1 files changed, 99 insertions, 0 deletions
diff --git a/src/cmd/compile/internal/ir/const.go b/src/cmd/compile/internal/ir/const.go
new file mode 100644
index 0000000..f0b6695
--- /dev/null
+++ b/src/cmd/compile/internal/ir/const.go
@@ -0,0 +1,99 @@
+// 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 ir
+
+import (
+	"go/constant"
+	"math"
+	"math/big"
+
+	"cmd/compile/internal/base"
+	"cmd/compile/internal/types"
+)
+
+func NewBool(b bool) Node {
+	return NewLiteral(constant.MakeBool(b))
+}
+
+func NewInt(v int64) Node {
+	return NewLiteral(constant.MakeInt64(v))
+}
+
+func NewString(s string) Node {
+	return NewLiteral(constant.MakeString(s))
+}
+
+const (
+	// Maximum size in bits for big.Ints before signaling
+	// overflow and also mantissa precision for big.Floats.
+	ConstPrec = 512
+)
+
+func BigFloat(v constant.Value) *big.Float {
+	f := new(big.Float)
+	f.SetPrec(ConstPrec)
+	switch u := constant.Val(v).(type) {
+	case int64:
+		f.SetInt64(u)
+	case *big.Int:
+		f.SetInt(u)
+	case *big.Float:
+		f.Set(u)
+	case *big.Rat:
+		f.SetRat(u)
+	default:
+		base.Fatalf("unexpected: %v", u)
+	}
+	return f
+}
+
+// ConstOverflow reports whether constant value v is too large
+// to represent with type t.
+func ConstOverflow(v constant.Value, t *types.Type) bool {
+	switch {
+	case t.IsInteger():
+		bits := uint(8 * t.Size())
+		if t.IsUnsigned() {
+			x, ok := constant.Uint64Val(v)
+			return !ok || x>>bits != 0
+		}
+		x, ok := constant.Int64Val(v)
+		if x < 0 {
+			x = ^x
+		}
+		return !ok || x>>(bits-1) != 0
+	case t.IsFloat():
+		switch t.Size() {
+		case 4:
+			f, _ := constant.Float32Val(v)
+			return math.IsInf(float64(f), 0)
+		case 8:
+			f, _ := constant.Float64Val(v)
+			return math.IsInf(f, 0)
+		}
+	case t.IsComplex():
+		ft := types.FloatForComplex(t)
+		return ConstOverflow(constant.Real(v), ft) || ConstOverflow(constant.Imag(v), ft)
+	}
+	base.Fatalf("ConstOverflow: %v, %v", v, t)
+	panic("unreachable")
+}
+
+// IsConstNode reports whether n is a Go language constant (as opposed to a
+// compile-time constant).
+//
+// Expressions derived from nil, like string([]byte(nil)), while they
+// may be known at compile time, are not Go language constants.
+func IsConstNode(n Node) bool {
+	return n.Op() == OLITERAL
+}
+
+func IsSmallIntConst(n Node) bool {
+	if n.Op() == OLITERAL {
+		v, ok := constant.Int64Val(n.Val())
+		return ok && int64(int32(v)) == v
+	}
+	return false
+}