Re: [PATCH] Tiny -fssa-ccp fix

[Richard Henderson <rth at redhat dot com>]

On Tue, Mar 05, 2002 at 04:15:10PM -0700, law@redhat.com wrote:
> It seems to me this should be fixed by updating the def-use chains at the
> end of ssa_fast_dce.

But it _has_ been removed from the def-use chains.  That's why
we got a NULL.

Look at the code in ssa_ccp_substitute_constants:

  for (i = FIRST_PSEUDO_REGISTER; i < VARRAY_SIZE (ssa_definition); i++)

If we're going to iterate over all register numbers, it's hardly
surprising that we'll come across one that isn't used anymore.

Or are you saying that we should have removed all traces that the
register ever existed, by reseting the latticevalue to UNDEFINED
and whatever else is needed?


r~