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Mon, 15 Aug 2022 05:25:23 GMT Received: from b06cxnps3074.portsmouth.uk.ibm.com (d06relay09.portsmouth.uk.ibm.com [9.149.109.194]) by ppma05fra.de.ibm.com with ESMTP id 3hx3k8s78x-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 15 Aug 2022 05:25:22 +0000 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps3074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 27F5PKeG29032940 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 15 Aug 2022 05:25:20 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 786B8AE045; Mon, 15 Aug 2022 05:25:20 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AEF78AE051; Mon, 15 Aug 2022 05:25:19 +0000 (GMT) Received: from pike.rch.stglabs.ibm.com (unknown [9.5.12.127]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 15 Aug 2022 05:25:19 +0000 (GMT) To: gcc-patches@gcc.gnu.org Subject: [RFC]rs6000: split complicated constant to memory Date: Mon, 15 Aug 2022 13:25:19 +0800 Message-Id: <20220815052519.194582-1-guojiufu@linux.ibm.com> X-Mailer: git-send-email 2.17.1 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: YuTbz8JwI9t2NnDIj8upt_op42ZqKCRn X-Proofpoint-ORIG-GUID: Gfyjr6ySCQ42P1HTbK4kyL_UpzNFLcud 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=2022-08-15_03,2022-08-11_01,2022-06-22_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 impostorscore=0 bulkscore=0 priorityscore=1501 adultscore=0 spamscore=0 suspectscore=0 mlxscore=0 phishscore=0 malwarescore=0 lowpriorityscore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2207270000 definitions=main-2208150020 X-Spam-Status: No, score=-11.4 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, KAM_STOCKGEN, RCVD_IN_MSPIKE_H2, SPF_HELO_NONE, SPF_PASS, TXREP, T_SCC_BODY_TEXT_LINE 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-Patchwork-Original-From: Jiufu Guo via Gcc-patches From: Jiufu Guo Reply-To: Jiufu Guo Cc: dje.gcc@gmail.com, segher@kernel.crashing.org, linkw@gcc.gnu.org Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org Sender: "Gcc-patches" Hi, This patch tries to put the constant into constant pool if building the constant requires 3 or more instructions. But there is a concern: I'm wondering if this patch is really profitable. Because, as I tested, 1. for simple case, if instructions are not been run in parallel, loading constant from memory maybe faster; but 2. if there are some instructions could run in parallel, loading constant from memory are not win comparing with building constant. As below examples. For f1.c and f3.c, 'loading' constant would be acceptable in runtime aspect; for f2.c and f4.c, 'loading' constant are visibly slower. For real-world cases, both kinds of code sequences exist. So, I'm not sure if we need to push this patch. Run a lot of times (1000000000) below functions to check runtime. f1.c: long foo (long *arg, long*, long *) { *arg = 0x1234567800000000; } asm building constant: lis 10,0x1234 ori 10,10,0x5678 sldi 10,10,32 vs. asm loading addis 10,2,.LC0@toc@ha ld 10,.LC0@toc@l(10) The runtime between 'building' and 'loading' are similar: some times the 'building' is faster; sometimes 'loading' is faster. And the difference is slight. f2.c long foo (long *arg, long *arg2, long *arg3) { *arg = 0x1234567800000000; *arg2 = 0x7965234700000000; *arg3 = 0x4689123700000000; } asm building constant: lis 7,0x1234 lis 10,0x7965 lis 9,0x4689 ori 7,7,0x5678 ori 10,10,0x2347 ori 9,9,0x1237 sldi 7,7,32 sldi 10,10,32 sldi 9,9,32 vs. loading addis 7,2,.LC0@toc@ha addis 10,2,.LC1@toc@ha addis 9,2,.LC2@toc@ha ld 7,.LC0@toc@l(7) ld 10,.LC1@toc@l(10) ld 9,.LC2@toc@l(9) For this case, 'loading' is always slower than 'building' (>15%). f3.c long foo (long *arg, long *, long *) { *arg = 384307168202282325; } lis 10,0x555 ori 10,10,0x5555 sldi 10,10,32 oris 10,10,0x5555 ori 10,10,0x5555 For this case, 'building' (through 5 instructions) are slower, and 'loading' is faster ~5%; f4.c long foo (long *arg, long *arg2, long *arg3) { *arg = 384307168202282325; *arg2 = -6148914691236517205; *arg3 = 768614336404564651; } lis 7,0x555 lis 10,0xaaaa lis 9,0xaaa ori 7,7,0x5555 ori 10,10,0xaaaa ori 9,9,0xaaaa sldi 7,7,32 sldi 10,10,32 sldi 9,9,32 oris 7,7,0x5555 oris 10,10,0xaaaa oris 9,9,0xaaaa ori 7,7,0x5555 ori 10,10,0xaaab ori 9,9,0xaaab For this cases, since 'building' constant are parallel, 'loading' is slower: ~8%. On p10, 'loading'(through 'pld') is also slower >4%. BR, Jeff(Jiufu) --- gcc/config/rs6000/rs6000.cc | 14 ++++++++++++++ gcc/testsuite/gcc.target/powerpc/pr63281.c | 11 +++++++++++ 2 files changed, 25 insertions(+) create mode 100644 gcc/testsuite/gcc.target/powerpc/pr63281.c diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc index 4b727d2a500..3798e11bdbc 100644 --- a/gcc/config/rs6000/rs6000.cc +++ b/gcc/config/rs6000/rs6000.cc @@ -10098,6 +10098,20 @@ rs6000_emit_set_const (rtx dest, rtx source) c = ((c & 0xffffffff) ^ 0x80000000) - 0x80000000; emit_move_insn (lo, GEN_INT (c)); } + else if (base_reg_operand (dest, mode) + && num_insns_constant (source, mode) > 2) + { + rtx sym = force_const_mem (mode, source); + if (TARGET_TOC && SYMBOL_REF_P (XEXP (sym, 0)) + && use_toc_relative_ref (XEXP (sym, 0), mode)) + { + rtx toc = create_TOC_reference (XEXP (sym, 0), copy_rtx (dest)); + sym = gen_const_mem (mode, toc); + set_mem_alias_set (sym, get_TOC_alias_set ()); + } + + emit_insn (gen_rtx_SET (dest, sym)); + } else rs6000_emit_set_long_const (dest, c); break; diff --git a/gcc/testsuite/gcc.target/powerpc/pr63281.c b/gcc/testsuite/gcc.target/powerpc/pr63281.c new file mode 100644 index 00000000000..469a8f64400 --- /dev/null +++ b/gcc/testsuite/gcc.target/powerpc/pr63281.c @@ -0,0 +1,11 @@ +/* PR target/63281 */ +/* { dg-do compile { target lp64 } } */ +/* { dg-options "-O2 -std=c99" } */ + +void +foo (unsigned long long *a) +{ + *a = 0x020805006106003; +} + +/* { dg-final { scan-assembler-times {\mp?ld\M} 1 } } */