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Merged
manon-traverse merged 3 commits into from
May 7, 2026
Merged

Move dispatch dimensions and vertex count to new DispatchParameters with defaults #1153

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b820ce9
Introduce DispatchParams. Allow more flexibility and introduce useful…
manon-traverse May 5, 2026
3de99f6
Add validation for specified DispatchParameters.
manon-traverse May 5, 2026
6340759
Add a comment explaning that DispatchGroupCount can be omitted and wh…
manon-traverse May 7, 2026
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3 changes: 2 additions & 1 deletion README.md
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Expand Up @@ -104,7 +104,8 @@ This framework provides a YAML representation for describing GPU pipelines and b
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
DispatchParameters:
DispatchGroupCount: [2, 1, 1] # Define how many groups to dispatch, if omitted one group is launched.
Buffers:
- Name: Constants
Format: Int32
Expand Down
27 changes: 22 additions & 5 deletions include/Support/Pipeline.h
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Expand Up @@ -355,10 +355,6 @@ struct IOBindings {
Stride += VA.size();
return Stride;
}

uint32_t getVertexCount() const {
return VertexBufferPtr->size() / getVertexStride();
}
};

// Describes a contiguous group of bytes in a push constant block.
Expand Down Expand Up @@ -400,10 +396,14 @@ struct Shader {
std::string Entry;
std::unique_ptr<llvm::MemoryBuffer> Shader;
std::unique_ptr<llvm::MemoryBuffer> Reflection;
int DispatchSize[3];
llvm::SmallVector<SpecializationConstant> SpecializationConstants;
};

struct DispatchParametersSet {
std::array<uint32_t, 3> DispatchGroupCount = {1, 1, 1};
std::optional<uint32_t> VertexCount;
};

struct Pipeline {
ShaderPipelineKind Kind;
llvm::SmallVector<Shader> Shaders;
Expand All @@ -415,6 +415,17 @@ struct Pipeline {
llvm::SmallVector<Sampler> Samplers;
llvm::SmallVector<Result> Results;
llvm::SmallVector<DescriptorSet> Sets;
DispatchParametersSet DispatchParameters;

uint32_t getVertexCount() const {
if (DispatchParameters.VertexCount)
return *DispatchParameters.VertexCount;

assert(Bindings.VertexBufferPtr != nullptr &&
"No VertexCount specified and no Vertex Buffer available to imply "
"VertexCount from.");
return Bindings.VertexBufferPtr->size() / Bindings.getVertexStride();
}

uint32_t getDescriptorCount() const {
uint32_t DescriptorCount = 0;
Expand Down Expand Up @@ -446,6 +457,7 @@ struct Pipeline {
}

llvm::Error validatePipelineKind();
llvm::Error validateDispatchParameters();

bool isCompute() const { return Kind == ShaderPipelineKind::Compute; }
bool isTraditionalRaster() const {
Expand All @@ -465,6 +477,7 @@ LLVM_YAML_IS_SEQUENCE_VECTOR(offloadtest::VertexAttribute)
LLVM_YAML_IS_SEQUENCE_VECTOR(offloadtest::SpecializationConstant)
LLVM_YAML_IS_SEQUENCE_VECTOR(offloadtest::PushConstantBlock)
LLVM_YAML_IS_SEQUENCE_VECTOR(offloadtest::PushConstantValue)
LLVM_YAML_IS_SEQUENCE_VECTOR(offloadtest::DispatchParametersSet)

namespace llvm {
namespace yaml {
Expand Down Expand Up @@ -513,6 +526,10 @@ template <> struct MappingTraits<offloadtest::PushConstantBlock> {
static void mapping(IO &I, offloadtest::PushConstantBlock &B);
};

template <> struct MappingTraits<offloadtest::DispatchParametersSet> {
static void mapping(IO &I, offloadtest::DispatchParametersSet &B);
};

template <> struct MappingTraits<offloadtest::VertexAttribute> {
static void mapping(IO &I, offloadtest::VertexAttribute &A);
};
Expand Down
10 changes: 5 additions & 5 deletions lib/API/DX/Device.cpp
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Expand Up @@ -1787,10 +1787,10 @@ class DXDevice : public offloadtest::Device {
if (!EncoderOrErr)
return EncoderOrErr.takeError();
auto &Encoder = *EncoderOrErr.get();
const llvm::ArrayRef<int> DispatchSize =
llvm::ArrayRef<int>(P.Shaders[0].DispatchSize);
if (auto Err = Encoder.dispatch(DispatchSize[0], DispatchSize[1],
DispatchSize[2]))
if (auto Err =
Encoder.dispatch(P.DispatchParameters.DispatchGroupCount[0],
P.DispatchParameters.DispatchGroupCount[1],
P.DispatchParameters.DispatchGroupCount[2]))
return Err;
Encoder.endEncoding();
}
Expand Down Expand Up @@ -2027,7 +2027,7 @@ class DXDevice : public offloadtest::Device {
static_cast<LONG>(VP.Height)};
IS.CB->CmdList->RSSetScissorRects(1, &Scissor);

