Avoid left shift of negative value in ipa-modref-tree.h

gcc/ChangeLog:

	PR ipa/103082
	* ipa-modref-tree.h (struct modref_access_node): Avoid left shift
	of negative value

diff --git a/gcc/ipa-modref-tree.h b/gcc/ipa-modref-tree.h
index 9976e48..bc428d1 100644 (file)
--- a/gcc/ipa-modref-tree.h
+++ b/gcc/ipa-modref-tree.h
@@ -116,8 +116,13 @@ struct GTY(()) modref_access_node
               if (!known_le (parm_offset, a.parm_offset)
                   && !range_info_useful_p ())
                 return false;
+              /* We allow negative aoffset_adj here in case
+                 there is an useful range.  This is because adding
+                 a.offset may result in non-ngative offset again.
+                 Ubsan fails on val << LOG_BITS_PER_UNIT where val
+                 is negative.  */
               aoffset_adj = (a.parm_offset - parm_offset)
-                            << LOG2_BITS_PER_UNIT;
+                            * BITS_PER_UNIT;
            }
        }
       if (range_info_useful_p ())