[llvm-dev] [compiler-rt] '-fprofile-generate' and embedded systems

[Simon Whittaker via llvm-dev]

Hi Martin,

Can't you just port enough to get the existing:

__llvm_profile_write_buffer

functionality working? This shouldn't depend on IO. You then have free
choice of how to get that buffer to somewhere persistent.

This is something we use on PlayStation, in addition to the more usual
"write a file" path.

Thanks,

Simon


On 25 May 2017 7:07 a.m., "Martin J. O'Riordan via llvm-dev" <
llvm-dev at lists.llvm.org> wrote:

Yep, done that already, but it is not at all a good fit when the device is
inside a drone flying around ;-)  What we do have, is a fake file-system
that keeps everything in memory, and after the profiling is completed we
offload it for analysis.  I guess I was hoping that there would be a more
robust system agnostic implementation.  Use of ‘mmap’ is similarly
constraining.



            MartinO



*From:* Nicholas Wilson [mailto:iamthewilsonator at hotmail.com]
*Sent:* 25 May 2017 14:39
*To:* Martin J. O'Riordan <martin.oriordan at movidius.com>
*Cc:* LLVM Developers <llvm-dev at lists.llvm.org>
*Subject:* Re: [llvm-dev] [compiler-rt] '-fprofile-generate' and embedded
systems



Well you could always write a ‘filesystem’ that shunts all data out the
serial port (or similar).



On 25 May 2017, at 9:12 pm, Martin J. O'Riordan via llvm-dev <
llvm-dev at lists.llvm.org> wrote:



What is the best way of porting the ‘compiler-rt’ Profile library for an
embedded system with no file-system (and hence no ‘fopen’, etc.)?



What I would like to do is use it as normal, but then use a custom solution
for getting the resulting data off the system.  It seems that this library
(and the other compiler-rt libraries) are designed only to work with a
hosted system.



Are there any other embedded targets that this has been adapted for which
would have similar constraints?



Thanks,



            MartinO



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