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 ED936394443A for ; Wed, 26 May 2021 03:00:06 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org ED936394443A Received: from pps.filterd (m0098399.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 14Q2YiVN049451; Tue, 25 May 2021 23:00:05 -0400 Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 38sdm9ggwq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 25 May 2021 23:00:05 -0400 Received: from m0098399.ppops.net (m0098399.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 14Q2qToL115613; Tue, 25 May 2021 23:00:05 -0400 Received: from ppma06ams.nl.ibm.com (66.31.33a9.ip4.static.sl-reverse.com [169.51.49.102]) by mx0a-001b2d01.pphosted.com with ESMTP id 38sdm9ggvf-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Tue, 25 May 2021 23:00:05 -0400 Received: from pps.filterd (ppma06ams.nl.ibm.com [127.0.0.1]) by ppma06ams.nl.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 14Q2sDqg007534; Wed, 26 May 2021 03:00:02 GMT Received: from b06cxnps4075.portsmouth.uk.ibm.com (d06relay12.portsmouth.uk.ibm.com [9.149.109.197]) by ppma06ams.nl.ibm.com with ESMTP id 38s1ukg8uq-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 26 May 2021 03:00:02 +0000 Received: from d06av24.portsmouth.uk.ibm.com (d06av24.portsmouth.uk.ibm.com [9.149.105.60]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 14Q3006B20840820 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Wed, 26 May 2021 03:00:00 GMT Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 7E4E44203F; Wed, 26 May 2021 03:00:00 +0000 (GMT) Received: from d06av24.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id B13CB42045; Wed, 26 May 2021 02:59:58 +0000 (GMT) Received: from kewenlins-mbp.cn.ibm.com (unknown [9.200.147.138]) by d06av24.portsmouth.uk.ibm.com (Postfix) with ESMTP; Wed, 26 May 2021 02:59:58 +0000 (GMT) Subject: [PATCH v2] rs6000: Add load density heuristic To: GCC Patches Cc: Bill Schmidt , David Edelsohn , Segher Boessenkool , Richard Biener References: <7b9f9bdf-1ed5-139b-de9c-511ee8454b85@linux.ibm.com> From: "Kewen.Lin" Message-ID: <3424a3d3-fa4e-16f9-89c6-0b07beec957d@linux.ibm.com> Date: Wed, 26 May 2021 10:59:57 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.10.0 In-Reply-To: <7b9f9bdf-1ed5-139b-de9c-511ee8454b85@linux.ibm.com> Content-Type: multipart/mixed; boundary="------------A1B16BC12EC2EE5FB543516B" Content-Language: en-US X-TM-AS-GCONF: 00 X-Proofpoint-GUID: qbq6VCBJobhLWHG0RRVmuaQr1U2x-iGA X-Proofpoint-ORIG-GUID: jzLcXMZDAFJLdUgVxmd80jt0fU342vmm X-Proofpoint-UnRewURL: 0 URL was un-rewritten MIME-Version: 1.0 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.761 definitions=2021-05-25_09:2021-05-25, 2021-05-25 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 adultscore=0 impostorscore=0 mlxscore=0 suspectscore=0 priorityscore=1501 bulkscore=0 lowpriorityscore=0 spamscore=0 phishscore=0 malwarescore=0 clxscore=1015 mlxlogscore=999 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2105260016 X-Spam-Status: No, score=-11.5 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_EF, GIT_PATCH_0, KAM_SHORT, RCVD_IN_DNSWL_NONE, RCVD_IN_MSPIKE_H3, RCVD_IN_MSPIKE_WL, SPF_HELO_NONE, SPF_PASS, TXREP autolearn=ham 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: Wed, 26 May 2021 03:00:09 -0000 This is a multi-part message in MIME format. --------------A1B16BC12EC2EE5FB543516B Content-Type: text/plain; charset=gbk Content-Transfer-Encoding: 7bit Hi, This is the updated version of patch to deal with the bwaves_r degradation due to vector construction fed by strided loads. As Richi's comments [1], this follows the similar idea to over price the vector construction fed by VMAT_ELEMENTWISE or VMAT_STRIDED_SLP. Instead of adding the extra cost on vector construction costing immediately, it firstly records how many loads and vectorized statements in the given loop, later in rs6000_density_test (called by finish_cost) it computes the load density ratio against all vectorized stmts, and check with the corresponding thresholds DENSITY_LOAD_NUM_THRESHOLD and DENSITY_LOAD_PCT_THRESHOLD, do the actual extra pricing if both thresholds are exceeded. Note that this new load density heuristic check is based on some fields in