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, 741 insertions, 0 deletions

diff --git a/libgo/go/big/int.go b/libgo/go/big/int.go
new file mode 100644
index 0000000..46e0087
--- /dev/null
+++ b/libgo/go/big/int.go
@@ -0,0 +1,741 @@
+// Copyright 2009 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.
+
+// This file implements signed multi-precision integers.
+
+package big
+
+import (
+	"fmt"
+	"rand"
+)
+
+// An Int represents a signed multi-precision integer.
+// The zero value for an Int represents the value 0.
+type Int struct {
+	neg bool // sign
+	abs nat  // absolute value of the integer
+}
+
+
+var intOne = &Int{false, natOne}
+
+
+// Sign returns:
+//
+//	-1 if x <  0
+//	 0 if x == 0
+//	+1 if x >  0
+//
+func (x *Int) Sign() int {
+	if len(x.abs) == 0 {
+		return 0
+	}
+	if x.neg {
+		return -1
+	}
+	return 1
+}
+
+
+// SetInt64 sets z to x and returns z.
+func (z *Int) SetInt64(x int64) *Int {
+	neg := false
+	if x < 0 {
+		neg = true
+		x = -x
+	}
+	z.abs = z.abs.setUint64(uint64(x))
+	z.neg = neg
+	return z
+}
+
+
+// NewInt allocates and returns a new Int set to x.
+func NewInt(x int64) *Int {
+	return new(Int).SetInt64(x)
+}
+
+
+// Set sets z to x and returns z.
+func (z *Int) Set(x *Int) *Int {
+	z.abs = z.abs.set(x.abs)
+	z.neg = x.neg
+	return z
+}
+
+
+// Abs sets z to |x| (the absolute value of x) and returns z.
+func (z *Int) Abs(x *Int) *Int {
+	z.abs = z.abs.set(x.abs)
+	z.neg = false
+	return z
+}
+
+
+// Neg sets z to -x and returns z.
+func (z *Int) Neg(x *Int) *Int {
+	z.abs = z.abs.set(x.abs)
+	z.neg = len(z.abs) > 0 && !x.neg // 0 has no sign
+	return z
+}
+
+
+// Add sets z to the sum x+y and returns z.
+func (z *Int) Add(x, y *Int) *Int {
+	neg := x.neg
+	if x.neg == y.neg {
+		// x + y == x + y
+		// (-x) + (-y) == -(x + y)
+		z.abs = z.abs.add(x.abs, y.abs)
+	} else {
+		// x + (-y) == x - y == -(y - x)
+		// (-x) + y == y - x == -(x - y)
+		if x.abs.cmp(y.abs) >= 0 {
+			z.abs = z.abs.sub(x.abs, y.abs)
+		} else {
+			neg = !neg
+			z.abs = z.abs.sub(y.abs, x.abs)
+		}
+	}
+	z.neg = len(z.abs) > 0 && neg // 0 has no sign
+	return z
+}
+
+
+// Sub sets z to the difference x-y and returns z.
+func (z *Int) Sub(x, y *Int) *Int {
+	neg := x.neg
+	if x.neg != y.neg {
+		// x - (-y) == x + y
+		// (-x) - y == -(x + y)
+		z.abs = z.abs.add(x.abs, y.abs)
+	} else {
+		// x - y == x - y == -(y - x)
+		// (-x) - (-y) == y - x == -(x - y)
+		if x.abs.cmp(y.abs) >= 0 {
+			z.abs = z.abs.sub(x.abs, y.abs)
+		} else {
+			neg = !neg
+			z.abs = z.abs.sub(y.abs, x.abs)
+		}
+	}
+	z.neg = len(z.abs) > 0 && neg // 0 has no sign
+	return z
+}
+
+
+// Mul sets z to the product x*y and returns z.
