VM improvements, tests + bugfixes (#61)

* changed vm commands to match more of the standard

* fixed Uint16 jmp bug in VM

* moved test to vm + fixed numnotequal bug

* fixed broken tests

* moved compiler tests to vm tests

* added basic for support + inc and dec stmts

* bumped version

VERSION

@@ -1 +1 @@
-0.37.0
+0.38.0

pkg/vm/README.md

@@ -52,18 +52,18 @@ More information about standalone installation coming soon.
 NEO-GO-VM > help
 
 COMMAND    USAGE
-run        execute the current loaded script
-exit       exit the VM prompt
-estack     shows evaluation stack details
-break      place a breakpoint (> break 1)
-astack     shows alt stack details
-istack     show invocation stack details
-load       load a script into the VM (> load /path/to/script.avm)
-resume     resume the current loaded script
 step       step (n) instruction in the program (> step 10)
-help       show available commands
+ops        show the opcodes of the current loaded program
 ip         show the current instruction
-opcode     print the opcodes of the current loaded program
+estack     show evaluation stack details
+astack     show alt stack details
+istack     show invocation stack details
+run        execute the current loaded script
+cont       continue execution of the current loaded script
+help       show available commands
+exit       exit the VM prompt
+break      place a breakpoint (> break 1)
+load       load a script into the VM (> load /path/to/script.avm)
 ```
 
 ### Loading in your script

pkg/vm/cli/cli.go

@@ -28,14 +28,14 @@ var commands = map[string]command{
 	"exit":   {0, "exit the VM prompt", false},
 	"ip":     {0, "show the current instruction", true},
 	"break":  {1, "place a breakpoint (> break 1)", true},
-	"estack": {0, "shows evaluation stack details", false},
-	"astack": {0, "shows alt stack details", false},
+	"estack": {0, "show evaluation stack details", false},
+	"astack": {0, "show alt stack details", false},
 	"istack": {0, "show invocation stack details", false},
 	"load":   {1, "load a script into the VM (> load /path/to/script.avm)", false},
 	"run":    {0, "execute the current loaded script", true},
-	"resume": {0, "resume the current loaded script", true},
+	"cont":   {0, "continue execution of the current loaded script", true},
 	"step":   {0, "step (n) instruction in the program (> step 10)", true},
-	"opcode": {0, "print the opcodes of the current loaded program", true},
+	"ops":    {0, "show the opcodes of the current loaded program", true},
 }
 
 // VMCLI object for interacting with the VM.
@@ -46,7 +46,7 @@ type VMCLI struct {
 // New returns a new VMCLI object.
 func New() *VMCLI {
 	return &VMCLI{
-		vm: vm.New(nil),
+		vm: vm.New(nil, 0),
 	}
 }
 
@@ -98,13 +98,13 @@ func (c *VMCLI) handleCommand(cmd string, args ...string) {
 		fmt.Println(c.vm.Stack(cmd))
 
 	case "load":
-		if err := c.vm.Load(args[0]); err != nil {
+		if err := c.vm.LoadFile(args[0]); err != nil {
 			fmt.Println(err)
 		} else {
 			fmt.Printf("READY: loaded %d instructions\n", c.vm.Context().LenInstr())
 		}
 
-	case "run", "resume":
+	case "run", "cont":
 		c.vm.Run()
 
 	case "step":
@@ -122,15 +122,8 @@ func (c *VMCLI) handleCommand(cmd string, args ...string) {
 		c.vm.AddBreakPointRel(n)
 		c.vm.Run()
 
-	case "opcode":
-		prog := c.vm.Context().Program()
-
-		w := tabwriter.NewWriter(os.Stdout, 0, 0, 4, ' ', 0)
-		fmt.Fprintln(w, "INDEX\tOPCODE\tDESC\t")
-		for i := 0; i < len(prog); i++ {
-			fmt.Fprintf(w, "%d\t0x%2x\t%s\t\n", i, prog[i], vm.Opcode(prog[i]))
-		}
-		w.Flush()
+	case "ops":
+		c.vm.PrintOps()
 	}
 }
 

pkg/vm/compiler/codegen.go

@@ -266,9 +266,11 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 			log.Fatal("multiple returns not supported.")
 		}
 
-		emitOpcode(c.prog, vm.Ojmp)
-		emitOpcode(c.prog, vm.Opcode(0x03))
-		emitOpcode(c.prog, vm.Opush0)
+		// @OPTIMIZE: We could skip these 3 instructions for each return statement.
+		// To be backwards compatible we will put them them in.
+		l := c.newLabel()
+		emitJmp(c.prog, vm.Ojmp, int16(l))
+		c.setLabel(l)
 
 		if len(n.Results) > 0 {
 			ast.Walk(c, n.Results[0])
@@ -456,6 +458,19 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 	case *ast.UnaryExpr:
 		// TODO(@anthdm)
 
+	case *ast.IncDecStmt:
+		ast.Walk(c, n.X)
+		c.convertToken(n.Tok)
+
+		// For now only identifiers are supported for (post) for stmts.
+		// for i := 0; i < 10; i++ {}
+		// Where the post stmt is ( i++ )
+		if ident, ok := n.X.(*ast.Ident); ok {
+			pos := c.scope.loadLocal(ident.Name)
+			c.emitStoreLocal(pos)
+		}
+		return nil
+
 	case *ast.IndexExpr:
 		// Walk the expression, this could be either an Ident or SelectorExpr.
 		// This will load local whatever X is.
@@ -471,6 +486,32 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 			emitOpcode(c.prog, vm.Opickitem) // just pickitem here
 		}
 		return nil
+
+	case *ast.ForStmt:
+		var (
+			fstart = c.newLabel()
+			fend   = c.newLabel()
+		)
+
+		// Walk the initializer and condition.
+		ast.Walk(c, n.Init)
+
+		// Set label and walk the condition.
