From 614729daeb0078707fc2514749de5604cb38bfb2 Mon Sep 17 00:00:00 2001 From: Tuncer Ayaz Date: Tue, 10 May 2011 18:53:19 +0200 Subject: 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 TODO: Reconsider use of union once gcc-4.1 is obsolete? --- erts/emulator/test/mtx_SUITE_data/mtx_SUITE.c | 46 ++++++++++-------- erts/emulator/test/nif_SUITE_data/nif_SUITE.c | 38 +++++++++------ erts/example/matrix_nif.c | 70 ++++++++++++++++----------- 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 + * TODO: Reconsider use of union once gcc-4.1 is obsolete?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); -- cgit v1.2.3