This solves two problems:
* adds support for shortened SYSCALL form that uses IDs (similar to #434, but
for NEO 2.0, supporting both forms), which is important for compatibility
with C# node and mainnet chain that uses it from some height
* reworks interop plugging to use callbacks rather than appending to the map,
these map mangling functions are clearly visible in the VM profiling
statistics and we want spawning a VM to be fast, so it makes sense
optimizing it. This change moves most of the work to the init() phase
making VM setup cheaper.
Caveats:
* InteropNameToID accepts `[]byte` because that's the thing we have in
SYSCALL processing and that's the most often usecase for it, it leads to
some conversions in other places but that's acceptable because those are
either tests or init()
* three getInterop functions are: `getDefaultVMInterop`, `getSystemInterop`
and `getNeoInterop`
Our 100K (1.4M->1.5M) block import time improves by ~4% with this change.
Add `Roll` method to Stack that doesn't pop and push values and use it for
ROLL and ROT.
1.4M->1.5M 100K block import test before:
real 3m44,292s
user 5m43,494s
sys 0m34,741s
After:
real 3m40,449s
user 5m42,701s
sys 0m35,500s
Add `Swap` method to the Stack and use it for both SWAP and XSWAP. Avoid
element popping and pushing (and associated accounting costs).
1.4M->1.5M 100K block import test before:
real 3m51,885s
user 5m54,744s
sys 0m38,444s
After:
real 3m44,292s
user 5m43,494s
sys 0m34,741s
This change (closely related to the neo-project/neo#1321 proposal) speeds up
1.4M mainnet blocks import by 30%. Basically, we're eliminating key decoding
for block's multisignature that has the same keys most of the time.
Things I don't like about this patch:
* yet another parameter for verifyHashAgainstScript()
* vm keys are not copied in/out
But it's rather simple and solves the problem for this particular case, so I
think it's worth it.
This allows easier reuse of opcodes and in some cases allows to eliminate
dependencies on the whole vm package, like in compiler that only needs opcodes
and doesn't care about VM for any other purpose.
And yes, they're opcodes because an instruction is a whole thing with
operands, that's what context.Next() returns.
When encountering already seen stack item we should fail
only if it is a collection. Duplicate Integers or ByteArrays are ok
because they can't lead to recursion.
VM should be responsible for code execution and in case anyone interested in additional logging or errors they could handle them like we do it iin cli.
When performing NEWARRAY on a Struct or NEWSTRUCT on a Array,
underlying slice needs to be copied, because when it's capacity
doesn't matches it's length, underlying storage will be used
for appends even if it is already pointed at by another slice.
