GHC 8.2 generated code faster than 8.0 but slower than 7.10

[Harendra Kumar]

https://ghc.haskell.org/trac/ghc/ticket/14072

8.2.1 is (marginally) better than 7.8.4 on this benchmark, so I guess 8.4
can be better than 7.10.3.

-harendra

On 1 August 2017 at 15:42, Simon Peyton Jones <simonpj at microsoft.com> wrote:

> Thanks.  Could you open a Trac ticket, and explain carefully how to
> reproduce your results?
>
>
>
> Surely 8.4 should be faster than 7.10!
>
>
>
> Simon
>
>
>
> *From:* ghc-devs [mailto:ghc-devs-bounces at haskell.org] *On Behalf Of *Harendra
> Kumar
> *Sent:* 01 August 2017 10:46
> *To:* ghc-devs at haskell.org
> *Subject:* GHC 8.2 generated code faster than 8.0 but slower than 7.10
>
>
>
> Unicode normalization library (https://github.com/harendra-
> kumar/unicode-transforms
> <https://na01.safelinks.protection.outlook.com/?url=https%3A%2F%2Fgithub.com%2Fharendra-kumar%2Funicode-transforms&data=04%7C01%7Csimonpj%40microsoft.com%7Cea675f49b17b45582c5708d4d8c22226%7C72f988bf86f141af91ab2d7cd011db47%7C1%7C0%7C636371775684809111%7CUnknown%7CVW5rbm93bnx7IlYiOiIwLjAuMDAwMCIsIlAiOiJXaW4zMiIsIkFOIjoiT3RoZXIifQ%3D%3D%7C-1&sdata=4YlXVWqT4DKYHpgUcq9YF%2BiX2xH%2BLAHgI4GFCGt6zwg%3D&reserved=0>)
> shows around 10% improvement with GHC 8.2.1 when compared to GHC 8.0.1,
> across most benchmarks. However, it is still somewhat slower when compared
> to GHC 7.10.3. Here are some results:
>
>
>
> GHC 7.10.3:
>
> benchmarking unicode-transforms-text/NFD/English
> time                 4.823 ms   (4.765 ms .. 4.902 ms)
>
> benchmarking unicode-transforms-text/NFD/Devanagari
> time                 16.46 ms   (16.24 ms .. 16.78 ms)
>
>
> GHC 8.0.1
>
>
> benchmarking unicode-transforms-text/NFD/English
> time                 6.330 ms   (6.232 ms .. 6.439 ms)
>
> benchmarking unicode-transforms-text/NFD/Devanagari
> time                 18.02 ms   (17.77 ms .. 18.22 ms)
>
> GHC 8.2.1
>
>
> benchmarking unicode-transforms-text/NFD/English
> time                 5.659 ms   (5.594 ms .. 5.740 ms)
>
> benchmarking unicode-transforms-text/NFD/Devanagari
> time                 16.48 ms   (16.30 ms .. 16.69 ms)
>
>
>
> This library has been optimized with an objective to match or better (in
> some cases it is better) the performance of the equivalent ICU C++ library
> (compare only decompose normalization). Some of the last hurdles to match
> the best case of C++ were in the code generated by GHC. Also, for GHC 7.10
> LLVM generated code is significantly faster than GHC native, I have not yet
> tested LLVM backend with 8.2.1 so not sure if that too has improved
> correspondingly.
>
>
>
> I just wanted to share these results with the GHC devs. Thanks for all the
> good work. Also wondering which specific changes might have caused this
> improvement.
>
>
>
> Thanks,
>
> Harendra
>
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