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.

3 files changed, 5 insertions, 5 deletions

diff --git a/internal/ethapi/backend.go b/internal/ethapi/backend.go
index 36d7e754b..ebb14a5b5 100644
--- a/internal/ethapi/backend.go
+++ b/internal/ethapi/backend.go
@@ -51,7 +51,7 @@ type Backend interface {
 	GetBlock(ctx context.Context, blockHash common.Hash) (*types.Block, error)
 	GetReceipts(ctx context.Context, blockHash common.Hash) (types.Receipts, error)
 	GetTd(blockHash common.Hash) *big.Int
-	GetVMEnv(ctx context.Context, msg core.Message, state State, header *types.Header) (*vm.Environment, func() error, error)
+	GetVMEnv(ctx context.Context, msg core.Message, state State, header *types.Header) (*vm.EVM, func() error, error)
 	// TxPool API
 	SendTx(ctx context.Context, signedTx *types.Transaction) error
 	RemoveTx(txHash common.Hash)
diff --git a/internal/ethapi/tracer.go b/internal/ethapi/tracer.go
index 6d632376b..ef107fc42 100644
--- a/internal/ethapi/tracer.go
+++ b/internal/ethapi/tracer.go
@@ -278,7 +278,7 @@ func wrapError(context string, err error) error {
 }
 
 // CaptureState implements the Tracer interface to trace a single step of VM execution
-func (jst *JavascriptTracer) CaptureState(env *vm.Environment, pc uint64, op vm.OpCode, gas, cost *big.Int, memory *vm.Memory, stack *vm.Stack, contract *vm.Contract, depth int, err error) error {
+func (jst *JavascriptTracer) CaptureState(env *vm.EVM, pc uint64, op vm.OpCode, gas, cost *big.Int, memory *vm.Memory, stack *vm.Stack, contract *vm.Contract, depth int, err error) error {
 	if jst.err == nil {
 		jst.memory.memory = memory
 		jst.stack.stack = stack
diff --git a/internal/ethapi/tracer_test.go b/internal/ethapi/tracer_test.go
index 29814d783..65a23f55e 100644
--- a/internal/ethapi/tracer_test.go
+++ b/internal/ethapi/tracer_test.go
@@ -43,12 +43,12 @@ func (account) SetCode(common.Hash, []byte)                         {}
 func (account) ForEachStorage(cb func(key, value common.Hash) bool) {}
 
 func runTrace(tracer *JavascriptTracer) (interface{}, error) {
-	env := vm.NewEnvironment(vm.Context{}, nil, params.TestChainConfig, vm.Config{Debug: true, Tracer: tracer})
+	env := vm.NewEVM(vm.Context{}, nil, params.TestChainConfig, vm.Config{Debug: true, Tracer: tracer})
 
 	contract := vm.NewContract(account{}, account{}, big.NewInt(0), big.NewInt(10000))
 	contract.Code = []byte{byte(vm.PUSH1), 0x1, byte(vm.PUSH1), 0x1, 0x0}
 
-	_, err := env.EVM().Run(contract, []byte{})
+	_, err := env.Interpreter().Run(contract, []byte{})
 	if err != nil {
 		return nil, err
 	}
@@ -133,7 +133,7 @@ func TestHaltBetweenSteps(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	env := vm.NewEnvironment(vm.Context{}, nil, params.TestChainConfig, vm.Config{Debug: true, Tracer: tracer})
+	env := vm.NewEVM(vm.Context{}, nil, params.TestChainConfig, vm.Config{Debug: true, Tracer: tracer})
 	contract := vm.NewContract(&account{}, &account{}, big.NewInt(0), big.NewInt(0))
 
 	tracer.CaptureState(env, 0, 0, big.NewInt(0), big.NewInt(0), nil, nil, contract, 0, nil)