Date: Sun, 16 Oct 2011 05:37:02 +0000 (UTC) From: David Schultz <das@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r226413 - head/lib/msun/src Message-ID: <201110160537.p9G5b2x0047181@svn.freebsd.org>
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Author: das Date: Sun Oct 16 05:37:01 2011 New Revision: 226413 URL: http://svn.freebsd.org/changeset/base/226413 Log: Optimize the case of pure imaginary arguments. Calls like this are common, e.g., in DFT implementations. Discussed with: bde, kargl Modified: head/lib/msun/src/s_cexp.c head/lib/msun/src/s_cexpf.c Modified: head/lib/msun/src/s_cexp.c ============================================================================== --- head/lib/msun/src/s_cexp.c Sun Oct 16 05:36:39 2011 (r226412) +++ head/lib/msun/src/s_cexp.c Sun Oct 16 05:37:01 2011 (r226413) @@ -56,8 +56,12 @@ cexp(double complex z) /* cexp(x + I 0) = exp(x) + I 0 */ if ((hy | ly) == 0) return (cpack(exp(x), y)); + EXTRACT_WORDS(hx, lx, x); + /* cexp(0 + I y) = cos(y) + I sin(y) */ + if (((hx & 0x7fffffff) | lx) == 0) + return (cpack(cos(y), sin(y))); + if (hy >= 0x7ff00000) { - EXTRACT_WORDS(hx, lx, x); if (lx != 0 || (hx & 0x7fffffff) != 0x7ff00000) { /* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */ return (cpack(y - y, y - y)); @@ -70,7 +74,6 @@ cexp(double complex z) } } - GET_HIGH_WORD(hx, x); if (hx >= exp_ovfl && hx <= cexp_ovfl) { /* * x is between 709.7 and 1454.3, so we must scale to avoid Modified: head/lib/msun/src/s_cexpf.c ============================================================================== --- head/lib/msun/src/s_cexpf.c Sun Oct 16 05:36:39 2011 (r226412) +++ head/lib/msun/src/s_cexpf.c Sun Oct 16 05:37:01 2011 (r226413) @@ -57,6 +57,10 @@ cexpf(float complex z) if (hy == 0) return (cpackf(expf(x), y)); GET_FLOAT_WORD(hx, x); + /* cexp(0 + I y) = cos(y) + I sin(y) */ + if ((hx & 0x7fffffff) == 0) + return (cpackf(cosf(y), sinf(y))); + if (hy >= 0x7f800000) { if ((hx & 0x7fffffff) != 0x7f800000) { /* cexp(finite|NaN +- I Inf|NaN) = NaN + I NaN */
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