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| author | Richard Biener <rguenther@suse.de> | 2021-04-13 12:05:53 +0200 |
|---|---|---|
| committer | Richard Biener <rguenther@suse.de> | 2021-04-13 14:30:57 +0200 |
| commit | f9810422f6768b914aabfcbffe64f535bdd18452 (patch) | |
| tree | 96b2f7b6ee006f585366f93b6726acf97a5fe776 /gcc/tree-ssa-sccvn.c | |
| parent | 0851ac6df0596df1e3b640e58094cf94ebb790b8 (diff) | |
| download | gcc-f9810422f6768b914aabfcbffe64f535bdd18452.zip gcc-f9810422f6768b914aabfcbffe64f535bdd18452.tar.gz gcc-f9810422f6768b914aabfcbffe64f535bdd18452.tar.bz2 | |
tree-optimization/100053 - fix predication in VN
This avoids doing optimistic dominance queries involving
non-executable backedges when validating recorded predicated values
in VN because we have no way to force re-evaluating validity when
optimistically not executable edges become executable later.
2021-04-13 Richard Biener <rguenther@suse.de>
PR tree-optimization/100053
* tree-ssa-sccvn.c (vn_nary_op_get_predicated_value): Do
not use optimistic dominance queries for backedges to validate
predicated values.
(dominated_by_p_w_unex): Add parameter to ignore executable
state on backedges.
(rpo_elim::eliminate_avail): Adjust.
* gcc.dg/torture/pr100053.c: New testcase.
* gcc.dg/tree-ssa/ssa-fre-93.c: Likewise.
Diffstat (limited to 'gcc/tree-ssa-sccvn.c')
| -rw-r--r-- | gcc/tree-ssa-sccvn.c | 21 |
1 files changed, 13 insertions, 8 deletions
diff --git a/gcc/tree-ssa-sccvn.c b/gcc/tree-ssa-sccvn.c index 16e75b5..ca0974d 100644 --- a/gcc/tree-ssa-sccvn.c +++ b/gcc/tree-ssa-sccvn.c @@ -4171,7 +4171,7 @@ vn_nary_op_insert_pieces_predicated (unsigned int length, enum tree_code code, } static bool -dominated_by_p_w_unex (basic_block bb1, basic_block bb2); +dominated_by_p_w_unex (basic_block bb1, basic_block bb2, bool); static tree vn_nary_op_get_predicated_value (vn_nary_op_t vno, basic_block bb) @@ -4180,9 +4180,12 @@ vn_nary_op_get_predicated_value (vn_nary_op_t vno, basic_block bb) return vno->u.result; for (vn_pval *val = vno->u.values; val; val = val->next) for (unsigned i = 0; i < val->n; ++i) - if (dominated_by_p_w_unex (bb, - BASIC_BLOCK_FOR_FN - (cfun, val->valid_dominated_by_p[i]))) + /* Do not handle backedge executability optimistically since + when figuring out whether to iterate we do not consider + changed predication. */ + if (dominated_by_p_w_unex + (bb, BASIC_BLOCK_FOR_FN (cfun, val->valid_dominated_by_p[i]), + false)) return val->result; return NULL_TREE; } @@ -4482,10 +4485,11 @@ vn_phi_insert (gimple *phi, tree result, bool backedges_varying_p) /* Return true if BB1 is dominated by BB2 taking into account edges - that are not executable. */ + that are not executable. When ALLOW_BACK is false consider not + executable backedges as executable. */ static bool -dominated_by_p_w_unex (basic_block bb1, basic_block bb2) +dominated_by_p_w_unex (basic_block bb1, basic_block bb2, bool allow_back) { edge_iterator ei; edge e; @@ -4502,7 +4506,8 @@ dominated_by_p_w_unex (basic_block bb1, basic_block bb2) { edge prede = NULL; FOR_EACH_EDGE (e, ei, bb1->preds) - if (e->flags & EDGE_EXECUTABLE) + if ((e->flags & EDGE_EXECUTABLE) + || (!allow_back && (e->flags & EDGE_DFS_BACK))) { if (prede) { @@ -6901,7 +6906,7 @@ rpo_elim::eliminate_avail (basic_block bb, tree op) may also be able to "pre-compute" (bits of) the next immediate (non-)dominator during the RPO walk when marking edges as executable. */ - if (dominated_by_p_w_unex (bb, abb)) + if (dominated_by_p_w_unex (bb, abb, true)) { tree leader = ssa_name (av->leader); /* Prevent eliminations that break loop-closed SSA. */ |