[llvm-dev] Profile-based inlining status

[Mehdi Amini via llvm-dev]

> On Mar 7, 2016, at 8:58 AM, Toshio Suganuma via llvm-dev <llvm-dev at lists.llvm.org> wrote:
> 
> Hello,
> 
> I'm learning how LLVM performs PGO (profile-guided optimizations) by using the instrumentation-based profile build (-fprofile-instr-generate and -fprofile-instr-use).
> However, I found there is no difference in inlining behaviors between with and without PGO for a few spec benchmarks by checking the emit optimization reports (-Rpass=inline -Rpass-missed=inline -Rpass-analysis=inline). Also, the profile information collected contains only block counters, not call counters.
> 
Since a call is necessarily in a block, I'm not sure what extra information you would get with a call counter?

> This seems to indicate that the profile-based inlining is not supported yet (my LLVM/Clang is 3.9.0, mid Feb trunk). Is this the case?
> 
> The talk in the LLVM conference 2013 (http://llvm.org/devmtg/2013-11/slides/Carruth-PGO.pdf <http://llvm.org/devmtg/2013-11/slides/Carruth-PGO.pdf>) actually describes that "the inliner doesn't even know profile information exists today" (page 89), but it's been more than two years since that statement. Can you let me know the latest status or any ongoing work for the profile-based inlining (both same-module and cross-module inlining)?
> 
I believe it was added recently (last December, see http://reviews.llvm.org/D15245 ), so a trunk version should definitely have it.

-- 
Mehdi
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-dev/attachments/20160307/9bd3526e/attachment.html>