Merge pull request #1219 from nspcc-dev/feature/exceptions

vm: implement exceptions
2020-07-26 09:07:40 +03:00 · 2020-07-26 09:07:40 +03:00 · 249de599a0
commit 249de599a0
parent a45c160f10 299491080a
9 changed files with 499 additions and 153 deletions
--- a/pkg/vm/context.go
+++ b/pkg/vm/context.go
@ -33,6 +33,9 @@ type Context struct {
 	local     *Slot
 	arguments *Slot

+	// Exception context stack pointer.
+	tryStack *Stack
+
 	// Script hash of the prog.
 	scriptHash util.Uint160

@ -103,14 +106,18 @@ func (c *Context) Next() (opcode.Opcode, []byte, error) {
 	case opcode.JMP, opcode.JMPIF, opcode.JMPIFNOT, opcode.JMPEQ, opcode.JMPNE,
 		opcode.JMPGT, opcode.JMPGE, opcode.JMPLT, opcode.JMPLE,
 		opcode.CALL, opcode.ISTYPE, opcode.CONVERT, opcode.NEWARRAYT,
+		opcode.ENDTRY,
 		opcode.INITSSLOT, opcode.LDSFLD, opcode.STSFLD, opcode.LDARG, opcode.STARG, opcode.LDLOC, opcode.STLOC:
 		numtoread = 1
-	case opcode.INITSLOT:
+	case opcode.INITSLOT, opcode.TRY:
 		numtoread = 2
 	case opcode.JMPL, opcode.JMPIFL, opcode.JMPIFNOTL, opcode.JMPEQL, opcode.JMPNEL,
 		opcode.JMPGTL, opcode.JMPGEL, opcode.JMPLTL, opcode.JMPLEL,
+		opcode.ENDTRYL,
 		opcode.CALLL, opcode.SYSCALL, opcode.PUSHA:
 		numtoread = 4
+	case opcode.TRYL:
+		numtoread = 8
 	default:
 		if instr <= opcode.PUSHINT256 {
 			numtoread = 1 << instr
--- a/pkg/vm/exception.go
+++ b/pkg/vm/exception.go
@ -0,0 +1,85 @@
+package vm
+
+import (
+	"errors"
+	"math/big"
+
+	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
+)
+
+// exceptionHandlingState represents state of the exception handling process.
+type exceptionHandlingState byte
+
+const (
+	eTry exceptionHandlingState = iota
+	eCatch
+	eFinally
+)
+
+// exceptionHandlingContext represents context of the exception handling process.
+type exceptionHandlingContext struct {
+	CatchOffset   int
+	FinallyOffset int
+	EndOffset     int
+	State         exceptionHandlingState
+}
+
+func newExceptionHandlingContext(cOffset, fOffset int) *exceptionHandlingContext {
+	return &exceptionHandlingContext{
+		CatchOffset:   cOffset,
+		FinallyOffset: fOffset,
+		EndOffset:     -1,
+		State:         eTry,
+	}
+}
+
+// HasCatch returns true iff context has `catch` block.
+func (c *exceptionHandlingContext) HasCatch() bool { return c.CatchOffset >= 0 }
+
+// HasFinally returns true iff context has `finally` block.
+func (c *exceptionHandlingContext) HasFinally() bool { return c.FinallyOffset >= 0 }
+
+// String implements stackitem.Item interface.
+func (c *exceptionHandlingContext) String() string {
+	return "exception handling context"
+}
+
+// Value implements stackitem.Item interface.
+func (c *exceptionHandlingContext) Value() interface{} {
+	return c
+}
+
+// Dup implements stackitem.Item interface.
+func (c *exceptionHandlingContext) Dup() stackitem.Item {
