From 468501cb860508af55e1fcd586e1498df0a2d984 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Wed, 10 Jun 2015 10:44:46 +0200
Subject: [PATCH 01/16] core/vm: changed program counter to uint64

---
 core/vm/context.go |  8 ++++----
 core/vm/vm.go      | 18 +++++++++---------
 2 files changed, 13 insertions(+), 13 deletions(-)

diff --git a/core/vm/context.go b/core/vm/context.go
index de03f84f0..e33324b53 100644
--- a/core/vm/context.go
+++ b/core/vm/context.go
@@ -49,13 +49,13 @@ func NewContext(caller ContextRef, object ContextRef, value, gas, price *big.Int
 	return c
 }
 
-func (c *Context) GetOp(n *big.Int) OpCode {
+func (c *Context) GetOp(n uint64) OpCode {
 	return OpCode(c.GetByte(n))
 }
 
-func (c *Context) GetByte(n *big.Int) byte {
-	if n.Cmp(big.NewInt(int64(len(c.Code)))) < 0 {
-		return c.Code[n.Int64()]
+func (c *Context) GetByte(n uint64) byte {
+	if n < uint64(len(c.Code)) {
+		return c.Code[n]
 	}
 
 	return 0
diff --git a/core/vm/vm.go b/core/vm/vm.go
index 2bd950385..ed4157178 100644
--- a/core/vm/vm.go
+++ b/core/vm/vm.go
@@ -81,17 +81,17 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 		codehash = crypto.Sha3Hash(code)
 		mem      = NewMemory()
 		stack    = newStack()
-		pc       = new(big.Int)
+		pc       = uint64(0)
 		statedb  = self.env.State()
 
-		jump = func(from *big.Int, to *big.Int) error {
+		jump = func(from uint64, to *big.Int) error {
 			if !context.jumpdests.has(codehash, code, to) {
-				nop := context.GetOp(to)
+				nop := context.GetOp(to.Uint64())
 				return fmt.Errorf("invalid jump destination (%v) %v", nop, to)
 			}
 
 			self.Printf(" ~> %v", to)
-			pc = to
+			pc = to.Uint64()
 
 			self.Endl()
 
@@ -519,11 +519,11 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 			stack.push(self.env.GasLimit())
 
 		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 := big.NewInt(int64(op - PUSH1 + 1))
-			byts := getData(code, new(big.Int).Add(pc, big.NewInt(1)), a)
+			size := uint64(op - PUSH1 + 1)
+			byts := getData(code, new(big.Int).SetUint64(pc+1), new(big.Int).SetUint64(size))
 			// push value to stack
 			stack.push(common.Bytes2Big(byts))
-			pc.Add(pc, a)
+			pc += size
 
 			self.Printf(" => 0x%x", byts)
 		case POP:
@@ -603,7 +603,7 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 
 		case JUMPDEST:
 		case PC:
-			stack.push(pc)
+			stack.push(new(big.Int).SetUint64(pc))
 		case MSIZE:
 			stack.push(big.NewInt(int64(mem.Len())))
 		case GAS:
@@ -708,7 +708,7 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 			return nil, fmt.Errorf("Invalid opcode %x", op)
 		}
 
-		pc.Add(pc, One)
+		pc++
 
 		self.Endl()
 	}

From ff5b3ef0877978699235d20b3caa9890b35ec6f8 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Wed, 10 Jun 2015 10:59:44 +0200
Subject: [PATCH 02/16] core/vm: added structured logging

---
 core/execution.go |  4 ----
 core/vm/vm.go     | 26 ++++++++++++++++++++++----
 2 files changed, 22 insertions(+), 8 deletions(-)

diff --git a/core/execution.go b/core/execution.go
index 522c90449..9fb0210de 100644
--- a/core/execution.go
+++ b/core/execution.go
@@ -2,7 +2,6 @@ package core
 
 import (
 	"math/big"
-	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/state"
@@ -49,8 +48,6 @@ func (self *Execution) Create(caller vm.ContextRef) (ret []byte, err error, acco
 }
 
 func (self *Execution) exec(contextAddr *common.Address, code []byte, caller vm.ContextRef) (ret []byte, err error) {
-	start := time.Now()
-
 	env := self.env
 	evm := self.evm
 	if env.Depth() > int(params.CallCreateDepth.Int64()) {
@@ -96,7 +93,6 @@ func (self *Execution) exec(contextAddr *common.Address, code []byte, caller vm.
 	context.SetCallCode(contextAddr, code)
 
 	ret, err = evm.Run(context, self.input)
-	evm.Printf("message call took %v", time.Since(start)).Endl()
 	if err != nil {
 		env.State().Set(snapshot)
 	}
diff --git a/core/vm/vm.go b/core/vm/vm.go
index ed4157178..e6d4c8df2 100644
--- a/core/vm/vm.go
+++ b/core/vm/vm.go
@@ -11,10 +11,18 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 )
 
+type log struct {
+	op     OpCode
+	gas    *big.Int
+	memory []byte
+	stack  []*big.Int
+}
+
 type Vm struct {
 	env Environment
 
-	logTy  byte
+	// structured logging
+	Logs   []log
 	logStr string
 
 	err error
@@ -32,9 +40,7 @@ type Vm struct {
 }
 
 func New(env Environment) *Vm {
-	lt := LogTyPretty
-
-	return &Vm{debug: Debug, env: env, logTy: lt, Recoverable: true}
+	return &Vm{env: env, Recoverable: true}
 }
 
 func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
@@ -106,6 +112,8 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 		// Get the memory location of pc
 		op = context.GetOp(pc)
 
+		self.Log(op, context.Gas, mem, stack)
+
 		self.Printf("(pc) %-3d -o- %-14s (m) %-4d (s) %-4d ", pc, op.String(), mem.Len(), stack.len())
 		newMemSize, gas, err := self.calculateGasAndSize(context, caller, op, statedb, mem, stack)
 		if err != nil {
@@ -855,6 +863,16 @@ func (self *Vm) calculateGasAndSize(context *Context, caller ContextRef, op OpCo
 	return newMemSize, gas, nil
 }
 
+func (vm *Vm) Log(op OpCode, gas *big.Int, memory *Memory, stack *stack) {
+	if vm.debug {
+		mem := make([]byte, len(memory.store))
+		copy(mem, memory.store)
+		stck := make([]*big.Int, len(stack.data))
+		copy(stck, stack.data)
+		vm.Logs = append(vm.Logs, log{op, new(big.Int).Set(gas), mem, stck})
+	}
+}
+
 func (self *Vm) RunPrecompiled(p *PrecompiledAccount, callData []byte, context *Context) (ret []byte, err error) {
 	gas := p.Gas(len(callData))
 	if context.UseGas(gas) {

From 38c61f6f2567e7943c9a16e2be0a2bfedb3a1fb3 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Wed, 10 Jun 2015 12:23:49 +0200
Subject: [PATCH 03/16] core, core/vm: added structure logging

This also reduces the time required spend in the VM
---
 core/state_transition.go   |   4 +
 core/vm/environment.go     |  10 +++
 core/vm/gas.go             |   2 +-
 core/vm/stack.go           |  26 ++++---
 core/vm/virtual_machine.go |   2 -
 core/vm/vm.go              | 147 ++++---------------------------------
 core/vm_env.go             |  11 +++
 core/vm_logger.go          |  40 ++++++++++
 tests/helper/vm.go         |  11 ++-
 9 files changed, 104 insertions(+), 149 deletions(-)
 create mode 100644 core/vm_logger.go

diff --git a/core/state_transition.go b/core/state_transition.go
index 7672fa3ff..3dbc789f8 100644
--- a/core/state_transition.go
+++ b/core/state_transition.go
@@ -223,6 +223,10 @@ func (self *StateTransition) transitionState() (ret []byte, usedGas *big.Int, er
 		return nil, nil, InvalidTxError(err)
 	}
 
+	if vm.Debug {
+		VmStdErrFormat(vmenv.StructLogs())
+	}
+
 	self.refundGas()
 	self.state.AddBalance(self.coinbase, new(big.Int).Mul(self.gasUsed(), self.gasPrice))
 
diff --git a/core/vm/environment.go b/core/vm/environment.go
index 282d19578..31d5d5ea6 100644
--- a/core/vm/environment.go
+++ b/core/vm/environment.go
@@ -20,6 +20,8 @@ type Environment interface {
 	GasLimit() *big.Int
 	Transfer(from, to Account, amount *big.Int) error
 	AddLog(*state.Log)
+	AddStructLog(StructLog)
+	StructLogs() []StructLog
 
