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Add explicit-pitch makeMdSpan coverage #20

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69f59fe
Add makeMdSpan(any) coverage
Apr 6, 2026
c82fc13
Add explicit-pitch makeMdSpan coverage
Apr 8, 2026
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134 changes: 134 additions & 0 deletions test/unit/mem/constCorrectness.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -835,6 +835,140 @@ TEST_CASE(
}
}

TEST_CASE(
"alpaka::makeMdSpan(any) preserves host shape alignment and inner constness",
"[mem][mdspan][correctness][makeMdSpan]")
{
auto mutableBuffer = alpaka::onHost::allocHost<int>(alpaka::Vec{2u, 3u});
auto mutableView = mutableBuffer.getView();
auto const& outerConstBuffer = mutableBuffer;
auto const& outerConstView = mutableView;

alignas(32) std::array<int const, 2 * 3> innerConstStorage{0, 1, 2, 3, 4, 5};
auto innerConstView
= alpaka::makeView(alpaka::api::host, innerConstStorage.data(), alpaka::Vec{2u, 3u}, alpaka::Alignment<32>{});

auto mutableBufferMdSpan = alpaka::makeMdSpan(mutableBuffer);
auto mutableViewMdSpan = alpaka::makeMdSpan(mutableView);
auto outerConstBufferMdSpan = alpaka::makeMdSpan(outerConstBuffer);
auto outerConstViewMdSpan = alpaka::makeMdSpan(outerConstView);
auto innerConstViewMdSpan = alpaka::makeMdSpan(innerConstView);

SECTION("compile-time rebuilding keeps host layout metadata and inner constness")
{
// `makeMdSpan(any)` should rebuild host buffers and views without changing shape, pitches, alignment, or the
// pointed-to constness encoded by the source object.
static_assert(std::same_as<
std::remove_cvref_t<decltype(mutableBufferMdSpan.getExtents())>,
std::remove_cvref_t<decltype(mutableBuffer.getExtents())>>);
static_assert(std::same_as<
std::remove_cvref_t<decltype(mutableBufferMdSpan.getPitches())>,
std::remove_cvref_t<decltype(mutableBuffer.getPitches())>>);
static_assert(
std::same_as<decltype(mutableBufferMdSpan.getAlignment()), decltype(mutableBuffer.getAlignment())>);
static_assert(!std::is_const_v<std::remove_pointer_t<decltype(mutableBufferMdSpan.data())>>);
static_assert(!std::is_const_v<std::remove_reference_t<decltype(mutableBufferMdSpan[alpaka::Vec{0u, 0u}])>>);

static_assert(std::same_as<
std::remove_cvref_t<decltype(mutableViewMdSpan.getExtents())>,
std::remove_cvref_t<decltype(mutableView.getExtents())>>);
static_assert(std::same_as<
std::remove_cvref_t<decltype(mutableViewMdSpan.getPitches())>,
std::remove_cvref_t<decltype(mutableView.getPitches())>>);
static_assert(std::same_as<decltype(mutableViewMdSpan.getAlignment()), decltype(mutableView.getAlignment())>);
static_assert(!std::is_const_v<std::remove_pointer_t<decltype(mutableViewMdSpan.data())>>);
static_assert(!std::is_const_v<std::remove_reference_t<decltype(mutableViewMdSpan[alpaka::Vec{0u, 0u}])>>);

static_assert(std::same_as<
std::remove_cvref_t<decltype(outerConstBufferMdSpan.getExtents())>,
std::remove_cvref_t<decltype(outerConstBuffer.getExtents())>>);
static_assert(std::same_as<
std::remove_cvref_t<decltype(outerConstBufferMdSpan.getPitches())>,
std::remove_cvref_t<decltype(outerConstBuffer.getPitches())>>);
static_assert(
std::same_as<decltype(outerConstBufferMdSpan.getAlignment()), decltype(outerConstBuffer.getAlignment())>);
static_assert(std::is_const_v<std::remove_pointer_t<decltype(outerConstBufferMdSpan.data())>>);
static_assert(std::is_const_v<std::remove_reference_t<decltype(outerConstBufferMdSpan[alpaka::Vec{0u, 0u}])>>);

