[llvm-commits] [PATCH] Address Space Alias Analysis

[Justin Holewinski]

On Tue, Oct 11, 2011 at 6:34 PM, Sandeep Patel <deeppatel1987 at gmail.com>wrote:

> It seems like we could turn this on automatically if we ever see a use
> of a non-default address space.
>

I hesitate to do this since some back-ends may not have the property that
separate address spaces are entirely disjoint and cannot alias.  For PTX, we
currently have this property because we use address spaces as a way to
differentiate the different types of device memory.


>
> deep
>
> On Tue, Oct 11, 2011 at 3:08 PM, Justin Holewinski
> <justin.holewinski at gmail.com> wrote:
> > The attached patch provides a new alias analysis: Address Space Alias
> > Analysis.  This pass is off-by-default and has no impact on generated
> code
> > unless -asaa is provided to opt.
> > This analysis signals NoAlias for pointers in different address spaces.
>  The
> > primary target for this pass is GPU back-ends which use LLVM address
> spaces
> > as a means for differentiating memory types (on-chip shared, off-chip
> > global, etc.) and hence pointers in different address spaces cannot
> alias.
> >  For OpenCL code compiled with the PTX back-end, this improves
> performance
> > by over 2x in some of my test kernels due to LLVM using this alias
> > information to remove redundant loads.
> > Is this okay to commit?
> >
> > --
> >
> > Thanks,
> > Justin Holewinski
> >
> > _______________________________________________
> > llvm-commits mailing list
> > llvm-commits at cs.uiuc.edu
> > http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
> >
> >
>



-- 

Thanks,

Justin Holewinski
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