[SPIR-V] Add descriptor heap -fvk-resource-heap-stride / -fvk-sampler-heap-stride CLI flags

[Jonathan Zakharov (jzakharovnv)]

Building off of #8518, this PR adds two new command-line flags that override the ArrayStride of the descriptor heap runtime arrays emitted by -fspv-use-descriptor-heap. It is part 3/4 in a series.

-fvk-resource-heap-stride and -fvk-sampler-heap-stride sets the stride for ResourceDescriptorHeap SamplerDescriptorHeap arrays respectively. N and M must be a power of two in [8, 256]. When set, the CLI value takes the highest precedence.

Assisted by an AI agent.

Diego Novillo (@dnovillo)

[github-actions]

✅ With the latest revision this PR passed the C/C++ code formatter.

[Jonathan Zakharov (jzakharovnv)]

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[Diego Novillo (dnovillo)]

Thanks for the fixes. LGTM now.

[Damyan Pepper (damyanp)]

[Auto-generated note from Damyan Pepper (@damyanp)]

This looks like a user-visible bug fix/feature change. Please add (or point to) the corresponding entry in docs/ReleaseNotes.md.

If release-note coverage is planned in a related PR (including one that hasn’t been submitted yet), please mention that plan/link so we can avoid duplicate notes.

[Copilot]

Pull request overview

Adds configurable resource and sampler descriptor-heap strides while expanding native SPV_EXT_descriptor_heap lowering.

Changes:

• Adds and validates the two stride CLI options.
• Supports literal and computed descriptor-array strides, including acceleration structures.
• Expands documentation and SPIR-V regression coverage.

Reviewed changes

Copilot reviewed 57 out of 57 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
tools/clang/unittests/SPIRV/SpirvContextTest.cpp	Tests runtime-array uniquing.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.typed-formats.hlsl	Tests typed image formats.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.texturecube.hlsl	Tests cube textures.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.texture.hlsl	Tests buffer textures.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.texture-sampler-assignment.hlsl	Tests texture/sampler reassignment.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.texture-ms.hlsl	Tests multisampled textures.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.texture-dims.hlsl	Tests sampled texture dimensions.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.structured-buffer-atomic.hlsl	Tests structured-buffer atomics.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.stride-cli.hlsl	Tests literal CLI strides.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.stride-cli-permute.hlsl	Tests stride values and validation.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.static-global.hlsl	Tests static resource aliases.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.sampler-comparison.hlsl	Tests comparison samplers.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.sample-grad-bias.hlsl	Tests gradient and bias sampling.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.rwtexture-dims.hlsl	Tests storage texture dimensions.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.rwtexture-atomics.hlsl	Tests untyped image atomics.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.rwbyteaddressbuffer.hlsl	Tests writable byte buffers.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.nonuniform.hlsl	Tests divergent heap indexing.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.mixed-bound.hlsl	Tests bound/heap coexistence.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.mixed-alias.error.hlsl	Tests mixed-alias diagnostics.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.load-offset.hlsl	Tests texture-load offsets.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.groupshared.hlsl	Tests groupshared interoperability.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.gather.hlsl	Tests texture gathers.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.function-params.hlsl	Tests resource parameters.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.discarded.error.hlsl	Tests discarded-access diagnostics.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.counter-ops.error.hlsl	Tests unsupported counter diagnostics.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.constant-texture-buffer.hlsl	Tests constant/texture buffers.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.constant-buffer-assignment.hlsl	Tests constant-buffer reassignment.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.buffer.hlsl	Tests buffer heap lowering.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.array-stride.hlsl	Tests computed default strides.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.array-stride.accelstruct.hlsl	Tests acceleration-structure strides.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.append-consume.error.hlsl	Tests append/consume diagnostics.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.acceleration-structure.stride.error.hlsl	Tests acceleration-stride errors.
tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.acceleration-structure.hlsl	Tests acceleration-structure loads.
tools/clang/test/CodeGenSPIRV/resource-heap-ext-texture.hlsl	Removes superseded coverage.
tools/clang/lib/SPIRV/SpirvType.cpp	Includes stride IDs in type equality.
tools/clang/lib/SPIRV/SpirvInstruction.cpp	Implements new SPIR-V instructions.
tools/clang/lib/SPIRV/SpirvEmitter.h	Declares descriptor-heap helpers/state.
tools/clang/lib/SPIRV/SpirvEmitter.cpp	Implements native heap lowering and strides.
tools/clang/lib/SPIRV/SpirvContext.cpp	Uniques extended descriptor types.
tools/clang/lib/SPIRV/SpirvBuilder.cpp	Builds computed heap strides.
tools/clang/lib/SPIRV/LowerTypeVisitor.cpp	Lowers untyped image pointers.
tools/clang/lib/SPIRV/EmitVisitor.h	Declares new emission handlers.
tools/clang/lib/SPIRV/EmitVisitor.cpp	Emits new types, constants, and decorations.
tools/clang/lib/SPIRV/DeclResultIdMapper.h	Declares function alias support.
tools/clang/lib/SPIRV/DeclResultIdMapper.cpp	Implements function aliases.
tools/clang/lib/SPIRV/CapabilityVisitor.cpp	Requires Vulkan 1.3 for native heaps.
tools/clang/lib/SPIRV/AstTypeProbe.cpp	Detects acceleration structures.
tools/clang/include/clang/SPIRV/SpirvVisitor.h	Extends visitor dispatch.
tools/clang/include/clang/SPIRV/SpirvType.h	Stores runtime-array stride IDs.
tools/clang/include/clang/SPIRV/SpirvInstruction.h	Defines new instruction classes.
tools/clang/include/clang/SPIRV/SpirvContext.h	Exposes extended type uniquing.
tools/clang/include/clang/SPIRV/SpirvBuilder.h	Exposes stride construction APIs.
tools/clang/include/clang/SPIRV/AstTypeProbe.h	Declares acceleration-type detection.
lib/DxcSupport/HLSLOptions.cpp	Parses and validates stride options.
include/dxc/Support/SPIRVOptions.h	Stores stride overrides.
include/dxc/Support/HLSLOptions.td	Defines the CLI flags.
docs/SPIR-V.rst	Documents native heaps and strides.

