Maybe this should be done upstream in LLVM, actually. Seems like work that
would be applicable to e.g. clang with LTO as well.
Tim Chevalier <[email protected]> wrote:
>On Fri, Nov 29, 2013 at 9:09 AM, Patrick Walton <[email protected]>
>wrote:
>> I shouldn't say that Rust has no problems with build times--it could
>always
>> be faster, and in particular the memory representations are
>inefficient,
>> particularly around ASTs--but when you actually run with `-Z
>time-passes`,
>> you'll see that the vast majority of the time for any
>reasonably-sized crate
>> is spent in LLVM. There isn't much we can do to make that faster by
>an order
>> of magnitude, other than to try to push on the parallel per-function
>> optimization and codegen work that is happening in some upstream
>branches.
>> Mergefunc, disabling exceptions, and the no-zeroing-out stuff that
>Niko is
>> doing would be nice, but they won't improve build times by an order
>of
>> magnitude.
>
>What about caching LLVM bitcode for individual Rust functions / items
>(using workcache, for example) and only recompiling those items whose
>dependencies have changed? Obviously this would be a lot of design and
>implementation work, and one would want to do the math to make sure
>it's likely to improve build performance, but offhand I can't see why
>it's not feasible.
>
>The scenario I'm thinking of is "add a debug! statement to one
>function, and only recompile the code for that function since its
>interface hasn't changed". In that case, only regenerating code for
>the changed function and not the entire crate should make a big
>difference.
>
>Cheers,
>Tim
>
>>
>> Patrick
>>
>> [1]:
>>
>https://groups.google.com/forum/#!topic/mozilla.dev.platform/WjcCfckml4A
>>
>>
>> _______________________________________________
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>> https://mail.mozilla.org/listinfo/rust-dev
>
>
>
>--
>Tim Chevalier * http://catamorphism.org/ * Often in error, never in
>doubt
>"If you are silent about your pain, they'll kill you and say you
>enjoyed it."
>-- Zora Neale Hurston
--
Sent from my Android phone with K-9 Mail. Please excuse my brevity.
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