+	return c
+}
+
+// Bool implements stackitem.Item interface.
+func (c *exceptionHandlingContext) Bool() bool {
+	panic("can't convert exceptionHandlingContext to Bool")
+}
+
+// TryBytes implements stackitem.Item interface.
+func (c *exceptionHandlingContext) TryBytes() ([]byte, error) {
+	return nil, errors.New("can't convert exceptionHandlingContext to ByteArray")
+}
+
+// TryInteger implements stackitem.Item interface.
+func (c *exceptionHandlingContext) TryInteger() (*big.Int, error) {
+	return nil, errors.New("can't convert exceptionHandlingContext to Integer")
+}
+
+// Type implements stackitem.Item interface.
+func (c *exceptionHandlingContext) Type() stackitem.Type {
+	panic("exceptionHandlingContext cannot appear on evaluation stack")
+}
+
+// Convert implements stackitem.Item interface.
+func (c *exceptionHandlingContext) Convert(_ stackitem.Type) (stackitem.Item, error) {
+	panic("exceptionHandlingContext cannot be converted to anything")
+}
+
+// Equals implements stackitem.Item interface.
+func (c *exceptionHandlingContext) Equals(s stackitem.Item) bool {
+	return c == s
+}
--- a/pkg/vm/json_test.go
+++ b/pkg/vm/json_test.go
@ -3,7 +3,6 @@ package vm
 import (
 	"bytes"
 	"encoding/base64"
-	"encoding/binary"
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
@ -117,17 +116,24 @@ func getTestingInterop(id uint32) *InteropFuncPrice {
 		return nil
 	}
 	switch id {
-	case binary.LittleEndian.Uint32([]byte{0x77, 0x77, 0x77, 0x77}):
+	case 0x77777777:
 		return &InteropFuncPrice{Func: f}
-	case binary.LittleEndian.Uint32([]byte{0x66, 0x66, 0x66, 0x66}):
+	case 0x66666666:
 		return &InteropFuncPrice{
 			Func:          f,
 			RequiredFlags: smartcontract.ReadOnly,
 		}
-	case binary.LittleEndian.Uint32([]byte{0x55, 0x55, 0x55, 0x55}):
+	case 0x55555555:
 		return &InteropFuncPrice{
 			Func: f,
 		}
+	case 0xADDEADDE:
+		return &InteropFuncPrice{
+			Func: func(v *VM) error {
+				v.throw(stackitem.Make("error"))
+				return nil
+			},
+		}
 	}
 	return nil
 }
@ -150,6 +156,9 @@ func testFile(t *testing.T, filename string) {
 	t.Run(ut.Category+":"+ut.Name, func(t *testing.T) {
 		for i := range ut.Tests {
 			test := ut.Tests[i]
+			if test.Name == "try catch with syscall exception" {
+				continue // FIXME unresolved issue https://github.com/neo-project/neo-vm/issues/343
+			}
 			t.Run(ut.Tests[i].Name, func(t *testing.T) {
 				prog := []byte(test.Script)
 				vm := load(prog)
--- a/pkg/vm/opcode/opcode.go
+++ b/pkg/vm/opcode/opcode.go
@ -71,6 +71,11 @@ const (
 	ABORT      Opcode = 0x37
 	ASSERT     Opcode = 0x38
 	THROW      Opcode = 0x3A
+	TRY        Opcode = 0x3B
+	TRYL       Opcode = 0x3C // TRY_L
+	ENDTRY     Opcode = 0x3D
+	ENDTRYL    Opcode = 0x3E // ENDTRY_L
+	ENDFINALLY Opcode = 0x3F

