Merge pull request #3111 from obscuren/gas-price-fork

core, core/vm: added gas price variance table (EIP #150)

7 files changed, 129 insertions, 20 deletions

diff --git a/core/config.go b/core/config.go
index c0d065a57..3ab04e520 100644
--- a/core/config.go
+++ b/core/config.go
@@ -21,6 +21,7 @@ import (
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/core/vm"
+	"github.com/ethereum/go-ethereum/params"
 )
 
 var ChainConfigNotFoundErr = errors.New("ChainConfig not found") // general config not found error
@@ -35,6 +36,8 @@ type ChainConfig struct {
 	DAOForkBlock   *big.Int `json:"daoForkBlock"`   // TheDAO hard-fork switch block (nil = no fork)
 	DAOForkSupport bool     `json:"daoForkSupport"` // Whether the nodes supports or opposes the DAO hard-fork
 
+	HomesteadGasRepriceBlock *big.Int `json:"homesteadGasRepriceBlock"` // Homestead gas reprice switch block (nil = no fork)
+
 	VmConfig vm.Config `json:"-"`
 }
 
@@ -45,3 +48,14 @@ func (c *ChainConfig) IsHomestead(num *big.Int) bool {
 	}
 	return num.Cmp(c.HomesteadBlock) >= 0
 }
+
+// GasTable returns the gas table corresponding to the current phase (homestead or homestead reprice).
+//
+// The returned GasTable's fields shouldn't, under any circumstances, be changed.
+func (c *ChainConfig) GasTable(num *big.Int) params.GasTable {
+	if c.HomesteadGasRepriceBlock == nil || num == nil || num.Cmp(c.HomesteadGasRepriceBlock) < 0 {
+		return params.GasTableHomestead
+	}
+
+	return params.GasTableHomesteadGasRepriceFork
+}
diff --git a/core/vm/environment.go b/core/vm/environment.go
index a4b2ac196..f8996e648 100644
--- a/core/vm/environment.go
+++ b/core/vm/environment.go
@@ -20,12 +20,16 @@ import (
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/params"
 )
 
 // RuleSet is an interface that defines the current rule set during the
 // execution of the EVM instructions (e.g. whether it's homestead)
 type RuleSet interface {
 	IsHomestead(*big.Int) bool
+	// GasTable returns the gas prices for this phase, which is based on
+	// block number passed in.
+	GasTable(*big.Int) params.GasTable
 }
 
 // Environment is an EVM requirement and helper which allows access to outside
diff --git a/core/vm/gas.go b/core/vm/gas.go
index eb2c16346..fdbc0df7f 100644
--- a/core/vm/gas.go
+++ b/core/vm/gas.go
@@ -35,8 +35,27 @@ var (
 	GasStop   = big.NewInt(0)
 
 	GasContractByte = big.NewInt(200)
+
+	n64 = big.NewInt(64)
 )
 
