Re: Bug in handling of CLOBBERS for cse_skip_blocks.

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

  In message <Pine.LNX.3.96.980915151112.767A-100000@jinks.home>you write:
  > 
  > There is a bug in handling of CLOBBERS when using -fcse-skip-blocks
  > (enabled by default in -O2). The bug can be reproduced under egcs 1.0.3a,
  > as well as 1.1b.
  > 
  > Here's a vastly simplified source, m68k-specific:
  > 
  > 
  > void*
  > f(void)
  > {
  >   void *cl;
  > 
  >   cl=(
  >        {
  > 	 register void* ret __asm__("d1");
  > 	 __asm__("/* d1 is set here */" : "=r"(ret));
  > 	 ret;
  >        }
  >      );
  >   if (cl)
  > 	__asm__("/* d0 and d1 are invalidated here */" : : : "d0", "d1");
  > 
  >   return cl;
  > }
[ ... ]
I've installed this patch to fix your bug:

        * cse.c (invalidate_skipped_block): Call invalidate_from_clobbers
        for each insn in the skipped block.

Index: cse.c
===================================================================
RCS file: /egcs/carton/cvsfiles/egcs/gcc/cse.c,v
retrieving revision 1.56
retrieving revision 1.57
diff -c -r1.56 -r1.57
*** cse.c	1998/12/29 11:36:16	1.56
--- cse.c	1998/12/30 23:35:49	1.57
***************
*** 8141,8146 ****
--- 8141,8147 ----
  	  invalidate_for_call ();
  	}
  
+       invalidate_from_clobbers (PATTERN (insn));
        note_stores (PATTERN (insn), invalidate_skipped_set);
      }
  }