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Re: Must-alias analysis
- From: "Richard Guenther" <richard dot guenther at gmail dot com>
- To: "Martin Schindewolf" <schindew at ira dot uka dot de>
- Cc: gcc at gcc dot gnu dot org
- Date: Thu, 23 Oct 2008 11:11:57 +0200
- Subject: Re: Must-alias analysis
- References: <490039E2.4040000@ira.uka.de>
On Thu, Oct 23, 2008 at 10:46 AM, Martin Schindewolf
<schindew@ira.uka.de> wrote:
> Hi all,
>
> how is the must-alias information represented in mainline?
> Is there something like DEF-USE chains for virtual operands?
> How can I access this kind of information and where should I look for some
> examples how to use it?
> Thank you very much!
There is only may-alias information explicitely represented, by virtue of the
virtual operands USE-DEF/DEF-USE chains. You have to verify must-alias
relation yourself, which is eased by several helper functions, most notable
get_ref_base_and_extent () which dissects a memory reference into a
base, offset range and access size. You can compare the base for equality
using the operand_equal_p function. For pointer bases you can also access
points-to information present in the SSA_NAME_PTR_INFO structure.
On the alias-improvements branch we hopefully will end up with more specific
interfaces to query must-alias information.
Richard.