Fix PR66917

Index: gcc/tree-vectorizer.h
===================================================================
--- gcc/tree-vectorizer.h	(revision 226396)
+++ gcc/tree-vectorizer.h	(working copy)
@@ -707,11 +707,16 @@  typedef struct _stmt_vec_info {
 #define STMT_SLP_TYPE(S)                   (S)->slp_type
 
 struct dataref_aux {
-  tree base_decl;
-  bool base_misaligned;
   int misalignment;
+  /* If true the alignment of base_decl needs to be increased.  */
+  bool base_misaligned;
+  /* If true we know the base is at least vector element alignment aligned.  */
+  bool base_element_aligned;
+  tree base_decl;
 };
 
+#define DR_VECT_AUX(dr) ((dataref_aux *)(dr)->aux)
+
 #define VECT_MAX_COST 1000
 
 /* The maximum number of intermediate steps required in multi-step type
@@ -910,14 +915,13 @@  destroy_cost_data (void *data)
   targetm.vectorize.destroy_cost_data (data);
 }
 
-
 /*-----------------------------------------------------------------*/
 /* Info on data references alignment.                              */
 /*-----------------------------------------------------------------*/
 inline void
 set_dr_misalignment (struct data_reference *dr, int val)
 {
-  dataref_aux *data_aux = (dataref_aux *) dr->aux;
+  dataref_aux *data_aux = DR_VECT_AUX (dr);
 
   if (!data_aux)
     {
@@ -931,8 +935,7 @@  set_dr_misalignment (struct data_referen
 inline int
 dr_misalignment (struct data_reference *dr)
 {
-  gcc_assert (dr->aux);
-  return ((dataref_aux *) dr->aux)->misalignment;
+  return DR_VECT_AUX (dr)->misalignment;
 }
 
 /* Reflects actual alignment of first access in the vectorized loop,
Index: gcc/tree-vect-data-refs.c
===================================================================
--- gcc/tree-vect-data-refs.c	(revision 226396)
+++ gcc/tree-vect-data-refs.c	(working copy)
@@ -622,7 +622,6 @@  vect_compute_data_ref_alignment (struct
   tree ref = DR_REF (dr);
   tree vectype;
   tree base, base_addr;
-  bool base_aligned;
   tree misalign = NULL_TREE;
   tree aligned_to;
   unsigned HOST_WIDE_INT alignment;
@@ -698,6 +697,19 @@  vect_compute_data_ref_alignment (struct
 	}
     }
 
+  /* To look at alignment of the base we have to preserve an inner MEM_REF
+     as that carries alignment information of the actual access.  */
+  base = ref;
+  while (handled_component_p (base))
+    base = TREE_OPERAND (base, 0);
+  if (TREE_CODE (base) == MEM_REF)
+    base = build2 (MEM_REF, TREE_TYPE (base), base_addr,
+		   build_int_cst (TREE_TYPE (TREE_OPERAND (base, 1)), 0));
+  unsigned int base_alignment = get_object_alignment (base);
+
+  if (base_alignment >= TYPE_ALIGN (TREE_TYPE (vectype)))
+    DR_VECT_AUX (dr)->base_element_aligned = true;
+
   alignment = TYPE_ALIGN_UNIT (vectype);
 
   if ((compare_tree_int (aligned_to, alignment) < 0)
@@ -713,21 +725,7 @@  vect_compute_data_ref_alignment (struct
       return true;
     }
 
