Use a bit of relaxed constexpr to make FeatureBitset costant intializable

This requires std::intializer_list to be a literal type, which it is
starting with C++14. The downside is that std::bitset is still not
constexpr-friendly so this change contains a re-implementation of most
of it.

Shrinks clang by ~60k.

llvm-svn: 369847

1 files changed, 1 insertions, 1 deletions

diff --git a/llvm/lib/Target/Hexagon/HexagonSubtarget.cpp b/llvm/lib/Target/Hexagon/HexagonSubtarget.cpp
index 761d7d7aa0b..6c706fea096 100644
--- a/llvm/lib/Target/Hexagon/HexagonSubtarget.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonSubtarget.cpp
@@ -119,7 +119,7 @@ HexagonSubtarget::initializeSubtargetDependencies(StringRef CPU, StringRef FS) {
 
   FeatureBitset Features = getFeatureBits();
   if (HexagonDisableDuplex)
-    setFeatureBits(Features.set(Hexagon::FeatureDuplex, false));
+    setFeatureBits(Features.reset(Hexagon::FeatureDuplex));
   setFeatureBits(Hexagon_MC::completeHVXFeatures(Features));
 
   return *this;