[RUNTIME][GOLANG] TVM runtime for golang v0.1

[srkreddy1238]

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[tqchen]

It is a good start, I would recommend to not use swig but directly use the C FFI in Go, and do a bit wrapping to support Module and TVMValue class like in jvm,

c.f. https://github.com/jdeng/gomxnet

[srkreddy1238]

@tqchen

Ref. gomxnet above
I see it implements a new API layer for go instead of mxnet original. Do we define a new API layer for go?

Reason I choose swig was to keep the interface maintenance automatic for changes to c_runtime_api.
And both ways here use same unsafe and C packages below.

pls advice.

[tqchen]

I think doing a bit minimum wrapping to make things more native to the language(in this case go) is useful, Take a look at tvm4j and the wrapping being done there

[srkreddy1238]

@tqchen

I checked the tvm4j and tried to wrap few types inside TVMvalue.

I see other challenges in wrapping the go slices to C arrays for TVMValue array itself and other primitive types. golang use slices very common instead of arrays which complicates the interface.

Hand coding slice to a array for all these types via "C" and "unsafe" need more effort and results almost same like the swig generated interface.

Please advice.

[tqchen]

I think if we can build an NDArray.copyfrom(go_slice) function, it will work for most case. The data conversion happens inside the function itself, so it is invisible to the users.

BTW, in terms of package name, seems gotvm is a more canonical name for golang projects :)

[srkreddy1238]

@tqchen please have a look.
If the code structure and API naming are good I will finish the few pending API and conclude.

@dmlc/tvm-reviewer welcome to review and comment.

[tqchen]

@srkreddy1238 Can you do additional wrappings to provide the following class object?

• TVMFunction
• TVMModule
• TVMArray
• TVMValue(for handling return value conversion)

[srkreddy1238]

Sure, I will add above class objects.

[tqchen]

Also please add appropriate documentation for user-facing objects and methods, as per https://blog.golang.org/godoc-documenting-go-code

[srkreddy1238]

@tqchen

• Added wrappers for TVMModule, TVMFunction
• Dropped DLTensor and given TVMArray instead.
• TVMValue getter/setter for all these types.
• Documentation as per the standard.
• golint addition for Make script.

[srkreddy1238]

@tqchen ready for review.

Recent changes

• Simplify the getter and setter on TVMValue user interface.
• GetFunction and FuncCall are simplified TVMFuncExec which take funcname and variable args.

[tqchen]

gotvm

[srkreddy1238]

Done

[tqchen]

provide wrapping in c/c++ via extern "C" and __cplusplus

[srkreddy1238]

gotvm.h ideally should be a command followed by import "C"
cgo picks up picks it it from commented code.

No problem, extern works here well.

Done

[tqchen]

unless it is the convention, use gotvm.cc

[tqchen]

I made some simple comments, but the wrapping is still a bit raw(it reads more like C rather than Go), here is what we want ideally(note I am not expert in Go, so syntax might be wrong)

mod = gotvm.LoadFromFile("/path/to/mymodule.so")
f1 = mod.GetFunction("myfunction")
# need to debate how to support function invocation, either in normal style or java style
f1.invoke(args) 

myarr = gotvm.empty(shape, ctx);

[tqchen]

Actually since, this involves API design discussion, can you please open an RFC issue so that more people can participate? Maybe there are good ideas from the community, I am not expert in Go, so I can only generalize from my experience in other languages

[srkreddy1238]

#1559 for a discussion with team.

[srkreddy1238]

@tqchen

f1 = mod.GetFunction("myfunction")
f1.invoke(args) 
f1.free()

The new API TVMFunctionExec ideally does all these. I could keep as above based on the duscussion result.

[srkreddy1238]

Thanks @grwlf. Addressed the review comments.

[tqchen]

OK, if there is no further comments, I will merge this PR in 24 hours. Thanks @grwlf for the reviews.

[tqchen]

Thanks, @grwlf for the detailed reviews, Thanks, @srkreddy1238 for patiently improving the code during the review process. This is now merged. Please send in followup PRs to enable the test in CI