Merge pull request #3 from quilt/paygas-config

Add flag for paygas mode to EVM interpreter

core/vm/interpreter.go

@@ -38,6 +38,9 @@ type Config struct {
 	EVMInterpreter   string // External EVM interpreter options
 
 	ExtraEips []int // Additional EIPS that are to be enabled
+
+	// paygasMode sets the behavior of the PAYGAS opcode.
+	PaygasMode PaygasMode
 }
 
 // Interpreter is used to run Ethereum based contracts and will utilise the
@@ -83,6 +86,8 @@ type EVMInterpreter struct {
 	evm *EVM
 	cfg Config
 
+	paygasMode PaygasMode
+
 	intPool *intPool
 
 	hasher    keccakState // Keccak256 hasher instance shared across opcodes
@@ -128,6 +133,7 @@ func NewEVMInterpreter(evm *EVM, cfg Config) *EVMInterpreter {
 	}
 
 	return &EVMInterpreter{
+		paygasMode: cfg.PaygasMode,
 		evm: evm,
 		cfg: cfg,
 	}

core/vm/jump_table.go

@@ -63,6 +63,17 @@ var (
 // JumpTable contains the EVM opcodes supported at a given fork.
 type JumpTable [256]operation
 
+type PaygasMode = uint
+
+const (
+	// Calling the PAYGAS opcode does nothing.
+	PaygasNoOp PaygasMode = iota
+	// Execution terminates as soon as PAYGAS is called.
+	PaygasHalt
+	// Execution continues after PAYGAS is called.
+	PaygasContinue
+)
+
 func newAccountAbstractionInstructionSet() JumpTable {
 	instructionSet := newIstanbulInstructionSet()