mirror of
https://gitlab.com/pulsechaincom/erigon-pulse.git
synced 2024-12-25 21:17:16 +00:00
62 lines
1.9 KiB
Go
62 lines
1.9 KiB
Go
// Copyright 2014 The go-ethereum Authors
|
|
// This file is part of the go-ethereum library.
|
|
//
|
|
// The go-ethereum library is free software: you can redistribute it and/or modify
|
|
// it under the terms of the GNU Lesser General Public License as published by
|
|
// the Free Software Foundation, either version 3 of the License, or
|
|
// (at your option) any later version.
|
|
//
|
|
// The go-ethereum library is distributed in the hope that it will be useful,
|
|
// but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
|
// GNU Lesser General Public License for more details.
|
|
//
|
|
// You should have received a copy of the GNU Lesser General Public License
|
|
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
|
|
|
|
package vm
|
|
|
|
import (
|
|
"math/big"
|
|
|
|
"github.com/ethereum/go-ethereum/common"
|
|
)
|
|
|
|
// destinations stores one map per contract (keyed by hash of code).
|
|
// The maps contain an entry for each location of a JUMPDEST
|
|
// instruction.
|
|
type destinations map[common.Hash][]byte
|
|
|
|
// has checks whether code has a JUMPDEST at dest.
|
|
func (d destinations) has(codehash common.Hash, code []byte, dest *big.Int) bool {
|
|
// PC cannot go beyond len(code) and certainly can't be bigger than 63bits.
|
|
// Don't bother checking for JUMPDEST in that case.
|
|
udest := dest.Uint64()
|
|
if dest.BitLen() >= 63 || udest >= uint64(len(code)) {
|
|
return false
|
|
}
|
|
|
|
m, analysed := d[codehash]
|
|
if !analysed {
|
|
m = jumpdests(code)
|
|
d[codehash] = m
|
|
}
|
|
return (m[udest/8] & (1 << (udest % 8))) != 0
|
|
}
|
|
|
|
// jumpdests creates a map that contains an entry for each
|
|
// PC location that is a JUMPDEST instruction.
|
|
func jumpdests(code []byte) []byte {
|
|
m := make([]byte, len(code)/8+1)
|
|
for pc := uint64(0); pc < uint64(len(code)); pc++ {
|
|
op := OpCode(code[pc])
|
|
if op == JUMPDEST {
|
|
m[pc/8] |= 1 << (pc % 8)
|
|
} else if op >= PUSH1 && op <= PUSH32 {
|
|
a := uint64(op) - uint64(PUSH1) + 1
|
|
pc += a
|
|
}
|
|
}
|
|
return m
|
|
}
|