+		c.setLabel(fstart)
+		ast.Walk(c, n.Cond)
+
+		// Jump if the condition is false
+		emitJmp(c.prog, vm.Ojmpifnot, int16(fend))
+
+		// Walk body followed by the iterator (post stmt).
+		ast.Walk(c, n.Body)
+		ast.Walk(c, n.Post)
+
+		// Jump back to condition.
+		emitJmp(c.prog, vm.Ojmp, int16(fstart))
+		c.setLabel(fend)
+
+		return nil
 	}
 	return c
 }
@@ -572,8 +613,14 @@ func (c *codegen) convertToken(tok token.Token) {
 		emitOpcode(c.prog, vm.Ogt)
 	case token.GEQ:
 		emitOpcode(c.prog, vm.Ogte)
-	case token.EQL, token.NEQ:
+	case token.EQL:
 		emitOpcode(c.prog, vm.Onumequal)
+	case token.NEQ:
+		emitOpcode(c.prog, vm.Onumnotequal)
+	case token.DEC:
+		emitOpcode(c.prog, vm.Odec)
+	case token.INC:
+		emitOpcode(c.prog, vm.Oinc)
 	default:
 		log.Fatalf("compiler could not convert token: %s", tok)
 	}
@@ -653,8 +700,8 @@ func (c *codegen) writeJumps() {
 	for i, op := range b {
 		j := i + 1
 		switch vm.Opcode(op) {
-		case vm.Ojmpifnot, vm.Ojmpif, vm.Ocall:
-			index := binary.LittleEndian.Uint16(b[j : j+2])
+		case vm.Ojmp, vm.Ojmpifnot, vm.Ojmpif, vm.Ocall:
+			index := int16(binary.LittleEndian.Uint16(b[j : j+2]))
 			if int(index) > len(c.l) {
 				continue
 			}

pkg/vm/compiler/tests/compiler_test.go

@@ -1,63 +1,57 @@
 package compiler
 
 import (
-	"bytes"
-	"encoding/hex"
 	"fmt"
 	"os"
-	"strings"
 	"testing"
 	"text/tabwriter"
 
 	"github.com/CityOfZion/neo-go/pkg/vm"
-	"github.com/CityOfZion/neo-go/pkg/vm/compiler"
 )
 
 type testCase struct {
 	name   string
 	src    string
-	result string
+	result interface{}
 }
 
 func TestAllCases(t *testing.T) {
-	testCases := []testCase{}
-
 	// The Go language
-	testCases = append(testCases, builtinTestCases...)
-	testCases = append(testCases, assignTestCases...)
-	testCases = append(testCases, arrayTestCases...)
-	testCases = append(testCases, binaryExprTestCases...)
-	testCases = append(testCases, functionCallTestCases...)
-	testCases = append(testCases, boolTestCases...)
-	testCases = append(testCases, stringTestCases...)
-	testCases = append(testCases, structTestCases...)
-	testCases = append(testCases, ifStatementTestCases...)
-	testCases = append(testCases, customTypeTestCases...)
-	testCases = append(testCases, constantTestCases...)
-	testCases = append(testCases, importTestCases...)
+	//testCases = append(testCases, builtinTestCases...)
+	//testCases = append(testCases, arrayTestCases...)
+	//testCases = append(testCases, binaryExprTestCases...)
+	//testCases = append(testCases, functionCallTestCases...)
+	//testCases = append(testCases, boolTestCases...)
+	//testCases = append(testCases, stringTestCases...)
+	//testCases = append(testCases, structTestCases...)
+	//testCases = append(testCases, ifStatementTestCases...)
+	//testCases = append(testCases, customTypeTestCases...)
+	//testCases = append(testCases, constantTestCases...)
+	//testCases = append(testCases, importTestCases...)
+	//testCases = append(testCases, forTestCases...)
 
-	// Blockchain specific
-	testCases = append(testCases, storageTestCases...)
-	testCases = append(testCases, runtimeTestCases...)
+	//// Blockchain specific
+	//testCases = append(testCases, storageTestCases...)
+	//testCases = append(testCases, runtimeTestCases...)
 
-	for _, tc := range testCases {
-		b, err := compiler.Compile(strings.NewReader(tc.src), &compiler.Options{})
-		if err != nil {
-			t.Fatal(err)
-		}
+	//for _, tc := range testCases {
+	//	b, err := compiler.Compile(strings.NewReader(tc.src), &compiler.Options{})
+	//	if err != nil {
+	//		t.Fatal(err)
+	//	}
 
-		expectedResult, err := hex.DecodeString(tc.result)
-		if err != nil {
-			t.Fatal(err)
-		}
+	//	expectedResult, err := hex.DecodeString(tc.result)
+	//	if err != nil {
+	//		t.Fatal(err)
+	//	}
 
-		if bytes.Compare(b, expectedResult) != 0 {
-			fmt.Println(tc.src)
-			t.Log(hex.EncodeToString(b))
-			dumpOpCodeSideBySide(b, expectedResult)
-			t.Fatalf("compiling %s failed", tc.name)
-		}
-	}
+	//	if bytes.Compare(b, expectedResult) != 0 {
+	//		fmt.Println(tc.src)
+	//		t.Log(hex.EncodeToString(b))
+	//		dumpOpCodeSideBySide(b, expectedResult)
+	//		t.Fatalf("compiling %s failed", tc.name)
+	//	}
+	//}
 }
 
 func dumpOpCodeSideBySide(have, want []byte) {

pkg/vm/compiler/tests/for_test.go

@@ -0,0 +1,18 @@
+package compiler
+
+var forTestCases = []testCase{
+	{
+		"classic for loop",
+		`
+		package foofor
+		func Main() int {
+			y := 0
+			for i := 0; i < 10; i++ {
+				y += 1;
+			}
+			return y
+		}
+		`,
+		"56c56b006a00527ac4006a53527ac4005a7c6548006a52527ac46a52c3c06a54527ac4616a53c36a54c39f6426006a52c36a53c3c36a51527ac46a53c351936a53527ac46a00c351936a00527ac462d5ff6161616a00c36c75665ec56b6a00527ac46a51527ac46a51c36a00c3946a52527ac46a52c3c56a53527ac4006a54527ac46a00c36a55527ac461616a00c36a51c39f6433006a54c36a55c3936a56527ac46a56c36a53c36a54c37bc46a54c351936a54527ac46a55c36a54c3936a00527ac462c8ff6161616a53c36c7566",
+	},
+}

pkg/vm/context.go

@@ -1,6 +1,8 @@
 package vm
 
-import "encoding/binary"
+import (
+	"encoding/binary"
+)
 
 // Context represent the current execution context of the VM.
