[ORC-RT] Introduce a ORC_RT_JIT_DISPATCH_TAG macro.

This macro can be used to define tag variables for use with jit-dispatch.

Author: lhames

compiler-rt/lib/orc/common.h

@@ -17,6 +17,12 @@
 #include "compiler.h"
 #include <type_traits>
 
+/// This macro should be used to define tags that will be associated with
+/// handlers in the JIT process, and call can be used to define tags f
+#define ORC_RT_JIT_DISPATCH_TAG(X) \
+extern "C" char X; \
+char X = 0;
+
 /// Opaque struct for external symbols.
 struct __orc_rt_Opaque {};
 

compiler-rt/lib/orc/macho_platform.cpp

@@ -25,14 +25,9 @@ using namespace __orc_rt;
 using namespace __orc_rt::macho;
 
 // Declare function tags for functions in the JIT process.
-extern "C" char __orc_rt_macho_get_initializers_tag;
-char __orc_rt_macho_get_initializers_tag = 0;
-
-extern "C" char __orc_rt_macho_get_deinitializers_tag;
-char __orc_rt_macho_get_deinitializers_tag = 0;
-
-extern "C" char __orc_rt_macho_symbol_lookup_tag;
-char __orc_rt_macho_symbol_lookup_tag = 0;
+ORC_RT_JIT_DISPATCH_TAG(__orc_rt_macho_get_initializers_tag)
+ORC_RT_JIT_DISPATCH_TAG(__orc_rt_macho_get_deinitializers_tag)
+ORC_RT_JIT_DISPATCH_TAG(__orc_rt_macho_symbol_lookup_tag)
 
 // eh-frame registration functions.
 // We expect these to be available for all processes.