core/vm: improved EVM run loop & instruction calling (#3378)

The run loop, which previously contained custom opcode executes have been
removed and has been simplified to a few checks.

Each operation consists of 4 elements: execution function, gas cost function,
stack validation function and memory size function. The execution function
implements the operation's runtime behaviour, the gas cost function implements
the operation gas costs function and greatly depends on the memory and stack,
the stack validation function validates the stack and makes sure that enough
items can be popped off and pushed on and the memory size function calculates
the memory required for the operation and returns it.

This commit also allows the EVM to go unmetered. This is helpful for offline
operations such as contract calls.

1 files changed, 10 insertions, 11 deletions

diff --git a/core/state_processor.go b/core/state_processor.go
index 67a7ad5a1..82a371a9e 100644
--- a/core/state_processor.go
+++ b/core/state_processor.go
@@ -74,12 +74,12 @@ func (p *StateProcessor) Process(block *types.Block, statedb *state.StateDB, cfg
 	for i, tx := range block.Transactions() {
 		//fmt.Println("tx:", i)
 		statedb.StartRecord(tx.Hash(), block.Hash(), i)
-		receipt, logs, _, err := ApplyTransaction(p.config, p.bc, gp, statedb, header, tx, totalUsedGas, cfg)
+		receipt, _, err := ApplyTransaction(p.config, p.bc, gp, statedb, header, tx, totalUsedGas, cfg)
 		if err != nil {
 			return nil, nil, nil, err
 		}
 		receipts = append(receipts, receipt)
-		allLogs = append(allLogs, logs...)
+		allLogs = append(allLogs, receipt.Logs...)
 	}
 	AccumulateRewards(statedb, header, block.Uncles())
 
@@ -87,24 +87,23 @@ func (p *StateProcessor) Process(block *types.Block, statedb *state.StateDB, cfg
 }
 
 // ApplyTransaction attempts to apply a transaction to the given state database
-// and uses the input parameters for its environment.
-//
-// ApplyTransactions returns the generated receipts and vm logs during the
-// execution of the state transition phase.
-func ApplyTransaction(config *params.ChainConfig, bc *BlockChain, gp *GasPool, statedb *state.StateDB, header *types.Header, tx *types.Transaction, usedGas *big.Int, cfg vm.Config) (*types.Receipt, vm.Logs, *big.Int, error) {
+// and uses the input parameters for its environment. It returns the receipt
+// for the transaction, gas used and an error if the transaction failed,
+// indicating the block was invalid.
+func ApplyTransaction(config *params.ChainConfig, bc *BlockChain, gp *GasPool, statedb *state.StateDB, header *types.Header, tx *types.Transaction, usedGas *big.Int, cfg vm.Config) (*types.Receipt, *big.Int, error) {
 	msg, err := tx.AsMessage(types.MakeSigner(config, header.Number))
 	if err != nil {
-		return nil, nil, nil, err
+		return nil, nil, err
 	}
 	// Create a new context to be used in the EVM environment
 	context := NewEVMContext(msg, header, bc)
 	// Create a new environment which holds all relevant information
 	// about the transaction and calling mechanisms.
-	vmenv := vm.NewEnvironment(context, statedb, config, vm.Config{})
+	vmenv := vm.NewEVM(context, statedb, config, vm.Config{})
 	// Apply the transaction to the current state (included in the env)
 	_, gas, err := ApplyMessage(vmenv, msg, gp)
 	if err != nil {
-		return nil, nil, nil, err
+		return nil, nil, err
 	}
 
 	// Update the state with pending changes
@@ -125,7 +124,7 @@ func ApplyTransaction(config *params.ChainConfig, bc *BlockChain, gp *GasPool, s
 
 	glog.V(logger.Debug).Infoln(receipt)
 
-	return receipt, receipt.Logs, gas, err
+	return receipt, gas, err
 }
 
 // AccumulateRewards credits the coinbase of the given block with the