static_assert(std::same_as<
std::remove_cvref_t<decltype(outerConstViewMdSpan.getExtents())>,
std::remove_cvref_t<decltype(outerConstView.getExtents())>>);
static_assert(std::same_as<
std::remove_cvref_t<decltype(outerConstViewMdSpan.getPitches())>,
std::remove_cvref_t<decltype(outerConstView.getPitches())>>);
static_assert(
std::same_as<decltype(outerConstViewMdSpan.getAlignment()), decltype(outerConstView.getAlignment())>);
static_assert(std::is_const_v<std::remove_pointer_t<decltype(outerConstViewMdSpan.data())>>);
static_assert(std::is_const_v<std::remove_reference_t<decltype(outerConstViewMdSpan[alpaka::Vec{0u, 0u}])>>);

static_assert(std::same_as<
std::remove_cvref_t<decltype(innerConstViewMdSpan.getExtents())>,
std::remove_cvref_t<decltype(innerConstView.getExtents())>>);
static_assert(std::same_as<
std::remove_cvref_t<decltype(innerConstViewMdSpan.getPitches())>,
std::remove_cvref_t<decltype(innerConstView.getPitches())>>);
static_assert(
std::same_as<decltype(innerConstViewMdSpan.getAlignment()), decltype(innerConstView.getAlignment())>);
static_assert(std::is_const_v<std::remove_pointer_t<decltype(innerConstViewMdSpan.data())>>);
static_assert(std::is_const_v<std::remove_reference_t<decltype(innerConstViewMdSpan[alpaka::Vec{0u, 0u}])>>);
}
}

TEST_CASE(
"alpaka::makeMdSpan(pointer, extents, pitches, alignment) preserves explicit host metadata and inner constness",
"[mem][mdspan][correctness][makeMdSpan]")
{
auto const extents = alpaka::Vec{2u, 3u, 4u};
auto const explicitPitches = alpaka::Vec{80u, 20u, 4u};
alignas(64) std::array<int, 2 * 3 * 5 * 2> mutableStorage{};
alignas(64) std::array<int const, 2 * 3 * 5 * 2> innerConstStorage{};

auto mutableExplicitPitchMdSpan
= alpaka::makeMdSpan(mutableStorage.data(), extents, explicitPitches, alpaka::Alignment<64>{});
auto const outerConstExplicitPitchMdSpan
= alpaka::makeMdSpan(mutableStorage.data(), extents, explicitPitches, alpaka::Alignment<64>{});
auto innerConstExplicitPitchMdSpan
= alpaka::makeMdSpan(innerConstStorage.data(), extents, explicitPitches, alpaka::Alignment<64>{});

SECTION("compile-time explicit pitches stay part of the rebuilt mdspan contract")
{
// The raw explicit-pitch overload should keep the caller-supplied host layout, alignment, and pointed-to
// constness instead of normalizing the span back to a packed representation.
static_assert(std::same_as<
std::remove_cvref_t<decltype(mutableExplicitPitchMdSpan.getExtents())>,
std::remove_cvref_t<decltype(extents)>>);
static_assert(std::same_as<
std::remove_cvref_t<decltype(mutableExplicitPitchMdSpan.getPitches())>,
std::remove_cvref_t<decltype(explicitPitches)>>);
static_assert(std::same_as<decltype(mutableExplicitPitchMdSpan.getAlignment()), alpaka::Alignment<64>>);
static_assert(!std::is_const_v<std::remove_pointer_t<decltype(mutableExplicitPitchMdSpan.data())>>);
static_assert(
!std::is_const_v<std::remove_reference_t<decltype(mutableExplicitPitchMdSpan[alpaka::Vec{0u, 0u, 0u}])>>);

