github.com/goshafaq/sonic@v0.0.0-20231026082336-871835fb94c6/internal/jit/assembler_amd64.go

/*
 * Copyright 2021 ByteDance Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package jit

import (
	"encoding/binary"
	"strconv"
	"strings"
	"sync"

	"github.com/goshafaq/sonic/internal/rt"
	"github.com/goshafaq/sonic/loader"
	"github.com/twitchyliquid64/golang-asm/obj"
	"github.com/twitchyliquid64/golang-asm/obj/x86"
)

const (
	_LB_jump_pc = "_jump_pc_"
)

type BaseAssembler struct {
	i        int
	f        func()
	c        []byte
	o        sync.Once
	pb       *Backend
	xrefs    map[string][]*obj.Prog
	labels   map[string]*obj.Prog
	pendings map[string][]*obj.Prog
}

/** Instruction Encoders **/

var _NOPS = [][16]byte{
	{0x90},                                                 // NOP
	{0x66, 0x90},                                           // 66 NOP
	{0x0f, 0x1f, 0x00},                                     // NOP DWORD ptr [EAX]
	{0x0f, 0x1f, 0x40, 0x00},                               // NOP DWORD ptr [EAX + 00H]
	{0x0f, 0x1f, 0x44, 0x00, 0x00},                         // NOP DWORD ptr [EAX + EAX*1 + 00H]
	{0x66, 0x0f, 0x1f, 0x44, 0x00, 0x00},                   // 66 NOP DWORD ptr [EAX + EAX*1 + 00H]
	{0x0f, 0x1f, 0x80, 0x00, 0x00, 0x00, 0x00},             // NOP DWORD ptr [EAX + 00000000H]
	{0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00},       // NOP DWORD ptr [EAX + EAX*1 + 00000000H]
	{0x66, 0x0f, 0x1f, 0x84, 0x00, 0x00, 0x00, 0x00, 0x00}, // 66 NOP DWORD ptr [EAX + EAX*1 + 00000000H]
}

func (self *BaseAssembler) NOP() *obj.Prog {
	p := self.pb.New()
	p.As = obj.ANOP
	self.pb.Append(p)
	return p
}

func (self *BaseAssembler) NOPn(n int) {
	for i := len(_NOPS); i > 0 && n > 0; i-- {
		for ; n >= i; n -= i {
			self.Byte(_NOPS[i-1][:i]...)
		}
	}
}

func (self *BaseAssembler) Byte(v ...byte) {
	for ; len(v) >= 8; v = v[8:] {
		self.From("QUAD", Imm(rt.Get64(v)))
	}
	for ; len(v) >= 4; v = v[4:] {
		self.From("LONG", Imm(int64(rt.Get32(v))))
	}
	for ; len(v) >= 2; v = v[2:] {
		self.From("WORD", Imm(int64(rt.Get16(v))))
	}
	for ; len(v) >= 1; v = v[1:] {
		self.From("BYTE", Imm(int64(v[0])))
	}
}

func (self *BaseAssembler) Mark(pc int) {
	self.i++
	self.Link(_LB_jump_pc + strconv.Itoa(pc))
}

func (self *BaseAssembler) Link(to string) {
	var p *obj.Prog
	var v []*obj.Prog

	/* placeholder substitution */
	if strings.Contains(to, "{n}") {
		to = strings.ReplaceAll(to, "{n}", strconv.Itoa(self.i))
	}

	/* check for duplications */
	if _, ok := self.labels[to]; ok {
		panic("label " + to + " has already been linked")
	}

	/* get the pending links */
	p = self.NOP()
	v = self.pendings[to]

	/* patch all the pending jumps */
	for _, q := range v {
		q.To.Val = p
	}

	/* mark the label as resolved */
	self.labels[to] = p
	delete(self.pendings, to)
}

func (self *BaseAssembler) Xref(pc int, d int64) {
	self.Sref(_LB_jump_pc+strconv.Itoa(pc), d)
}

func (self *BaseAssembler) Sref(to string, d int64) {
	p := self.pb.New()
	p.As = x86.ALONG
	p.From = Imm(-d)

