From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jeffrey A Law <law@cygnus.com>
To: John Carr <jfc@mit.edu>
Cc: egcs@cygnus.com
Subject: Re: cse.c bug? 
Date: Mon, 09 Feb 1998 02:36:00 -0000
Message-id: <5899.887020715@hurl.cygnus.com>
References: <199802012043.PAA13035@jfc.>
X-SW-Source: 1998-02/msg00351.html

  In message < 199802012043.PAA13035@jfc. >you write:
  > 
  > I think there is a bug in the CSE code to scan skipped blocks.  It's
  > been about 5 years since I worked on this code and I can't remember
  > why invalidate_skipped_set ignores CLOBBERs, but I found a case where
  > it shouldn't.
  > 
  > On SPARC, in a sequence like
  > 	set cc
  > 	branch on cc
  > 	label
  > 	clobber cc
  > 	set cc
  > 	branch on cc
  > 
  > the second compare was being eliminated even though the CC was no
  > longer valid.  The clobber was in a PARALLEL.
  > 
  > Can anyone see where CLOBBER in a skipped block is supposed to be
  > handled?  If not, I suggest this patch.
Hmmm, your alias analysis changes removed a call to invalidate_from_clobbers:

        note_stores (PATTERN (insn), invalidate_skipped_set);
-       invalidate_from_clobbers (&skipped_writes_memory, PATTERN (insn));

Which might be the problem.  You might just need to add the call back
(without the skipped_writes_memory argument).

jeff