use reserved spelling for inline assembly

Use the reserved spelling for `asm` as it is a non-standard compiler
extension.

Rather than trying to enumerate the user label prefix on the various
targets, rely on the compiler.  The GNU compilers define
`__USER_LABEL_PREFIX__` to "_" as appropriate.  In the case that you are
using a non-GNU compiler, it is possible to specify the macro according
to your target.  This simplifies and unifies the code.

Signed-off-by: Daniel A. Steffen <[email protected]>

Author: compnerd

os/object_private.h

@@ -86,7 +86,7 @@
 #endif
 #define OS_OBJECT_OBJC_CLASS_DECL(name) \
 		extern void *OS_OBJECT_CLASS_SYMBOL(name) \
-				asm(OS_OBJC_CLASS_RAW_SYMBOL_NAME(OS_OBJECT_CLASS(name)))
+				__asm__(OS_OBJC_CLASS_RAW_SYMBOL_NAME(OS_OBJECT_CLASS(name)))
 #else
 #define OS_OBJECT_HAVE_OBJC1 0
 #define OS_OBJECT_HAVE_OBJC2 0

src/block.cpp

@@ -109,11 +109,7 @@ extern "C" {
 // The compiler hides the name of the function it generates, and changes it if
 // we try to reference it directly, but the linker still sees it.
 extern void DISPATCH_BLOCK_SPECIAL_INVOKE(void *)
-#if defined(__linux__) || defined(__FreeBSD__)
-		asm("___dispatch_block_create_block_invoke");
-#else
-		asm("____dispatch_block_create_block_invoke");
-#endif
+		__asm__(OS_STRINGIFY(__USER_LABEL_PREFIX__) "___dispatch_block_create_block_invoke");
 void (*_dispatch_block_special_invoke)(void*) = DISPATCH_BLOCK_SPECIAL_INVOKE;
 }
 

src/init.c

@@ -897,7 +897,7 @@ void
 _dispatch_temporary_resource_shortage(void)
 {
 	sleep(1);
-	asm("");  // prevent tailcall
+	__asm__ __volatile__("");  // prevent tailcall
 }
 
 void *

src/introspection.c

@@ -447,7 +447,7 @@ dispatch_introspection_hooks_s _dispatch_introspection_hook_callouts_enabled = {
 
 #define DISPATCH_INTROSPECTION_INTERPOSABLE_HOOK(h) \
 		DISPATCH_EXPORT void _dispatch_introspection_hook_##h(void) \
-		asm("_dispatch_introspection_hook_" #h); \
+		__asm__("_dispatch_introspection_hook_" #h); \
 		void _dispatch_introspection_hook_##h(void) {}
 
 #define DISPATCH_INTROSPECTION_INTERPOSABLE_HOOK_CALLOUT(h, ...)\

src/object_internal.h

@@ -50,7 +50,7 @@
 #if USE_OBJC
 #define DISPATCH_OBJC_CLASS_DECL(name) \
 		extern void *DISPATCH_CLASS_SYMBOL(name) \
-				asm(DISPATCH_CLASS_RAW_SYMBOL_NAME(name))
+				__asm__(DISPATCH_CLASS_RAW_SYMBOL_NAME(name))
 #endif
 
 // define a new proper class
@@ -65,7 +65,7 @@
 		}; \
 		OS_OBJECT_EXTRA_VTABLE_DECL(name, name) \
 		extern const struct name##_vtable_s OS_OBJECT_CLASS_SYMBOL(name) \
-				asm(OS_OBJC_CLASS_RAW_SYMBOL_NAME(OS_OBJECT_CLASS(name)))
+				__asm__(OS_OBJC_CLASS_RAW_SYMBOL_NAME(OS_OBJECT_CLASS(name)))
 
 #if OS_OBJECT_SWIFT3
 #define OS_OBJECT_INTERNAL_CLASS_DECL(name, super, ...) \
@@ -101,7 +101,7 @@
 		struct name##_s; \
 		OS_OBJECT_EXTRA_VTABLE_DECL(name, super) \
 		extern const struct super##_vtable_s OS_OBJECT_CLASS_SYMBOL(name) \
-				asm(OS_OBJC_CLASS_RAW_SYMBOL_NAME(OS_OBJECT_CLASS(name)))
+				__asm__(OS_OBJC_CLASS_RAW_SYMBOL_NAME(OS_OBJECT_CLASS(name)))
 
 #define DISPATCH_SUBCLASS_DECL(name, super) \
 		OS_OBJECT_SUBCLASS_DECL(dispatch_##name, super)

src/source.c

@@ -1220,7 +1220,7 @@ _dispatch_source_timer_telemetry(dispatch_source_t ds, dispatch_clock_t clock,
 	if (_dispatch_trace_timer_configure_enabled() ||
 			_dispatch_source_timer_telemetry_enabled()) {
 		_dispatch_source_timer_telemetry_slow(ds, clock, values);
-		asm(""); // prevent tailcall
+		__asm__ __volatile__ (""); // prevent tailcall
 	}
 }