Date: Sun, 9 Aug 2015 10:00:14 +0000 (UTC) From: Dimitry Andric <dim@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r286515 - head/lib/msun/src Message-ID: <201508091000.t79A0E4S049442@repo.freebsd.org>
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Author: dim Date: Sun Aug 9 10:00:13 2015 New Revision: 286515 URL: https://svnweb.freebsd.org/changeset/base/286515 Log: In libm's exp2(3), avoid left-shifting a negative integer, which is undefined. Replace it with the intended value, in a defined way. Reviewed by: bde MFC after: 3 days Modified: head/lib/msun/src/s_exp2.c Modified: head/lib/msun/src/s_exp2.c ============================================================================== --- head/lib/msun/src/s_exp2.c Sun Aug 9 09:54:29 2015 (r286514) +++ head/lib/msun/src/s_exp2.c Sun Aug 9 10:00:13 2015 (r286515) @@ -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);
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