Vulkan Validation Error when using multiple dynamic indexing

[lorinjacot]

Description
When trying to run the code

@fragment
fn fs_main() -> @location(0) vec4f {
    let my_array = array(
        vec2f(0.0, 0.0),
        vec2f(0.0, 0.0),
    );

    let val_0 = my_array[index_0];
    let val_1 = my_array[index_0];

    return (val_0 * val_1).xxyy;
}

on the Vulkan backend, a Validation Error is raised:

Validation Error: [ VUID-VkShaderModuleCreateInfo-pCode-08737 ] | MessageID = 0xa5625282 | vkCreateShaderModule(): pCreateInfo->pCode (spirv-val produced an error):
    ID '28[%28]' has not been defined
      OpStore %28 %25
    The Vulkan spec states: If pCode is a pointer to SPIR-V code, pCode must adhere to the validation rules described by the Validation Rules within a Module section of the SPIR-V Environment appendix (https://vulkan.lunarg.com/doc/view/1.4.304.0/windows/1.4-extensions/vkspec.html#VUID-VkShaderModuleCreateInfo-pCode-08737)

The same fragment shader runs fine on DirectX 12 and OpenGL.

Repro steps

git clone https://github.com/lorinjacot/wgsl-indexing-bug.git
cd wgsl-indexing-bug
cargo run

Expected vs observed behavior
I expect the program to run and exit without any error. Currently, the program exits with the error (exit code: 0xc0000005, STATUS_ACCESS_VIOLATION) on the Vulkan backend.

Platform
OS: Windows 11 Home, version 24H2
wgpu version: 24.0.1
GPU: Integrated, AMD Ryzen 5 5500U with Radeon Graphics

[ryanw]

I hit this bug in a pretty simple use case. Using wgpu 24.0 and vulkan 1.4.303 on Linux.

fn foobar(normals: array<vec3f, 12>, count: u32) -> QEFResult {
        for (var i = 0u; i < count; i++) {
                var n0 = normals[i];
        }

        for (var j = 0u; j < count; j++) {
                var n1 = normals[j];
        }

        return QEFResult(0.0, vec3(0.0));
}

Was easy to work around by assigning normals to a var and using that instead.