re PR tree-optimization/84946 (UBSAN: in mem_valid_for_store_merging…

re PR tree-optimization/84946 (UBSAN: in mem_valid_for_store_merging ../../gcc/gimple-ssa-store-merging.c:3951)

	PR tree-optimization/84946
	* gimple-ssa-store-merging.c (mem_valid_for_store_merging): Compute
	bitsize + bitsize in poly_uint64 rather than poly_int64.

From-SVN: r258665

gcc/ChangeLog

 2018-03-19  Jakub Jelinek  <jakub@redhat.com>
 
+	PR tree-optimization/84946
+	* gimple-ssa-store-merging.c (mem_valid_for_store_merging): Compute
+	bitsize + bitsize in poly_uint64 rather than poly_int64.
+
 	PR sanitizer/78651
 	* dwarf2asm.c: Include fold-const.c.
 	(dw2_output_indirect_constant_1): Set DECL_INITIAL (decl) to ADDR_EXPR

gcc/gimple-ssa-store-merging.c

@@ -3948,7 +3948,8 @@ mem_valid_for_store_merging (tree mem, poly_uint64 *pbitsize,
   if (known_eq (bitregion_end, 0U))
     {
       bitregion_start = round_down_to_byte_boundary (bitpos);
-      bitregion_end = round_up_to_byte_boundary (bitpos + bitsize);
+      bitregion_end = bitpos;
+      bitregion_end = round_up_to_byte_boundary (bitregion_end + bitsize);
     }
 
   if (offset != NULL_TREE)