From: Andrew MacLeod <amacleod@redhat.com>
Date: Mon, 31 Oct 2022 13:53:01 +0000 (-0400)
Subject: Intersect with nonzero bits can indicate change incorrectly.
X-Git-Tag: basepoints/gcc-14~3614
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=7cc2824e39440dd71a9d2832c51ef260bb36d8ca;p=thirdparty%2Fgcc.git

Intersect with nonzero bits can indicate change incorrectly.

	* value-range.cc (irange::intersect_nonzero_bits): If new
	non-zero mask is the same as original, flag no change.
---

diff --git a/gcc/value-range.cc b/gcc/value-range.cc
index 03b3c4b4a65d..3743ec714b31 100644
--- a/gcc/value-range.cc
+++ b/gcc/value-range.cc
@@ -3017,6 +3017,10 @@ irange::intersect_nonzero_bits (const irange &r)
   if (mask_to_wi (m_nonzero_mask, t) != mask_to_wi (r.m_nonzero_mask, t))
     {
       wide_int nz = get_nonzero_bits () & r.get_nonzero_bits ();
+      // If the nonzero bits did not change, return false.
+      if (nz == get_nonzero_bits ())
+	return false;
+
       m_nonzero_mask = wide_int_to_tree (t, nz);
       if (set_range_from_nonzero_bits ())
 	return true;