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In libm's exp2(3), avoid left-shifting a negative integer, which is

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undefined.  Replace it with the intended value, in a defined way.

Reviewed by:	bde
MFC after:	3 days
This commit is contained in:
Dimitry Andric 2015-08-09 10:00:13 +00:00
parent 4ddb055594
commit a679d056de
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=286515
1 changed files with 2 additions and 2 deletions
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4
lib/msun/src/s_exp2.c
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@ -376,14 +376,14 @@ 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);