Re: patch to reduce register pressure from strength reduction

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

  In message <199901282315.XAA09469@phal.cygnus.co.uk>you write:
  > Indeed, I found that recombine_givs caused the use of an uninitialized
  > pseudo.
That was the symptom I saw when looking at genrecog's failure too.  Or more
correctly, there was an uninitialized stack slot.  Presumably for the pseudo
in question.

  > I did a SH cross torture test and an x86 native torture test.  I don't
  > like bootstraps for tests because it doesn't allow to rebuild the
  > compiler at will - if I can find the same bug with a c-torture failure,
  > it's usually much faster to find out what is wrong.
Well, for more complex changes like the loop stuff I would recommend a
bootstrap.  That may be policy in the near future to avoid these kinds of
problems.

ctorture is good for finding and killing a subset of bugs, particularly because
the tests are small and easy to understand.  However, that simplicity often
provides less coverage than a bootstrap.


  > I've made the following patch, which I am currently testing:
  > 
  > Wed Jan 27 23:39:53 1999  J"orn Rennecke <amylaar@cygnus.co.uk>
  > 
  > 	* loop.c (recombine_givs): Don't try to derive givs that have combined.
This is fine.  Please install it.

Thanks,
jeff