[PATCH] [ARM] Use function attribute "arm-long-calls"

[Akira Hatanaka]

Hi Renato,

I realized today the title and summary I wrote were terribly uninformative, but this patch is part of the work to make LTO and function multi-versioning work correctly. In order to accomplish this, we have to save the command line option (-arm-long-calls) in the IR as a function attribute and fix the backend to check for the attribute so that it can decide on a per-function basis whether it should be emitting long calls.

As for the inlining part, my reasoning is that it's probably fine to compile a function that doesn't have attribute "arm-long-calls" as a function that does have the attribute, but not the other way around as it might turn a call that was in range into a call that is out of range. I used the word "conservative" as this patch rejects both cases even though it might not be necessary to reject the first case. I'm not sure how the inlining decision affects interworking (I'm assuming arm-thumb interworking?) though.


http://reviews.llvm.org/D9364

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