[Bug tree-optimization/105337] [12 Regression] wrong code at -Os and above on x86_64-linux-gnu

[mpolacek at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=105337

Marek Polacek <mpolacek at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P1
             Status|UNCONFIRMED                 |NEW
   Target Milestone|---                         |12.0
                 CC|                            |aoliva at gcc dot gnu.org,
                   |                            |mpolacek at gcc dot gnu.org
     Ever confirmed|0                           |1
           Keywords|                            |wrong-code
   Last reconfirmed|                            |2022-04-21
            Summary|wrong code at -Os and above |[12 Regression] wrong code
                   |on x86_64-linux-gnu         |at -Os and above on
                   |                            |x86_64-linux-gnu

--- Comment #2 from Marek Polacek <mpolacek at gcc dot gnu.org> ---
Confirmed.  Started with r12-397-gda9e6e63d1ae22, in particular this hunk:

--- a/gcc/passes.def
+++ b/gcc/passes.def
@@ -336,8 +336,9 @@ along with GCC; see the file COPYING3.  If not see
       NEXT_PASS (pass_thread_jumps);
       NEXT_PASS (pass_vrp, false /* warn_array_bounds_p */);
       /* Threading can leave many const/copy propagations in the IL.
-    Clean them up.  */
-      NEXT_PASS (pass_copy_prop);
+    Clean them up.  Instead of just copy_prop, we use ccp to
+    compute alignment and nonzero bits.  */
+      NEXT_PASS (pass_ccp, true /* nonzero_p */);
       NEXT_PASS (pass_warn_restrict);
       NEXT_PASS (pass_dse);
       NEXT_PASS (pass_cd_dce, true /* update_address_taken_p */);