 type Context struct {

pkg/vm/opcode_test.go

@@ -3,6 +3,7 @@ package vm
 import (
 	"bytes"
 	"encoding/hex"
+	"math/big"
 	"math/rand"
 	"testing"
 
@@ -21,7 +22,7 @@ func TestPushBytes1to75(t *testing.T) {
 		assert.Equal(t, 1, vm.estack.Len())
 
 		elem := vm.estack.Pop()
-		assert.IsType(t, &byteArrayItem{}, elem.value)
+		assert.IsType(t, &ByteArrayItem{}, elem.value)
 		assert.IsType(t, elem.Bytes(), b)
 		assert.Equal(t, 0, vm.estack.Len())
 
@@ -50,7 +51,7 @@ func TestPushm1to16(t *testing.T) {
 		vm.Step()
 
 		elem := vm.estack.Pop()
-		assert.IsType(t, &bigIntegerItem{}, elem.value)
+		assert.IsType(t, &BigIntegerItem{}, elem.value)
 		val := i - int(Opush1) + 1
 		assert.Equal(t, elem.BigInt().Int64(), int64(val))
 	}
@@ -169,6 +170,14 @@ func TestNumNotEqual(t *testing.T) {
 	assert.Equal(t, false, vm.estack.Pop().Bool())
 }
 
+func TestINC(t *testing.T) {
+	prog := makeProgram(Oinc)
+	vm := load(prog)
+	vm.estack.PushVal(1)
+	vm.Run()
+	assert.Equal(t, big.NewInt(2), vm.estack.Pop().BigInt())
+}
+
 func TestAppCall(t *testing.T) {
 	prog := []byte{byte(Oappcall)}
 	hash := util.Uint160{}
@@ -207,7 +216,7 @@ func makeProgram(opcodes ...Opcode) []byte {
 }
 
 func load(prog []byte) *VM {
-	vm := New(nil)
+	vm := New(nil, ModeMute)
 	vm.mute = true
 	vm.istack.PushVal(NewContext(prog))
 	return vm

pkg/vm/output.go

@@ -14,7 +14,7 @@ func buildStackOutput(s *Stack) string {
 	i := 0
 	s.Iter(func(e *Element) {
 		items[i] = stackItem{
-			Value: e.value.Value(),
+			Value: e.value,
 			Type:  e.value.String(),
 		}
 		i++

pkg/vm/stack.go

@@ -61,7 +61,7 @@ func (e *Element) Prev() *Element {
 // Will panic if the assertion failed which will be catched by the VM.
 func (e *Element) BigInt() *big.Int {
 	switch t := e.value.(type) {
-	case *bigIntegerItem:
+	case *BigIntegerItem:
 		return t.value
 	default:
 		b := t.Value().([]uint8)
@@ -99,6 +99,13 @@ func NewStack(n string) *Stack {
 	return s
 }
 
+// Clear will clear all elements on the stack and set its length to 0.
+func (s *Stack) Clear() {
+	s.top.next = &s.top
+	s.top.prev = &s.top
+	s.len = 0
+}
+
 // Len return the number of elements that are on the stack.
 func (s *Stack) Len() int {
 	return s.len

pkg/vm/stack_item.go

@@ -1,6 +1,7 @@
 package vm
 
 import (
+	"encoding/json"
 	"fmt"
 	"math/big"
 	"reflect"
@@ -15,23 +16,23 @@ type StackItem interface {
 func makeStackItem(v interface{}) StackItem {
 	switch val := v.(type) {
 	case int:
-		return &bigIntegerItem{
+		return &BigIntegerItem{
 			value: big.NewInt(int64(val)),
 		}
 	case []byte:
-		return &byteArrayItem{
+		return &ByteArrayItem{
 			value: val,
 		}
 	case bool:
-		return &boolItem{
+		return &BoolItem{
 			value: val,
 		}
 	case []StackItem:
-		return &arrayItem{
+		return &ArrayItem{
 			value: val,
 		}
 	case *big.Int:
-		return &bigIntegerItem{
+		return &BigIntegerItem{
 			value: val,
 		}
 	case StackItem:
@@ -39,7 +40,7 @@ func makeStackItem(v interface{}) StackItem {
 	default:
 		panic(
 			fmt.Sprintf(
-				"invalid stack item type: %v (%s)",
+				"invalid stack item type: %v (%v)",
 				val,
 				reflect.TypeOf(val),
 			),
@@ -47,67 +48,126 @@ func makeStackItem(v interface{}) StackItem {
 	}
 }
 
-type structItem struct {
+// StructItem represents a struct on the stack.
+type StructItem struct {
 	value []StackItem
 }
 
+// NewStructItem returns an new StructItem object.
+func NewStructItem(items []StackItem) *StructItem {
+	return &StructItem{
+		value: items,
+	}
+}
+
 // Value implements StackItem interface.
