(Naga) Add support for Descriptor Runtime Indexing when ingesting SPIR-V (#8256)

CHANGELOG.md

@@ -198,6 +198,7 @@ By @cwfitzgerald in [#8162](https://github.com/gfx-rs/wgpu/pull/8162).
 - For custom Naga backend authors: `naga::proc::Namer` now accepts reserved keywords using two new dedicated types, `proc::{KeywordSet, CaseInsensitiveKeywordSet}`. By @kpreid in [#8136](https://github.com/gfx-rs/wgpu/pull/8136).
 - **BREAKING**: Previously the WGSL storage-texture format `rg11b10float` was incorrectly accepted and generated by naga, but now only accepts the the correct name `rg11b10ufloat` instead. By @ErikWDev in [#8219](https://github.com/gfx-rs/wgpu/pull/8219).
 - The [`source()`](https://doc.rust-lang.org/std/error/trait.Error.html#method.source) method of `ShaderError` no longer reports the error as its own source. By @andyleiserson in [#8258](https://github.com/gfx-rs/wgpu/pull/8258).
+- naga correctly ingests SPIR-V that use descriptor runtime indexing, which in turn is correctly converted into WGSLs binding array. By @hasenbanck in [8256](https://github.com/gfx-rs/wgpu/pull/8256).
 
 #### DX12
 

naga/src/front/spv/mod.rs

@@ -82,6 +82,7 @@ pub const SUPPORTED_CAPABILITIES: &[spirv::Capability] = &[
     spirv::Capability::GroupNonUniformBallot,
     spirv::Capability::GroupNonUniformShuffle,
     spirv::Capability::GroupNonUniformShuffleRelative,
+    spirv::Capability::RuntimeDescriptorArray,
     // tricky ones
     spirv::Capability::UniformBufferArrayDynamicIndexing,
     spirv::Capability::StorageBufferArrayDynamicIndexing,
@@ -90,6 +91,7 @@ pub const SUPPORTED_EXTENSIONS: &[&str] = &[
     "SPV_KHR_storage_buffer_storage_class",
     "SPV_KHR_vulkan_memory_model",
     "SPV_KHR_multiview",
+    "SPV_EXT_descriptor_indexing",
     "SPV_EXT_shader_atomic_float_add",
     "SPV_KHR_16bit_storage",
 ];

naga/tests/in/spv/binding-arrays.runtime.slang

@@ -0,0 +1,19 @@
+// Compiled with:
+// slangc -target spirv -profile spirv_1_5 -o naga/tests/in/spv/binding-arrays.runtime.spv naga/tests/in/spv/binding-arrays.runtime.slang
+// Disassembled with:
+// spirv-dis naga/tests/in/spv/binding-arrays.runtime.spv -o naga/tests/in/spv/binding-arrays.runtime.spvasm
+
+#language slang 2026
+
+[[vk::binding(0, 0)]] var textures: Texture2D[];
+[[vk::binding(1, 0)]] var linear_sampler: SamplerState;
+
+struct VertexOutput {
+    var texture_coordinates: float2;
+    var texture_index: uint;
+};
+
+[[shader("pixel")]]
+func main(input: VertexOutput) -> float4 {
+    return textures[input.texture_index].Sample(linear_sampler, input.texture_coordinates);
+}

