Eliminating static destructor for the BitCodeErrorCategory by converting to a ManagedStatic.

[beanz]

Summary

This is part of the overall goal of removing static initializers from LLVM.

[chandlerc]

Looks good with a small tweak below...

lib/Bitcode/Reader/BitcodeReader.cpp

3508 ↗

(On Diff #13884)

Since we can't rely on MSVC's thread safe function local statics we have to use a ManagedStatic here... but once we do, on non MSVC we pay the once-init cost twice.

I would just make these globals (sadly) until we only rely on MSVC versions with support for killing managed static entirely.

[beanz]

Something more like this?

[chandlerc]

Yep.

Closed by commit rL218149 (authored by cbieneman).

llvm/trunk/lib/Bitcode/Reader/BitcodeReader.cpp

 #include "llvm/IR/LLVMContext.h"
 #include "llvm/IR/Module.h"
 #include "llvm/IR/OperandTraits.h"
 #include "llvm/IR/Operator.h"
 #include "llvm/Support/DataStream.h"
 #include "llvm/Support/MathExtras.h"
 #include "llvm/Support/MemoryBuffer.h"
 #include "llvm/Support/raw_ostream.h"
+#include "llvm/Support/ManagedStatic.h"
+
 using namespace llvm;
 
 enum {
   SWITCH_INST_MAGIC = 0x4B5 // May 2012 => 1205 => Hex
 };
 
 std::error_code BitcodeReader::materializeForwardReferencedFunctions() {
   if (WillMaterializeAllForwardRefs)
std::string message(int IE) const override {
     case BitcodeError::InvalidValue:
       return "Invalid value";
     }
     llvm_unreachable("Unknown error type!");
   }
 };
 }
 
+static ManagedStatic<BitcodeErrorCategoryType> ErrorCategory;
+
 const std::error_category &llvm::BitcodeErrorCategory() {
-  static BitcodeErrorCategoryType O;
-  return O;
+  return *ErrorCategory;
 }
 
 //===----------------------------------------------------------------------===//
 // External interface
 //===----------------------------------------------------------------------===//
 
 /// \brief Get a lazy one-at-time loading module from bitcode.
 ///