[Haskell-cafe] Possible floating point bug in GHC?
bugfact at gmail.com
Fri Apr 3 16:47:04 EDT 2009
Ouch, what a waste of time on my side :-(
This bugfix is not mentioned in the "notable bug fixes"
Since this is such a severe bug, I would recommend listing it :)
Anyway, I have a very small repro test case now. Will certainly test this
with GHC 6.10.2.
On Fri, Apr 3, 2009 at 10:35 PM, Ian Lynagh <igloo at earth.li> wrote:
> On Fri, Apr 03, 2009 at 10:10:17PM +0200, Peter Verswyvelen wrote:
> > I tried both precise and fast, but that did not help. Compiling to SSE2
> > fixed it, since that does not use a floating point stack I guess.
> You didn't say what version of GHC you are using, but it sounds like
> this might already be fixed in 6.10.2 by:
> Tue Nov 11 12:56:19 GMT 2008 Simon Marlow <marlowsd at gmail.com>
> * Fix to i386_insert_ffrees (#2724, #1944)
> The i386 native code generator has to arrange that the FPU stack is
> clear on exit from any function that uses the FPU. Unfortunately it
> was getting this wrong (and has been ever since this code was written,
> I think): it was looking for basic blocks that used the FPU and adding
> the code to clear the FPU stack on any non-local exit from the block.
> In fact it should be doing this on a whole-function basis, rather than
> individual basic blocks.
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