Subzero: Second attempt at fixing MacOS 10.6 build.

src/IceTLS.h

+//===- subzero/src/IceTLS.h - thread_local workaround -----------*- C++ -*-===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file defines macros for working around the lack of support for
+// thread_local in MacOS 10.6.  It assumes std::thread is written in
+// terms of pthread.  Define ICE_THREAD_LOCAL_HACK to enable the
+// pthread workarounds.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef SUBZERO_SRC_ICETLS_H
+#define SUBZERO_SRC_ICETLS_H
+
+#if defined(_MSC_VER)
+#define ICE_ATTRIBUTE_TLS __declspec(thread)
+#else // !_MSC_VER
+#define ICE_ATTRIBUTE_TLS thread_local
+#endif // !_MSC_VER
+
+// Defines 4 macros for unifying thread_local and pthread:
+//
+// ICE_TLS_DECLARE_FIELD(Type, FieldName): Declare a static
+// thread_local field inside the current class definition.  "Type"
+// needs to be a pointer type, such as int* or class Foo*.
+//
+// ICE_TLS_DEFINE_FIELD(Type, ClassName, FieldName): Define a static
+// thread_local field outside of its class definition.  The field will
+// ultimately be initialized to nullptr.
+//
+// ICE_TLS_INIT_FIELD(FieldName): Ensure the thread_local field is
+// properly initialized.  This is intended to be called from within a
+// static method of the field's class after main() starts (to ensure
+// that the pthread library is fully initialized) but before any uses
+// of ICE_TLS_GET_FIELD or ICE_TLS_SET_FIELD.
+//
+// ICE_TLS_GET_FIELD(Type, FieldName): Read the value of the static
+// thread_local field.  Must be done within the context of its class.
+//
+// ICE_TLS_SET_FIELD(FieldName, Value): Write a value into the static
+// thread_local field.  Must be done within the context of its class.
+
+// TODO(stichnot): Limit this define to only the platforms that
+// absolutely require it.  And ideally, eventually remove this hack
+// altogether.
+#define ICE_THREAD_LOCAL_HACK
+#ifdef ICE_THREAD_LOCAL_HACK
+
+// For a static thread_local field F of a class C, instead of
+// declaring and defining C::F, we create two static fields:
+//   static pthread_key_t F__key;
+//   static int F__dummy;
+//
+// The F__dummy field is just used to hold the result of the
+// pthread_key_create() call, which is executed as a static
+// initializer.  The F__key field is used as the argument to
+// pthread_getspecific() and pthread_setspecific().
+
+#include <pthread.h>
+
+#define ICE_TLS_DECLARE_FIELD(Type, FieldName)                                 \
+  typedef Type FieldName##__type;                                              \
+  static pthread_key_t FieldName##__key;                                       \
+  static int FieldName##__dummy
+#define ICE_TLS_DEFINE_FIELD(Type, ClassName, FieldName)                       \
+  pthread_key_t ClassName::FieldName##__key;                                   \
+  int ClassName::FieldName##__dummy = !!"Silly non-conforming compiler";
+#define ICE_TLS_INIT_FIELD(FieldName)                                          \
+  if (FieldName##__dummy)                                                      \
+  FieldName##__dummy = pthread_key_create(&FieldName##__key, nullptr)

[JF, 2015/01/25 23:05:05]

You should probably handle non-zero returns properly, especially EGAIN and
ENOMEM. I'd also rename "dummy" to "needs_initialization" or something.

Why the weird initialization and not just true?

[Jim Stichnoth, 2015/01/26 05:43:37]

Done, though I didn't feel like there's much reason to distinguish different
error codes.
Well, I started out initializing it to 1, then I thought maybe something more
nonzero-like like 12345, then maybe something more flamboyant like
0x1BadCafeBabe, then I finally decided to express my "true" feelings.  OK, I
came to my senses and went back to 1.

+#define ICE_TLS_GET_FIELD(FieldName)                                           \
+  (assert(FieldName##__dummy == 0),                                            \
+   static_cast<FieldName##__type>(pthread_getspecific(FieldName##__key)))
+#define ICE_TLS_SET_FIELD(FieldName, Value)                                    \
+  (assert(FieldName##__dummy == 0),                                            \
+   pthread_setspecific(FieldName##__key, (Value)))
+
+#else // !ICE_THREAD_LOCAL_HACK
+
+#define ICE_TLS_DECLARE_FIELD(Type, FieldName)                                 \
+  static ICE_ATTRIBUTE_TLS Type FieldName
+#define ICE_TLS_DEFINE_FIELD(Type, ClassName, FieldName)                       \
+  ICE_ATTRIBUTE_TLS Type ClassName::FieldName = nullptr
+#define ICE_TLS_INIT_FIELD(FieldName)
+#define ICE_TLS_GET_FIELD(FieldName) (FieldName)
+#define ICE_TLS_SET_FIELD(FieldName, Value) (FieldName = (Value))
+
+#endif // !ICE_THREAD_LOCAL_HACK
+
+#endif // SUBZERO_SRC_ICETLS_H