From 69ca5f3a988266da8905aef9cf22aa02807e0471 Mon Sep 17 00:00:00 2001 From: Segher Boessenkool Date: Fri, 7 Aug 2020 01:31:38 +0000 Subject: [PATCH] bb-reorder: Remove a misfiring micro-optimization (PR96475) 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. It also does not work if that last block can be merged into multiple predecessors. 2020-09-09 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 c635010c69f..76e56b55a62 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))) -- 2.30.2