ARM: Add Performance Monitor Extensions feature

Performance monitors, including a basic cycle counter, are an official
extension in the ARMv7 specification. This adds support for enabling and
disabling them, orthogonally from CPU selection.

rdar://problem/13939186

llvm-svn: 182602

3 files changed, 10 insertions, 1 deletions

diff --git a/llvm/lib/Target/ARM/ARM.td b/llvm/lib/Target/ARM/ARM.td
index 2d7470919dc..6b8dbb27239 100644
--- a/llvm/lib/Target/ARM/ARM.td
+++ b/llvm/lib/Target/ARM/ARM.td
@@ -59,6 +59,8 @@ def FeatureSlowFPBrcc : SubtargetFeature<"slow-fp-brcc", "SlowFPBrcc", "true",
                                          "FP compare + branch is slow">;
 def FeatureVFPOnlySP : SubtargetFeature<"fp-only-sp", "FPOnlySP", "true",
                           "Floating point unit supports single precision only">;
+def FeaturePerfMon : SubtargetFeature<"perfmon", "HasPerfMon", "true",
+                           "Enable support for Performance Monitor extensions">;
 def FeatureTrustZone : SubtargetFeature<"trustzone", "HasTrustZone", "true",
                           "Enable support for TrustZone security extensions">;
 
@@ -134,7 +136,7 @@ def HasV6T2Ops  : SubtargetFeature<"v6t2", "HasV6T2Ops", "true",
                                    [HasV6Ops, FeatureThumb2]>;
 def HasV7Ops    : SubtargetFeature<"v7", "HasV7Ops", "true",
                                    "Support ARM v7 instructions",
-                                   [HasV6T2Ops]>;
+                                   [HasV6T2Ops, FeaturePerfMon]>;
 
 //===----------------------------------------------------------------------===//
 // ARM Processors supported.
diff --git a/llvm/lib/Target/ARM/ARMSubtarget.cpp b/llvm/lib/Target/ARM/ARMSubtarget.cpp
index c7d97437906..455fe1abe9a 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.cpp
+++ b/llvm/lib/Target/ARM/ARMSubtarget.cpp
@@ -106,6 +106,7 @@ void ARMSubtarget::initializeEnvironment() {
   HasRAS = false;
   HasMPExtension = false;
   FPOnlySP = false;
+  HasPerfMon = false;
   HasTrustZone = false;
   AllowsUnalignedMem = false;
   Thumb2DSP = false;
diff --git a/llvm/lib/Target/ARM/ARMSubtarget.h b/llvm/lib/Target/ARM/ARMSubtarget.h
index d01316511c4..bc5af96c606 100644
--- a/llvm/lib/Target/ARM/ARMSubtarget.h
+++ b/llvm/lib/Target/ARM/ARMSubtarget.h
@@ -148,6 +148,11 @@ protected:
   /// precision.
   bool FPOnlySP;
 
+  /// If true, the processor supports the Performance Monitor Extensions. These
+  /// include a generic cycle-counter as well as more fine-grained (often
+  /// implementation-specific) events.
+  bool HasPerfMon;
+
   /// HasTrustZone - if true, processor supports TrustZone security extensions
   bool HasTrustZone;
 
@@ -254,6 +259,7 @@ public:
   bool hasVMLxForwarding() const { return HasVMLxForwarding; }
   bool isFPBrccSlow() const { return SlowFPBrcc; }
   bool isFPOnlySP() const { return FPOnlySP; }
+  bool hasPerfMon() const { return HasPerfMon; }
   bool hasTrustZone() const { return HasTrustZone; }
   bool prefers32BitThumb() const { return Pref32BitThumb; }
   bool avoidCPSRPartialUpdate() const { return AvoidCPSRPartialUpdate; }