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<div class="">On Jul 1, 2015, at 2:44 PM, David Majnemer <<a href="mailto:david.majnemer@gmail.com" class="">david.majnemer@gmail.com</a>> wrote:</div>
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<div class="gmail_quote">On Tue, Jun 30, 2015 at 9:34 AM, Justin Holewinski <span dir="ltr" class="">
<<a href="mailto:jholewinski@nvidia.com" target="_blank" class="">jholewinski@nvidia.com</a>></span> wrote:<br class="">
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> On Jun 26, 2015, at 4:20 AM, Chandler Carruth <<a href="mailto:chandlerc@gmail.com" class="">chandlerc@gmail.com</a>> wrote:<br class="">
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> This doesn't seem like the right approach at all.<br class="">
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> I don't think we want to use cost heuristics to dictate the canonical form in the IR. It makes the canonicalization *much* more complex and hard to manage.<br class="">
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</span>I agree. I would prefer not to mix the concepts of legality and performance here.<br class="">
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> I think that NVPTX should either change the datalayout to make i64 illegal (and that seems reasonable for instcombine to respect, but that would for example mean it would be an *absolute* decision, not a cost decision) or you'll need to do a late transform
to narrow the operations as much as possible.<br class="">
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I don’t see how we could remove i64 as a legal type in NVPTX. Our pointer size is 64-bit, so we need a container for pointers.<br class="">
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<div class="">I think other folks are doing (or would like to be doing) this sort of thing: <a href="http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-June/087248.html" class="">http://lists.cs.uiuc.edu/pipermail/llvmdev/2015-June/087248.html</a></div>
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<div>It’s a tricky situation. 64-bit pointers are legal in PTX, so defining and using them is the correct thing to do. Performance, on the other hand, is another matter.</div>
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> <a href="https://urldefense.proofpoint.com/v2/url?u=http-3A__reviews.llvm.org_D10750&d=AwMGaQ&c=8hUWFZcy2Z-Za5rBPlktOQ&r=mQ4LZ2PUj9hpadE3cDHZnIdEwhEBrbAstXeMaFoB9tg&m=Ilnfn1e53IOBToHq00YM322uXbqZ3IOVyjtuVXTgQlk&s=eBvbFsXGzFluGHKMMhXzt3XdLlY9qSCrSsa7w-b2yGU&e=" rel="noreferrer" target="_blank" class="">
http://reviews.llvm.org/D10750</a><br class="">
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