From bdd8abc6d6a93ce3ab8ad5db716222ee3110c4a3 Mon Sep 17 00:00:00 2001
From: "Pedro F. Giffuni" <pfg@FreeBSD.org>
Date: Mon, 7 Jan 2019 17:35:09 +0000
Subject: [PATCH] pow(3): Workaround possible signed shift Undefined Behavior.

j is int32_t and thus j<<31 is undefined if j==1.

Hinted by:	muusl-lib (git 688d3da0f1730daddbc954bbc2d27cc96ceee04c)
Discussed with:	freebsd-numerics (kargl)
---
 lib/msun/src/e_pow.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/msun/src/e_pow.c b/lib/msun/src/e_pow.c
index 69ddb7ffcb48..52b2f5cebdbc 100644
--- a/lib/msun/src/e_pow.c
+++ b/lib/msun/src/e_pow.c
@@ -133,7 +133,7 @@ __ieee754_pow(double x, double y)
 		k = (iy>>20)-0x3ff;	   /* exponent */
 		if(k>20) {
 		    j = ly>>(52-k);
-		    if((j<<(52-k))==ly) yisint = 2-(j&1);
+		    if(((u_int32_t)j<<(52-k))==ly) yisint = 2-(j&1);
 		} else if(ly==0) {
 		    j = iy>>(20-k);
 		    if((j<<(20-k))==iy) yisint = 2-(j&1);