static_assert(std::same_as<
std::remove_cvref_t<decltype(outerConstExplicitPitchMdSpan.getExtents())>,
std::remove_cvref_t<decltype(extents)>>);
static_assert(std::same_as<
std::remove_cvref_t<decltype(outerConstExplicitPitchMdSpan.getPitches())>,
std::remove_cvref_t<decltype(explicitPitches)>>);
static_assert(std::same_as<decltype(outerConstExplicitPitchMdSpan.getAlignment()), alpaka::Alignment<64>>);
static_assert(std::is_const_v<std::remove_pointer_t<decltype(outerConstExplicitPitchMdSpan.data())>>);
static_assert(std::is_const_v<
std::remove_reference_t<decltype(outerConstExplicitPitchMdSpan[alpaka::Vec{0u, 0u, 0u}])>>);

static_assert(std::same_as<
std::remove_cvref_t<decltype(innerConstExplicitPitchMdSpan.getExtents())>,
std::remove_cvref_t<decltype(extents)>>);
static_assert(std::same_as<
std::remove_cvref_t<decltype(innerConstExplicitPitchMdSpan.getPitches())>,
std::remove_cvref_t<decltype(explicitPitches)>>);
static_assert(std::same_as<decltype(innerConstExplicitPitchMdSpan.getAlignment()), alpaka::Alignment<64>>);
static_assert(std::is_const_v<std::remove_pointer_t<decltype(innerConstExplicitPitchMdSpan.data())>>);
static_assert(std::is_const_v<
std::remove_reference_t<decltype(innerConstExplicitPitchMdSpan[alpaka::Vec{0u, 0u, 0u}])>>);
}
}

TEST_CASE("View::getMdSpan keeps host mutability boundaries", "[mem][view][mdspan][correctness]")
{
alignas(32) std::array<int, 2 * 3> storage{};
Expand Down
96 changes: 96 additions & 0 deletions test/unit/mem/mdIterator.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -175,6 +175,102 @@ TEST_CASE("mdIterator host coverage", "[mem][mdIterator][iterator]")
REQUIRE(&mdSpan[sampleIdx] == &packedView[sampleIdx]);
}

SECTION("makeMdSpan(any) rebuilds host buffers and views without breaking aliasing")
{
// Rebuilding an MdSpan from an existing host buffer or view should preserve the layout contract and keep
// direct access bound to the original storage.
auto const extents = alpaka::Vec{2u, 3u, 4u};
auto buffer = onHost::allocHost<int>(extents);
auto bufferMdSpan = alpaka::makeMdSpan(buffer);

meta::ndLoopIncIdx(
extents,
[&](alpaka::concepts::Vector<uint32_t, 3> auto idx)
{ buffer[idx] = static_cast<int>(100u + linearize(extents, idx)); });

alignas(64) std::array<int, 2 * 3 * 4> storage{};
for(std::size_t i = 0; i < storage.size(); ++i)
storage[i] = static_cast<int>(i);

auto view = alpaka::makeView(api::host, storage.data(), extents, alpaka::Alignment<64>{});
auto mdSpan = alpaka::makeMdSpan(view);
auto const constMdSpan = alpaka::makeMdSpan(std::as_const(view));

REQUIRE(bufferMdSpan.getExtents() == buffer.getExtents());
REQUIRE(bufferMdSpan.getPitches() == buffer.getPitches());
REQUIRE(bufferMdSpan.data() == buffer.data());
STATIC_REQUIRE(std::is_same_v<decltype(bufferMdSpan.getAlignment()), decltype(buffer.getAlignment())>);

REQUIRE(mdSpan.getExtents() == view.getExtents());
REQUIRE(mdSpan.getPitches() == view.getPitches());
REQUIRE(mdSpan.data() == view.data());
STATIC_REQUIRE(std::is_same_v<decltype(mdSpan.getAlignment()), alpaka::Alignment<64>>);
STATIC_REQUIRE(std::is_same_v<decltype(constMdSpan.getAlignment()), alpaka::Alignment<64>>);
static_assert(!std::is_const_v<std::remove_reference_t<decltype(mdSpan[alpaka::Vec{0u, 0u, 0u}])>>);
static_assert(std::is_const_v<std::remove_reference_t<decltype(constMdSpan[alpaka::Vec{0u, 0u, 0u}])>>);

