Add Go frontend, libgo library, and Go testsuite.

gcc/:
	* gcc.c (default_compilers): Add entry for ".go".
	* common.opt: Add -static-libgo as a driver option.
	* doc/install.texi (Configuration): Mention libgo as an option for
	--enable-shared.  Mention go as an option for --enable-languages.
	* doc/invoke.texi (Overall Options): Mention .go as a file name
	suffix.  Mention go as a -x option.
	* doc/frontends.texi (G++ and GCC): Mention Go as a supported
	language.
	* doc/sourcebuild.texi (Top Level): Mention libgo.
	* doc/standards.texi (Standards): Add section on Go language.
	Move references for other languages into their own section.
	* doc/contrib.texi (Contributors): Mention that I contributed the
	Go frontend.
gcc/testsuite/:
	* lib/go.exp: New file.
	* lib/go-dg.exp: New file.
	* lib/go-torture.exp: New file.
	* lib/target-supports.exp (check_compile): Match // Go.

From-SVN: r167407

1 files changed, 200 insertions, 0 deletions

diff --git a/libgo/go/math/log1p.go b/libgo/go/math/log1p.go
new file mode 100644
index 0000000..e1fc275
--- /dev/null
+++ b/libgo/go/math/log1p.go
@@ -0,0 +1,200 @@
+// Copyright 2010 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package math
+
+
+// The original C code, the long comment, and the constants
+// below are from FreeBSD's /usr/src/lib/msun/src/s_log1p.c
+// and came with this notice.  The go code is a simplified
+// version of the original C.
+//
+// ====================================================
+// Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved.
+//
+// Developed at SunPro, a Sun Microsystems, Inc. business.
+// Permission to use, copy, modify, and distribute this
+// software is freely granted, provided that this notice
+// is preserved.
+// ====================================================
+//
+//
+// double log1p(double x)
+//
+// Method :
+//   1. Argument Reduction: find k and f such that
+//                      1+x = 2**k * (1+f),
+//         where  sqrt(2)/2 < 1+f < sqrt(2) .
+//
+//      Note. If k=0, then f=x is exact. However, if k!=0, then f
+//      may not be representable exactly. In that case, a correction
+//      term is need. Let u=1+x rounded. Let c = (1+x)-u, then
+//      log(1+x) - log(u) ~ c/u. Thus, we proceed to compute log(u),
+//      and add back the correction term c/u.
+//      (Note: when x > 2**53, one can simply return log(x))
+//
+//   2. Approximation of log1p(f).
+//      Let s = f/(2+f) ; based on log(1+f) = log(1+s) - log(1-s)
+//               = 2s + 2/3 s**3 + 2/5 s**5 + .....,
+//               = 2s + s*R
+//      We use a special Reme algorithm on [0,0.1716] to generate
+//      a polynomial of degree 14 to approximate R The maximum error
+//      of this polynomial approximation is bounded by 2**-58.45. In
+//      other words,
+//                      2      4      6      8      10      12      14
+//          R(z) ~ Lp1*s +Lp2*s +Lp3*s +Lp4*s +Lp5*s  +Lp6*s  +Lp7*s
+//      (the values of Lp1 to Lp7 are listed in the program)
+//      a-0.2929nd
+//          |      2          14          |     -58.45
+//          | Lp1*s +...+Lp7*s    -  R(z) | <= 2
+//          |                             |
+//      Note that 2s = f - s*f = f - hfsq + s*hfsq, where hfsq = f*f/2.
+//      In order to guarantee error in log below 1ulp, we compute log
+//      by
+//              log1p(f) = f - (hfsq - s*(hfsq+R)).
+//
+//   3. Finally, log1p(x) = k*ln2 + log1p(f).
+//                        = k*ln2_hi+(f-(hfsq-(s*(hfsq+R)+k*ln2_lo)))
+//      Here ln2 is split into two floating point number:
+//                   ln2_hi + ln2_lo,
+//      where n*ln2_hi is always exact for |n| < 2000.
+//
+// Special cases:
+//      log1p(x) is NaN with signal if x < -1 (including -INF) ;
+//      log1p(+INF) is +INF; log1p(-1) is -INF with signal;
+//      log1p(NaN) is that NaN with no signal.
+//
+// Accuracy:
