From c3c07bc75552286b9f3b2d11fcd503c7d4f1fc30 Mon Sep 17 00:00:00 2001
From: Martin Holst Swende <martin@swende.se>
Date: Mon, 16 Apr 2018 09:44:10 +0200
Subject: [PATCH] core/vm: don't check code for non-existing accounts

---
 core/vm/contract.go | 12 ++++++++++++
 core/vm/evm.go      | 31 ++++++++++++++++++++++++-------
 2 files changed, 36 insertions(+), 7 deletions(-)

diff --git a/core/vm/contract.go b/core/vm/contract.go
index b466681dbd..63c39e4b94 100644
--- a/core/vm/contract.go
+++ b/core/vm/contract.go
@@ -64,6 +64,18 @@ type Contract struct {
 	DelegateCall bool
 }
 
+func NewPrecompiledContract( caller ContractRef,  object ContractRef,value *big.Int, gas uint64) *Contract{
+
+	c := &Contract{CallerAddress: caller.Address(), caller: caller, self: object, Args: nil}
+	// 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
+	// ensures a value is set
+	c.value = value
+	return c
+
+}
+
 // NewContract returns a new contract environment for the execution of EVM.
 func NewContract(caller ContractRef, object ContractRef, value *big.Int, gas uint64) *Contract {
 	c := &Contract{CallerAddress: caller.Address(), caller: caller, self: object, Args: nil}
diff --git a/core/vm/evm.go b/core/vm/evm.go
index 988fdccee7..3d1de43fe0 100644
--- a/core/vm/evm.go
+++ b/core/vm/evm.go
@@ -167,7 +167,8 @@ func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas
 		to       = AccountRef(addr)
 		snapshot = evm.StateDB.Snapshot()
 	)
-	if !evm.StateDB.Exist(addr) {
+	exists := evm.StateDB.Exist(addr)
+	if !exists{
 		if evm.BlockContext.Precompiles[addr] == nil && evm.ChainConfig().IsEIP158(evm.BlockContext.BlockNumber) && value.Sign() == 0 {
 			// Calling a non existing account, don't do antything, but ping the tracer
 			if evm.vmConfig.Debug && evm.depth == 0 {
@@ -180,9 +181,17 @@ func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas
 	}
 	evm.Transfer(evm.StateDB, caller.Address(), to.Address(), value)
 
+	precompile, isPrecompile := evm.BlockContext.Precompiles[addr]
+
+	if !exists && !isPrecompile{
+		// Shortcut execution -- account didn't exist,
+		// so no need to lookup the code
+		// but make sure to set returndata to nil
+		evm.interpreter.returnData = nil
+		return nil, gas, nil
+	}
 	code := evm.StateDB.GetCode(addr)
 	codeHash := evm.StateDB.GetCodeHash(addr)
-	_, isPrecompile := evm.BlockContext.Precompiles[addr]
 
 	if !isPrecompile && len(code) == 0 {
 		// Shortcut execution if there is no code,
@@ -193,21 +202,29 @@ func (evm *EVM) Call(caller ContractRef, addr common.Address, input []byte, gas
 
 	// Initialise a new contract and set the code that is to be used by the EVM.
 	// The contract is a scoped environment for this execution context only.
-	contract := NewContract(caller, to, value, gas)
-	contract.SetCallCode(&addr, codeHash, code)
-
-	start := time.Now()
+	var contract *Contract
 
+	if!isPrecompile {
+		contract = NewContract(caller, to, value, gas)
+		contract.SetCallCode(&addr, codeHash, code)
+	}else{
+		contract = NewPrecompiledContract(caller, to, value, gas)
+	}
 	// Capture the tracer start/end events in debug mode
 	if evm.vmConfig.Debug && evm.depth == 0 {
+		start := time.Now()
 		evm.vmConfig.Tracer.CaptureStart(caller.Address(), addr, false, input, gas, value)
 
 		defer func() { // Lazy evaluation of the parameters
 			evm.vmConfig.Tracer.CaptureEnd(ret, gas-contract.Gas, time.Since(start), err)
 		}()
 	}
-	ret, err = run(evm, contract, input)
 
+	if!isPrecompile{
+		ret, err = evm.interpreter.Run(contract, input)
+	}else{
+		ret, err = RunPrecompiledContract(precompile, input, contract)
+	}
 	// When an error was returned by the EVM or when setting the creation code
 	// above we revert to the snapshot and consume any gas remaining. Additionally
 	// when we're in homestead this also counts for code storage gas errors.