Merge pull request #1222 from nspcc-dev/fix/rvcount

Remove return value count

pkg/compiler/vm_test.go

@@ -51,7 +51,6 @@ func evalWithArgs(t *testing.T, src string, op []byte, args []stackitem.Item, re
 
 func assertResult(t *testing.T, vm *vm.VM, result interface{}) {
 	assert.Equal(t, result, vm.PopResult())
-	assert.Equal(t, 0, vm.Astack().Len())
 	assert.Equal(t, 0, vm.Istack().Len())
 }
 

pkg/vm/context.go

@@ -26,15 +26,9 @@ type Context struct {
 	// Breakpoints.
 	breakPoints []int
 
-	// Return value count, -1 is unspecified.
-	rvcount int
-
 	// Evaluation stack pointer.
 	estack *Stack
 
-	// Alt stack pointer.
-	astack *Stack
-
 	static    *Slot
 	local     *Slot
 	arguments *Slot
@@ -56,7 +50,6 @@ func NewContext(b []byte) *Context {
 	return &Context{
 		prog:        b,
 		breakPoints: []int{},
-		rvcount:     -1,
 	}
 }
 

pkg/vm/vm.go

@@ -70,7 +70,6 @@ type VM struct {
 
 	istack *Stack // invocation stack.
 	estack *Stack // execution stack.
-	astack *Stack // alt stack.
 
 	refs *refCounter
 
@@ -100,7 +99,6 @@ func NewWithTrigger(t trigger.Type) *VM {
 	}
 
 	vm.estack = vm.newItemStack("evaluation")
-	vm.astack = vm.newItemStack("alt")
 
 	vm.RegisterInteropGetter(getDefaultVMInterop)
 	return vm
@@ -142,11 +140,6 @@ func (v *VM) Estack() *Stack {
 	return v.estack
 }
 
-// Astack returns the alt stack so interop hooks can utilize this.
-func (v *VM) Astack() *Stack {
-	return v.astack
-}
-
 // Istack returns the invocation stack so interop hooks can utilize this.
 func (v *VM) Istack() *Stack {
 	return v.istack
@@ -264,7 +257,6 @@ func (v *VM) Load(prog []byte) {
 	// Clear all stacks and state, it could be a reload.
 	v.istack.Clear()
 	v.estack.Clear()
-	v.astack.Clear()
 	v.state = noneState
 	v.gasConsumed = 0
 	v.LoadScript(prog)
@@ -281,7 +273,6 @@ func (v *VM) LoadScript(b []byte) {
 func (v *VM) LoadScriptWithFlags(b []byte, f smartcontract.CallFlag) {
 	ctx := NewContext(b)
 	ctx.estack = v.estack
-	ctx.astack = v.astack
 	ctx.callFlag = f
 	v.istack.PushVal(ctx)
 }
@@ -319,9 +310,6 @@ func (v *VM) PopResult() interface{} {
 // Stack returns json formatted representation of the given stack.
 func (v *VM) Stack(n string) string {
 	var s *Stack
-	if n == "astack" {
-		s = v.astack
-	}
 	if n == "istack" {
 		s = v.istack
 	}
@@ -1245,7 +1233,6 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 		newCtx := ctx.Copy()
 		newCtx.local = nil
 		newCtx.arguments = nil
-		newCtx.rvcount = -1
 		v.istack.PushVal(newCtx)
 
 		offset := v.getJumpOffset(newCtx, parameter)
@@ -1260,7 +1247,6 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 		newCtx := ctx.Copy()
 		newCtx.local = nil
 		newCtx.arguments = nil
-		newCtx.rvcount = -1
 		v.istack.PushVal(newCtx)
 		v.jumpIf(newCtx, ptr.Position(), true)
 
@@ -1282,13 +1268,9 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 		}
 
 	case opcode.RET:
-		oldCtx := v.istack.Pop().Value().(*Context)
+		v.istack.Pop()
-		rvcount := oldCtx.rvcount
 		oldEstack := v.estack
 
-		if rvcount > 0 && oldEstack.Len() < rvcount {
-			panic("missing some return elements")
-		}
 		if v.istack.Len() == 0 {
 			v.state = haltState
 			break
@@ -1296,15 +1278,12 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 
 		newEstack := v.Context().estack
 		if oldEstack != newEstack {
-			if rvcount < 0 {
+			rvcount := oldEstack.Len()
-				rvcount = oldEstack.Len()
-			}
 			for i := rvcount; i > 0; i-- {
 				elem := oldEstack.RemoveAt(i - 1)
 				newEstack.Push(elem)
 			}
 			v.estack = newEstack
-			v.astack = v.Context().astack
 		}
 
 	case opcode.NEWMAP:

pkg/vm/vm_test.go

@@ -149,7 +149,6 @@ func TestPushBytes1to75(t *testing.T) {
 		errExec := vm.execute(nil, opcode.RET, nil)
 		require.NoError(t, errExec)
 
-		assert.Equal(t, 0, vm.astack.Len())
 		assert.Equal(t, 0, vm.istack.Len())
 		buf.Reset()
 	}