<div dir="ltr">I agree with your concern. However, both CUDA and OpenCL (two most popular users of addrspacecast I believe) support generic address space, and could benefit from this optimization Would we end up with duplicated code (at least one for CUDA one for opencl) if we put it in the back-end? <div>
<br></div><div>Jingyue</div></div><div class="gmail_extra"><br><br><div class="gmail_quote">On Mon, Mar 24, 2014 at 11:22 AM, Justin Holewinski <span dir="ltr"><<a href="mailto:jholewinski@nvidia.com" target="_blank">jholewinski@nvidia.com</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
The hard part would be making this optimization general enough to be
target-independent. Optimizing to non-zero address spaces may not
make sense for all targets (or even all future versions of PTX). I
agree that there should be an IR-level optimization for this, but
perhaps its too target-specific and should actually live in the
back-end.<div><div class="h5"><br>
<br>
<div>On 03/24/2014 01:05 PM, Jingyue Wu
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">Right. We are aware of this issue, and think it
should be addressed in the IR optimizer (similar to
InstCombineLoadCast and InstCombineStoreToCast) instead of
clang. Do you think this is an appropriate approach? Is this
optimization general enough to stay in the IR optimizer or
target-dependent?
<div>
<br>
</div>
<div>Jingyue</div>
</div>
<div class="gmail_extra"><br>
<br>
<div class="gmail_quote">On Mon, Mar 24, 2014 at 4:54 AM, Justin
Holewinski <span dir="ltr"><<a href="mailto:justin.holewinski@gmail.com" target="_blank">justin.holewinski@gmail.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div dir="ltr">Hi Jingyue,
<div><br>
</div>
<div>I committed the addrspacecast isel patterns to NVPTX.
Also, I wanted to point out that your changes in the
last test case in this patch (<a href="http://address-spaces.cu" target="_blank">address-spaces.cu</a>)
represent changes that may lead to performance
degradation. Specific address spaces should be used
whenever possible for loads/stores. Casting everything
to a generic address is still correct, but may lead to
additional indirections for the hardware.</div>
</div>
<div class="gmail_extra">
<div>
<div><br>
<br>
<div class="gmail_quote">On Fri, Mar 21, 2014 at 2:25
PM, Justin Holewinski <span dir="ltr"><<a href="mailto:jholewinski@nvidia.com" target="_blank">jholewinski@nvidia.com</a>></span>
wrote:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
<div>addrspacecast support in NVPTX is on my
todo list. I'll try to put something together
in the next few days.
<div>
<div><br>
<br>
On 3/21/14, 2:20 PM, Jingyue Wu wrote:<br>
</div>
</div>
</div>
<div>
<div>
<blockquote type="cite">
<div dir="ltr">Hi,
<div><br>
</div>
<div>Static local variables in CUDA can
be declared with address space
qualifiers, such as __shared__.
Therefore, the codegen needs to
potentially addrspacecast a static
local variable to the type expected by
its declaration. Peter did something
similar for global variables in
r157167. </div>
<div><br>
</div>
<div>All clang tests passed. </div>
<div><br>
</div>
<div>Justin: The NVPTX backend support
for addrspacecast seems not complete.
We can send you follow-up patches once
this one gets in. </div>
<div><br>
</div>
<div> Jingyue</div>
</div>
</blockquote>
<br>
<br>
</div>
</div>
<span><font color="#888888">
<pre cols="72">--
Thanks,
Justin Holewinski</pre>
<div>
<hr>
</div>
<div>This email message is for the sole use
of the intended recipient(s) and may
contain confidential information. Any
unauthorized review, use, disclosure or
distribution is prohibited. If you are
not the intended recipient, please contact
the sender by reply email and destroy all
copies of the original message. </div>
<div>
<hr>
</div>
</font></span></div>
</blockquote>
</div>
<br>
<br clear="all">
<div><br>
</div>
</div>
</div>
<span><font color="#888888">-- <br>
<br>
<div>Thanks,</div>
<div><br>
</div>
<div>Justin Holewinski</div>
</font></span></div>
</blockquote>
</div>
<br>
</div>
</blockquote>
<br>
</div></div></div>
</blockquote></div><br></div>