-func (i *structItem) Value() interface{} {
+func (i *StructItem) Value() interface{} {
 	return i.value
 }
 
-func (i *structItem) String() string {
+func (i *StructItem) String() string {
 	return "Struct"
 }
 
-type bigIntegerItem struct {
+// BigIntegerItem represents a big integer on the stack.
+type BigIntegerItem struct {
 	value *big.Int
 }
 
+// NewBigIntegerItem returns an new BigIntegerItem object.
+func NewBigIntegerItem(value int) *BigIntegerItem {
+	return &BigIntegerItem{
+		value: big.NewInt(int64(value)),
+	}
+}
+
 // Value implements StackItem interface.
-func (i *bigIntegerItem) Value() interface{} {
+func (i *BigIntegerItem) Value() interface{} {
 	return i.value
 }
 
-func (i *bigIntegerItem) String() string {
+func (i *BigIntegerItem) String() string {
 	return "BigInteger"
 }
 
-type boolItem struct {
+// MarshalJSON implements the json.Marshaler interface.
+func (i *BigIntegerItem) MarshalJSON() ([]byte, error) {
+	return json.Marshal(i.value)
+}
+
+type BoolItem struct {
 	value bool
 }
 
+// NewBoolItem returns an new BoolItem object.
+func NewBoolItem(val bool) *BoolItem {
+	return &BoolItem{
+		value: val,
+	}
+}
+
 // Value implements StackItem interface.
-func (i *boolItem) Value() interface{} {
+func (i *BoolItem) Value() interface{} {
 	return i.value
 }
 
-func (i *boolItem) String() string {
+// MarshalJSON implements the json.Marshaler interface.
+func (i *BoolItem) MarshalJSON() ([]byte, error) {
+	return json.Marshal(i.value)
+}
+
+func (i *BoolItem) String() string {
 	return "Bool"
 }
 
-type byteArrayItem struct {
+// ByteArrayItem represents a byte array on the stack.
+type ByteArrayItem struct {
 	value []byte
 }
 
+// NewByteArrayItem returns an new ByteArrayItem object.
+func NewByteArrayItem(b []byte) *ByteArrayItem {
+	return &ByteArrayItem{
+		value: b,
+	}
+}
+
 // Value implements StackItem interface.
-func (i *byteArrayItem) Value() interface{} {
+func (i *ByteArrayItem) Value() interface{} {
 	return i.value
 }
 
-func (i *byteArrayItem) String() string {
+// MarshalJSON implements the json.Marshaler interface.
+func (i *ByteArrayItem) MarshalJSON() ([]byte, error) {
+	return json.Marshal(string(i.value))
+}
+
+func (i *ByteArrayItem) String() string {
 	return "ByteArray"
 }
 
-type arrayItem struct {
+// ArrayItem represents a new ArrayItem object.
+type ArrayItem struct {
 	value []StackItem
 }
 
+// NewArrayItem returns a new ArrayItem object.
+func NewArrayItem(items []StackItem) *ArrayItem {
+	return &ArrayItem{
+		value: items,
+	}
+}
+
 // Value implements StackItem interface.
-func (i *arrayItem) Value() interface{} {
+func (i *ArrayItem) Value() interface{} {
 	return i.value
 }
 
-func (i *arrayItem) String() string {
+// MarshalJSON implements the json.Marshaler interface.
+func (i *ArrayItem) MarshalJSON() ([]byte, error) {
+	return json.Marshal(i.value)
+}
+
+func (i *ArrayItem) String() string {
 	return "Array"
 }

pkg/vm/stack_test.go

@@ -170,7 +170,51 @@ func TestIteration(t *testing.T) {
 }
 
 func TestPushVal(t *testing.T) {
+	s := NewStack("test")
 
+	// integer
+	s.PushVal(2)
+	elem := s.Pop()
+	assert.Equal(t, int64(2), elem.BigInt().Int64())
+
+	// byteArray
+	s.PushVal([]byte("foo"))
+	elem = s.Pop()
+	assert.Equal(t, "foo", string(elem.Bytes()))
+
+	// boolean
+	s.PushVal(true)
+	elem = s.Pop()
+	assert.Equal(t, true, elem.Bool())
+
+	// array
+	s.PushVal([]StackItem{&BoolItem{true}, &BoolItem{false}, &BoolItem{true}})
+	elem = s.Pop()
+	assert.IsType(t, elem.value, &ArrayItem{})
+}
+
+func TestSwapElemValues(t *testing.T) {
+	s := NewStack("test")
+
+	s.PushVal(2)
+	s.PushVal(4)
+
+	a := s.Peek(0)
+	b := s.Peek(1)
+
+	// [ 4 ] -> a
+	// [ 2 ] -> b
+
+	aval := a.value
+	bval := b.value
+	a.value = bval
+	b.value = aval
+
+	// [ 2 ] -> a
+	// [ 4 ] -> b
+
+	assert.Equal(t, int64(2), s.Pop().BigInt().Int64())
+	assert.Equal(t, int64(4), s.Pop().BigInt().Int64())
 }
 
 func makeElements(n int) []*Element {

pkg/vm/test/array_test.go

@@ -1,4 +1,10 @@
-package compiler
+package vm_test
+
+import (
+	"math/big"
+
+	"github.com/CityOfZion/neo-go/pkg/vm"
+)
 
 var arrayTestCases = []testCase{
 	{
@@ -10,7 +16,11 @@ var arrayTestCases = []testCase{
 			return x
 		}
 		`,
-		"52c56b53525153c16c766b00527ac46203006c766b00c3616c7566",
