core/vm: simplify error handling in interpreter loop (#23952)

* core/vm: break loop on any error

* core/vm: move ErrExecutionReverted to opRevert()

* core/vm: use "stop token" to stop the loop

* core/vm: unconditionally pc++ in the loop

* core/vm: set return data in instruction impls

core/vm/errors.go

@@ -34,6 +34,10 @@ var (
 	ErrWriteProtection          = errors.New("write protection")
 	ErrReturnDataOutOfBounds    = errors.New("return data out of bounds")
 	ErrGasUintOverflow          = errors.New("gas uint64 overflow")
+
+	// errStopToken is an internal token indicating interpreter loop termination,
+	// never returned to outside callers.
+	errStopToken = errors.New("stop token")	
 )
 
 // ErrStackUnderflow wraps an evm error when the items on the stack less

core/vm/instructions.go

@@ -526,7 +526,7 @@ func opJump(pc *uint64, interpreter *EVMInterpreter, callContext *callCtx) ([]by
 	if !callContext.contract.validJumpdest(&pos) {
 		return nil, ErrInvalidJump
 	}
-	*pc = pos.Uint64()
+	*pc = pos.Uint64() - 1 // pc will be increased by the interpreter loop
 	return nil, nil
 }
 
@@ -536,9 +536,7 @@ func opJumpi(pc *uint64, interpreter *EVMInterpreter, callContext *callCtx) ([]b
 		if !callContext.contract.validJumpdest(&pos) {
 			return nil, ErrInvalidJump
 		}
-		*pc = pos.Uint64()
-	} else {
-		*pc++
+		*pc = pos.Uint64() - 1 // pc will be increased by the interpreter loop
 	}
 	return nil, nil
 }
@@ -592,8 +590,10 @@ func opCreate(pc *uint64, interpreter *EVMInterpreter, callContext *callCtx) ([]
 	callContext.contract.Gas += returnGas
 
 	if suberr == ErrExecutionReverted {
+		interpreter.returnData = res // set REVERT data to return data buffer
 		return res, nil
 	}
+	interpreter.returnData = nil // clear dirty return data buffer
 	return nil, nil
 }
 
@@ -623,8 +623,10 @@ func opCreate2(pc *uint64, interpreter *EVMInterpreter, callContext *callCtx) ([
 	callContext.contract.Gas += returnGas
 
 	if suberr == ErrExecutionReverted {
+		interpreter.returnData = res // set REVERT data to return data buffer
 		return res, nil
 	}
+	interpreter.returnData = nil // clear dirty return data buffer
 	return nil, nil
 }
 
@@ -656,6 +658,7 @@ func opCall(pc *uint64, interpreter *EVMInterpreter, callContext *callCtx) ([]by
 	}
 	callContext.contract.Gas += returnGas
 
+	interpreter.returnData = ret
 	return ret, nil
 }
 
@@ -687,6 +690,7 @@ func opCallCode(pc *uint64, interpreter *EVMInterpreter, callContext *callCtx) (
 	}
 	callContext.contract.Gas += returnGas
 
+	interpreter.returnData = ret
 	return ret, nil
 }
 
@@ -715,6 +719,7 @@ func opDelegateCall(pc *uint64, interpreter *EVMInterpreter, callContext *callCt
 	}
 	callContext.contract.Gas += returnGas
 
+	interpreter.returnData = ret
 	return ret, nil
 }
 
@@ -743,6 +748,7 @@ func opStaticCall(pc *uint64, interpreter *EVMInterpreter, callContext *callCtx)
 	}
 	callContext.contract.Gas += returnGas
 
+	interpreter.returnData = ret
 	return ret, nil
 }
 
@@ -750,18 +756,19 @@ func opReturn(pc *uint64, interpreter *EVMInterpreter, callContext *callCtx) ([]
 	offset, size := callContext.stack.pop(), callContext.stack.pop()
 	ret := callContext.memory.GetPtr(int64(offset.Uint64()), int64(size.Uint64()))
 
-	return ret, nil
+	return ret, errStopToken
 }
 
 func opRevert(pc *uint64, interpreter *EVMInterpreter, callContext *callCtx) ([]byte, error) {
 	offset, size := callContext.stack.pop(), callContext.stack.pop()
 	ret := callContext.memory.GetPtr(int64(offset.Uint64()), int64(size.Uint64()))
 
-	return ret, nil
+	interpreter.returnData = ret
+	return ret, ErrExecutionReverted
 }
 
 func opStop(pc *uint64, interpreter *EVMInterpreter, callContext *callCtx) ([]byte, error) {
-	return nil, nil
+	return nil, errStopToken
 }
 
 func opSuicide(pc *uint64, interpreter *EVMInterpreter, callContext *callCtx) ([]byte, error) {
@@ -769,7 +776,7 @@ func opSuicide(pc *uint64, interpreter *EVMInterpreter, callContext *callCtx) ([
 	balance := interpreter.evm.StateDB.GetBalance(callContext.contract.Address())
 	interpreter.evm.StateDB.AddBalance(common.Address(beneficiary.Bytes20()), balance)
 	interpreter.evm.StateDB.Suicide(callContext.contract.Address())
-	return nil, nil
+	return nil, errStopToken
 }
 
