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vm: optimize Next() in Context

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Creating a new BinReader for every instruction is a bit too much and it adds
about 1% overhead on block import (and actually is quite visible in the VM
profiling statistics). So use a bit more ugly but efficient method.
This commit is contained in:
Roman Khimov 2019-12-13 19:31:13 +03:00
parent a9401e2ec7
commit c9257c3de4
1 changed files with 36 additions and 20 deletions
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40
pkg/vm/context.go
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@ -1,10 +1,10 @@
package vm
import (
"encoding/binary"
"errors"
"github.com/CityOfZion/neo-go/pkg/crypto/hash"
"github.com/CityOfZion/neo-go/pkg/io"
"github.com/CityOfZion/neo-go/pkg/util"
"github.com/CityOfZion/neo-go/pkg/vm/opcode"
)
@ -36,6 +36,8 @@ type Context struct {
scriptHash util.Uint160
}
var errNoInstParam = errors.New("failed to read instruction parameter")
// NewContext returns a new Context object.
func NewContext(b []byte) *Context {
return &Context{
@ -49,33 +51,44 @@ func NewContext(b []byte) *Context {
// its invocation the instruction pointer points to the instruction being
// returned.
func (c *Context) Next() (opcode.Opcode, []byte, error) {
var err error
c.ip = c.nextip
if c.ip >= len(c.prog) {
return opcode.RET, nil, nil
}
r := io.NewBinReaderFromBuf(c.prog[c.ip:])
var instrbyte = r.ReadB()
var instrbyte = c.prog[c.ip]
instr := opcode.Opcode(instrbyte)
c.nextip++
var numtoread int
switch instr {
case opcode.PUSHDATA1, opcode.SYSCALL:
var n = r.ReadB()
numtoread = int(n)
if c.nextip >= len(c.prog) {
err = errNoInstParam
} else {
numtoread = int(c.prog[c.nextip])
c.nextip++
}
case opcode.PUSHDATA2:
var n = r.ReadU16LE()
numtoread = int(n)
if c.nextip+1 >= len(c.prog) {
err = errNoInstParam
} else {
numtoread = int(binary.LittleEndian.Uint16(c.prog[c.nextip : c.nextip+2]))
c.nextip += 2
}
case opcode.PUSHDATA4:
var n = r.ReadU32LE()
if c.nextip+3 >= len(c.prog) {
err = errNoInstParam
} else {
var n = binary.LittleEndian.Uint32(c.prog[c.nextip : c.nextip+4])
if n > MaxItemSize {
return instr, nil, errors.New("parameter is too big")
}
numtoread = int(n)
c.nextip += 4
}
case opcode.JMP, opcode.JMPIF, opcode.JMPIFNOT, opcode.CALL, opcode.CALLED, opcode.CALLEDT:
numtoread = 2
case opcode.CALLI:
@ -92,11 +105,14 @@ func (c *Context) Next() (opcode.Opcode, []byte, error) {
return instr, nil, nil
}
}
parameter := make([]byte, numtoread)
r.ReadBytes(parameter)
if r.Err != nil {
return instr, nil, errors.New("failed to read instruction parameter")
if c.nextip+numtoread-1 >= len(c.prog) {
err = errNoInstParam
}
if err != nil {
return instr, nil, err
}
parameter := make([]byte, numtoread)
copy(parameter, c.prog[c.nextip:c.nextip+numtoread])
c.nextip += numtoread
return instr, parameter, nil
}