[PATCH] D83245: [PowerPC][Power10] Exploit the xxsplti32dx instruction when lowering VECTOR_SHUFFLE.

[Lei Huang via Phabricator via llvm-commits]

lei added inline comments.


================
Comment at: llvm/lib/Target/PowerPC/PPCISelLowering.cpp:9791
+  SDValue VecShuffle(SVN, 0);
+  SDLoc dl(SVN);
+
----------------
`dl`->`DL`


================
Comment at: llvm/lib/Target/PowerPC/PPCISelLowering.cpp:9824
+  unsigned SplatSize = SplatBitSize / 8;
+  if (SplatSize > 4)
+    return SDValue();
----------------
no need for the tmp `SplatSize`
```
if ((SplatBitSize / 8) > 4)
```


================
Comment at: llvm/lib/Target/PowerPC/PPCISelLowering.cpp:9838
+      (((ShuffleMask[4] % 4 == 0) && (ShuffleMask[12] % 4 == 0)) &&
+       (ShuffleMask[4] > 15 && ShuffleMask[12] > 15))) // Case 1.
+    Index = DAG.getTargetConstant(IsLE ? 1 : 0, dl, MVT::i1);
----------------
There see to be alot of extra, unnecessary `()` here... since all these are `&&` I think alot of these can be removed.


================
Comment at: llvm/lib/Target/PowerPC/PPCISelLowering.cpp:9840
+    Index = DAG.getTargetConstant(IsLE ? 1 : 0, dl, MVT::i1);
+  else if ((ShuffleMask[4] == 4 && ShuffleMask[12] == 12) && // Case 2.
+           (((ShuffleMask[0] % 4 == 0) && (ShuffleMask[8] % 4 == 0)) &&
----------------
same.


================
Comment at: llvm/lib/Target/PowerPC/PPCISelLowering.cpp:9843
+            (ShuffleMask[0] > 15 && ShuffleMask[8] > 15)))
+    Index = DAG.getTargetConstant(IsLE ? 0 : 1, dl, MVT::i1);
+
----------------
I think you are missing:
```
else
  return SDValue();
```


================
Comment at: llvm/lib/Target/PowerPC/PPCInstrPrefix.td:49
+  SDTCisVec<1>, SDTCisInt<2>, SDTCisInt<3>
+]>;
+
----------------
nit: indentation?


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D83245/new/

https://reviews.llvm.org/D83245