[PATCH] D123386: [AArch64] Add lane moves to PerfectShuffle tables

[Sjoerd Meijer via Phabricator via llvm-commits]

SjoerdMeijer accepted this revision.
SjoerdMeijer added a comment.
This revision is now accepted and ready to land.

Looks reasonable.



================
Comment at: llvm/lib/Target/AArch64/AArch64ISelLowering.cpp:9715
 /// the specified operations to build the shuffle.
-static SDValue GeneratePerfectShuffle(unsigned PFEntry, SDValue LHS,
+static SDValue GeneratePerfectShuffle(unsigned ID, SDValue V1,
+                                      SDValue V2, unsigned PFEntry, SDValue LHS,
----------------
Can you say what V1 and V2 is, or give them some other names.


================
Comment at: llvm/lib/Target/AArch64/AArch64ISelLowering.cpp:9755
+      while (Elt > 0) {
+        ID /= 9;
+        Elt--;
----------------
Don't know what magic number 9 is, or generally what this is doing. But yeah, looking something up in a table, so am guessing something related to the number of items per table entry. There seems to be enough prior art of magic constants, so looks fine. 


CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D123386/new/

https://reviews.llvm.org/D123386