Don't delete REG_UNUSED

[Andreas Schwab]

Jeffrey A Law <law@hurl.cygnus.com> writes:

|> I went and looked at Andreas's testcase, and I don't see where/how he should
|> have ever had a REG_UNUSED note for the "mod" part of the single divmod insn
|> in the testcase since both results are used (the divmod is inside a loop and
|> the mod part is used by the next loop iteration.

There are two divmod insn, one where mod is unused, the other where div is
unused (the compiler did not combine them for whatever reason).  Only the
one where the mod is unused makes a problem, because the m68k cannot
compute the mod without computing the div, and the constraints in the
[u]divmodsi4 pattern makes sure that there is no conflict for the div part
(which must match one of the inputs).

-- 
Andreas Schwab                                      "And now for something
schwab@issan.cs.uni-dortmund.de                      completely different"
schwab@gnu.org