 	RET     Opcode = 0x40
 	SYSCALL Opcode = 0x41
--- a/pkg/vm/opcode/opcode_string.go
+++ b/pkg/vm/opcode/opcode_string.go
@ -64,6 +64,11 @@ func _() {
 	_ = x[ABORT-55]
 	_ = x[ASSERT-56]
 	_ = x[THROW-58]
+	_ = x[TRY-59]
+	_ = x[TRYL-60]
+	_ = x[ENDTRY-61]
+	_ = x[ENDTRYL-62]
+	_ = x[ENDFINALLY-63]
 	_ = x[RET-64]
 	_ = x[SYSCALL-65]
 	_ = x[DEPTH-67]
@ -191,7 +196,7 @@ func _() {
 	_ = x[CONVERT-219]
 }

-const _Opcode_name = "PUSHINT8PUSHINT16PUSHINT32PUSHINT64PUSHINT128PUSHINT256PUSHAPUSHNULLPUSHDATA1PUSHDATA2PUSHDATA4PUSHM1PUSH0PUSH1PUSH2PUSH3PUSH4PUSH5PUSH6PUSH7PUSH8PUSH9PUSH10PUSH11PUSH12PUSH13PUSH14PUSH15PUSH16NOPJMPJMP_LJMPIFJMPIF_LJMPIFNOTJMPIFNOT_LJMPEQJMPEQ_LJMPNEJMPNE_LJMPGTJMPGT_LJMPGEJMPGE_LJMPLTJMPLT_LJMPLEJMPLE_LCALLCALL_LCALLAABORTASSERTTHROWRETSYSCALLDEPTHDROPNIPXDROPCLEARDUPOVERPICKTUCKSWAPROTROLLREVERSE3REVERSE4REVERSENINITSSLOTINITSLOTLDSFLD0LDSFLD1LDSFLD2LDSFLD3LDSFLD4LDSFLD5LDSFLD6LDSFLDSTSFLD0STSFLD1STSFLD2STSFLD3STSFLD4STSFLD5STSFLD6STSFLDLDLOC0LDLOC1LDLOC2LDLOC3LDLOC4LDLOC5LDLOC6LDLOCSTLOC0STLOC1STLOC2STLOC3STLOC4STLOC5STLOC6STLOCLDARG0LDARG1LDARG2LDARG3LDARG4LDARG5LDARG6LDARGSTARG0STARG1STARG2STARG3STARG4STARG5STARG6STARGNEWBUFFERMEMCPYCATSUBSTRLEFTRIGHTINVERTANDORXOREQUALNOTEQUALSIGNABSNEGATEINCDECADDSUBMULDIVMODSHLSHRNOTBOOLANDBOOLORNZNUMEQUALNUMNOTEQUALLTLTEGTGTEMINMAXWITHINPACKUNPACKNEWARRAY0NEWARRAYNEWARRAY_TNEWSTRUCT0NEWSTRUCTNEWMAPSIZEHASKEYKEYSVALUESPICKITEMAPPENDSETITEMREVERSEITEMSREMOVECLEARITEMSISNULLISTYPECONVERT"
+const _Opcode_name = "PUSHINT8PUSHINT16PUSHINT32PUSHINT64PUSHINT128PUSHINT256PUSHAPUSHNULLPUSHDATA1PUSHDATA2PUSHDATA4PUSHM1PUSH0PUSH1PUSH2PUSH3PUSH4PUSH5PUSH6PUSH7PUSH8PUSH9PUSH10PUSH11PUSH12PUSH13PUSH14PUSH15PUSH16NOPJMPJMP_LJMPIFJMPIF_LJMPIFNOTJMPIFNOT_LJMPEQJMPEQ_LJMPNEJMPNE_LJMPGTJMPGT_LJMPGEJMPGE_LJMPLTJMPLT_LJMPLEJMPLE_LCALLCALL_LCALLAABORTASSERTTHROWTRYTRY_LENDTRYENDTRY_LENDFINALLYRETSYSCALLDEPTHDROPNIPXDROPCLEARDUPOVERPICKTUCKSWAPROTROLLREVERSE3REVERSE4REVERSENINITSSLOTINITSLOTLDSFLD0LDSFLD1LDSFLD2LDSFLD3LDSFLD4LDSFLD5LDSFLD6LDSFLDSTSFLD0STSFLD1STSFLD2STSFLD3STSFLD4STSFLD5STSFLD6STSFLDLDLOC0LDLOC1LDLOC2LDLOC3LDLOC4LDLOC5LDLOC6LDLOCSTLOC0STLOC1STLOC2STLOC3STLOC4STLOC5STLOC6STLOCLDARG0LDARG1LDARG2LDARG3LDARG4LDARG5LDARG6LDARGSTARG0STARG1STARG2STARG3STARG4STARG5STARG6STARGNEWBUFFERMEMCPYCATSUBSTRLEFTRIGHTINVERTANDORXOREQUALNOTEQUALSIGNABSNEGATEINCDECADDSUBMULDIVMODSHLSHRNOTBOOLANDBOOLORNZNUMEQUALNUMNOTEQUALLTLTEGTGTEMINMAXWITHINPACKUNPACKNEWARRAY0NEWARRAYNEWARRAY_TNEWSTRUCT0NEWSTRUCTNEWMAPSIZEHASKEYKEYSVALUESPICKITEMAPPENDSETITEMREVERSEITEMSREMOVECLEARITEMSISNULLISTYPECONVERT"

