91 lines
2.2 KiB
Go
91 lines
2.2 KiB
Go
package vm
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import (
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"math/big"
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"time"
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"github.com/ethereum/go-ethereum/logger"
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"github.com/ethereum/go-ethereum/logger/glog"
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)
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// optimeProgram optimises a JIT program creating segments out of program
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// instructions. Currently covered are multi-pushes and static jumps
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func optimiseProgram(program *Program) {
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var load []instruction
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var (
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statsJump = 0
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statsPush = 0
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)
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if glog.V(logger.Debug) {
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glog.Infof("optimising %x\n", program.Id[:4])
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tstart := time.Now()
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defer func() {
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glog.Infof("optimised %x done in %v with JMP: %d PSH: %d\n", program.Id[:4], time.Since(tstart), statsJump, statsPush)
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}()
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}
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for i := 0; i < len(program.instructions); i++ {
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instr := program.instructions[i].(instruction)
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switch {
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case instr.op.IsPush():
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load = append(load, instr)
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case instr.op.IsStaticJump():
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if len(load) == 0 {
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continue
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}
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// if the push load is greater than 1, finalise that
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// segment first
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if len(load) > 2 {
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seg, size := makePushSeg(load[:len(load)-1])
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program.instructions[i-size-1] = seg
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statsPush++
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}
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// create a segment consisting of a pre determined
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// jump, destination and validity.
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seg := makeStaticJumpSeg(load[len(load)-1].data, program)
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program.instructions[i-1] = seg
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statsJump++
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load = nil
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default:
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// create a new N pushes segment
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if len(load) > 1 {
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seg, size := makePushSeg(load)
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program.instructions[i-size] = seg
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statsPush++
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}
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load = nil
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}
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}
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}
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// makePushSeg creates a new push segment from N amount of push instructions
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func makePushSeg(instrs []instruction) (pushSeg, int) {
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var (
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data []*big.Int
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gas = new(big.Int)
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)
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for _, instr := range instrs {
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data = append(data, instr.data)
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gas.Add(gas, instr.gas)
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}
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return pushSeg{data, gas}, len(instrs)
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}
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// makeStaticJumpSeg creates a new static jump segment from a predefined
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// destination (PUSH, JUMP).
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func makeStaticJumpSeg(to *big.Int, program *Program) jumpSeg {
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gas := new(big.Int)
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gas.Add(gas, _baseCheck[PUSH1].gas)
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gas.Add(gas, _baseCheck[JUMP].gas)
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contract := &Contract{Code: program.code}
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pos, err := jump(program.mapping, program.destinations, contract, to)
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return jumpSeg{pos, err, gas}
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}
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