From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx0a-001b2d01.pphosted.com (mx0b-001b2d01.pphosted.com [148.163.158.5]) by sourceware.org (Postfix) with ESMTPS id B83033864812 for ; Fri, 25 Jun 2021 16:09:29 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org B83033864812 Received: from pps.filterd (m0098416.ppops.net [127.0.0.1]) by mx0b-001b2d01.pphosted.com (8.16.0.43/8.16.0.43) with SMTP id 15PG3r6Y053441; Fri, 25 Jun 2021 12:09:27 -0400 Received: from ppma03ams.nl.ibm.com (62.31.33a9.ip4.static.sl-reverse.com [169.51.49.98]) by mx0b-001b2d01.pphosted.com with ESMTP id 39dh5yk84c-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 25 Jun 2021 12:09:27 -0400 Received: from pps.filterd (ppma03ams.nl.ibm.com [127.0.0.1]) by ppma03ams.nl.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 15PG7eAs032253; Fri, 25 Jun 2021 16:09:25 GMT Received: from b06avi18878370.portsmouth.uk.ibm.com (b06avi18878370.portsmouth.uk.ibm.com [9.149.26.194]) by ppma03ams.nl.ibm.com with ESMTP id 399878b4ce-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 25 Jun 2021 16:09:25 +0000 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06avi18878370.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 15PG7tll18678080 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 25 Jun 2021 16:07:55 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6409AAE06F; Fri, 25 Jun 2021 16:09:22 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 240D1AE067; Fri, 25 Jun 2021 16:09:22 +0000 (GMT) Received: from li-926bd7cc-2dd1-11b2-a85c-f6adc0f5efec.ibm.com (unknown [9.171.46.33]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 25 Jun 2021 16:09:22 +0000 (GMT) From: Robin Dapp To: gcc-patches@gcc.gnu.org, richard.sandiford@arm.com Subject: [PATCH 5/7] ifcvt: Try re-using CC for conditional moves. Date: Fri, 25 Jun 2021 18:09:03 +0200 Message-Id: <20210625160905.23786-6-rdapp@linux.ibm.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20210625160905.23786-1-rdapp@linux.ibm.com> References: <20210625160905.23786-1-rdapp@linux.ibm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: ziQd7VpZuFr31GQxcSnfpkj9c-nOx6if X-Proofpoint-GUID: ziQd7VpZuFr31GQxcSnfpkj9c-nOx6if X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.391, 18.0.790 definitions=2021-06-25_05:2021-06-25, 2021-06-25 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 impostorscore=0 phishscore=0 malwarescore=0 mlxlogscore=999 clxscore=1015 adultscore=0 spamscore=0 mlxscore=0 priorityscore=1501 suspectscore=0 bulkscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2104190000 definitions=main-2106250094 X-Spam-Status: No, score=-11.4 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=3.4.2 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, 25 Jun 2021 16:09:31 -0000 Following up on the previous patch, this patch makes noce_convert_multiple emit two cmov sequences: The same one as before and a second one that tries to re-use the existing CC. Then their costs are compared and the cheaper one is selected. --- gcc/ifcvt.c | 94 ++++++++++++++++++++++++++++++++++++++++++++++++----- 1 file changed, 86 insertions(+), 8 deletions(-) diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c index c5b8641e2aa..55405ce9ef7 100644 --- a/gcc/ifcvt.c +++ b/gcc/ifcvt.c @@ -3142,6 +3142,47 @@ bb_valid_for_noce_process_p (basic_block test_bb, rtx cond, return false; } +/* Helper function to emit a cmov sequence. */ + +static rtx_insn* +try_emit_cmove_seq (struct noce_if_info *if_info, rtx temp, + rtx cond, rtx target, + rtx new_val, rtx old_val, bool need_cmov, + unsigned *cost, rtx *temp_dest, + rtx cc_cmp = NULL, rtx rev_cc_cmp = NULL) +{ + rtx_insn *seq = NULL; + *cost = 0; + + rtx x = XEXP (cond, 0); + rtx y = XEXP (cond, 1); + rtx_code cond_code = GET_CODE (cond); + + start_sequence (); + + if (need_cmov) + *temp_dest = noce_emit_cmove (if_info, temp, cond_code, + x, y, new_val, old_val, cc_cmp, rev_cc_cmp); + else + { + *temp_dest = target; + if (if_info->then_else_reversed) + noce_emit_move_insn (target, old_val); + else + noce_emit_move_insn (target, new_val); + } + + if (*temp_dest != NULL_RTX) + { + seq = get_insns (); + *cost = seq_cost (seq, if_info->speed_p); + } + + end_sequence (); + + return seq; +} + /* We have something like: if (x > y) @@ -3199,7 +3240,9 @@ noce_convert_multiple_sets (struct noce_if_info *if_info) rtx cond = noce_get_condition (jump, &cond_earliest, false); rtx x = XEXP (cond, 0); rtx y = XEXP (cond, 1); - rtx_code cond_code = GET_CODE (cond); + + rtx cc_cmp = cond_exec_get_condition (jump); + rtx rev_cc_cmp = noce_get_condition (jump, &cond_earliest, true); /* The true targets for a conditional move. */ auto_vec targets; @@ -3301,18 +3344,52 @@ noce_convert_multiple_sets (struct noce_if_info *if_info) old_val = lowpart_subreg (dst_mode, old_val, src_mode); } - /* Actually emit the conditional move. */ - rtx temp_dest = noce_emit_cmove (if_info, temp, cond_code, - x, y, new_val, old_val); + /* Try emitting a conditional move passing the backend the + canonicalized comparison. The backend is then able to + recognize expressions like - /* If we failed to expand the conditional move, drop out and don't - try to continue. */ - if (temp_dest == NULL_RTX) + if (x > y) + y = x; + + as min/max emit an insn, accordingly. + We will still emit a superfluous CC comparison before the + min/max, though, which complicates costing. */ + unsigned cost1 = 0, cost2 = 0; + rtx_insn *seq, *seq1, *seq2; + rtx temp_dest = NULL_RTX, temp_dest1 = NULL_RTX, temp_dest2 = NULL_RTX; + + seq1 = try_emit_cmove_seq (if_info, temp, cond, target, + new_val, old_val, need_cmov, &cost1, &temp_dest1); + + /* Here, we try to pass the backend a non-canonicalized cc comparison + as well. This allows the backend to emit a cmov directly without + creating an additional compare for each. If successful, costing + is easier and this sequence is usually preferred. */ + seq2 = try_emit_cmove_seq (if_info, target, cond, target, + new_val, old_val, need_cmov, &cost2, &temp_dest2, + cc_cmp, rev_cc_cmp); + + /* Check which version is less expensive. */ + if (seq1 != NULL_RTX && cost1 <= cost2) + { + seq = seq1; + temp_dest = temp_dest1; + } + else if (seq2 != NULL_RTX) + { + seq = seq2; + temp_dest = temp_dest2; + } + else { + /* Nothing worked, bail out. */ end_sequence (); return FALSE; } + /* End the sub sequence and emit to the main sequence. */ + emit_insn (seq); + /* Bookkeeping. */ count++; targets.safe_push (target); @@ -3326,7 +3403,8 @@ noce_convert_multiple_sets (struct noce_if_info *if_info) /* Now fixup the assignments. */ for (int i = 0; i < count; i++) - noce_emit_move_insn (targets[i], temporaries[i]); + if (targets[i] != temporaries[i]) + noce_emit_move_insn (targets[i], temporaries[i]); /* Actually emit the sequence if it isn't too expensive. */ rtx_insn *seq = get_insns (); -- 2.31.1