poly_int: fold_indirect_ref_1

This patch makes fold_indirect_ref_1 handle polynomial offsets in
a POINTER_PLUS_EXPR.  The specific reason for doing this now is
to handle:

 		  (tree_to_uhwi (part_width) / BITS_PER_UNIT
 		   * TYPE_VECTOR_SUBPARTS (op00type));

when TYPE_VECTOR_SUBPARTS becomes a poly_int.

2018-01-03  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* fold-const.c (fold_indirect_ref_1): Handle polynomial offsets
	in a POINTER_PLUS_EXPR.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>

From-SVN: r256146

gcc/ChangeLog

@@ -2,6 +2,13 @@
 	    Alan Hayward  <alan.hayward@arm.com>
 	    David Sherwood  <david.sherwood@arm.com>
 
+	* fold-const.c (fold_indirect_ref_1): Handle polynomial offsets
+	in a POINTER_PLUS_EXPR.
+
+2018-01-03  Richard Sandiford  <richard.sandiford@linaro.org>
+	    Alan Hayward  <alan.hayward@arm.com>
+	    David Sherwood  <david.sherwood@arm.com>
+
 	* omp-simd-clone.c (simd_clone_subparts): New function.
 	(simd_clone_init_simd_arrays): Use it instead of TYPE_VECTOR_SUBPARTS.
 	(ipa_simd_modify_function_body): Likewise.

gcc/fold-const.c

@@ -14049,6 +14049,7 @@ fold_indirect_ref_1 (location_t loc, tree type, tree op0)
 {
   tree sub = op0;
   tree subtype;
+  poly_uint64 const_op01;
 
   STRIP_NOPS (sub);
   subtype = TREE_TYPE (sub);
@@ -14103,7 +14104,7 @@ fold_indirect_ref_1 (location_t loc, tree type, tree op0)
     }
 
   if (TREE_CODE (sub) == POINTER_PLUS_EXPR
-      && TREE_CODE (TREE_OPERAND (sub, 1)) == INTEGER_CST)
+      && poly_int_tree_p (TREE_OPERAND (sub, 1), &const_op01))
     {
       tree op00 = TREE_OPERAND (sub, 0);
       tree op01 = TREE_OPERAND (sub, 1);
@@ -14120,15 +14121,12 @@ fold_indirect_ref_1 (location_t loc, tree type, tree op0)
 	      && type == TREE_TYPE (op00type))
 	    {
 	      tree part_width = TYPE_SIZE (type);
-	      unsigned HOST_WIDE_INT max_offset
+	      poly_uint64 max_offset
 		= (tree_to_uhwi (part_width) / BITS_PER_UNIT
 		   * TYPE_VECTOR_SUBPARTS (op00type));
-	      if (tree_int_cst_sign_bit (op01) == 0
-		  && compare_tree_int (op01, max_offset) == -1)
+	      if (known_lt (const_op01, max_offset))
 		{
-		  unsigned HOST_WIDE_INT offset = tree_to_uhwi (op01);
-		  unsigned HOST_WIDE_INT indexi = offset * BITS_PER_UNIT;
-		  tree index = bitsize_int (indexi);
+		  tree index = bitsize_int (const_op01 * BITS_PER_UNIT);
 		  return fold_build3_loc (loc,
 					  BIT_FIELD_REF, type, op00,
 					  part_width, index);
@@ -14138,8 +14136,8 @@ fold_indirect_ref_1 (location_t loc, tree type, tree op0)
 	  else if (TREE_CODE (op00type) == COMPLEX_TYPE
 		   && type == TREE_TYPE (op00type))
 	    {
-	      tree size = TYPE_SIZE_UNIT (type);
-	      if (tree_int_cst_equal (size, op01))
+	      if (known_eq (wi::to_poly_offset (TYPE_SIZE_UNIT (type)),
+			    const_op01))
 		return fold_build1_loc (loc, IMAGPART_EXPR, type, op00);
 	    }
 	  /* ((foo *)&fooarray)[1] => fooarray[1] */