egcs and K6

[Jeffrey A Law]

  In message < 36E7BDD3.91BC3829@gwdg.de >you write:
  > I have a patch ready that I'll send to egcs-patches in a day or two, that
  > mostly adds spec entries for the k6 to i386.h.
  > 
  > What I do in specs is mostly defining k6 as well as i586 and pentium. The
  > reasoning being that few if any software tests for k6 (I intend to change
  > that :). Any objections to this ?
Not really.  Though I would recommend against defining i586 or pentium for
the k6.

I'd model the code around the stuff used to define __pentium__ and
__pentiumpro__ in CPP_CPU_DEFAULT_SPEC.


  > This is because I discovered to my horror
  > that gcc only defines i386 when called with -mcpu=k6. I also added k6/no-k6
  > together with descriptions to TARGET_SWITCHES.
What instructions does the k6 have that are not on the other x86 processors?
(aside from 3dnow!, which should have a switch unto itself).

  > What I haven't discovered up til now - and the real reason why I'm writing
  > to the list - is how is the TARGET_CPU_DEFAULT determined ? My guess is its
  > taken from the build host definition ?
See i386.h.  That provides the deafult.

Other files (freebsd.h for example) can override the default target cpu.

It can also be overridden by configure.in (search for target_cpu_default).

Note you may need an assignment before we can install the code.  Please review
http://www.cygnus.com/egcs/contribute.html and take appropriate action before
submitting your patch.

jeff