[ARM] Add ARMv8-M security extension instructions to ARMv8-M Baseline/Mainline

This patch was originally committed as r257883, but was reverted due to windows
failures. The cause of these failures has been fixed under r258677, hence
re-committing the original patch.

llvm-svn: 258681
diff --git a/llvm/lib/Target/ARM/ARM.td b/llvm/lib/Target/ARM/ARM.td
index e02815e..dad4232 100644
--- a/llvm/lib/Target/ARM/ARM.td
+++ b/llvm/lib/Target/ARM/ARM.td
@@ -89,6 +89,8 @@
                            "Enable support for Performance Monitor extensions">;
 def FeatureTrustZone : SubtargetFeature<"trustzone", "HasTrustZone", "true",
                           "Enable support for TrustZone security extensions">;
+def Feature8MSecExt : SubtargetFeature<"8msecext", "Has8MSecExt", "true",
+                          "Enable support for ARMv8-M Security Extensions">;
 def FeatureCrypto : SubtargetFeature<"crypto", "HasCrypto", "true",
                           "Enable support for Cryptography extensions",
                           [FeatureNEON]>;
@@ -394,6 +396,7 @@
                                                        FeatureDB,
                                                        FeatureHWDiv,
                                                        FeatureV7Clrex,
+                                                       Feature8MSecExt,
                                                        FeatureAcquireRelease,
                                                        FeatureMClass]>;
 
@@ -402,6 +405,7 @@
                                                        FeatureNoARM,
                                                        FeatureDB,
                                                        FeatureHWDiv,
+                                                       Feature8MSecExt,
                                                        FeatureAcquireRelease,
                                                        FeatureMClass]>;