475a241446
Intended to address an asmdecl error. [amd64] Butterfly: use of unnamed argument 0(FP); offset 0 is x0+0(FP) Updates #24
201 lines
6.1 KiB
Markdown
201 lines
6.1 KiB
Markdown
<p align="center">
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<img src="logo.svg" width="40%" border="0" alt="avo" />
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<br />
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<a href="https://travis-ci.org/mmcloughlin/avo"><img src="https://img.shields.io/travis/mmcloughlin/avo.svg?style=flat-square" alt="Build Status" /></a>
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<a href="http://godoc.org/github.com/mmcloughlin/avo"><img src="http://img.shields.io/badge/godoc-reference-5272B4.svg?style=flat-square" alt="GoDoc" /></a>
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</p>
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<p align="center">Generate x86 Assembly with Go</p>
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`avo` makes high-performance Go assembly easier to write, review and maintain. The `avo` package presents a familiar assembly-like interface that simplifies development without sacrificing performance:
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* **Use Go control structures** for assembly generation; `avo` programs _are_ Go programs
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* **Register allocation**: write functions with virtual registers and `avo` assigns physical registers for you
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* **Automatically load arguments and store return values**: ensure memory offsets are correct for complex structures
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* **Generation of stub files** to interface with your Go package
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_Note: APIs subject to change while `avo` is still in an experimental phase. You can use it to build [real things](examples) but we suggest you pin a version with your package manager of choice._
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## Quick Start
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Install `avo` with `go get`:
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```
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$ go get -u github.com/mmcloughlin/avo
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```
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`avo` assembly generators are pure Go programs. Here's a function that adds two `uint64` values:
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[embedmd]:# (examples/add/asm.go)
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```go
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// +build ignore
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package main
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import (
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. "github.com/mmcloughlin/avo/build"
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)
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func main() {
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TEXT("Add", NOSPLIT, "func(x, y uint64) uint64")
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Doc("Add adds x and y.")
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x := Load(Param("x"), GP64())
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y := Load(Param("y"), GP64())
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ADDQ(x, y)
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Store(y, ReturnIndex(0))
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RET()
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Generate()
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}
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```
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`go run` this code to see the assembly output. To integrate this into the rest of your Go package we recommend a [`go:generate`](https://blog.golang.org/generate) line to produce the assembly and the corresponding Go stub file.
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[embedmd]:# (examples/add/add_test.go go /.*go:generate.*/)
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```go
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//go:generate go run asm.go -out add.s -stubs stub.go
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```
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After running `go generate` the [`add.s`](examples/add/add.s) file will contain the Go assembly.
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[embedmd]:# (examples/add/add.s)
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```s
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// Code generated by command: go run asm.go -out add.s -stubs stub.go. DO NOT EDIT.
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#include "textflag.h"
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// func Add(x uint64, y uint64) uint64
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TEXT ·Add(SB), NOSPLIT, $0-24
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MOVQ x+0(FP), AX
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MOVQ y+8(FP), CX
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ADDQ AX, CX
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MOVQ CX, ret+16(FP)
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RET
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```
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The same call will produce the stub file [`stub.go`](examples/add/stub.go) which will enable the function to be called from your Go code.
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[embedmd]:# (examples/add/stub.go)
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```go
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// Code generated by command: go run asm.go -out add.s -stubs stub.go. DO NOT EDIT.
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package add
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// Add adds x and y.
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func Add(x uint64, y uint64) uint64
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```
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See the [`examples/add`](examples/add) directory for the complete working example.
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## Examples
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See [`examples`](examples) for the full suite of examples.
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### Slice Sum
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Sum a slice of `uint64`s:
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[embedmd]:# (examples/sum/asm.go /func main/ /^}/)
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```go
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func main() {
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TEXT("Sum", NOSPLIT, "func(xs []uint64) uint64")
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Doc("Sum returns the sum of the elements in xs.")
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ptr := Load(Param("xs").Base(), GP64())
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n := Load(Param("xs").Len(), GP64())
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Comment("Initialize sum register to zero.")
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s := GP64()
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XORQ(s, s)
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Label("loop")
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Comment("Loop until zero bytes remain.")
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CMPQ(n, Imm(0))
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JE(LabelRef("done"))
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Comment("Load from pointer and add to running sum.")
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ADDQ(Mem{Base: ptr}, s)
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Comment("Advance pointer, decrement byte count.")
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ADDQ(Imm(8), ptr)
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DECQ(n)
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JMP(LabelRef("loop"))
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Label("done")
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Comment("Store sum to return value.")
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Store(s, ReturnIndex(0))
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RET()
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Generate()
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}
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```
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The result from this code generator is:
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[embedmd]:# (examples/sum/sum.s)
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```s
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// Code generated by command: go run asm.go -out sum.s -stubs stub.go. DO NOT EDIT.
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#include "textflag.h"
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// func Sum(xs []uint64) uint64
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TEXT ·Sum(SB), NOSPLIT, $0-32
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MOVQ xs_base+0(FP), AX
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MOVQ xs_len+8(FP), CX
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// Initialize sum register to zero.
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XORQ DX, DX
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loop:
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// Loop until zero bytes remain.
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CMPQ CX, $0x00
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JE done
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// Load from pointer and add to running sum.
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ADDQ (AX), DX
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// Advance pointer, decrement byte count.
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ADDQ $0x08, AX
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DECQ CX
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JMP loop
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done:
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// Store sum to return value.
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MOVQ DX, ret+24(FP)
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RET
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```
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Full example at [`examples/sum`](examples/sum).
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### Features
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For demonstrations of `avo` features:
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* **[args](examples/args):** Loading function arguments.
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* **[returns](examples/returns):** Building return values.
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* **[data](examples/data):** Defining `DATA` sections.
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* **[complex](examples/complex):** Working with `complex{64,128}` types.
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### Real Examples
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Implementations of full algorithms:
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* **[sha1](examples/sha1):** [SHA-1](https://en.wikipedia.org/wiki/SHA-1) cryptographic hash.
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* **[fnv1a](examples/fnv1a):** [FNV-1a](https://en.wikipedia.org/wiki/Fowler%E2%80%93Noll%E2%80%93Vo_hash_function#FNV-1a_hash) hash function.
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* **[dot](examples/dot):** Vector dot product.
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* **[geohash](examples/geohash):** Integer [geohash](https://en.wikipedia.org/wiki/Geohash) encoding.
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* **[stadtx](examples/stadtx):** [`StadtX` hash](https://github.com/demerphq/BeagleHash) port from [dgryski/go-stadtx](https://github.com/dgryski/go-stadtx).
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## Contributing
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Contributions to `avo` are welcome:
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* Feedback from using `avo` in a real project is incredibly valuable. Consider [porting an existing project to `avo`](https://github.com/mmcloughlin/avo/issues/40).
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* [Submit bug reports](https://github.com/mmcloughlin/avo/issues/new) to the issues page.
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* Pull requests accepted. Take a look at outstanding [issues](https://github.com/mmcloughlin/avo/issues) for ideas (especially the ["good first issue"](https://github.com/mmcloughlin/avo/labels/good%20first%20issue) label).
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## Credits
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Inspired by the [PeachPy](https://github.com/Maratyszcza/PeachPy) and [asmjit](https://github.com/asmjit/asmjit) projects. Thanks to [Damian Gryski](https://github.com/dgryski) for advice, and his [extensive library of PeachPy Go projects](https://github.com/mmcloughlin/avo/issues/40).
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## License
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`avo` is available under the [BSD 3-Clause License](LICENSE).
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