IS.CB->CmdList->DrawInstanced(P.Bindings.getVertexCount(), 1, 0, 0);
IS.CB->CmdList->DrawInstanced(P.getVertexCount(), 1, 0, 0);

// Transition the render target to copy source and copy to the readback
// buffer.
Expand Down
9 changes: 4 additions & 5 deletions lib/API/MTL/MTLDevice.cpp
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Expand Up @@ -594,10 +594,9 @@ class MTLDevice : public offloadtest::Device {
}
Encoder.setThreadGroupSize(TGS[0], TGS[1], TGS[2]);

const llvm::ArrayRef<int> DispatchSize =
llvm::ArrayRef<int>(P.Shaders[0].DispatchSize);
if (auto Err =
Encoder.dispatch(DispatchSize[0], DispatchSize[1], DispatchSize[2]))
if (auto Err = Encoder.dispatch(P.DispatchParameters.DispatchGroupCount[0],
P.DispatchParameters.DispatchGroupCount[1],
P.DispatchParameters.DispatchGroupCount[2]))
return Err;
Encoder.endEncoding();
return llvm::Error::success();
Expand Down Expand Up @@ -718,7 +717,7 @@ class MTLDevice : public offloadtest::Device {
CmdEncoder->setVertexBuffer(llvm::cast<MTLBuffer>(*IS.VB).Buf, 0, 0);

CmdEncoder->drawPrimitives(MTL::PrimitiveTypeTriangle, NS::UInteger(0),
P.Bindings.getVertexCount());
P.getVertexCount());

CmdEncoder->endEncoding();

Expand Down
18 changes: 10 additions & 8 deletions lib/API/VK/Device.cpp
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Expand Up @@ -2724,22 +2724,24 @@ class VulkanDevice : public offloadtest::Device {
if (!EncoderOrErr)
return EncoderOrErr.takeError();
auto &Encoder = *EncoderOrErr.get();
const llvm::ArrayRef<int> DispatchSize =
llvm::ArrayRef<int>(P.Shaders[0].DispatchSize);
if (auto Err = Encoder.dispatch(DispatchSize[0], DispatchSize[1],
DispatchSize[2]))
if (auto Err =
Encoder.dispatch(P.DispatchParameters.DispatchGroupCount[0],
P.DispatchParameters.DispatchGroupCount[1],
P.DispatchParameters.DispatchGroupCount[2]))
return Err;
Encoder.endEncoding();
llvm::outs() << "Dispatched compute shader: { " << DispatchSize[0] << ", "
<< DispatchSize[1] << ", " << DispatchSize[2] << " }\n";
llvm::outs() << "Dispatched compute shader: { "
<< P.DispatchParameters.DispatchGroupCount[0] << ", "
<< P.DispatchParameters.DispatchGroupCount[1] << ", "
<< P.DispatchParameters.DispatchGroupCount[2] << " }\n";
} else {
VkDeviceSize Offsets[1]{0};
assert(IS.VB);
VkBuffer VBHandle = llvm::cast<VulkanBuffer>(*IS.VB).Buffer;
vkCmdBindVertexBuffers(IS.CB->CmdBuffer, 0, 1, &VBHandle, Offsets);
// instanceCount must be >=1 to draw; previously was 0 which draws nothing
vkCmdDraw(IS.CB->CmdBuffer, P.Bindings.getVertexCount(), 1, 0, 0);
llvm::outs() << "Drew " << P.Bindings.getVertexCount() << " vertices.\n";
vkCmdDraw(IS.CB->CmdBuffer, P.getVertexCount(), 1, 0, 0);
llvm::outs() << "Drew " << P.getVertexCount() << " vertices.\n";
vkCmdEndRenderPass(IS.CB->CmdBuffer);
copyTextureToReadback(IS.CB->CmdBuffer,
llvm::cast<VulkanTexture>(*IS.RenderTarget),
Expand Down
37 changes: 30 additions & 7 deletions lib/Support/Pipeline.cpp
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Expand Up @@ -53,6 +53,10 @@ void MappingTraits<offloadtest::Pipeline>::mapping(IO &I,
I.mapOptional("Bindings", P.Bindings);
I.mapOptional("PushConstants", P.PushConstants);