 	VmType() Type
 
@@ -31,6 +33,14 @@ type Environment interface {
 	Create(me ContextRef, data []byte, gas, price, value *big.Int) ([]byte, error, ContextRef)
 }
 
+type StructLog struct {
+	Pc     uint64
+	Op     OpCode
+	Gas    *big.Int
+	Memory []byte
+	Stack  []*big.Int
+}
+
 type Account interface {
 	SubBalance(amount *big.Int)
 	AddBalance(amount *big.Int)
diff --git a/core/vm/gas.go b/core/vm/gas.go
index 32f5fec04..1c29ccb65 100644
--- a/core/vm/gas.go
+++ b/core/vm/gas.go
@@ -21,7 +21,7 @@ var (
 	GasContractByte = big.NewInt(200)
 )
 
-func baseCheck(op OpCode, stack *stack, gas *big.Int) error {
+func baseCheck(op OpCode, stack *Stack, gas *big.Int) error {
 	// PUSH and DUP are a bit special. They all cost the same but we do want to have checking on stack push limit
 	// PUSH is also allowed to calculate the same price for all PUSHes
 	// DUP requirements are handled elsewhere (except for the stack limit check)
diff --git a/core/vm/stack.go b/core/vm/stack.go
index bb232d0b9..1d0a018c6 100644
--- a/core/vm/stack.go
+++ b/core/vm/stack.go
@@ -5,16 +5,20 @@ import (
 	"math/big"
 )
 
-func newStack() *stack {
-	return &stack{}
+func newStack() *Stack {
+	return &Stack{}
 }
 
-type stack struct {
+type Stack struct {
 	data []*big.Int
 	ptr  int
 }
 
-func (st *stack) push(d *big.Int) {
+func (st *Stack) Data() []*big.Int {
+	return st.data
+}
+
+func (st *Stack) push(d *big.Int) {
 	// NOTE push limit (1024) is checked in baseCheck
 	stackItem := new(big.Int).Set(d)
 	if len(st.data) > st.ptr {
@@ -25,36 +29,36 @@ func (st *stack) push(d *big.Int) {
 	st.ptr++
 }
 
-func (st *stack) pop() (ret *big.Int) {
+func (st *Stack) pop() (ret *big.Int) {
 	st.ptr--
 	ret = st.data[st.ptr]
 	return
 }
 
-func (st *stack) len() int {
+func (st *Stack) len() int {
 	return st.ptr
 }
 
-func (st *stack) swap(n int) {
+func (st *Stack) swap(n int) {
 	st.data[st.len()-n], st.data[st.len()-1] = st.data[st.len()-1], st.data[st.len()-n]
 }
 
-func (st *stack) dup(n int) {
+func (st *Stack) dup(n int) {
 	st.push(st.data[st.len()-n])
 }
 
-func (st *stack) peek() *big.Int {
+func (st *Stack) peek() *big.Int {
 	return st.data[st.len()-1]
 }
 
-func (st *stack) require(n int) error {
+func (st *Stack) require(n int) error {
 	if st.len() < n {
 		return fmt.Errorf("stack underflow (%d <=> %d)", len(st.data), n)
 	}
 	return nil
 }
 
-func (st *stack) Print() {
+func (st *Stack) Print() {
 	fmt.Println("### stack ###")
 	if len(st.data) > 0 {
 		for i, val := range st.data {
diff --git a/core/vm/virtual_machine.go b/core/vm/virtual_machine.go
index 6db284f42..1fd1dcd88 100644
--- a/core/vm/virtual_machine.go
+++ b/core/vm/virtual_machine.go
@@ -3,6 +3,4 @@ package vm
 type VirtualMachine interface {
 	Env() Environment
 	Run(context *Context, data []byte) ([]byte, error)
-	Printf(string, ...interface{}) VirtualMachine
-	Endl() VirtualMachine
 }
diff --git a/core/vm/vm.go b/core/vm/vm.go
index e6d4c8df2..7c4a7ce6d 100644
--- a/core/vm/vm.go
+++ b/core/vm/vm.go
@@ -7,24 +7,12 @@ import (
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/core/state"
 	"github.com/ethereum/go-ethereum/crypto"
-	"github.com/ethereum/go-ethereum/logger/glog"
 	"github.com/ethereum/go-ethereum/params"
 )
 
-type log struct {
-	op     OpCode
-	gas    *big.Int
-	memory []byte
-	stack  []*big.Int
-}
-
 type Vm struct {
 	env Environment
 
-	// structured logging
-	Logs   []log
-	logStr string
-
 	err error
 	// For logging
 	debug bool
@@ -40,7 +28,7 @@ type Vm struct {
 }
 
 func New(env Environment) *Vm {
-	return &Vm{env: env, Recoverable: true}
+	return &Vm{env: env, debug: Debug, Recoverable: true}
 }
 
 func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
@@ -54,8 +42,6 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 		price  = context.Price
 	)
 
-	self.Printf("(%d) (%x) %x (code=%d) gas: %v (d) %x", self.env.Depth(), caller.Address().Bytes()[:4], context.Address(), len(code), context.Gas, callData).Endl()
-
 	// User defer pattern to check for an error and, based on the error being nil or not, use all gas and return.
 	defer func() {
 		if self.After != nil {
@@ -63,7 +49,7 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 		}
 
 		if err != nil {
-			self.Printf(" %v", err).Endl()
+
 			// In case of a VM exception (known exceptions) all gas consumed (panics NOT included).
 			context.UseGas(context.Gas)
 
@@ -96,11 +82,8 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 				return fmt.Errorf("invalid jump destination (%v) %v", nop, to)
 			}
 
-			self.Printf(" ~> %v", to)
 			pc = to.Uint64()
 
-			self.Endl()
-
 			return nil
 		}
 	)
@@ -112,18 +95,14 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 		// Get the memory location of pc
 		op = context.GetOp(pc)
 
-		self.Log(op, context.Gas, mem, stack)
+		self.log(pc, op, context.Gas, mem, stack)
 
-		self.Printf("(pc) %-3d -o- %-14s (m) %-4d (s) %-4d ", pc, op.String(), mem.Len(), stack.len())
 		newMemSize, gas, err := self.calculateGasAndSize(context, caller, op, statedb, mem, stack)
 		if err != nil {
 			return nil, err
 		}
 
-		self.Printf("(g) %-3v (%v)", gas, context.Gas)
-
 		if !context.UseGas(gas) {
-			self.Endl()
 
 			tmp := new(big.Int).Set(context.Gas)
 
@@ -137,40 +116,33 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 		switch op {
 		case ADD:
 			x, y := stack.pop(), stack.pop()
-			self.Printf(" %v + %v", y, x)
 
 			base.Add(x, y)
 
 			U256(base)
 
-			self.Printf(" = %v", base)
 			// pop result back on the stack
 			stack.push(base)
 		case SUB:
 			x, y := stack.pop(), stack.pop()
-			self.Printf(" %v - %v", x, y)
 
 			base.Sub(x, y)
 
 			U256(base)
 
-			self.Printf(" = %v", base)
 			// pop result back on the stack
 			stack.push(base)
 		case MUL:
 			x, y := stack.pop(), stack.pop()
-			self.Printf(" %v * %v", y, x)
 
 			base.Mul(x, y)
 
 			U256(base)
 
-			self.Printf(" = %v", base)
 			// pop result back on the stack
 			stack.push(base)
 		case DIV:
 			x, y := stack.pop(), stack.pop()
-			self.Printf(" %v / %v", x, y)
 
 			if y.Cmp(common.Big0) != 0 {
 				base.Div(x, y)
@@ -178,14 +150,11 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 
 			U256(base)
 
-			self.Printf(" = %v", base)
 			// pop result back on the stack
 			stack.push(base)
 		case SDIV:
 			x, y := S256(stack.pop()), S256(stack.pop())
 
-			self.Printf(" %v / %v", x, y)
-
 			if y.Cmp(common.Big0) == 0 {
 				base.Set(common.Big0)
 			} else {
@@ -201,13 +170,10 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 				U256(base)
 			}
 
-			self.Printf(" = %v", base)
 			stack.push(base)
 		case MOD:
 			x, y := stack.pop(), stack.pop()
 
-			self.Printf(" %v %% %v", x, y)
-
 			if y.Cmp(common.Big0) == 0 {
 				base.Set(common.Big0)
 			} else {
@@ -216,13 +182,10 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 
 			U256(base)
 
-			self.Printf(" = %v", base)
 			stack.push(base)
 		case SMOD:
 			x, y := S256(stack.pop()), S256(stack.pop())
 
