Add llvm::function_ref (and a couple of uses of it), representing a type-erased reference to a callable object.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208025 91177308-0d34-0410-b5e6-96231b3b80d8

include/llvm/Support/CrashRecoveryContext.h

@@ -12,11 +12,13 @@
 
 #include <string>
 
+#include "llvm/ADT/STLExtras.h"
+
 namespace llvm {
 class StringRef;
 
 class CrashRecoveryContextCleanup;
-  
+
 /// \brief Crash recovery helper object.
 ///
 /// This class implements support for running operations in a safe context so
@@ -46,21 +48,10 @@ class CrashRecoveryContext {
   void *Impl;
   CrashRecoveryContextCleanup *head;
 
-  /// An adaptor to convert an arbitrary functor into a void(void*), void* pair.
-  template<typename T> struct FunctorAdaptor {
-    T Fn;
-    static void invoke(void *Data) {
-      return static_cast<FunctorAdaptor<T>*>(Data)->Fn();
-    }
-    typedef void Callback(void*);
-    Callback *fn() { return &invoke; }
-    void *arg() { return this; }
-  };
-
 public:
   CrashRecoveryContext() : Impl(nullptr), head(nullptr) {}
   ~CrashRecoveryContext();
-  
+
   void registerCleanup(CrashRecoveryContextCleanup *cleanup);
   void unregisterCleanup(CrashRecoveryContextCleanup *cleanup);
 
@@ -86,11 +77,9 @@ public:
   /// make as little assumptions as possible about the program state when
   /// RunSafely has returned false. Clients can use getBacktrace() to retrieve
   /// the backtrace of the crash on failures.
-  bool RunSafely(void (*Fn)(void*), void *UserData);
-  template<typename Functor>
-  bool RunSafely(Functor Fn) {
-    FunctorAdaptor<Functor> Adaptor = { Fn };
-    return RunSafely(Adaptor.fn(), Adaptor.arg());
+  bool RunSafely(function_ref<void()> Fn);
+  bool RunSafely(void (*Fn)(void*), void *UserData) {
+    return RunSafely([&]() { Fn(UserData); });
   }
 
   /// \brief Execute the provide callback function (with the given arguments) in
@@ -98,12 +87,10 @@ public:
   /// requested stack size).
   ///
   /// See RunSafely() and llvm_execute_on_thread().
+  bool RunSafelyOnThread(function_ref<void()>, unsigned RequestedStackSize = 0);
   bool RunSafelyOnThread(void (*Fn)(void*), void *UserData,
-                         unsigned RequestedStackSize = 0);
-  template<typename Functor>
-  bool RunSafelyOnThread(Functor Fn, unsigned RequestedStackSize = 0) {
-    FunctorAdaptor<Functor> Adaptor = { Fn };
-    return RunSafelyOnThread(Adaptor.fn(), Adaptor.arg(), RequestedStackSize);
+                         unsigned RequestedStackSize = 0) {
+    return RunSafelyOnThread([&]() { Fn(UserData); }, RequestedStackSize);
   }
 
   /// \brief Explicitly trigger a crash recovery in the current process, and