cmd/evm, core/asm: add EVM assembler (#3686)

The evm compile command implements a simple assembly language that compiles to
EVM bytecode.

cmd/evm/compiler.go

@@ -0,0 +1,55 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of go-ethereum.
+//
+// go-ethereum is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// go-ethereum is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"errors"
+	"fmt"
+	"io/ioutil"
+
+	"github.com/ethereum/go-ethereum/cmd/evm/internal/compiler"
+
+	cli "gopkg.in/urfave/cli.v1"
+)
+
+var compileCommand = cli.Command{
+	Action:    compileCmd,
+	Name:      "compile",
+	Usage:     "compiles easm source to evm binary",
+	ArgsUsage: "<file>",
+}
+
+func compileCmd(ctx *cli.Context) error {
+	debug := ctx.GlobalBool(DebugFlag.Name)
+
+	if len(ctx.Args().First()) == 0 {
+		return errors.New("filename required")
+	}
+
+	fn := ctx.Args().First()
+	src, err := ioutil.ReadFile(fn)
+	if err != nil {
+		return err
+	}
+
+	bin, err := compiler.Compile(fn, src, debug)
+	if err != nil {
+		return err
+	}
+	fmt.Println(bin)
+	return nil
+}