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Re: Problem: delete_dead_jumptables and constant pool references



I wrote:
> Richard Henderson wrote:
> > On Fri, Sep 21, 2001 at 12:14:44AM +0200, Ulrich Weigand wrote:
> > > Sorry for the late reply; I finally got around to try this out.
> > > The patch below, implementing your suggestion, does indeed fix
> > > the problem I'm experiencing as well.
> > 
> > It's so late that it will be incorrect by tomorrow.  Jan has
> > a patch to change the behaviour of flow_delete_insn.
> 
> Oops, I didn't realize this patch was related.  Thanks for pointing
> this out; I'll redo the patch once Jan's is in ...

OK, after Jan's changes the only problem in delete_dead_jumptables
is the comparison of LABEL_NUSES against 0.  This fails if the
jumptable label was forced into the literal pool.  The following
patch fixed this by checking LABEL_NUSES against 1 if 
LABEL_PRESERVE_P is true, similar to what is done in 
propagate_block_delete_insn.

OK to apply?

ChangeLog:

        * flow.c (delete_dead_jumptables): Delete jumptable if
        the only reference is from the literal pool.


Index: gcc/flow.c
===================================================================
RCS file: /cvs/gcc/gcc/gcc/flow.c,v
retrieving revision 1.479
diff -c -p -r1.479 flow.c
*** flow.c	2001/09/21 12:55:13	1.479
--- flow.c	2001/09/24 13:59:54
*************** delete_dead_jumptables ()
*** 795,801 ****
      {
        next = NEXT_INSN (insn);
        if (GET_CODE (insn) == CODE_LABEL
! 	  && LABEL_NUSES (insn) == 0
  	  && GET_CODE (next) == JUMP_INSN
  	  && (GET_CODE (PATTERN (next)) == ADDR_VEC
  	      || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))
--- 795,801 ----
      {
        next = NEXT_INSN (insn);
        if (GET_CODE (insn) == CODE_LABEL
! 	  && LABEL_NUSES (insn) == LABEL_PRESERVE_P (insn)
  	  && GET_CODE (next) == JUMP_INSN
  	  && (GET_CODE (PATTERN (next)) == ADDR_VEC
  	      || GET_CODE (PATTERN (next)) == ADDR_DIFF_VEC))


-- 
  Dr. Ulrich Weigand
  weigand@informatik.uni-erlangen.de


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