-			self.Printf(" %v %% %v", x, y)
-
 			if y.Cmp(common.Big0) == 0 {
 				base.Set(common.Big0)
 			} else {
@@ -238,20 +201,15 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 				U256(base)
 			}
 
-			self.Printf(" = %v", base)
 			stack.push(base)
 
 		case EXP:
 			x, y := stack.pop(), stack.pop()
 
-			self.Printf(" %v ** %v", x, y)
-
 			base.Exp(x, y, Pow256)
 
 			U256(base)
 
-			self.Printf(" = %v", base)
-
 			stack.push(base)
 		case SIGNEXTEND:
 			back := stack.pop()
@@ -268,15 +226,13 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 
 				num = U256(num)
 
-				self.Printf(" = %v", num)
-
 				stack.push(num)
 			}
 		case NOT:
 			stack.push(U256(new(big.Int).Not(stack.pop())))
 		case LT:
 			x, y := stack.pop(), stack.pop()
-			self.Printf(" %v < %v", x, y)
+
 			// x < y
 			if x.Cmp(y) < 0 {
 				stack.push(common.BigTrue)
@@ -285,7 +241,6 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 			}
 		case GT:
 			x, y := stack.pop(), stack.pop()
-			self.Printf(" %v > %v", x, y)
 
 			// x > y
 			if x.Cmp(y) > 0 {
@@ -296,7 +251,7 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 
 		case SLT:
 			x, y := S256(stack.pop()), S256(stack.pop())
-			self.Printf(" %v < %v", x, y)
+
 			// x < y
 			if x.Cmp(S256(y)) < 0 {
 				stack.push(common.BigTrue)
@@ -305,7 +260,6 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 			}
 		case SGT:
 			x, y := S256(stack.pop()), S256(stack.pop())
-			self.Printf(" %v > %v", x, y)
 
 			// x > y
 			if x.Cmp(y) > 0 {
@@ -316,7 +270,6 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 
 		case EQ:
 			x, y := stack.pop(), stack.pop()
-			self.Printf(" %v == %v", y, x)
 
 			// x == y
 			if x.Cmp(y) == 0 {
@@ -334,17 +287,14 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 
 		case AND:
 			x, y := stack.pop(), stack.pop()
-			self.Printf(" %v & %v", y, x)
 
 			stack.push(base.And(x, y))
 		case OR:
 			x, y := stack.pop(), stack.pop()
-			self.Printf(" %v | %v", x, y)
 
 			stack.push(base.Or(x, y))
 		case XOR:
 			x, y := stack.pop(), stack.pop()
-			self.Printf(" %v ^ %v", x, y)
 
 			stack.push(base.Xor(x, y))
 		case BYTE:
@@ -358,8 +308,6 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 				base.Set(common.BigFalse)
 			}
 
-			self.Printf(" => 0x%x", base.Bytes())
-
 			stack.push(base)
 		case ADDMOD:
 			x := stack.pop()
@@ -373,8 +321,6 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 				base = U256(base)
 			}
 
-			self.Printf(" %v + %v %% %v = %v", x, y, z, base)
-
 			stack.push(base)
 		case MULMOD:
 			x := stack.pop()
@@ -388,8 +334,6 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 				U256(base)
 			}
 
-			self.Printf(" %v + %v %% %v = %v", x, y, z, base)
-
 			stack.push(base)
 
 		case SHA3:
@@ -398,44 +342,35 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 
 			stack.push(common.BigD(data))
 
-			self.Printf(" => (%v) %x", size, data)
 		case ADDRESS:
 			stack.push(common.Bytes2Big(context.Address().Bytes()))
 
-			self.Printf(" => %x", context.Address())
 		case BALANCE:
 			addr := common.BigToAddress(stack.pop())
 			balance := statedb.GetBalance(addr)
 
 			stack.push(balance)
 
-			self.Printf(" => %v (%x)", balance, addr)
 		case ORIGIN:
 			origin := self.env.Origin()
 
 			stack.push(origin.Big())
 
-			self.Printf(" => %x", origin)
 		case CALLER:
 			caller := context.caller.Address()
 			stack.push(common.Bytes2Big(caller.Bytes()))
 
-			self.Printf(" => %x", caller)
 		case CALLVALUE:
 			stack.push(value)
 
-			self.Printf(" => %v", value)
 		case CALLDATALOAD:
 			data := getData(callData, stack.pop(), common.Big32)
 
-			self.Printf(" => 0x%x", data)
-
 			stack.push(common.Bytes2Big(data))
 		case CALLDATASIZE:
 			l := int64(len(callData))
 			stack.push(big.NewInt(l))
 
-			self.Printf(" => %d", l)
 		case CALLDATACOPY:
 			var (
 				mOff = stack.pop()
@@ -446,7 +381,6 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 
 			mem.Set(mOff.Uint64(), l.Uint64(), data)
 
-			self.Printf(" => [%v, %v, %v]", mOff, cOff, l)
 		case CODESIZE, EXTCODESIZE:
 			var code []byte
 			if op == EXTCODESIZE {
@@ -460,7 +394,6 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 			l := big.NewInt(int64(len(code)))
 			stack.push(l)
 
-			self.Printf(" => %d", l)
 		case CODECOPY, EXTCODECOPY:
 			var code []byte
 			if op == EXTCODECOPY {
@@ -480,12 +413,9 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 
 			mem.Set(mOff.Uint64(), l.Uint64(), codeCopy)
 
-			self.Printf(" => [%v, %v, %v] %x", mOff, cOff, l, codeCopy)
 		case GASPRICE:
 			stack.push(context.Price)
 
-			self.Printf(" => %x", context.Price)
-
 		case BLOCKHASH:
 			num := stack.pop()
 
@@ -496,33 +426,27 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 				stack.push(common.Big0)
 			}
 
-			self.Printf(" => 0x%x", stack.peek().Bytes())
 		case COINBASE:
 			coinbase := self.env.Coinbase()
 
 			stack.push(coinbase.Big())
 
-			self.Printf(" => 0x%x", coinbase)
 		case TIMESTAMP:
 			time := self.env.Time()
 
 			stack.push(big.NewInt(time))
 
-			self.Printf(" => 0x%x", time)
 		case NUMBER:
 			number := self.env.BlockNumber()
 
 			stack.push(U256(number))
 
-			self.Printf(" => 0x%x", number.Bytes())
 		case DIFFICULTY:
 			difficulty := self.env.Difficulty()
 
 			stack.push(difficulty)
 
-			self.Printf(" => 0x%x", difficulty.Bytes())
 		case GASLIMIT:
-			self.Printf(" => %v", self.env.GasLimit())
 
 			stack.push(self.env.GasLimit())
 
@@ -533,19 +457,16 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 			stack.push(common.Bytes2Big(byts))
 			pc += size
 
-			self.Printf(" => 0x%x", byts)
 		case POP:
 			stack.pop()
 		case DUP1, DUP2, DUP3, DUP4, DUP5, DUP6, DUP7, DUP8, DUP9, DUP10, DUP11, DUP12, DUP13, DUP14, DUP15, DUP16:
 			n := int(op - DUP1 + 1)
 			stack.dup(n)
 
-			self.Printf(" => [%d] 0x%x", n, stack.peek().Bytes())
 		case SWAP1, SWAP2, SWAP3, SWAP4, SWAP5, SWAP6, SWAP7, SWAP8, SWAP9, SWAP10, SWAP11, SWAP12, SWAP13, SWAP14, SWAP15, SWAP16:
 			n := int(op - SWAP1 + 2)
 			stack.swap(n)
 
-			self.Printf(" => [%d]", n)
 		case LOG0, LOG1, LOG2, LOG3, LOG4:
 			n := int(op - LOG0)
 			topics := make([]common.Hash, n)
@@ -558,38 +479,32 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 			log := state.NewLog(context.Address(), topics, data, self.env.BlockNumber().Uint64())
 			self.env.AddLog(log)
 
-			self.Printf(" => %v", log)
 		case MLOAD:
 			offset := stack.pop()
 			val := common.BigD(mem.Get(offset.Int64(), 32))
 			stack.push(val)
 
-			self.Printf(" => 0x%x", val.Bytes())
 		case MSTORE:
 			// pop value of the stack
 			mStart, val := stack.pop(), stack.pop()
 			mem.Set(mStart.Uint64(), 32, common.BigToBytes(val, 256))
 
-			self.Printf(" => 0x%x", val)
 		case MSTORE8:
 			off, val := stack.pop().Int64(), stack.pop().Int64()
 
 			mem.store[off] = byte(val & 0xff)
 
