compiler.go

/*
 * Copyright 2022 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 encoder

import (
    `fmt`
    `reflect`
    `strings`

    `github.com/cloudwego/frugal/internal/binary/defs`
    `github.com/cloudwego/frugal/internal/rt`
)

type Instr struct {
    Op OpCode
    Uv int32
    Iv int64
    To int
    Vt *rt.GoType
}

type (
    Program  []Instr
    Compiler map[reflect.Type]bool
)

func (self Instr) Disassemble() string {
    switch self.Op {
        case OP_size_check    : fallthrough
        case OP_size_const    : fallthrough
        case OP_size_map      : fallthrough
        case OP_seek          : fallthrough
        case OP_sint          : fallthrough
        case OP_length        : return fmt.Sprintf("%-18s%d", self.Op, self.Iv)
        case OP_size_dyn      : fallthrough
        case OP_memcpy_be     : return fmt.Sprintf("%-18s%d, %d", self.Op, self.Uv, self.Iv)
        case OP_size_defer    : fallthrough
        case OP_defer         : fallthrough
        case OP_map_begin     : fallthrough
        case OP_unique        : return fmt.Sprintf("%-18s%s", self.Op, self.Vt)
        case OP_byte          : return fmt.Sprintf("%-18s0x%02x", self.Op, self.Iv)
        case OP_word          : return fmt.Sprintf("%-18s0x%04x", self.Op, self.Iv)
        case OP_long          : return fmt.Sprintf("%-18s0x%08x", self.Op, self.Iv)
        case OP_quad          : return fmt.Sprintf("%-18s0x%016x", self.Op, self.Iv)
        case OP_map_if_next   : fallthrough
        case OP_map_if_empty  : fallthrough
        case OP_list_if_next  : fallthrough
        case OP_list_if_empty : fallthrough
        case OP_goto          : fallthrough
        case OP_if_nil        : fallthrough
        case OP_if_hasbuf     : return fmt.Sprintf("%-18sL_%d", self.Op, self.To)
        default               : return self.Op.String()
    }
}

func (self Program) pc() int   { return len(self) }
func (self Program) pin(i int) { self[i].To = self.pc() }

func (self Program) tag(n int) {
    if n >= defs.StackSize {
        panic("type nesting too deep")
    }
}

func (self *Program) ins(iv Instr)                      { *self = append(*self, iv) }
func (self *Program) add(op OpCode)                     { self.ins(Instr{Op: op}) }
func (self *Program) jmp(op OpCode, to int)             { self.ins(Instr{Op: op, To: to})}
func (self *Program) i64(op OpCode, iv int64)           { self.ins(Instr{Op: op, Iv: iv})}
func (self *Program) rtt(op OpCode, vt reflect.Type)    { self.ins(Instr{Op: op, Vt: rt.UnpackType(vt)})}
func (self *Program) dyn(op OpCode, uv int32, iv int64) { self.ins(Instr{Op: op, Uv: uv, Iv: iv})}

func (self Program) Free() {
    freeProgram(self)
}

func (self Program) Disassemble() string {
    nb  := len(self)
    tab := make([]bool, nb + 1)
    ret := make([]string, 0, nb + 1)

    /* prescan to get all the labels */
    for _, ins := range self {
        if _OpBranches[ins.Op] {
            tab[ins.To] = true
        }
    }

    /* disassemble each instruction */
    for i, ins := range self {
        if !tab[i] {
            ret = append(ret, "    " + ins.Disassemble())
        } else {
            ret = append(ret, fmt.Sprintf("L_%d:\n    %s", i, ins.Disassemble()))
        }
    }

    /* add an "end" indicator, and join all the strings */
    if !tab[nb] {
        return strings.Join(append(ret, "    end"), "\n")
    } else {
        return strings.Join(append(ret, fmt.Sprintf("L_%d:", nb), "    end"), "\n")
    }
}

func CreateCompiler() Compiler {
    return newCompiler()
}

func (self Compiler) rescue(ep *error) {
    if val := recover(); val != nil {
        if err, ok := val.(error); ok {
            *ep = err
        } else {
            panic(val)
        }
    }
}

func (self Compiler) Free() {
    freeCompiler(self)
}

func (self Compiler) Compile(vt reflect.Type) (_ Program, err error) {
    ret := newProgram()
    vtp := defs.ParseType(vt, "")

    /* catch the exceptions, and free the type */
    defer self.rescue(&err)
    defer vtp.Free()

    /* object measuring */
    i := ret.pc()
    ret.add(OP_if_hasbuf)
    resetCompiler(self).measure(&ret, 0, vtp, ret.pc() + defs.MaxILBuffer / 2)

    /* object encoding */
    j := ret.pc()
    ret.add(OP_goto)
    ret.pin(i)
    resetCompiler(self).compile(&ret, 0, vtp, ret.pc() + defs.MaxILBuffer / 2)

    /* halt the program */
    ret.pin(j)
    ret.add(OP_halt)
    return Optimize(ret), nil
}

func (self Compiler) CompileAndFree(vt reflect.Type) (ret Program, err error) {
    ret, err = self.Compile(vt)
    self.Free()
    return
}