can not run smart contract script, the vm throw FAULT message.

[shelmesky]

First i start local neo node by run this command: make run, then i try to run smart contract script token_sale.go:

NEO-GO-VM > loadgo token_sale.go
READY: loaded 2996 instructions
NEO-GO-VM > run
NEO-GO-VM > error encountered at instruction 9 (Oroll)
NEO-GO-VM > runtime error: invalid memory address or nil pointer dereference
FAULT
NEO-GO-VM > error encountered at instruction 10 (Osetitem)
NEO-GO-VM > interface conversion: interface {} is []vm.StackItem, not []uint8
FAULT
NEO-GO-VM 10 >

[anthdm]

@shelmesky Thanks for your bug report, The old neo-go VM have some issues on new API's I implemented. I'm currently rewriting the VM to be compatible with the new APIS that are in neo-storm. This will not take longer then a week. I will keep you posted on this issue when its completed. The improved VM will also house in the neo-storm repository. Thanks for your understanding.

[shelmesky]

Thank you @anthdm . I have check the neo-storm repository, but i can not find a virtual machine in there. Can you tell me where to find a runnable virtual machine and written by golang? thanks a lot!

[anthdm]

@shelmesky I'm currently working on it :) should not take to long. 2 weeks max.

[hal0x2328]

@anthdm Is this completed?

[im-kulikov]

@hal0x2328 nope, I test that yesterday

[roman-khimov]

Reproducible on current master:

$ go run cli/main.go vm

    _   ____________        __________      _    ____  ___
   / | / / ____/ __ \      / ____/ __ \    | |  / /  |/  /
  /  |/ / __/ / / / /_____/ / __/ / / /____| | / / /|_/ / 
 / /|  / /___/ /_/ /_____/ /_/ / /_/ /_____/ |/ / /  / /  
/_/ |_/_____/\____/      \____/\____/      |___/_/  /_/   


NEO-GO-VM > loadgo examples/token-sale/token_sale.go
READY: loaded 3017 instructions
NEO-GO-VM > run
NEO-GO-VM > error encountered at instruction 9 (Oroll)
NEO-GO-VM > runtime error: invalid memory address or nil pointer dereference
FAULT
NEO-GO-VM > error encountered at instruction 10 (Osetitem)
NEO-GO-VM > interface conversion: interface {} is []vm.StackItem, not []uint8
FAULT

[roman-khimov]

I think the problem actually is in the codegen, it can be simplified to this one

$ cat h.go
package tokensale

func Main(operation string, args []interface{}) interface{} {
        return true
}
$ ./bin/neo-go vm

    _   ____________        __________      _    ____  ___
   / | / / ____/ __ \      / ____/ __ \    | |  / /  |/  /
  /  |/ / __/ / / / /_____/ / __/ / / /____| | / / /|_/ / 
 / /|  / /___/ /_/ /_____/ /_/ / /_/ /_____/ |/ / /  / /  
/_/ |_/_____/\____/      \____/\____/      |___/_/  /_/   


NEO-GO-VM > loadgo h.go
READY: loaded 17 instructions
NEO-GO-VM > ops
INDEX    OPCODE    DESC               
0        0x53      PUSH3              
1        0xc5      NEWARRAY           
2        0x6b      TOALTSTACK         
3        0x6a      DUPFROMALTSTACK    
4        0x 0      PUSH0              
5        0x52      PUSH2              
6        0x7a      ROLL               
7        0xc4      SETITEM            
8        0x6a      DUPFROMALTSTACK    
9        0x51      PUSH1              
10       0x52      PUSH2              
11       0x7a      ROLL               
12       0xc4      SETITEM            
13       0x51      PUSH1              
14       0x6c      FROMALTSTACK       
15       0x75      DROP               
16       0x66      RET                
NEO-GO-VM > run
NEO-GO-VM > error encountered at instruction 6 (ROLL)
NEO-GO-VM > runtime error: invalid memory address or nil pointer dereference
FAULT
NEO-GO-VM > error encountered at instruction 7 (SETITEM)
NEO-GO-VM > interface conversion: interface {} is []vm.StackItem, not []uint8
FAULT

It tries to get the stack item with index number 2 with ROLL, but it doesn't exist. But there are also some issues in the VM: nil pointer dereference (instead of error detection and messaging) and execution of the next instruction in FAULT state.

[roman-khimov]

Or it's not an issue on the compiler side at all, because it can be reduced even further to:

package tokensale

func Main(operation int) interface{} {
 return true
}

And in all these examples Main() has some parameters that it expects to be passed into it while we're not actually passing (putting on the stack) anything, so it breaks. What we're missing at the moment is the possibility to pass parameters to the VM script from CLI (also true for testinvoke contract functionality).

[roman-khimov]

Closing this one, minor problems were fixed in #331 and parameters are subject of #332.