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

Differential Revision: http://reviews.llvm.org/D8542

llvm-svn: 233055

1 files changed, 12 insertions, 11 deletions

diff --git a/llvm/lib/MC/SubtargetFeature.cpp b/llvm/lib/MC/SubtargetFeature.cpp
index 587be5427aa..2740839cd99 100644
--- a/llvm/lib/MC/SubtargetFeature.cpp
+++ b/llvm/lib/MC/SubtargetFeature.cpp
@@ -150,12 +150,12 @@ std::string SubtargetFeatures::getString() const {
 /// feature, set it.
 ///
 static
-void SetImpliedBits(uint64_t &Bits, const SubtargetFeatureKV *FeatureEntry,
+void SetImpliedBits(FeatureBitset &Bits, const SubtargetFeatureKV *FeatureEntry,
                     ArrayRef<SubtargetFeatureKV> FeatureTable) {
   for (auto &FE : FeatureTable) {
     if (FeatureEntry->Value == FE.Value) continue;
 
-    if (FeatureEntry->Implies & FE.Value) {
+    if ((FeatureEntry->Implies & FE.Value).any()) {
       Bits |= FE.Value;
       SetImpliedBits(Bits, &FE, FeatureTable);
     }
@@ -166,12 +166,13 @@ void SetImpliedBits(uint64_t &Bits, const SubtargetFeatureKV *FeatureEntry,
 /// feature, clear it.
 ///
 static
-void ClearImpliedBits(uint64_t &Bits, const SubtargetFeatureKV *FeatureEntry,
+void ClearImpliedBits(FeatureBitset &Bits, 
+                      const SubtargetFeatureKV *FeatureEntry,
                       ArrayRef<SubtargetFeatureKV> FeatureTable) {
   for (auto &FE : FeatureTable) {
     if (FeatureEntry->Value == FE.Value) continue;
 
-    if (FE.Implies & FeatureEntry->Value) {
+    if ((FE.Implies & FeatureEntry->Value).any()) {
       Bits &= ~FE.Value;
       ClearImpliedBits(Bits, &FE, FeatureTable);
     }
@@ -180,8 +181,8 @@ void ClearImpliedBits(uint64_t &Bits, const SubtargetFeatureKV *FeatureEntry,
 
 /// ToggleFeature - Toggle a feature and returns the newly updated feature
 /// bits.
-uint64_t
-SubtargetFeatures::ToggleFeature(uint64_t Bits, StringRef Feature,
+FeatureBitset
+SubtargetFeatures::ToggleFeature(FeatureBitset Bits, StringRef Feature,
                                  ArrayRef<SubtargetFeatureKV> FeatureTable) {
 
   // Find feature in table.
@@ -191,7 +192,6 @@ SubtargetFeatures::ToggleFeature(uint64_t Bits, StringRef Feature,
   if (FeatureEntry) {
     if ((Bits & FeatureEntry->Value) == FeatureEntry->Value) {
       Bits &= ~FeatureEntry->Value;
-
       // For each feature that implies this, clear it.
       ClearImpliedBits(Bits, FeatureEntry, FeatureTable);
     } else {
@@ -212,13 +212,13 @@ SubtargetFeatures::ToggleFeature(uint64_t Bits, StringRef Feature,
 
 /// getFeatureBits - Get feature bits a CPU.
 ///
-uint64_t
+FeatureBitset
 SubtargetFeatures::getFeatureBits(StringRef CPU,
                                   ArrayRef<SubtargetFeatureKV> CPUTable,
                                   ArrayRef<SubtargetFeatureKV> FeatureTable) {
 
   if (CPUTable.empty() || FeatureTable.empty())
-    return 0;
+    return FeatureBitset();
 
 #ifndef NDEBUG
   for (size_t i = 1, e = CPUTable.size(); i != e; ++i) {
@@ -230,7 +230,8 @@ SubtargetFeatures::getFeatureBits(StringRef CPU,
           "CPU features table is not sorted");
   }
 #endif
-  uint64_t Bits = 0;                    // Resulting bits
+  // Resulting bits
+  FeatureBitset Bits;
 
   // Check if help is needed
   if (CPU == "help")
@@ -247,7 +248,7 @@ SubtargetFeatures::getFeatureBits(StringRef CPU,
 
       // Set the feature implied by this CPU feature, if any.
       for (auto &FE : FeatureTable) {
-        if (CPUEntry->Value & FE.Value)
+        if ((CPUEntry->Value & FE.Value).any())
           SetImpliedBits(Bits, &FE, FeatureTable);
       }
     } else {