https://gcc.gnu.org/g:01b59a948f8240f81b61c42de13362c2a172f72e
commit r14-12291-g01b59a948f8240f81b61c42de13362c2a172f72e Author: Andrew Pinski <[email protected]> Date: Thu Sep 19 13:50:14 2024 -0700 match: Fix `a != 0 ? a * b : 0` patterns for things that trap [PR116772] For generic, `a != 0 ? a * b : 0` would match where `b` would be an expression which trap (in the case of the testcase, it was an integer division but it could be any). This adds a new helper function, expr_no_side_effects_p which tests if there is no side effects and the expression is not trapping which might be used in other locations. Changes since v1: * v2: Add move check to helper function instead of inlining it. PR middle-end/116772 gcc/ChangeLog: * generic-match-head.cc (expr_no_side_effects_p): New function * gimple-match-head.cc (expr_no_side_effects_p): New function gcc/testsuite/ChangeLog: * gcc.dg/torture/pr116772-1.c: New test. Signed-off-by: Andrew Pinski <[email protected]> (cherry picked from commit 6c5543d3d9c4bbcd19f0ae2b7ed7e523c978a9a8) Diff: --- gcc/generic-match-head.cc | 12 ++++++++++++ gcc/gimple-match-head.cc | 10 ++++++++++ gcc/testsuite/gcc.dg/torture/pr116772-1.c | 24 ++++++++++++++++++++++++ 3 files changed, 46 insertions(+) diff --git a/gcc/generic-match-head.cc b/gcc/generic-match-head.cc index 0d3f648fe8db..67ce95d3de5c 100644 --- a/gcc/generic-match-head.cc +++ b/gcc/generic-match-head.cc @@ -105,6 +105,18 @@ optimize_successive_divisions_p (tree, tree) return false; } +/* Returns true if the expression T has no side effects + including not trapping. */ +static inline bool +expr_no_side_effects_p (tree t) +{ + if (TREE_SIDE_EFFECTS (t)) + return false; + if (generic_expr_could_trap_p (t)) + return false; + return true; +} + /* Return true if EXPR1 and EXPR2 have the same value, but not necessarily same type. The types can differ through nop conversions. */ diff --git a/gcc/gimple-match-head.cc b/gcc/gimple-match-head.cc index 5f8a1a1ad8e3..697e69a5ba5d 100644 --- a/gcc/gimple-match-head.cc +++ b/gcc/gimple-match-head.cc @@ -135,6 +135,16 @@ optimize_vectors_before_lowering_p () return !cfun || (cfun->curr_properties & PROP_gimple_lvec) == 0; } +/* Returns true if the expression T has no side effects + including not trapping. */ +static inline bool +expr_no_side_effects_p (tree t) +{ + /* For gimple, there should only be gimple val's here. */ + gcc_assert (is_gimple_val (t)); + return true; +} + /* Return true if pow(cst, x) should be optimized into exp(log(cst) * x). As a workaround for SPEC CPU2017 628.pop2_s, don't do it if arg0 is an exact integer, arg1 = phi_res +/- cst1 and phi_res = PHI <cst2, ...> diff --git a/gcc/testsuite/gcc.dg/torture/pr116772-1.c b/gcc/testsuite/gcc.dg/torture/pr116772-1.c new file mode 100644 index 000000000000..eedd0398af16 --- /dev/null +++ b/gcc/testsuite/gcc.dg/torture/pr116772-1.c @@ -0,0 +1,24 @@ +/* { dg-do run } */ +/* PR middle-end/116772 */ +/* The division by `/b` should not + be made uncondtional. */ + +int mult0(int a,int b) __attribute__((noipa)); + +int mult0(int a,int b){ + return (b!=0 ? (a/b)*b : 0); +} + +int bit_and0(int a,int b) __attribute__((noipa)); + +int bit_and0(int a,int b){ + return (b!=0 ? (a/b)&b : 0); +} + +int main() { + if (mult0(3, 0) != 0) + __builtin_abort(); + if (bit_and0(3, 0) != 0) + __builtin_abort(); + return 0; +}
