[llvm-dev] llvm and clang are getting slower

[Bruno Cardoso Lopes via llvm-dev]

Hi,

> There is a possibility that r259673 could play a role here.
>
> For the buildSchedGraph() method, there is the -dag-maps-huge-region that
> has the default value of 1000. When I commited the patch, I was expecting
> people to lower this value as needed and also suggested this, but this has
> not happened. 1000 is very high, basically "unlimited".
>
> It would be interesting to see what results you get with e.g. -mllvm
> -dag-maps-huge-region=50. Of course, since this is a trade-off between
> compile time and scheduler freedom, some care should be taken before
> lowering this in trunk.

Indeed we hit this internally, filed a PR:
https://llvm.org/bugs/show_bug.cgi?id=26940

As a general comment on this thread and as mentioned by Mehdi, we care
a lot about compile time and we're looking forward to contribute more
in this area in the following months; by collecting compile time
testcases into a testsuite and publicly tracking results on those we
should be able to start a RFC on a tradeoff policy.

-- 
Bruno Cardoso Lopes
http://www.brunocardoso.cc