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| author | Segher Boessenkool <segher@kernel.crashing.org> | 2020-08-07 01:31:38 +0000 |
|---|---|---|
| committer | Segher Boessenkool <segher@kernel.crashing.org> | 2020-09-09 16:55:22 +0000 |
| commit | 69ca5f3a988266da8905aef9cf22aa02807e0471 (patch) | |
| tree | 661a3de4c286667c65fa793edf8a63e48399540b | |
| parent | ad2a37157d3476dffb3baf93ca5001c9f6c44bda (diff) | |
| download | gcc-69ca5f3a988266da8905aef9cf22aa02807e0471.zip gcc-69ca5f3a988266da8905aef9cf22aa02807e0471.tar.gz gcc-69ca5f3a988266da8905aef9cf22aa02807e0471.tar.bz2 | |
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 <segher@kernel.crashing.org>
PR rtl-optimization/96475
* bb-reorder.c (maybe_duplicate_computed_goto): Remove single_pred_p
micro-optimization.
| -rw-r--r-- | gcc/bb-reorder.c | 10 |
1 files 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))) |