tree-optimization/95045 - fix SM with exit exiting multiple loops

Since we apply SM to an edge which exits multiple loops we have
to make sure to commit insertions on it immediately since otherwise
store order is not preserved.

2020-05-12  Richard Biener  <rguenther@suse.de>

	PR tree-optimization/95045
	* dbgcnt.def (lim): Add debug-counter.
	* tree-ssa-loop-im.c: Include dbgcnt.h.
	(find_refs_for_sm): Use lim debug counter for store motion
	candidates.
	(do_store_motion): Rename form store_motion.  Commit edge
	insertions...
	(store_motion_loop): ... here.
	(tree_ssa_lim): Adjust.

1 files changed, 10 insertions, 5 deletions

diff --git a/gcc/tree-ssa-loop-im.c b/gcc/tree-ssa-loop-im.c
index bb78dfb..0d77aaa 100644
--- a/gcc/tree-ssa-loop-im.c
+++ b/gcc/tree-ssa-loop-im.c
@@ -47,6 +47,7 @@ along with GCC; see the file COPYING3.  If not see
 #include "alias.h"
 #include "builtins.h"
 #include "tree-dfa.h"
+#include "dbgcnt.h"
 
 /* TODO:  Support for predicated code motion.  I.e.
 
@@ -2862,7 +2863,7 @@ find_refs_for_sm (class loop *loop, bitmap sm_executed, bitmap refs_to_sm)
   EXECUTE_IF_AND_COMPL_IN_BITMAP (refs, sm_executed, 0, i, bi)
     {
       ref = memory_accesses.refs_list[i];
-      if (can_sm_ref_p (loop, ref))
+      if (can_sm_ref_p (loop, ref) && dbg_cnt (lim))
 	bitmap_set_bit (refs_to_sm, i);
     }
 }
@@ -2900,7 +2901,12 @@ store_motion_loop (class loop *loop, bitmap sm_executed)
     {
       find_refs_for_sm (loop, sm_executed, sm_in_loop);
       if (!bitmap_empty_p (sm_in_loop))
-	hoist_memory_references (loop, sm_in_loop, exits);
+	{
+	  hoist_memory_references (loop, sm_in_loop, exits);
+	  /* Commit edge inserts here to preserve the order of stores
+	     when an exit exits multiple loops.  */
+	  gsi_commit_edge_inserts ();
+	}
     }
   exits.release ();
 
@@ -2915,7 +2921,7 @@ store_motion_loop (class loop *loop, bitmap sm_executed)
    loops.  */
 
 static void
-store_motion (void)
+do_store_motion (void)
 {
   class loop *loop;
   bitmap sm_executed = BITMAP_ALLOC (&lim_bitmap_obstack);
@@ -2924,7 +2930,6 @@ store_motion (void)
     store_motion_loop (loop, sm_executed);
 
   BITMAP_FREE (sm_executed);
-  gsi_commit_edge_inserts ();
 }
 
 /* Fills ALWAYS_EXECUTED_IN information for basic blocks of LOOP, i.e.
@@ -3141,7 +3146,7 @@ tree_ssa_lim (void)
 
   /* Execute store motion.  Force the necessary invariants to be moved
      out of the loops as well.  */
-  store_motion ();
+  do_store_motion ();
 
   /* Move the expressions that are expensive enough.  */
   todo = move_computations ();