tree-vect-data-refs.c (vect_enhance_data_refs_alignment): When all DRs have…

tree-vect-data-refs.c (vect_enhance_data_refs_alignment): When all DRs have unknown misaligned do not always peel when...

2017-05-03  Richard Biener  <rguenther@suse.de>

	* tree-vect-data-refs.c (vect_enhance_data_refs_alignment):
	When all DRs have unknown misaligned do not always peel
	when there is a store but apply the same costing model as if
	there were only loads.

	* gcc.dg/vect/costmodel/x86_64/costmodel-alignpeel.c: New testcase.

From-SVN: r247544

gcc/ChangeLog

 2017-05-03  Richard Biener  <rguenther@suse.de>
 
+	* tree-vect-data-refs.c (vect_enhance_data_refs_alignment):
+	When all DRs have unknown misaligned do not always peel
+	when there is a store but apply the same costing model as if
+	there were only loads.
+
+2017-05-03  Richard Biener  <rguenther@suse.de>
+
 	Revert
 	PR tree-optimization/80492
 	* tree-ssa-alias.c (decl_refs_may_alias_p): Handle

gcc/testsuite/ChangeLog

+2017-05-03  Richard Biener  <rguenther@suse.de>
+
+	* gcc.dg/vect/costmodel/x86_64/costmodel-alignpeel.c: New testcase.
+
 2017-05-03  Jakub Jelinek  <jakub@redhat.com>
 
 	PR tree-optimization/79472

gcc/testsuite/gcc.dg/vect/costmodel/x86_64/costmodel-alignpeel.c

+/* { dg-do compile } */
+
+void func(double * __restrict__ v1, double * v2, unsigned n)
+{
+  for (unsigned i = 0; i < n; ++i)
+    v1[i] = v2[i];
+}
+
+/* { dg-final { scan-tree-dump-not "Alignment of access forced using peeling" "vect" } } */

gcc/tree-vect-data-refs.c

@@ -1715,18 +1715,18 @@ vect_enhance_data_refs_alignment (loop_vec_info loop_vinfo)
             dr0 = first_store;
         }
 
-      /* In case there are only loads with different unknown misalignments, use
-         peeling only if it may help to align other accesses in the loop or
+      /* Use peeling only if it may help to align other accesses in the loop or
 	 if it may help improving load bandwith when we'd end up using
 	 unaligned loads.  */
       tree dr0_vt = STMT_VINFO_VECTYPE (vinfo_for_stmt (DR_STMT (dr0)));
-      if (!first_store
-	  && !STMT_VINFO_SAME_ALIGN_REFS (
-		  vinfo_for_stmt (DR_STMT (dr0))).length ()
+      if (STMT_VINFO_SAME_ALIGN_REFS
+	    (vinfo_for_stmt (DR_STMT (dr0))).length () == 0
 	  && (vect_supportable_dr_alignment (dr0, false)
 	      != dr_unaligned_supported
-	      || (builtin_vectorization_cost (vector_load, dr0_vt, 0)
-		  == builtin_vectorization_cost (unaligned_load, dr0_vt, -1))))
+	      || (DR_IS_READ (dr0)
+		  && (builtin_vectorization_cost (vector_load, dr0_vt, 0)
+		      == builtin_vectorization_cost (unaligned_load,
+						     dr0_vt, -1)))))
         do_peeling = false;
     }