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authorTuncer Ayaz <[email protected]>2011-05-10 18:53:19 +0200
committerTuncer Ayaz <[email protected]>2011-08-15 18:52:20 +0200
commit614729daeb0078707fc2514749de5604cb38bfb2 (patch)
treef772a9a685291b696dce84cc85f74297c0a567ce /erts
parent4c3ab3467750003221f95d820e16f04cd861c308 (diff)
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erts: use a union to avoid strict aliasing issues
Use a union for pointer type conversion to avoid compiler warnings about strict-aliasing violations with gcc-4.1. gcc >= 4.2 does not emit the warning. TODO: Reconsider use of union once gcc-4.1 is obsolete?
Diffstat (limited to 'erts')
-rw-r--r--erts/emulator/test/mtx_SUITE_data/mtx_SUITE.c46
-rw-r--r--erts/emulator/test/nif_SUITE_data/nif_SUITE.c38
-rw-r--r--erts/example/matrix_nif.c70
3 files changed, 91 insertions, 63 deletions
diff --git a/erts/emulator/test/mtx_SUITE_data/mtx_SUITE.c b/erts/emulator/test/mtx_SUITE_data/mtx_SUITE.c
index 818023211c..0e4065c26b 100644
--- a/erts/emulator/test/mtx_SUITE_data/mtx_SUITE.c
+++ b/erts/emulator/test/mtx_SUITE_data/mtx_SUITE.c
@@ -552,13 +552,19 @@ create_rwlock(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
static ERL_NIF_TERM
rwlock_op(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
{
- rwlock_resource_t *rwlr;
+ /*
+ * Use a union for pointer type conversion to avoid compiler warnings
+ * about strict-aliasing violations with gcc-4.1. gcc >= 4.2 does not
+ * emit the warning.
+ * TODO: Reconsider use of union once gcc-4.1 is obsolete?
+ */
+ union { void* vp; rwlock_resource_t *p; } rwlr;
int blocking, write, wait_locked, wait_unlocked;
if (argc != 5)
goto badarg;
- if (!enif_get_resource(env, argv[0], enif_priv_data(env), (void **) &rwlr))
+ if (!enif_get_resource(env, argv[0], enif_priv_data(env), &rwlr.vp))
goto badarg;
blocking = get_bool(env, argv[1]);
@@ -581,22 +587,22 @@ rwlock_op(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
if (write) {
if (blocking)
- RWMUTEX_WLOCK(rwlr->rwlock);
+ RWMUTEX_WLOCK(rwlr.p->rwlock);
else
- while (EBUSY == RWMUTEX_TRYWLOCK(rwlr->rwlock));
- if (rwlr->lock_check) {
- ASSERT(!ATOMIC_READ(&rwlr->is_locked));
- ATOMIC_SET(&rwlr->is_locked, -1);
+ while (EBUSY == RWMUTEX_TRYWLOCK(rwlr.p->rwlock));
+ if (rwlr.p->lock_check) {
+ ASSERT(!ATOMIC_READ(&rwlr.p->is_locked));
+ ATOMIC_SET(&rwlr.p->is_locked, -1);
}
}
else {
if (blocking)
- RWMUTEX_RLOCK(rwlr->rwlock);
+ RWMUTEX_RLOCK(rwlr.p->rwlock);
else
- while (EBUSY == RWMUTEX_TRYRLOCK(rwlr->rwlock));
- if (rwlr->lock_check) {
- ASSERT(ATOMIC_READ(&rwlr->is_locked) >= 0);
- ATOMIC_INC(&rwlr->is_locked);
+ while (EBUSY == RWMUTEX_TRYRLOCK(rwlr.p->rwlock));
+ if (rwlr.p->lock_check) {
+ ASSERT(ATOMIC_READ(&rwlr.p->is_locked) >= 0);
+ ATOMIC_INC(&rwlr.p->is_locked);
}
}
@@ -604,18 +610,18 @@ rwlock_op(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
