address comments

Author: FreddyLeaf

llvm/docs/ReleaseNotes.md

@@ -221,7 +221,7 @@ Changes to the X86 Backend
 
 * Supported ISA of `SM4(EVEX)`.
 
-* Support ISA of `MSR_IMM`.
+* Supported ISA of `MSR_IMM`.
 
 Changes to the OCaml bindings
 -----------------------------

llvm/test/MC/X86/msrimm-64-att.s

@@ -1,4 +1,8 @@
 // RUN: llvm-mc -triple x86_64 --show-encoding %s | FileCheck %s
+// RUN: not llvm-mc -triple i386 -show-encoding %s 2>&1 | FileCheck %s --check-prefix=ERROR
+
+// ERROR-COUNT-2: error:
+// ERROR-NOT: error:
 
 // CHECK: rdmsr $123, %r9
 // CHECK: encoding: [0xc4,0xc7,0x7b,0xf6,0xc1,0x7b,0x00,0x00,0x00]