[SYCL] Implement sycl-post-link tool

[Fznamznon]

The tool will split single big linked device module into smaller ones
using 'module-id' attribute applied to kernels.

Signed-off-by: Mariya Podchishchaeva [email protected]

[Fznamznon]

This is part of device code splitting feature. Please refer #631 for full design doc.

[keryell]

That looks good.
Just a few stylistic remarks since you are starting a new tool: this is a good opportunity to enter the 21th century. :-)

[keryell]

All these thousands of ( and ) should be { and } in a new software like this one. :-)

[keryell]

Yes! Let's be modern in 2019 and make Chandler happy! :-)

[keryell]

Twine { }

[keryell]

Twine { }

[kbobrovs]

I have a general comment. It turns out we may soon need other kinds post-link processing on the device code. So I suggest to treat this tool as a placeholder for all such post-link LLVM passes so that we don't create a new tool each time. More concretely, rename it to something like sycl-post-link/sycl-post-link.cpp

[kbobrovs]

Are these attributes required for the test to work? If not, suggest removing.

[sergey-semenov]

They are not, removed.

[sergey-semenov]

Per our agreement with Mariya, I'll be driving this PR for now.

More concretely, rename it to something like sycl-post-link/sycl-post-link.cpp

Done.

@keryell thanks for the comments. Applied most of them, the only part I disagree on is replacing parentheses with uniform initialization for constructors of temporaries. From LLVM coding standards (Do not use Braced Initializer Lists to Call a Constructor):

if you need to explicitly name the type and call its constructor to create a temporary, don’t use a braced initializer list

[keryell]

@keryell thanks for the comments. Applied most of them, the only part I disagree on is replacing parentheses with uniform initialization for constructors of temporaries. From LLVM coding standards (Do not use Braced Initializer Lists to Call a Constructor):

Interestingly, LLVM is doing the opposite of the C++ Core Guidelines https://github.com/isocpp/CppCoreGuidelines/blob/master/CppCoreGuidelines.md#Res-list

The problem I have with using parenthesis with constructors is that it is less obvious that there is some object construction when browsing the code...

[Fznamznon]

ping.