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Re: Linux doesn't follow x86/x86-64 ABI wrt direction flag
On Mar 6, 2008, at 2:06 PM, Andi Kleen wrote:
On Thu, Mar 06, 2008 at 12:56:16PM -0800, H. Peter Anvin wrote:
Richard Guenther wrote:
A patched GCC IMHO makes only sense if it is always-on, yet
won't help in corner cases. And corner cases is exactly what
to care about. For this reason that we have this single release,
behaves "bad" is already a problem.
The option will help embedded vendors who can guarantee that it's
For very very low values of "help".
To be realistic it is very unlikely anybody will measure a difference
from a few more or a few less clds in a program. It's not that they're
They aren't? According to http://www.agner.org/optimize/instruction_tables.pdf
, they have a latency of 52 cycles on at least one popular x86 chip.