Fix missing round(), floor(), ceil() for target C lowering

[cbalint13]

• Trying to lower quantized C target some simple nets reveal missing round, floor, ceil translation.

   with relay.build_config(opt_level=3):
      graph, c_mod, c_params = relay.build(mod, target='c', params=params)

• Network looks like the one below, notice for example the round operations:

#[version = "0.0.5"]
def @main(%input_3: Tensor[(1, 1, 129, 124), float32]) -> Tensor[(?, 8), float32] {
  %0 = dyn.image.resize(%input_3, meta[relay.Constant][0] /* ty=Tensor[(2), int64] */, size=[]) /* ty=Tensor[(1, 1, ?, ?), float32] */;
  %1 = multiply(%0, 16f /* ty=float32 */) /* ty=Tensor[(1, 1, ?, ?), float32] */;
  %2 = round(%1) /* ty=Tensor[(1, 1, ?, ?), float32] */;
  .....
  .....

• The errors encountered:

TVMError: Unresolved call Op(tir.round)
TVMError: Unresolved call Op(tir.floor)
TVMError: Unresolved call Op(tir.ceil)

---

• This simple patch address the issue.

@jroesch @masashi @mdw-octoml Please help me review.

Thank you !

[mdw-octoml]

LGTM, thanks! @areusch

[manupak]

Thanks for the PR! a much needed one :).

one suggestion and I think it would better if we can have some test cases in tests/python/unittest/test_target_codegen_c_host.py to cover these.

[areusch]

thanks @cbalint13! this looks good but would be great if you could write a test case to prevent regressions in the future. I think the tests/python/unittest/test_target_codegen_c_host.py is a good place for that.

[cbalint13]

@mdw-octoml , @areusch , @manupa-arm

• Added missing to target/intrin_rule.cc (as @tqchen suggested).
• Added test cases to check C lowering.
• Prepended test_ local funcs of testunit avoiding name conflict with <math.h>
• C generated code is properly lowered to C function calls:

((float*)B)[(i0)] = ceilf(((float*)A)[(i0)]);
((float*)B)[(i0)] = floorf(((float*)A)[(i0)]);
((float*)B)[(i0)] = roundf(((float*)A)[(i0)]);

[manupak]

LGTM

[tqchen]

Thanks @cbalint13 @manupa-arm @mdw-octoml @areusch