From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from smtp-out2.suse.de (smtp-out2.suse.de [IPv6:2001:67c:2178:6::1d]) by sourceware.org (Postfix) with ESMTPS id 5FCE23858290 for ; Tue, 23 Aug 2022 12:16:34 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.4.1 sourceware.org 5FCE23858290 Received: from relay2.suse.de (relay2.suse.de [149.44.160.134]) by smtp-out2.suse.de (Postfix) with ESMTP id E3F3E1F86C; Tue, 23 Aug 2022 12:16:32 +0000 (UTC) Received: from wotan.suse.de (wotan.suse.de [10.160.0.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by relay2.suse.de (Postfix) with ESMTPS id D89B42C141; Tue, 23 Aug 2022 12:16:32 +0000 (UTC) Date: Tue, 23 Aug 2022 12:16:32 +0000 (UTC) From: Richard Biener To: gcc-patches@gcc.gnu.org Subject: [PATCH] Speedup path discovery in predicate::use_cannot_happen User-Agent: Alpine 2.22 (LSU 394 2020-01-19) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-Spam-Status: No, score=-10.6 required=5.0 tests=BAYES_00, DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, DKIM_VALID_EF, GIT_PATCH_0, MISSING_MID, 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-List-Received-Date: Tue, 23 Aug 2022 12:16:36 -0000 Message-ID: <20220823121632.CyOu77xSFnrwl0V3CyPQIw2b53IvBXDd41Oy4wgwtVg@z> The following reverts a hunk from r8-5789-g11ef0b22d68cd1 that made compute_control_dep_chain start from function entry rather than the immediate dominator of the source block of the edge with the undefined value on the PHI node. Reverting at that point does not reveal any testsuite FAIL, in particular the added testcase still passes. The following adjusts this to the other function that computes predicates that hold on the PHI incoming edges with undefined values, predicate::init_from_phi_def, which starts at the immediate dominator of the PHI. That's much less likely to run into the CFG walking limit. Bootstrapped and tested on x86_64-unknown-linux-gnu. Aldy - you did this change, do you remember anything here? In fact the whole thing that's now called predicate::use_cannot_happen seems to be redundant - the two testcases attributed to its history do not fail when that's disabled, nor did they fail when it was introduced. In principle whats now called predicate::superset_of should cover this (but different implementation limits might apply). OK? * gimple-predicate-analysis.cc (predicate::use_cannot_happen): Start the compute_control_dep_chain walk from the immediate dominator of the PHI. --- gcc/gimple-predicate-analysis.cc | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/gcc/gimple-predicate-analysis.cc b/gcc/gimple-predicate-analysis.cc index a4291657d0b..ea81daacd4f 100644 --- a/gcc/gimple-predicate-analysis.cc +++ b/gcc/gimple-predicate-analysis.cc @@ -1293,6 +1293,12 @@ predicate::use_cannot_happen (gphi *phi, unsigned opnds) use_guard = &phi_use_guard_intersection; } + basic_block phi_bb = gimple_bb (phi); + /* Find the closest dominating bb to be the control dependence root. */ + basic_block cd_root = get_immediate_dominator (CDI_DOMINATORS, phi_bb); + if (!cd_root) + return false; + /* Look for the control dependencies of all the interesting operands and build guard predicates describing them. */ unsigned n = gimple_phi_num_args (phi); @@ -1308,7 +1314,7 @@ predicate::use_cannot_happen (gphi *phi, unsigned opnds) unsigned num_calls = 0; /* Build the control dependency chain for the PHI argument... */ - if (!compute_control_dep_chain (ENTRY_BLOCK_PTR_FOR_FN (cfun), + if (!compute_control_dep_chain (cd_root, e->src, dep_chains, &num_chains, cur_chain, &num_calls)) { -- 2.35.3