Date: Sun, 8 Jul 2018 16:33:59 +0000 (UTC) From: Mark Johnston <markj@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r336090 - head/lib/msun/src Message-ID: <201807081633.w68GXxDe066982@repo.freebsd.org>
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Author: markj Date: Sun Jul 8 16:33:58 2018 New Revision: 336090 URL: https://svnweb.freebsd.org/changeset/base/336090 Log: Reduce diff between msun/src/e_pow.c and msun/src/e_powf.c. Remove unnecessary casts, use integer literal constants instead of floating point constants where possible, and introduce three const static variables to hold 0.5, 0.25, and 1/3. PR: 229420 Submitted by: Steve Kargl <sgk@troutmask.apl.washington.edu> MFC after: 1 week Modified: head/lib/msun/src/e_pow.c head/lib/msun/src/e_powf.c Modified: head/lib/msun/src/e_pow.c ============================================================================== --- head/lib/msun/src/e_pow.c Sun Jul 8 16:26:13 2018 (r336089) +++ head/lib/msun/src/e_pow.c Sun Jul 8 16:33:58 2018 (r336090) @@ -65,6 +65,9 @@ bp[] = {1.0, 1.5,}, dp_h[] = { 0.0, 5.84962487220764160156e-01,}, /* 0x3FE2B803, 0x40000000 */ dp_l[] = { 0.0, 1.35003920212974897128e-08,}, /* 0x3E4CFDEB, 0x43CFD006 */ zero = 0.0, +half = 0.5, +qrtr = 0.25, +thrd = 3.3333333333333331e-01, /* 0x3fd55555, 0x55555555 */ one = 1.0, two = 2.0, two53 = 9007199254740992.0, /* 0x43400000, 0x00000000 */ @@ -197,7 +200,7 @@ __ieee754_pow(double x, double y) /* now |1-x| is tiny <= 2**-20, suffice to compute log(x) by x-x^2/2+x^3/3-x^4/4 */ t = ax-one; /* t has 20 trailing zeros */ - w = (t*t)*(0.5-t*(0.3333333333333333333333-t*0.25)); + w = (t*t)*(half-t*(thrd-t*qrtr)); u = ivln2_h*t; /* ivln2_h has 21 sig. bits */ v = t*ivln2_l-w*ivln2; t1 = u+v; @@ -234,9 +237,9 @@ __ieee754_pow(double x, double y) r = s2*s2*(L1+s2*(L2+s2*(L3+s2*(L4+s2*(L5+s2*L6))))); r += s_l*(s_h+ss); s2 = s_h*s_h; - t_h = 3.0+s2+r; + t_h = 3+s2+r; SET_LOW_WORD(t_h,0); - t_l = r-((t_h-3.0)-s2); + t_l = r-((t_h-3)-s2); /* u+v = ss*(1+...) */ u = s_h*t_h; v = s_l*t_h+t_l*ss; @@ -247,7 +250,7 @@ __ieee754_pow(double x, double y) z_h = cp_h*p_h; /* cp_h+cp_l = 2/(3*log2) */ z_l = cp_l*p_h+p_l*cp+dp_l[k]; /* log2(ax) = (ss+..)*2/(3*log2) = n + dp_h + z_h + z_l */ - t = (double)n; + t = n; t1 = (((z_h+z_l)+dp_h[k])+t); SET_LOW_WORD(t1,0); t2 = z_l-(((t1-t)-dp_h[k])-z_h); Modified: head/lib/msun/src/e_powf.c ============================================================================== --- head/lib/msun/src/e_powf.c Sun Jul 8 16:26:13 2018 (r336089) +++ head/lib/msun/src/e_powf.c Sun Jul 8 16:33:58 2018 (r336090) @@ -24,6 +24,9 @@ bp[] = {1.0, 1.5,}, dp_h[] = { 0.0, 5.84960938e-01,}, /* 0x3f15c000 */ dp_l[] = { 0.0, 1.56322085e-06,}, /* 0x35d1cfdc */ zero = 0.0, +half = 0.5, +qrtr = 0.25, +thrd = 3.33333343e-01, /* 0x3eaaaaab */ one = 1.0, two = 2.0, two24 = 16777216.0, /* 0x4b800000 */ @@ -138,7 +141,7 @@ __ieee754_powf(float x, float y) /* now |1-x| is tiny <= 2**-20, suffice to compute log(x) by x-x^2/2+x^3/3-x^4/4 */ t = ax-1; /* t has 20 trailing zeros */ - w = (t*t)*((float)0.5-t*((float)0.333333333333-t*(float)0.25)); + w = (t*t)*(half-t*(thrd-t*qrtr)); u = ivln2_h*t; /* ivln2_h has 16 sig. bits */ v = t*ivln2_l-w*ivln2; t1 = u+v; @@ -177,10 +180,10 @@ __ieee754_powf(float x, float y) r = s2*s2*(L1+s2*(L2+s2*(L3+s2*(L4+s2*(L5+s2*L6))))); r += s_l*(s_h+s); s2 = s_h*s_h; - t_h = (float)3.0+s2+r; + t_h = 3+s2+r; GET_FLOAT_WORD(is,t_h); SET_FLOAT_WORD(t_h,is&0xfffff000); - t_l = r-((t_h-(float)3.0)-s2); + t_l = r-((t_h-3)-s2); /* u+v = s*(1+...) */ u = s_h*t_h; v = s_l*t_h+t_l*s; @@ -192,7 +195,7 @@ __ieee754_powf(float x, float y) z_h = cp_h*p_h; /* cp_h+cp_l = 2/(3*log2) */ z_l = cp_l*p_h+p_l*cp+dp_l[k]; /* log2(ax) = (s+..)*2/(3*log2) = n + dp_h + z_h + z_l */ - t = (float)n; + t = n; t1 = (((z_h+z_l)+dp_h[k])+t); GET_FLOAT_WORD(is,t1); SET_FLOAT_WORD(t1,is&0xfffff000);
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