From patchwork Fri Aug 7 21:51:04 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Segher Boessenkool X-Patchwork-Id: 1342414 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=gcc.gnu.org (client-ip=8.43.85.97; helo=sourceware.org; envelope-from=gcc-patches-bounces@gcc.gnu.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Received: from sourceware.org (server2.sourceware.org [8.43.85.97]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id 4BNfFG0wZlz9sRK for ; Sat, 8 Aug 2020 07:51:12 +1000 (AEST) Received: from server2.sourceware.org (localhost [IPv6:::1]) by sourceware.org (Postfix) with ESMTP id E42153857C4E; Fri, 7 Aug 2020 21:51:08 +0000 (GMT) X-Original-To: gcc-patches@gcc.gnu.org Delivered-To: gcc-patches@gcc.gnu.org Received: from gcc1-power7.osuosl.org (gcc1-power7.osuosl.org [140.211.15.137]) by sourceware.org (Postfix) with ESMTP id 9B1963858D35 for ; Fri, 7 Aug 2020 21:51:06 +0000 (GMT) DMARC-Filter: OpenDMARC Filter v1.3.2 sourceware.org 9B1963858D35 Authentication-Results: sourceware.org; dmarc=none (p=none dis=none) header.from=kernel.crashing.org Authentication-Results: sourceware.org; spf=none smtp.mailfrom=segher@gcc1-power7.osuosl.org Received: by gcc1-power7.osuosl.org (Postfix, from userid 10019) id EDC4B1240175; Fri, 7 Aug 2020 21:51:05 +0000 (UTC) From: Segher Boessenkool To: gcc-patches@gcc.gnu.org Subject: [PATCH] bb-reorder: Remove a misfiring micro-optimization (PR96475) Date: Fri, 7 Aug 2020 21:51:04 +0000 Message-Id: X-Mailer: git-send-email 1.8.3.1 In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Segher Boessenkool Errors-To: gcc-patches-bounces@gcc.gnu.org Sender: "Gcc-patches" When the compgotos pass copies the tail of blocks ending in an indirect jump, there is a micro-optimization to not copy the last one, since the original block will then just be deleted. This does not work properly if cleanup_cfg does not merge all pairs of blocks we expect it to. v2: This also deletes the other use of single_pred_p, which has the same problem in principle, I just never have triggered it so far. Tested on powerpc64-linux {-m32,-m64} like before. Is this okay for trunk? Segher 2020-08-07 Segher Boessenkool PR rtl-optimization/96475 * bb-reorder.c (maybe_duplicate_computed_goto): Remove single_pred_p micro-optimization. --- gcc/bb-reorder.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/gcc/bb-reorder.c b/gcc/bb-reorder.c index c635010..76e56b5 100644 --- a/gcc/bb-reorder.c +++ b/gcc/bb-reorder.c @@ -2680,9 +2680,6 @@ make_pass_reorder_blocks (gcc::context *ctxt) static bool maybe_duplicate_computed_goto (basic_block bb, int max_size) { - if (single_pred_p (bb)) - return false; - /* Make sure that the block is small enough. */ rtx_insn *insn; FOR_BB_INSNS (bb, insn) @@ -2700,10 +2697,9 @@ maybe_duplicate_computed_goto (basic_block bb, int max_size) { basic_block pred = e->src; - /* Do not duplicate BB into PRED if that is the last predecessor, or if - we cannot merge a copy of BB with PRED. */ - if (single_pred_p (bb) - || !single_succ_p (pred) + /* Do not duplicate BB into PRED if we cannot merge a copy of BB + with PRED. */ + if (!single_succ_p (pred) || e->flags & EDGE_COMPLEX || pred->index < NUM_FIXED_BLOCKS || (JUMP_P (BB_END (pred)) && !simplejump_p (BB_END (pred)))