https://gcc.gnu.org/bugzilla/show_bug.cgi?id=93402
--- Comment #5 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:32667e04c7153d97d09d81c1af073d400f0c719a commit r10-6186-g32667e04c7153d97d09d81c1af073d400f0c719a Author: Jakub Jelinek <ja...@redhat.com> Date: Thu Jan 23 20:08:22 2020 +0100 postreload: Fix up postreload combine [PR93402] The following testcase is miscompiled, because the postreload pass changes: -(insn 14 13 23 2 (parallel [ - (set (reg:DI 1 dx [94]) - (plus:DI (reg:DI 1 dx [95]) - (reg:DI 5 di [92]))) - (clobber (reg:CC 17 flags)) - ]) "pr93402.c":8:30 186 {*adddi_1} - (expr_list:REG_EQUAL (plus:DI (reg:DI 5 di [92]) - (const_int 111111111111 [0x19debd01c7])) - (nil))) -(insn 23 14 25 2 (set (reg:SI 0 ax) +(insn 23 13 25 2 (set (reg:SI 0 ax) (const_int 0 [0])) "pr93402.c":10:1 67 {*movsi_internal} (nil)) (insn 25 23 26 2 (use (reg:SI 0 ax)) "pr93402.c":10:1 -1 (nil)) -(insn 26 25 35 2 (use (reg:DI 1 dx)) "pr93402.c":10:1 -1 +(insn 26 25 35 2 (use (plus:DI (reg:DI 1 dx [95]) + (reg:DI 5 di [92]))) "pr93402.c":10:1 -1 (nil)) A USE insn is not a normal insn and verify_changes called from apply_change_group is happy about any changes into it. The following patch avoids this optimization if we were to change the USE operand (this routine only changes a reg into (plus reg reg2)). 2020-01-23 Jakub Jelinek <ja...@redhat.com> PR rtl-optimization/93402 * postreload.c (reload_combine_recognize_pattern): Don't try to adjust USE insns. * gcc.c-torture/execute/pr93402.c: New test.
