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Re: [PATCH] Fix 14844/15459/21608: Forward-propagate casts that will collapse
- From: Richard Henderson <rth at redhat dot com>
- To: Richard Guenther <rguenth at tat dot physik dot uni-tuebingen dot de>
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Tue, 24 May 2005 13:21:51 -0700
- Subject: Re: [PATCH] Fix 14844/15459/21608: Forward-propagate casts that will collapse
- References: <429309A3.2050000@tat.physik.uni-tuebingen.de>
On Tue, May 24, 2005 at 01:01:55PM +0200, Richard Guenther wrote:
> + /* We require that the SSA_NAME holding the result of the NOP_EXPR
> + be used only once. That may be overly conservative in that we
> + could propagate into multiple uses. However, that would effectively
> + be un-cseing the NOP_EXPR, which is probably not what we want. */
Yes we do want to uncse the NOP_EXPR -- it's suppoesd to be a no-op,
after all. Forwprop is not the place for this optimization.
r~