-  /* To look at alignment of the base we have to preserve an inner MEM_REF
-     as that carries alignment information of the actual access.  */
-  base = ref;
-  while (handled_component_p (base))
-    base = TREE_OPERAND (base, 0);
-  if (TREE_CODE (base) == MEM_REF)
-    base = build2 (MEM_REF, TREE_TYPE (base), base_addr,
-		   build_int_cst (TREE_TYPE (TREE_OPERAND (base, 1)), 0));
-
-  if (get_object_alignment (base) >= TYPE_ALIGN (vectype))
-    base_aligned = true;
-  else
-    base_aligned = false;
-
-  if (!base_aligned)
+  if (base_alignment < TYPE_ALIGN (vectype))
     {
       /* Strip an inner MEM_REF to a bare decl if possible.  */
       if (TREE_CODE (base) == MEM_REF
@@ -757,8 +755,9 @@  vect_compute_data_ref_alignment (struct
           dump_printf (MSG_NOTE, "\n");
         }
 
-      ((dataref_aux *)dr->aux)->base_decl = base;
-      ((dataref_aux *)dr->aux)->base_misaligned = true;
+      DR_VECT_AUX (dr)->base_decl = base;
+      DR_VECT_AUX (dr)->base_misaligned = true;
+      DR_VECT_AUX (dr)->base_element_aligned = true;
     }
 
   /* If this is a backward running DR then first access in the larger
Index: gcc/tree-vect-stmts.c
===================================================================
--- gcc/tree-vect-stmts.c	(revision 226396)
+++ gcc/tree-vect-stmts.c	(working copy)
@@ -5056,10 +5056,10 @@  ensure_base_align (stmt_vec_info stmt_in
   if (!dr->aux)
     return;
 
-  if (((dataref_aux *)dr->aux)->base_misaligned)
+  if (DR_VECT_AUX (dr)->base_misaligned)
     {
       tree vectype = STMT_VINFO_VECTYPE (stmt_info);
-      tree base_decl = ((dataref_aux *)dr->aux)->base_decl;
+      tree base_decl = DR_VECT_AUX (dr)->base_decl;
 
       if (decl_in_symtab_p (base_decl))
 	symtab_node::get (base_decl)->increase_alignment (TYPE_ALIGN (vectype));
@@ -5068,7 +5068,7 @@  ensure_base_align (stmt_vec_info stmt_in
           DECL_ALIGN (base_decl) = TYPE_ALIGN (vectype);
           DECL_USER_ALIGN (base_decl) = 1;
 	}
-      ((dataref_aux *)dr->aux)->base_misaligned = false;
+      DR_VECT_AUX (dr)->base_misaligned = false;
     }
 }
 
@@ -5739,11 +5739,15 @@  vectorizable_store (gimple stmt, gimple_
 		misalign = 0;
 	      else if (DR_MISALIGNMENT (first_dr) == -1)
 		{
+		  if (DR_VECT_AUX (first_dr)->base_element_aligned)
+		    align = TYPE_ALIGN_UNIT (elem_type);
+		  else
+		    align = get_object_alignment (DR_REF (first_dr))
+			/ BITS_PER_UNIT;
+		  misalign = 0;
 		  TREE_TYPE (data_ref)
 		    = build_aligned_type (TREE_TYPE (data_ref),
-					  TYPE_ALIGN (elem_type));
-		  align = TYPE_ALIGN_UNIT (elem_type);
-		  misalign = 0;
+					  align * BITS_PER_UNIT);
 		}
 	      else
 		{
@@ -6824,11 +6828,15 @@  vectorizable_load (gimple stmt, gimple_s
 		      }
 		    else if (DR_MISALIGNMENT (first_dr) == -1)
 		      {
+			if (DR_VECT_AUX (first_dr)->base_element_aligned)
+			  align = TYPE_ALIGN_UNIT (elem_type);
+			else
+			  align = (get_object_alignment (DR_REF (first_dr))
+				   / BITS_PER_UNIT);
+			misalign = 0;
 			TREE_TYPE (data_ref)
 			  = build_aligned_type (TREE_TYPE (data_ref),
-						TYPE_ALIGN (elem_type));
-			align = TYPE_ALIGN_UNIT (elem_type);
-			misalign = 0;
+						align * BITS_PER_UNIT);
 		      }
 		    else
 		      {