On Fri, 29 Jun 2001, Alan Cox wrote:
> > Here I have to disagree with you Alan. When you pass "-march=i686" to
> > gcc, you are _not_ saying "generate code for a CPUID family 6 CPU".
> > "-march=i686" actually means "target an Intel P6 family chip, given
> > what we currently know about them". The gcc info pages don't talk
>
> Which is fine. The Pentium Pro manual explicitly states that cmov may go
> away. So it is not based on what we know about the CPU, its based on not
> reading the documentation.
>
> It's a bug. -march=i6868 does not 'target an Intel P6 family chip, ...'
> It happens to work because the error in reading the docs was never triggered
> by intel removing cmov from a cpu as the reserved the right to do
Pedantically you may be right, but it's not a very useful interpretation of
the situation. Would it make you happier if -march=i686 was documented as
generating cmov instructions? IMO it's only a manual bug if at all.
Bernd
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This archive was generated by hypermail 2b29 : Sat Jun 30 2001 - 21:00:21 EST