This page is a "brief" summary of some of the huge number of improvements in GCC 17. You may also want to check out our Porting to GCC 17 page and the full GCC documentation.
Note: GCC 17 has not been released yet, so this document is a work-in-progress.
See the GCC OpenACC wiki page for general information.
init, set, and shutdown
directives.See the GNU Offloading and Multi-Processing Project (GOMP) page for general information.
declare
mapper) in C and C++ has been improved. The uses_allocators
clause now accepts traits (also with the OpenMP 5.1 syntax).iterator modifier to the
map, to, and from clauses has been
improved for C and C++ and initial support for Fortran added.device_type clause is now
supported on the target construct.
omp_get_device_distances API
routine has been added that can be used to find the offload devices that
are closest, in terms of NUMA node, to the thread that called the
routine. The multidimensional-information API routines have been added,
albeit GCC currently only supports one spatial dimension; already useful
are the new
omp_get_supported_teams_dim and
omp_get_supported_threads_dim routines that return,
respectively, the maximal number of teams and threads that GCC supports
on a given device.__builtin_call_static_chain and
__builtin_call_code_address can be used to obtain the
static chain and the underlying code address of a nested function.
This allows calling of the nested function indirectly without the use
of a trampoline.
std::format in constexpr functions.std::filesystem support for Windows symlinks,
thanks to Adam Wood.c_f_strpointer intrinsic is now
supported. Additionally, the f_c_string intrinsic
has been reimplemented to be more efficient.
-Wunused-but-set-variables option is now
also effective for Fortran.
-Wundefined-vars, enabled
by -Wall, warns about variables that are used that
have not been defined (i.e. have no value assigned to them).
-Wunused-read and
-Wunused-intent-out, both
enabled by -Wextra,
warn about variables in READ statements and variables passed to
INTENT(OUT) variables, respectively, whose values are never used.
_Accum
types.[[len=spec]]
annotations. The code size is specified in units of 16-bit words and
is set to the sum over all such notes.
The notes can be deactivated with the new command-line option
-mno-asm-len-notes so that the default length applies.
The diagnostic behavior can be adjusted with
-Wasm-len-notes.
_ep[i|u]{32,64} suffix, which denotes packed
elements, to _[i|u]{32,64}, with _si{32,64}
aliases for the signed variants. The old names were never accepted by
other x86 compilers. See the
porting guide
for the list of affected intrinsics.
-m31 was removed and as a consequence
-mesa support.
-mlra is now ineffective but kept around for
backwards compatibility
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These pages are maintained by the GCC team. Last modified 2026-08-15.