Prevent combine_instructions() from following non-existant LOG_LINKS

[Franz Sirl]

At 01:22 25.04.00, Jeffrey A Law wrote:
>   In message <200001261857.KAA27932@elmo.cygnus.com>you write:
>   > Hi Guys,
>   >
>   >   I ran into a problem with combine_instructions() when RTL checking
>   >   is enabled.  Sometimes it can try to combine an insn which has been
>   >   deleted and the RTL checking code compainins about an attempt to
>   >   access the LOG_LINKS of a NOTE which is not supposed to have such a
>   >   field.  (It does have one, because it once was an insn, but the RTL
>   >   checking code does not know this).  The patch below fixes this small
>   >   problem by tetsing to see if the insn is a NOTE before LOG_LINKS is
>   >   called.
>   >
>   >   OK to apply this patch ?
>   >
>   > Cheers
>   >     Nick
>   >
>   > 2000-01-25  Nick Clifton  <nickc@redhat.com>
>   >
>   >     * combine.c (combine_instructions): Do not try to combine a
>   >     sequence of insns when the second insn has been replaced by a
>   >     note.
>This is fine.  Go ahead and install it.
>
>Note that at some point we may be able to undo this change if we twiddle
>the auto-inc code in the right manner.  But until then I don't see a reason
>why we should continue triggering an enable-checking failure.

Nick, you forgot to update your patch before applying it, this breaks 
bootstrap. The appended copy&pasted patch fixes it. I can't apply from work 
though.

Franz.

Index: gcc/combine.c
===================================================================
RCS file: /cvs/gcc/egcs/gcc/combine.c,v
retrieving revision 1.124
diff -u -p -r1.124 combine.c
--- combine.c   2000/04/25 00:40:36     1.124
+++ combine.c   2000/04/25 08:52:45
@@ -658,7 +658,8 @@ combine_instructions (f, nregs)
                    nextlinks;
                    nextlinks = XEXP (nextlinks, 1))
                 if ((next = try_combine (insn, XEXP (links, 0),
-                                        XEXP (nextlinks, 0))) != 0)
+                                        XEXP (nextlinks, 0),
+                                        &new_direct_jump_p)) != 0)
                   goto retry;
             }