From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Thu, 16 Aug 2012 19:57:05 +0000 (-0400)
Subject: Fix: 32-bit x86 strict-aliasing warnings
X-Git-Tag: v2.1.0-rc1~12
X-Git-Url: https://git.lttng.org./?a=commitdiff_plain;h=fa0994718a5855f67bc73546558df0ee742e376a;p=lttng-ust.git

Fix: 32-bit x86 strict-aliasing warnings

Compiling on x86-32 shows the following warnings for filter (with gcc
4.3 and 4.4):

././ust_tests_hello.h:28: note: initialized from here
././ust_tests_hello.h:28: error: dereferencing pointer ‘__stack_data.18’ does break strict-aliasing rules

Fix it by using memcpy when copying to the temporary "stack" array used
to send arguments to the filter.

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

diff --git a/include/lttng/ust-tracepoint-event.h b/include/lttng/ust-tracepoint-event.h
index aac32b96..398f3efa 100644
--- a/include/lttng/ust-tracepoint-event.h
+++ b/include/lttng/ust-tracepoint-event.h
@@ -275,36 +275,50 @@ size_t __event_get_size__##_provider##___##_name(size_t *__dynamic_len, _TP_ARGS
 
 #undef _ctf_integer_ext
 #define _ctf_integer_ext(_type, _item, _src, _byte_order, _base, _written)     \
-	if (lttng_is_signed_type(_type))				       \
-		*(int64_t *) __stack_data = (int64_t) (_type) (_src);	       \
-	else								       \
-		*(uint64_t *) __stack_data = (uint64_t) (_type) (_src);	       \
+	if (lttng_is_signed_type(_type)) {				       \
+		int64_t __ctf_tmp_int64 = (int64_t) (_type) (_src);	       \
+		memcpy(__stack_data, &__ctf_tmp_int64, sizeof(int64_t));       \
+	} else {							       \
+		uint64_t __ctf_tmp_uint64 = (uint64_t) (_type) (_src);	       \
+		memcpy(__stack_data, &__ctf_tmp_uint64, sizeof(uint64_t));     \
+	}								       \
 	__stack_data += sizeof(int64_t);
 
 #undef _ctf_float
 #define _ctf_float(_type, _item, _src, _written)			       \
-	*(double *) __stack_data = (double) (_type) (_src);		       \
-	__stack_data += sizeof(double);
+	{								       \
+		double __ctf_tmp_double = (double) (_type) (_src);	       \
+		memcpy(__stack_data, &__ctf_tmp_double, sizeof(double));       \
+		__stack_data += sizeof(double);				       \
+	}
 
 #undef _ctf_array_encoded
 #define _ctf_array_encoded(_type, _item, _src, _length, _encoding, _written)   \
-	*(unsigned long *) __stack_data = (unsigned long) (_length);	       \
-	__stack_data += sizeof(unsigned long);				       \
-	*(const void **) __stack_data = (_src);				       \
-	__stack_data += sizeof(void *);
+	{								       \
+		unsigned long __ctf_tmp_ulong = (unsigned long) (_length);     \
+		memcpy(__stack_data, &__ctf_tmp_ulong, sizeof(unsigned long)); \
+		__stack_data += sizeof(unsigned long);			       \
+		memcpy(__stack_data, (_src), sizeof(void **));		       \
+		__stack_data += sizeof(void **);			       \
+	}
 
 #undef _ctf_sequence_encoded
 #define _ctf_sequence_encoded(_type, _item, _src, _length_type,		       \
 			_src_length, _encoding, _written)		       \
-	*(unsigned long *) __stack_data = (unsigned long) (_src_length);       \
-	__stack_data += sizeof(unsigned long);				       \
-	*(const void **) __stack_data = (_src);				       \
-	__stack_data += sizeof(void *);
+	{								       \
+		unsigned long __ctf_tmp_ulong = (unsigned long) (_src_length); \
+		memcpy(__stack_data, &__ctf_tmp_ulong, sizeof(unsigned long)); \
+		__stack_data += sizeof(unsigned long);			       \
+		memcpy(__stack_data, (_src), sizeof(void **));		       \
+		__stack_data += sizeof(void **);			       \
+	}
 
 #undef _ctf_string
 #define _ctf_string(_item, _src, _written)				       \
-	*(const void **) __stack_data = (_src);				       \
-	__stack_data += sizeof(void *);
+	{								       \
+		memcpy(__stack_data, (_src), sizeof(void **));		       \
+		__stack_data += sizeof(void *);				       \
+	}
 
 #undef TP_ARGS
 #define TP_ARGS(...) __VA_ARGS__