From 9081211f122a182d20cd3d95bcfe2db06ec3d6e8 Mon Sep 17 00:00:00 2001
From: Evgenii Stratonikov <evgeniy@nspcc.ru>
Date: Thu, 30 Apr 2020 10:52:29 +0300
Subject: [PATCH] vm: implement NOTEQUAL opcode

---
 pkg/compiler/codegen.go |  3 +--
 pkg/vm/opcode/opcode.go | 11 ++++++-----
 pkg/vm/vm.go            |  4 ++--
 pkg/vm/vm_test.go       | 18 ++++++++++++++++++
 4 files changed, 27 insertions(+), 9 deletions(-)

diff --git a/pkg/compiler/codegen.go b/pkg/compiler/codegen.go
index 3ddcb1ecc..d91cdf759 100644
--- a/pkg/compiler/codegen.go
+++ b/pkg/compiler/codegen.go
@@ -616,8 +616,7 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 			case n.Op == token.NEQ:
 				// VM has separate opcodes for number and string equality
 				if isStringType(c.typeInfo.Types[n.X].Type) {
-					emit.Opcode(c.prog.BinWriter, opcode.EQUAL)
-					emit.Opcode(c.prog.BinWriter, opcode.NOT)
+					emit.Opcode(c.prog.BinWriter, opcode.NOTEQUAL)
 				} else {
 					emit.Opcode(c.prog.BinWriter, opcode.NUMNOTEQUAL)
 				}
diff --git a/pkg/vm/opcode/opcode.go b/pkg/vm/opcode/opcode.go
index cb453c7b0..071317cdf 100644
--- a/pkg/vm/opcode/opcode.go
+++ b/pkg/vm/opcode/opcode.go
@@ -98,11 +98,12 @@ const (
 	RIGHT  Opcode = 0x81
 
 	// Bitwise logic
-	INVERT Opcode = 0x90
-	AND    Opcode = 0x91
-	OR     Opcode = 0x92
-	XOR    Opcode = 0x93
-	EQUAL  Opcode = 0x97
+	INVERT   Opcode = 0x90
+	AND      Opcode = 0x91
+	OR       Opcode = 0x92
+	XOR      Opcode = 0x93
+	EQUAL    Opcode = 0x97
+	NOTEQUAL Opcode = 0x98
 
 	// Arithmetic
 	SIGN        Opcode = 0x99
diff --git a/pkg/vm/vm.go b/pkg/vm/vm.go
index 721dd3247..b11bfb876 100644
--- a/pkg/vm/vm.go
+++ b/pkg/vm/vm.go
@@ -748,7 +748,7 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 		a := v.estack.Pop().BigInt()
 		v.estack.PushVal(new(big.Int).Xor(b, a))
 
-	case opcode.EQUAL:
+	case opcode.EQUAL, opcode.NOTEQUAL:
 		b := v.estack.Pop()
 		if b == nil {
 			panic("no top-level element found")
@@ -757,7 +757,7 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 		if a == nil {
 			panic("no second-to-the-top element found")
 		}
-		v.estack.PushVal(a.value.Equals(b.value))
+		v.estack.PushVal(a.value.Equals(b.value) == (op == opcode.EQUAL))
 
 	// Numeric operations.
 	case opcode.SIGN:
diff --git a/pkg/vm/vm_test.go b/pkg/vm/vm_test.go
index a5922cdfa..ff50a24d2 100644
--- a/pkg/vm/vm_test.go
+++ b/pkg/vm/vm_test.go
@@ -1319,6 +1319,24 @@ func TestEQUALMapFalse(t *testing.T) {
 	assert.Equal(t, &BoolItem{false}, vm.estack.Pop().value)
 }
 
+func getTestFuncForVM(prog []byte, result interface{}, args ...interface{}) func(t *testing.T) {
+	return func(t *testing.T) {
+		v := load(prog)
+		for i := range args {
+			v.estack.PushVal(args[i])
+		}
+		runVM(t, v)
+		require.Equal(t, 1, v.estack.Len())
+		require.Equal(t, makeStackItem(result), v.estack.Pop().value)
+	}
+}
+
+func TestNOTEQUALByteArray(t *testing.T) {
+	prog := makeProgram(opcode.NOTEQUAL)
+	t.Run("True", getTestFuncForVM(prog, true, []byte{1, 2}, []byte{0, 1, 2}))
+	t.Run("False", getTestFuncForVM(prog, false, []byte{1, 2}, []byte{1, 2}))
+}
+
 func TestNumEqual(t *testing.T) {
 	prog := makeProgram(opcode.NUMEQUAL)
 	vm := load(prog)