naga/tests/in/spv/binding-arrays.runtime.spvasm

@@ -0,0 +1,60 @@
+; SPIR-V
+; Version: 1.5
+; Generator: Khronos Slang Compiler; 0
+; Bound: 33
+; Schema: 0
+               OpCapability RuntimeDescriptorArray
+               OpCapability Shader
+               OpMemoryModel Logical GLSL450
+               OpEntryPoint Fragment %main "main" %textures %linear_sampler %entryPointParam_main %input_texture_coordinates %input_texture_index
+               OpExecutionMode %main OriginUpperLeft
+               OpSource Slang 1
+               OpName %input_texture_coordinates "input.texture_coordinates"
+               OpName %input_texture_index "input.texture_index"
+               OpName %textures "textures"
+               OpName %linear_sampler "linear_sampler"
+               OpName %sampledImage "sampledImage"
+               OpName %sampled "sampled"
+               OpName %entryPointParam_main "entryPointParam_main"
+               OpName %main "main"
+               OpDecorate %input_texture_coordinates Location 0
+               OpDecorate %input_texture_index Location 1
+               OpDecorate %input_texture_index Flat
+               OpDecorate %textures Binding 0
+               OpDecorate %textures DescriptorSet 0
+               OpDecorate %linear_sampler Binding 1
+               OpDecorate %linear_sampler DescriptorSet 0
+               OpDecorate %entryPointParam_main Location 0
+       %void = OpTypeVoid
+          %3 = OpTypeFunction %void
+      %float = OpTypeFloat 32
+    %v2float = OpTypeVector %float 2
+%_ptr_Input_v2float = OpTypePointer Input %v2float
+       %uint = OpTypeInt 32 0
+%_ptr_Input_uint = OpTypePointer Input %uint
+         %15 = OpTypeImage %float 2D 2 0 0 1 Unknown
+%_runtimearr_15 = OpTypeRuntimeArray %15
+%_ptr_UniformConstant__runtimearr_15 = OpTypePointer UniformConstant %_runtimearr_15
+%_ptr_UniformConstant_15 = OpTypePointer UniformConstant %15
+         %22 = OpTypeSampler
+%_ptr_UniformConstant_22 = OpTypePointer UniformConstant %22
+         %26 = OpTypeSampledImage %15
+    %v4float = OpTypeVector %float 4
+%_ptr_Output_v4float = OpTypePointer Output %v4float
+%input_texture_coordinates = OpVariable %_ptr_Input_v2float Input
+%input_texture_index = OpVariable %_ptr_Input_uint Input
+   %textures = OpVariable %_ptr_UniformConstant__runtimearr_15 UniformConstant
+%linear_sampler = OpVariable %_ptr_UniformConstant_22 UniformConstant
+%entryPointParam_main = OpVariable %_ptr_Output_v4float Output
+       %main = OpFunction %void None %3
+          %4 = OpLabel
+          %7 = OpLoad %v2float %input_texture_coordinates
+         %11 = OpLoad %uint %input_texture_index
+         %19 = OpAccessChain %_ptr_UniformConstant_15 %textures %11
+         %21 = OpLoad %15 %19
+         %23 = OpLoad %22 %linear_sampler
+%sampledImage = OpSampledImage %26 %21 %23
+    %sampled = OpImageSampleImplicitLod %v4float %sampledImage %7 None
+               OpStore %entryPointParam_main %sampled
+               OpReturn
+               OpFunctionEnd

naga/tests/in/spv/binding-arrays.runtime.toml

@@ -0,0 +1,4 @@
+god_mode = true
+
+[spv-in]
+adjust_coordinate_space = true

naga/tests/out/wgsl/spv-binding-arrays.runtime.wgsl

@@ -0,0 +1,24 @@
+var<private> inputtexture_coordinates_1: vec2<f32>;
+var<private> inputtexture_index_1: u32;
+@group(0) @binding(0) 
+var textures: binding_array<texture_2d<f32>>;
+@group(0) @binding(1) 
+var linear_sampler: sampler;
+var<private> entryPointParam_main: vec4<f32>;
+
+fn main_1() {
+    let _e5 = inputtexture_coordinates_1;
+    let _e6 = inputtexture_index_1;
+    let _e8 = textureSample(textures[_e6], linear_sampler, _e5);
+    entryPointParam_main = _e8;
+    return;
+}
+
+@fragment 
+fn main(@location(0) inputtexture_coordinates: vec2<f32>, @location(1) @interpolate(flat) inputtexture_index: u32) -> @location(0) vec4<f32> {
+    inputtexture_coordinates_1 = inputtexture_coordinates;
+    inputtexture_index_1 = inputtexture_index;
+    main_1();
+    let _e5 = entryPointParam_main;
+    return _e5;
+}