+// calcGas returns the actual gas cost of the call.
+//
+// The cost of gas was changed during the homestead price change HF. To allow for EIP150
+// to be implemented. The returned gas is gas - base * 63 / 64.
+func callGas(gasTable params.GasTable, availableGas, base, callCost *big.Int) *big.Int {
+	if gasTable.CreateBySuicide != nil {
+		availableGas = new(big.Int).Sub(availableGas, base)
+		g := new(big.Int).Div(availableGas, n64)
+		g.Sub(availableGas, g)
+
+		if g.Cmp(callCost) < 0 {
+			return g
+		}
+	}
+	return callCost
+}
+
 // baseCheck checks for any stack error underflows
 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
@@ -127,18 +146,19 @@ var _baseCheck = map[OpCode]req{
 	MSIZE:        {0, GasQuickStep, 1},
 	GAS:          {0, GasQuickStep, 1},
 	BLOCKHASH:    {1, GasExtStep, 1},
-	BALANCE:      {1, GasExtStep, 1},
-	EXTCODESIZE:  {1, GasExtStep, 1},
-	EXTCODECOPY:  {4, GasExtStep, 0},
+	BALANCE:      {1, Zero, 1},
+	EXTCODESIZE:  {1, Zero, 1},
+	EXTCODECOPY:  {4, Zero, 0},
 	SLOAD:        {1, params.SloadGas, 1},
 	SSTORE:       {2, Zero, 0},
 	SHA3:         {2, params.Sha3Gas, 1},
 	CREATE:       {3, params.CreateGas, 1},
-	CALL:         {7, params.CallGas, 1},
-	CALLCODE:     {7, params.CallGas, 1},
-	DELEGATECALL: {6, params.CallGas, 1},
-	JUMPDEST:     {0, params.JumpdestGas, 0},
+	// Zero is calculated in the gasSwitch
+	CALL:         {7, Zero, 1},
+	CALLCODE:     {7, Zero, 1},
+	DELEGATECALL: {6, Zero, 1},
 	SUICIDE:      {1, Zero, 0},
+	JUMPDEST:     {0, params.JumpdestGas, 0},
 	RETURN:       {2, Zero, 0},
 	PUSH1:        {0, GasFastestStep, 1},
 	DUP1:         {0, Zero, 1},
diff --git a/core/vm/instructions.go b/core/vm/instructions.go
index 79aee60d2..3352877c1 100644
--- a/core/vm/instructions.go
+++ b/core/vm/instructions.go
@@ -514,7 +514,12 @@ func opCreate(instr instruction, pc *uint64, env Environment, contract *Contract
 		input        = memory.Get(offset.Int64(), size.Int64())
 		gas          = new(big.Int).Set(contract.Gas)
 	)
-	contract.UseGas(contract.Gas)
+	if env.RuleSet().GasTable(env.BlockNumber()).CreateBySuicide != nil {
+		gas.Div(gas, n64)
+		gas = gas.Sub(contract.Gas, gas)
+	}
+
+	contract.UseGas(gas)
 	_, addr, suberr := env.Create(contract, input, gas, contract.Price, value)
 	// Push item on the stack based on the returned error. If the ruleset is
 	// homestead we must check for CodeStoreOutOfGasError (homestead only
diff --git a/core/vm/runtime/runtime.go b/core/vm/runtime/runtime.go
index 6d980cb32..343aee514 100644
--- a/core/vm/runtime/runtime.go
+++ b/core/vm/runtime/runtime.go
@@ -25,12 +25,16 @@ import (
 	"github.com/ethereum/go-ethereum/core/vm"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/params"
 )
 
 // The default, always homestead, rule set for the vm env
 type ruleSet struct{}
 
 func (ruleSet) IsHomestead(*big.Int) bool { return true }
+func (ruleSet) GasTable(*big.Int) params.GasTable {
+	return params.GasTableHomesteadGasRepriceFork
+}
 
 // Config is a basic type specifying certain configuration flags for running
 // the EVM.
diff --git a/core/vm/util_test.go b/core/vm/util_test.go
index f0d825555..5783ee015 100644
--- a/core/vm/util_test.go
+++ b/core/vm/util_test.go
@@ -16,10 +16,17 @@
 
 package vm
 
-import "math/big"
+import (
+	"math/big"
+
+	"github.com/ethereum/go-ethereum/params"
+)
 
 type ruleSet struct {
 	hs *big.Int
 }
 
 func (r ruleSet) IsHomestead(n *big.Int) bool { return n.Cmp(r.hs) >= 0 }
+func (r ruleSet) GasTable(*big.Int) params.GasTable {
+	return params.GasTableHomestead
+}
diff --git a/core/vm/vm.go b/core/vm/vm.go
index 033ada21c..fcffcf317 100644
--- a/core/vm/vm.go
+++ b/core/vm/vm.go
@@ -44,6 +44,7 @@ type EVM struct {
 	env       Environment
 	jumpTable vmJumpTable
 	cfg       Config
+	gasTable  params.GasTable
 }
 
