diff options
| author | Richard Biener <rguenther@suse.de> | 2017-04-24 07:48:47 +0000 |
|---|---|---|
| committer | Richard Biener <rguenth@gcc.gnu.org> | 2017-04-24 07:48:47 +0000 |
| commit | 4c7c437cb1c851c54b991cb0d6da3c7c53900e3c (patch) | |
| tree | 7d7d028c48ecd3806a7a45193681e3027ad08786 /gcc/tree-ssa-sink.c | |
| parent | d21a8e3bc6325a94da178050181a4bcb7e017dfa (diff) | |
re PR tree-optimization/79725 (Sinking opportunity missed if blocked by dead stmt)
2017-04-24 Richard Biener <rguenther@suse.de>
PR tree-optimization/79725
* tree-ssa-sink.c (statement_sink_location): Return whether
failure reason was zero uses. Move that check later.
(sink_code_in_bb): Deal with zero uses by removing the stmt
if possible.
* gcc.dg/tree-ssa/ssa-sink-15.c: New testcase.
From-SVN: r247091
Diffstat (limited to 'gcc/tree-ssa-sink.c')
| -rw-r--r-- | gcc/tree-ssa-sink.c | 31 |
1 files changed, 23 insertions, 8 deletions
diff --git a/gcc/tree-ssa-sink.c b/gcc/tree-ssa-sink.c index 7a9fcde4f94..bb8d2ca9732 100644 --- a/gcc/tree-ssa-sink.c +++ b/gcc/tree-ssa-sink.c @@ -244,7 +244,7 @@ select_best_block (basic_block early_bb, static bool statement_sink_location (gimple *stmt, basic_block frombb, - gimple_stmt_iterator *togsi) + gimple_stmt_iterator *togsi, bool *zero_uses_p) { gimple *use; use_operand_p one_use = NULL_USE_OPERAND_P; @@ -254,6 +254,8 @@ statement_sink_location (gimple *stmt, basic_block frombb, ssa_op_iter iter; imm_use_iterator imm_iter; + *zero_uses_p = false; + /* We only can sink assignments. */ if (!is_gimple_assign (stmt)) return false; @@ -263,10 +265,6 @@ statement_sink_location (gimple *stmt, basic_block frombb, if (def_p == NULL_DEF_OPERAND_P) return false; - /* Return if there are no immediate uses of this stmt. */ - if (has_zero_uses (DEF_FROM_PTR (def_p))) - return false; - /* There are a few classes of things we can't or don't move, some because we don't have code to handle it, some because it's not profitable and some because it's not legal. @@ -292,11 +290,17 @@ statement_sink_location (gimple *stmt, basic_block frombb, */ if (stmt_ends_bb_p (stmt) || gimple_has_side_effects (stmt) - || gimple_has_volatile_ops (stmt) || (cfun->has_local_explicit_reg_vars && TYPE_MODE (TREE_TYPE (gimple_assign_lhs (stmt))) == BLKmode)) return false; + /* Return if there are no immediate uses of this stmt. */ + if (has_zero_uses (DEF_FROM_PTR (def_p))) + { + *zero_uses_p = true; + return false; + } + if (SSA_NAME_OCCURS_IN_ABNORMAL_PHI (DEF_FROM_PTR (def_p))) return false; @@ -483,12 +487,23 @@ sink_code_in_bb (basic_block bb) { gimple *stmt = gsi_stmt (gsi); gimple_stmt_iterator togsi; + bool zero_uses_p; - if (!statement_sink_location (stmt, bb, &togsi)) + if (!statement_sink_location (stmt, bb, &togsi, &zero_uses_p)) { + gimple_stmt_iterator saved = gsi; if (!gsi_end_p (gsi)) gsi_prev (&gsi); - last = false; + /* If we face a dead stmt remove it as it possibly blocks + sinking of uses. */ + if (zero_uses_p + && ! gimple_vdef (stmt)) + { + gsi_remove (&saved, true); + release_defs (stmt); + } + else + last = false; continue; } if (dump_file) |