Force static flatbuffer memory to be aligned
For buffers which required lots of alignment, we were allocating more
space than needed, and manually aligning inside that space. That
doesn't have a good enough contract to ensure that if the flatbuffer is
loaded back into RAM, it would still be aligned well enough for the
requirements.
Instead, we need to push the alignment requirement out to the allocator,
and then make sure we stay aligned inside the buffer. The std::vector<>
allocator isn't guarenteed to be aligned, so switch everything over to
the AlignedVectorAllocator instead which is aligned.
Change-Id: Ice2aa1316914472f2a3d55f470a4dc957e2caa3c
Signed-off-by: James Kuszmaul <james.kuszmaul@bluerivertech.com>
diff --git a/aos/flatbuffers/static_flatbuffers_test.cc b/aos/flatbuffers/static_flatbuffers_test.cc
index 66938f1..0929d17 100644
--- a/aos/flatbuffers/static_flatbuffers_test.cc
+++ b/aos/flatbuffers/static_flatbuffers_test.cc
@@ -108,7 +108,7 @@
// Test that compiles the same code that is used by an example in
// //aos/documentation/aos/docs/flatbuffers.md.
TEST_F(StaticFlatbuffersTest, DocumentationExample) {
- aos::fbs::VectorAllocator allocator;
+ aos::fbs::AlignedVectorAllocator allocator;
Builder<TestTableStatic> builder(&allocator);
TestTableStatic *object = builder.get();
object->set_scalar(123);
@@ -176,7 +176,7 @@
aos::FlatbufferDetachedBuffer<TestTable> fbb_finished = fbb.Release();
// Using the static flatbuffer API.
- aos::fbs::VectorAllocator allocator;
+ aos::fbs::AlignedVectorAllocator allocator;
Builder<TestTableStatic> static_builder(&allocator);
PopulateStatic(CHECK_NOTNULL(static_builder.get()->add_subtable()));
@@ -218,7 +218,7 @@
// it stays valid at all points.
TEST_F(StaticFlatbuffersTest, ManuallyConstructFlatbuffer) {
{
- aos::fbs::VectorAllocator allocator;
+ aos::fbs::AlignedVectorAllocator allocator;
Builder<SubTableStatic> builder(&allocator);
SubTableStatic *object = builder.get();
if (!builder.AsFlatbufferSpan().Verify()) {
@@ -241,9 +241,7 @@
TestMemory(builder.buffer());
}
{
- // aos::FixedAllocator
- // allocator(TestTableStatic::kUnalignedBufferSize);
- aos::fbs::VectorAllocator allocator;
+ aos::fbs::AlignedVectorAllocator allocator;
Builder<TestTableStatic> builder(&allocator);
TestTableStatic *object = builder.get();
const aos::fbs::testing::TestTable &fbs = object->AsFlatbuffer();
@@ -673,7 +671,7 @@
// Tests that field clearing (and subsequent resetting) works properly.
TEST_F(StaticFlatbuffersTest, ClearFields) {
- aos::fbs::VectorAllocator allocator;
+ aos::fbs::AlignedVectorAllocator allocator;
Builder<TestTableStatic> builder(&allocator);
TestTableStatic *object = builder.get();
// For each field, we will confirm the following:
@@ -859,7 +857,7 @@
// Confirm that we can use the SpanAllocator with a span that provides exactly
// the required buffer size.
TEST_F(StaticFlatbuffersTest, ExactSizeSpanAllocator) {
- uint8_t buffer[Builder<TestTableStatic>::kBufferSize];
+ alignas(64) uint8_t buffer[Builder<TestTableStatic>::kBufferSize];
aos::fbs::SpanAllocator allocator({buffer, sizeof(buffer)});
Builder<TestTableStatic> builder(&allocator);
TestTableStatic *object = builder.get();
@@ -922,7 +920,7 @@
// Verify that if we create a span with extra headroom that that lets us
// dynamically alter the size of vectors in the flatbuffers.
TEST_F(StaticFlatbuffersTest, ExtraLargeSpanAllocator) {
- uint8_t buffer[Builder<TestTableStatic>::kBufferSize + 10000];
+ alignas(64) uint8_t buffer[Builder<TestTableStatic>::kBufferSize + 200 * 64];
aos::fbs::SpanAllocator allocator({buffer, sizeof(buffer)});
Builder<TestTableStatic> builder(&allocator);
TestTableStatic *object = builder.get();
@@ -951,7 +949,7 @@
// Tests that the iterators on the Vector type work.
TEST_F(StaticFlatbuffersTest, IteratorTest) {
- Builder<TestTableStatic> builder(std::make_unique<VectorAllocator>());
+ Builder<TestTableStatic> builder(std::make_unique<AlignedVectorAllocator>());
{
auto vector = builder->add_unspecified_length_vector();
ASSERT_TRUE(vector->reserve(9000));
@@ -1019,7 +1017,8 @@
// Confirm that we can use the FixedStackAllocator
TEST_F(StaticFlatbuffersTest, FixedStackAllocator) {
- aos::fbs::FixedStackAllocator<Builder<TestTableStatic>::kBufferSize>
+ aos::fbs::FixedStackAllocator<Builder<TestTableStatic>::kBufferSize,
+ Builder<TestTableStatic>::kAlign>
allocator;
Builder<TestTableStatic> builder(&allocator);
TestTableStatic *object = builder.get();
@@ -1078,7 +1077,7 @@
object_t.vector_of_strings.push_back("971");
object_t.vector_of_structs.push_back({1, 2});
object_t.subtable = std::make_unique<SubTableT>();
- aos::fbs::VectorAllocator allocator;
+ aos::fbs::AlignedVectorAllocator allocator;
Builder<TestTableStatic> builder(&allocator);
ASSERT_TRUE(builder->FromFlatbuffer(object_t));
ASSERT_TRUE(builder.AsFlatbufferSpan().Verify());
@@ -1123,7 +1122,7 @@
// Tests that we can use the move constructor on a Builder.
TEST_F(StaticFlatbuffersTest, BuilderMoveConstructor) {
- uint8_t buffer[Builder<TestTableStatic>::kBufferSize];
+ alignas(64) uint8_t buffer[Builder<TestTableStatic>::kBufferSize];
aos::fbs::SpanAllocator allocator({buffer, sizeof(buffer)});
Builder<TestTableStatic> builder_from(&allocator);
Builder<TestTableStatic> builder(std::move(builder_from));