Fix/bugs (CityOfZion/neo-storm#38)

* Fixed bug where void functions cleaned up their mess multiple times
* Compiler improvements
* Fixed Neo APIs naming convention
* Added NOP after syscall for matching AVM files with neo-python.

Imported from CityOfZion/neo-storm (f93a28ef87d272a74f821d45ae0c6735a8c610be).

pkg/vm/compiler/codegen.go

@@ -87,18 +87,13 @@ func (c *codegen) emitLoadLocal(name string) {
 }
 
 func (c *codegen) emitLoadLocalPos(pos int) {
-	emitOpcode(c.prog, vm.FROMALTSTACK)
-	emitOpcode(c.prog, vm.DUP)
-	emitOpcode(c.prog, vm.TOALTSTACK)
-
+	emitOpcode(c.prog, vm.DUPFROMALTSTACK)
 	emitInt(c.prog, int64(pos))
 	emitOpcode(c.prog, vm.PICKITEM)
 }
 
 func (c *codegen) emitStoreLocal(pos int) {
-	emitOpcode(c.prog, vm.FROMALTSTACK)
-	emitOpcode(c.prog, vm.DUP)
-	emitOpcode(c.prog, vm.TOALTSTACK)
+	emitOpcode(c.prog, vm.DUPFROMALTSTACK)
 
 	if pos < 0 {
 		log.Fatalf("invalid position to store local: %d", pos)
@@ -144,6 +139,10 @@ func (c *codegen) convertFuncDecl(file ast.Node, decl *ast.FuncDecl) {
 
 	f, ok = c.funcs[decl.Name.Name]
 	if ok {
+		// If this function is a syscall we will not convert it to bytecode.
+		if isSyscall(f) {
+			return
+		}
 		c.setLabel(f.label)
 	} else {
 		f = c.newFunc(decl)
@@ -262,14 +261,13 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 		// To be backwards compatible we will put them them in.
 		// See issue #65 (https://github.com/CityOfZion/neo-go/issues/65)
 		l := c.newLabel()
-		emitJmp(c.prog, vm.JMP, int16(l))
+		// emitJmp(c.prog, vm.JMP, int16(l))
 		c.setLabel(l)
 
 		if len(n.Results) > 0 {
 			ast.Walk(c, n.Results[0])
 		}
 
-		emitOpcode(c.prog, vm.NOP) // @OPTIMIZE
 		emitOpcode(c.prog, vm.FROMALTSTACK)
 		emitOpcode(c.prog, vm.DROP) // Cleanup the stack.
 		emitOpcode(c.prog, vm.RET)
@@ -425,11 +423,6 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 			}
 		}
 
-		// c# compiler adds a NOP (0x61) before every function call. Dont think its relevant
-		// and we could easily removed it, but to be consistent with the original compiler I
-		// will put them in. ^^
-		emitOpcode(c.prog, vm.NOP)
-
 		// Check builtin first to avoid nil pointer on funcScope!
 		switch {
 		case isBuiltin:
@@ -442,11 +435,6 @@ func (c *codegen) Visit(node ast.Node) ast.Visitor {
 			emitCall(c.prog, vm.CALL, int16(f.label))
 		}
 
-		// If we are not assigning this function to a variable we need to drop
-		// (cleanup) the top stack item. It's not a void but you get the point \o/.
-		if _, ok := c.scope.voidCalls[n]; ok {
-			emitOpcode(c.prog, vm.DROP)
-		}
 		return nil
 
 	case *ast.SelectorExpr:
@@ -540,7 +528,10 @@ func (c *codegen) convertSyscall(api, name string) {
 		log.Fatalf("unknown VM syscall api: %s", name)
 	}
 	emitSyscall(c.prog, api)
-	emitOpcode(c.prog, vm.NOP) // @OPTIMIZE
+
+	// This NOP instruction is basically not needed, but if we do, we have a
+	// one to one matching avm file with neo-python which is very nice for debugging.
+	emitOpcode(c.prog, vm.NOP)
 }
 
