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Re: [PATCH] Fix PR tree-optimization/18184 (pointer mode conversions ignored)
- From: "Ulrich Weigand" <weigand at i1 dot informatik dot uni-erlangen dot de>
- To: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- Cc: weigand at i1 dot informatik dot uni-erlangen dot de, gcc-patches at gcc dot gnu dot org
- Date: Wed, 27 Oct 2004 21:30:42 +0200 (CEST)
- Subject: Re: [PATCH] Fix PR tree-optimization/18184 (pointer mode conversions ignored)
Richard Kenner wrote:
> + && TYPE_MODE (inner_type) == TYPE_MODE (outer_type)
> Don't you also have to compare TYPE_REF_CAN_ALIAS_ALL in all three places too?
I'm not sure. Conversions between different modes need to be preserved
as we actually need to generate code to implement the conversion.
I don't know what the semantics of a conversion from a pointer with
TYPE_REF_CAN_ALIAS_ALL to an equivalent pointer type without that
flag is (or vice versa). There's certainly no code generation involved;
and I don't even know for sure whether the TYPE_REF_CAN_ALIAS_ALL flag
needs to be preserved in that situation ...
Do you have an example where this matters?
Dr. Ulrich Weigand