[NFC] Update documentation for AtomicCmpXchgInst

Fix bz#42325

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@363914 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/include/llvm/IR/Instructions.h b/include/llvm/IR/Instructions.h
index 337578c49e01459ee8cb7543087269b6d3767c5d..215ce45c7b758ae208f2a44cc01a816247677a59 100644 (file)
--- a/include/llvm/IR/Instructions.h
+++ b/include/llvm/IR/Instructions.h
@@ -521,9 +521,11 @@ private:
 //                                AtomicCmpXchgInst Class
 //===----------------------------------------------------------------------===//
 
-/// an instruction that atomically checks whether a
+/// An instruction that atomically checks whether a
 /// specified value is in a memory location, and, if it is, stores a new value
-/// there.  Returns the value that was loaded.
+/// there. The value returned by this instruction is a pair containing the
+/// original value as first element, and an i1 indicating success (true) or
+/// failure (false) as second element.
 ///
 class AtomicCmpXchgInst : public Instruction {
   void Init(Value *Ptr, Value *Cmp, Value *NewVal,