milli_sleep(wait_locked);
if (write) {
- if (rwlr->lock_check) {
- ASSERT(ATOMIC_READ(&rwlr->is_locked) == -1);
- ATOMIC_SET(&rwlr->is_locked, 0);
+ if (rwlr.p->lock_check) {
+ ASSERT(ATOMIC_READ(&rwlr.p->is_locked) == -1);
+ ATOMIC_SET(&rwlr.p->is_locked, 0);
}
- RWMUTEX_WUNLOCK(rwlr->rwlock);
+ RWMUTEX_WUNLOCK(rwlr.p->rwlock);
}
else {
- if (rwlr->lock_check) {
- ASSERT(ATOMIC_READ(&rwlr->is_locked) > 0);
- ATOMIC_DEC(&rwlr->is_locked);
+ if (rwlr.p->lock_check) {
+ ASSERT(ATOMIC_READ(&rwlr.p->is_locked) > 0);
+ ATOMIC_DEC(&rwlr.p->is_locked);
}
- RWMUTEX_RUNLOCK(rwlr->rwlock);
+ RWMUTEX_RUNLOCK(rwlr.p->rwlock);
}
if (wait_unlocked)
diff --git a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
index 00a1365bc3..92f1bab8dd 100644
--- a/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
+++ b/erts/emulator/test/nif_SUITE_data/nif_SUITE.c
@@ -41,7 +41,18 @@ typedef struct
CallInfo* call_history;
NifModPrivData* nif_mod;
union { ErlNifResourceType* t; long l; } rt_arr[2];
-}PrivData;
+} PrivData;
+
+/*
+ * Use a union for pointer type conversion to avoid compiler warnings
+ * about strict-aliasing violations with gcc-4.1. gcc >= 4.2 does not
+ * emit the warning.
+ * TODO: Reconsider use of union once gcc-4.1 is obsolete?
+ */
+typedef union {
+ void* vp;
+ struct make_term_info* p;
+} mti_t;
void add_call(ErlNifEnv* env, PrivData* data, const char* func_name)
{
@@ -707,7 +718,7 @@ static ERL_NIF_TERM get_resource_type(ErlNifEnv* env, int argc, const ERL_NIF_TE
static ERL_NIF_TERM alloc_resource(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
ErlNifBinary data_bin;
- union { ErlNifResourceType* t; long l;} type;
+ union { ErlNifResourceType* t; long l; } type;
union { void* p; long l;} data;
if (!enif_get_long(env, argv[0], &type.l)
|| !enif_inspect_binary(env, argv[1], &data_bin)
@@ -731,7 +742,7 @@ static ERL_NIF_TERM make_resource(ErlNifEnv* env, int argc, const ERL_NIF_TERM a
static ERL_NIF_TERM make_new_resource(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
ErlNifBinary data_bin;
- union { ErlNifResourceType* t; long l;} type;
+ union { ErlNifResourceType* t; long l; } type;
void* data;
ERL_NIF_TERM ret;
if (!enif_get_long(env, argv[0], &type.l)
@@ -749,7 +760,7 @@ static ERL_NIF_TERM make_new_resource(ErlNifEnv* env, int argc, const ERL_NIF_TE
static ERL_NIF_TERM make_new_resource_binary(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
ErlNifBinary data_bin;
- union { struct binary_resource* p; void* vp; long l;} br;
+ union { struct binary_resource* p; void* vp; long l; } br;
void* buf;
ERL_NIF_TERM ret;
if (!enif_inspect_binary(env, argv[0], &data_bin)
@@ -1269,10 +1280,7 @@ static void msgenv_dtor(ErlNifEnv* env, void* obj)
static ERL_NIF_TERM clear_msgenv(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
- union {
- void* vp;
- struct make_term_info* p;
- }mti;
+ mti_t mti;
