Stealing ideas from the latest GCC release

[Jan-Willem Maessen]

On Thu, Mar 22, 2012 at 5:09 PM, Johan Tibell <johan.tibell at gmail.com>wrote:

> Hi all,
>
> While looking at the GCC 4.7 [1] release notes I saw something that's
> perhaps worth stealing. Taken from the release notes:
>
>    The inter-procedural constant propagation pass has been rewritten. It
>    now performs generic function specialization. For example when
>    compiling the following:
>
>    void foo(bool flag)
>    {
>      if (flag)
>        ... do something ...
>      else
>        ... do something else ...
>    }
>    void bar (void)
>    {
>      foo (false);
>      foo (true);
>      foo (false);
>      foo (true);
>      foo (false);
>      foo (true);
>    }
>
>
>    GCC will now produce two copies of foo. One with flag being true,
>    while other with flag being false. This leads to performance
>    improvements previously possibly only by inlining all calls. Cloning
>    causes a lot less code size growth.
>

Wait, I thought this is essentially what constructor specialization does?
 I suppose we might then keep around the old body.  Or will these behave
differently in the presence of, say, different constant Int arguments?

-Jan-Willem Maessen
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.haskell.org/pipermail/glasgow-haskell-users/attachments/20120322/eee95191/attachment.htm>