lib: move alignment attribute on types for MSVC

The current location used for __rte_aligned(a) for alignment of types
is not compatible with MSVC. There is only a single location accepted
by both toolchains.

The standard offers no alignment facility that compatibly interoperates
with C and C++ but it 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++.

Note: this move has an additional benefit as Doxygen is not confused
anymore like for the rte_event_vector struct definition.

Signed-off-by: Tyler Retzlaff <[email protected]>
Acked-by: Morten Brørup <[email protected]>
Acked-by: Bruce Richardson <[email protected]>
Acked-by: Konstantin Ananyev <[email protected]>
Acked-by: Chengwen Feng <[email protected]>
Reviewed-by: Maxime Coquelin <[email protected]>
Signed-off-by: David Marchand <[email protected]>

1 files changed, 23 insertions, 0 deletions

diff --git a/devtools/checkpatches.sh b/devtools/checkpatches.sh
index c47ea59501..8f245ebdab 100755
--- a/devtools/checkpatches.sh
+++ b/devtools/checkpatches.sh
@@ -336,6 +336,21 @@ check_internal_tags() { # <patch>
 	return $res
 }
 
+check_aligned_attributes() { # <patch>
+	res=0
+
+	for token in __rte_aligned __rte_cache_aligned __rte_cache_min_aligned; do
+		if [ $(grep -E '^\+.*\<'$token'\>' "$1" | \
+				grep -vE '\<(struct|union)[[:space:]]*'$token'\>' | \
+				wc -l) != 0 ]; then
+			echo "Please use $token only for struct or union types alignment."
+			res=1
+		fi
+	done
+
+	return $res
+}
+
 check_release_notes() { # <patch>
 	rel_notes_prefix=doc/guides/rel_notes/release_
 	IFS=. read year month release < VERSION
@@ -445,6 +460,14 @@ check () { # <patch-file> <commit>
 		ret=1
 	fi
 
+	! $verbose || printf '\nChecking alignment attributes:\n'
+	report=$(check_aligned_attributes "$tmpinput")
+	if [ $? -ne 0 ] ; then
+		$headline_printed || print_headline "$subject"
+		printf '%s\n' "$report"
+		ret=1
+	fi
+
 	! $verbose || printf '\nChecking release notes updates:\n'
 	report=$(check_release_notes "$tmpinput")
 	if [ $? -ne 0 ] ; then