Re: i386 FP comparsion bug (and sollution)

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

  In message <19981030102448.60179@atrey.karlin.mff.cuni.cz>you write:
  > >   > This usually works well.
  > >   > Problem is, that reg-stack pass should emit some swap/mov?f patterns
  > >   > between condition and jump.
  > > "should"?  Or do you mean "could"?
  > Well according of my knowedge "should" = "could" so I really don't know :)
I think you wanted "could" :-)  Substitute "could" in your sentence and it
would be equivalent to "sometimes reg-stack emits a swap/mov insn between a cc0
setter and cc0 user".

  > But reg-stack actually emits them sometimes.
That sounds like a major bug to me.  For cc0 machines like the x86, nothing
is allowed to come between a cc0 setter and cc0 user.

  > Yes, it is bug. But why do not turn it to feature?
Because that is not how cc0 is designed to work.  It is a core and fundamental
design decision that a cc0 setter and cc0 user must not be separated.

We could change this fundamental design concept.  But that does not mean we
should change this fundamental design concept.  Even if it allows better code
in some cases.

jeff