[4Walter&Andrei] D is 40 times slower. We need a new language feature!

[H. S. Teoh via Digitalmars-d]

On Sat, May 20, 2017 at 12:00:37PM +0000, 9il via Digitalmars-d wrote:
> On Saturday, 20 May 2017 at 11:47:32 UTC, John Colvin wrote:
> > On Saturday, 20 May 2017 at 11:34:55 UTC, 9il wrote:
> > > On Saturday, 20 May 2017 at 11:30:54 UTC, John Colvin wrote:
> > > > [...]
> > > 
> > > I just found that new LLVM solves this issue (and was very
> > > surprised).
> > > The reason that ndslice <=v0.6.1 was so slow is LDC Issue 2121.
> > > I have added workaround in [2], it is v0.6.2.
> > > 
> > > [1] https://github.com/ldc-developers/ldc/issues/2121
> > > [2] https://github.com/libmir/mir-algorithm/pull/41
> > 
> > What's surprising about it? Thinking very simplistically (I don't
> > know how it actually works), if inlining happened first then surely
> > the later optimisation stages wouldn't have a problem detecting the
> > necessary loop invariants and hoisting them out.
> 
> It did not work before. I did similar benchmarks a year ago.

I don't think this warrants a language change.  It's an implementation
issue, specifically, an optimizer issue. Optimizers can always be
refined and improved further.


T

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