Use std::bitset for SubtargetFeatures

Previously, subtarget features were a bitfield with the underlying type being uint64_t. 
Since several targets (X86 and ARM, in particular) have hit or were very close to hitting this bound, switching the features to use a bitset.
No functional change.

The first two times this was committed (r229831, r233055), it caused several buildbot failures. 
At least some of the ARM and MIPS ones were due to gcc/binutils issues, and should now be fixed.

llvm-svn: 237234

3 files changed, 35 insertions, 12 deletions

diff --git a/llvm/include/llvm/MC/MCInstrDesc.h b/llvm/include/llvm/MC/MCInstrDesc.h
index c74d1c3fd86..e23a8b61de5 100644
--- a/llvm/include/llvm/MC/MCInstrDesc.h
+++ b/llvm/include/llvm/MC/MCInstrDesc.h
@@ -144,8 +144,9 @@ public:
   const uint16_t *ImplicitUses; // Registers implicitly read by this instr
   const uint16_t *ImplicitDefs; // Registers implicitly defined by this instr
   const MCOperandInfo *OpInfo;  // 'NumOperands' entries about operands
-  uint64_t
+  FeatureBitset
       DeprecatedFeatureMask; // Feature bits that this is deprecated on, if any
+
   // A complex method to determine is a certain is deprecated or not, and return
   // the reason for deprecation.
   bool (*ComplexDeprecationInfo)(MCInst &, MCSubtargetInfo &, std::string &);
@@ -168,7 +169,7 @@ public:
                          std::string &Info) const {
     if (ComplexDeprecationInfo)
       return ComplexDeprecationInfo(MI, STI, Info);
-    if ((DeprecatedFeatureMask & STI.getFeatureBits()) != 0) {
+    if ((STI.getFeatureBits() & DeprecatedFeatureMask).any()) {
       // FIXME: it would be nice to include the subtarget feature here.
       Info = "deprecated";
       return true;
diff --git a/llvm/include/llvm/MC/MCSubtargetInfo.h b/llvm/include/llvm/MC/MCSubtargetInfo.h
index 3984a1fb21b..1778a6d13fb 100644
--- a/llvm/include/llvm/MC/MCSubtargetInfo.h
+++ b/llvm/include/llvm/MC/MCSubtargetInfo.h
@@ -42,7 +42,7 @@ class MCSubtargetInfo {
   const InstrStage *Stages;            // Instruction itinerary stages
   const unsigned *OperandCycles;       // Itinerary operand cycles
   const unsigned *ForwardingPaths;     // Forwarding paths
-  uint64_t FeatureBits;                // Feature bits for current CPU + FS
+  FeatureBitset FeatureBits;           // Feature bits for current CPU + FS
 
 public:
   void InitMCSubtargetInfo(StringRef TT, StringRef CPU, StringRef FS,
@@ -67,13 +67,13 @@ public:
 
   /// getFeatureBits - Return the feature bits.
   ///
-  uint64_t getFeatureBits() const {
+  const FeatureBitset& getFeatureBits() const {
     return FeatureBits;
   }
 
   /// setFeatureBits - Set the feature bits.
   ///
-  void setFeatureBits(uint64_t FeatureBits_) { FeatureBits = FeatureBits_; }
+  void setFeatureBits(FeatureBitset& FeatureBits_) { FeatureBits = FeatureBits_; }
 
   /// InitMCProcessorInfo - Set or change the CPU (optionally supplemented with
   /// feature string). Recompute feature bits and scheduling model.
@@ -84,11 +84,15 @@ public:
 
   /// ToggleFeature - Toggle a feature and returns the re-computed feature
   /// bits. This version does not change the implied bits.
-  uint64_t ToggleFeature(uint64_t FB);
+  FeatureBitset ToggleFeature(uint64_t FB);
 
   /// ToggleFeature - Toggle a feature and returns the re-computed feature
-  /// bits. This version will also change all implied bits.
-  uint64_t ToggleFeature(StringRef FS);
+  /// bits. This version does not change the implied bits.
+  FeatureBitset ToggleFeature(const FeatureBitset& FB);
+
+  /// ToggleFeature - Toggle a set of features and returns the re-computed
+  /// feature bits. This version will also change all implied bits.
+  FeatureBitset ToggleFeature(StringRef FS);
 
   /// getSchedModelForCPU - Get the machine model of a CPU.
   ///
diff --git a/llvm/include/llvm/MC/SubtargetFeature.h b/llvm/include/llvm/MC/SubtargetFeature.h
index 6f195d7be99..6a631ffe79b 100644
--- a/llvm/include/llvm/MC/SubtargetFeature.h
+++ b/llvm/include/llvm/MC/SubtargetFeature.h
@@ -21,11 +21,29 @@
 #include "llvm/ADT/ArrayRef.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/Support/DataTypes.h"
+#include <bitset>
 
 namespace llvm {
   class raw_ostream;
   class StringRef;
 
+// A container class for subtarget features.
+// This is convenient because std::bitset does not have a constructor
+// with an initializer list of set bits.
+const unsigned MAX_SUBTARGET_FEATURES = 64;
+class FeatureBitset : public std::bitset<MAX_SUBTARGET_FEATURES> {
+public:
+  // Cannot inherit constructors because it's not supported by VC++..
+  FeatureBitset() : bitset() {}
+
+  FeatureBitset(const bitset<MAX_SUBTARGET_FEATURES>& B) : bitset(B) {}
+
+  FeatureBitset(std::initializer_list<unsigned> Init) : bitset() {
+    for (auto I = Init.begin() , E = Init.end(); I != E; ++I)
+      set(*I);
+  }
+};
+
 //===----------------------------------------------------------------------===//
 ///
 /// SubtargetFeatureKV - Used to provide key value pairs for feature and
@@ -34,8 +52,8 @@ namespace llvm {
 struct SubtargetFeatureKV {
   const char *Key;                      // K-V key string
   const char *Desc;                     // Help descriptor
-  uint64_t Value;                       // K-V integer value
-  uint64_t Implies;                     // K-V bit mask
+  FeatureBitset Value;                  // K-V integer value
+  FeatureBitset Implies;                // K-V bit mask
 
   // Compare routine for std::lower_bound
   bool operator<(StringRef S) const {
@@ -82,11 +100,11 @@ public:
 
   /// ToggleFeature - Toggle a feature and returns the newly updated feature
   /// bits.
-  uint64_t ToggleFeature(uint64_t Bits, StringRef String,
+  FeatureBitset ToggleFeature(FeatureBitset Bits, StringRef String,
                          ArrayRef<SubtargetFeatureKV> FeatureTable);
 
   /// Get feature bits of a CPU.
-  uint64_t getFeatureBits(StringRef CPU,
+  FeatureBitset getFeatureBits(StringRef CPU,
                           ArrayRef<SubtargetFeatureKV> CPUTable,
                           ArrayRef<SubtargetFeatureKV> FeatureTable);