target cost which are updated as needed when scanning each add_stmt_cost entry, it's independent of the current function rs6000_density_test which requires to scan non_vect stmts. Since it's checking the load stmts count vs. all vectorized stmts, it's kind of density, so I put it in function rs6000_density_test. With the same reason to keep it independent, I didn't put it as an else arm of the current existing density threshold check hunk or before this hunk. In the investigation of -1.04% degradation from 526.blender_r on Power8, I noticed that the extra penalized cost 320 on one single vector construction with type V16QI is much exaggerated, which makes the final body cost unreliable, so this patch adds one maximum bound for the extra penalized cost for each vector construction statement. Bootstrapped/regtested on powerpc64le-linux-gnu P9. Full SPEC2017 performance evaluation on Power8/Power9 with option combinations: * -O2 -ftree-vectorize {,-fvect-cost-model=very-cheap} {,-ffast-math} * {-O3, -Ofast} {,-funroll-loops} bwaves_r degradations on P8/P9 have been fixed, nothing else remarkable was observed. Is it ok for trunk? [1] https://gcc.gnu.org/pipermail/gcc-patches/2021-May/570076.html BR, Kewen ----- gcc/ChangeLog: * config/rs6000/rs6000.c (struct rs6000_cost_data): New members nstmts, nloads and extra_ctor_cost. (rs6000_density_test): Add load density related heuristics and the checks, do extra costing on vector construction statements if need. (rs6000_init_cost): Init new members. (rs6000_update_target_cost_per_stmt): New function. (rs6000_add_stmt_cost): Factor vect_nonmem hunk out to function rs6000_update_target_cost_per_stmt and call it. --------------A1B16BC12EC2EE5FB543516B Content-Type: text/plain; charset=UTF-8; x-mac-type="0"; x-mac-creator="0"; name="ctor_extra_cost_v2.diff" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="ctor_extra_cost_v2.diff" diff --git a/gcc/config/rs6000/rs6000.c b/gcc/config/rs6000/rs6000.c index 83d29cbfac1..806c3335cbc 100644 --- a/gcc/config/rs6000/rs6000.c +++ b/gcc/config/rs6000/rs6000.c @@ -5231,6 +5231,12 @@ typedef struct _rs6000_cost_data { struct loop *loop_info; unsigned cost[3]; + /* Total number of vectorized stmts (loop only). */ + unsigned nstmts; + /* Total number of loads (loop only). */ + unsigned nloads; + /* Possible extra penalized cost on vector construction (loop only). */ + unsigned extra_ctor_cost; /* For each vectorized loop, this var holds TRUE iff a non-memory vector instruction is needed by the vectorization. */ bool vect_nonmem; @@ -5292,9 +5298,45 @@ rs6000_density_test (rs6000_cost_data *data) if (dump_enabled_p ()) dump_printf_loc (MSG_NOTE, vect_location, "density %d%%, cost %d exceeds threshold, penalizing " - "loop body cost by %d%%", density_pct, + "loop body cost by %d%%\n", density_pct, vec_cost + not_vec_cost, DENSITY_PENALTY); } + + /* Check if we need to penalize the body cost for latency and + execution resources bound from strided or elementwise loads + into a vector. */ + if (data->extra_ctor_cost > 0) + { + /* Threshold for load stmts percentage in all vectorized stmts. */ + const int DENSITY_LOAD_PCT_THRESHOLD = 45; + /* Threshold for total number of load stmts. */ + const int DENSITY_LOAD_NUM_THRESHOLD = 20; + + gcc_assert (data->nloads <= data->nstmts); + unsigned int load_pct = (data->nloads * 100) / (data->nstmts); + + /* It's likely to be bounded by latency and execution resources + from many scalar loads which are strided or elementwise loads + into a vector if both conditions below are found: + 1. there are many loads, it's easy to result in a long wait + for load units; + 2. load has a big proportion of all vectorized statements, + it's not easy to schedule other statements to spread among + the loads. + One typical case is the innermost loop of the hotspot of SPEC2017 + 503.bwaves_r without loop interchange. */ + if (data->nloads > DENSITY_LOAD_NUM_THRESHOLD + && load_pct > DENSITY_LOAD_PCT_THRESHOLD) + { + data->cost[vect_body] += data->extra_ctor_cost; + if (dump_enabled_p ()) + dump_printf_loc (MSG_NOTE, vect_location, + "Found %u loads and load pct. %u%% exceed " + "the threshold, penalizing loop body " + "cost by extra cost %u for ctor.