if (!enif_get_resource(env, argv[0], msgenv_resource_type, &mti.vp)) {
return enif_make_badarg(env);
}
@@ -1285,7 +1293,7 @@ static ERL_NIF_TERM clear_msgenv(ErlNifEnv* env, int argc, const ERL_NIF_TERM ar
static ERL_NIF_TERM grow_blob(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
- union { void* vp; struct make_term_info* p; }mti;
+ mti_t mti;
ERL_NIF_TERM term;
if (!enif_get_resource(env, argv[0], msgenv_resource_type, &mti.vp)
|| (argc>2 && !enif_get_uint(env,argv[2], &mti.p->n))) {
@@ -1301,7 +1309,7 @@ static ERL_NIF_TERM grow_blob(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[
static ERL_NIF_TERM send_blob(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
- union { void* vp; struct make_term_info* p; }mti;
+ mti_t mti;
ErlNifPid to;
ERL_NIF_TERM copy;
int res;
@@ -1316,7 +1324,7 @@ static ERL_NIF_TERM send_blob(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[
static ERL_NIF_TERM send3_blob(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
- union { void* vp; struct make_term_info* p; }mti;
+ mti_t mti;
ErlNifPid to;
ERL_NIF_TERM copy;
int res;
@@ -1334,7 +1342,7 @@ static ERL_NIF_TERM send3_blob(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv
void* threaded_sender(void *arg)
{
- union { void* vp; struct make_term_info* p; }mti;
+ mti_t mti;
mti.vp = arg;
enif_mutex_lock(mti.p->mtx);
@@ -1349,7 +1357,7 @@ void* threaded_sender(void *arg)
static ERL_NIF_TERM send_blob_thread(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
- union { void* vp; struct make_term_info* p; }mti;
+ mti_t mti;
ERL_NIF_TERM copy;
if (!enif_get_resource(env, argv[0], msgenv_resource_type, &mti.vp)
|| !enif_get_local_pid(env,argv[1], &mti.p->to_pid)) {
@@ -1375,7 +1383,7 @@ static ERL_NIF_TERM send_blob_thread(ErlNifEnv* env, int argc, const ERL_NIF_TER
static ERL_NIF_TERM join_send_thread(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
- union { void* vp; struct make_term_info* p; }mti;
+ mti_t mti;
int err;
if (!enif_get_resource(env, argv[0], msgenv_resource_type, &mti.vp)) {
return enif_make_badarg(env);
@@ -1392,7 +1400,7 @@ static ERL_NIF_TERM join_send_thread(ErlNifEnv* env, int argc, const ERL_NIF_TER
static ERL_NIF_TERM copy_blob(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
- union { void* vp; struct make_term_info* p; }mti;
+ mti_t mti;
if (!enif_get_resource(env, argv[0], msgenv_resource_type, &mti.vp)) {
return enif_make_badarg(env);
}
diff --git a/erts/example/matrix_nif.c b/erts/example/matrix_nif.c
index 0e8ffdebcb..43f9526ae3 100644
--- a/erts/example/matrix_nif.c
+++ b/erts/example/matrix_nif.c
@@ -31,7 +31,19 @@ typedef struct
unsigned nrows;
unsigned ncols;
double* data;
-}Matrix;
+} Matrix;
+
+/*
+ * Use a union for pointer type conversion to avoid compiler warnings
+ * about strict-aliasing violations with gcc-4.1. gcc >= 4.2 does not
+ * emit the warning.
+ * TODO: Reconsider use of union once gcc-4.1 is obsolete?
