Structured kernel parameter (with array) gets wrong result with dx backend about luisacompute HOT 6 CLOSED

Hi, @swfly

Thanks for reporting this. I tried to fix the alignment issue with vector3 arrays in the DX backend in 38abe63, which should now pass the test code you provided.

For other alignment issues with structures,

Actually I think it's not only a problem of using array in this structure. In my actual code I have a camera struct to pass to kernels and it apparently has alignment problem even without arrays.

Would you please provide the struct that causes the problem? Thanks!

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Hi @Mike-Leo-Smith, great work yes it solves the problem!
For another case I just tested and still buggy... In the following code I just use the a similar struct with an extra bool variable instead, and it breaks the alignment immediately. When I saw the generated hlsl with ":8" I can feel the risk there (maybe I was wrong tho)!

#include <luisa-compute.h>
#include <dsl/sugar.h>

using namespace luisa;
using namespace luisa::compute;

struct foo
{
    bool bar = false;
    luisa::float3 test1 = { 0,0,0 };
};
LUISA_STRUCT(foo, bar, test1) {};

int main(int args, char* argv[])
{
    std::vector<std::array<uint8_t, 4u>> download_image(1280 * 720);
    {
        Context context{ argv[0] };
        auto device = context.create_device("dx");
        auto stream = device.create_stream();
        auto device_image = device.create_image<float>(PixelStorage::BYTE4, 1280, 720, 0u);

        Kernel2D fill_image_kernel = [&](Var<foo> bar) noexcept
        {
            Var coord = dispatch_id().xy();
            device_image.write(coord, make_float4(bar.test1, 1.f));
        };
        auto fill_image = device.compile(fill_image_kernel);

        foo b;
        b.test1 = { 0,1,0 };

        stream
            << fill_image(b).dispatch(1280, 720)
            << device_image.copy_to(download_image.data())
            << synchronize();// Step 5: Synchronize the stream
    }

    Window window{ "Display", uint2{ 1280,720 } };
    window.set_key_callback([&](int key, int action) noexcept
    {
        if (action == GLFW_PRESS && key == GLFW_KEY_ESCAPE)
        {
            window.set_should_close();
        }
    });
    auto frame_count = 0u;
    window.run([&]
    {
        window.set_background(download_image.data(), uint2{ 1280,720 });
    });
}

I think by looking at your mentioned commit I should be able to fix this myself since the problems look similar. But you are a lot more familiar with luisa, so if you happen to have time to fix, it'll be the best.

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so if you happen to have time to fix, it'll be the best.

OK! I'll look into this.

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Hi, @swfly

I think I've fixed the struct padding bug with bool members in 35b8ef6. Would you please verify if it now works with your structures?

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Thanks @Mike-Leo-Smith
Now my camera struct finally works and I don't need to use any workaround anymore. Let's close this issue.

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Great!

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