+func (z *Int) Mul(x, y *Int) *Int {
+	// x * y == x * y
+	// x * (-y) == -(x * y)
+	// (-x) * y == -(x * y)
+	// (-x) * (-y) == x * y
+	z.abs = z.abs.mul(x.abs, y.abs)
+	z.neg = len(z.abs) > 0 && x.neg != y.neg // 0 has no sign
+	return z
+}
+
+
+// MulRange sets z to the product of all integers
+// in the range [a, b] inclusively and returns z.
+// If a > b (empty range), the result is 1.
+func (z *Int) MulRange(a, b int64) *Int {
+	switch {
+	case a > b:
+		return z.SetInt64(1) // empty range
+	case a <= 0 && b >= 0:
+		return z.SetInt64(0) // range includes 0
+	}
+	// a <= b && (b < 0 || a > 0)
+
+	neg := false
+	if a < 0 {
+		neg = (b-a)&1 == 0
+		a, b = -b, -a
+	}
+
+	z.abs = z.abs.mulRange(uint64(a), uint64(b))
+	z.neg = neg
+	return z
+}
+
+
+// Binomial sets z to the binomial coefficient of (n, k) and returns z.
+func (z *Int) Binomial(n, k int64) *Int {
+	var a, b Int
+	a.MulRange(n-k+1, n)
+	b.MulRange(1, k)
+	return z.Quo(&a, &b)
+}
+
+
+// Quo sets z to the quotient x/y for y != 0 and returns z.
+// If y == 0, a division-by-zero run-time panic occurs.
+// See QuoRem for more details.
+func (z *Int) Quo(x, y *Int) *Int {
+	z.abs, _ = z.abs.div(nil, x.abs, y.abs)
+	z.neg = len(z.abs) > 0 && x.neg != y.neg // 0 has no sign
+	return z
+}
+
+
+// Rem sets z to the remainder x%y for y != 0 and returns z.
+// If y == 0, a division-by-zero run-time panic occurs.
+// See QuoRem for more details.
+func (z *Int) Rem(x, y *Int) *Int {
+	_, z.abs = nat(nil).div(z.abs, x.abs, y.abs)
+	z.neg = len(z.abs) > 0 && x.neg // 0 has no sign
+	return z
+}
+
+
+// QuoRem sets z to the quotient x/y and r to the remainder x%y
+// and returns the pair (z, r) for y != 0.
+// If y == 0, a division-by-zero run-time panic occurs.
+//
+// QuoRem implements T-division and modulus (like Go):
+//
+//	q = x/y      with the result truncated to zero
+//	r = x - y*q
+//
+// (See Daan Leijen, ``Division and Modulus for Computer Scientists''.)
+//
+func (z *Int) QuoRem(x, y, r *Int) (*Int, *Int) {
+	z.abs, r.abs = z.abs.div(r.abs, x.abs, y.abs)
+	z.neg, r.neg = len(z.abs) > 0 && x.neg != y.neg, len(r.abs) > 0 && x.neg // 0 has no sign
+	return z, r
+}
+
+
+// Div sets z to the quotient x/y for y != 0 and returns z.
+// If y == 0, a division-by-zero run-time panic occurs.
+// See DivMod for more details.
+func (z *Int) Div(x, y *Int) *Int {
+	y_neg := y.neg // z may be an alias for y
+	var r Int
+	z.QuoRem(x, y, &r)
+	if r.neg {
+		if y_neg {
+			z.Add(z, intOne)
+		} else {
+			z.Sub(z, intOne)
+		}
+	}
+	return z
+}
+
+
+// Mod sets z to the modulus x%y for y != 0 and returns z.
+// If y == 0, a division-by-zero run-time panic occurs.
+// See DivMod for more details.
+func (z *Int) Mod(x, y *Int) *Int {
+	y0 := y // save y
+	if z == y || alias(z.abs, y.abs) {
+		y0 = new(Int).Set(y)
+	}
+	var q Int
+	q.QuoRem(x, y, z)
+	if z.neg {
+		if y0.neg {
+			z.Sub(z, y0)
+		} else {
+			z.Add(z, y0)
+		}
+	}
+	return z
+}
+
+
+// DivMod sets z to the quotient x div y and m to the modulus x mod y
+// and returns the pair (z, m) for y != 0.
