On Fri, Feb 23, 2024 at 11:03:36AM -0800, Tyler Retzlaff wrote:
> The current location used for __rte_aligned(a) for alignment of types
> and variables is not compatible with MSVC. There is only a single
> location accepted by both toolchains.
>
> For variables standard C11 offers alignas(a) supported by conformant
> compilers i.e. both MSVC and GCC.
>
> For types the standard offers no alignment facility that compatibly
> interoperates with C and C++ but may be achieved by relocating the
> placement of __rte_aligned(a) to the aforementioned location accepted
> by all currently supported toolchains.
>
> To allow alignment for both compilers do the following:
>
> * Expand __rte_aligned(a) to __declspec(align(a)) when building
> with MSVC.
>
> * Move __rte_aligned from the end of {struct,union} definitions to
> be between {struct,union} and tag.
>
> The placement between {struct,union} and the tag allows the desired
> alignment to be imparted on the type regardless of the toolchain being
> used for all of GCC, LLVM, MSVC compilers building both C and C++.
>
> * Replace use of __rte_aligned(a) on variables/fields with alignas(a).
>
> Signed-off-by: Tyler Retzlaff <roret...@linux.microsoft.com>
> Acked-by: Morten Brørup <m...@smartsharesystems.com>
> ---
> lib/eal/arm/include/rte_vect.h | 4 ++--
> lib/eal/common/malloc_elem.h | 4 ++--
> lib/eal/common/malloc_heap.h | 4 ++--
> lib/eal/common/rte_keepalive.c | 3 ++-
> lib/eal/common/rte_random.c | 4 ++--
> lib/eal/common/rte_service.c | 8 ++++----
> lib/eal/include/generic/rte_atomic.h | 4 ++--
> lib/eal/include/rte_common.h | 23 +++++++++++++++--------
> lib/eal/loongarch/include/rte_vect.h | 8 ++++----
> lib/eal/ppc/include/rte_vect.h | 4 ++--
> lib/eal/riscv/include/rte_vect.h | 4 ++--
> lib/eal/x86/include/rte_vect.h | 4 ++--
> lib/eal/x86/rte_power_intrinsics.c | 10 ++++++----
> 13 files changed, 47 insertions(+), 37 deletions(-)
>
Just to chime in with one additional benefit of this change - it will
prevent static analysers, IDEs and doxygen[1] from ever mistaking the
__rte_aligned tag at the end of a struct define as being a variable
definition. In the absence of a macro definition from our DPDK header files
this defines a variable called __rte_cache_aligned (as in [1]!):
struct xyz {
} __rte_cache_aligned;
while this just gives an error to let you know the definiton is missing:
struct __rte_cache_aligned xyz {
};
Acked-by: Bruce Richardson <bruce.richard...@intel.com>
[1]
http://doc.dpdk.org/api/structrte__ring.html#a43d0b019eced25dc6c357f3b4f0f47e5
