[Bug tree-optimization/70729] Loop marked with omp simd pragma is not vectorized

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=70729

--- Comment #8 from Richard Biener <rguenth at gcc dot gnu.org> ---
Index: gcc/passes.def
===================================================================
--- gcc/passes.def      (revision 235237)
+++ gcc/passes.def      (working copy)
@@ -244,6 +244,7 @@ along with GCC; see the file COPYING3.
       NEXT_PASS (pass_cse_sincos);
       NEXT_PASS (pass_optimize_bswap);
       NEXT_PASS (pass_laddress);
+      NEXT_PASS (pass_lim);
       NEXT_PASS (pass_split_crit_edges);
       NEXT_PASS (pass_pre);
       NEXT_PASS (pass_sink_code);
@@ -257,10 +258,8 @@ along with GCC; see the file COPYING3.
       NEXT_PASS (pass_fix_loops);
       NEXT_PASS (pass_tree_loop);
       PUSH_INSERT_PASSES_WITHIN (pass_tree_loop)
-         NEXT_PASS (pass_tree_loop_init);
-         NEXT_PASS (pass_lim);
-         NEXT_PASS (pass_copy_prop);
          NEXT_PASS (pass_dce);
+         NEXT_PASS (pass_tree_loop_init);
          NEXT_PASS (pass_tree_unswitch);
          NEXT_PASS (pass_scev_cprop);
          NEXT_PASS (pass_record_bounds);

will then vectorize the loop successfully.  I'm quite sympathetic to moving
LIM before PRE (removing copy-prop might pessimize -O1 where PRE doesn't run,
but -O1 should use a different pipeline, maybe based on the -Og one...).
It also moves LIM out of -ftree-loop-optimize (the oacc kernels group also
runs LIM independent on -ftree-loop-optimize).