re PR lto/83338 (SPEC CPU2017 510.parest_r ICE)

	PR tree-optimization/83338
	* tree-vect-stmts.c (vectorizable_operation): Handle POINTER_DIFF_EXPR
	vectorization as MINUS_EXPR with a subsequent VIEW_CONVERT_EXPR from
	vector of unsigned integers to vector of signed integers.

	* gcc.dg/vect/pr83338.c: New test.

From-SVN: r255523

gcc/ChangeLog

+2017-12-09  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/83338
+	* tree-vect-stmts.c (vectorizable_operation): Handle POINTER_DIFF_EXPR
+	vectorization as MINUS_EXPR with a subsequent VIEW_CONVERT_EXPR from
+	vector of unsigned integers to vector of signed integers.
+
 2017-12-08  Vladimir Makarov  <vmakarov@redhat.com>
 
 	PR rtl-optimization/83317

gcc/testsuite/ChangeLog

+2017-12-09  Jakub Jelinek  <jakub@redhat.com>
+
+	PR tree-optimization/83338
+	* gcc.dg/vect/pr83338.c: New test.
+
 2017-12-09  Thomas Koenig  <tkoenig@gcc.gnu.org>
 
 	PR fortran/83316

gcc/testsuite/gcc.dg/vect/pr83338.c

+/* PR tree-optimization/83338 */
+/* { dg-do compile } */
+
+void
+foo (char **p, char **q, __PTRDIFF_TYPE__ *r)
+{
+  int i;
+  for (i = 0; i < 1024; i++)
+    r[i] = p[i] - q[i];
+}

gcc/tree-vect-stmts.c

@@ -5226,7 +5226,7 @@ vectorizable_operation (gimple *stmt, gimple_stmt_iterator *gsi,
   stmt_vec_info stmt_info = vinfo_for_stmt (stmt);
   tree vectype;
   loop_vec_info loop_vinfo = STMT_VINFO_LOOP_VINFO (stmt_info);
-  enum tree_code code;
+  enum tree_code code, orig_code;
   machine_mode vec_mode;
   tree new_temp;
   int op_type;
@@ -5264,7 +5264,7 @@ vectorizable_operation (gimple *stmt, gimple_stmt_iterator *gsi,
   if (TREE_CODE (gimple_assign_lhs (stmt)) != SSA_NAME)
     return false;
 
-  code = gimple_assign_rhs_code (stmt);
+  orig_code = code = gimple_assign_rhs_code (stmt);
 
   /* For pointer addition and subtraction, we should use the normal
      plus and minus for the vector operation.  */
@@ -5455,6 +5455,14 @@ vectorizable_operation (gimple *stmt, gimple_stmt_iterator *gsi,
   /* Handle def.  */
   vec_dest = vect_create_destination_var (scalar_dest, vectype);
 
+  /* POINTER_DIFF_EXPR has pointer arguments which are vectorized as
+     vectors with unsigned elements, but the result is signed.  So, we
+     need to compute the MINUS_EXPR into vectype temporary and
+     VIEW_CONVERT_EXPR it into the final vectype_out result.  */
+  tree vec_cvt_dest = NULL_TREE;
+  if (orig_code == POINTER_DIFF_EXPR)
+    vec_cvt_dest = vect_create_destination_var (scalar_dest, vectype_out);
+
   /* In case the vectorization factor (VF) is bigger than the number
      of elements that we can fit in a vectype (nunits), we have to generate
      more than one vector stmt - i.e - we need to "unroll" the
@@ -5546,6 +5554,15 @@ vectorizable_operation (gimple *stmt, gimple_stmt_iterator *gsi,
 	  new_temp = make_ssa_name (vec_dest, new_stmt);
 	  gimple_assign_set_lhs (new_stmt, new_temp);
 	  vect_finish_stmt_generation (stmt, new_stmt, gsi);
+	  if (vec_cvt_dest)
+	    {
+	      new_temp = build1 (VIEW_CONVERT_EXPR, vectype_out, new_temp);
+	      new_stmt = gimple_build_assign (vec_cvt_dest, VIEW_CONVERT_EXPR,
+					      new_temp);
+	      new_temp = make_ssa_name (vec_cvt_dest, new_stmt);
+	      gimple_assign_set_lhs (new_stmt, new_temp);
+	      vect_finish_stmt_generation (stmt, new_stmt, gsi);
+	    }
           if (slp_node)
 	    SLP_TREE_VEC_STMTS (slp_node).quick_push (new_stmt);
         }