-			self.Printf(" => [%v] 0x%x", off, mem.store[off])
 		case SLOAD:
 			loc := common.BigToHash(stack.pop())
 			val := common.Bytes2Big(statedb.GetState(context.Address(), loc))
 			stack.push(val)
 
-			self.Printf(" {0x%x : 0x%x}", loc, val.Bytes())
 		case SSTORE:
 			loc := common.BigToHash(stack.pop())
 			val := stack.pop()
 
 			statedb.SetState(context.Address(), loc, val)
 
-			self.Printf(" {0x%x : 0x%x}", loc, val.Bytes())
 		case JUMP:
 			if err := jump(pc, stack.pop()); err != nil {
 				return nil, err
@@ -607,8 +522,6 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 				continue
 			}
 
-			self.Printf(" ~> false")
-
 		case JUMPDEST:
 		case PC:
 			stack.push(new(big.Int).SetUint64(pc))
@@ -617,7 +530,6 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 		case GAS:
 			stack.push(context.Gas)
 
-			self.Printf(" => %x", context.Gas)
 		case CREATE:
 
 			var (
@@ -627,14 +539,12 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 				gas          = new(big.Int).Set(context.Gas)
 				addr         common.Address
 			)
-			self.Endl()
 
 			context.UseGas(context.Gas)
 			ret, suberr, ref := self.env.Create(context, input, gas, price, value)
 			if suberr != nil {
 				stack.push(common.BigFalse)
 
-				self.Printf(" (*) 0x0 %v", suberr)
 			} else {
 				// gas < len(ret) * CreateDataGas == NO_CODE
 				dataGas := big.NewInt(int64(len(ret)))
@@ -659,7 +569,6 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 			retOffset, retSize := stack.pop(), stack.pop()
 
 			address := common.BigToAddress(addr)
-			self.Printf(" => %x", address).Endl()
 
 			// Get the arguments from the memory
 			args := mem.Get(inOffset.Int64(), inSize.Int64())
@@ -681,48 +590,40 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 			if err != nil {
 				stack.push(common.BigFalse)
 
-				self.Printf("%v").Endl()
 			} else {
 				stack.push(common.BigTrue)
 
 				mem.Set(retOffset.Uint64(), retSize.Uint64(), ret)
 			}
-			self.Printf("resume %x (%v)", context.Address(), context.Gas)
+
 		case RETURN:
 			offset, size := stack.pop(), stack.pop()
 			ret := mem.GetPtr(offset.Int64(), size.Int64())
 
-			self.Printf(" => [%v, %v] (%d) 0x%x", offset, size, len(ret), ret).Endl()
-
 			return context.Return(ret), nil
 		case SUICIDE:
 			receiver := statedb.GetOrNewStateObject(common.BigToAddress(stack.pop()))
 			balance := statedb.GetBalance(context.Address())
 
-			self.Printf(" => (%x) %v", receiver.Address().Bytes()[:4], balance)
-
 			receiver.AddBalance(balance)
 
 			statedb.Delete(context.Address())
 
 			fallthrough
 		case STOP: // Stop the context
-			self.Endl()
 
 			return context.Return(nil), nil
 		default:
-			self.Printf("(pc) %-3v Invalid opcode %x\n", pc, op).Endl()
 
 			return nil, fmt.Errorf("Invalid opcode %x", op)
 		}
 
 		pc++
 
-		self.Endl()
 	}
 }
 
-func (self *Vm) calculateGasAndSize(context *Context, caller ContextRef, op OpCode, statedb *state.StateDB, mem *Memory, stack *stack) (*big.Int, *big.Int, error) {
+func (self *Vm) calculateGasAndSize(context *Context, caller ContextRef, op OpCode, statedb *state.StateDB, mem *Memory, stack *Stack) (*big.Int, *big.Int, error) {
 	var (
 		gas                 = new(big.Int)
 		newMemSize *big.Int = new(big.Int)
@@ -863,26 +764,13 @@ func (self *Vm) calculateGasAndSize(context *Context, caller ContextRef, op OpCo
 	return newMemSize, gas, nil
 }
 
-func (vm *Vm) Log(op OpCode, gas *big.Int, memory *Memory, stack *stack) {
-	if vm.debug {
-		mem := make([]byte, len(memory.store))
-		copy(mem, memory.store)
-		stck := make([]*big.Int, len(stack.data))
-		copy(stck, stack.data)
-		vm.Logs = append(vm.Logs, log{op, new(big.Int).Set(gas), mem, stck})
-	}
-}
-
 func (self *Vm) RunPrecompiled(p *PrecompiledAccount, callData []byte, context *Context) (ret []byte, err error) {
 	gas := p.Gas(len(callData))
 	if context.UseGas(gas) {
 		ret = p.Call(callData)
-		self.Printf("NATIVE_FUNC => %x", ret)
-		self.Endl()
 
 		return context.Return(ret), nil
 	} else {
-		self.Printf("NATIVE_FUNC => failed").Endl()
 
 		tmp := new(big.Int).Set(context.Gas)
 
@@ -890,21 +778,14 @@ func (self *Vm) RunPrecompiled(p *PrecompiledAccount, callData []byte, context *
 	}
 }
 
-func (self *Vm) Printf(format string, v ...interface{}) VirtualMachine {
-	if self.debug {
-		self.logStr += fmt.Sprintf(format, v...)
+func (self *Vm) log(pc uint64, op OpCode, gas *big.Int, memory *Memory, stack *Stack) {
+	if Debug {
+		mem := make([]byte, len(memory.Data()))
+		copy(mem, memory.Data())
+		stck := make([]*big.Int, len(stack.Data()))
+		copy(stck, stack.Data())
+		self.env.AddStructLog(StructLog{pc, op, new(big.Int).Set(gas), mem, stck})
 	}
-
-	return self
-}
-
-func (self *Vm) Endl() VirtualMachine {
-	if self.debug {
-		glog.V(0).Infoln(self.logStr)
-		self.logStr = ""
-	}
-
-	return self
 }
 
 func (self *Vm) Env() Environment {
diff --git a/core/vm_env.go b/core/vm_env.go
index c439d2946..da862d5c8 100644
--- a/core/vm_env.go
+++ b/core/vm_env.go
@@ -16,6 +16,8 @@ type VMEnv struct {
 	depth int
 	chain *ChainManager
 	typ   vm.Type
+	// structured logging
+	logs []vm.StructLog
 }
 
 func NewEnv(state *state.StateDB, chain *ChainManager, msg Message, block *types.Block) *VMEnv {
@@ -47,6 +49,7 @@ func (self *VMEnv) GetHash(n uint64) common.Hash {
 
 	return common.Hash{}
 }
+
 func (self *VMEnv) AddLog(log *state.Log) {
 	self.state.AddLog(log)
 }
@@ -68,3 +71,11 @@ func (self *VMEnv) Create(me vm.ContextRef, data []byte, gas, price, value *big.
 	exe := NewExecution(self, nil, data, gas, price, value)
 	return exe.Create(me)
 }
+
+func (self *VMEnv) StructLogs() []vm.StructLog {
+	return self.logs
+}
+
+func (self *VMEnv) AddStructLog(log vm.StructLog) {
+	self.logs = append(self.logs, log)
+}
diff --git a/core/vm_logger.go b/core/vm_logger.go
new file mode 100644
index 000000000..84fa71b24
--- /dev/null
+++ b/core/vm_logger.go
@@ -0,0 +1,40 @@
+package core
+
+import (
+	"fmt"
+	"os"
+	"unicode/utf8"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core/vm"
+)
+
+func VmStdErrFormat(logs []vm.StructLog) {
+	fmt.Fprintf(os.Stderr, "VM Stats %d ops\n", len(logs))
+	for _, log := range logs {
+		fmt.Fprintf(os.Stderr, "PC %-3d - %-14s\n", log.Pc, log.Op)
+		fmt.Fprintln(os.Stderr, "STACK =", len(log.Stack))
+		for i, item := range log.Stack {
+			fmt.Fprintf(os.Stderr, "%04d: %x\n", i, common.LeftPadBytes(item.Bytes(), 32))
+		}
+
+		const maxMem = 10
+		addr := 0
+		fmt.Fprintln(os.Stderr, "MEM =", len(log.Memory))
+		for i := 0; i+16 <= len(log.Memory) && addr < maxMem; i += 16 {
+			data := log.Memory[i : i+16]
+			str := fmt.Sprintf("%04d: % x  ", addr*16, data)
+			for _, r := range data {
+				if r == 0 {
+					str += "."
+				} else if utf8.ValidRune(rune(r)) {
+					str += fmt.Sprintf("%s", string(r))
+				} else {
+					str += "?"
+				}
+			}
+			addr++
+			fmt.Fprintln(os.Stderr, str)
+		}
+	}
+}
diff --git a/tests/helper/vm.go b/tests/helper/vm.go
index 5f1a3e345..87b2e070d 100644
--- a/tests/helper/vm.go
+++ b/tests/helper/vm.go
@@ -27,9 +27,8 @@ type Env struct {
 	difficulty *big.Int
 	gasLimit   *big.Int
 
