[PATCH] D85627: [polly][cmake] Don't build LLVMPolly.so without PIC

Wed Aug 26 11:58:34 PDT 2020

Meinersbur accepted this revision.
Meinersbur added a comment.
This revision is now accepted and ready to land.

In D85627#2226214 <https://reviews.llvm.org/D85627#2226214>, @ro wrote:

> In D85627#2206550 <https://reviews.llvm.org/D85627#2206550>, @Meinersbur wrote:
>
>> 
>
> What do you mean by intended solution?  My intent was to avoid breaking the build with PIC code turned off.  Just as Windows doesn't support loadable modules and thus creation of `LLVMPolly.so` is disabled, it's just not possible to build a loadable module/shared object without PIC code, so there's no choice but to disable it.

I had a warning in mind, but you are right, there is no warning for Windows either. I didn't see the similarity. I could still be improved.

The other issue is that LLVM_ENABLE_PIC is defined by LLVM's CMakeLists.txt, but that is not processed when Polly is built out-of-tree (`cmake -S llvm-project/polly`), i.e. it this patch would never build `LLVMPolly.so` when configuring this way.
Anyway, I invested some time to see that LLVM_ENABLE_PIC uf actually is defined when building out-of-tree, defined by the imported LLVMConfig.cmake.

Hence, no fundamental problem and patch LGTM.

Repository:
  rG LLVM Github Monorepo

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https://reviews.llvm.org/D85627