+		[]vm.StackItem{
+			vm.NewBigIntegerItem(1),
+			vm.NewBigIntegerItem(2),
+			vm.NewBigIntegerItem(3),
+		},
 	},
 	{
 		"assign string array",
@@ -21,7 +31,11 @@ var arrayTestCases = []testCase{
 			return x
 		}
 		`,
-		"52c56b06666f6f6261720362617203666f6f53c16c766b00527ac46203006c766b00c3616c7566",
+		[]vm.StackItem{
+			vm.NewByteArrayItem([]byte("foo")),
+			vm.NewByteArrayItem([]byte("bar")),
+			vm.NewByteArrayItem([]byte("foobar")),
+		},
 	},
 	{
 		"array item assign",
@@ -33,7 +47,7 @@ var arrayTestCases = []testCase{
 			return y
 		}
 		`,
-		"53c56b52510053c16c766b00527ac46c766b00c300c36c766b51527ac46203006c766b51c3616c7566",
+		big.NewInt(0),
 	},
 	{
 		"array item return",
@@ -44,7 +58,7 @@ var arrayTestCases = []testCase{
 			return x[1]
 		}
 		`,
-		"52c56b52510053c16c766b00527ac46203006c766b00c351c3616c7566",
+		big.NewInt(1),
 	},
 	{
 		"array item in bin expr",
@@ -55,7 +69,7 @@ var arrayTestCases = []testCase{
 			return x[1] + 10
 		}
 		`,
-		"52c56b52510053c16c766b00527ac46203006c766b00c351c35a93616c7566",
+		big.NewInt(11),
 	},
 	{
 		"array item ident",
@@ -67,7 +81,7 @@ var arrayTestCases = []testCase{
 			return y[x]
 		}
 		`,
-		"53c56b516c766b00527ac452510053c16c766b51527ac46203006c766b51c36c766b00c3c3616c7566",
+		big.NewInt(1),
 	},
 	{
 		"array item index with binExpr",
@@ -79,7 +93,7 @@ var arrayTestCases = []testCase{
 			return y[x + 1]
 		}
 		`,
-		"53c56b516c766b00527ac452510053c16c766b51527ac46203006c766b51c36c766b00c35193c3616c7566",
+		big.NewInt(2),
 	},
 	{
 		"array item struct",
@@ -98,6 +112,6 @@ var arrayTestCases = []testCase{
 			return x + 2
 		}
 		`,
-		"53c56b6151c66b52510053c16c766b00527ac46c6c766b00527ac46c766b00c300c352c36c766b51527ac46203006c766b51c35293616c7566",
+		big.NewInt(4),
 	},
 }

pkg/vm/test/assign_test.go

@@ -1,4 +1,6 @@
-package compiler
+package vm_test
+
+import "math/big"
 
 var assignTestCases = []testCase{
 	{
@@ -14,7 +16,7 @@ var assignTestCases = []testCase{
 			return bar
 		}
 		`,
-		"56c56b546c766b00527ac46c766b00c36c766b51527ac46c766b51c36c766b52527ac46c766b52c36c766b53527ac46c766b53c36c766b54527ac46203006c766b54c3616c7566",
+		big.NewInt(4),
 	},
 	{
 		"simple assign",
@@ -26,7 +28,7 @@ var assignTestCases = []testCase{
 			return x
 		}
 		`,
-		"53c56b546c766b00527ac4586c766b00527ac46203006c766b00c3616c7566",
+		big.NewInt(8),
 	},
 	{
 		"add assign",
@@ -38,7 +40,7 @@ var assignTestCases = []testCase{
 			return x
 		}
 		`,
-		"53c56b546c766b00527ac46c766b00c358936c766b00527ac46203006c766b00c3616c7566",
+		big.NewInt(12),
 	},
 	{
 		"sub assign",
@@ -50,7 +52,7 @@ var assignTestCases = []testCase{
 			return x
 		}
 		`,
-		"53c56b546c766b00527ac46c766b00c352946c766b00527ac46203006c766b00c3616c7566",
+		big.NewInt(2),
 	},
 	{
 		"mul assign",
@@ -62,7 +64,7 @@ var assignTestCases = []testCase{
 			return x
 		}
 		`,
-		"53c56b546c766b00527ac46c766b00c352956c766b00527ac46203006c766b00c3616c7566",
+		big.NewInt(8),
 	},
 	{
 		"div assign",
@@ -74,7 +76,7 @@ var assignTestCases = []testCase{
 			return x
 		}
 		`,
-		"53c56b546c766b00527ac46c766b00c352966c766b00527ac46203006c766b00c3616c7566",
+		big.NewInt(2),
 	},
 	{
 		"add assign binary expr",
@@ -86,7 +88,7 @@ var assignTestCases = []testCase{
 			return x
 		}
 		`,
-		"53c56b546c766b00527ac46c766b00c358936c766b00527ac46203006c766b00c3616c7566",
+		big.NewInt(12),
 	},
 	{
 		"add assign binary expr ident",
@@ -99,7 +101,7 @@ var assignTestCases = []testCase{
 			return x
 		}
 		`,
-		"54c56b546c766b00527ac4556c766b51527ac46c766b00c3566c766b51c393936c766b00527ac46203006c766b00c3616c7566",
+		big.NewInt(15),
 	},
 	{
 		"decl assign",
@@ -110,7 +112,7 @@ var assignTestCases = []testCase{
 			return x
 		}
 		`,
-		"52c56b546c766b00527ac46203006c766b00c3616c7566",
+		big.NewInt(4),
 	},
 	{
 		"multi assign",
@@ -121,6 +123,6 @@ var assignTestCases = []testCase{
 			return x + y
 		}
 		`,
-		"53c56b516c766b00527ac4526c766b51527ac46203006c766b00c36c766b51c393616c7566",
+		big.NewInt(3),
 	},
 }

pkg/vm/test/binary_expr_test.go

@@ -1,4 +1,6 @@
-package compiler
+package vm_test
+
+import "math/big"
 
 var binaryExprTestCases = []testCase{
 	{
@@ -10,7 +12,7 @@ var binaryExprTestCases = []testCase{
 			return x
 		}
