vm: leave single CHECKMULTISIG implementation

Remove sequential implementation and benchmarks.
They will be still present in commit history.

pkg/vm/vm.go

@@ -84,8 +84,6 @@ type VM struct {
 
 	// Public keys cache.
 	keys map[string]*keys.PublicKey
-
-	checkMultisig func(*VM, [][]byte, [][]byte) bool
 }
 
 // New returns a new VM object ready to load .avm bytecode scripts.
@@ -1223,13 +1221,7 @@ func (v *VM) execute(ctx *Context, op opcode.Opcode, parameter []byte) (err erro
 			panic("VM is not set up properly for signature checks")
 		}
 
-		var sigok bool
+		sigok := checkMultisigPar(v, pkeys, sigs)
-		if v.checkMultisig == nil {
-			sigok = checkMultisigPar(v, pkeys, sigs)
-		} else {
-			sigok = v.checkMultisig(v, pkeys, sigs)
-		}
-
 		v.estack.PushVal(sigok)
 
 	case opcode.NEWMAP:
@@ -1523,30 +1515,6 @@ func checkMultisig1(v *VM, pkeys [][]byte, sig []byte) bool {
 	return false
 }
 
-func checkMultisigSeq(v *VM, pkeys [][]byte, sigs [][]byte) bool {
-	// j counts keys and i counts signatures.
-	j := 0
-	for i := 0; j < len(pkeys) && i < len(sigs); {
-		pkey := v.bytesToPublicKey(pkeys[j])
-
-		// We only move to the next signature if the check was
-		// successful, but if it's not maybe the next key will
-		// fit, so we always move to the next key.
-		if pkey.Verify(sigs[i], v.checkhash) {
-			i++
-		}
-		j++
-
-		// When there are more signatures left to check than
-		// there are keys the check won't successed for sure.
-		if len(sigs)-i > len(pkeys)-j {
-			return false
-		}
-	}
-
-	return true
-}
-
 func cloneIfStruct(item StackItem) StackItem {
 	switch it := item.(type) {
 	case *StructItem:

pkg/vm/vm_test.go

@@ -2790,99 +2790,6 @@ func TestCHECKMULTISIGBad(t *testing.T) {
 	t.Run("3_2 duplicate sig", func(t *testing.T) { testCHECKMULTISIGBad(t, 3, nil, []int{0, 0}) })
 }
 
-func benchCHECKMULTISIG(b *testing.B, size int, is [][]int, check func(*VM, [][]byte, [][]byte) bool) {
-	prog := makeProgram(opcode.CHECKMULTISIG)
-	msg := []byte("NEO - An Open Network For Smart Economy")
-	h := hash.Sha256(msg).BytesBE()
-
-	pubs, sigs, keyMap, err := initCHECKMULTISIG(msg, size)
-	if err != nil {
-		b.Fatalf("error on initialize: %v", err)
-	}
-
-	sigsStack := make([][]StackItem, 0, len(is))
-	for i := range is {
-		sigsStack = append(sigsStack, subSlice(sigs, is[i]))
-	}
-
-	b.ResetTimer()
-	b.ReportAllocs()
-	for i := 0; i < b.N; i++ {
-		for j := range sigsStack {
-			vm := load(prog)
-			vm.SetCheckedHash(h)
-			vm.SetPublicKeys(keyMap)
-			vm.checkMultisig = check
-			vm.estack.PushVal(sigsStack[j])
-			vm.estack.PushVal(pubs)
-			_ = vm.Run()
-		}
-	}
-}
-
-func BenchmarkCHECKMULTISIG(b *testing.B) {
-	fs := []struct {
-		name string
-		f    func(*VM, [][]byte, [][]byte) bool
-	}{
-		{"seq", checkMultisigSeq},
-		{"par", checkMultisigPar},
-	}
-
-	b.Run("4_3 start", func(b *testing.B) {
-		for i := range fs {
-			b.Run(fs[i].name, func(b *testing.B) {
-				benchCHECKMULTISIG(b, 4, [][]int{{0, 1, 2}}, fs[i].f)
-			})
-		}
-	})
-
-	b.Run("4_3 all", func(b *testing.B) {
-		for i := range fs {
-			b.Run(fs[i].name, func(b *testing.B) {
-				benchCHECKMULTISIG(b, 4, combinations(4, 3), fs[i].f)
-			})
-		}
-	})
-
-	b.Run("7_5 start", func(b *testing.B) {
-		for i := range fs {
-			b.Run(fs[i].name, func(b *testing.B) {
-				benchCHECKMULTISIG(b, 7, [][]int{{0, 1, 2, 3, 4}}, fs[i].f)
-			})
-		}
-	})
-
-	b.Run("7_5 all", func(b *testing.B) {
-		for i := range fs {
-			b.Run(fs[i].name, func(b *testing.B) {
-				benchCHECKMULTISIG(b, 7, combinations(7, 5), fs[i].f)
-			})
-		}
-	})
-}
-
-func combinations(n, k int) [][]int {
-	if n < k {
-		return nil
-	} else if k == 0 {
-		return [][]int{{}}
-	} else if n == k {
-		res := make([]int, k)
-		for i := 0; i < k; i++ {
-			res[i] = i
-		}
-		return [][]int{res}
-	}
-
-	result := combinations(n-1, k)
-	for _, c := range combinations(n-1, k-1) {
-		result = append(result, append(c, n-1))
-	}
-
-	return result
-}
-
 func TestSWAPGood(t *testing.T) {
 	prog := makeProgram(opcode.SWAP)
 	vm := load(prog)