From 14cdd65dd256b5734cef5c15ba645e72665ef6f3 Mon Sep 17 00:00:00 2001
From: Catena cyber <35799796+catenacyber@users.noreply.github.com>
Date: Sun, 3 Jun 2018 16:26:12 +0200
Subject: [PATCH] fix undefined shift in countLeadingZeros (#1157)

---
 MathExtras.h | 11 +++++++----
 1 file changed, 7 insertions(+), 4 deletions(-)

diff --git a/MathExtras.h b/MathExtras.h
index db98a2f7..2be6e08a 100644
--- a/MathExtras.h
+++ b/MathExtras.h
@@ -425,14 +425,17 @@ static inline int64_t SignExtend64(uint64_t X, unsigned B) {
 ///   valid arguments.
 static inline unsigned int countLeadingZeros(int x)
 {
-	unsigned count = 0;
 	int i;
 	const unsigned bits = sizeof(x) * 8;
+	unsigned count = bits;
 
+	if (x < 0) {
+		return 0;
+	}
 	for (i = bits; --i; ) {
-		if (x < 0) break;
-		count++;
-		x <<= 1;
+		if (x == 0) break;
+		count--;
+		x >>= 1;
 	}
 
 	return count;