-	logs state.Logs
-
 	vmTest bool
+	logs   []vm.StructLog
 }
 
 func NewEnv(state *state.StateDB) *Env {
@@ -38,6 +37,14 @@ func NewEnv(state *state.StateDB) *Env {
 	}
 }
 
+func (self *Env) StructLogs() []vm.StructLog {
+	return self.logs
+}
+
+func (self *Env) AddStructLog(log vm.StructLog) {
+	self.logs = append(self.logs, log)
+}
+
 func NewEnvFromMap(state *state.StateDB, envValues map[string]string, exeValues map[string]string) *Env {
 	env := NewEnv(state)
 

From 6fb6e6679eb7c329ac9013d0c879a7c4b17daca5 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Wed, 10 Jun 2015 12:57:37 +0200
Subject: [PATCH 04/16] core/vm, core/state: added storage to structured vm
 logging

---
 core/state/state_object.go | 16 ++++++++++++++++
 core/vm/environment.go     | 11 ++++++-----
 core/vm/vm.go              | 13 ++++++++++---
 core/vm_logger.go          |  8 +++++++-
 4 files changed, 39 insertions(+), 9 deletions(-)

diff --git a/core/state/state_object.go b/core/state/state_object.go
index bfc4ebc6c..6d2455d79 100644
--- a/core/state/state_object.go
+++ b/core/state/state_object.go
@@ -336,6 +336,22 @@ func (self *StateObject) Nonce() uint64 {
 	return self.nonce
 }
 
+func (self *StateObject) EachStorage(cb func(key, value []byte)) {
+	// When iterating over the storage check the cache first
+	for h, v := range self.storage {
+		cb([]byte(h), v.Bytes())
+	}
+
+	it := self.State.trie.Iterator()
+	for it.Next() {
+		// ignore cached values
+		key := self.State.trie.GetKey(it.Key)
+		if _, ok := self.storage[string(key)]; !ok {
+			cb(key, it.Value)
+		}
+	}
+}
+
 //
 // Encoding
 //
diff --git a/core/vm/environment.go b/core/vm/environment.go
index 31d5d5ea6..25bd2515e 100644
--- a/core/vm/environment.go
+++ b/core/vm/environment.go
@@ -34,11 +34,12 @@ type Environment interface {
 }
 
 type StructLog struct {
-	Pc     uint64
-	Op     OpCode
-	Gas    *big.Int
-	Memory []byte
-	Stack  []*big.Int
+	Pc      uint64
+	Op      OpCode
+	Gas     *big.Int
+	Memory  []byte
+	Stack   []*big.Int
+	Storage map[common.Hash][]byte
 }
 
 type Account interface {
diff --git a/core/vm/vm.go b/core/vm/vm.go
index 7c4a7ce6d..e4f6e9268 100644
--- a/core/vm/vm.go
+++ b/core/vm/vm.go
@@ -95,7 +95,7 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 		// Get the memory location of pc
 		op = context.GetOp(pc)
 
-		self.log(pc, op, context.Gas, mem, stack)
+		self.log(pc, op, context.Gas, mem, stack, context)
 
 		newMemSize, gas, err := self.calculateGasAndSize(context, caller, op, statedb, mem, stack)
 		if err != nil {
@@ -778,13 +778,20 @@ func (self *Vm) RunPrecompiled(p *PrecompiledAccount, callData []byte, context *
 	}
 }
 
-func (self *Vm) log(pc uint64, op OpCode, gas *big.Int, memory *Memory, stack *Stack) {
+func (self *Vm) log(pc uint64, op OpCode, gas *big.Int, memory *Memory, stack *Stack, context *Context) {
 	if Debug {
 		mem := make([]byte, len(memory.Data()))
 		copy(mem, memory.Data())
 		stck := make([]*big.Int, len(stack.Data()))
 		copy(stck, stack.Data())
-		self.env.AddStructLog(StructLog{pc, op, new(big.Int).Set(gas), mem, stck})
+
+		object := context.self.(*state.StateObject)
+		storage := make(map[common.Hash][]byte)
+		object.EachStorage(func(k, v []byte) {
+			storage[common.BytesToHash(k)] = v
+		})
+
+		self.env.AddStructLog(StructLog{pc, op, new(big.Int).Set(gas), mem, stck, storage})
 	}
 }
 
diff --git a/core/vm_logger.go b/core/vm_logger.go
index 84fa71b24..d0742380e 100644
--- a/core/vm_logger.go
+++ b/core/vm_logger.go
@@ -12,7 +12,7 @@ import (
 func VmStdErrFormat(logs []vm.StructLog) {
 	fmt.Fprintf(os.Stderr, "VM Stats %d ops\n", len(logs))
 	for _, log := range logs {
-		fmt.Fprintf(os.Stderr, "PC %-3d - %-14s\n", log.Pc, log.Op)
+		fmt.Fprintf(os.Stderr, "PC %08d: %s\n", log.Pc, log.Op)
 		fmt.Fprintln(os.Stderr, "STACK =", len(log.Stack))
 		for i, item := range log.Stack {
 			fmt.Fprintf(os.Stderr, "%04d: %x\n", i, common.LeftPadBytes(item.Bytes(), 32))
@@ -36,5 +36,11 @@ func VmStdErrFormat(logs []vm.StructLog) {
 			addr++
 			fmt.Fprintln(os.Stderr, str)
 		}
+
+		fmt.Fprintln(os.Stderr, "STORAGE =", len(log.Storage))
+		for h, item := range log.Storage {
+			fmt.Fprintf(os.Stderr, "%x: %x\n", h, common.LeftPadBytes(item, 32))
+		}
+
 	}
 }

From 1774c494560507735d7b616456be60874063101f Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Wed, 10 Jun 2015 12:57:58 +0200
Subject: [PATCH 05/16] core: log tx count for each set of blocks we're
 importing

---
 core/chain_manager.go | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/core/chain_manager.go b/core/chain_manager.go
index 6897c453c..be64b54f4 100644
--- a/core/chain_manager.go
+++ b/core/chain_manager.go
@@ -567,6 +567,7 @@ func (self *ChainManager) InsertChain(chain types.Blocks) (int, error) {
 	go verifyNonces(self.pow, chain, nonceQuit, nonceDone)
 	defer close(nonceQuit)
 
+	txcount := 0
 	for i, block := range chain {
 		bstart := time.Now()
 		// Wait for block i's nonce to be verified before processing
@@ -625,6 +626,8 @@ func (self *ChainManager) InsertChain(chain types.Blocks) (int, error) {
 			return i, err
 		}
 
+		txcount += len(block.Transactions())
+
 		cblock := self.currentBlock
 		// Compare the TD of the last known block in the canonical chain to make sure it's greater.
 		// At this point it's possible that a different chain (fork) becomes the new canonical chain.
@@ -683,7 +686,7 @@ func (self *ChainManager) InsertChain(chain types.Blocks) (int, error) {
 	if (stats.queued > 0 || stats.processed > 0 || stats.ignored > 0) && bool(glog.V(logger.Info)) {
 		tend := time.Since(tstart)
 		start, end := chain[0], chain[len(chain)-1]
-		glog.Infof("imported %d block(s) (%d queued %d ignored) in %v. #%v [%x / %x]\n", stats.processed, stats.queued, stats.ignored, tend, end.Number(), start.Hash().Bytes()[:4], end.Hash().Bytes()[:4])
+		glog.Infof("imported %d block(s) (%d queued %d ignored) including %d txs in %v. #%v [%x / %x]\n", stats.processed, stats.queued, stats.ignored, txcount, tend, end.Number(), start.Hash().Bytes()[:4], end.Hash().Bytes()[:4])
 	}
 
 	go self.eventMux.Post(queueEvent)

From cf3aabb9d3dd7554d5859b36ed290f2e031ba33a Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Wed, 10 Jun 2015 13:52:38 +0200
Subject: [PATCH 06/16] miner: update gas used after tx proc for pending block

