* Add method to check if an Executable can create tensors

* Add a Backend check to see if Executable can create tensors

* Update per review comment

* style

* update fused_clamp

* convert all f64 to f32

* [MLIR] Bump MLIR repo to commit c636f12, 08/09/2019

MLIR Commit:
commit c636f127ee412ef7279ec0d550f42740824cd9ea
Author: Alex Zinenko <zinenko@google.com>
Date:   Fri Aug 9 08:59:45 2019 -0700

    LLVM dialect and translation: support global strings

LLVM Commit:
commit c636f127ee412ef7279ec0d550f42740824cd9ea
Author: Alex Zinenko <zinenko@google.com>
Date:   Fri Aug 9 08:59:45 2019 -0700

    LLVM dialect and translation: support global strings

* [MLIR] Set optimization level for LLVM optimizer and codegen

Now both LLVM optimizer and codegen are aligned with
"NGRAPH_MLIR_OPT_LEVEL" macro.

* [MLIR] Enable LLVM vectorization by initializing TTI

This is the final piece to enable LLVM vectorization for MLIR compiler.
The PR refactors the creation of a target machine in MLIRCompiler so that
we can use it to initialize TargetTransformInfo with the proper host
features and LLVM Loop Vectorizer can get the right vector register
information of the target CPU.

* Axes input was added to LRN

* Unit tests for axes shape check were added

* LRN node deserialization was updated

* Fixed EOF and clang style applied

* Changed Constant to Parameter type in unit tests

* Fixed LRN assert description

* Fixed copy_with_new_args

* Clang style applied

* wip

* parse working with one test

* Add version information query and unit tests for parsing version strings

* add more comments

* doc strings

* style

Now both LLVM optimizer and codegen are aligned with
"NGRAPH_MLIR_OPT_LEVEL" macro.

* Update cpu backend to support i32 with topk

* Add topk i32 unit test

* Minor fix in unit-test

* disable test for plaidml

MLIR Commit:
commit c636f127ee412ef7279ec0d550f42740824cd9ea
Author: Alex Zinenko <zinenko@google.com>
Date:   Fri Aug 9 08:59:45 2019 -0700

    LLVM dialect and translation: support global strings

LLVM Commit:
commit c636f127ee412ef7279ec0d550f42740824cd9ea
Author: Alex Zinenko <zinenko@google.com>
Date:   Fri Aug 9 08:59:45 2019 -0700

    LLVM dialect and translation: support global strings

* Add negative op

* Add test case

* Address feedback

* Merge master

* Consolidate to one routine for unary ops

* Change from Negative to Neg

* [MLIR] Enable affine loop tiling

This PR enables loop tiling optimization in affine dialect. It
introduces the following flags for configuration.
  - affine-loop-tile: enables/disables the optimization. Disabled by
    default.
  - loop-tile-cache-level: provides the cache level to which apply loop
    tiling to. Cache level size is obtained from LLVM's TTI.
  - loop-tile-cache-size: provides a cache level size that overrides
    cache information from TTI.

The current use of TTI is a bit hacky since we have to pass a fake
LLVM's function to make it work. However, this should be enough to get
some basic target information until we have a target model in MLIR or
find a better approach.

* Address feedback

* Rename flags

* Fix sum reference to handle corner cases with +-inf

* Review comments, and try to make Windows happy

* Update GPU unit_test.manifest

* More template grindery, to make macOS happy

* wip

* compiles and links

* style

* wip

* parse working with one test

* Add version information query and unit tests for parsing version strings

* add more comments

* doc strings

* style

Remove not-directly-used includes

* Fix crash when NGRAPH_ENABLE_{VISUALIZE,SERIALIZE}_TRACING=1

* Initialization for kw

Cyphers/25tomaster

Update CODEOWNERS

Convert remaining experimental op dir to output args

Cyphers/s barannikov initialize dyn pad mode