1 files changed, 304 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/gc/mpint.go b/src/cmd/compile/internal/gc/mpint.go
new file mode 100644
index 0000000..340350b
--- /dev/null
+++ b/src/cmd/compile/internal/gc/mpint.go
@@ -0,0 +1,304 @@
+// 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.
+
+package gc
+
+import (
+	"fmt"
+	"math/big"
+)
+
+// implements integer arithmetic
+
+// Mpint represents an integer constant.
+type Mpint struct {
+	Val  big.Int
+	Ovf  bool // set if Val overflowed compiler limit (sticky)
+	Rune bool // set if syntax indicates default type rune
+}
+
+func (a *Mpint) SetOverflow() {
+	a.Val.SetUint64(1) // avoid spurious div-zero errors
+	a.Ovf = true
+}
+
+func (a *Mpint) checkOverflow(extra int) bool {
+	// We don't need to be precise here, any reasonable upper limit would do.
+	// For now, use existing limit so we pass all the tests unchanged.
+	if a.Val.BitLen()+extra > Mpprec {
+		a.SetOverflow()
+	}
+	return a.Ovf
+}
+
+func (a *Mpint) Set(b *Mpint) {
+	a.Val.Set(&b.Val)
+}
+
+func (a *Mpint) SetFloat(b *Mpflt) bool {
+	// avoid converting huge floating-point numbers to integers
+	// (2*Mpprec is large enough to permit all tests to pass)
+	if b.Val.MantExp(nil) > 2*Mpprec {
+		a.SetOverflow()
+		return false
+	}
+
+	if _, acc := b.Val.Int(&a.Val); acc == big.Exact {
+		return true
+	}
+
+	const delta = 16 // a reasonably small number of bits > 0
+	var t big.Float
+	t.SetPrec(Mpprec - delta)
+
+	// try rounding down a little
+	t.SetMode(big.ToZero)
+	t.Set(&b.Val)
+	if _, acc := t.Int(&a.Val); acc == big.Exact {
+		return true
+	}
+
+	// try rounding up a little
+	t.SetMode(big.AwayFromZero)
+	t.Set(&b.Val)
+	if _, acc := t.Int(&a.Val); acc == big.Exact {
+		return true
+	}
+
+	a.Ovf = false
+	return false
+}
+
+func (a *Mpint) Add(b *Mpint) {
+	if a.Ovf || b.Ovf {
+		if nsavederrors+nerrors == 0 {
+			Fatalf("ovf in Mpint Add")
+		}
+		a.SetOverflow()
+		return
+	}
+
+	a.Val.Add(&a.Val, &b.Val)
+
+	if a.checkOverflow(0) {
+		yyerror("constant addition overflow")
+	}
+}
+
+func (a *Mpint) Sub(b *Mpint) {
+	if a.Ovf || b.Ovf {
+		if nsavederrors+nerrors == 0 {
+			Fatalf("ovf in Mpint Sub")
+		}
+		a.SetOverflow()
+		return
+	}
+
+	a.Val.Sub(&a.Val, &b.Val)
+
+	if a.checkOverflow(0) {
+		yyerror("constant subtraction overflow")
+	}
+}
+
+func (a *Mpint) Mul(b *Mpint) {
+	if a.Ovf || b.Ovf {
+		if nsavederrors+nerrors == 0 {
+			Fatalf("ovf in Mpint Mul")
+		}
+		a.SetOverflow()
+		return
+	}
+
+	a.Val.Mul(&a.Val, &b.Val)
+
+	if a.checkOverflow(0) {
+		yyerror("constant multiplication overflow")
+	}
+}
+
+func (a *Mpint) Quo(b *Mpint) {
+	if a.Ovf || b.Ovf {
+		if nsavederrors+nerrors == 0 {
+			Fatalf("ovf in Mpint Quo")
+		}
+		a.SetOverflow()
+		return
+	}
+
+	a.Val.Quo(&a.Val, &b.Val)
+
+	if a.checkOverflow(0) {
+		// can only happen for div-0 which should be checked elsewhere
+		yyerror("constant division overflow")
+	}
+}
+
+func (a *Mpint) Rem(b *Mpint) {
