Re: How to know if compiler is Safe?

[Jeffrey A Law <law at cygnus dot com>]

  In message <Pine.LNX.3.96.980610124308.8687A-100000@oto.dyn.ml.org>you write:
  > I'm new to egcs.  Currently, I'm using the egcs-1.0.3 binary distribution
  > from sunsite, and it appears to work fine, I've been compiling kernels and
  > other various things (with -O6 -mpentium). I'd like to use one of the
  > snapshots. But when I compile it and run the testsuite, there are
  > unexpected errors.  Should I worry about these?  How will I know if it's
  > safe to install, and use for general compilation?  Should I be getting no
  > unexpected errors?
It depends on exactly what errors you got.  We can't help you if
you don't give us the list of unexpected failures :-)

Some unexpected failures are normal on certain platforms.

  > And what do you guys think about pgcc?  It appears to
  > use the haifa flag when compiling.  Does it optimize much better than
  > egcs?  Sorry for all these questions, but they don't seem to be answered
  > on the FAQ.  ;-)
Using haifa on the x86 processors may or may not be a win; I'm not
sure if it's been throughly analyzed on those targets.

I'd be a little worried that haifa's more aggressive scheduling can
lengthen register lifetimes which has more effect on the x86 targets
than any other target which uses instruction scheduling.

pgcc generally optimizes better than egcs for specific (all?) x86
platforms.  Many of the changes are not appropriate for a compiler
that wants to work on many platforms like egcs.  The good news is
we are slowly trying to provide equivalent pgcc functionality in a
more maintainable and generally useful way.  It takes signifiant
time though :-)

jeff