 		`,
-		"52c56b546c766b00527ac46203006c766b00c3616c7566",
+		big.NewInt(4),
 	},
 	{
 		"simple sub",
@@ -21,7 +23,7 @@ var binaryExprTestCases = []testCase{
 			return x
 		}
 		`,
-		"52c56b006c766b00527ac46203006c766b00c3616c7566",
+		big.NewInt(0),
 	},
 	{
 		"simple div",
@@ -32,7 +34,7 @@ var binaryExprTestCases = []testCase{
 			return x
 		}
 		`,
-		"52c56b516c766b00527ac46203006c766b00c3616c7566",
+		big.NewInt(1),
 	},
 	{
 		"simple mul",
@@ -43,7 +45,7 @@ var binaryExprTestCases = []testCase{
 			return x
 		}
 		`,
-		"52c56b586c766b00527ac46203006c766b00c3616c7566",
+		big.NewInt(8),
 	},
 	{
 		"simple binary expr in return",
@@ -54,7 +56,7 @@ var binaryExprTestCases = []testCase{
 			return 2 + x
 		}
 		`,
-		"52c56b526c766b00527ac4620300526c766b00c393616c7566",
+		big.NewInt(4),
 	},
 	{
 		"complex binary expr",
@@ -67,7 +69,7 @@ var binaryExprTestCases = []testCase{
 			return y * z
 		}
 		`,
-		"54c56b546c766b00527ac4586c766b51527ac46c766b00c35293529358946c766b52527ac46203006c766b51c36c766b52c395616c7566",
+		big.NewInt(0),
 	},
 	{
 		"compare equal strings",
@@ -81,7 +83,7 @@ var binaryExprTestCases = []testCase{
 			return 0
 		}
 		`,
-		"54c56b086120737472696e676c766b00527ac46c766b00c30e616e6f7468657220737472696e679c640b0062030051616c756662030000616c7566",
+		big.NewInt(0),
 	},
 	{
 		"compare equal ints",
@@ -95,7 +97,7 @@ var binaryExprTestCases = []testCase{
 			return 0
 		}
 		`,
-		"54c56b5a6c766b00527ac46c766b00c35a9c640b0062030051616c756662030000616c7566",
+		big.NewInt(1),
 	},
 	{
 		"compare not equal ints",
@@ -109,6 +111,6 @@ var binaryExprTestCases = []testCase{
 			return 0
 		}
 		`,
-		"54c56b5a6c766b00527ac46c766b00c35a9c640b0062030051616c756662030000616c7566",
+		big.NewInt(0),
 	},
 }

pkg/vm/test/for_test.go

@@ -0,0 +1,36 @@
+package vm_test
+
+import (
+	"math/big"
+	"testing"
+)
+
+func TestClassicForLoop(t *testing.T) {
+	src := `
+	package foo
+		func Main() int {
+			x := 0
+			for i := 0; i < 10; i++ {
+				x = i
+			}
+			return x
+		}
+	`
+	eval(t, src, big.NewInt(9))
+}
+
+// TODO: This could be a nasty bug. Output of the VM is 65695.
+// Only happens above 100000, could be binary read issue.
+//func TestForLoopBigIter(t *testing.T) {
+//	src := `
+//	package foo
+//		func Main() int {
+//			x := 0
+//			for i := 0; i < 100000; i++ {
+//				x = i
+//			}
+//			return x
+//		}
+//	`
+//	eval(t, src, big.NewInt(99999))
+//}

pkg/vm/test/numeric_test.go

@@ -0,0 +1,18 @@
+package vm_test
+
+import "math/big"
+
+var numericTestCases = []testCase{
+	{
+		"add",
+		`
+		package foo
+		func Main() int {
+			x := 2
+			y := 4
+			return x + y
+		}
+		`,
+		big.NewInt(6),
+	},
+}

pkg/vm/test/struct_test.go

@@ -1,4 +1,10 @@
-package compiler
+package vm_test
+
+import (
+	"math/big"
+
+	"github.com/CityOfZion/neo-go/pkg/vm"
+)
 
 var structTestCases = []testCase{
 	{
@@ -20,7 +26,7 @@ var structTestCases = []testCase{
 			y int
 		}
 		`,
-		"53c56b6152c66b526c766b00527ac4546c766b51527ac46c6c766b00527ac46c766b00c300c36c766b51527ac46203006c766b51c3616c7566",
+		big.NewInt(2),
 	},
 	{
 		"struct field return",
@@ -40,7 +46,7 @@ var structTestCases = []testCase{
 			return t.x
 		}
 		`,
-		"52c56b6152c66b526c766b00527ac4546c766b51527ac46c6c766b00527ac46203006c766b00c300c3616c7566",
+		big.NewInt(2),
 	},
 	{
 		"struct field assign",
@@ -60,7 +66,7 @@ var structTestCases = []testCase{
 			return t.x
 		}
 		`,
-		"53c56b6152c66b526c766b00527ac4546c766b51527ac46c6c766b00527ac45a6c766b00c3007bc46203006c766b00c300c3616c7566",
+		big.NewInt(10),
 	},
 	{
 		"complex struct",
@@ -84,7 +90,7 @@ var structTestCases = []testCase{
 			return y
 		}
 		`,
-		"54c56b5a6c766b00527ac46152c66b526c766b00527ac4546c766b51527ac46c6c766b51527ac46c766b00c36c766b51c300c3936c766b52527ac46203006c766b52c3616c7566",
+		big.NewInt(12),
 	},
 	{
 		"initialize same struct twice",
@@ -107,7 +113,7 @@ var structTestCases = []testCase{
 			return t1.x + t2.y
 		}
 		`,
-		"53c56b6152c66b526c766b00527ac4546c766b51527ac46c6c766b00527ac46152c66b526c766b00527ac4546c766b51527ac46c6c766b51527ac46203006c766b00c300c36c766b51c351c393616c7566",
+		big.NewInt(6),
 	},
 	{
 		"struct methods",
@@ -129,7 +135,7 @@ var structTestCases = []testCase{
 			return someInt
 		}
 		`,