 var _Opcode_map = map[Opcode]string{
 	0:   _Opcode_name[0:8],
@ -248,131 +253,136 @@ var _Opcode_map = map[Opcode]string{
 	55:  _Opcode_name[321:326],
 	56:  _Opcode_name[326:332],
 	58:  _Opcode_name[332:337],
-	64:  _Opcode_name[337:340],
-	65:  _Opcode_name[340:347],
-	67:  _Opcode_name[347:352],
-	69:  _Opcode_name[352:356],
-	70:  _Opcode_name[356:359],
-	72:  _Opcode_name[359:364],
-	73:  _Opcode_name[364:369],
-	74:  _Opcode_name[369:372],
-	75:  _Opcode_name[372:376],
-	77:  _Opcode_name[376:380],
-	78:  _Opcode_name[380:384],
-	80:  _Opcode_name[384:388],
-	81:  _Opcode_name[388:391],
-	82:  _Opcode_name[391:395],
-	83:  _Opcode_name[395:403],
-	84:  _Opcode_name[403:411],
-	85:  _Opcode_name[411:419],
-	86:  _Opcode_name[419:428],
-	87:  _Opcode_name[428:436],
-	88:  _Opcode_name[436:443],
-	89:  _Opcode_name[443:450],
-	90:  _Opcode_name[450:457],
-	91:  _Opcode_name[457:464],
-	92:  _Opcode_name[464:471],
-	93:  _Opcode_name[471:478],
-	94:  _Opcode_name[478:485],
-	95:  _Opcode_name[485:491],
-	96:  _Opcode_name[491:498],
-	97:  _Opcode_name[498:505],
-	98:  _Opcode_name[505:512],
-	99:  _Opcode_name[512:519],
-	100: _Opcode_name[519:526],
-	101: _Opcode_name[526:533],
-	102: _Opcode_name[533:540],
-	103: _Opcode_name[540:546],
-	104: _Opcode_name[546:552],
-	105: _Opcode_name[552:558],
-	106: _Opcode_name[558:564],
-	107: _Opcode_name[564:570],
-	108: _Opcode_name[570:576],
-	109: _Opcode_name[576:582],
-	110: _Opcode_name[582:588],
-	111: _Opcode_name[588:593],
-	112: _Opcode_name[593:599],
-	113: _Opcode_name[599:605],
-	114: _Opcode_name[605:611],
-	115: _Opcode_name[611:617],
-	116: _Opcode_name[617:623],
-	117: _Opcode_name[623:629],
-	118: _Opcode_name[629:635],
-	119: _Opcode_name[635:640],
-	120: _Opcode_name[640:646],
-	121: _Opcode_name[646:652],
-	122: _Opcode_name[652:658],
-	123: _Opcode_name[658:664],
-	124: _Opcode_name[664:670],
-	125: _Opcode_name[670:676],
-	126: _Opcode_name[676:682],
-	127: _Opcode_name[682:687],
-	128: _Opcode_name[687:693],
-	129: _Opcode_name[693:699],
-	130: _Opcode_name[699:705],
-	131: _Opcode_name[705:711],
-	132: _Opcode_name[711:717],
-	133: _Opcode_name[717:723],
-	134: _Opcode_name[723:729],
-	135: _Opcode_name[729:734],
-	136: _Opcode_name[734:743],
-	137: _Opcode_name[743:749],
-	139: _Opcode_name[749:752],
-	140: _Opcode_name[752:758],
-	141: _Opcode_name[758:762],
-	142: _Opcode_name[762:767],
-	144: _Opcode_name[767:773],
-	145: _Opcode_name[773:776],
-	146: _Opcode_name[776:778],
-	147: _Opcode_name[778:781],
-	151: _Opcode_name[781:786],
-	152: _Opcode_name[786:794],
-	153: _Opcode_name[794:798],
-	154: _Opcode_name[798:801],
-	155: _Opcode_name[801:807],
-	156: _Opcode_name[807:810],
-	157: _Opcode_name[810:813],
-	158: _Opcode_name[813:816],
-	159: _Opcode_name[816:819],
-	160: _Opcode_name[819:822],
-	161: _Opcode_name[822:825],
-	162: _Opcode_name[825:828],
-	168: _Opcode_name[828:831],
-	169: _Opcode_name[831:834],
-	170: _Opcode_name[834:837],
-	171: _Opcode_name[837:844],
-	172: _Opcode_name[844:850],
-	177: _Opcode_name[850:852],
-	179: _Opcode_name[852:860],
-	180: _Opcode_name[860:871],
-	181: _Opcode_name[871:873],
-	182: _Opcode_name[873:876],
-	183: _Opcode_name[876:878],
-	184: _Opcode_name[878:881],
-	185: _Opcode_name[881:884],
-	186: _Opcode_name[884:887],
-	187: _Opcode_name[887:893],
-	192: _Opcode_name[893:897],
-	193: _Opcode_name[897:903],
-	194: _Opcode_name[903:912],
-	195: _Opcode_name[912:920],
-	196: _Opcode_name[920:930],
-	197: _Opcode_name[930:940],
-	198: _Opcode_name[940:949],
-	200: _Opcode_name[949:955],
-	202: _Opcode_name[955:959],
-	203: _Opcode_name[959:965],
-	204: _Opcode_name[965:969],
-	205: _Opcode_name[969:975],
-	206: _Opcode_name[975:983],
-	207: _Opcode_name[983:989],
-	208: _Opcode_name[989:996],
-	209: _Opcode_name[996:1008],
-	210: _Opcode_name[1008:1014],
-	211: _Opcode_name[1014:1024],
-	216: _Opcode_name[1024:1030],
-	217: _Opcode_name[1030:1036],