auto const sampleIdx = alpaka::Vec{1u, 2u, 3u};
mdSpan[sampleIdx] = 777;
REQUIRE(view[sampleIdx] == 777);
REQUIRE(storage[storage.size() - 1u] == 777);
REQUIRE(&mdSpan[sampleIdx] == &view[sampleIdx]);
REQUIRE(&constMdSpan[sampleIdx] == &view[sampleIdx]);

auto const visited = collectValues(mdSpan);
REQUIRE(visited.size() == storage.size());
REQUIRE(visited.front() == 0);
REQUIRE(visited.back() == 777);
REQUIRE(collectValues(constMdSpan) == visited);
}

SECTION("explicit-pitch makeMdSpan keeps padded host layout and aliases the same storage")
{
// The raw explicit-pitch overload must keep caller-provided padded pitches for indexing instead of deriving a
// packed layout from the extents.
auto const extents = alpaka::Vec{2u, 3u, 4u};
auto const explicitPitches = alpaka::Vec{80u, 20u, 4u};
auto const packedPitches = alpaka::calculatePitchesFromExtents<int>(extents);
alignas(64) std::array<int, 40> mutableStorage{};
mutableStorage.fill(-1);
alignas(64) std::array<int const, 40> innerConstStorage{};

auto mdSpan = alpaka::makeMdSpan(mutableStorage.data(), extents, explicitPitches, alpaka::Alignment<64>{});
auto const outerConstMdSpan
= alpaka::makeMdSpan(mutableStorage.data(), extents, explicitPitches, alpaka::Alignment<64>{});
auto innerConstMdSpan
= alpaka::makeMdSpan(innerConstStorage.data(), extents, explicitPitches, alpaka::Alignment<64>{});

REQUIRE(mdSpan.getExtents() == extents);
REQUIRE(mdSpan.getPitches() == explicitPitches);
REQUIRE(mdSpan.getPitches() != packedPitches);
REQUIRE(mdSpan.data() == mutableStorage.data());
STATIC_REQUIRE(std::is_same_v<decltype(mdSpan.getAlignment()), alpaka::Alignment<64>>);
STATIC_REQUIRE(std::is_same_v<decltype(outerConstMdSpan.getAlignment()), alpaka::Alignment<64>>);
STATIC_REQUIRE(std::is_same_v<decltype(innerConstMdSpan.getAlignment()), alpaka::Alignment<64>>);
static_assert(!std::is_const_v<std::remove_reference_t<decltype(mdSpan[alpaka::Vec{0u, 0u, 0u}])>>);
static_assert(std::is_const_v<std::remove_reference_t<decltype(outerConstMdSpan[alpaka::Vec{0u, 0u, 0u}])>>);
static_assert(std::is_const_v<std::remove_reference_t<decltype(innerConstMdSpan[alpaka::Vec{0u, 0u, 0u}])>>);

mutableStorage[5] = -50;
mutableStorage[4] = -40;
REQUIRE(mdSpan[alpaka::Vec{0u, 1u, 0u}] == -50);

mutableStorage[20] = 220;
mutableStorage[12] = 120;
REQUIRE(mdSpan[alpaka::Vec{1u, 0u, 0u}] == 220);

auto const sampleIdx = alpaka::Vec{1u, 2u, 3u};
mdSpan[sampleIdx] = 1323;
REQUIRE(mutableStorage[33] == 1323);
REQUIRE(mutableStorage[23] == -1);
REQUIRE(&mdSpan[sampleIdx] == &mutableStorage[33]);
REQUIRE(&outerConstMdSpan[sampleIdx] == &mutableStorage[33]);

auto iter = mdSpan.begin();
++iter;
REQUIRE(&*iter == &mutableStorage[1]);
}

SECTION("pre-increment and post-increment advance one element at a time")
{
// Forward-iterator increments need to preserve the old value for post-increment and return self for
Expand Down