This "fixes" PR50082 by passing comparison operands stripped off useless conversions to the canonicalization routine. This makes sure to fold the testcase early from a point where emitting a overflow warning is properly constrained.
Bootstrapped and tested on x86_64-unknown-linux-gnu, applied to trunk. Richard. 2011-08-15 Richard Guenther <rguent...@suse.de> PR middle-end/50082 * fold-const.c (maybe_canonicalize_comparison_1): Properly convert the modified operand to the other operand type. (fold_comparison): Call maybe_canonicalize_comparison_1 with useless conversions stripped from comparison operands. Index: gcc/fold-const.c =================================================================== --- gcc/fold-const.c (revision 177757) +++ gcc/fold-const.c (working copy) @@ -8446,6 +8446,7 @@ maybe_canonicalize_comparison_1 (locatio cst0, build_int_cst (TREE_TYPE (cst0), 1)); if (code0 != INTEGER_CST) t = fold_build2_loc (loc, code0, TREE_TYPE (arg0), TREE_OPERAND (arg0, 0), t); + t = fold_convert (TREE_TYPE (arg1), t); /* If swapping might yield to a more canonical form, do so. */ if (swap) @@ -8935,7 +8936,7 @@ fold_comparison (location_t loc, enum tr return fold_build2_loc (loc, cmp_code, type, variable1, const2); } - tem = maybe_canonicalize_comparison (loc, code, type, op0, op1); + tem = maybe_canonicalize_comparison (loc, code, type, arg0, arg1); if (tem) return tem;