I saw this drifting by on FreeBSD (from Dimitry Andric):
In libm's exp2(3), avoid left-shifting a negative integer, which is
undefined. Replace it with the intended value, in a defined way.
OK? Don't bother?
Index: src/s_exp2.c
===================================================================
RCS file: /cvs/src/lib/libm/src/s_exp2.c,v
retrieving revision 1.7
diff -u -p -r1.7 s_exp2.c
--- src/s_exp2.c 3 Jul 2013 04:46:36 -0000 1.7
+++ src/s_exp2.c 19 Aug 2015 19:10:38 -0000
@@ -373,14 +373,14 @@ exp2(double x)
/* Compute r = exp2(y) = exp2t[i0] * p(z - eps[i]). */
t = tbl[i0]; /* exp2t[i0] */
z -= tbl[i0 + 1]; /* eps[i0] */
- if (k >= -1021 << 20)
+ if (k >= -(1021 << 20))
INSERT_WORDS(twopk, 0x3ff00000 + k, 0);
else
INSERT_WORDS(twopkp1000, 0x3ff00000 + k + (1000 << 20), 0);
r = t + t * z * (P1 + z * (P2 + z * (P3 + z * (P4 + z * P5))));
/* Scale by 2**(k>>20). */
- if(k >= -1021 << 20) {
+ if(k >= -(1021 << 20)) {
if (k == 1024 << 20)
return (r * 2.0 * 0x1p1023);
return (r * twopk);
--
Christian "naddy" Weisgerber [email protected]
