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hal: limit binding sizes to i32 #2363

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Jan 6, 2022
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hal: limit binding sizes to i32 #2363

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6 changes: 6 additions & 0 deletions wgpu-hal/src/auxil/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,12 @@ pub mod db {
}
}

/// Maximum binding size for the shaders that only support `i32` indexing.
/// Interestingly, the index itself can't reach that high, because the minimum
/// element size is 4 bytes, but the compiler toolchain still computes the
/// offset at some intermediate point, internally, as i32.
pub const MAX_I32_BINDING_SIZE: u32 = 1 << 31;
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I may miss something, but 1 << 31 does not fit in an i32, as the maximum value for it is (1 << 31) - 1.

I think that using i32::MAX as u32 instead could be less error-prone.

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The size doesn't need to fit into i32. It's the byte offsets that are internally converted into i32, and they are strictly less than the full binding size.


pub fn map_naga_stage(stage: naga::ShaderStage) -> wgt::ShaderStages {
match stage {
naga::ShaderStage::Vertex => wgt::ShaderStages::VERTEX,
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2 changes: 1 addition & 1 deletion wgpu-hal/src/dx12/adapter.rs
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Expand Up @@ -240,7 +240,7 @@ impl super::Adapter {
max_uniform_buffers_per_shader_stage: full_heap_count,
max_uniform_buffer_binding_size: d3d12::D3D12_REQ_CONSTANT_BUFFER_ELEMENT_COUNT
* 16,
max_storage_buffer_binding_size: !0,
max_storage_buffer_binding_size: crate::auxil::MAX_I32_BINDING_SIZE,
max_vertex_buffers: d3d12::D3D12_VS_INPUT_REGISTER_COUNT
.min(crate::MAX_VERTEX_BUFFERS as u32),
max_vertex_attributes: d3d12::D3D12_IA_VERTEX_INPUT_RESOURCE_SLOT_COUNT,
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8 changes: 6 additions & 2 deletions wgpu-hal/src/vulkan/adapter.rs
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Expand Up @@ -708,8 +708,12 @@ impl PhysicalDeviceCapabilities {
max_storage_buffers_per_shader_stage: max_storage_buffers,
max_storage_textures_per_shader_stage: max_storage_textures,
max_uniform_buffers_per_shader_stage: max_uniform_buffers,
max_uniform_buffer_binding_size: limits.max_uniform_buffer_range,
max_storage_buffer_binding_size: limits.max_storage_buffer_range,
max_uniform_buffer_binding_size: limits
.max_uniform_buffer_range
.min(crate::auxil::MAX_I32_BINDING_SIZE),
max_storage_buffer_binding_size: limits
.max_storage_buffer_range
.min(crate::auxil::MAX_I32_BINDING_SIZE),
max_vertex_buffers: limits
.max_vertex_input_bindings
.min(crate::MAX_VERTEX_BUFFERS as u32),
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