Re: minor code-quality regression vs. 2.95

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

  In message <20000413232918.J9184@wolery.cumb.org>you write:
  > On Thu, Apr 13, 2000 at 04:16:47PM -0500, Clinton Popetz wrote:
  > > On Wed, Apr 12, 2000 at 03:08:38PM -0700, Zack Weinberg wrote:
  > >  
  > > > I also can't figure out how we get from 'val / 512' to ix86_expand_bran
  > ch.
  > > > There's no divdi pattern, and the ashrdi patterns don't generate the
  > > > branch and addition.  It must be hiding somewhere in the machine
  > > > independent code, but I don't know where.
  > > 
  > > expand_divmod does this when branches are cheap.  
  > 
  > Hmm... expand_divmod calls do_cmp_and_jump, which looks like it would
  > be the appropriate place to teach GCC that DImode < 0 or >= 0 can be
  > done by looking only at the high word.  But when I do that (see patch
  > below), it doesn't help, because i386 has a cmpdi pattern.  This
  > seems silly to me... why not let the generic code synthesize it?
I believe Richard Kenner checked in a case to optimize this stuff a couple
days ago, possibly even based on your change.

jeff