---
 miner/worker.go | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/miner/worker.go b/miner/worker.go
index 611445529..bd4bc0e3c 100644
--- a/miner/worker.go
+++ b/miner/worker.go
@@ -270,7 +270,6 @@ func (self *worker) wait() {
 
 func (self *worker) push() {
 	if atomic.LoadInt32(&self.mining) == 1 {
-		self.current.block.Header().GasUsed = self.current.totalUsedGas
 		self.current.block.SetRoot(self.current.state.Root())
 
 		// push new work to agents
@@ -510,6 +509,8 @@ func (self *worker) commitTransactions(transactions types.Transactions) {
 			current.tcount++
 		}
 	}
+
+	self.current.block.Header().GasUsed = self.current.totalUsedGas
 }
 
 func (self *worker) commitTransaction(tx *types.Transaction) error {

From f249ccaa89afa3340c3abd8578516b648e633e96 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Wed, 10 Jun 2015 16:46:43 +0200
Subject: [PATCH 07/16] cmd/evm: implements vm.Environment

---
 cmd/evm/main.go | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/cmd/evm/main.go b/cmd/evm/main.go
index 561f1a943..599721c89 100644
--- a/cmd/evm/main.go
+++ b/cmd/evm/main.go
@@ -104,6 +104,7 @@ type VMEnv struct {
 	depth int
 	Gas   *big.Int
 	time  int64
+	logs  []vm.StructLog
 }
 
 func NewEnv(state *state.StateDB, transactor common.Address, value *big.Int) *VMEnv {
@@ -133,6 +134,12 @@ func (self *VMEnv) GetHash(n uint64) common.Hash {
 	}
 	return common.Hash{}
 }
+func (self *VMEnv) AddStructLog(log vm.StructLog) {
+	self.logs = append(self.logs, log)
+}
+func (self *VMEnv) StructLogs() []vm.StructLog {
+	return self.logs
+}
 func (self *VMEnv) AddLog(log *state.Log) {
 	self.state.AddLog(log)
 }

From 065aff9ffa2bee1008d1f406328dd12a073cb239 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Wed, 10 Jun 2015 17:40:13 +0200
Subject: [PATCH 08/16] core/vm: documentation and name changes

---
 core/vm/environment.go |  4 ++++
 core/vm/vm.go          | 46 ++++++++++++++++++++++++++----------------
 2 files changed, 33 insertions(+), 17 deletions(-)

diff --git a/core/vm/environment.go b/core/vm/environment.go
index 25bd2515e..e61676409 100644
--- a/core/vm/environment.go
+++ b/core/vm/environment.go
@@ -8,6 +8,8 @@ import (
 	"github.com/ethereum/go-ethereum/core/state"
 )
 
+// Environment is is required by the virtual machine to get information from
+// it's own isolated environment. For an example see `core.VMEnv`
 type Environment interface {
 	State() *state.StateDB
 
@@ -33,6 +35,8 @@ type Environment interface {
 	Create(me ContextRef, data []byte, gas, price, value *big.Int) ([]byte, error, ContextRef)
 }
 
+// StructLog is emited to the Environment each cycle and lists information about the curent internal state
+// prior to the execution of the statement.
 type StructLog struct {
 	Pc      uint64
 	Op      OpCode
diff --git a/core/vm/vm.go b/core/vm/vm.go
index e4f6e9268..bf8bbcdc2 100644
--- a/core/vm/vm.go
+++ b/core/vm/vm.go
@@ -10,6 +10,7 @@ import (
 	"github.com/ethereum/go-ethereum/params"
 )
 
+// Vm implements VirtualMachine
 type Vm struct {
 	env Environment
 
@@ -27,11 +28,13 @@ type Vm struct {
 	After func(*Context, error)
 }
 
+// New returns a new Virtual Machine
 func New(env Environment) *Vm {
 	return &Vm{env: env, debug: Debug, Recoverable: true}
 }
 
-func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
+// Run loops and evaluates the contract's code with the given input data
+func (self *Vm) Run(context *Context, input []byte) (ret []byte, err error) {
 	self.env.SetDepth(self.env.Depth() + 1)
 	defer self.env.SetDepth(self.env.Depth() - 1)
 
@@ -59,7 +62,7 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 
 	if context.CodeAddr != nil {
 		if p := Precompiled[context.CodeAddr.Str()]; p != nil {
-			return self.RunPrecompiled(p, callData, context)
+			return self.RunPrecompiled(p, input, context)
 		}
 	}
 
@@ -69,13 +72,15 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 	}
 
 	var (
-		op       OpCode
-		codehash = crypto.Sha3Hash(code)
-		mem      = NewMemory()
-		stack    = newStack()
-		pc       = uint64(0)
-		statedb  = self.env.State()
+		op       OpCode                  // current opcode
+		codehash = crypto.Sha3Hash(code) // codehash is used when doing jump dest caching
+		mem      = NewMemory()           // bound memory
+		stack    = newStack()            // local stack
+		pc       = uint64(0)             // program counter
+		statedb  = self.env.State()      // current state
 
+		// jump evaluates and checks whether the given jump destination is a valid one
+		// if valid move the `pc` otherwise return an error.
 		jump = func(from uint64, to *big.Int) error {
 			if !context.jumpdests.has(codehash, code, to) {
 				nop := context.GetOp(to.Uint64())
@@ -97,20 +102,22 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 
 		self.log(pc, op, context.Gas, mem, stack, context)
 
+		// calculate the new memory size and gas price for the current executing opcode
 		newMemSize, gas, err := self.calculateGasAndSize(context, caller, op, statedb, mem, stack)
 		if err != nil {
 			return nil, err
 		}
 
+		// Use the calculated gas. When insufficient gas is present, use all gas and return an
+		// Out Of Gas error
 		if !context.UseGas(gas) {
-
 			tmp := new(big.Int).Set(context.Gas)
 
 			context.UseGas(context.Gas)
 
 			return context.Return(nil), OOG(gas, tmp)
 		}
-
+		// Resize the memory calculated previously
 		mem.Resize(newMemSize.Uint64())
 
 		switch op {
@@ -364,11 +371,11 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 			stack.push(value)
 
 		case CALLDATALOAD:
-			data := getData(callData, stack.pop(), common.Big32)
+			data := getData(input, stack.pop(), common.Big32)
 
 			stack.push(common.Bytes2Big(data))
 		case CALLDATASIZE:
-			l := int64(len(callData))
+			l := int64(len(input))
 			stack.push(big.NewInt(l))
 
 		case CALLDATACOPY:
@@ -377,7 +384,7 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 				cOff = stack.pop()
 				l    = stack.pop()
 			)
-			data := getData(callData, cOff, l)
+			data := getData(input, cOff, l)
 
 			mem.Set(mOff.Uint64(), l.Uint64(), data)
 
@@ -623,6 +630,8 @@ func (self *Vm) Run(context *Context, callData []byte) (ret []byte, err error) {
 	}
 }
 
+// calculateGasAndSize calculates the required given the opcode and stack items calculates the new memorysize for
+// the operation. This does not reduce gas or resizes the memory.
 func (self *Vm) calculateGasAndSize(context *Context, caller ContextRef, op OpCode, statedb *state.StateDB, mem *Memory, stack *Stack) (*big.Int, *big.Int, error) {
 	var (
 		gas                 = new(big.Int)
@@ -764,20 +773,22 @@ func (self *Vm) calculateGasAndSize(context *Context, caller ContextRef, op OpCo
 	return newMemSize, gas, nil
 }
 
-func (self *Vm) RunPrecompiled(p *PrecompiledAccount, callData []byte, context *Context) (ret []byte, err error) {
-	gas := p.Gas(len(callData))
+// RunPrecompile runs and evaluate the output of a precompiled contract defined in contracts.go
+func (self *Vm) RunPrecompiled(p *PrecompiledAccount, input []byte, context *Context) (ret []byte, err error) {
+	gas := p.Gas(len(input))
 	if context.UseGas(gas) {
-		ret = p.Call(callData)
+		ret = p.Call(input)
 
 		return context.Return(ret), nil
 	} else {
-
 		tmp := new(big.Int).Set(context.Gas)
 
 		return nil, OOG(gas, tmp)
 	}
 }
 
+// log emits a log event to the environment for each opcode encountered. This is not to be confused with the
+// LOG* opcode.
 func (self *Vm) log(pc uint64, op OpCode, gas *big.Int, memory *Memory, stack *Stack, context *Context) {
 	if Debug {
 		mem := make([]byte, len(memory.Data()))
@@ -795,6 +806,7 @@ func (self *Vm) log(pc uint64, op OpCode, gas *big.Int, memory *Memory, stack *S
 	}
 }
 
