Merge pull request #14570 from Arachnid/jumpdestanalysis

core/vm: Use a bitmap instead of a map for jumpdest analysis

Author: karalabe

core/vm/analysis.go

@@ -22,41 +22,39 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 )
 
-var bigMaxUint64 = new(big.Int).SetUint64(^uint64(0))
-
 // 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]map[uint64]struct{}
+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 64bits.
+	// PC cannot go beyond len(code) and certainly can't be bigger than 63bits.
 	// Don't bother checking for JUMPDEST in that case.
-	if dest.Cmp(bigMaxUint64) > 0 {
+	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
 	}
-	_, ok := m[dest.Uint64()]
-	return ok
+	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) map[uint64]struct{} {
-	m := make(map[uint64]struct{})
+func jumpdests(code []byte) []byte {
+	m := make([]byte, len(code)/8+1)
 	for pc := uint64(0); pc < uint64(len(code)); pc++ {
-		var op OpCode = OpCode(code[pc])
-		switch op {
-		case PUSH1, PUSH2, PUSH3, PUSH4, PUSH5, PUSH6, PUSH7, PUSH8, PUSH9, PUSH10, PUSH11, PUSH12, PUSH13, PUSH14, PUSH15, PUSH16, PUSH17, PUSH18, PUSH19, PUSH20, PUSH21, PUSH22, PUSH23, PUSH24, PUSH25, PUSH26, PUSH27, PUSH28, PUSH29, PUSH30, PUSH31, PUSH32:
+		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
-		case JUMPDEST:
-			m[pc] = struct{}{}
 		}
 	}
 	return m