Your change of September 11, 1998

[Bernd Schmidt]

On Tue, 16 Jan 2001, Richard Henderson wrote:

> On Tue, Jan 16, 2001 at 07:26:19AM -0500, Richard Kenner wrote:
> >     Useful, yes.  Essential?  Maybe yes, maybe no, depending on reorg.
> >
> > And flow.
>
> No, I understand how flow works and it doesn't care.
>
> We scan backwards from the end of a block.  If we see a register used,
> and it had been dead, it becomes live.  If a register is either set or
> clobbered -- we do not care which -- it becomes dead.

But other passes care about the clobber/set distinction; or more precisely
about seeing side effects explicitly in rtl.  For example, build_insn_chain
in global.c (and other code in that file) relies on it.


Bernd