 // following functions are used by the instruction jump  table

core/vm/interpreter.go

@@ -273,24 +273,17 @@ func (in *EVMInterpreter) Run(contract *Contract, input []byte, readOnly bool) (
 
 		// execute the operation
 		res, err = operation.execute(&pc, in, callContext)
-		// if the operation clears the return data (e.g. it has returning data)
-		// set the last return to the result of the operation.
-		if operation.returns {
-			in.returnData = res
-		}
-		switch {
-		case err != nil:
-			return nil, err
-		case operation.reverts:
-			log.Debug("ErrExecutionReverted", "pc", pc, "reverts", operation.reverts, "err", err)
-			return res, ErrExecutionReverted
-		case operation.halts:
-			return res, nil
-		case !operation.jumps:
-			pc++
+		if err != nil {
+			break
 		}
+		pc++
 	}
-	return nil, nil
+	
+	if err == errStopToken {
+		err = nil // clear stop token error
+	}
+
+	return res, err
 }
 
 // CanRun tells if the contract, passed as an argument, can be

core/vm/jump_table.go

@@ -41,11 +41,7 @@ type operation struct {
 	// memorySize returns the memory size required for the operation
 	memorySize memorySizeFunc
 
-	halts   bool // indicates whether the operation should halt further execution
-	jumps   bool // indicates whether the program counter should not increment
-	writes  bool // determines whether this a state modifying operation
-	reverts bool // determines whether the operation reverts state (implicitly halts)
-	returns bool // determines whether the operations sets the return data content
+	writes bool // determines whether this a state modifying operation
 }
 
 var (
@@ -109,7 +105,6 @@ func newConstantinopleInstructionSet() JumpTable {
 		maxStack:    maxStack(4, 1),
 		memorySize:  memoryCreate2,
 		writes:      true,
-		returns:     true,
 	}
 	return instructionSet
 }
@@ -125,7 +120,6 @@ func newByzantiumInstructionSet() JumpTable {
 		minStack:    minStack(6, 1),
 		maxStack:    maxStack(6, 1),
 		memorySize:  memoryStaticCall,
-		returns:     true,
 	}
 	instructionSet[RETURNDATASIZE] = &operation{
 		execute:     opReturnDataSize,
@@ -147,8 +141,6 @@ func newByzantiumInstructionSet() JumpTable {
 		minStack:   minStack(2, 0),
 		maxStack:   maxStack(2, 0),
 		memorySize: memoryRevert,
-		reverts:    true,
-		returns:    true,
 	}
 	return instructionSet
 }
@@ -185,7 +177,6 @@ func newHomesteadInstructionSet() JumpTable {
 		minStack:    minStack(6, 1),
 		maxStack:    maxStack(6, 1),
 		memorySize:  memoryDelegateCall,
-		returns:     true,
 	}
 	return instructionSet
 }
@@ -199,7 +190,6 @@ func newFrontierInstructionSet() JumpTable {
 			constantGas: 0,
 			minStack:    minStack(0, 0),
 			maxStack:    maxStack(0, 0),
-			halts:       true,
 		},
 		ADD: {
 			execute:     opAdd,
@@ -509,14 +499,12 @@ func newFrontierInstructionSet() JumpTable {
 			constantGas: GasMidStep,
 			minStack:    minStack(1, 0),
 			maxStack:    maxStack(1, 0),
-			jumps:       true,
 		},
 		JUMPI: {
 			execute:     opJumpi,
 			constantGas: GasSlowStep,
 			minStack:    minStack(2, 0),
 			maxStack:    maxStack(2, 0),
-			jumps:       true,
 		},
 		PC: {
 			execute:     opPc,
@@ -974,7 +962,6 @@ func newFrontierInstructionSet() JumpTable {
 			maxStack:    maxStack(3, 1),
 			memorySize:  memoryCreate,
 			writes:      true,
-			returns:     true,
 		},
 		CALL: {
 			execute:     opCall,
@@ -983,7 +970,6 @@ func newFrontierInstructionSet() JumpTable {
 			minStack:    minStack(7, 1),
 			maxStack:    maxStack(7, 1),
 			memorySize:  memoryCall,
-			returns:     true,
 		},
 		CALLCODE: {
 			execute:     opCallCode,
@@ -992,7 +978,6 @@ func newFrontierInstructionSet() JumpTable {
 			minStack:    minStack(7, 1),
 			maxStack:    maxStack(7, 1),
 			memorySize:  memoryCall,
-			returns:     true,
 		},
 		RETURN: {
 			execute:    opReturn,
@@ -1000,14 +985,12 @@ func newFrontierInstructionSet() JumpTable {
 			minStack:   minStack(2, 0),
 			maxStack:   maxStack(2, 0),
 			memorySize: memoryReturn,
-			halts:      true,
 		},
 		SELFDESTRUCT: {
 			execute:    opSuicide,
 			dynamicGas: gasSelfdestruct,
 			minStack:   minStack(1, 0),
 			maxStack:   maxStack(1, 0),
-			halts:      true,
 			writes:     true,
 		},
 	}