https://gcc.gnu.org/bugzilla/show_bug.cgi?id=121962
--- Comment #14 from GCC Commits <cvs-commit at gcc dot gnu.org> --- The trunk branch has been updated by Andrew Pinski <pins...@gcc.gnu.org>: https://gcc.gnu.org/g:a7a9f0de4fe01ee96350892066afbe5aca4bc0a6 commit r16-3936-ga7a9f0de4fe01ee96350892066afbe5aca4bc0a6 Author: Andrew Pinski <andrew.pin...@oss.qualcomm.com> Date: Tue Sep 16 10:55:03 2025 -0700 forwprop: Fix up "nop" copies after recent changes [PR121962] After r16-3887-g597b50abb0d2fc, the check to see if the copy is a nop copy becomes inefficient. The code going into an infinite loop as the copy keeps on being propagated over and over again. That is if we have: ``` struct s1 *b = &a.t; a.t = *b; p = *b; ``` This goes into an infinite loop propagating over and over again the `MEM[&a]`. To solve this a new function is needed for the comparison that is similar to new_src_based_on_copy. PR tree-optimization/121962 gcc/ChangeLog: * tree-ssa-forwprop.cc (same_for_assignment): New function. (optimize_agr_copyprop_1): Use same_for_assignment to check for nop copies. (optimize_agr_copyprop): Likewise. gcc/testsuite/ChangeLog: * gcc.dg/torture/pr121962-1.c: New test. Signed-off-by: Andrew Pinski <andrew.pin...@oss.qualcomm.com>
