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Re: [PATCH/RFC] Start to use VIEW_CONVERT_EXPR more and start to fix PR 26069
- From: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- To: pinskia at physics dot uc dot edu
- Cc: gcc-patches at gcc dot gnu dot org
- Date: Mon, 04 Sep 2006 21:20:22 EDT
- Subject: Re: [PATCH/RFC] Start to use VIEW_CONVERT_EXPR more and start to fix PR 26069
- References: <1157415451.24185.114.camel@celery.andrew.com>
> 2) Have the gimplifier swap which side of a MODIFY_EXPR, the
> VIEW_CONVERT_EXPR is on. This helps because otherwise a in
> "VIEW_CONVERT_EXPR<int> a = b;" needs to be addressable.
> 3) Fix a bug in tree-ssa-operands which does not mark a in
> "VIEW_CONVERT <int> a = b;" as addressable.
I agree that (2) is worthwhile since V_C_E on the LHS is peculiar. However,
I don't understand the reference to being marked addressable. There's no
reason to mark the operand of V_C_E as addressable. In no way do we take
a pointer that can be used elsewhere. And the only time we're going to be
forcing it into memory is in the BLKmode case, when it's already in memory.
> The one question I have about 1 is should we ignore the aliasing set and
> always do this transformation even though we know we turn undefined code
> into defined code?
I'd say yes, ignore it.