[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/ARMSubtarget.h b/llvm/lib/Target/ARM/ARMSubtarget.h
index d5f0b59..efa3196 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.h
+++ b/llvm/lib/Target/ARM/ARMSubtarget.h
@@ -201,6 +201,9 @@
   /// HasTrustZone - if true, processor supports TrustZone security extensions
   bool HasTrustZone;
 
+  /// Has8MSecExt - if true, processor supports ARMv8-M Security Extensions
+  bool Has8MSecExt;
+
   /// HasCrypto - if true, processor supports Cryptography extensions
   bool HasCrypto;
 
@@ -366,6 +369,7 @@
   bool isFPOnlySP() const { return FPOnlySP; }
   bool hasPerfMon() const { return HasPerfMon; }
   bool hasTrustZone() const { return HasTrustZone; }
+  bool has8MSecExt() const { return Has8MSecExt; }
   bool hasZeroCycleZeroing() const { return HasZeroCycleZeroing; }
   bool prefers32BitThumb() const { return Pref32BitThumb; }
   bool avoidCPSRPartialUpdate() const { return AvoidCPSRPartialUpdate; }