CC register for x86-64 asm statements. Was: glibc: syscalls for x86-64

[Robert Dewar]

<<I agree.  There are few enough instructions that don't
clobber flags that there is often little benefit.
>>

There are actually many uses of retaining flags over instructions that
do not affect them, although few compilers really take advantage of this
(an interesting bit of history here is that the first IBM portable
computer -- the convertible -- was based on the Harris 80C88. This machine
had a bug that caused CVD to clobber flags. The only known piece of software
affected was the Realia COBOL compiler -- IBM asked us to change the 
compiler :-)