 func (c *codegen) convertBuiltin(expr *ast.CallExpr) {

pkg/vm/compiler/syscall.go

@@ -2,45 +2,45 @@ package compiler
 
 var syscalls = map[string]map[string]string{
 	"storage": {
-		"GetContext": "System.Storage.GetContext",
-		"Put":        "System.Storage.Put",
-		"Get":        "System.Storage.Get",
-		"Delete":     "System.Storage.Delete",
-		"Find":       "System.Storage.Find",
+		"GetContext": "Neo.Storage.GetContext",
+		"Put":        "Neo.Storage.Put",
+		"Get":        "Neo.Storage.Get",
+		"Delete":     "Neo.Storage.Delete",
+		"Find":       "Neo.Storage.Find",
 	},
 	"runtime": {
-		"GetTrigger":   "System.Runtime.GetTrigger",
-		"CheckWitness": "System.Runtime.CheckWitness",
-		"Notify":       "System.Runtime.Notify",
-		"Log":          "System.Runtime.Log",
-		"GetTime":      "System.Runtime.GetTime",
-		"Serialize":    "System.Runtime.Serialize",
-		"Deserialize":  "System.Runtime.Deserialize",
+		"GetTrigger":   "Neo.Runtime.GetTrigger",
+		"CheckWitness": "Neo.Runtime.CheckWitness",
+		"Notify":       "Neo.Runtime.Notify",
+		"Log":          "Neo.Runtime.Log",
+		"GetTime":      "Neo.Runtime.GetTime",
+		"Serialize":    "Neo.Runtime.Serialize",
+		"Deserialize":  "Neo.Runtime.Deserialize",
 	},
 	"blockchain": {
-		"GetHeight":      "System.Blockchain.GetHeight",
-		"GetHeader":      "System.Blockchain.GetHeader",
-		"GetBlock":       "System.Blockchain.GetBlock",
-		"GetTransaction": "System.Blockchain.GetTransaction",
-		"GetContract":    "System.Blockchain.GetContract",
+		"GetHeight":      "Neo.Blockchain.GetHeight",
+		"GetHeader":      "Neo.Blockchain.GetHeader",
+		"GetBlock":       "Neo.Blockchain.GetBlock",
+		"GetTransaction": "Neo.Blockchain.GetTransaction",
+		"GetContract":    "Neo.Blockchain.GetContract",
 		"GetAccount":     "Neo.Blockchain.GetAccount",
 		"GetValidators":  "Neo.Blockchain.GetValidators",
 		"GetAsset":       "Neo.Blockchain.GetAsset",
 	},
 	"header": {
-		"GetIndex":         "System.Header.GetIndex",
-		"GetHash":          "System.Header.GetHash",
-		"GetPrevHash":      "System.Header.GetPrevHash",
-		"GetTimestamp":     "System.Header.GetTimestamp",
+		"GetIndex":         "Neo.Header.GetIndex",
+		"GetHash":          "Neo.Header.GetHash",
+		"GetPrevHash":      "Neo.Header.GetPrevHash",
+		"GetTimestamp":     "Neo.Header.GetTimestamp",
 		"GetVersion":       "Neo.Header.GetVersion",
 		"GetMerkleRoot":    "Neo.Header.GetMerkleRoot",
 		"GetConsensusData": "Neo.Header.GetConsensusData",
 		"GetNextConsensus": "Neo.Header.GetNextConsensus",
 	},
 	"block": {
-		"GetTransactionCount": "System.Block.GetTransactionCount",
-		"GetTransactions":     "System.Block.GetTransactions",
-		"GetTransaction":      "System.Block.GetTransaction",
+		"GetTransactionCount": "Neo.Block.GetTransactionCount",
+		"GetTransactions":     "Neo.Block.GetTransactions",
+		"GetTransaction":      "Neo.Block.GetTransaction",
 	},
 	"transaction": {
 		"GetType":         "Neo.Transaction.GetType",
@@ -76,10 +76,10 @@ var syscalls = map[string]map[string]string{
 		"GetScriptHash": "Neo.Output.GetScriptHash",
 	},
 	"engine": {
-		"GetScriptContainer":     "System.ExecutionEngine.GetScriptContainer",
-		"GetCallingScriptHash":   "System.ExecutionEngine.GetCallingScriptHash",
-		"GetEntryScriptHash":     "System.ExecutionEngine.GetEntryScriptHash",
-		"GetExecutingScriptHash": "System.ExecutionEngine.GetExecutingScriptHash",
+		"GetScriptContainer":     "Neo.ExecutionEngine.GetScriptContainer",
+		"GetCallingScriptHash":   "Neo.ExecutionEngine.GetCallingScriptHash",
+		"GetEntryScriptHash":     "Neo.ExecutionEngine.GetEntryScriptHash",
+		"GetExecutingScriptHash": "Neo.ExecutionEngine.GetExecutingScriptHash",
 	},
 	"iterator": {
 		"Create": "Neo.Iterator.Create",