+	if a.Ovf || b.Ovf {
+		if nsavederrors+nerrors == 0 {
+			Fatalf("ovf in Mpint Rem")
+		}
+		a.SetOverflow()
+		return
+	}
+
+	a.Val.Rem(&a.Val, &b.Val)
+
+	if a.checkOverflow(0) {
+		// should never happen
+		yyerror("constant modulo overflow")
+	}
+}
+
+func (a *Mpint) Or(b *Mpint) {
+	if a.Ovf || b.Ovf {
+		if nsavederrors+nerrors == 0 {
+			Fatalf("ovf in Mpint Or")
+		}
+		a.SetOverflow()
+		return
+	}
+
+	a.Val.Or(&a.Val, &b.Val)
+}
+
+func (a *Mpint) And(b *Mpint) {
+	if a.Ovf || b.Ovf {
+		if nsavederrors+nerrors == 0 {
+			Fatalf("ovf in Mpint And")
+		}
+		a.SetOverflow()
+		return
+	}
+
+	a.Val.And(&a.Val, &b.Val)
+}
+
+func (a *Mpint) AndNot(b *Mpint) {
+	if a.Ovf || b.Ovf {
+		if nsavederrors+nerrors == 0 {
+			Fatalf("ovf in Mpint AndNot")
+		}
+		a.SetOverflow()
+		return
+	}
+
+	a.Val.AndNot(&a.Val, &b.Val)
+}
+
+func (a *Mpint) Xor(b *Mpint) {
+	if a.Ovf || b.Ovf {
+		if nsavederrors+nerrors == 0 {
+			Fatalf("ovf in Mpint Xor")
+		}
+		a.SetOverflow()
+		return
+	}
+
+	a.Val.Xor(&a.Val, &b.Val)
+}
+
+func (a *Mpint) Lsh(b *Mpint) {
+	if a.Ovf || b.Ovf {
+		if nsavederrors+nerrors == 0 {
+			Fatalf("ovf in Mpint Lsh")
+		}
+		a.SetOverflow()
+		return
+	}
+
+	s := b.Int64()
+	if s < 0 || s >= Mpprec {
+		msg := "shift count too large"
+		if s < 0 {
+			msg = "invalid negative shift count"
+		}
+		yyerror("%s: %d", msg, s)
+		a.SetInt64(0)
+		return
+	}
+
+	if a.checkOverflow(int(s)) {
+		yyerror("constant shift overflow")
+		return
+	}
+	a.Val.Lsh(&a.Val, uint(s))
+}
+
+func (a *Mpint) Rsh(b *Mpint) {
+	if a.Ovf || b.Ovf {
+		if nsavederrors+nerrors == 0 {
+			Fatalf("ovf in Mpint Rsh")
+		}
+		a.SetOverflow()
+		return
+	}
+
+	s := b.Int64()
+	if s < 0 {
+		yyerror("invalid negative shift count: %d", s)
+		if a.Val.Sign() < 0 {
+			a.SetInt64(-1)
+		} else {
+			a.SetInt64(0)
+		}
+		return
+	}
+
+	a.Val.Rsh(&a.Val, uint(s))
+}
+
+func (a *Mpint) Cmp(b *Mpint) int {
+	return a.Val.Cmp(&b.Val)
+}
+
+func (a *Mpint) CmpInt64(c int64) int {
+	if c == 0 {
+		return a.Val.Sign() // common case shortcut
+	}
+	return a.Val.Cmp(big.NewInt(c))
+}
+
+func (a *Mpint) Neg() {
+	a.Val.Neg(&a.Val)
+}
+
+func (a *Mpint) Int64() int64 {
+	if a.Ovf {
+		if nsavederrors+nerrors == 0 {
+			Fatalf("constant overflow")
+		}
+		return 0
+	}
+
+	return a.Val.Int64()
+}
+
+func (a *Mpint) SetInt64(c int64) {
+	a.Val.SetInt64(c)
+}
+
+func (a *Mpint) SetString(as string) {
+	_, ok := a.Val.SetString(as, 0)
+	if !ok {
+		// The lexer checks for correct syntax of the literal
+		// and reports detailed errors. Thus SetString should
+		// never fail (in theory it might run out of memory,
+		// but that wouldn't be reported as an error here).
+		Fatalf("malformed integer constant: %s", as)
+		return
+	}
+	if a.checkOverflow(0) {
+		yyerror("constant too large: %s", as)
+	}
+}
+
+func (a *Mpint) GoString() string {
+	return a.Val.String()
+}
+
+func (a *Mpint) String() string {
+	return fmt.Sprintf("%#x", &a.Val)
+}