poly_int: symbolic_number

This patch changes symbol_number::bytepos from a HOST_WIDE_INT
to a poly_int64.  perform_symbolic_merge can cope with symbolic
offsets as long as the difference between the two offsets is
constant.  (This could happen for a constant-sized field that
occurs at a variable offset, for example.)

2017-12-20  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* gimple-ssa-store-merging.c (symbolic_number::bytepos): Change from
	HOST_WIDE_INT to poly_int64_pod.
	(perform_symbolic_merge): Update accordingly.
	(bswap_replace): Likewise.

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

From-SVN: r255889

gcc/ChangeLog

@@ -2,6 +2,15 @@
 	    Alan Hayward  <alan.hayward@arm.com>
 	    David Sherwood  <david.sherwood@arm.com>
 
+	* gimple-ssa-store-merging.c (symbolic_number::bytepos): Change from
+	HOST_WIDE_INT to poly_int64_pod.
+	(perform_symbolic_merge): Update accordingly.
+	(bswap_replace): Likewise.
+
+2017-12-20  Richard Sandiford  <richard.sandiford@linaro.org>
+	    Alan Hayward  <alan.hayward@arm.com>
+	    David Sherwood  <david.sherwood@arm.com>
+
 	* tree-affine.h (aff_tree::offset): Change from widest_int
 	to poly_widest_int.
 	(wide_int_ext_for_comb): Delete.

gcc/gimple-ssa-store-merging.c

@@ -216,7 +216,7 @@ struct symbolic_number {
   tree type;
   tree base_addr;
   tree offset;
-  HOST_WIDE_INT bytepos;
+  poly_int64_pod bytepos;
   tree src;
   tree alias_set;
   tree vuse;
@@ -452,7 +452,7 @@ perform_symbolic_merge (gimple *source_stmt1, struct symbolic_number *n1,
   if (rhs1 != rhs2)
     {
       uint64_t inc;
-      HOST_WIDE_INT start_sub, end_sub, end1, end2, end;
+      HOST_WIDE_INT start1, start2, start_sub, end_sub, end1, end2, end;
       struct symbolic_number *toinc_n_ptr, *n_end;
       basic_block bb1, bb2;
 
@@ -464,15 +464,19 @@ perform_symbolic_merge (gimple *source_stmt1, struct symbolic_number *n1,
 	  || (n1->offset && !operand_equal_p (n1->offset, n2->offset, 0)))
 	return NULL;
 
-      if (n1->bytepos < n2->bytepos)
+      start1 = 0;
+      if (!(n2->bytepos - n1->bytepos).is_constant (&start2))
+	return NULL;
+
+      if (start1 < start2)
 	{
 	  n_start = n1;
-	  start_sub = n2->bytepos - n1->bytepos;
+	  start_sub = start2 - start1;
 	}
       else
 	{
 	  n_start = n2;
-	  start_sub = n1->bytepos - n2->bytepos;
+	  start_sub = start1 - start2;
 	}
 
       bb1 = gimple_bb (source_stmt1);
@@ -484,8 +488,8 @@ perform_symbolic_merge (gimple *source_stmt1, struct symbolic_number *n1,
 
       /* Find the highest address at which a load is performed and
 	 compute related info.  */
-      end1 = n1->bytepos + (n1->range - 1);
-      end2 = n2->bytepos + (n2->range - 1);
+      end1 = start1 + (n1->range - 1);
+      end2 = start2 + (n2->range - 1);
       if (end1 < end2)
 	{
 	  end = end2;
@@ -504,7 +508,7 @@ perform_symbolic_merge (gimple *source_stmt1, struct symbolic_number *n1,
       else
 	toinc_n_ptr = (n_start == n1) ? n2 : n1;
 
-      n->range = end - n_start->bytepos + 1;
+      n->range = end - MIN (start1, start2) + 1;
 
       /* Check that the range of memory covered can be represented by
 	 a symbolic number.  */
@@ -933,7 +937,7 @@ bswap_replace (gimple_stmt_iterator gsi, gimple *ins_stmt, tree fndecl,
       tree load_offset_ptr, aligned_load_type;
       gimple *load_stmt;
       unsigned align = get_object_alignment (src);
-      HOST_WIDE_INT load_offset = 0;
+      poly_int64 load_offset = 0;
 
       if (cur_stmt)
 	{