X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=lib%2Fbitfield.h;h=42521f2e3f6741826ea9a74cc5d49a89786559fc;hb=5daaccef9d7dc530b9cb31993192255ee7c72926;hp=f748696ada911163014ec9cad4f4f0abf33ff6c1;hpb=b81caadf2d255e8e9f83aa3fa3652bdd013d7c6a;p=lttng-modules.git

diff --git a/lib/bitfield.h b/lib/bitfield.h
index f748696a..42521f2e 100644
--- a/lib/bitfield.h
+++ b/lib/bitfield.h
@@ -26,6 +26,26 @@
 #error "bitfield.h requires the compiler representation of signed integers to be two's complement."
 #endif
 
+/*
+ * _bt_is_signed_type() willingly generates comparison of unsigned
+ * expression < 0, which is always false. Silence compiler warnings.
+ */
+#ifdef __GNUC__
+# define _BT_DIAG_PUSH			_Pragma("GCC diagnostic push")
+# define _BT_DIAG_POP			_Pragma("GCC diagnostic pop")
+
+# define _BT_DIAG_STRINGIFY_1(x)	#x
+# define _BT_DIAG_STRINGIFY(x)		_BT_DIAG_STRINGIFY_1(x)
+
+# define _BT_DIAG_IGNORE(option)	\
+	_Pragma(_BT_DIAG_STRINGIFY(GCC diagnostic ignored option))
+# define _BT_DIAG_IGNORE_TYPE_LIMITS	_BT_DIAG_IGNORE("-Wtype-limits")
+#else
+# define _BT_DIAG_PUSH
+# define _BT_DIAG_POP
+# define _BT_DIAG_IGNORE
+#endif
+
 #define _bt_is_signed_type(type)	((type) -1 < (type) 0)
 
 /*
@@ -345,6 +365,7 @@ do {									\
 	unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */	\
 	unsigned long start_unit, end_unit, this_unit;			\
 	unsigned long end, cshift; /* cshift is "complement shift" */	\
+	bool is_signed_type;						\
 									\
 	if (!__length) {						\
 		*__vptr = 0;						\
@@ -356,7 +377,11 @@ do {									\
 	end_unit = (end + (ts - 1)) / ts;				\
 									\
 	this_unit = end_unit - 1;					\
-	if (_bt_is_signed_type(__typeof__(__v))				\
+	_BT_DIAG_PUSH							\
+	_BT_DIAG_IGNORE_TYPE_LIMITS					\
+	is_signed_type = _bt_is_signed_type(__typeof__(__v));		\
+	_BT_DIAG_POP							\
+	if (is_signed_type						\
 	    && (__ptr[this_unit] & _bt_lshift((type) 1, (end % ts ? end % ts : ts) - 1))) \
 		__v = ~(__typeof__(__v)) 0;				\
 	else								\
@@ -412,6 +437,7 @@ do {									\
 	unsigned long ts = sizeof(type) * CHAR_BIT; /* type size */	\
 	unsigned long start_unit, end_unit, this_unit;			\
 	unsigned long end, cshift; /* cshift is "complement shift" */	\
+	bool is_signed_type;						\
 									\
 	if (!__length) {						\
 		*__vptr = 0;						\
@@ -423,7 +449,11 @@ do {									\
 	end_unit = (end + (ts - 1)) / ts;				\
 									\
 	this_unit = start_unit;						\
-	if (_bt_is_signed_type(__typeof__(__v))				\
+	_BT_DIAG_PUSH							\
+	_BT_DIAG_IGNORE_TYPE_LIMITS					\
+	is_signed_type = _bt_is_signed_type(__typeof__(__v));		\
+	_BT_DIAG_POP							\
+	if (is_signed_type						\
 	    && (__ptr[this_unit] & _bt_lshift((type) 1, ts - (__start % ts) - 1))) \
 		__v = ~(__typeof__(__v)) 0;				\
 	else								\