[Copilot]

Pull request overview

Copilot reviewed 64 out of 64 changed files in this pull request and generated 2 comments.

Suppressed comments (2)

lib/DxcSupport/HLSLOptions.cpp:1221

• When both flags are invalid, these two handlers write to the same stream without a separator, producing a merged diagnostic such as ...got 48-fvk-sampler-heap-stride.... Insert a newline before reporting the sampler error when the resource validation already failed so the promised two diagnostics remain readable.

  bool strideOk = true;
  strideOk &= handleHeapStride(Args, OPT_fvk_resource_heap_stride,
                               &opts.SpirvOptions.resourceHeapStride,
                               "-fvk-resource-heap-stride", errors);
  strideOk &= handleHeapStride(Args, OPT_fvk_sampler_heap_stride,
                               &opts.SpirvOptions.samplerHeapStride,
                               "-fvk-sampler-heap-stride", errors);

tools/clang/test/CodeGenSPIRV/sm6_6.descriptorheap.ext.stride-cli-permute.hlsl:2

• Every positive RUN sets both overrides, so the documented independent fallback behavior is not covered: resource-only should retain ArrayStrideIdEXT for samplers, and sampler-only should retain it for resources. Add those two cases; the full cross-product cannot catch accidentally suppressing the default stride for the unconfigured heap.

[Copilot]

Pull request overview

Copilot reviewed 64 out of 64 changed files in this pull request and generated 2 comments.

Suppressed comments (1)

tools/clang/lib/SPIRV/SpirvEmitter.cpp:3075

• Direct buffer heap expressions bypass the new alias-only rejection. For example, returning ResourceDescriptorHeap[i] from a function whose result is StructuredBuffer enters this branch, then loadIfGLValue loads the whole buffer resource through the OpBufferPointerEXT pointer—the same invalid SPIR-V that lines 3077–3083 describe for an alias. Reject direct buffer-like heap returns before lowering them as well.

        const Expr *parentExpr = cast<CastExpr>(parentMap->getParent(srcExpr));
        QualType resourceType = parentExpr->getType();
        const auto *declRefExpr = dyn_cast<DeclRefExpr>(base->IgnoreCasts());
        declIdMapper.createResourceHeap(cast<VarDecl>(declRefExpr->getDecl()),
                                        resourceType);