From: Siddhesh Poyarekar <siddhesh@redhat.com>
Date: Tue, 3 Dec 2013 06:56:12 +0000 (+0530)
Subject: [BZ #16195] Fix build warnings from systemtap probes in non-systemtap configurations
X-Git-Tag: glibc-2.19~424
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=520d437b9455560d099fe6bd9664be1f9f76868b;p=thirdparty%2Fglibc.git

[BZ #16195] Fix build warnings from systemtap probes in non-systemtap configurations

Joseph pointed out in the bug report (and in an earlier thread) that
systemtap probes cause build time warnings like the following:

    ../sysdeps/ieee754/dbl-64/e_atan2.c:602:4: warning: the address of
    'p' will always evaluate as 'true' [-Waddress]

due to the fact that we're now passing non-weak variables to
LIBC_PROBE in the libm probes.  This happens only on configurations
that do not enable systemtap.  The macro definition of LIBC_PROBE in
this case only acts as a sanity checker to ensure that the number
parameters passed to LIBC_PROBE is equal to the argument count
parameter passed before it.  This can be done in a much simpler manner
by just adding a macro definition for each number of arguments.  I am
assuming here that we don't really want to bother with supporting
LIBC_PROBE with an indeterminate number of arguments and if there is a
need for a probe to have more data than what is currently supported (4
arguments), one could simply add an additional macro here.
---

diff --git a/ChangeLog b/ChangeLog
index de634b4d416..182051a7278 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,14 @@
+2013-12-03  Siddhesh Poyarekar  <siddhesh@redhat.com>
+
+	[BZ #16195]
+	* include/stap-probe.h [!USE_STAP_PROBE && !__ASSEMBLER__]
+	(LIBC_PROBE): Change definition to call STAP_PROBE* macros.
+	(STAP_PROBE0): New macro.
+	(STAP_PROBE1): Likewise.
+	(STAP_PROBE2): Likewise.
+	(STAP_PROBE3): Likewise.
+	(STAP_PROBE4): Likewise.
+
 2013-12-02  Ondřej Bílka  <neleai@seznam.cz>
 
 	* manual/llio.texi (Memory-mapped I/O): Add shm_open and shm_close.
diff --git a/NEWS b/NEWS
index e85b4c6e303..c431d72539d 100644
--- a/NEWS
+++ b/NEWS
@@ -19,8 +19,8 @@ Version 2.19
   15892, 15893, 15895, 15897, 15905, 15909, 15917, 15919, 15921, 15923,
   15939, 15948, 15963, 15966, 15985, 15988, 15997, 16032, 16034, 16036,
   16037, 16041, 16055, 16071, 16072, 16074, 16077, 16078, 16103, 16112,
-  16143, 16144, 16146, 16150, 16151, 16153, 16167, 16172, 16214, 16245,
-  16271.
+  16143, 16144, 16146, 16150, 16151, 16153, 16167, 16172, 16195, 16214,
+  16245, 16271.
 
 * The public headers no longer use __unused nor __block.  This change is to
   support compiling programs that are derived from BSD sources and use
diff --git a/include/stap-probe.h b/include/stap-probe.h
index 5f725562cbf..e2963506aad 100644
--- a/include/stap-probe.h
+++ b/include/stap-probe.h
@@ -61,13 +61,14 @@
 
 # ifndef __ASSEMBLER__
 /* Evaluate all the arguments and verify that N matches their number.  */
-#  define LIBC_PROBE(name, n, ...)					      \
-  do {									      \
-    _Bool __libc_probe_args[] = { 0, ## __VA_ARGS__ };			      \
-    _Bool __libc_probe_verify_n[(sizeof __libc_probe_args / sizeof (_Bool))   \
-                                == n + 1 ? 1 : -1];			      \
-    (void) __libc_probe_verify_n;					      \
-  } while (0)
+#define LIBC_PROBE(name, n, ...) STAP_PROBE##n (__VA_ARGS__)
+
+#define STAP_PROBE0()
+#define STAP_PROBE1(a1)
+#define STAP_PROBE2(a1, a2)
+#define STAP_PROBE3(a1, a2, a3)
+#define STAP_PROBE4(a1, a2, a3, a4)
+
 # else
 #  define LIBC_PROBE(name, n, ...)		/* Nothing.  */
 # endif