https://gcc.gnu.org/bugzilla/show_bug.cgi?id=109505
--- Comment #27 from CVS Commits <cvs-commit at gcc dot gnu.org> --- The releases/gcc-11 branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:ca4a4cc0060cb8ae1a326d6dbfcd9459452e1574 commit r11-10841-gca4a4cc0060cb8ae1a326d6dbfcd9459452e1574 Author: Jakub Jelinek <ja...@redhat.com> Date: Sun May 21 13:36:56 2023 +0200 match.pd: Ensure (op CONSTANT_CLASS_P CONSTANT_CLASS_P) is simplified [PR109505] On the following testcase we hang, because POLY_INT_CST is CONSTANT_CLASS_P, but BIT_AND_EXPR with it and INTEGER_CST doesn't simplify and the (x | CST1) & CST2 -> (x & CST2) | (CST1 & CST2) simplification actually relies on the (CST1 & CST2) simplification, otherwise it is a deoptimization, trading 2 ops for 3 and furthermore running into /* Given a bit-wise operation CODE applied to ARG0 and ARG1, see if both operands are another bit-wise operation with a common input. If so, distribute the bit operations to save an operation and possibly two if constants are involved. For example, convert (A | B) & (A | C) into A | (B & C) Further simplification will occur if B and C are constants. */ simplification which simplifies that (x & CST2) | (CST1 & CST2) back to CST2 & (x | CST1). I went through all other places I could find where we have a simplification with 2 CONSTANT_CLASS_P operands and perform some operation on those two, while the other spots aren't that severe (just trade 2 operations for another 2 if the two constants don't simplify, rather than as in the above case trading 2 ops for 3), I still think all those spots really intend to optimize only if the 2 constants simplify. So, the following patch adds to those a ! modifier to ensure that, even at GENERIC that modifier means !EXPR_P which is exactly what we want IMHO. 2023-05-21 Jakub Jelinek <ja...@redhat.com> PR tree-optimization/109505 * match.pd ((x | CST1) & CST2 -> (x & CST2) | (CST1 & CST2), Combine successive equal operations with constants, (A +- CST1) +- CST2 -> A + CST3, (CST1 - A) +- CST2 -> CST3 - A, CST1 - (CST2 - A) -> CST3 + A): Use ! on ops with 2 CONSTANT_CLASS_P operands. * gcc.target/aarch64/sve/pr109505.c: New test. (cherry picked from commit f211757f6fa9515e3fd1a4f66f1a8b48e500c9de)
