Fix UBSAN errors in dse.c (PR rtl-optimization/82044).

2017-11-21  Martin Liska  <mliska@suse.cz>

	PR rtl-optimization/82044
	PR tree-optimization/82042
	* dse.c (check_mem_read_rtx): Check for overflow.

From-SVN: r255001

1 files changed, 6 insertions, 0 deletions

diff --git a/gcc/dse.c b/gcc/dse.c
index 563ca9f..f6d5e6e 100644
--- a/gcc/dse.c
+++ b/gcc/dse.c
@@ -1981,6 +1981,12 @@ check_mem_read_rtx (rtx *loc, bb_info_t bb_info)
   else
     width = GET_MODE_SIZE (GET_MODE (mem));
 
+  if (offset > HOST_WIDE_INT_MAX - width)
+    {
+      clear_rhs_from_active_local_stores ();
+      return;
+    }
+
   read_info = read_info_type_pool.allocate ();
   read_info->group_id = group_id;
   read_info->mem = mem;