	/* placeholder substitution */
	if strings.Contains(to, "{n}") {
		to = strings.ReplaceAll(to, "{n}", strconv.Itoa(self.i))
	}

	/* record the patch point */
	self.pb.Append(p)
	self.xrefs[to] = append(self.xrefs[to], p)
}

func (self *BaseAssembler) Xjmp(op string, to int) {
	self.Sjmp(op, _LB_jump_pc+strconv.Itoa(to))
}

func (self *BaseAssembler) Sjmp(op string, to string) {
	p := self.pb.New()
	p.As = As(op)

	/* placeholder substitution */
	if strings.Contains(to, "{n}") {
		to = strings.ReplaceAll(to, "{n}", strconv.Itoa(self.i))
	}

	/* check for backward jumps */
	if v, ok := self.labels[to]; ok {
		p.To.Val = v
	} else {
		self.pendings[to] = append(self.pendings[to], p)
	}

	/* mark as a branch, and add to instruction buffer */
	p.To.Type = obj.TYPE_BRANCH
	self.pb.Append(p)
}

func (self *BaseAssembler) Rjmp(op string, to obj.Addr) {
	p := self.pb.New()
	p.To = to
	p.As = As(op)
	self.pb.Append(p)
}

func (self *BaseAssembler) From(op string, val obj.Addr) {
	p := self.pb.New()
	p.As = As(op)
	p.From = val
	self.pb.Append(p)
}

func (self *BaseAssembler) Emit(op string, args ...obj.Addr) {
	p := self.pb.New()
	p.As = As(op)
	self.assignOperands(p, args)
	self.pb.Append(p)
}

func (self *BaseAssembler) assignOperands(p *obj.Prog, args []obj.Addr) {
	switch len(args) {
	case 0:
	case 1:
		p.To = args[0]
	case 2:
		p.To, p.From = args[1], args[0]
	case 3:
		p.To, p.From, p.RestArgs = args[2], args[0], args[1:2]
	case 4:
		p.To, p.From, p.RestArgs = args[2], args[3], args[:2]
	default:
		panic("invalid operands")
	}
}

/** Assembler Helpers **/

func (self *BaseAssembler) Size() int {
	self.build()
	return len(self.c)
}

func (self *BaseAssembler) Init(f func()) {
	self.i = 0
	self.f = f
	self.c = nil
	self.o = sync.Once{}
}

var jitLoader = loader.Loader{
	Name: "sonic.jit.",
	File: "github.com/goshafaq/sonic/jit.go",
	Options: loader.Options{
		NoPreempt: true,
	},
}

func (self *BaseAssembler) Load(name string, frameSize int, argSize int, argStackmap []bool, localStackmap []bool) loader.Function {
	self.build()
	return jitLoader.LoadOne(self.c, name, frameSize, argSize, argStackmap, localStackmap)
}

/** Assembler Stages **/

func (self *BaseAssembler) init() {
	self.pb = newBackend("amd64")
	self.xrefs = map[string][]*obj.Prog{}
	self.labels = map[string]*obj.Prog{}
	self.pendings = map[string][]*obj.Prog{}
}

func (self *BaseAssembler) build() {
	self.o.Do(func() {
		self.init()
		self.f()
		self.validate()
		self.assemble()
		self.resolve()
		self.release()
	})
}

func (self *BaseAssembler) release() {
	self.pb.Release()
	self.pb = nil
	self.xrefs = nil
	self.labels = nil
	self.pendings = nil
}

func (self *BaseAssembler) resolve() {
	for s, v := range self.xrefs {
		for _, prog := range v {
			if prog.As != x86.ALONG {
				panic("invalid RIP relative reference")
			} else if p, ok := self.labels[s]; !ok {
				panic("links are not fully resolved: " + s)
			} else {
				off := prog.From.Offset + p.Pc - prog.Pc
				binary.LittleEndian.PutUint32(self.c[prog.Pc:], uint32(off))
			}
		}
	}
}

func (self *BaseAssembler) validate() {
	for key := range self.pendings {
		panic("links are not fully resolved: " + key)
	}
}

func (self *BaseAssembler) assemble() {
	self.c = self.pb.Assemble()
}