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| author | Richard Biener <rguenther@suse.de> | 2020-11-03 15:03:41 +0100 |
|---|---|---|
| committer | Richard Biener <rguenther@suse.de> | 2020-11-03 16:23:06 +0100 |
| commit | c5b49c3e092c0de5cd684b0acd244129dfaae324 (patch) | |
| tree | 26c53d09691a9fff15eff1e8e04159df25b925b1 /gcc/tree-ssa-pre.c | |
| parent | d0d8a1658054258baae87b445678c1c0c08d9455 (diff) | |
| download | gcc-c5b49c3e092c0de5cd684b0acd244129dfaae324.zip gcc-c5b49c3e092c0de5cd684b0acd244129dfaae324.tar.gz gcc-c5b49c3e092c0de5cd684b0acd244129dfaae324.tar.bz2 | |
tree-optimization/97623 - limit PRE hoist insertion
This limits insert iteration caused by PRE insertions generating
hoist insertion opportunities and vice versa. The patch limits
the hoist insertion iterations to three by default.
2020-11-03 Richard Biener <rguenther@suse.de>
PR tree-optimization/97623
* params.opt (-param=max-pre-hoist-insert-iterations): New.
* doc/invoke.texi (max-pre-hoist-insert-iterations): Document.
* tree-ssa-pre.c (insert): Do at most max-pre-hoist-insert-iterations
hoist insert iterations.
Diffstat (limited to 'gcc/tree-ssa-pre.c')
| -rw-r--r-- | gcc/tree-ssa-pre.c | 7 |
1 files changed, 5 insertions, 2 deletions
diff --git a/gcc/tree-ssa-pre.c b/gcc/tree-ssa-pre.c index 091ecb3..39c52c9 100644 --- a/gcc/tree-ssa-pre.c +++ b/gcc/tree-ssa-pre.c @@ -3647,8 +3647,11 @@ insert (void) changed = false; /* Insert expressions for hoisting. Do a backward walk here since - inserting into BLOCK exposes new opportunities in its predecessors. */ - if (flag_code_hoisting) + inserting into BLOCK exposes new opportunities in its predecessors. + Since PRE and hoist insertions can cause back-to-back iteration + limit that on the hoist side. */ + if (flag_code_hoisting + && num_iterations <= param_max_pre_hoist_insert_iterations) for (int idx = rpo_num - 1; idx >= 0; --idx) { basic_block block = BASIC_BLOCK_FOR_FN (cfun, rpo[idx]); |