Displaying 3 results from an estimated 3 matches for "d22114".
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d2214
2016 Aug 28
2
IR canonicalization: vector select or shufflevector?
...in IR, which of these should we prefer?
Some backend / lowering differences for AArch64 and PPC are noted in:
https://llvm.org/bugs/show_bug.cgi?id=28530
https://llvm.org/bugs/show_bug.cgi?id=28531
x86 converts either form optimally in all cases I've looked at.
This question first came up in D22114 ( https://reviews.llvm.org/D22114 )
and is extended in D23886 ( https://reviews.llvm.org/D23886 ) with a
constant value example.
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2016 Aug 29
2
IR canonicalization: vector select or shufflevector?
...prefer?
> Some backend / lowering differences for AArch64 and PPC are noted in:
> https://llvm.org/bugs/show_bug.cgi?id=28530
> https://llvm.org/bugs/show_bug.cgi?id=28531
>
> x86 converts either form optimally in all cases I've looked at.
>
> This question first came up in D22114 ( https://reviews.llvm.org/D22114 )
> and is extended in D23886 ( https://reviews.llvm.org/D23886 ) with a
> constant value example.
>
>
>
> _______________________________________________
> LLVM Developers mailing listllvm-dev at lists.llvm.orghttp://lists.llvm.org/cgi-bin/mai...
2016 Aug 29
2
IR canonicalization: vector select or shufflevector?
...owards shuffle (Martin's comment
+ x86 uses lowerVSELECTtoVectorShuffle() for all cases like the example
posted here)
2. Size-changing shuffles are easier to reason about with other shuffles
(Michael's comment)
3. Insert/extract are easier to reason about with shuffles (Eli's comment
in D22114)
...we should probably go with shuffle as the canonical encoding. Like
Philip, I think the select is easier to read in IR (and mentally translate
to an x86 'blend'), but there's no other advantage for select?
I'll give this thread some more time before posting a patch...in case we...