 // New returns a new instance of the EVM.
@@ -52,6 +53,7 @@ func New(env Environment, cfg Config) *EVM {
 		env:       env,
 		jumpTable: newJumpTable(env.RuleSet(), env.BlockNumber()),
 		cfg:       cfg,
+		gasTable:  env.RuleSet().GasTable(env.BlockNumber()),
 	}
 }
 
@@ -169,7 +171,7 @@ func (evm *EVM) Run(contract *Contract, input []byte) (ret []byte, err error) {
 		// Get the memory location of pc
 		op = contract.GetOp(pc)
 		// calculate the new memory size and gas price for the current executing opcode
-		newMemSize, cost, err = calculateGasAndSize(evm.env, contract, caller, op, statedb, mem, stack)
+		newMemSize, cost, err = calculateGasAndSize(evm.gasTable, evm.env, contract, caller, op, statedb, mem, stack)
 		if err != nil {
 			return nil, err
 		}
@@ -234,7 +236,7 @@ func (evm *EVM) Run(contract *Contract, 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 calculateGasAndSize(env Environment, contract *Contract, caller ContractRef, op OpCode, statedb Database, mem *Memory, stack *Stack) (*big.Int, *big.Int, error) {
+func calculateGasAndSize(gasTable params.GasTable, env Environment, contract *Contract, caller ContractRef, op OpCode, statedb Database, mem *Memory, stack *Stack) (*big.Int, *big.Int, error) {
 	var (
 		gas                 = new(big.Int)
 		newMemSize *big.Int = new(big.Int)
@@ -246,6 +248,24 @@ func calculateGasAndSize(env Environment, contract *Contract, caller ContractRef
 
 	// stack Check, memory resize & gas phase
 	switch op {
+	case SUICIDE:
+		// if suicide is not nil: homestead gas fork
+		if gasTable.CreateBySuicide != nil {
+			gas.Set(gasTable.Suicide)
+			if !env.Db().Exist(common.BigToAddress(stack.data[len(stack.data)-1])) {
+				gas.Add(gas, gasTable.CreateBySuicide)
+			}
+		}
+
+		if !statedb.HasSuicided(contract.Address()) {
+			statedb.AddRefund(params.SuicideRefundGas)
+		}
+	case EXTCODESIZE:
+		gas.Set(gasTable.ExtcodeSize)
+	case BALANCE:
+		gas.Set(gasTable.Balance)
+	case SLOAD:
+		gas.Set(gasTable.SLoad)
 	case SWAP1, SWAP2, SWAP3, SWAP4, SWAP5, SWAP6, SWAP7, SWAP8, SWAP9, SWAP10, SWAP11, SWAP12, SWAP13, SWAP14, SWAP15, SWAP16:
 		n := int(op - SWAP1 + 2)
 		err := stack.require(n)
@@ -274,6 +294,8 @@ func calculateGasAndSize(env Environment, contract *Contract, caller ContractRef
 		gas.Add(gas, new(big.Int).Mul(mSize, params.LogDataGas))
 
 		newMemSize = calcMemSize(mStart, mSize)
+
+		quadMemGas(mem, newMemSize, gas)
 	case EXP:
 		gas.Add(gas, new(big.Int).Mul(big.NewInt(int64(len(stack.data[stack.len()-2].Bytes()))), params.ExpByteGas))
 	case SSTORE:
@@ -302,67 +324,100 @@ func calculateGasAndSize(env Environment, contract *Contract, caller ContractRef
 			g = params.SstoreResetGas
 		}
 		gas.Set(g)
-	case SUICIDE:
-		if !statedb.HasSuicided(contract.Address()) {
-			statedb.AddRefund(params.SuicideRefundGas)
-		}
 	case MLOAD:
 		newMemSize = calcMemSize(stack.peek(), u256(32))
+		quadMemGas(mem, newMemSize, gas)
 	case MSTORE8:
 		newMemSize = calcMemSize(stack.peek(), u256(1))
+		quadMemGas(mem, newMemSize, gas)
 	case MSTORE:
 		newMemSize = calcMemSize(stack.peek(), u256(32))
+		quadMemGas(mem, newMemSize, gas)
 	case RETURN:
 		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-2])
+		quadMemGas(mem, newMemSize, gas)
 	case SHA3:
 		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-2])
 