+// Environment returns the current workable state of the VM
 func (self *Vm) Env() Environment {
 	return self.env
 }

From fc2a061d510fbe09534ee1ade167d66c40ba7bf1 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Wed, 10 Jun 2015 17:45:21 +0200
Subject: [PATCH 09/16] core/vm: unexported stack again. No longer required

---
 core/vm/gas.go   |  2 +-
 core/vm/stack.go | 24 ++++++++++++------------
 core/vm/vm.go    |  6 +++---
 3 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/core/vm/gas.go b/core/vm/gas.go
index 1c29ccb65..32f5fec04 100644
--- a/core/vm/gas.go
+++ b/core/vm/gas.go
@@ -21,7 +21,7 @@ var (
 	GasContractByte = big.NewInt(200)
 )
 
-func baseCheck(op OpCode, stack *Stack, gas *big.Int) error {
+func baseCheck(op OpCode, stack *stack, gas *big.Int) error {
 	// PUSH and DUP are a bit special. They all cost the same but we do want to have checking on stack push limit
 	// PUSH is also allowed to calculate the same price for all PUSHes
 	// DUP requirements are handled elsewhere (except for the stack limit check)
diff --git a/core/vm/stack.go b/core/vm/stack.go
index 1d0a018c6..b551de272 100644
--- a/core/vm/stack.go
+++ b/core/vm/stack.go
@@ -5,20 +5,20 @@ import (
 	"math/big"
 )
 
-func newStack() *Stack {
-	return &Stack{}
+func newstack() *stack {
+	return &stack{}
 }
 
-type Stack struct {
+type stack struct {
 	data []*big.Int
 	ptr  int
 }
 
-func (st *Stack) Data() []*big.Int {
+func (st *stack) Data() []*big.Int {
 	return st.data
 }
 
-func (st *Stack) push(d *big.Int) {
+func (st *stack) push(d *big.Int) {
 	// NOTE push limit (1024) is checked in baseCheck
 	stackItem := new(big.Int).Set(d)
 	if len(st.data) > st.ptr {
@@ -29,36 +29,36 @@ func (st *Stack) push(d *big.Int) {
 	st.ptr++
 }
 
-func (st *Stack) pop() (ret *big.Int) {
+func (st *stack) pop() (ret *big.Int) {
 	st.ptr--
 	ret = st.data[st.ptr]
 	return
 }
 
-func (st *Stack) len() int {
+func (st *stack) len() int {
 	return st.ptr
 }
 
-func (st *Stack) swap(n int) {
+func (st *stack) swap(n int) {
 	st.data[st.len()-n], st.data[st.len()-1] = st.data[st.len()-1], st.data[st.len()-n]
 }
 
-func (st *Stack) dup(n int) {
+func (st *stack) dup(n int) {
 	st.push(st.data[st.len()-n])
 }
 
-func (st *Stack) peek() *big.Int {
+func (st *stack) peek() *big.Int {
 	return st.data[st.len()-1]
 }
 
-func (st *Stack) require(n int) error {
+func (st *stack) require(n int) error {
 	if st.len() < n {
 		return fmt.Errorf("stack underflow (%d <=> %d)", len(st.data), n)
 	}
 	return nil
 }
 
-func (st *Stack) Print() {
+func (st *stack) Print() {
 	fmt.Println("### stack ###")
 	if len(st.data) > 0 {
 		for i, val := range st.data {
diff --git a/core/vm/vm.go b/core/vm/vm.go
index bf8bbcdc2..fe380d79d 100644
--- a/core/vm/vm.go
+++ b/core/vm/vm.go
@@ -75,7 +75,7 @@ func (self *Vm) Run(context *Context, input []byte) (ret []byte, err error) {
 		op       OpCode                  // current opcode
 		codehash = crypto.Sha3Hash(code) // codehash is used when doing jump dest caching
 		mem      = NewMemory()           // bound memory
-		stack    = newStack()            // local stack
+		stack    = newstack()            // local stack
 		pc       = uint64(0)             // program counter
 		statedb  = self.env.State()      // current state
 
@@ -632,7 +632,7 @@ func (self *Vm) Run(context *Context, input []byte) (ret []byte, err error) {
 
 // calculateGasAndSize calculates the required given the opcode and stack items calculates the new memorysize for
 // the operation. This does not reduce gas or resizes the memory.
-func (self *Vm) calculateGasAndSize(context *Context, caller ContextRef, op OpCode, statedb *state.StateDB, mem *Memory, stack *Stack) (*big.Int, *big.Int, error) {
+func (self *Vm) calculateGasAndSize(context *Context, caller ContextRef, op OpCode, statedb *state.StateDB, mem *Memory, stack *stack) (*big.Int, *big.Int, error) {
 	var (
 		gas                 = new(big.Int)
 		newMemSize *big.Int = new(big.Int)
@@ -789,7 +789,7 @@ func (self *Vm) RunPrecompiled(p *PrecompiledAccount, input []byte, context *Con
 
 // log emits a log event to the environment for each opcode encountered. This is not to be confused with the
 // LOG* opcode.
-func (self *Vm) log(pc uint64, op OpCode, gas *big.Int, memory *Memory, stack *Stack, context *Context) {
+func (self *Vm) log(pc uint64, op OpCode, gas *big.Int, memory *Memory, stack *stack, context *Context) {
 	if Debug {
 		mem := make([]byte, len(memory.Data()))
 		copy(mem, memory.Data())

From 10af69b57c8022bb400e1f00bb3c6413e640a7e1 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Wed, 10 Jun 2015 19:56:40 +0200
Subject: [PATCH 10/16] core, core/vm: moved logger and added gas cost to
 struct logging

---
 core/state_transition.go            | 2 +-
 core/vm/environment.go              | 1 +
 core/{vm_logger.go => vm/logger.go} | 9 ++++-----
 core/vm/vm.go                       | 8 ++++----
 4 files changed, 10 insertions(+), 10 deletions(-)
 rename core/{vm_logger.go => vm/logger.go} (85%)

diff --git a/core/state_transition.go b/core/state_transition.go
index 3dbc789f8..fedea8021 100644
--- a/core/state_transition.go
+++ b/core/state_transition.go
@@ -224,7 +224,7 @@ func (self *StateTransition) transitionState() (ret []byte, usedGas *big.Int, er
 	}
 
 	if vm.Debug {
-		VmStdErrFormat(vmenv.StructLogs())
+		vm.StdErrFormat(vmenv.StructLogs())
 	}
 
 	self.refundGas()
diff --git a/core/vm/environment.go b/core/vm/environment.go
index e61676409..5c04e7022 100644
--- a/core/vm/environment.go
+++ b/core/vm/environment.go
@@ -41,6 +41,7 @@ type StructLog struct {
 	Pc      uint64
 	Op      OpCode
 	Gas     *big.Int
+	GasCost *big.Int
 	Memory  []byte
 	Stack   []*big.Int
 	Storage map[common.Hash][]byte
diff --git a/core/vm_logger.go b/core/vm/logger.go
similarity index 85%
rename from core/vm_logger.go
rename to core/vm/logger.go
index d0742380e..6d08cbebe 100644
--- a/core/vm_logger.go
+++ b/core/vm/logger.go
@@ -1,4 +1,4 @@
-package core
+package vm
 
 import (
 	"fmt"
@@ -6,13 +6,12 @@ import (
 	"unicode/utf8"
 
 	"github.com/ethereum/go-ethereum/common"
-	"github.com/ethereum/go-ethereum/core/vm"
 )
 
-func VmStdErrFormat(logs []vm.StructLog) {
+func StdErrFormat(logs []StructLog) {
 	fmt.Fprintf(os.Stderr, "VM Stats %d ops\n", len(logs))
 	for _, log := range logs {
-		fmt.Fprintf(os.Stderr, "PC %08d: %s\n", log.Pc, log.Op)
+		fmt.Fprintf(os.Stderr, "PC %08d: %s GAS: %v COST: %v\n", log.Pc, log.Op, log.Gas, log.GasCost)
 		fmt.Fprintln(os.Stderr, "STACK =", len(log.Stack))
 		for i, item := range log.Stack {
 			fmt.Fprintf(os.Stderr, "%04d: %x\n", i, common.LeftPadBytes(item.Bytes(), 32))
@@ -41,6 +40,6 @@ func VmStdErrFormat(logs []vm.StructLog) {
 		for h, item := range log.Storage {
 			fmt.Fprintf(os.Stderr, "%x: %x\n", h, common.LeftPadBytes(item, 32))
 		}
-
+		fmt.Fprintln(os.Stderr)
 	}
 }
diff --git a/core/vm/vm.go b/core/vm/vm.go
index fe380d79d..117331389 100644
--- a/core/vm/vm.go
+++ b/core/vm/vm.go
@@ -100,14 +100,14 @@ func (self *Vm) Run(context *Context, input []byte) (ret []byte, err error) {
 		// Get the memory location of pc
 		op = context.GetOp(pc)
 
