https://gcc.gnu.org/bugzilla/show_bug.cgi?id=69467
Richard Biener <rguenth at gcc dot gnu.org> changed: What |Removed |Added ---------------------------------------------------------------------------- Status|UNCONFIRMED |ASSIGNED Last reconfirmed| |2016-01-25 Assignee|unassigned at gcc dot gnu.org |rguenth at gcc dot gnu.org Target Milestone|--- |6.0 Ever confirmed|0 |1 --- Comment #2 from Richard Biener <rguenth at gcc dot gnu.org> --- To restore the state before the move from fold to match.pd we'd need to mark any such pattern involving compares as the outermost expr (and thus match on GIMPLE_CONDs) with an explicit && single_use () check. Fix for this one: Index: gcc/match.pd =================================================================== --- gcc/match.pd (revision 232792) +++ gcc/match.pd (working copy) @@ -1821,12 +1821,13 @@ DEFINE_INT_AND_FLOAT_ROUND_FN (RINT) (for cmp (simple_comparison) scmp (swapped_simple_comparison) (simplify - (cmp (mult @0 INTEGER_CST@1) integer_zerop@2) + (cmp (mult@3 @0 INTEGER_CST@1) integer_zerop@2) /* Handle unfolded multiplication by zero. */ (if (integer_zerop (@1)) (cmp @1 @2) (if (ANY_INTEGRAL_TYPE_P (TREE_TYPE (@0)) - && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0))) + && TYPE_OVERFLOW_UNDEFINED (TREE_TYPE (@0)) + && single_use (@3)) /* If @1 is negative we swap the sense of the comparison. */ (if (tree_int_cst_sgn (@1) < 0) (scmp @0 @2)