[llvm-commits] [PATCH] New external2availableexternally pass (issue166075)

[Jeffrey Yasskin]

Anyone have comments?

On Sun, Dec 6, 2009 at 2:32 AM, Jeffrey Yasskin <jyasskin at gmail.com> wrote:
> On Sun, Dec 6, 2009 at 12:35 AM, Duncan Sands <baldrick at free.fr> wrote:
>> Hi,
>>
>>> When we have a runtime library, it's useful to expose that library to
>>> the optimizers, but it's bad to ask LLVM to actually codegen the
>>> library's code a second time.
>>
>> I didn't look at the code, but it sounds like it gives functions
>> available_externally linkage.
>
> Yes.
>
>> Why not have the front-end output
>> the functions with available_externally linkage in the first place?
>
> 1. I knew how to write this pass; modifying clang would have required
> learning more.
> 2. It seems useful to be able to compile the runtime library to .bc
> with external functions, codegen the .o from that for the real runtime
> library, and then convert it to the available_externally form for use
> by application optimizers and JITs. A front-end flag would require
> compiling from C twice.
> 3. dgregor endorsed the idea of this patch, although I didn't mention
> the possibility of a clang flag.
>
> But let me know if an extra clang flag would be preferable. I'll
> probably wind up writing a standalone tool for Unladen instead of
> shaving that yak, but I wouldn't object strongly to dropping this
> patch.
>
> _______________________________________________
> llvm-commits mailing list
> llvm-commits at cs.uiuc.edu
> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>