https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114121
--- Comment #15 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The master branch has been updated by Richard Biener <rgue...@gcc.gnu.org>: https://gcc.gnu.org/g:c841144a94363ff26e40ab3f26b14702c32987a8 commit r14-9215-gc841144a94363ff26e40ab3f26b14702c32987a8 Author: Richard Biener <rguent...@suse.de> Date: Wed Feb 28 12:37:07 2024 +0100 tree-optimization/114121 - wrong VN with context sensitive range info When VN ends up exploiting range-info specifying the ao_ref offset and max_size we have to make sure to reflect this in the hashtable entry for the recorded expression. The PR113831 fix handled the case where we can encode this in the operands themselves but this bug shows the issue is more widespread. So instead of altering the operands the following instead records this extra info that's possibly used, only throwing it away when the value-numbering didn't come up with a non-VARYING value which is an important detail to preserve CSE as opposed to constant folding which is where all cases currently known popped up. With this the original PR113831 fix can be reverted. PR tree-optimization/114121 * tree-ssa-sccvn.h (vn_reference_s::offset, vn_reference_s::max_size): New fields. (vn_reference_insert_pieces): Adjust prototype. * tree-ssa-pre.cc (phi_translate_1): Preserve offset/max_size. * tree-ssa-sccvn.cc (vn_reference_eq): Compare offset and size, allow using "don't know" state. (vn_walk_cb_data::finish): Pass along offset/max_size. (vn_reference_lookup_or_insert_for_pieces): Take offset and max_size as argument and use it. (vn_reference_lookup_3): Properly adjust offset and max_size according to the adjusted ao_ref. (vn_reference_lookup_pieces): Initialize offset and max_size. (vn_reference_lookup): Likewise. (vn_reference_lookup_call): Likewise. (vn_reference_insert): Likewise. (visit_reference_op_call): Likewise. (vn_reference_insert_pieces): Take offset and max_size as argument and use it. * gcc.dg/torture/pr114121.c: New testcase.
