LLVM IR influence on compiler debugging

Adam Wilson flyboynw at gmail.com
Sat Jul 7 21:44:48 PDT 2012


On Sat, 07 Jul 2012 21:13:35 -0700, Jonathan M Davis <jmdavisProg at gmx.com>  
wrote:

> On Saturday, July 07, 2012 20:26:56 Adam Wilson wrote:
>> On Sat, 07 Jul 2012 19:33:22 -0700, Andrei Alexandrescu
>>
>> <SeeWebsiteForEmail at erdani.org> wrote:
>> > On 7/7/12 8:29 PM, Adam Wilson wrote:
>> >> Sure they complain, but they would complain harder if the generated  
>> code
>> >> was sub-optimal or had bugs in it. And I imagine that multiple hour
>> >> build times are more the exception than rule even in C++, my
>> >> understanding is that all 50mloc of Windows can compile overnight  
>> using
>> >> distributed compiling. Essentially, my argument is that for business
>> >> compilation time is something that can be attacked with money, where
>> >> code generation and perf bugs are not.
>> >
>> > I'm sorry, but I think you got that precisely backwards.
>> >
>> > Andrei
>>
>> Why is that?
>
> Well, considering that the general trend over the last ten years has  
> been to
> move to languages which focus on programmer productivity (including
> compilation speed) over those which focus on speed of execution, there's  
> a
> definite argument that programmers generally prefer stuff that makes  
> programming
> easier and faster over stuff that makes the program faster. There are  
> obviously
> exceptions, and there are some signs of things shifting (due to mobile  
> and
> whatnot), but that's the way that things have been trending for over a  
> decade.
>
> - Jonathan M Davis

I won't argue with this at all, I use C# after all. But there we shuffle  
the "backend" off to the JIT, so compilation is really more a translation  
to IR. IIRC this is how most of the popular productivity languages did it  
(Java, .NET, etc.).

It'd be an interesting research project to modify LDC to output IR only  
and run the IR later on an LLVM based VM and then see what kind of compile  
times you get...

-- 
Adam Wilson
IRC: LightBender
Project Coordinator
The Horizon Project
http://www.thehorizonproject.org/


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