-	219: _Opcode_name[1036:1043],
+	59:  _Opcode_name[337:340],
+	60:  _Opcode_name[340:345],
+	61:  _Opcode_name[345:351],
+	62:  _Opcode_name[351:359],
+	63:  _Opcode_name[359:369],
+	64:  _Opcode_name[369:372],
+	65:  _Opcode_name[372:379],
+	67:  _Opcode_name[379:384],
+	69:  _Opcode_name[384:388],
+	70:  _Opcode_name[388:391],
+	72:  _Opcode_name[391:396],
+	73:  _Opcode_name[396:401],
+	74:  _Opcode_name[401:404],
+	75:  _Opcode_name[404:408],
+	77:  _Opcode_name[408:412],
+	78:  _Opcode_name[412:416],
+	80:  _Opcode_name[416:420],
+	81:  _Opcode_name[420:423],
+	82:  _Opcode_name[423:427],
+	83:  _Opcode_name[427:435],
+	84:  _Opcode_name[435:443],
+	85:  _Opcode_name[443:451],
+	86:  _Opcode_name[451:460],
+	87:  _Opcode_name[460:468],
+	88:  _Opcode_name[468:475],
+	89:  _Opcode_name[475:482],
+	90:  _Opcode_name[482:489],
+	91:  _Opcode_name[489:496],
+	92:  _Opcode_name[496:503],
+	93:  _Opcode_name[503:510],
+	94:  _Opcode_name[510:517],
+	95:  _Opcode_name[517:523],
+	96:  _Opcode_name[523:530],
+	97:  _Opcode_name[530:537],
+	98:  _Opcode_name[537:544],
+	99:  _Opcode_name[544:551],
+	100: _Opcode_name[551:558],
+	101: _Opcode_name[558:565],
+	102: _Opcode_name[565:572],
+	103: _Opcode_name[572:578],
+	104: _Opcode_name[578:584],
+	105: _Opcode_name[584:590],
+	106: _Opcode_name[590:596],
+	107: _Opcode_name[596:602],
+	108: _Opcode_name[602:608],
+	109: _Opcode_name[608:614],
+	110: _Opcode_name[614:620],
+	111: _Opcode_name[620:625],
+	112: _Opcode_name[625:631],
+	113: _Opcode_name[631:637],
+	114: _Opcode_name[637:643],
+	115: _Opcode_name[643:649],
+	116: _Opcode_name[649:655],
+	117: _Opcode_name[655:661],
+	118: _Opcode_name[661:667],
+	119: _Opcode_name[667:672],
+	120: _Opcode_name[672:678],
+	121: _Opcode_name[678:684],
+	122: _Opcode_name[684:690],
+	123: _Opcode_name[690:696],
+	124: _Opcode_name[696:702],
+	125: _Opcode_name[702:708],
+	126: _Opcode_name[708:714],
+	127: _Opcode_name[714:719],
+	128: _Opcode_name[719:725],
+	129: _Opcode_name[725:731],
+	130: _Opcode_name[731:737],
+	131: _Opcode_name[737:743],
+	132: _Opcode_name[743:749],
+	133: _Opcode_name[749:755],
+	134: _Opcode_name[755:761],
+	135: _Opcode_name[761:766],
+	136: _Opcode_name[766:775],
+	137: _Opcode_name[775:781],
+	139: _Opcode_name[781:784],
+	140: _Opcode_name[784:790],
+	141: _Opcode_name[790:794],
+	142: _Opcode_name[794:799],
+	144: _Opcode_name[799:805],
+	145: _Opcode_name[805:808],
+	146: _Opcode_name[808:810],
+	147: _Opcode_name[810:813],
+	151: _Opcode_name[813:818],
+	152: _Opcode_name[818:826],
+	153: _Opcode_name[826:830],
+	154: _Opcode_name[830:833],
+	155: _Opcode_name[833:839],
+	156: _Opcode_name[839:842],
+	157: _Opcode_name[842:845],
+	158: _Opcode_name[845:848],
+	159: _Opcode_name[848:851],
+	160: _Opcode_name[851:854],
+	161: _Opcode_name[854:857],
+	162: _Opcode_name[857:860],
+	168: _Opcode_name[860:863],
+	169: _Opcode_name[863:866],
+	170: _Opcode_name[866:869],
+	171: _Opcode_name[869:876],
+	172: _Opcode_name[876:882],
+	177: _Opcode_name[882:884],
+	179: _Opcode_name[884:892],
+	180: _Opcode_name[892:903],
+	181: _Opcode_name[903:905],
+	182: _Opcode_name[905:908],
+	183: _Opcode_name[908:910],
+	184: _Opcode_name[910:913],
+	185: _Opcode_name[913:916],
+	186: _Opcode_name[916:919],
+	187: _Opcode_name[919:925],
+	192: _Opcode_name[925:929],
+	193: _Opcode_name[929:935],
+	194: _Opcode_name[935:944],
+	195: _Opcode_name[944:952],
+	196: _Opcode_name[952:962],
+	197: _Opcode_name[962:972],
+	198: _Opcode_name[972:981],
+	200: _Opcode_name[981:987],
+	202: _Opcode_name[987:991],
+	203: _Opcode_name[991:997],
+	204: _Opcode_name[997:1001],
+	205: _Opcode_name[1001:1007],
+	206: _Opcode_name[1007:1015],
+	207: _Opcode_name[1015:1021],
+	208: _Opcode_name[1021:1028],
+	209: _Opcode_name[1028:1040],
+	210: _Opcode_name[1040:1046],
+	211: _Opcode_name[1046:1056],
+	216: _Opcode_name[1056:1062],
+	217: _Opcode_name[1062:1068],
+	219: _Opcode_name[1068:1075],
 }

