* [bugfix][codegen] fix casting bug in llvm codegen

* update example

* retrigger ci

* check llvm version

* count MAC for BatchMatMul

* update doc

FIX "After connecting he usb" with "After connecting the usb"

This patch adds multiply operator for quantized tensors.
The details of the quantized multiplication are outlined
in the code.

This builds on pull request 3927 and includes the changes
Animesh mentions in the comments on that request.

Change-Id: I555715b53d0266a91d5c03dc3dfe8fc31e7ce4e1

* [REFACTOR][NODE][RUNTIME] Move Node to the new Object protocol.

This PR removes the original node system, and make node as a subclass of Object.
This is a major refactor towards a better unified runtime object system.

List of changes in the refactor:

- We now hide data_ field, use Downcast explicitly to get a sub-class object.
- Removed the node system FFI in python.
- Removed the node C API, instead use PackedFunc for list and get attrs.
- Change relay::Op::set_attr_type_key(attr_key_name) to relay::Op::set_attr_type<AttrType>().
  - This change was necessary because of the new Object registration mechanism.
  - Subsequent changes to the op registrations
  - The change revealed a few previous problems that is now fixed.
- Patched up a few missing node type registration.
  - Now we will raise an error if we register object that is not registered.
- The original node.h and container.h are kept in the same location.
- Calling convention: kObjectHandle now equals the old kNodeHandle, kNodeHandle is removed.
- IRFunctor now dispatches on ObjectRef.
- Update to the new type checking API: is_type, derived_from are replaced by IsInstance.
- Removed .hash member function, instead use C++ convention hasher functors.

* Address review comments

We think it will reduce the confusion with the meaning.

https://discuss.tvm.ai/t/discuss-consider-rename-vm-datatype/4339

* Add LiftIfThenElse pass

* Add more comments

* Rename and refactor

* Add description for internal data structure

* Rename a test

* Minor change

* Address comments

* Improve update_for

* [Relay][Frontend][TF] Add tensor array ops

* rename

* delete test

* Move utility function

* Refactor

* fix tensor array ops

* fix test

* fix rebase

* Fix serializer bug

* Improve tf convert name lookup to use prelude api

* Fix lint

* Fix test

* [relay][vm] Separate VM runtime with executable

* Address comments

* move ctx back to vm

* make only vm related fields and methods protected

* integrate seriliaztion/deserialization to executable

* create stream

Arm architecture provides optional FP16 floating point support in two alternative formats, IEEE and an an alternative Arm format.

The ACLE (Arm C Language Extension) defined preprocessor symbol __ARM_FP16_FORMAT_IEEE can be used to distinguish between implementations providing IEEE and the Arm alternative format, but cannot, on its own, be used to determined if FP16 HW support is actually present.

Testing this preprocessor symbol can lead to undefined __floatdihf at runtime on an aarch64 target where no FP16 HW is present.

The relevant preprocessor symbol to determine whether FP16 HW support is present in the target is __ARM_FEATURE_FP16_SCALAR_ARITHMETIC, this symbol implies  __ARM_FP16_FORMAT_IEEE.

The relevant preprocessor symbols are defined by the ACLE standard, section 5.5.21 16-bit floating-point data processing operations, https://static.docs.arm.com/101028/0008/Q2-ACLE_2019Q2_release-0008.pdf

The existing sequence of pip install commands fetches and installs
torch==1.0.1.post2 then fetches an unpinned version of torchvision,
recent torchvision packages hardwire the specific torch version they
depend on, the overall effect is that we install a pinned torch
version then replace it with whatever version the torchvision package
depends on.

The most recent torchvision==0.4.1 package results in some test case
failures.

This patch pins torchvision back to 0.4.0, the most recent version
that the test suite worked.  Removing the explicit torch install
because it is implied and pinned as dependency of torchvision.

Change-Id: Ib30bf6aed79ff130ea15ef5134fefb0508790574

* [TOPI][x86] Cascade lake support.

* Jenkins test debug 1.

* Testing cascade lake alone.

* Improve build error when no lowered funcs

* Switch from fatal to warning

* [RUNTIME] Refactor object python FFI to new protocol.

This is a pre-req to bring the Node system under object protocol.
Most of the code reflects the current code in the Node system.

- Use new instead of init so subclass can define their own constructors
- Allow register via name, besides type idnex
- Introduce necessary runtime C API functions
- Refactored Tensor and Datatype to directly use constructor.

* address review comments

* add and fix gradients

* fix linter issues

* Fix infer type of kernel in dense.

* - Moving the check of weight being nullptr up as it is needed in both the branches now.
- Adding test case for validating that data dtype and kernel dtypes can be different.

* - Fix the dtype check for weight. If the weight is not present then we will use the data dtype.

* [Relay][AlterOpLayout] NHWC to NCHWc pad operator.

* Fixing culprit.

* Flaky test 1.

* Flaky test 2.

* [RUNTIME] Introduce new object protocol.

This PR introduces a new object protocol to unify the node and object.
We also updated the existing runtime::vm code to make use of the new system.

Update to the node will be done in a follow up PR.

Other changes:

- Remove object related code in json serializer as that code logic was not complete
  and we have a separate serializer for VM, can revisit later.

* address review  comment

* Fix the child slot logic

This implementation provides cast to limited number of dtypes
that tflite currently supports for placeholder op. Add INT64 in the
possible dtypes as it appears to be supported accrording to tlfite schema.

* overload half operators for cuda codegen

* add float16 te test_op_level1

* fix test_op_level1.py

* fix lint

* disable fp16 test if gpu does not support

* disable fp16 test if gpu does not support

* bypass float16 test if gpu does not support float16