https://gcc.gnu.org/bugzilla/show_bug.cgi?id=124358
--- Comment #10 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Jakub Jelinek <[email protected]>: https://gcc.gnu.org/g:acf7028b79b72176f8ab2f6ebc4dbb9b5fb11a48 commit r16-7923-gacf7028b79b72176f8ab2f6ebc4dbb9b5fb11a48 Author: Jakub Jelinek <[email protected]> Date: Fri Mar 6 08:14:09 2026 +0100 match.pd: Move cast into p+ operand for (ptr) (x p+ y) p+ z -> (ptr) (x p+ (y + z)) [PR124358] The following testcase is miscompiled since my r12-6382 change, because it doesn't play well with the gimple_fold_indirect_ref function which uses STRIP_NOPS and then has /* *(foo *)fooarrptr => (*fooarrptr)[0] */ if (TREE_CODE (TREE_TYPE (subtype)) == ARRAY_TYPE && TREE_CODE (TYPE_SIZE (TREE_TYPE (TREE_TYPE (subtype)))) == INTEGER_CST && useless_type_conversion_p (type, TREE_TYPE (TREE_TYPE (subtype)))) { tree type_domain; tree min_val = size_zero_node; tree osub = sub; sub = gimple_fold_indirect_ref (sub); if (! sub) sub = build1 (INDIRECT_REF, TREE_TYPE (subtype), osub); type_domain = TYPE_DOMAIN (TREE_TYPE (sub)); if (type_domain && TYPE_MIN_VALUE (type_domain)) min_val = TYPE_MIN_VALUE (type_domain); if (TREE_CODE (min_val) == INTEGER_CST) return build4 (ARRAY_REF, type, sub, min_val, NULL_TREE, NULL_TREE); } Without the GENERIC #if GENERIC (simplify (pointer_plus (convert:s (pointer_plus:s @0 @1)) @3) (convert:type (pointer_plus @0 (plus @1 @3)))) #endif we have INDIRECT_REF of POINTER_PLUS_EXPR with int * type of NOP_EXPR to that type of POINTER_PLUS_EXPR with pointer to int[4] ARRAY_TYPE, so gimple_fold_indirect_ref doesn't create the ARRAY_REF. But with it, it is simplified to NOP_EXPR to int * type from POINTER_PLUS_EXPR with pointer to int[4] ARRAY_TYPE, the NOP_EXPR is skipped over by STRIP_NOPS and the above code triggers. The following patch fixes it by swapping the order, do NOP_EXPR inside of POINTER_PLUS_EXPR first argument instead of NOP_EXPR with POINTER_PLUS_EXPR. 2026-03-06 Jakub Jelinek <[email protected]> PR tree-optimization/124358 * match.pd ((ptr) (x p+ y) p+ z -> (ptr) (x p+ (y + z))): Simplify into (ptr) x p+ (y + z) instead. * gcc.c-torture/execute/pr124358.c: New test.