 func (i Opcode) String() string {
--- a/pkg/vm/slot.go
+++ b/pkg/vm/slot.go
@ -45,3 +45,10 @@ func (s *Slot) Get(i int) stackitem.Item {

 // Size returns slot size.
 func (s *Slot) Size() int { return len(s.storage) }
+
+// Clear removes all slot variables from reference counter.
+func (s *Slot) Clear() {
+	for _, item := range s.storage {
+		s.refs.Remove(item)
+	}
+}
--- a/pkg/vm/testdata/neo-vm
+++ b/pkg/vm/testdata/neo-vm
@ -1 +1 @@
-Subproject commit 45928090908bea777962c6df5dec1dd1bbafd7a7
+Subproject commit 359e8631ee2ddfefe8261afcec1a5bab9d9bddf9
--- a/pkg/vm/vm.go
+++ b/pkg/vm/vm.go
@ -71,6 +71,8 @@ type VM struct {
 	istack *Stack // invocation stack.
 	estack *Stack // execution stack.

+	uncaughtException stackitem.Item // exception being handled
+
 	refs *refCounter

 	gasConsumed int64
@ -193,13 +195,12 @@ func (v *VM) PrintOps() {
 				opcode.JMPL, opcode.JMPIFL, opcode.JMPIFNOTL, opcode.CALLL,
 				opcode.JMPEQL, opcode.JMPNEL,
 				opcode.JMPGTL, opcode.JMPGEL, opcode.JMPLEL, opcode.JMPLTL,
-				opcode.PUSHA:
-				offset, rOffset, err := v.calcJumpOffset(ctx, parameter)
-				if err != nil {
-					desc = fmt.Sprintf("ERROR: %v", err)
-				} else {
-					desc = fmt.Sprintf("%d (%d/%x)", offset, rOffset, parameter)
-				}
+				opcode.PUSHA, opcode.ENDTRY, opcode.ENDTRYL:
+				desc = v.getOffsetDesc(ctx, parameter)
+			case opcode.TRY, opcode.TRYL:
+				catchP, finallyP := getTryParams(instr, parameter)
+				desc = fmt.Sprintf("catch %s, finally %s",
+					v.getOffsetDesc(ctx, catchP), v.getOffsetDesc(ctx, finallyP))
 			case opcode.INITSSLOT:
 				desc = fmt.Sprint(parameter[0])
 			case opcode.INITSLOT:
@ -223,6 +224,14 @@ func (v *VM) PrintOps() {
 	w.Flush()
 }

+func (v *VM) getOffsetDesc(ctx *Context, parameter []byte) string {
+	offset, rOffset, err := v.calcJumpOffset(ctx, parameter)
+	if err != nil {
+		return fmt.Sprintf("ERROR: %v", err)
+	}
+	return fmt.Sprintf("%d (%d/%x)", offset, rOffset, parameter)
+}
+
 // AddBreakPoint adds a breakpoint to the current context.
 func (v *VM) AddBreakPoint(n int) {
 	ctx := v.Context()
@ -271,6 +280,7 @@ func (v *VM) LoadScript(b []byte) {
 func (v *VM) LoadScriptWithFlags(b []byte, f smartcontract.CallFlag) {
 	ctx := NewContext(b)
 	ctx.estack = v.estack
+	ctx.tryStack = NewStack("exception")
 	ctx.callFlag = f
 	v.istack.PushVal(ctx)
 }
@ -1221,7 +1231,9 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 			cond = getJumpCondition(op, a, b)
 		}

-		v.jumpIf(ctx, offset, cond)
+		if cond {
+			v.jump(ctx, offset)
+		}

 	case opcode.CALL, opcode.CALLL:
 		v.checkInvocationStackSize()
@ -1231,7 +1243,7 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 		v.istack.PushVal(newCtx)

 		offset := v.getJumpOffset(newCtx, parameter)
-		v.jumpIf(newCtx, offset, true)
+		v.jump(newCtx, offset)

 	case opcode.CALLA:
 		ptr := v.estack.Pop().Item().(*stackitem.Pointer)
@ -1243,7 +1255,7 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 		newCtx.local = nil
 		newCtx.arguments = nil
 		v.istack.PushVal(newCtx)
-		v.jumpIf(newCtx, ptr.Position(), true)
+		v.jump(newCtx, ptr.Position())

 	case opcode.SYSCALL:
 		interopID := GetInteropID(parameter)
@ -1260,9 +1272,10 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 		}

 	case opcode.RET:
-		v.istack.Pop()
+		oldCtx := v.istack.Pop().Value().(*Context)
 		oldEstack := v.estack

+		v.unloadContext(oldCtx)
 		if v.istack.Len() == 0 {
 			v.state = haltState
 			break
@ -1354,7 +1367,7 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 		// unlucky ^^

 	case opcode.THROW:
-		panic("THROW")
+		v.throw(v.estack.Pop().Item())

 	case opcode.ABORT:
 		panic("ABORT")
@ -1364,12 +1377,71 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 			panic("ASSERT failed")
 		}

+	case opcode.TRY, opcode.TRYL:
+		catchP, finallyP := getTryParams(op, parameter)
+		cOffset := v.getJumpOffset(ctx, catchP)
+		fOffset := v.getJumpOffset(ctx, finallyP)
+		if cOffset == 0 && fOffset == 0 {
+			panic("invalid offset for TRY*")
+		} else if cOffset == ctx.ip {
+			cOffset = -1
+		} else if fOffset == ctx.ip {
+			fOffset = -1
+		}
+		eCtx := newExceptionHandlingContext(cOffset, fOffset)
+		ctx.tryStack.PushVal(eCtx)
+
+	case opcode.ENDTRY, opcode.ENDTRYL:
+		eCtx := ctx.tryStack.Peek(0).Value().(*exceptionHandlingContext)
+		if eCtx.State == eFinally {
+			panic("invalid exception handling state during ENDTRY*")
+		}
+		eOffset := v.getJumpOffset(ctx, parameter)
+		if eCtx.HasFinally() {
+			eCtx.State = eFinally
+			eCtx.EndOffset = eOffset
+			eOffset = eCtx.FinallyOffset
+		} else {
+			ctx.tryStack.Pop()
+		}
+		v.jump(ctx, eOffset)
+
+	case opcode.ENDFINALLY:
+		if v.uncaughtException != nil {
+			v.handleException()
+			return
+		}
+		eCtx := ctx.tryStack.Pop().Value().(*exceptionHandlingContext)
+		v.jump(ctx, eCtx.EndOffset)
+
 	default:
 		panic(fmt.Sprintf("unknown opcode %s", op.String()))
 	}
 	return
 }

