[llvm-dev] [RFC][clang/llvm] Allow efficient implementation of libc's memory functions in C/C++

[Guillaume Chatelet via llvm-dev]

A POC patch is available here for discussion
https://reviews.llvm.org/D61634

On Tue, Apr 30, 2019 at 6:28 PM David Chisnall <David.Chisnall at cl.cam.ac.uk>
wrote:

> On 30/04/2019 15:01, Guillaume Chatelet wrote:
> > David what do you think about the additional version that restrict the
> > effect to a few named functions?
> >  > e.g. __attribute__((disable_call_synthesis("memset", "memcpy",
> "sqrt")))
>
> I would find that exceptionally useful.  For the libm example,
> preventing LLVM from synthesising calls to other libm functions that may
> call this one would be the fine-grained control that we want.  For an
> Objective-C runtime, being able to explicitly disable synthesising ARC
> calls would be similarly useful (though I can no longer construct an
> example where LLVM does the wrong thing, so maybe this is fixed already
> in the ARC passes).
>
> David
>
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