https://gcc.gnu.org/bugzilla/show_bug.cgi?id=91029
--- Comment #12 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <ja...@gcc.gnu.org>: https://gcc.gnu.org/g:d3f293348768667c07770e433ff00af51fee73a2 commit r11-5186-gd3f293348768667c07770e433ff00af51fee73a2 Author: Jakub Jelinek <ja...@redhat.com> Date: Fri Nov 20 00:02:21 2020 +0100 ranger: Improve a % b operand ranges [PR91029] As mentioned in the PR, the previous PR91029 patch was testing op2 >= 0 which is unnecessary, even negative op2 values will work the same, furthermore, from if a % b > 0 we can deduce a > 0 rather than just a >= 0 (0 % b would be 0), and it actually valid even for other constants than 0, a % b > 5 means a > 5 (a % b has the same sign as a and a in [0, 5] would result in a % b in [0, 5]. Also, we can deduce a range for the other operand, if we know a % b >= 20, then b must be (in absolute value for signed modulo) > 20, for a % [0, 20] the result would be [0, 19]. 2020-11-19 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/91029 * range-op.cc (operator_trunc_mod::op1_range): Don't require signed types, nor require that op2 >= 0. Implement (a % b) >= x && x > 0 implies a >= x and (a % b) <= x && x < 0 implies a <= x. (operator_trunc_mod::op2_range): New method. * gcc.dg/tree-ssa/pr91029-1.c: New test. * gcc.dg/tree-ssa/pr91029-2.c: New test.
