Port-i386 archive

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index][Old Index]

Re: Sleazy FPU optimization

On Feb 11, 2008, at 11:44 AM, David Laight wrote:

On Mon, Feb 11, 2008 at 07:43:09PM +0100, Joerg Sonnenberger wrote:
On Mon, Feb 11, 2008 at 05:27:16PM +0000, Matthias Scheler wrote:
Linux 2.6.20 and above has an interesting optimization for lazy FPU
context saving:

We've been discussing whether or not it is worth to do lazy FPU context
saving at all. Most programs will use the FPU on i386 anyway, e.g. if
printf is used. I'm not sure it will actually help.

1) Why would using printf for integers need the fpu

Because of va_list processing.  gcc may need to save/move FP registers
into order to pass a va_list

Home | Main Index | Thread Index | Old Index