[PATCH] D20239: [Power9] Add codegen for VSX word insert/extract instructions

[Ehsan Amiri via llvm-commits]

amehsan added inline comments.

================
Comment at: lib/Target/PowerPC/PPCISelLowering.cpp:1566-1567
@@ +1565,4 @@
+
+  // If both vector operands for the shuffle are the same vector, the mask will
+  // contain only elements from the first one and the second one will be undef.
+  if (N->getOperand(1).isUndef()) {
----------------
How is this guaranteed?


Repository:
  rL LLVM

http://reviews.llvm.org/D20239