[runtime] Fix MONO_ARCH_ENABLE_MONO_LMF_VAR

Using MONO_ARCH_ENABLE_MONO_LMF_VAR requires that we have means of getting the address of a tls variable (which is always the case when using __thread, but not necessarily when using pthread). Make sure that using it is properly guarded.

In the future we might want to remove MONO_ARCH_ENABLE_LMF_VAR and always try to use a tls variable for the lmf. Additionally we should benchmark what combinations work best and stick to them on all platforms. (ex when using fast tls we might consider using lmf_get + lmf_set if possible, when using fallbacks we might always want to use the lmf_addr to void multiple calls, always use lmf_ir etc).


Commit migrated from mono/mono@da1e7bb

src/mono/mono/mini/mini-runtime.c

@@ -691,7 +691,7 @@ register_dyn_icall (gpointer func, const char *name, const char *sigstr, gboolea
 MonoLMF *
 mono_get_lmf (void)
 {
-#if defined(MONO_ARCH_ENABLE_MONO_LMF_VAR)
+#if defined(MONO_ARCH_ENABLE_MONO_LMF_VAR) && defined(HAVE_GET_TLS_ADDR)
 	return (MonoLMF *)mono_tls_get_lmf ();
 #else
 	MonoJitTlsData *jit_tls;
@@ -716,11 +716,11 @@ mono_get_lmf_addr (void)
 void
 mono_set_lmf (MonoLMF *lmf)
 {
-#if defined(MONO_ARCH_ENABLE_MONO_LMF_VAR)
+#if defined(MONO_ARCH_ENABLE_MONO_LMF_VAR) && defined(HAVE_GET_TLS_ADDR)
 	mono_tls_set_lmf (lmf);
-#endif
-
+#else
 	(*mono_get_lmf_addr ()) = lmf;
+#endif
 }
 
 MonoJitTlsData*
@@ -852,7 +852,15 @@ setup_jit_tls_data (gpointer stack_start, gpointer abort_func)
 
 	jit_tls->first_lmf = lmf;
 
-#if defined(MONO_ARCH_ENABLE_MONO_LMF_VAR)
+	/*
+	 * We can have 2 configurations for accessing lmf.
+	 * We can use only the tls_lmf_addr variable, which will store the address of
+	 * jit_tls->lmf, or, if we have MONO_ARCH_ENABLE_MONO_LMF_VAR enabled, we can
+	 * use both tls_lmf_addr and tls_lmf variables (in this case we need to have
+	 * means of getting the address of a tls variable; this can be done always
+	 * when using __thread or, on osx, even when using pthread)
+	 */
+#if defined(MONO_ARCH_ENABLE_MONO_LMF_VAR) && defined(HAVE_GET_TLS_ADDR)
 	/* jit_tls->lmf is unused */
 	mono_tls_set_lmf (lmf);
 	mono_set_lmf_addr (mono_tls_get_tls_addr (TLS_KEY_LMF));

src/mono/mono/utils/mono-tls.c

@@ -7,7 +7,6 @@
  * Copyright 2013 Xamarin, Inc (http://www.xamarin.com)
  */
 
-#include <config.h>
 #include <mono/utils/mach-support.h>
 
 #include "mono-tls.h"
@@ -34,9 +33,6 @@
  * wrappers and managed allocators, both of which are not aot-ed by default.
  * So far, we never supported inlined fast tls on full-aot systems.
  */
-#ifdef HAVE_KW_THREAD
-#define USE_KW_THREAD
-#endif
 
 #ifdef USE_KW_THREAD
 
@@ -270,13 +266,15 @@ mono_tls_get_tls_setter (MonoTlsKey key, gboolean name)
 gpointer
 mono_tls_get_tls_addr (MonoTlsKey key)
 {
+#ifdef HAVE_GET_TLS_ADDR
 	if (key == TLS_KEY_LMF) {
 #if defined(USE_KW_THREAD)
 		return &mono_tls_lmf;
 #elif defined(TARGET_MACH)
 		return mono_mach_get_tls_address_from_thread (pthread_self (), mono_tls_key_lmf);
 #endif
 	}
+#endif
 	/* Implement if we ever need for other targets/keys */
 	g_assert_not_reached ();
 	return NULL;

src/mono/mono/utils/mono-tls.h

@@ -12,6 +12,7 @@
 #ifndef __MONO_TLS_H__
 #define __MONO_TLS_H__
 
+#include <config.h>
 #include <glib.h>
 
 /* TLS entries used by the runtime */
@@ -27,6 +28,17 @@ typedef enum {
 	TLS_KEY_NUM = 6
 } MonoTlsKey;
 
+#ifdef HAVE_KW_THREAD
+#define USE_KW_THREAD
+#endif
+
+#if defined(USE_KW_THREAD)
+#define HAVE_GET_TLS_ADDR
+#elif defined(TARGET_MACH) && (defined(TARGET_X86) || defined(TARGET_AMD64))
+/* mono_mach_get_tls_address_from_thread is untested for arm/arm64 */
+#define HAVE_GET_TLS_ADDR
+#endif
+
 #ifdef HOST_WIN32
 
 #include <windows.h>