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Re: [PATCH v2] Target-specific limits on vector alignment
- From: "Ulrich Weigand" <uweigand at de dot ibm dot com>
- To: richard dot guenther at gmail dot com (Richard Guenther)
- Cc: rearnsha at arm dot com (Richard Earnshaw), gcc-patches at gcc dot gnu dot org (gcc-patches at gcc dot gnu dot org), hans-peter dot nilsson at axis dot com
- Date: Mon, 30 Jul 2012 16:42:20 +0200 (CEST)
- Subject: Re: [PATCH v2] Target-specific limits on vector alignment
Richard Guenther wrote:
> On Fri, Jul 27, 2012 at 5:24 PM, Ulrich Weigand <uweigand@de.ibm.com> wrote:
> > OK for mainline?
>
> Ok. Please add to the documentation that the default vector alignment
> has to be a power-of-two multiple of the default vector element alignment.
Committed, thanks. The documentation now reads:
+ "This hook can be used to define the alignment for a vector of type\n\
+ @var{type}, in order to comply with a platform ABI. The default is to\n\
+ require natural alignment for vector types. The alignment returned by\n\
+ this hook must be a power-of-two multiple of the default alignment of\n\
+ the vector element type.",
> You probably want to double-check vector_alignment_reachable_p as well
> which checks whether vector alignment can be reached by peeling off
> scalar iterations.
I've looked at the ARM implementation, and it still seems to correct
(and efficient) with vector alignment change (basically, unless the
element type is packed, everything is reachable).
Bye,
Ulrich
--
Dr. Ulrich Weigand
GNU Toolchain for Linux on System z and Cell BE
Ulrich.Weigand@de.ibm.com