ARM: Make "SMC" instructions conditional on new TrustZone architecture feature.

These instructions aren't universally available, but depend on a specific
extension to the normal ARM architecture (rather than, say, v6/v7/...) so a new
feature is appropriate.

This also enables the feature by default on A-class cores which usually have
these extensions, to avoid breaking existing code and act as a sensible
default.

llvm-svn: 179171
diff --git a/llvm/lib/Target/ARM/ARMSubtarget.h b/llvm/lib/Target/ARM/ARMSubtarget.h
index 5b5ee6a..038eb76 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.h
+++ b/llvm/lib/Target/ARM/ARMSubtarget.h
@@ -148,6 +148,9 @@
   /// precision.
   bool FPOnlySP;
 
+  /// HasTrustZone - if true, processor supports TrustZone security extensions
+  bool HasTrustZone;
+
   /// AllowsUnalignedMem - If true, the subtarget allows unaligned memory
   /// accesses for some types.  For details, see
   /// ARMTargetLowering::allowsUnalignedMemoryAccesses().
@@ -251,6 +254,7 @@
   bool hasVMLxForwarding() const { return HasVMLxForwarding; }
   bool isFPBrccSlow() const { return SlowFPBrcc; }
   bool isFPOnlySP() const { return FPOnlySP; }
+  bool hasTrustZone() const { return HasTrustZone; }
   bool prefers32BitThumb() const { return Pref32BitThumb; }
   bool avoidCPSRPartialUpdate() const { return AvoidCPSRPartialUpdate; }
   bool avoidMOVsShifterOperand() const { return AvoidMOVsShifterOperand; }