+// If y == 0, a division-by-zero run-time panic occurs.
+//
+// DivMod implements Euclidean division and modulus (unlike Go):
+//
+//	q = x div y  such that
+//	m = x - y*q  with 0 <= m < |q|
+//
+// (See Raymond T. Boute, ``The Euclidean definition of the functions
+// div and mod''. ACM Transactions on Programming Languages and
+// Systems (TOPLAS), 14(2):127-144, New York, NY, USA, 4/1992.
+// ACM press.)
+//
+func (z *Int) DivMod(x, y, m *Int) (*Int, *Int) {
+	y0 := y // save y
+	if z == y || alias(z.abs, y.abs) {
+		y0 = new(Int).Set(y)
+	}
+	z.QuoRem(x, y, m)
+	if m.neg {
+		if y0.neg {
+			z.Add(z, intOne)
+			m.Sub(m, y0)
+		} else {
+			z.Sub(z, intOne)
+			m.Add(m, y0)
+		}
+	}
+	return z, m
+}
+
+
+// Cmp compares x and y and returns:
+//
+//   -1 if x <  y
+//    0 if x == y
+//   +1 if x >  y
+//
+func (x *Int) Cmp(y *Int) (r int) {
+	// x cmp y == x cmp y
+	// x cmp (-y) == x
+	// (-x) cmp y == y
+	// (-x) cmp (-y) == -(x cmp y)
+	switch {
+	case x.neg == y.neg:
+		r = x.abs.cmp(y.abs)
+		if x.neg {
+			r = -r
+		}
+	case x.neg:
+		r = -1
+	default:
+		r = 1
+	}
+	return
+}
+
+
+func (x *Int) String() string {
+	s := ""
+	if x.neg {
+		s = "-"
+	}
+	return s + x.abs.string(10)
+}
+
+
+func fmtbase(ch int) int {
+	switch ch {
+	case 'b':
+		return 2
+	case 'o':
+		return 8
+	case 'd':
+		return 10
+	case 'x':
+		return 16
+	}
+	return 10
+}
+
+
+// Format is a support routine for fmt.Formatter. It accepts
+// the formats 'b' (binary), 'o' (octal), 'd' (decimal) and
+// 'x' (hexadecimal).
+//
+func (x *Int) Format(s fmt.State, ch int) {
+	if x.neg {
+		fmt.Fprint(s, "-")
+	}
+	fmt.Fprint(s, x.abs.string(fmtbase(ch)))
+}
+
+
+// Int64 returns the int64 representation of z.
+// If z cannot be represented in an int64, the result is undefined.
+func (x *Int) Int64() int64 {
+	if len(x.abs) == 0 {
+		return 0
+	}
+	v := int64(x.abs[0])
+	if _W == 32 && len(x.abs) > 1 {
+		v |= int64(x.abs[1]) << 32
+	}
+	if x.neg {
+		v = -v
+	}
+	return v
+}
+
+
+// SetString sets z to the value of s, interpreted in the given base,
+// and returns z and a boolean indicating success. If SetString fails,
+// the value of z is undefined.
+//
+// If the base argument is 0, the string prefix determines the actual
+// conversion base. A prefix of ``0x'' or ``0X'' selects base 16; the
+// ``0'' prefix selects base 8, and a ``0b'' or ``0B'' prefix selects
+// base 2. Otherwise the selected base is 10.
