[X86] truncateVectorWithPACK - fix outdated comment. NFC.

We perform PACKSS/PACKUS on AVX512 targets if the calling function wants to.

diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 1c6164c..a6bb415 100644 (file)
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -20270,7 +20270,7 @@ static SDValue truncateVectorWithPACK(unsigned Opcode, EVT DstVT, SDValue In,
          "Unexpected PACK opcode");
   assert(DstVT.isVector() && "VT not a vector?");
 
-  // Requires SSE2 but AVX512 has fast vector truncate.
+  // Requires SSE2 for PACKSS (SSE41 PACKUSDW is handled below).
   if (!Subtarget.hasSSE2())
     return SDValue();