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.

2 files changed, 4 insertions, 4 deletions

diff --git a/eth/api.go b/eth/api.go
index 9e25c3b2d..f077e348c 100644
--- a/eth/api.go
+++ b/eth/api.go
@@ -532,7 +532,7 @@ func (api *PrivateDebugAPI) TraceTransaction(ctx context.Context, txHash common.
 
 		// Mutate the state if we haven't reached the tracing transaction yet
 		if uint64(idx) < txIndex {
-			vmenv := vm.NewEnvironment(context, stateDb, api.config, vm.Config{})
+			vmenv := vm.NewEVM(context, stateDb, api.config, vm.Config{})
 			_, _, err := core.ApplyMessage(vmenv, msg, new(core.GasPool).AddGas(tx.Gas()))
 			if err != nil {
 				return nil, fmt.Errorf("mutation failed: %v", err)
@@ -541,7 +541,7 @@ func (api *PrivateDebugAPI) TraceTransaction(ctx context.Context, txHash common.
 			continue
 		}
 
-		vmenv := vm.NewEnvironment(context, stateDb, api.config, vm.Config{Debug: true, Tracer: tracer})
+		vmenv := vm.NewEVM(context, stateDb, api.config, vm.Config{Debug: true, Tracer: tracer})
 		ret, gas, err := core.ApplyMessage(vmenv, msg, new(core.GasPool).AddGas(tx.Gas()))
 		if err != nil {
 			return nil, fmt.Errorf("tracing failed: %v", err)
diff --git a/eth/api_backend.go b/eth/api_backend.go
index f33b6f7e1..801b6a4f6 100644
--- a/eth/api_backend.go
+++ b/eth/api_backend.go
@@ -106,14 +106,14 @@ func (b *EthApiBackend) GetTd(blockHash common.Hash) *big.Int {
 	return b.eth.blockchain.GetTdByHash(blockHash)
 }
 
-func (b *EthApiBackend) GetVMEnv(ctx context.Context, msg core.Message, state ethapi.State, header *types.Header) (*vm.Environment, func() error, error) {
+func (b *EthApiBackend) GetVMEnv(ctx context.Context, msg core.Message, state ethapi.State, header *types.Header) (*vm.EVM, func() error, error) {
 	statedb := state.(EthApiState).state
 	from := statedb.GetOrNewStateObject(msg.From())
 	from.SetBalance(common.MaxBig)
 	vmError := func() error { return nil }
 
 	context := core.NewEVMContext(msg, header, b.eth.BlockChain())
-	return vm.NewEnvironment(context, statedb, b.eth.chainConfig, vm.Config{}), vmError, nil
+	return vm.NewEVM(context, statedb, b.eth.chainConfig, vm.Config{}), vmError, nil
 }
 
 func (b *EthApiBackend) SendTx(ctx context.Context, signedTx *types.Transaction) error {