-		self.log(pc, op, context.Gas, mem, stack, context)
-
 		// calculate the new memory size and gas price for the current executing opcode
 		newMemSize, gas, err := self.calculateGasAndSize(context, caller, op, statedb, mem, stack)
 		if err != nil {
 			return nil, err
 		}
 
+		self.log(pc, op, context.Gas, gas, mem, stack, context)
+
 		// Use the calculated gas. When insufficient gas is present, use all gas and return an
 		// Out Of Gas error
 		if !context.UseGas(gas) {
@@ -789,7 +789,7 @@ func (self *Vm) RunPrecompiled(p *PrecompiledAccount, input []byte, context *Con
 
 // log emits a log event to the environment for each opcode encountered. This is not to be confused with the
 // LOG* opcode.
-func (self *Vm) log(pc uint64, op OpCode, gas *big.Int, memory *Memory, stack *stack, context *Context) {
+func (self *Vm) log(pc uint64, op OpCode, gas, cost *big.Int, memory *Memory, stack *stack, context *Context) {
 	if Debug {
 		mem := make([]byte, len(memory.Data()))
 		copy(mem, memory.Data())
@@ -802,7 +802,7 @@ func (self *Vm) log(pc uint64, op OpCode, gas *big.Int, memory *Memory, stack *s
 			storage[common.BytesToHash(k)] = v
 		})
 
-		self.env.AddStructLog(StructLog{pc, op, new(big.Int).Set(gas), mem, stck, storage})
+		self.env.AddStructLog(StructLog{pc, op, new(big.Int).Set(gas), cost, mem, stck, storage})
 	}
 }
 

From f94c5473ad7139e42e22db8e099792638b73de77 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Wed, 10 Jun 2015 21:08:04 +0200
Subject: [PATCH 11/16] core/vm: fixed a bug where `Data` ignored the stack ptr

---
 core/vm/stack.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/core/vm/stack.go b/core/vm/stack.go
index b551de272..2be5c3dbe 100644
--- a/core/vm/stack.go
+++ b/core/vm/stack.go
@@ -15,7 +15,7 @@ type stack struct {
 }
 
 func (st *stack) Data() []*big.Int {
-	return st.data
+	return st.data[:st.ptr]
 }
 
 func (st *stack) push(d *big.Int) {

From e7627623b96d06f4963ae424d2cb41cf9ba86e72 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Wed, 10 Jun 2015 21:08:54 +0200
Subject: [PATCH 12/16] core/vm: reverse loop stack

---
 core/vm/logger.go | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/core/vm/logger.go b/core/vm/logger.go
index 6d08cbebe..96d07dab5 100644
--- a/core/vm/logger.go
+++ b/core/vm/logger.go
@@ -13,8 +13,9 @@ func StdErrFormat(logs []StructLog) {
 	for _, log := range logs {
 		fmt.Fprintf(os.Stderr, "PC %08d: %s GAS: %v COST: %v\n", log.Pc, log.Op, log.Gas, log.GasCost)
 		fmt.Fprintln(os.Stderr, "STACK =", len(log.Stack))
-		for i, item := range log.Stack {
-			fmt.Fprintf(os.Stderr, "%04d: %x\n", i, common.LeftPadBytes(item.Bytes(), 32))
+
+		for i := len(log.Stack) - 1; i >= 0; i-- {
+			fmt.Fprintf(os.Stderr, "%04d: %x\n", len(log.Stack)-i-1, common.LeftPadBytes(log.Stack[i].Bytes(), 32))
 		}
 
 		const maxMem = 10

From 5cfae0536f8499634c2fa2eba9a71fec1c0d417b Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Wed, 10 Jun 2015 21:09:12 +0200
Subject: [PATCH 13/16] cmd/evm: print trace when running programs

---
 cmd/evm/main.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/cmd/evm/main.go b/cmd/evm/main.go
index 599721c89..7c9d27fac 100644
--- a/cmd/evm/main.go
+++ b/cmd/evm/main.go
@@ -59,6 +59,7 @@ func main() {
 
 	logger.AddLogSystem(logger.NewStdLogSystem(os.Stdout, log.LstdFlags, logger.LogLevel(*loglevel)))
 
+	vm.Debug = true
 	db, _ := ethdb.NewMemDatabase()
 	statedb := state.New(common.Hash{}, db)
 	sender := statedb.CreateAccount(common.StringToAddress("sender"))
@@ -80,6 +81,8 @@ func main() {
 		fmt.Println(string(statedb.Dump()))
 	}
 
+	vm.StdErrFormat(vmenv.StructLogs())
+
 	var mem runtime.MemStats
 	runtime.ReadMemStats(&mem)
 	fmt.Printf("vm took %v\n", time.Since(tstart))

From 9e9bd3555789f069b6cb1950fe329d307f951eab Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Thu, 11 Jun 2015 11:44:39 +0200
Subject: [PATCH 14/16] cmd/geth: Added optional debug flag for reprocess block

---
 cmd/geth/admin.go | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/cmd/geth/admin.go b/cmd/geth/admin.go
index 13d10de32..b0b4e0954 100644
--- a/cmd/geth/admin.go
+++ b/cmd/geth/admin.go
@@ -271,9 +271,12 @@ func (js *jsre) debugBlock(call otto.FunctionCall) otto.Value {
 	}
 
 	tstart := time.Now()
-
 	old := vm.Debug
-	vm.Debug = true
+
+	if len(call.ArgumentList) > 1 {
+		vm.Debug, _ = call.Argument(1).ToBoolean()
+	}
+
 	_, err = js.ethereum.BlockProcessor().RetryProcess(block)
 	if err != nil {
 		fmt.Println(err)

From f599a1b5f143503817c9fa411854b9a8dac6ba72 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Thu, 11 Jun 2015 11:59:30 +0200
Subject: [PATCH 15/16] core/vm: added a comment regarding the uint64 vs
 *big.Int

---
 core/vm/vm.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/core/vm/vm.go b/core/vm/vm.go
index 117331389..4c0ab0f47 100644
--- a/core/vm/vm.go
+++ b/core/vm/vm.go
@@ -76,8 +76,10 @@ func (self *Vm) Run(context *Context, input []byte) (ret []byte, err error) {
 		codehash = crypto.Sha3Hash(code) // codehash is used when doing jump dest caching
 		mem      = NewMemory()           // bound memory
 		stack    = newstack()            // local stack
-		pc       = uint64(0)             // program counter
 		statedb  = self.env.State()      // current state
+		// For optimisation reason we're using uint64 as the program counter.
+		// It's theoretically possible to go above 2^64. The YP defines the PC to be uint256. Pratically much less so feasible.
+		pc = uint64(0) // program counter
 
 		// jump evaluates and checks whether the given jump destination is a valid one
 		// if valid move the `pc` otherwise return an error.

From 37111aa4bd215cfc8bcfb97cdc7e223649306196 Mon Sep 17 00:00:00 2001
From: obscuren <geffobscura@gmail.com>
Date: Thu, 11 Jun 2015 12:06:05 +0200
Subject: [PATCH 16/16] core: retry block now also parellise nonce checks

---
 core/block_processor.go | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/core/block_processor.go b/core/block_processor.go
index 190e72694..3ec3c585f 100644
--- a/core/block_processor.go
+++ b/core/block_processor.go
@@ -151,11 +151,17 @@ func (sm *BlockProcessor) RetryProcess(block *types.Block) (logs state.Logs, err
 		return nil, ParentError(header.ParentHash)
 	}
 	parent := sm.bc.GetBlock(header.ParentHash)
-	if !sm.Pow.Verify(block) {
+
+	// FIXME Change to full header validation. See #1225
+	errch := make(chan bool)
+	go func() { errch <- sm.Pow.Verify(block) }()
+
+	logs, err = sm.processWithParent(block, parent)
+	if !<-errch {
 		return nil, ValidationError("Block's nonce is invalid (= %x)", block.Nonce)
 	}
 
-	return sm.processWithParent(block, parent)
+	return logs, err
 }
 
 // Process block will attempt to process the given block's transactions and applies them