[PATCH v6 23/39] port: use C11 alignas

[Tyler Retzlaff]

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:

* 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 <roretzla at linux.microsoft.com>
Acked-by: Morten Brørup <mb at smartsharesystems.com>
---
 lib/port/rte_port_frag.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/port/rte_port_frag.c b/lib/port/rte_port_frag.c
index 883601a..0940f94 100644
--- a/lib/port/rte_port_frag.c
+++ b/lib/port/rte_port_frag.c
@@ -34,7 +34,7 @@
 			struct rte_mempool *pool_direct,
 			struct rte_mempool *pool_indirect);
 
-struct rte_port_ring_reader_frag {
+struct __rte_cache_aligned rte_port_ring_reader_frag {
 	struct rte_port_in_stats stats;
 
 	/* Input parameters */
@@ -53,7 +53,7 @@ struct rte_port_ring_reader_frag {
 	uint32_t pos_frags;
 
 	frag_op f_frag;
-} __rte_cache_aligned;
+};
 
 static void *
 rte_port_ring_reader_frag_create(void *params, int socket_id, int is_ipv4)
-- 
1.8.3.1