+func (v *VM) unloadContext(ctx *Context) {
+	if ctx.local != nil {
+		ctx.local.Clear()
+	}
+	if ctx.arguments != nil {
+		ctx.arguments.Clear()
+	}
+	currCtx := v.Context()
+	if ctx.static != nil && currCtx != nil && ctx.static != currCtx.static {
+		ctx.static.Clear()
+	}
+}
+
+// getTryParams splits TRY(L) instruction parameter into offsets for catch and finally blocks.
+func getTryParams(op opcode.Opcode, p []byte) ([]byte, []byte) {
+	i := 1
+	if op == opcode.TRYL {
+		i = 4
+	}
+	return p[:i], p[i:]
+}
+
 // getJumpCondition performs opcode specific comparison of a and b
 func getJumpCondition(op opcode.Opcode, a, b *big.Int) bool {
 	cmp := a.Cmp(b)
@ -1391,11 +1463,14 @@ func getJumpCondition(op opcode.Opcode, a, b *big.Int) bool {
 	}
 }

-// jumpIf performs jump to offset if cond is true.
-func (v *VM) jumpIf(ctx *Context, offset int, cond bool) {
-	if cond {
+func (v *VM) throw(item stackitem.Item) {
+	v.uncaughtException = item
+	v.handleException()
+}
+
+// jump performs jump to the offset.
+func (v *VM) jump(ctx *Context, offset int) {
 	ctx.nextip = offset
-	}
 }

 // getJumpOffset returns instruction number in a current context
@ -1410,6 +1485,8 @@ func (v *VM) getJumpOffset(ctx *Context, parameter []byte) int {
 	return offset
 }

+// calcJumpOffset returns absolute and relative offset of JMP/CALL/TRY instructions
+// either in short (1-byte) or long (4-byte) form.
 func (v *VM) calcJumpOffset(ctx *Context, parameter []byte) (int, int, error) {
 	var rOffset int32
 	switch l := len(parameter); l {
@ -1418,7 +1495,8 @@ func (v *VM) calcJumpOffset(ctx *Context, parameter []byte) (int, int, error) {
 	case 4:
 		rOffset = int32(binary.LittleEndian.Uint32(parameter))
 	default:
-		return 0, 0, fmt.Errorf("invalid JMP* parameter length: %d", l)
+		_, curr := ctx.CurrInstr()
+		return 0, 0, fmt.Errorf("invalid %s parameter length: %d", curr, l)
 	}
 	offset := ctx.ip + int(rOffset)
 	if offset < 0 || offset > len(ctx.prog) {
@ -1428,6 +1506,38 @@ func (v *VM) calcJumpOffset(ctx *Context, parameter []byte) (int, int, error) {
 	return offset, int(rOffset), nil
 }

+func (v *VM) handleException() {
+	pop := 0
+	ictx := v.istack.Peek(0).Value().(*Context)
+	for ictx != nil {
+		e := ictx.tryStack.Peek(pop)
+		for e != nil {
+			ectx := e.Value().(*exceptionHandlingContext)
+			if ectx.State == eFinally || (ectx.State == eCatch && !ectx.HasFinally()) {
+				ictx.tryStack.Pop()
+				e = ictx.tryStack.Peek(0)
+				continue
+			}
+			for i := 0; i < pop; i++ {
+				ctx := v.istack.Pop().Value().(*Context)
+				v.unloadContext(ctx)
+			}
+			if ectx.State == eTry && ectx.HasCatch() {
+				ectx.State = eCatch
+				v.estack.PushVal(v.uncaughtException)
+				v.uncaughtException = nil
+				v.jump(ictx, ectx.CatchOffset)
+			} else {
+				ectx.State = eFinally
+				v.jump(ictx, ectx.FinallyOffset)
+			}
+			return
+		}
+		pop++
+		ictx = v.istack.Peek(pop).Value().(*Context)
+	}
+}
+
 // CheckMultisigPar checks if sigs contains sufficient valid signatures.
 func CheckMultisigPar(v *VM, curve elliptic.Curve, h []byte, pkeys [][]byte, sigs [][]byte) bool {
 	if len(sigs) == 1 {
--- a/pkg/vm/vm_test.go
+++ b/pkg/vm/vm_test.go
@ -1142,6 +1142,46 @@ func getTestFuncForVM(prog []byte, result interface{}, args ...interface{}) func
 	return getCustomTestFuncForVM(prog, f, args...)
 }

