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, 7 insertions, 6 deletions

diff --git a/llvm/lib/Target/AArch64/Utils/AArch64BaseInfo.h b/llvm/lib/Target/AArch64/Utils/AArch64BaseInfo.h
index 0545329a583..71b84246953 100644
--- a/llvm/lib/Target/AArch64/Utils/AArch64BaseInfo.h
+++ b/llvm/lib/Target/AArch64/Utils/AArch64BaseInfo.h
@@ -313,9 +313,9 @@ struct SysAlias {
   uint16_t Encoding;
   FeatureBitset FeaturesRequired;
 
-  SysAlias (const char *N, uint16_t E) : Name(N), Encoding(E) {};
-  SysAlias (const char *N, uint16_t E, FeatureBitset F) :
-    Name(N), Encoding(E), FeaturesRequired(F) {};
+  constexpr SysAlias(const char *N, uint16_t E) : Name(N), Encoding(E) {}
+  constexpr SysAlias(const char *N, uint16_t E, FeatureBitset F)
+      : Name(N), Encoding(E), FeaturesRequired(F) {}
 
   bool haveFeatures(FeatureBitset ActiveFeatures) const {
     return (FeaturesRequired & ActiveFeatures) == FeaturesRequired;
@@ -326,9 +326,10 @@ struct SysAlias {
 
 struct SysAliasReg : SysAlias {
   bool NeedsReg;
-  SysAliasReg(const char *N, uint16_t E, bool R) : SysAlias(N, E), NeedsReg(R) {};
-  SysAliasReg(const char *N, uint16_t E, bool R, FeatureBitset F) : SysAlias(N, E, F),
-    NeedsReg(R) {};
+  constexpr SysAliasReg(const char *N, uint16_t E, bool R)
+      : SysAlias(N, E), NeedsReg(R) {}
+  constexpr SysAliasReg(const char *N, uint16_t E, bool R, FeatureBitset F)
+      : SysAlias(N, E, F), NeedsReg(R) {}
 };
 
 namespace AArch64AT{