 		words := toWordSize(stack.data[stack.len()-2])
 		gas.Add(gas, words.Mul(words, params.Sha3WordGas))
+
+		quadMemGas(mem, newMemSize, gas)
 	case CALLDATACOPY:
 		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-3])
 
 		words := toWordSize(stack.data[stack.len()-3])
 		gas.Add(gas, words.Mul(words, params.CopyGas))
+
+		quadMemGas(mem, newMemSize, gas)
 	case CODECOPY:
 		newMemSize = calcMemSize(stack.peek(), stack.data[stack.len()-3])
 
 		words := toWordSize(stack.data[stack.len()-3])
 		gas.Add(gas, words.Mul(words, params.CopyGas))
+
+		quadMemGas(mem, newMemSize, gas)
 	case EXTCODECOPY:
+		gas.Set(gasTable.ExtcodeCopy)
+
 		newMemSize = calcMemSize(stack.data[stack.len()-2], stack.data[stack.len()-4])
 
 		words := toWordSize(stack.data[stack.len()-4])
 		gas.Add(gas, words.Mul(words, params.CopyGas))
 
+		quadMemGas(mem, newMemSize, gas)
 	case CREATE:
 		newMemSize = calcMemSize(stack.data[stack.len()-2], stack.data[stack.len()-3])
+
+		quadMemGas(mem, newMemSize, gas)
 	case CALL, CALLCODE:
-		gas.Add(gas, stack.data[stack.len()-1])
+		gas.Set(gasTable.Calls)
 
 		if op == CALL {
 			if !env.Db().Exist(common.BigToAddress(stack.data[stack.len()-2])) {
 				gas.Add(gas, params.CallNewAccountGas)
 			}
 		}
-
 		if len(stack.data[stack.len()-3].Bytes()) > 0 {
 			gas.Add(gas, params.CallValueTransferGas)
 		}
-
 		x := calcMemSize(stack.data[stack.len()-6], stack.data[stack.len()-7])
 		y := calcMemSize(stack.data[stack.len()-4], stack.data[stack.len()-5])
 
 		newMemSize = common.BigMax(x, y)
+
+		quadMemGas(mem, newMemSize, gas)
+
+		cg := callGas(gasTable, contract.Gas, gas, stack.data[stack.len()-1])
+		// Replace the stack item with the new gas calculation. This means that
+		// either the original item is left on the stack or the item is replaced by:
+		// (availableGas - gas) * 63 / 64
+		// We replace the stack item so that it's available when the opCall instruction is
+		// called. This information is otherwise lost due to the dependency on *current*
+		// available gas.
+		stack.data[stack.len()-1] = cg
+		gas.Add(gas, cg)
+
 	case DELEGATECALL:
-		gas.Add(gas, stack.data[stack.len()-1])
+		gas.Set(gasTable.Calls)
 
 		x := calcMemSize(stack.data[stack.len()-5], stack.data[stack.len()-6])
 		y := calcMemSize(stack.data[stack.len()-3], stack.data[stack.len()-4])
 
 		newMemSize = common.BigMax(x, y)
+
+		quadMemGas(mem, newMemSize, gas)
+
+		cg := callGas(gasTable, contract.Gas, gas, stack.data[stack.len()-1])
+		// Replace the stack item with the new gas calculation. This means that
+		// either the original item is left on the stack or the item is replaced by:
+		// (availableGas - gas) * 63 / 64
+		// We replace the stack item so that it's available when the opCall instruction is
+		// called.
+		stack.data[stack.len()-1] = cg
+		gas.Add(gas, cg)
+
 	}
-	quadMemGas(mem, newMemSize, gas)
 
 	return newMemSize, gas, nil
 }