build report

[Jeffrey A Law]

  In message < 199802051938.OAA27614@oobleck.tn.cornell.edu >you write:
  > In general, your build requires a lot of late-model software.  It
  > would be nice to see the packages needed listed up front, boldly.  I
  > built the whole compiler and then discovered I needed a new binutils.
Err, I think the build instructions do tell you that you need a new
binutils for i686-pc-linux-gnu.

http://www.cygnus.com/egcs/install/specific.html

i?86-*-linux*
You will need binutils-2.8.1.0.15 or newer for exception handling to work. 

  > Also, a summary of new features compared to the current gcc release
  > would be great.  I tried putting -m686 in my BOOT_CFLAGS but it didn't
  > like it.  Ok, so how do you get the pentium and PPro scheduler?  That
  > kind of thing.
Look at the egcs-1.0.1 release page:

http://www.cygnus.com/egcs/egcs-1.0.1.html

It describes the new stuff in egcs-1.0.1 as well as comparing it to gcc-2.8.

  > Also also, there's this tantalyzing hint about Haifa.  Does it produce
  > *worse* code on any platform?
It could.  It requires tuning of the machine description  to more closely
match how the processor actually works -- many machine descriptions lied
about the processor's pipeline to try to get better performance out of
the old scheduler.

Also on register poor machines like the x86, the more aggressive scheduling
done by the haifa scheduler may increase register pressure and lead to
worse code.

  > I.e., is it unsafe to use it by default?
Nope.  1.0.1 has it on by default for the PA.  Current snapshots have it
on for the PA, rs6000/ppc and alpha -- those are the ports that have been
tuned to work with the haifa scheduler.

  > Is it related to improved scheduler support for 586 and 686?
  > There are about 5 lines in the various docs about it, and they just
  > talk about how to turn it on or not.  Is there a way to select it a
  > gcc runtime?
No, there's no way to select it at runtime; it's a configure time only
option.

jef