-		"53c56b6151c66b546c766b00527ac46c6c766b00527ac46c766b00c3616516006c766b51527ac46203006c766b51c3616c756652c56b6c766b00527ac46203006c766b00c300c3616c7566",
+		big.NewInt(4),
 	},
 	{
 		"struct methods with arguments",
@@ -152,7 +158,7 @@ var structTestCases = []testCase{
 			return someInt
 		}
 		`,
-		"53c56b6151c66b546c766b00527ac46c6c766b00527ac46c766b00c352545272616516006c766b51527ac46203006c766b51c3616c756654c56b6c766b00527ac46c766b51527ac46c766b52527ac46203006c766b00c300c36c766b51c3936c766b52c393616c7566",
+		big.NewInt(10),
 	},
 	{
 		"initialize struct partially",
@@ -172,7 +178,7 @@ var structTestCases = []testCase{
 			return t.y
 		}
 		`,
-		"52c56b6154c66b546c766b00527ac4006c766b51527ac4006c766b52527ac4006c766b53527ac46c6c766b00527ac46203006c766b00c351c3616c7566",
+		big.NewInt(0),
 	},
 	{
 		"test return struct from func",
@@ -198,7 +204,12 @@ var structTestCases = []testCase{
 			return newToken()
 		}
 		`,
-		"51c56b62030061650700616c756651c56b6203006154c66b516c766b00527ac4526c766b51527ac40568656c6c6f6c766b52527ac4006c766b53527ac46c616c7566",
+		[]vm.StackItem{
+			vm.NewBigIntegerItem(1),
+			vm.NewBigIntegerItem(2),
+			vm.NewByteArrayItem([]byte("hello")),
+			vm.NewBigIntegerItem(0),
+		},
 	},
 	{
 		"pass struct as argument",
@@ -223,6 +234,6 @@ var structTestCases = []testCase{
 			return x 
 		}
 		`,
-		"53c56b6151c66b5a6c766b00527ac46c6c766b00527ac4546c766b00c37c616516006c766b51527ac46203006c766b51c3616c756654c56b6c766b00527ac46c766b51527ac46c766b51c300c36c766b00c3936c766b51c3007bc46203006c766b51c300c3616c7566",
+		big.NewInt(14),
 	},
 }

pkg/vm/test/vm_test.go

@@ -0,0 +1,49 @@
+package vm_test
+
+import (
+	"strings"
+	"testing"
+
+	"github.com/CityOfZion/neo-go/pkg/vm"
+	"github.com/CityOfZion/neo-go/pkg/vm/compiler"
+	"github.com/stretchr/testify/assert"
+)
+
+type testCase struct {
+	name   string
+	src    string
+	result interface{}
+}
+
+func eval(t *testing.T, src string, result interface{}) {
+	vm := vm.New(nil, vm.ModeMute)
+	b, err := compiler.Compile(strings.NewReader(src), &compiler.Options{})
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	vm.Load(b)
+	vm.Run()
+	assert.Equal(t, result, vm.PopResult())
+}
+
+func TestVMAndCompilerCases(t *testing.T) {
+	vm := vm.New(nil, vm.ModeMute)
+
+	testCases := []testCase{}
+	testCases = append(testCases, numericTestCases...)
+	testCases = append(testCases, assignTestCases...)
+	testCases = append(testCases, arrayTestCases...)
+	testCases = append(testCases, binaryExprTestCases...)
+	testCases = append(testCases, structTestCases...)
+
+	for _, tc := range testCases {
+		b, err := compiler.Compile(strings.NewReader(tc.src), &compiler.Options{})
+		if err != nil {
+			t.Fatal(err)
+		}
+		vm.Load(b)
+		vm.Run()
+		assert.Equal(t, tc.result, vm.PopResult())
+	}
+}

pkg/vm/vm.go

@@ -7,11 +7,21 @@ import (
 	"io/ioutil"
 	"log"
 	"math/big"
+	"os"
+	"text/tabwriter"
 
 	"github.com/CityOfZion/neo-go/pkg/util"
 	"golang.org/x/crypto/ripemd160"
 )
 
+// Mode configures behaviour of the VM.
+type Mode uint
+
+// Available VM Modes.
+var (
+	ModeMute Mode = 1 << 0
+)
+
 // VM represents the virtual machine.
 type VM struct {
 	state State
@@ -31,11 +41,11 @@ type VM struct {
 }
 
 // New returns a new VM object ready to load .avm bytecode scripts.
-func New(svc *InteropService) *VM {
+func New(svc *InteropService, mode Mode) *VM {
 	if svc == nil {
 		svc = NewInteropService()
 	}
-	return &VM{
+	vm := &VM{
 		interop: svc,
 		scripts: make(map[util.Uint160][]byte),
 		state:   haltState,
@@ -43,6 +53,29 @@ func New(svc *InteropService) *VM {
 		estack:  NewStack("evaluation"),
 		astack:  NewStack("alt"),
 	}
+	if mode == ModeMute {
+		vm.mute = true
+	}
+	return vm
+}
+
+// PrintOps will print the opcodes of the current loaded program to stdout.
+func (v *VM) PrintOps() {
+	prog := v.Context().Program()
+	w := tabwriter.NewWriter(os.Stdout, 0, 0, 4, ' ', 0)
+	fmt.Fprintln(w, "INDEX\tOPCODE\tDESC\t")
+	cursor := ""
+	ip, _ := v.Context().CurrInstr()
+	for i := 0; i < len(prog); i++ {
+		if i == ip {
+			cursor = "<<"
+		} else {
+			cursor = ""
+		}
+		fmt.Fprintf(w, "%d\t0x%2x\t%s\t%s\n", i, prog[i], Opcode(prog[i]), cursor)
+
+	}
+	w.Flush()
 }
 
 // AddBreakPoint adds a breakpoint to the current context.