+//
+func (z *Int) SetString(s string, base int) (*Int, bool) {
+	if len(s) == 0 || base < 0 || base == 1 || 16 < base {
+		return z, false
+	}
+
+	neg := s[0] == '-'
+	if neg || s[0] == '+' {
+		s = s[1:]
+		if len(s) == 0 {
+			return z, false
+		}
+	}
+
+	var scanned int
+	z.abs, _, scanned = z.abs.scan(s, base)
+	if scanned != len(s) {
+		return z, false
+	}
+	z.neg = len(z.abs) > 0 && neg // 0 has no sign
+
+	return z, true
+}
+
+
+// SetBytes interprets b as the bytes of a big-endian, unsigned integer and
+// sets z to that value.
+func (z *Int) SetBytes(b []byte) *Int {
+	const s = _S
+	z.abs = z.abs.make((len(b) + s - 1) / s)
+
+	j := 0
+	for len(b) >= s {
+		var w Word
+
+		for i := s; i > 0; i-- {
+			w <<= 8
+			w |= Word(b[len(b)-i])
+		}
+
+		z.abs[j] = w
+		j++
+		b = b[0 : len(b)-s]
+	}
+
+	if len(b) > 0 {
+		var w Word
+
+		for i := len(b); i > 0; i-- {
+			w <<= 8
+			w |= Word(b[len(b)-i])
+		}
+
+		z.abs[j] = w
+	}
+
+	z.abs = z.abs.norm()
+	z.neg = false
+	return z
+}
+
+
+// Bytes returns the absolute value of x as a big-endian byte array.
+func (z *Int) Bytes() []byte {
+	const s = _S
+	b := make([]byte, len(z.abs)*s)
+
+	for i, w := range z.abs {
+		wordBytes := b[(len(z.abs)-i-1)*s : (len(z.abs)-i)*s]
+		for j := s - 1; j >= 0; j-- {
+			wordBytes[j] = byte(w)
+			w >>= 8
+		}
+	}
+
+	i := 0
+	for i < len(b) && b[i] == 0 {
+		i++
+	}
+
+	return b[i:]
+}
+
+
+// BitLen returns the length of the absolute value of z in bits.
+// The bit length of 0 is 0.
+func (z *Int) BitLen() int {
+	return z.abs.bitLen()
+}
+
+
+// Exp sets z = x**y mod m. If m is nil, z = x**y.
+// See Knuth, volume 2, section 4.6.3.
+func (z *Int) Exp(x, y, m *Int) *Int {
+	if y.neg || len(y.abs) == 0 {
+		neg := x.neg
+		z.SetInt64(1)
+		z.neg = neg
+		return z
+	}
+
+	var mWords nat
+	if m != nil {
+		mWords = m.abs
+	}
+
+	z.abs = z.abs.expNN(x.abs, y.abs, mWords)
+	z.neg = len(z.abs) > 0 && x.neg && y.abs[0]&1 == 1 // 0 has no sign
+	return z
+}
+
+
+// GcdInt sets d to the greatest common divisor of a and b, which must be
+// positive numbers.
+// If x and y are not nil, GcdInt sets x and y such that d = a*x + b*y.
+// If either a or b is not positive, GcdInt sets d = x = y = 0.
+func GcdInt(d, x, y, a, b *Int) {
+	if a.neg || b.neg {
+		d.SetInt64(0)
+		if x != nil {
+			x.SetInt64(0)
+		}
+		if y != nil {
+			y.SetInt64(0)
+		}
+		return
+	}
+
+	A := new(Int).Set(a)
+	B := new(Int).Set(b)
+
+	X := new(Int)
+	Y := new(Int).SetInt64(1)
+
+	lastX := new(Int).SetInt64(1)
+	lastY := new(Int)
+
+	q := new(Int)
+	temp := new(Int)
+
+	for len(B.abs) > 0 {
+		r := new(Int)
+		q, r = q.QuoRem(A, B, r)
+
+		A, B = B, r
+
+		temp.Set(X)
+		X.Mul(X, q)
+		X.neg = !X.neg
+		X.Add(X, lastX)
+		lastX.Set(temp)
+
+		temp.Set(Y)
+		Y.Mul(Y, q)
+		Y.neg = !Y.neg
+		Y.Add(Y, lastY)
+		lastY.Set(temp)
+	}
+
+	if x != nil {
+		*x = *lastX
+	}
+
+	if y != nil {
+		*y = *lastY
+	}
+
+	*d = *A
+}
+
+
+// ProbablyPrime performs n Miller-Rabin tests to check whether z is prime.
