Fri, 15 Jul 2022 12:53:46 +0000 (GMT) Received: from pike (unknown [9.5.12.127]) by b01ledav005.gho.pok.ibm.com (Postfix) with ESMTPS; Fri, 15 Jul 2022 12:53:46 +0000 (GMT) From: Jiufu Guo To: "Kewen.Lin" Cc: segher@kernel.crashing.org, dje.gcc@gmail.com, linkw@gcc.gnu.org, gcc-patches@gcc.gnu.org Subject: Re: [PATCH] HIGH part of symbol ref is invalid for constant pool References: <20220704065831.55961-1-guojiufu@linux.ibm.com> <248b65bd-5a2a-8315-1b18-3c8d0606643f@linux.ibm.com> Date: Fri, 15 Jul 2022 20:53:37 +0800 In-Reply-To: <248b65bd-5a2a-8315-1b18-3c8d0606643f@linux.ibm.com> (Kewen Lin's message of "Thu, 14 Jul 2022 10:54:23 +0800") Message-ID: <7etu7i4jvy.fsf@pike.rch.stglabs.ibm.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.2 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-GUID: byPb2xg_8xz96vUB1rU0fRUGjCoigluX X-Proofpoint-ORIG-GUID: UzN0GOVzc72Fxo-FmOdK7G2bM746sYAW X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.883,Hydra:6.0.517,FMLib:17.11.122.1 definitions=2022-07-15_05,2022-07-15_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 suspectscore=0 mlxscore=0 mlxlogscore=999 clxscore=1015 phishscore=0 bulkscore=0 spamscore=0 impostorscore=0 malwarescore=0 lowpriorityscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2206140000 definitions=main-2207150055 X-Spam-Status: No, score=-12.2 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_EF, GIT_PATCH_0, RCVD_IN_MSPIKE_H2, 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 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, 15 Jul 2022 12:53:54 -0000 "Kewen.Lin" writes: > Hi Jeff, > > Thanks for the patch, one question is inlined below. > > on 2022/7/4 14:58, Jiufu Guo wrote: >> The high part of the symbol address is invalid for the constant pool. In >> function rs6000_cannot_force_const_mem, we already return true for >> "HIGH with UNSPEC" rtx. During debug GCC, I found that >> rs6000_cannot_force_const_mem is called for some other HIGH code rtx >> expressions which also indicate the high part of a symbol_ref. >> For example: >> (high:DI (const:DI (plus:DI (symbol_ref:DI ("xx") (const_int 12 [0xc]))))) >> (high:DI (symbol_ref:DI ("var_1")..))) >> >> In the below case, this kind of rtx could occur in the middle of optimizations >> pass but was not dumped to a file. So, no test case is attached to this >> patch. >> > > Could you help to expand this more on how it affects some tree-optimization pass? > I guess some tree-opt will expand gimple expression to rtx, evaluate the cost > or similar and make some decision basing on it. If that is the case, you probably > can construct one test case to show that: without this patch, the evaluated cost > or similar looks off, the optimization decision is sub-optimal; with this patch, > the optimization result is expected. Hi Kewen, Thanks a lot for your comments! >From my investigations, I find some cases for which rs6000_cannot_force_const_mem is called on "HIGH code" rtx which is not UNSPEC sub-code. The code "decSetCoeff" is an example. In the middle of "combine" pass, function "recog_for_combine" invokes "force_const_mem", and the invoking could fail. src = force_const_mem (mode, src); if (src) { SUBST (SET_SRC (pat), src); changed = true; } Here, the rtx "(high:DI (unspec:DI [(symbol_ref" is the argument for the example code "decSetCoeff". I also tried to see if other passes(GIMPLE) could hit this kind cases, but did not find. BR, Jiufu(Jeff) > > BR, > Kewen > > >> extern const unsigned int __decPOWERS[10]; >> void >> decSetCoeff (int *residue, const unsigned int *up) >> { >> unsigned int half = (unsigned int) __decPOWERS1[3] >> 1; >> >> if (*up >= half) >> *residue = 7; >> >> return; >> } >> >> This patch updates rs6000_cannot_force_const_mem to return true for >> rtx with HIGH code. >> >> >> Bootstrapped and regtested on ppc64le and ppc64. >> Is it ok for trunk? >> >> BR, >> Jiufu Guo >> >> >> gcc/ChangeLog: >> >> * config/rs6000/rs6000.cc (rs6000_cannot_force_const_mem): >> Return true for HIGH code rtx. >> >> --- >> gcc/config/rs6000/rs6000.cc | 7 +++++-- >> 1 file changed, 5 insertions(+), 2 deletions(-) >> >> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc >> index 3ff16b8ae04..c2b10669627 100644 >> --- a/gcc/config/rs6000/rs6000.cc >> +++ b/gcc/config/rs6000/rs6000.cc >> @@ -9707,8 +9707,11 @@ rs6000_init_stack_protect_guard (void) >> static bool >> rs6000_cannot_force_const_mem (machine_mode mode ATTRIBUTE_UNUSED, rtx x) >> { >> - if (GET_CODE (x) == HIGH >> - && GET_CODE (XEXP (x, 0)) == UNSPEC) >> + /* High part of a symbol ref/address can not be put into constant pool. e.g. >> + (high:DI (symbol_ref:DI ("var")..)) or >> + (high:DI (unspec:DI [(symbol_ref/u:DI ("*.LC0")..) >> + (high:DI (const:DI (plus:DI (symbol_ref:DI ("xx")) (const_int 12)))). */ >> + if (GET_CODE (x) == HIGH) >> return true; >> >> /* A TLS symbol in the TOC cannot contain a sum. */