recursive rtl bug

[Jeffrey A Law]

  In message < Pine.LNX.4.10.9912131507270.8922-100000@balti.cygnus.co.uk >you wr
ite:
  > On Tue, 23 Nov 1999, Tom Truscott wrote:
  > 
  > > I reported this SEGV a while back, but alas it is still happening:
  > > GNU C version 2.96 19991122 (experimental) (i686-pc-linux-gnu)
  > > 
  > >  /* "gcc -O foo.c" gets a SEGV */
  > >  void foo(double bar[], double *zp, int n)
  > >  {
  > >     int i, j;
  > > 
  > >     i = 0;
  > >     for(j = 0; j < n; j++)
  > >     {
  > >        i += j+1;
  > >        bar[i] *= (1.0 + *zp);
  > >     }
  > >  }
  > > 
  > > Here is some rudimentary debugging that might help.
  > > A self-referent rtl is created, which can be trapped with:
  > 
  > Here's a patch to fix it.  The problem is that we're generating shared rtl
  > in combine.  Later, we substitute in one expression and the other one
  > gets magically changed as well.
  > 
  > Bernd
  > 
  > 	* combine.c (combine_simplify_rtx): Don't create shared rtl.
This is fine (including the other places where it needs to be fixed).  Please
install this change as well as the testcase.

Thanks,
jeff