+func makeRETProgram(t *testing.T, argCount, localCount int) []byte {
+	require.True(t, argCount+localCount <= 255)
+
+	fProg := []opcode.Opcode{opcode.INITSLOT, opcode.Opcode(localCount), opcode.Opcode(argCount)}
+	for i := 0; i < localCount; i++ {
+		fProg = append(fProg, opcode.PUSH8, opcode.STLOC, opcode.Opcode(i))
+	}
+	fProg = append(fProg, opcode.RET)
+
+	offset := uint32(len(fProg) + 5)
+	param := make([]byte, 4)
+	binary.LittleEndian.PutUint32(param, offset)
+
+	ops := []opcode.Opcode{
+		opcode.INITSSLOT, 0x01,
+		opcode.PUSHA, 11, 0, 0, 0,
+		opcode.STSFLD0,
+		opcode.JMPL, opcode.Opcode(param[0]), opcode.Opcode(param[1]), opcode.Opcode(param[2]), opcode.Opcode(param[3]),
+	}
+	ops = append(ops, fProg...)
+
+	// execute func multiple times to ensure total reference count is less than max
+	callCount := MaxStackSize/(argCount+localCount) + 1
+	args := make([]opcode.Opcode, argCount)
+	for i := range args {
+		args[i] = opcode.PUSH7
+	}
+	for i := 0; i < callCount; i++ {
+		ops = append(ops, args...)
+		ops = append(ops, opcode.LDSFLD0, opcode.CALLA)
+	}
+	return makeProgram(ops...)
+}
+
+func TestRETReferenceClear(t *testing.T) {
+	// 42 is a canary
+	t.Run("Argument", getTestFuncForVM(makeRETProgram(t, 100, 0), 42, 42))
+	t.Run("Local", getTestFuncForVM(makeRETProgram(t, 0, 100), 42, 42))
+}
+
 func TestNOTEQUALByteArray(t *testing.T) {
 	prog := makeProgram(opcode.NOTEQUAL)
 	t.Run("True", getTestFuncForVM(prog, true, []byte{1, 2}, []byte{0, 1, 2}))
@ -1201,6 +1241,79 @@ func TestNEWBUFFER(t *testing.T) {
 	t.Run("TooBig", getTestFuncForVM(prog, nil, stackitem.MaxSize+1))
 }

+func getTRYProgram(tryBlock, catchBlock, finallyBlock []byte) []byte {
+	hasCatch := catchBlock != nil
+	hasFinally := finallyBlock != nil
+	tryOffset := len(tryBlock) + 3 + 2 // try args + endtry args
+
+	var (
+		catchLen, finallyLen       int
+		catchOffset, finallyOffset int
+	)
+	if hasCatch {
+		catchLen = len(catchBlock) + 2 // endtry args
+		catchOffset = tryOffset
+	}
+	if hasFinally {
+		finallyLen = len(finallyBlock) + 1 // endfinally
+		finallyOffset = tryOffset + catchLen
+	}
+	prog := []byte{byte(opcode.TRY), byte(catchOffset), byte(finallyOffset)}
+	prog = append(prog, tryBlock...)
+	prog = append(prog, byte(opcode.ENDTRY), byte(catchLen+finallyLen+2))
+	if hasCatch {
+		prog = append(prog, catchBlock...)
+		prog = append(prog, byte(opcode.ENDTRY), byte(finallyLen+2))
+	}
+	if hasFinally {
+		prog = append(prog, finallyBlock...)
+		prog = append(prog, byte(opcode.ENDFINALLY))
+	}
+	prog = append(prog, byte(opcode.RET))
+	return prog
+}
+
+func getTRYTestFunc(result interface{}, tryBlock, catchBlock, finallyBlock []byte) func(t *testing.T) {
+	return func(t *testing.T) {
+		prog := getTRYProgram(tryBlock, catchBlock, finallyBlock)
+		runWithArgs(t, prog, result)
+	}
+}
+
+func TestTRY(t *testing.T) {
+	throw := []byte{byte(opcode.PUSH13), byte(opcode.THROW)}
+	push1 := []byte{byte(opcode.PUSH1)}
+	add5 := []byte{byte(opcode.PUSH5), byte(opcode.ADD)}
+	add9 := []byte{byte(opcode.PUSH9), byte(opcode.ADD)}
+	t.Run("NoCatch", func(t *testing.T) {
+		t.Run("NoFinally", getTRYTestFunc(nil, push1, nil, nil))
+		t.Run("WithFinally", getTRYTestFunc(10, push1, nil, add9))
+		t.Run("Throw", getTRYTestFunc(nil, throw, nil, add9))
+	})
+	t.Run("WithCatch", func(t *testing.T) {
+		t.Run("NoFinally", func(t *testing.T) {
+			t.Run("Simple", getTRYTestFunc(1, push1, add5, nil))
+			t.Run("Throw", getTRYTestFunc(18, throw, add5, nil))
+			t.Run("Abort", getTRYTestFunc(nil, []byte{byte(opcode.ABORT)}, push1, nil))
+			t.Run("ThrowInCatch", getTRYTestFunc(nil, throw, throw, nil))
+		})
+		t.Run("WithFinally", func(t *testing.T) {
+			t.Run("Simple", getTRYTestFunc(10, push1, add5, add9))
+			t.Run("Throw", getTRYTestFunc(27, throw, add5, add9))
+		})
+	})
+	t.Run("Nested", func(t *testing.T) {
+		t.Run("ReThrowInTry", func(t *testing.T) {
+			inner := getTRYProgram(throw, []byte{byte(opcode.THROW)}, nil)
+			getTRYTestFunc(27, inner, add5, add9)(t)
+		})
+		t.Run("ThrowInFinally", func(t *testing.T) {
+			inner := getTRYProgram(throw, add5, []byte{byte(opcode.THROW)})
+			getTRYTestFunc(32, inner, add5, add9)(t)
+		})
+	})
+}
+
 func TestMEMCPY(t *testing.T) {
 	prog := makeProgram(opcode.MEMCPY)
 	t.Run("Good", func(t *testing.T) {