Displaying 2 results from an estimated 2 matches for "lowervselecttovectorshuffle".
2016 Aug 29
2
IR canonicalization: vector select or shufflevector?
x86 has also put a lot of effort into shuffle lowering...so much so that it
is its own life-form and brings most online codeviewer apps to their knees
when you try to open X86ISelLowering.cpp. :)
Given that:
1. There are at least 2 targets that lean towards 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. L...
2016 Aug 29
2
IR canonicalization: vector select or shufflevector?
I have a slight preference towards shufflevector, because it makes
sequences of shuffles, where only some of the shuffles can be converted
into selects (because the input and output vector sizes of the others don't
match) simpler to reason about.
I'm not sure this is a particularly good reason, though.
On Mon, Aug 29, 2016 at 8:19 AM, Philip Reames via llvm-dev <
llvm-dev at