\n", + data->nloads, load_pct, data->extra_ctor_cost); + } + } } /* Implement targetm.vectorize.init_cost. */ @@ -5308,6 +5350,9 @@ rs6000_init_cost (struct loop *loop_info, bool costing_for_scalar) data->cost[vect_body] = 0; data->cost[vect_epilogue] = 0; data->vect_nonmem = false; + data->nstmts = 0; + data->nloads = 0; + data->extra_ctor_cost = 0; data->costing_for_scalar = costing_for_scalar; return data; } @@ -5335,6 +5380,66 @@ rs6000_adjust_vect_cost_per_stmt (enum vect_cost_for_stmt kind, return 0; } +/* As a visitor function for each statement cost entry handled in + function add_stmt_cost, gather some information and update its + relevant fields in target cost accordingly. */ +static void +rs6000_update_target_cost_per_stmt (rs6000_cost_data *data, + enum vect_cost_for_stmt kind, + struct _stmt_vec_info *stmt_info, + enum vect_cost_model_location where, + int stmt_cost, unsigned int orig_count) +{ + + /* Check whether we're doing something other than just a copy loop. + Not all such loops may be profitably vectorized; see + rs6000_finish_cost. */ + if ((kind == vec_to_scalar || kind == vec_perm || kind == vec_promote_demote + || kind == vec_construct || kind == scalar_to_vec) + || (where == vect_body && kind == vector_stmt)) + data->vect_nonmem = true; + + /* Gather some information when we are costing the vector version for + the statements locate in a loop body. */ + if (!data->costing_for_scalar && data->loop_info && where == vect_body) + { + data->nstmts += orig_count; + + if (kind == scalar_load || kind == vector_load || kind == unaligned_load + || kind == vector_gather_load) + data->nloads += orig_count; + + /* If we have strided or elementwise loads into a vector, it's + possible to be bounded by latency and execution resources for + many scalar loads. Try to account for this by scaling the + construction cost by the number of elements involved, when + handling each matching statement we record the possible extra + penalized cost into target cost, in the end of costing for + the whole loop, we do the actual penalization once some load + density heuristics are satisfied. */ + if (kind == vec_construct && stmt_info + && STMT_VINFO_TYPE (stmt_info) == load_vec_info_type + && (STMT_VINFO_MEMORY_ACCESS_TYPE (stmt_info) == VMAT_ELEMENTWISE + || STMT_VINFO_MEMORY_ACCESS_TYPE (stmt_info) == VMAT_STRIDED_SLP)) + { + tree vectype = STMT_VINFO_VECTYPE (stmt_info); + unsigned int nunits = vect_nunits_for_cost (vectype); + unsigned int extra_cost = nunits * stmt_cost; + /* As function rs6000_builtin_vectorization_cost shows, we have + priced much on V16QI/V8HI vector construction as their units, + if we penalize them with nunits * stmt_cost, it can result in + a unreliable body cost, eg: for V16QI on Power8, stmt_cost is + 20 and nunits is 16, the extra cost is 320 which looks much + exaggerated. So let's use one maximum bound for the extra + penalized cost for vector construction here. */ + const unsigned int MAX_PENALIZED_COST_FOR_CTOR = 12; + if (extra_cost > MAX_PENALIZED_COST_FOR_CTOR) + extra_cost = MAX_PENALIZED_COST_FOR_CTOR; + data->extra_ctor_cost += extra_cost; + } + } +} + /* Implement targetm.vectorize.add_stmt_cost. */ static unsigned @@ -5354,6 +5459,7 @@ rs6000_add_stmt_cost (class vec_info *vinfo, void *data, int count, /* Statements in an inner loop relative to the loop being vectorized are weighted more heavily. The value here is arbitrary and could potentially be improved with analysis. */ + unsigned int orig_count = count; if (where == vect_body && stmt_info && stmt_in_inner_loop_p (vinfo, stmt_info)) { @@ -5365,14 +5471,8 @@ rs6000_add_stmt_cost (class vec_info *vinfo, void *data, int count, retval = (unsigned) (count * stmt_cost); cost_data->cost[where] += retval; - /* Check whether we're doing something other than just a copy loop. - Not all such loops may be profitably vectorized; see - rs6000_finish_cost. */ - if ((kind == vec_to_scalar || kind == vec_perm - || kind == vec_promote_demote || kind == vec_construct - || kind == scalar_to_vec) - || (where == vect_body && kind == vector_stmt)) - cost_data->vect_nonmem = true; + rs6000_update_target_cost_per_stmt (cost_data, kind, stmt_info, where, + stmt_cost, orig_count); } return retval; --------------A1B16BC12EC2EE5FB543516B--