From patchwork Mon Dec 6 18:43:50 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Robin Dapp X-Patchwork-Id: 48551 Return-Path: X-Original-To: patchwork@sourceware.org Delivered-To: patchwork@sourceware.org Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id 6BECF385843B for ; Mon, 6 Dec 2021 18:52:15 +0000 (GMT) DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 6BECF385843B DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gcc.gnu.org; s=default; t=1638816735; bh=xhtZzBZxejbV/5h9CuJZSR+qBAYxPGFBxremizatopQ=; h=To:Subject:Date:In-Reply-To:References:List-Id:List-Unsubscribe: List-Archive:List-Post:List-Help:List-Subscribe:From:Reply-To: From; b=yrHLZLmMiON5c/wK9a9nzhrIRhQVrCsQ+tZSv4X7/Bzegd2ClpNJ13otXerDJkPZN M0sT4EkPQOORSQ0AE/zC/+aQxH8Cp6txic+x7FDcemDWSz9I8K7Ym0dOXQ7X3m+j9G oNLzgEradyCm+z34ilaXIk+F879YJE4BMX6zW9SQ= X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) by sourceware.org (Postfix) with ESMTPS id 8D84B3858414 for ; Mon, 6 Dec 2021 18:46:28 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 8D84B3858414 Received: from pps.filterd (m0187473.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 1B6INDxL027507; Mon, 6 Dec 2021 18:46:24 GMT Received: from ppma03fra.de.ibm.com (6b.4a.5195.ip4.static.sl-reverse.com [149.81.74.107]) by mx0a-001b2d01.pphosted.com with ESMTP id 3csqrkgdx8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 06 Dec 2021 18:46:24 +0000 Received: from pps.filterd (ppma03fra.de.ibm.com [127.0.0.1]) by ppma03fra.de.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 1B6IhtPN027625; Mon, 6 Dec 2021 18:46:22 GMT Received: from b06cxnps4076.portsmouth.uk.ibm.com (d06relay13.portsmouth.uk.ibm.com [9.149.109.198]) by ppma03fra.de.ibm.com with ESMTP id 3cqyy96w78-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 06 Dec 2021 18:46:22 +0000 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 1B6IkIKo29098454 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 6 Dec 2021 18:46:18 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A1C4711C04C; Mon, 6 Dec 2021 18:46:18 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 6DFA511C052; Mon, 6 Dec 2021 18:46:18 +0000 (GMT) Received: from li-926bd7cc-2dd1-11b2-a85c-f6adc0f5efec.ibm.com (unknown [9.171.69.25]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Mon, 6 Dec 2021 18:46:18 +0000 (GMT) To: gcc-patches@gcc.gnu.org, richard.sandiford@arm.com Subject: [PATCH v3 5/7] ifcvt: Try re-using CC for conditional moves. Date: Mon, 6 Dec 2021 19:43:50 +0100 Message-Id: <20211206184352.42264-6-rdapp@linux.ibm.com> X-Mailer: git-send-email 2.27.0 In-Reply-To: <20211206184352.42264-1-rdapp@linux.ibm.com> References: <20211206184352.42264-1-rdapp@linux.ibm.com> MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-ORIG-GUID: iL1atfFL9bu6ErFv4Nhpzlx9laNzXjgr X-Proofpoint-GUID: iL1atfFL9bu6ErFv4Nhpzlx9laNzXjgr X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.790,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2021-12-06_07,2021-12-06_02,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 clxscore=1015 lowpriorityscore=0 phishscore=0 mlxlogscore=999 priorityscore=1501 malwarescore=0 suspectscore=0 adultscore=0 bulkscore=0 spamscore=0 mlxscore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2110150000 definitions=main-2112060111 X-Spam-Status: No, score=-11.9 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=3.4.4 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) 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: Robin Dapp via Gcc-patches From: Robin Dapp Reply-To: Robin Dapp Errors-To: gcc-patches-bounces+patchwork=sourceware.org@gcc.gnu.org Sender: "Gcc-patches" 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 | 112 +++++++++++++++++++++++++++++++++++++++++----------- 1 file changed, 88 insertions(+), 24 deletions(-) diff --git a/gcc/ifcvt.c b/gcc/ifcvt.c index 3e78e1bb03d..d1e7db1ee27 100644 --- a/gcc/ifcvt.c +++ b/gcc/ifcvt.c @@ -83,7 +83,7 @@ static rtx_insn *last_active_insn (basic_block, int); static rtx_insn *find_active_insn_before (basic_block, rtx_insn *); static rtx_insn *find_active_insn_after (basic_block, rtx_insn *); static basic_block block_fallthru (basic_block); -static rtx cond_exec_get_condition (rtx_insn *); +static rtx cond_exec_get_condition (rtx_insn *, bool); static rtx noce_get_condition (rtx_insn *, rtx_insn **, bool); static int noce_operand_ok (const_rtx); static void merge_if_block (ce_if_block *); @@ -427,7 +427,7 @@ cond_exec_process_insns (ce_if_block *ce_info ATTRIBUTE_UNUSED, /* Return the condition for a jump. Do not do any special processing. */ static rtx -cond_exec_get_condition (rtx_insn *jump) +cond_exec_get_condition (rtx_insn *jump, bool get_reversed = false) { rtx test_if, cond; @@ -439,8 +439,9 @@ cond_exec_get_condition (rtx_insn *jump) /* If this branches to JUMP_LABEL when the condition is false, reverse the condition. */ - if (GET_CODE (XEXP (test_if, 2)) == LABEL_REF - && label_ref_label (XEXP (test_if, 2)) == JUMP_LABEL (jump)) + if (get_reversed || (GET_CODE (XEXP (test_if, 2)) == LABEL_REF + && label_ref_label (XEXP (test_if, 2)) + == JUMP_LABEL (jump))) { enum rtx_code rev = reversed_comparison_code (cond, jump); if (rev == UNKNOWN) @@ -3146,6 +3147,46 @@ 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 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 = temp; + if (if_info->then_else_reversed) + noce_emit_move_insn (temp, old_val); + else + noce_emit_move_insn (temp, 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) @@ -3203,7 +3244,9 @@ 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 = cond_exec_get_condition (jump, /* get_reversed */ true); /* The true targets for a conditional move. */ auto_vec targets; @@ -3317,31 +3360,51 @@ noce_convert_multiple_sets (struct noce_if_info *if_info) old_val = lowpart_subreg (dst_mode, old_val, src_mode); } - rtx temp_dest = NULL_RTX; + /* Try emitting a conditional move passing the backend the + canonicalized comparison. The backend is then able to + recognize expressions like - if (need_cmov) + if (x > y) + y = x; + + as min/max and emit an insn, accordingly. */ + 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, + 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, + 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 || seq2 == NULL_RTX)) { - /* Actually emit the conditional move. */ - temp_dest = noce_emit_cmove (if_info, temp, cond_code, - x, y, new_val, old_val); - - /* If we failed to expand the conditional move, drop out and don't - try to continue. */ - if (temp_dest == NULL_RTX) - { - end_sequence (); - return FALSE; - } + seq = seq1; + temp_dest = temp_dest1; + } + else if (seq2 != NULL_RTX) + { + seq = seq2; + temp_dest = temp_dest2; } else { - if (if_info->then_else_reversed) - noce_emit_move_insn (temp, old_val); - else - noce_emit_move_insn (temp, new_val); - temp_dest = temp; + /* 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); @@ -3355,7 +3418,8 @@ 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 ();