[llvm] [X86] TableGen-erate SDNode descriptions (PR #168421)

[Craig Topper via llvm-commits]

================
@@ -288,6 +391,8 @@ def X86xor_flag  : SDNode<"X86ISD::XOR",  SDTBinaryArithWithFlags,
 def X86and_flag  : SDNode<"X86ISD::AND",  SDTBinaryArithWithFlags,
                           [SDNPCommutative]>;
 
+/// LOCK-prefixed arithmetic read-modify-write instructions.
----------------
topperc wrote:

```suggestion
// LOCK-prefixed arithmetic read-modify-write instructions.
```

https://github.com/llvm/llvm-project/pull/168421