From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Mon, 23 May 2016 15:37:07 +0000 (-0400)
Subject: Fix: update debug message about weak-hidden symbols
X-Git-Tag: v2.7.5~24
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=490346239d3df64bd3cda9ad88714b578d55412a;p=lttng-ust.git

Fix: update debug message about weak-hidden symbols

We actually deal OK with compilers that treats weak-hidden symbols as
different addresses between compile units part of the same module.
Simply report this without statement on whether or not the compiler
producing this code is broken.

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---

diff --git a/liblttng-ust/tracepoint-internal.h b/liblttng-ust/tracepoint-internal.h
index 3cc95e56..70842382 100644
--- a/liblttng-ust/tracepoint-internal.h
+++ b/liblttng-ust/tracepoint-internal.h
@@ -51,6 +51,8 @@ static inline void tracepoint_synchronize_unregister(void)
 extern void init_tracepoint(void);
 extern void exit_tracepoint(void);
 
-void *lttng_ust_tp_check_weak_hidden(void);
+void *lttng_ust_tp_check_weak_hidden1(void);
+void *lttng_ust_tp_check_weak_hidden2(void);
+void *lttng_ust_tp_check_weak_hidden3(void);
 
 #endif /* _LTTNG_TRACEPOINT_INTERNAL_H */
diff --git a/liblttng-ust/tracepoint-weak-test.c b/liblttng-ust/tracepoint-weak-test.c
index e691fbb1..dad2ece0 100644
--- a/liblttng-ust/tracepoint-weak-test.c
+++ b/liblttng-ust/tracepoint-weak-test.c
@@ -17,10 +17,26 @@
  */
 
 /* Test compiler support for weak symbols with hidden visibility. */
-char __tracepoint_test_symbol[9] __attribute__((weak, visibility("hidden")));
+int __tracepoint_test_symbol1 __attribute__((weak, visibility("hidden")));
+void *__tracepoint_test_symbol2 __attribute__((weak, visibility("hidden")));
+struct {
+	char a[24];
+} __tracepoint_test_symbol3 __attribute__((weak, visibility("hidden")));
 
 __attribute__((visibility("hidden")))
-void *lttng_ust_tp_check_weak_hidden(void)
+void *lttng_ust_tp_check_weak_hidden1(void)
 {
-	return __tracepoint_test_symbol;
+	return &__tracepoint_test_symbol1;
+}
+
+__attribute__((visibility("hidden")))
+void *lttng_ust_tp_check_weak_hidden2(void)
+{
+	return &__tracepoint_test_symbol2;
+}
+
+__attribute__((visibility("hidden")))
+void *lttng_ust_tp_check_weak_hidden3(void)
+{
+	return &__tracepoint_test_symbol3;
 }
diff --git a/liblttng-ust/tracepoint.c b/liblttng-ust/tracepoint.c
index a594d73d..db588600 100644
--- a/liblttng-ust/tracepoint.c
+++ b/liblttng-ust/tracepoint.c
@@ -44,7 +44,11 @@
 #include "error.h"
 
 /* Test compiler support for weak symbols with hidden visibility. */
-char __tracepoint_test_symbol[9] __attribute__((weak, visibility("hidden")));
+int __tracepoint_test_symbol1 __attribute__((weak, visibility("hidden")));
+void *__tracepoint_test_symbol2 __attribute__((weak, visibility("hidden")));
+struct {
+	char a[24];
+} __tracepoint_test_symbol3 __attribute__((weak, visibility("hidden")));
 
 /* Set to 1 to enable tracepoint debug output */
 static const int tracepoint_debug;
@@ -814,10 +818,18 @@ int tracepoint_unregister_lib(struct lttng_ust_tracepoint * const *tracepoints_s
  */
 static void check_weak_hidden(void)
 {
-	DBG("Your compiler support for weak symbols with hidden visibility is %s",
-		__tracepoint_test_symbol == lttng_ust_tp_check_weak_hidden() ?
-			"OK" :
-			"BROKEN. Please upgrade or fix your compiler to use LTTng-UST tracepoints.");
+	DBG("Your compiler treats weak symbols with hidden visibility for integer objects as %s between compile units part of the same module.",
+		&__tracepoint_test_symbol1 == lttng_ust_tp_check_weak_hidden1() ?
+			"SAME address" :
+			"DIFFERENT addresses");
+	DBG("Your compiler treats weak symbols with hidden visibility for pointer objects as %s between compile units part of the same module.",
+		&__tracepoint_test_symbol2 == lttng_ust_tp_check_weak_hidden2() ?
+			"SAME address" :
+			"DIFFERENT addresses");
+	DBG("Your compiler treats weak symbols with hidden visibility for 24-byte structure objects as %s between compile units part of the same module.",
+		&__tracepoint_test_symbol3 == lttng_ust_tp_check_weak_hidden3() ?
+			"SAME address" :
+			"DIFFERENT addresses");
 }
 
 void init_tracepoint(void)