Backport #3798 to 0.16 (DX12 increase `max_storage_buffers/textures_p…

…er_shader_stage`) (#3891)

CHANGELOG.md

@@ -40,6 +40,12 @@ Bottom level categories:
 
 ## Unreleased
 
+### Changes
+
+#### DX12
+
+- Increase the `max_storage_buffers_per_shader_stage` and `max_storage_textures_per_shader_stage` limits based on what the hardware supports. by @Elabajaba in [#3798]https://github.com/gfx-rs/wgpu/pull/3798
+
 ## v0.16.1 (2023-05-24)
 
 ### Bug Fixes

wgpu-hal/src/dx12/adapter.rs

@@ -74,6 +74,29 @@ impl super::Adapter {
 
  profiling::scope!("feature queries");
 
+ // Detect the highest supported feature level.
+ let d3d_feature_level = [
+ d3d12::FeatureLevel::L12_1,
+ d3d12::FeatureLevel::L12_0,
+ d3d12::FeatureLevel::L11_1,
+ d3d12::FeatureLevel::L11_0,
+ ];
+ let mut device_levels: d3d12_ty::D3D12_FEATURE_DATA_FEATURE_LEVELS =
+ unsafe { mem::zeroed() };
+ device_levels.NumFeatureLevels = d3d_feature_level.len() as u32;
+ device_levels.pFeatureLevelsRequested = d3d_feature_level.as_ptr().cast();
+ unsafe {
+ device.CheckFeatureSupport(
+ d3d12_ty::D3D12_FEATURE_FEATURE_LEVELS,
+ &mut device_levels as *mut _ as *mut _,
+ mem::size_of::<d3d12_ty::D3D12_FEATURE_DATA_FEATURE_LEVELS>() as _,
+ )
+ };
+ // This cast should never fail because we only requested feature levels that are already in the enum.
+ let max_feature_level =
+ d3d12::FeatureLevel::try_from(device_levels.MaxSupportedFeatureLevel)
+ .expect("Unexpected feature level");
+
  // We have found a possible adapter.
  // Acquire the device information.
  let mut desc: dxgi1_2::DXGI_ADAPTER_DESC2 = unsafe { mem::zeroed() };
@@ -182,11 +205,18 @@ impl super::Adapter {
  // Theoretically vram limited, but in practice 2^20 is the limit
  let tier3_practical_descriptor_limit = 1 << 20;
 
- let (full_heap_count, _uav_count) = match options.ResourceBindingTier {
- d3d12_ty::D3D12_RESOURCE_BINDING_TIER_1 => (
- d3d12_ty::D3D12_MAX_SHADER_VISIBLE_DESCRIPTOR_HEAP_SIZE_TIER_1,
- 8, // conservative, is 64 on feature level 11.1
- ),
+ let (full_heap_count, uav_count) = match options.ResourceBindingTier {
+ d3d12_ty::D3D12_RESOURCE_BINDING_TIER_1 => {
+ let uav_count = match max_feature_level {
+ d3d12::FeatureLevel::L11_0 => 8,
+ _ => 64,
+ };
+
+ (
+ d3d12_ty::D3D12_MAX_SHADER_VISIBLE_DESCRIPTOR_HEAP_SIZE_TIER_1,
+ uav_count,
+ )
+ }
  d3d12_ty::D3D12_RESOURCE_BINDING_TIER_2 => (
  d3d12_ty::D3D12_MAX_SHADER_VISIBLE_DESCRIPTOR_HEAP_SIZE_TIER_2,
  64,
@@ -284,9 +314,10 @@ impl super::Adapter {
  _ => d3d12_ty::D3D12_MAX_SHADER_VISIBLE_SAMPLER_HEAP_SIZE,
  },
  // these both account towards `uav_count`, but we can't express the limit as as sum
- max_storage_buffers_per_shader_stage: base.max_storage_buffers_per_shader_stage,
- max_storage_textures_per_shader_stage: base
- .max_storage_textures_per_shader_stage,
+ // of the two, so we divide it by 4 to account for the worst case scenario
+ // (2 shader stages, with both using 16 storage textures and 16 storage buffers)
+ max_storage_buffers_per_shader_stage: uav_count / 4,
+ max_storage_textures_per_shader_stage: uav_count / 4,
  max_uniform_buffers_per_shader_stage: full_heap_count,
  max_uniform_buffer_binding_size:
  d3d12_ty::D3D12_REQ_CONSTANT_BUFFER_ELEMENT_COUNT * 16,

wgpu-types/src/lib.rs

@@ -844,7 +844,7 @@ pub struct Limits {
  pub max_samplers_per_shader_stage: u32,
  /// Amount of storage buffers visible in a single shader stage. Defaults to 8. Higher is "better".
  pub max_storage_buffers_per_shader_stage: u32,
- /// Amount of storage textures visible in a single shader stage. Defaults to 8. Higher is "better".
+ /// Amount of storage textures visible in a single shader stage. Defaults to 4. Higher is "better".
  pub max_storage_textures_per_shader_stage: u32,
  /// Amount of uniform buffers visible in a single shader stage. Defaults to 12. Higher is "better".
  pub max_uniform_buffers_per_shader_stage: u32,