From: Jan Hubicka <hubicka@ucw.cz>
Date: Fri, 5 Nov 2021 22:17:50 +0000 (+0100)
Subject: Avoid left shift of negative value in ipa-modref-tree.h
X-Git-Tag: basepoints/gcc-13~3348
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9cc8ca8da90426f625481195a2127a5e86689bcd;p=thirdparty%2Fgcc.git

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 9976e489697e..bc428d193d24 100644
--- 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 ())