+//      according to an error analysis, the error is always less than
+//      1 ulp (unit in the last place).
+//
+// Constants:
+// The hexadecimal values are the intended ones for the following
+// constants. The decimal values may be used, provided that the
+// compiler will convert from decimal to binary accurately enough
+// to produce the hexadecimal values shown.
+//
+// Note: Assuming log() return accurate answer, the following
+//       algorithm can be used to compute log1p(x) to within a few ULP:
+//
+//              u = 1+x;
+//              if(u==1.0) return x ; else
+//                         return log(u)*(x/(u-1.0));
+//
+//       See HP-15C Advanced Functions Handbook, p.193.
+
+// Log1p returns the natural logarithm of 1 plus its argument x.
+// It is more accurate than Log(1 + x) when x is near zero.
+//
+// Special cases are:
+//	Log1p(+Inf) = +Inf
+//	Log1p(-1) = -Inf
+//	Log1p(x < -1) = NaN
+//	Log1p(NaN) = NaN
+func Log1p(x float64) float64 {
+	const (
+		Sqrt2M1     = 4.142135623730950488017e-01  // Sqrt(2)-1 = 0x3fda827999fcef34
+		Sqrt2HalfM1 = -2.928932188134524755992e-01 // Sqrt(2)/2-1 = 0xbfd2bec333018866
+		Small       = 1.0 / (1 << 29)              // 2**-29 = 0x3e20000000000000
+		Tiny        = 1.0 / (1 << 54)              // 2**-54
+		Two53       = 1 << 53                      // 2**53
+		Ln2Hi       = 6.93147180369123816490e-01   // 3fe62e42fee00000
+		Ln2Lo       = 1.90821492927058770002e-10   // 3dea39ef35793c76
+		Lp1         = 6.666666666666735130e-01     // 3FE5555555555593
+		Lp2         = 3.999999999940941908e-01     // 3FD999999997FA04
+		Lp3         = 2.857142874366239149e-01     // 3FD2492494229359
+		Lp4         = 2.222219843214978396e-01     // 3FCC71C51D8E78AF
+		Lp5         = 1.818357216161805012e-01     // 3FC7466496CB03DE
+		Lp6         = 1.531383769920937332e-01     // 3FC39A09D078C69F
+		Lp7         = 1.479819860511658591e-01     // 3FC2F112DF3E5244
+	)
+
+	// special cases
+	// TODO(rsc): Remove manual inlining of IsNaN, IsInf
+	// when compiler does it for us
+	switch {
+	case x < -1 || x != x: // x < -1 || IsNaN(x): // includes -Inf
+		return NaN()
+	case x == -1:
+		return Inf(-1)
+	case x > MaxFloat64: // IsInf(x, 1):
+		return Inf(1)
+	}
+
+	absx := x
+	if absx < 0 {
+		absx = -absx
+	}
+
+	var f float64
+	var iu uint64
+	k := 1
+	if absx < Sqrt2M1 { //  |x| < Sqrt(2)-1
+		if absx < Small { // |x| < 2**-29
+			if absx < Tiny { // |x| < 2**-54
+				return x
+			}
+			return x - x*x*0.5
+		}
+		if x > Sqrt2HalfM1 { // Sqrt(2)/2-1 < x
+			// (Sqrt(2)/2-1) < x < (Sqrt(2)-1)
+			k = 0
+			f = x
+			iu = 1
+		}
+	}
+	var c float64
+	if k != 0 {
+		var u float64
+		if absx < Two53 { // 1<<53
+			u = 1.0 + x
+			iu = Float64bits(u)
+			k = int((iu >> 52) - 1023)
+			if k > 0 {
+				c = 1.0 - (u - x)
+			} else {
+				c = x - (u - 1.0) // correction term
+				c /= u
+			}
+		} else {
+			u = x
+			iu = Float64bits(u)
+			k = int((iu >> 52) - 1023)
+			c = 0
+		}
+		iu &= 0x000fffffffffffff
+		if iu < 0x0006a09e667f3bcd { // mantissa of Sqrt(2)
+			u = Float64frombits(iu | 0x3ff0000000000000) // normalize u
+		} else {
+			k += 1
+			u = Float64frombits(iu | 0x3fe0000000000000) // normalize u/2
+			iu = (0x0010000000000000 - iu) >> 2
+		}
+		f = u - 1.0 // Sqrt(2)/2 < u < Sqrt(2)
+	}
+	hfsq := 0.5 * f * f
+	var s, R, z float64
+	if iu == 0 { // |f| < 2**-20
+		if f == 0 {
+			if k == 0 {
+				return 0
+			} else {
+				c += float64(k) * Ln2Lo
+				return float64(k)*Ln2Hi + c
+			}
+		}
+		R = hfsq * (1.0 - 0.66666666666666666*f) // avoid division
+		if k == 0 {
+			return f - R
+		}
+		return float64(k)*Ln2Hi - ((R - (float64(k)*Ln2Lo + c)) - f)
+	}
+	s = f / (2.0 + f)
+	z = s * s
+	R = z * (Lp1 + z*(Lp2+z*(Lp3+z*(Lp4+z*(Lp5+z*(Lp6+z*Lp7))))))
+	if k == 0 {
+		return f - (hfsq - s*(hfsq+R))
+	}
+	return float64(k)*Ln2Hi - ((hfsq - (s*(hfsq+R) + (float64(k)*Ln2Lo + c))) - f)
+}