Merge pull request #1939 from nspcc-dev/vm-arith-null

Allow NULL items for LT/LE/GT/GE instructions

Author: roman-khimov

pkg/compiler/codegen.go

@@ -1901,11 +1901,11 @@ func convertToken(tok token.Token, typ types.Type) (opcode.Opcode, error) {
 	case token.LSS:
 		return opcode.LT, nil
 	case token.LEQ:
-		return opcode.LTE, nil
+		return opcode.LE, nil
 	case token.GTR:
 		return opcode.GT, nil
 	case token.GEQ:
-		return opcode.GTE, nil
+		return opcode.GE, nil
 	case token.EQL:
 		// VM has separate opcodes for number and string equality
 		if isNumber(typ) {

pkg/core/fee/opcode.go

@@ -173,9 +173,9 @@ var coefficients = map[opcode.Opcode]int64{
 	opcode.NUMEQUAL:     1 << 3,
 	opcode.NUMNOTEQUAL:  1 << 3,
 	opcode.LT:           1 << 3,
-	opcode.LTE:          1 << 3,
+	opcode.LE:           1 << 3,
 	opcode.GT:           1 << 3,
-	opcode.GTE:          1 << 3,
+	opcode.GE:           1 << 3,
 	opcode.MIN:          1 << 3,
 	opcode.MAX:          1 << 3,
 	opcode.WITHIN:       1 << 3,

pkg/vm/opcode/opcode.go

@@ -188,9 +188,9 @@ const (
 	NUMEQUAL    Opcode = 0xB3
 	NUMNOTEQUAL Opcode = 0xB4
 	LT          Opcode = 0xB5
-	LTE         Opcode = 0xB6
+	LE          Opcode = 0xB6
 	GT          Opcode = 0xB7
-	GTE         Opcode = 0xB8
+	GE          Opcode = 0xB8
 	MIN         Opcode = 0xB9
 	MAX         Opcode = 0xBA
 	WITHIN      Opcode = 0xBB

pkg/vm/opcode/opcode_string.go

@@ -571,7 +571,7 @@ func BenchmarkOpcodes(t *testing.B) {
 	}
 	binaries := []opcode.Opcode{opcode.AND, opcode.OR, opcode.XOR, opcode.ADD, opcode.SUB,
 		opcode.BOOLAND, opcode.BOOLOR, opcode.NUMEQUAL, opcode.NUMNOTEQUAL,
-		opcode.LT, opcode.LTE, opcode.GT, opcode.GTE, opcode.MIN, opcode.MAX}
+		opcode.LT, opcode.LE, opcode.GT, opcode.GE, opcode.MIN, opcode.MAX}
 	for _, op := range binaries {
 		t.Run(op.String(), func(t *testing.B) {
 			t.Run("0+0", func(t *testing.B) { benchOpcode(t, opParamPushVM(op, nil, 0, 0)) })

pkg/vm/opcodebench_test.go

@@ -972,25 +972,27 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 		a := v.estack.Pop().BigInt()
 		v.estack.PushVal(a.Cmp(b) != 0)
 
-	case opcode.LT:
-		b := v.estack.Pop().BigInt()
-		a := v.estack.Pop().BigInt()
-		v.estack.PushVal(a.Cmp(b) == -1)
-
-	case opcode.LTE:
-		b := v.estack.Pop().BigInt()
-		a := v.estack.Pop().BigInt()
-		v.estack.PushVal(a.Cmp(b) <= 0)
-
-	case opcode.GT:
-		b := v.estack.Pop().BigInt()
-		a := v.estack.Pop().BigInt()
-		v.estack.PushVal(a.Cmp(b) == 1)
-
-	case opcode.GTE:
-		b := v.estack.Pop().BigInt()
-		a := v.estack.Pop().BigInt()
-		v.estack.PushVal(a.Cmp(b) >= 0)
+	case opcode.LT, opcode.LE, opcode.GT, opcode.GE:
+		eb := v.estack.Pop()
+		ea := v.estack.Pop()
+		_, aNil := ea.Item().(stackitem.Null)
+		_, bNil := eb.Item().(stackitem.Null)
+
+		res := !aNil && !bNil
+		if res {
+			cmp := ea.BigInt().Cmp(eb.BigInt())
+			switch op {
+			case opcode.LT:
+				res = cmp == -1
+			case opcode.LE:
+				res = cmp <= 0
+			case opcode.GT:
+				res = cmp == 1
+			case opcode.GE:
+				res = cmp >= 0
+			}
+		}
+		v.estack.PushVal(res)
 
 	case opcode.MIN:
 		b := v.estack.Pop().BigInt()

pkg/vm/testdata/neo-vm

@@ -807,13 +807,25 @@ func TestSHL(t *testing.T) {
 	t.Run("BigResult", getTestFuncForVM(prog, nil, getBigInt(stackitem.MaxBigIntegerSizeBits/2, 0), stackitem.MaxBigIntegerSizeBits/2))
 }
 
+func TestArithNullArg(t *testing.T) {
+	for _, op := range []opcode.Opcode{opcode.LT, opcode.LE, opcode.GT, opcode.GE} {
+		prog := makeProgram(op)
+		t.Run(op.String(), func(t *testing.T) {
+			runWithArgs(t, prog, false, stackitem.Null{}, 0)
+			runWithArgs(t, prog, false, 0, stackitem.Null{})
+			runWithArgs(t, prog, nil, stackitem.NewInterop(nil), 1) // also has `.Value() == nil`
+		})
+
+	}
+}
+
 func TestLT(t *testing.T) {
 	prog := makeProgram(opcode.LT)
 	runWithArgs(t, prog, false, 4, 3)
 }
 
-func TestLTE(t *testing.T) {
-	prog := makeProgram(opcode.LTE)
+func TestLE(t *testing.T) {
+	prog := makeProgram(opcode.LE)
 	runWithArgs(t, prog, true, 2, 3)
 }
 
@@ -822,8 +834,8 @@ func TestGT(t *testing.T) {
 	runWithArgs(t, prog, true, 9, 3)
 }
 
-func TestGTE(t *testing.T) {
-	prog := makeProgram(opcode.GTE)
+func TestGE(t *testing.T) {
+	prog := makeProgram(opcode.GE)
 	runWithArgs(t, prog, true, 3, 3)
 }