README
¶
gojit -- pure-golang runtime code-generation
This is the result of my spending the hack day at Gophercon 2014 playing with doing JIT from golang code. This repository contains several packages:
-
gojitContains the basic JIT support -- allocate executable chunks of memory, and convert them into callable golang functions.
-
amd64Contains a simplistic amd64 assembler designed for use with
gojit -
bfContains a just-in-time compiler for Brainfuck that demos the above packages
-
gobfContains a binary that provides a command-line interface to
bf
Using
gobf can be fetched using
go get github.com/nelhage/gojit/gobf
And then run as gobf file.bf. For some built-in examples:
$ gobf $GOPATH/src/github.com/nelhage/gojit/bf/test/hello.bf
Hello World!
$ gobf $GOPATH/src/github.com/nelhage/gojit/bf/test/hello.bf | gobf $GOPATH/src/github.com/nelhage/gojit/bf/test/rot13.bf
Uryyb Jbeyq!
Portability
This code has been tested on darwin/amd64 and linux/amd64. It is
extremely unlikely to work anywhere else.
Documentation
¶
Overview ¶
Package gojit contains basic support for writing JITs in golang. It contains functions for allocating byte slices in executable memory, and converting between such slices and golang function types.
Index ¶
Constants ¶
const PageSize = 4096
PageSize is the size of a memory page. The len argument to Alloc should be an integer multiple of the page size.
Variables ¶
This section is empty.
Functions ¶
func Alloc ¶
Alloc returns a byte slice of the specified length that is marked RWX -- i.e. the memory in it can be both written and executed. This is just a simple wrapper around syscall.Mmap.
len most likely needs to be a multiple of PageSize.
func Build ¶
func Build(b []byte) func()
Build returns a nullary golang function that will result in jumping into the specified byte slice. The slice should in most cases be a slice returned by Alloc, although you could also use syscall.Mmap or syscall.Mprotect directly.
func BuildTo ¶
func BuildTo(b []byte, out interface{})
BuildTo converts a byte-slice into an arbitrary-signatured function. The out argument should be a pointer to a variable of `func' type.
Arguments to the resulting function will be passed to code using a hybrid of the GCC and 6c ABIs: The compiled code will receive, via the GCC ABI, a single argument, a void* pointing at the beginning of the 6c argument frame. For concreteness, on amd64, a func([]byte) int would result in %rdi pointing at the 6c stack frame, like so:
24(%rdi) [ return value ] 16(%rdi) [ cap(slice) ] 8(%rdi) [ len(slice) ] 0(%rdi) [ uint8* data ]
Types ¶
Source Files
Directories
¶
| Path | Synopsis |
|---|---|
|
Package amd64 implements a simple amd64 assembler.
|
Package amd64 implements a simple amd64 assembler. |
|
Package bf implements a JIT compiler for the Brainfuck programming language.
|
Package bf implements a JIT compiler for the Brainfuck programming language. |