GHC 6.8.1 is impressive!

Ravi Nanavati ravi at
Fri Nov 9 08:34:23 EST 2007

On 11/9/07, Simon Peyton-Jones <simonpj at> wrote:
> | I just finished a running Bluespec's regression suite on a version of
> | our tools compiled with ghc 6.8.1. The results were impressive on two
> | fronts:
> |
> | 1. All of our tests (almost 14,000) had the same behavior as with ghc 6.6.1
> | 2. Our Haskell code was roughly 33% faster (relative to ghc 6.6.1). It
> | seems that pointer-tagging made a big difference for our code base
> | (since, if I'm reading the release notes correctly, constructor
> | specialization isn't in yet).
> |
> | We just wanted to take a moment to say that we were pleasantly
> | surprised by ghc 6.8.1
> Thanks for taking the time to let us know Ravi.
> Constructor specialisation (aka call-pattern specialisation) is in 6.8.1; try -O2 and see what difference that makes.  I'd be interested to know.

In that case, the 33% I cite above includes constructor
specialization, since we compile with -O2 anyway. I just wasn't sure
that it was in since it wasn't called out in the release notes. On
that topic, does anyone know a clever way to get a more detailed
changelog between 6.6.1 and 6.8.1? It would be useful for situations
like that when I'm curious about changes that didn't make the release


 - Ravi

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