+// If it returns true, z is prime with probability 1 - 1/4^n.
+// If it returns false, z is not prime.
+func ProbablyPrime(z *Int, n int) bool {
+	return !z.neg && z.abs.probablyPrime(n)
+}
+
+
+// Rand sets z to a pseudo-random number in [0, n) and returns z. 
+func (z *Int) Rand(rnd *rand.Rand, n *Int) *Int {
+	z.neg = false
+	if n.neg == true || len(n.abs) == 0 {
+		z.abs = nil
+		return z
+	}
+	z.abs = z.abs.random(rnd, n.abs, n.abs.bitLen())
+	return z
+}
+
+
+// ModInverse sets z to the multiplicative inverse of g in the group ℤ/pℤ (where
+// p is a prime) and returns z.
+func (z *Int) ModInverse(g, p *Int) *Int {
+	var d Int
+	GcdInt(&d, z, nil, g, p)
+	// x and y are such that g*x + p*y = d. Since p is prime, d = 1. Taking
+	// that modulo p results in g*x = 1, therefore x is the inverse element.
+	if z.neg {
+		z.Add(z, p)
+	}
+	return z
+}
+
+
+// Lsh sets z = x << n and returns z.
+func (z *Int) Lsh(x *Int, n uint) *Int {
+	z.abs = z.abs.shl(x.abs, n)
+	z.neg = x.neg
+	return z
+}
+
+
+// Rsh sets z = x >> n and returns z.
+func (z *Int) Rsh(x *Int, n uint) *Int {
+	if x.neg {
+		// (-x) >> s == ^(x-1) >> s == ^((x-1) >> s) == -(((x-1) >> s) + 1)
+		t := z.abs.sub(x.abs, natOne) // no underflow because |x| > 0
+		t = t.shr(t, n)
+		z.abs = t.add(t, natOne)
+		z.neg = true // z cannot be zero if x is negative
+		return z
+	}
+
+	z.abs = z.abs.shr(x.abs, n)
+	z.neg = false
+	return z
+}
+
+
+// And sets z = x & y and returns z.
+func (z *Int) And(x, y *Int) *Int {
+	if x.neg == y.neg {
+		if x.neg {
+			// (-x) & (-y) == ^(x-1) & ^(y-1) == ^((x-1) | (y-1)) == -(((x-1) | (y-1)) + 1)
+			x1 := nat{}.sub(x.abs, natOne)
+			y1 := nat{}.sub(y.abs, natOne)
+			z.abs = z.abs.add(z.abs.or(x1, y1), natOne)
+			z.neg = true // z cannot be zero if x and y are negative
+			return z
+		}
+
+		// x & y == x & y
+		z.abs = z.abs.and(x.abs, y.abs)
+		z.neg = false
+		return z
+	}
+
+	// x.neg != y.neg
+	if x.neg {
+		x, y = y, x // & is symmetric
+	}
+
+	// x & (-y) == x & ^(y-1) == x &^ (y-1)
+	y1 := nat{}.sub(y.abs, natOne)
+	z.abs = z.abs.andNot(x.abs, y1)
+	z.neg = false
+	return z
+}
+
+
+// AndNot sets z = x &^ y and returns z.
