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authorFelix Lange <fjl@twurst.com>2015-05-29 20:40:45 +0800
committerFelix Lange <fjl@twurst.com>2015-06-03 22:25:05 +0800
commitea2718c9462ae351baab5eaa05a7e1ef9dc916fa (patch)
treedd91f4e77fc779ffd3170272ea9025bcdfc002ef
parentb4818a003aabb1722f8413ba98fa5b6262ef9673 (diff)
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core/vm: improve JUMPDEST analysis
* JUMPDEST analysis is faster because less type conversions are performed. * The map of JUMPDEST locations is now created lazily at the first JUMP. * The result of the analysis is kept around for recursive invocations through CALL/CALLCODE. Fixes #1147
-rw-r--r--core/vm/analysis.go41
-rw-r--r--core/vm/context.go11
-rw-r--r--core/vm/vm.go17
3 files changed, 44 insertions, 25 deletions
diff --git a/core/vm/analysis.go b/core/vm/analysis.go
index 264d55cb9..a7aa8da39 100644
--- a/core/vm/analysis.go
+++ b/core/vm/analysis.go
@@ -3,34 +3,45 @@ package vm
import (
"math/big"
- "gopkg.in/fatih/set.v0"
+ "github.com/ethereum/go-ethereum/common"
)
-type destinations struct {
- set *set.Set
-}
+var bigMaxUint64 = new(big.Int).SetUint64(^uint64(0))
-func (d *destinations) Has(dest *big.Int) bool {
- return d.set.Has(string(dest.Bytes()))
-}
+// 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{}
-func (d *destinations) Add(dest *big.Int) {
- d.set.Add(string(dest.Bytes()))
+// 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.
+ // Don't bother checking for JUMPDEST in that case.
+ if dest.Cmp(bigMaxUint64) > 0 {
+ return false
+ }
+ m, analysed := d[codehash]
+ if !analysed {
+ m = jumpdests(code)
+ d[codehash] = m
+ }
+ _, ok := m[dest.Uint64()]
+ return ok
}
-func analyseJumpDests(code []byte) (dests *destinations) {
- dests = &destinations{set.New()}
-
+// 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{})
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:
a := uint64(op) - uint64(PUSH1) + 1
-
pc += a
case JUMPDEST:
- dests.Add(big.NewInt(int64(pc)))
+ m[pc] = struct{}{}
}
}
- return
+ return m
}
diff --git a/core/vm/context.go b/core/vm/context.go
index 29bb9f74e..de03f84f0 100644
--- a/core/vm/context.go
+++ b/core/vm/context.go
@@ -16,6 +16,8 @@ type Context struct {
caller ContextRef
self ContextRef
+ jumpdests destinations // result of JUMPDEST analysis.
+
Code []byte
CodeAddr *common.Address
@@ -24,10 +26,17 @@ type Context struct {
Args []byte
}
-// Create a new context for the given data items
+// Create a new context for the given data items.
func NewContext(caller ContextRef, object ContextRef, value, gas, price *big.Int) *Context {
c := &Context{caller: caller, self: object, Args: nil}
+ if parent, ok := caller.(*Context); ok {
+ // Reuse JUMPDEST analysis from parent context if available.
+ c.jumpdests = parent.jumpdests
+ } else {
+ c.jumpdests = make(destinations)
+ }
+
// Gas should be a pointer so it can safely be reduced through the run
// This pointer will be off the state transition
c.Gas = gas //new(big.Int).Set(gas)
diff --git a/core/vm/vm.go b/core/vm/vm.go
index 6db99bdcc..0d8facbb6 100644
--- a/core/vm/vm.go
+++ b/core/vm/vm.go
@@ -72,17 +72,16 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
}
var (
- op OpCode
-
- destinations = analyseJumpDests(context.Code)
- mem = NewMemory()
- stack = newStack()
- pc = new(big.Int)
- statedb = self.env.State()
+ op OpCode
+ codehash = crypto.Sha3Hash(code)
+ mem = NewMemory()
+ stack = newStack()
+ pc = new(big.Int)
+ statedb = self.env.State()
jump = func(from *big.Int, to *big.Int) error {
- nop := context.GetOp(to)
- if !destinations.Has(to) {
+ if !context.jumpdests.has(codehash, code, to) {
+ nop := context.GetOp(to)
return fmt.Errorf("invalid jump destination (%v) %v", nop, to)
}