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From: Alexandre Oliva <aoliva@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc(refs/users/aoliva/heads/testme)] [PR105665] ivopts: check defs of names in base for undefs Date: Sat, 28 May 2022 00:09:39 +0000 (GMT) [thread overview] Message-ID: <20220528000939.9AA98383A329@sourceware.org> (raw) https://gcc.gnu.org/g:781277269a6c76123d8ca5b38dbe9ab63a0fd699 commit 781277269a6c76123d8ca5b38dbe9ab63a0fd699 Author: Alexandre Oliva <oliva@adacore.com> Date: Thu May 26 09:38:31 2022 -0300 [PR105665] ivopts: check defs of names in base for undefs The patch for PR 100810 tested for undefined SSA_NAMEs appearing directly in the base expression of the potential IV candidate, but that's not enough. The testcase for PR105665 shows an undefined SSA_NAME has the same ill effect if it's referenced as an PHI_NODE arg in the referenced SSA_NAME. The variant of that test shows it can be further removed from the referenced SSA_NAME. Turning the test for undefined SSA_NAMES into a recursive search, skipping cycles and other duplicates, avoids the problem. for gcc/ChangeLog PR tree-optimization/105665 PR tree-optimization/100810 * tree-ssa-loop-ivopts.cc (find_ssa_undef): Take pointer set as argument, use it to avoid duplicates. Recurse on SSA_NAMEs mentioned in each def. (add_candidate_1): Start the search with an empty pointer set. for gcc/testsuite/ChangeLog PR tree-optimization/105665 PR tree-optimization/100810 * gcc.dg/torture/pr105665.c: New. Diff: --- gcc/testsuite/gcc.dg/torture/pr105665.c | 20 +++++++++++++ gcc/tree-ssa-loop-ivopts.cc | 51 +++++++++++++++++++++++++++++---- 2 files changed, 65 insertions(+), 6 deletions(-) diff --git a/gcc/testsuite/gcc.dg/torture/pr105665.c b/gcc/testsuite/gcc.dg/torture/pr105665.c new file mode 100644 index 00000000000..34cfc658434 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr105665.c @@ -0,0 +1,20 @@ +/* { dg-do run } */ + +int a, b, c[1], d[2], *e = c; +int main() { + int f = 0; + for (; b < 2; b++) { + int g; + if (f) + g++, b = 40; + a = d[b * b]; + for (f = 0; f < 3; f++) { + if (e) + break; + g--; + if (a) + a = g; + } + } + return 0; +} diff --git a/gcc/tree-ssa-loop-ivopts.cc b/gcc/tree-ssa-loop-ivopts.cc index 81b536f9304..adf9010ad67 100644 --- a/gcc/tree-ssa-loop-ivopts.cc +++ b/gcc/tree-ssa-loop-ivopts.cc @@ -3071,14 +3071,52 @@ get_loop_invariant_expr (struct ivopts_data *data, tree inv_expr) return *slot; } -/* Find the first undefined SSA name in *TP. */ +/* Find the first undefined SSA name in *TP. Use PSET_, a + hash_set<tree>*, to avoid cycles and to skip other duplicates. */ static tree -find_ssa_undef (tree *tp, int *walk_subtrees, void *) +find_ssa_undef (tree *tp, int *walk_subtrees, void *pset_) { - if (TREE_CODE (*tp) == SSA_NAME - && ssa_undefined_value_p (*tp, false)) - return *tp; + auto pset = static_cast<hash_set<tree> *> (pset_); + + if (TREE_CODE (*tp) == SSA_NAME) + { + if (ssa_defined_default_def_p (*tp)) + return NULL; + + if (ssa_undefined_value_p (*tp, false)) + return *tp; + + /* If we've already visited this SSA_NAME and got to it again, + we know we didn't find it to be undefined, otherwise we'd + have stopped the walk then. */ + if (pset && pset->add (*tp)) + return NULL; + + gimple *def_stmt = SSA_NAME_DEF_STMT (*tp); + /* ssa_undefined_value_p must have caught nop defs above. */ + gcc_checking_assert (!gimple_nop_p (def_stmt)); + + /* No need to follow these: uses' undefinedness does not + propagate to defs. ??? Even inlined calls? */ + if (is_gimple_call (def_stmt) + || is_a <gasm *> (def_stmt)) + return NULL; + + ssa_op_iter iter; + use_operand_p use_p; + + FOR_EACH_PHI_OR_STMT_USE (use_p, def_stmt, iter, SSA_OP_USE) + { + tree use = USE_FROM_PTR (use_p); + + int wsub = 1; + tree result = find_ssa_undef (&use, &wsub, pset); + if (result) + return result; + } + } + if (!EXPR_P (*tp)) *walk_subtrees = 0; return NULL; @@ -3114,7 +3152,8 @@ add_candidate_1 (struct ivopts_data *data, tree base, tree step, bool important, /* If BASE contains undefined SSA names make sure we only record the original IV. */ bool involves_undefs = false; - if (walk_tree (&base, find_ssa_undef, NULL, NULL)) + hash_set<tree> pset; + if (walk_tree (&base, find_ssa_undef, &pset, NULL)) { if (pos != IP_ORIGINAL) return NULL;
next reply other threads:[~2022-05-28 0:09 UTC|newest] Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-05-28 0:09 Alexandre Oliva [this message] -- strict thread matches above, loose matches on Subject: below -- 2022-06-02 11:58 Alexandre Oliva 2022-06-02 1:27 Alexandre Oliva 2022-05-28 4:45 Alexandre Oliva 2022-05-28 0:11 Alexandre Oliva 2022-05-26 15:46 Alexandre Oliva 2022-05-26 15:46 Alexandre Oliva 2022-05-26 14:29 Alexandre Oliva 2022-05-26 13:11 Alexandre Oliva 2022-05-26 12:49 Alexandre Oliva 2022-05-26 12:49 Alexandre Oliva
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