+func (z *Int) AndNot(x, y *Int) *Int {
+	if x.neg == y.neg {
+		if x.neg {
+			// (-x) &^ (-y) == ^(x-1) &^ ^(y-1) == ^(x-1) & (y-1) == (y-1) &^ (x-1)
+			x1 := nat{}.sub(x.abs, natOne)
+			y1 := nat{}.sub(y.abs, natOne)
+			z.abs = z.abs.andNot(y1, x1)
+			z.neg = false
+			return z
+		}
+
+		// x &^ y == x &^ y
+		z.abs = z.abs.andNot(x.abs, y.abs)
+		z.neg = false
+		return z
+	}
+
+	if x.neg {
+		// (-x) &^ y == ^(x-1) &^ y == ^(x-1) & ^y == ^((x-1) | y) == -(((x-1) | y) + 1)
+		x1 := nat{}.sub(x.abs, natOne)
+		z.abs = z.abs.add(z.abs.or(x1, y.abs), natOne)
+		z.neg = true // z cannot be zero if x is negative and y is positive
+		return z
+	}
+
+	// x &^ (-y) == x &^ ^(y-1) == x & (y-1)
+	y1 := nat{}.add(y.abs, natOne)
+	z.abs = z.abs.and(x.abs, y1)
+	z.neg = false
+	return z
+}
+
+
+// Or sets z = x | y and returns z.
+func (z *Int) Or(x, y *Int) *Int {
+	if x.neg == y.neg {
+		if x.neg {
+			// (-x) | (-y) == ^(x-1) | ^(y-1) == ^((x-1) & (y-1)) == -(((x-1) & (y-1)) + 1)
+			x1 := nat{}.sub(x.abs, natOne)
+			y1 := nat{}.sub(y.abs, natOne)
+			z.abs = z.abs.add(z.abs.and(x1, y1), natOne)
+			z.neg = true // z cannot be zero if x and y are negative
+			return z
+		}
+
+		// x | y == x | y
+		z.abs = z.abs.or(x.abs, y.abs)
+		z.neg = false
+		return z
+	}
+
+	// x.neg != y.neg
+	if x.neg {
+		x, y = y, x // | is symmetric
+	}
+
+	// x | (-y) == x | ^(y-1) == ^((y-1) &^ x) == -(^((y-1) &^ x) + 1)
+	y1 := nat{}.sub(y.abs, natOne)
+	z.abs = z.abs.add(z.abs.andNot(y1, x.abs), natOne)
+	z.neg = true // z cannot be zero if one of x or y is negative
+	return z
+}
+
+
+// Xor sets z = x ^ y and returns z.
+func (z *Int) Xor(x, y *Int) *Int {
+	if x.neg == y.neg {
+		if x.neg {
+			// (-x) ^ (-y) == ^(x-1) ^ ^(y-1) == (x-1) ^ (y-1)
+			x1 := nat{}.sub(x.abs, natOne)
+			y1 := nat{}.sub(y.abs, natOne)
+			z.abs = z.abs.xor(x1, y1)
+			z.neg = false
+			return z
+		}
+
+		// x ^ y == x ^ y
+		z.abs = z.abs.xor(x.abs, y.abs)
+		z.neg = false
+		return z
+	}
+
+	// x.neg != y.neg
+	if x.neg {
+		x, y = y, x // ^ is symmetric
+	}
+
+	// x ^ (-y) == x ^ ^(y-1) == ^(x ^ (y-1)) == -((x ^ (y-1)) + 1)
+	y1 := nat{}.sub(y.abs, natOne)
+	z.abs = z.abs.add(z.abs.xor(x.abs, y1), natOne)
+	z.neg = true // z cannot be zero if only one of x or y is negative
+	return z
+}
+
+
+// Not sets z = ^x and returns z.
+func (z *Int) Not(x *Int) *Int {
+	if x.neg {
+		// ^(-x) == ^(^(x-1)) == x-1
+		z.abs = z.abs.sub(x.abs, natOne)
+		z.neg = false
+		return z
+	}
+
+	// ^x == -x-1 == -(x+1)
+	z.abs = z.abs.add(x.abs, natOne)
+	z.neg = true // z cannot be zero if x is positive
+	return z
+}