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 several times this was committed (e.g. r229831, r233055), it caused several buildbot failures.
Apparently the reason for most failures was both clang and gcc's inability to deal with large numbers (> 10K) of bitset constructor calls in tablegen-generated initializers of instruction info tables. 
This should now be fixed.

llvm-svn: 238192

1 files changed, 2 insertions, 2 deletions

diff --git a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
index 53758a0e046..84bb092fa28 100644
--- a/llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
+++ b/llvm/lib/Target/ARM/MCTargetDesc/ARMMCCodeEmitter.cpp
@@ -51,10 +51,10 @@ public:
   ~ARMMCCodeEmitter() override {}
 
   bool isThumb(const MCSubtargetInfo &STI) const {
-    return (STI.getFeatureBits() & ARM::ModeThumb) != 0;
+    return STI.getFeatureBits()[ARM::ModeThumb];
   }
   bool isThumb2(const MCSubtargetInfo &STI) const {
-    return isThumb(STI) && (STI.getFeatureBits() & ARM::FeatureThumb2) != 0;
+    return isThumb(STI) && STI.getFeatureBits()[ARM::FeatureThumb2];
   }
   bool isTargetMachO(const MCSubtargetInfo &STI) const {
     Triple TT(STI.getTargetTriple());