+ */
+typedef union
+{
+ void* vp;
+ Matrix* p;
+} mx_t;
#define POS(MX, ROW, COL) ((MX)->data[(ROW)* (MX)->ncols + (COL)])
@@ -105,14 +117,14 @@ badarg:
static ERL_NIF_TERM pos(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
/* pos(Matrix, Row, Column) -> float() */
- Matrix* mx;
+ mx_t mx;
unsigned i, j;
- if (!enif_get_resource(env, argv[0], resource_type, (void**)&mx) ||
- !enif_get_uint(env, argv[1], &i) || (--i >= mx->nrows) ||
- !enif_get_uint(env, argv[2], &j) || (--j >= mx->ncols)) {
+ if (!enif_get_resource(env, argv[0], resource_type, &mx.vp) ||
+ !enif_get_uint(env, argv[1], &i) || (--i >= mx.p->nrows) ||
+ !enif_get_uint(env, argv[2], &j) || (--j >= mx.p->ncols)) {
return enif_make_badarg(env);
}
- return enif_make_double(env, POS(mx, i,j));
+ return enif_make_double(env, POS(mx.p, i,j));
}
static ERL_NIF_TERM add(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
@@ -120,37 +132,38 @@ static ERL_NIF_TERM add(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
/* add(Matrix_A, Matrix_B) -> Matrix_Sum */
unsigned i, j;
ERL_NIF_TERM ret;
- Matrix* mxA = NULL;
- Matrix* mxB = NULL;
- Matrix* mxS = NULL;
+ mx_t mxA, mxB, mxS;
+ mxA.p = NULL;
+ mxB.p = NULL;
+ mxS.p = NULL;
- if (!enif_get_resource(env, argv[0], resource_type, (void**)&mxA) ||
- !enif_get_resource(env, argv[1], resource_type, (void**)&mxB) ||
- mxA->nrows != mxB->nrows ||
- mxB->ncols != mxB->ncols) {
+ if (!enif_get_resource(env, argv[0], resource_type, &mxA.vp) ||
+ !enif_get_resource(env, argv[1], resource_type, &mxB.vp) ||
+ mxA.p->nrows != mxB.p->nrows ||
+ mxB.p->ncols != mxB.p->ncols) {
return enif_make_badarg(env);
}
- mxS = alloc_matrix(env, mxA->nrows, mxA->ncols);
- for (i = 0; i < mxA->nrows; i++) {
- for (j = 0; j < mxA->ncols; j++) {
- POS(mxS, i, j) = POS(mxA, i, j) + POS(mxB, i, j);
+ mxS.p = alloc_matrix(env, mxA.p->nrows, mxA.p->ncols);
+ for (i = 0; i < mxA.p->nrows; i++) {
+ for (j = 0; j < mxA.p->ncols; j++) {
+ POS(mxS.p, i, j) = POS(mxA.p, i, j) + POS(mxB.p, i, j);
}
}
- ret = enif_make_resource(env, mxS);
- enif_release_resource(mxS);
+ ret = enif_make_resource(env, mxS.p);
+ enif_release_resource(mxS.p);
return ret;
}
static ERL_NIF_TERM size_of(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
{
/* size(Matrix) -> {Nrows, Ncols} */
- Matrix* mx;
- if (!enif_get_resource(env, argv[0], resource_type, (void**)&mx)) {
+ mx_t mx;
+ if (!enif_get_resource(env, argv[0], resource_type, &mx.vp)) {
return enif_make_badarg(env);
}
- return enif_make_tuple2(env, enif_make_uint(env, mx->nrows),
- enif_make_uint(env, mx->ncols));
+ return enif_make_tuple2(env, enif_make_uint(env, mx.p->nrows),
+ enif_make_uint(env, mx.p->ncols));
}
static ERL_NIF_TERM to_term(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
@@ -158,16 +171,17 @@ static ERL_NIF_TERM to_term(ErlNifEnv* env, int argc, const ERL_NIF_TERM argv[])
/* to_term(Matrix) -> [[first row], [second row], ...,[last row]] */
unsigned i, j;
ERL_NIF_TERM res;
- Matrix* mx = NULL;
+ mx_t mx;
+ mx.p = NULL;
- if (!enif_get_resource(env, argv[0], resource_type, (void**)&mx)) {
+ if (!enif_get_resource(env, argv[0], resource_type, &mx.vp)) {
return enif_make_badarg(env);
}
res = enif_make_list(env, 0);
- for (i = mx->nrows; i-- > 0; ) {
+ for (i = mx.p->nrows; i-- > 0; ) {
ERL_NIF_TERM row = enif_make_list(env, 0);
- for (j = mx->ncols; j-- > 0; ) {
- row = enif_make_list_cell(env, enif_make_double(env, POS(mx,i,j)),
+ for (j = mx.p->ncols; j-- > 0; ) {
+ row = enif_make_list_cell(env, enif_make_double(env, POS(mx.p,i,j)),
row);
}
res = enif_make_list_cell(env, row, res);