[PATCH v5 24/39] pdcp: 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/pdcp/rte_pdcp.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/lib/pdcp/rte_pdcp.h b/lib/pdcp/rte_pdcp.h
index dd8b6e4..f74524f 100644
--- a/lib/pdcp/rte_pdcp.h
+++ b/lib/pdcp/rte_pdcp.h
@@ -49,7 +49,7 @@ typedef uint16_t (*rte_pdcp_post_p_t)(const struct rte_pdcp_entity *entity,
  * A PDCP entity is associated either to the control plane or the user plane
  * depending on which radio bearer it is carrying data for.
  */
-struct rte_pdcp_entity {
+struct __rte_cache_aligned rte_pdcp_entity {
 	/** Entity specific pre-process handle. */
 	rte_pdcp_pre_p_t pre_process;
 	/** Entity specific post-process handle. */
@@ -66,7 +66,7 @@ struct rte_pdcp_entity {
 	 * hold additionally 'max_pkt_cache' number of packets.
 	 */
 	uint32_t max_pkt_cache;
-} __rte_cache_aligned;
+};
 
 /**
  * Callback function type for t-Reordering timer start, set during PDCP entity establish.
-- 
1.8.3.1