[erlang-questions] hipe - erllvm: finished, quiet, or other?

[Felix Gallo]

Kostis, thanks for taking time from your vacation to answer. :)  I'm glad
to hear erllvm is still alive and kicking.  I did have trouble building it
on a few platforms with various llvm releases; I'll see if I can repeat and
distill the issues when I get a chance.

F.

On Wed, Jul 27, 2016 at 11:12 PM, Kostis Sagonas <kostis@REDACTED> wrote:

> On 07/15/2016 07:09 PM, Felix Gallo wrote:
>
>>
>> Both HiPE and erllvm seem pretty quiet these days; there's commentary
>> and work in mainline otp suggesting that erllvm is still under some kind
>> of development, but it's been a few years since the main erllvm page has
>> been updated, and I'm having difficulty getting a recent llvm to work
>> (which is not unusual, given that each llvm release involves breaking
>> changes, and they move pretty rapidly).
>>
>> Where's the bleeding edge on this?
>>
>
> First of all, just in case you did not know it, note that ErLLVM has been
> fully included in Erlang/OTP for a couple of years now, as an alternative
> backend to the native code compiler.  You can use it simply by specifying
> the compiler option {hipe, [to_llvm]} to the list of compiler options of
> the BEAM compiler.  However, the performance you can expect to get is not
> very much different than that of the vanilla HiPE compiler, and given that
> the compilation times are higher, there is probably not very much reason to
> prefer it over HiPE unless you really have some code that the LLVM compiler
> is good in optimizing.
>
> Both HiPE and ErLLVM are quite stable these days.  There is some
> development still going on, for example there have been many pull requests
> that made it into 19 and some that are still cooking on github, but the
> level of activity is not so high these days.
>
> Since the inclusion of ErLLVM in Erlang/OTP, we have not felt the need to
> update the erllvm page.  Also, unfortunately, we have not really been
> following the development of LLVM and consequently the erllvm compiler in
> Erlang/OTP releases in 18.x and prior do not work with recent LLVM
> versions.  But there has been quite a lot of activity during the first half
> of 2016 and, as far as we know, on x86_84, the ErLLVM code in 19.0 works OK
> with all LLVM versions >= 3.5, including the most recent one(s).  Please
> send a report if you have trouble using HiPE on some platform or the ErLLVM
> in 19 on x86_64.  It will be news to us.  (There are known issues with
> ErLLVM on x86, but these are due to bugs of LLVM.)
>
> Anyway, the bottomline is that we are still doing our best to support HiPE
> and ErLLVM by fixing bugs and doing performance improvements as we discover
> them,  But I would classify HiPE and ErLLVM in 19.0 as usable.
>
> Kostis
>
> PS. Apologies for the slow response; it's vacation time...
>
>
>
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