From: Aldy Hernandez <aldyh@redhat.com>
Date: Tue, 20 Oct 2020 06:53:21 +0000 (+0200)
Subject: Special case shifting by zero in operator_rshift::op1_range.
X-Git-Tag: basepoints/gcc-12~4142
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=f0c0f124ebe28b71abccbd7247678c9ac608b649;p=thirdparty%2Fgcc.git

Special case shifting by zero in operator_rshift::op1_range.

gcc/ChangeLog:

	* range-op.cc (operator_rshift::op1_range): Special case
	shifting by zero.
---

diff --git a/gcc/range-op.cc b/gcc/range-op.cc
index 21d98de22406..ee62f103598a 100644
--- a/gcc/range-op.cc
+++ b/gcc/range-op.cc
@@ -1642,6 +1642,11 @@ operator_rshift::op1_range (irange &r,
 		    wi::uhwi (prec, TYPE_PRECISION (TREE_TYPE (shift))),
 		    UNSIGNED))
 	return false;
+      if (wi::to_wide (shift) == 0)
+	{
+	  r = lhs;
+	  return true;
+	}
 
       // Folding the original operation may discard some impossible
       // ranges from the LHS.