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Re: dangerous cleverness? ppc int<->float conversions, subreg
- To: Joern Rennecke <amylaar at onetel dot net dot uk>
- Subject: Re: dangerous cleverness? ppc int<->float conversions, subreg
- From: Zack Weinberg <zack at codesourcery dot com>
- Date: Fri, 26 Oct 2001 12:24:47 -0700
- Cc: Richard Henderson <rth at redhat dot com>, gcc at gcc dot gnu dot org
- References: <20011024214846.B4612@codesourcery.com> <200110251529.QAA20521@meolyon.local>
On Thu, Oct 25, 2001 at 04:29:45PM +0100, Joern Rennecke wrote:
> > Unfortunately it doesn't bother disabling the FPU for tasks that claim
> > not to need it. (This is being taken up with the kernel developers.)
> So how about making gas recognize if fp is needed, and coding it somewhere
> in elf flags or similar? FWIW the SH gas alrweady has to do this, to keep
... keep what?
That may be another option, but I was told that even if the kernel can
be fixed, we want to avoid having the compiler generate floating point
behind the user's back, because in a realtime embedded OS you really
want to be sure task switches are cheap.
In addition to the block move issue, I need to figure out how to fix
the old varargs implementation and sjlj eh so they don't touch
floating point registers unless absolutely necessary. Clues in that
direction would be appreciated too.