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From: Jakub Jelinek <jakub@gcc.gnu.org> To: gcc-cvs@gcc.gnu.org Subject: [gcc r13-6074] reassoc: Fix up (ab) handling in eliminate_redundant_comparison [PR108783] Date: Thu, 16 Feb 2023 09:42:00 +0000 (GMT) [thread overview] Message-ID: <20230216094201.54E7B3858409@sourceware.org> (raw) https://gcc.gnu.org/g:55db240d28d29aac90a2d2af3768283ba6288752 commit r13-6074-g55db240d28d29aac90a2d2af3768283ba6288752 Author: Jakub Jelinek <jakub@redhat.com> Date: Thu Feb 16 10:41:18 2023 +0100 reassoc: Fix up (ab) handling in eliminate_redundant_comparison [PR108783] The following testcase ICEs because eliminate_redundant_comparison sees redundant comparisons in &&/|| where the comparison has (ab) SSA_NAME, maybe_fold_{and,or}_comparisons optimizes them into a single comparison and build_and_add_sum emits a new comparison close to the definition operands, which in this case is before a returns_twice call (which is invalid). Generally reassoc just punts on (ab) SSA_NAMEs, declares them non-reassociable etc., so the second half of this patch does that. Though we can do better in this case; the function has special code when maybe_fold_{and,or}_comparisons returns INTEGER_CST (false/true) or when what it returns is the same as curr->op (the first of the comparisons we are considering) - in that case we just remove the second one and keep the first one. The reason it doesn't match is that curr->op is a SSA_NAME whose SSA_NAME_DEF_STMT is checked to be a comparison, in this case _42 = a_1(ab) != 0 and the other comparison is also like that. maybe_fold_{and,or}_comparisons looks through the definitions though and so returns a_1(ab) != 0 as tree. So the first part of the patch checks whether that returned comparison isn't the same as the curr->op comparison and if yes, it just overrides t back to curr->op so that its SSA_NAME is reused. In that case we can handle even (ab) in {,new}op{1,2} because we don't create a new comparison of that, just keep using the existing one. And t can't be (ab) because otherwise it wouldn't be considered a reassociable operand. The (ab) checks are needed say when we have a_1(ab) == 42 || a_1(ab) > 42 kind of comparisons where maybe_fold_{and,or}_comparisons returns a new comparison not existing in the IL yet. 2023-02-16 Jakub Jelinek <jakub@redhat.com> PR tree-optimization/108783 * tree-ssa-reassoc.cc (eliminate_redundant_comparison): If lcode is equal to TREE_CODE (t), op1 to newop1 and op2 to newop2, set t to curr->op. Otherwise, punt if either newop1 or newop2 are SSA_NAME_OCCURS_IN_ABNORMAL_PHI SSA_NAMEs. * gcc.c-torture/compile/pr108783.c: New test. Diff: --- gcc/testsuite/gcc.c-torture/compile/pr108783.c | 42 ++++++++++++++++++++++++++ gcc/tree-ssa-reassoc.cc | 9 ++++++ 2 files changed, 51 insertions(+) diff --git a/gcc/testsuite/gcc.c-torture/compile/pr108783.c b/gcc/testsuite/gcc.c-torture/compile/pr108783.c new file mode 100644 index 00000000000..eae87db36d7 --- /dev/null +++ b/gcc/testsuite/gcc.c-torture/compile/pr108783.c @@ -0,0 +1,42 @@ +/* PR tree-optimization/108783 */ + +__attribute__((returns_twice)) int baz (int, int); + +int +bar (int x) +{ + return x; +} + +int +foo (int x, int y) +{ + int a; + + a = bar (x); + baz (x, y); + + return y && a && a; +} + +int +qux (int x, int y) +{ + int a; + + a = bar (x); + baz (x, y); + + return y && a != 42 && a >= 42; +} + +int +corge (int x, int y) +{ + int a; + + a = bar (x); + baz (x, y); + + return y || a == 42 || a > 42; +} diff --git a/gcc/tree-ssa-reassoc.cc b/gcc/tree-ssa-reassoc.cc index 5522a3ada8e..f163612f140 100644 --- a/gcc/tree-ssa-reassoc.cc +++ b/gcc/tree-ssa-reassoc.cc @@ -2272,6 +2272,15 @@ eliminate_redundant_comparison (enum tree_code opcode, STRIP_USELESS_TYPE_CONVERSION (newop2); if (!is_gimple_val (newop1) || !is_gimple_val (newop2)) continue; + if (lcode == TREE_CODE (t) + && operand_equal_p (op1, newop1, 0) + && operand_equal_p (op2, newop2, 0)) + t = curr->op; + else if ((TREE_CODE (newop1) == SSA_NAME + && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (newop1)) + || (TREE_CODE (newop2) == SSA_NAME + && SSA_NAME_OCCURS_IN_ABNORMAL_PHI (newop2))) + continue; } if (dump_file && (dump_flags & TDF_DETAILS))
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