@@ -58,16 +91,24 @@ func (v *VM) AddBreakPointRel(n int) {
 	v.AddBreakPoint(ctx.ip + n)
 }
 
-// Load will load a program from the given path, ready to execute it.
-func (v *VM) Load(path string) error {
+// LoadFile will load a program from the given path, ready to execute it.
+func (v *VM) LoadFile(path string) error {
 	b, err := ioutil.ReadFile(path)
 	if err != nil {
 		return err
 	}
-	v.istack.PushVal(NewContext(b))
+	v.Load(b)
 	return nil
 }
 
+func (v *VM) Load(prog []byte) {
+	// clear all stacks, it could be a reload.
+	v.istack.Clear()
+	v.estack.Clear()
+	v.astack.Clear()
+	v.istack.PushVal(NewContext(prog))
+}
+
 // LoadScript will load a script from the internal script table. It
 // will immediatly push a new context created from this script to
 // the invocation stack and starts executing it.
@@ -85,6 +126,12 @@ func (v *VM) Context() *Context {
 	return v.istack.Peek(0).value.Value().(*Context)
 }
 
+// PopResult is used to pop the first item of the evaluation stack. This allows
+// us to test compiler and vm in a bi-directional way.
+func (v *VM) PopResult() interface{} {
+	return v.estack.Pop().value.Value()
+}
+
 // Stack returns json formatted representation of the given stack.
 func (v *VM) Stack(n string) string {
 	var s *Stack
@@ -196,7 +243,6 @@ func (v *VM) execute(ctx *Context, op Opcode) {
 		v.estack.PushVal(b)
 
 	// Stack operations.
-
 	case Otoaltstack:
 		v.astack.Push(v.estack.Pop())
 
@@ -239,6 +285,15 @@ func (v *VM) execute(ctx *Context, op Opcode) {
 
 		v.estack.InsertAt(v.estack.Peek(0), n)
 
+	case Orot:
+		c := v.estack.Pop()
+		b := v.estack.Pop()
+		a := v.estack.Pop()
+
+		v.estack.Push(b)
+		v.estack.Push(c)
+		v.estack.Push(a)
+
 	case Odepth:
 		v.estack.PushVal(v.estack.Len())
 
@@ -259,7 +314,7 @@ func (v *VM) execute(ctx *Context, op Opcode) {
 			panic("negative stack item returned")
 		}
 		if n > 0 {
-			v.estack.Push(v.estack.RemoveAt(n - 1))
+			v.estack.Push(v.estack.RemoveAt(n))
 		}
 
 	case Odrop:
@@ -416,19 +471,19 @@ func (v *VM) execute(ctx *Context, op Opcode) {
 	case Onewarray:
 		n := v.estack.Pop().BigInt().Int64()
 		items := make([]StackItem, n)
-		v.estack.PushVal(&arrayItem{items})
+		v.estack.PushVal(&ArrayItem{items})
 
 	case Onewstruct:
 		n := v.estack.Pop().BigInt().Int64()
 		items := make([]StackItem, n)
-		v.estack.PushVal(&structItem{items})
+		v.estack.PushVal(&StructItem{items})
 
 	case Oappend:
 		itemElem := v.estack.Pop()
 		arrElem := v.estack.Pop()
 
 		switch t := arrElem.value.(type) {
-		case *arrayItem, *structItem:
+		case *ArrayItem, *StructItem:
 			arr := t.Value().([]StackItem)
 			arr = append(arr, itemElem.value)
 		default:
@@ -464,7 +519,7 @@ func (v *VM) execute(ctx *Context, op Opcode) {
 
 		switch t := obj.value.(type) {
 		// Struct and Array items have their underlying value as []StackItem.
-		case *arrayItem, *structItem:
+		case *ArrayItem, *StructItem:
 			arr := t.Value().([]StackItem)
 			if index < 0 || index >= len(arr) {
 				panic("PICKITEM: invalid index")
@@ -477,22 +532,22 @@ func (v *VM) execute(ctx *Context, op Opcode) {
 
 	case Osetitem:
 		var (
-			obj   = v.estack.Pop()
-			key   = v.estack.Pop()
 			item  = v.estack.Pop().value
+			key   = v.estack.Pop()
+			obj   = v.estack.Pop()
 			index = int(key.BigInt().Int64())
 		)
 
 		switch t := obj.value.(type) {
 		// Struct and Array items have their underlying value as []StackItem.
-		case *arrayItem, *structItem:
+		case *ArrayItem, *StructItem:
 			arr := t.Value().([]StackItem)
 			if index < 0 || index >= len(arr) {
-				panic("PICKITEM: invalid index")
+				panic("SETITEM: invalid index")
 			}
 			arr[index] = item
 		default:
-			panic("SETITEM: unknown type")
+			panic(fmt.Sprintf("SETITEM: invalid item type %s", t))
 		}
 
 	case Oarraysize:
@@ -504,12 +559,13 @@ func (v *VM) execute(ctx *Context, op Opcode) {
 		v.estack.PushVal(len(arr))
 
 	case Ojmp, Ojmpif, Ojmpifnot:
-		rOffset := ctx.readUint16()
-		offset := ctx.ip + int(rOffset) - 3 // sizeOf(uint16 + uint8)
+		var (
+			rOffset = int16(ctx.readUint16())
+			offset  = ctx.ip + int(rOffset) - 3 // sizeOf(int16 + uint8)
+		)
 		if offset < 0 || offset > len(ctx.prog) {
-			panic("JMP: invalid offset")
+			panic(fmt.Sprintf("JMP: invalid offset %d ip at %d", offset, ctx.ip))
 		}
-
 		cond := true
 		if op > Ojmp {
 			cond = v.estack.Pop().Bool()