[Openmp-commits] [PATCH] D101509: An attempt to abandon omptarget out-of-tree builds.

[Vyacheslav Zakharin via Phabricator via Openmp-commits]

vzakhari added a comment.

In D101509#2725624 <https://reviews.llvm.org/D101509#2725624>, @JonChesterfield wrote:

> In D101509#2725126 <https://reviews.llvm.org/D101509#2725126>, @mgorny wrote:
>
>> In D101509#2725078 <https://reviews.llvm.org/D101509#2725078>, @JonChesterfield wrote:
>>
>>> In D101509#2724846 <https://reviews.llvm.org/D101509#2724846>, @mgorny wrote:
>>>
>>>> Is this going to block all direct builds of openmp or just these that don't have an LLVM source tree handy?
>>>
>>> This is aimed at libomptarget, libopenmp can still build without llvm, provided it excludes the target part.
>>
>> This doesn't really answer my question.
>
> Perhaps you could rephrase the question? This patch is intended to leave openmp building exactly like it used to. The subcomponent libomptarget would no longer build without access to the llvm libraries, but that subcomponent is optional.
>
> In D101509#2725137 <https://reviews.llvm.org/D101509#2725137>, @protze.joachim wrote:
>
>> For me, the main use-case for stand-alone builds is runtime code development. In that case, I use a ("nightly") build of LLVM and use that to compile and test stand-alone runtime builds. 
>> Switching branches regularly results in recompiling a lot of code. With stand-alone runtime builds, this is restricted to OpenMP runtime code.
>>
>> If you really only depend on LLVM libraries and header files, they should get installed. find_package(LLVM) should provide you all necessary information to include and link those libraries.
>
> That is interesting. The header files used by libomptarget may not be on the installed list, but perhaps they should be. For efficient development purposes, using headers from the source tree with binaries from somewhere on disk would be great, provided that slight mashup works. I've been building llvm from scratch repeatedly, changing to a find_package workflow would do good things for iteration time.

Right, we were also talking about find_package(LLVM) here: D99553#2687851 <https://reviews.llvm.org/D99553#2687851>
I do not have much experience with this approach, but I will try to make it work.

@mgorny, if we switch to find_package(LLVM), one will need a built/installed LLVM to build libomptarget in addition to libopenmp.  To link LLVM component libraries into libomptarget I would like to use LLVM macros provided in LLVM CMake files.  Aligning the libomptarget build options with LLVM build options (e.g. EH, RTTI related options) will be a pain otherwise.


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https://reviews.llvm.org/D101509