I.mapOptional("DispatchParameters", P.DispatchParameters);
if (auto Err = P.validateDispatchParameters())
I.setError(llvm::toString(std::move(Err)));

if (!I.outputting()) {
for (auto &D : P.Sets) {
for (auto &R : D.Resources) {
Expand Down Expand Up @@ -464,6 +468,12 @@ void MappingTraits<offloadtest::PushConstantValue>::mapping(
}
}

void MappingTraits<offloadtest::DispatchParametersSet>::mapping(
IO &I, offloadtest::DispatchParametersSet &Set) {
I.mapOptional("DispatchGroupCount", Set.DispatchGroupCount);
I.mapOptional("VertexCount", Set.VertexCount);
}

void MappingTraits<offloadtest::OutputProperties>::mapping(
IO &I, offloadtest::OutputProperties &P) {
I.mapRequired("Height", P.Height);
Expand Down Expand Up @@ -516,13 +526,6 @@ void MappingTraits<offloadtest::Shader>::mapping(IO &I,
I.mapRequired("Stage", S.Stage);
I.mapRequired("Entry", S.Entry);
I.mapOptional("SpecializationConstants", S.SpecializationConstants);

if (S.Stage == Stages::Compute) {
// Stage-specific data, not sure if this should be optional
// or moved into the Shaders structure.
MutableArrayRef<int> MutableDispatchSize(S.DispatchSize);
I.mapRequired("DispatchSize", MutableDispatchSize);
}
}

void MappingTraits<offloadtest::Result>::mapping(IO &I,
Expand Down Expand Up @@ -589,3 +592,23 @@ llvm::Error offloadtest::Pipeline::validatePipelineKind() {
return llvm::createStringError(
"The pipeline misses a Compute or Vertex Shader.");
}

llvm::Error offloadtest::Pipeline::validateDispatchParameters() {
switch (Kind) {
case ShaderPipelineKind::Compute:
if (DispatchParameters.VertexCount)
return llvm::createStringError(
"DispatchParameters.VertexCount set on a Compute pipeline. Only "
"allowed on a TraditionalRaster pipeline.");
break;
case ShaderPipelineKind::TraditionalRaster:
if (DispatchParameters.DispatchGroupCount !=
std::array<uint32_t, 3>{1, 1, 1})
return llvm::createStringError(
"DispatchParameters.DispatchGroupCount set on a TraditionalRaster "
"pipeline. Only allowed on a Compute pipeline.");
break;
Comment on lines +604 to +610
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@MarijnS95 MarijnS95 May 7, 2026

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Should we validate that VertexCount is not set if a vertex buffer was provided, or are there sensible reasons to override the "default" number of vertices in a buffer?

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@manon-traverse manon-traverse May 7, 2026

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There are valid reasons to specify this manually even though you have defined a vertex buffer. Especially when we start passing arguments like FirstVertex.

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@MarijnS95 MarijnS95 May 7, 2026

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The only validation would be if FirstVertex + VertexCount <= NumVerticesInBuffer perhaps?

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@manon-traverse manon-traverse May 7, 2026

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Technically that would still be a valid case though, but you would be reading zeroes.

}

return llvm::Error::success();
}
1 change: 0 additions & 1 deletion test/Basic/DescriptorSets.test
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Expand Up @@ -14,7 +14,6 @@ void main(uint GI : SV_GroupIndex) {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Float32
Expand Down
3 changes: 2 additions & 1 deletion test/Basic/Mandelbrot.test
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Expand Up @@ -57,7 +57,8 @@ const static int Dimension = 4096;
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [16384, 1, 1]
DispatchParameters:
DispatchGroupCount: [16384, 1, 1]
Buffers:
- Name: Tex
Format: Float32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_const_single_subscript.i2x3.test
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Expand Up @@ -31,7 +31,6 @@ void main() {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Int32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_const_single_subscript.test
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Expand Up @@ -28,7 +28,6 @@ void main() {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Int32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_construct_by_sub_mat.test
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Expand Up @@ -27,7 +27,6 @@ void main(uint GI : SV_GroupIndex) {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Int32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_elementwise_cast.test
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Expand Up @@ -37,7 +37,6 @@ void main(uint GI : SV_GroupIndex) {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Float32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_elementwise_vector_cast.test
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Expand Up @@ -21,7 +21,6 @@ void main(uint GI : SV_GroupIndex) {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Float32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_groupthread_swizzle_one_based.test
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Expand Up @@ -59,7 +59,6 @@ void main(uint GI : SV_GroupIndex) {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Int32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_groupthread_swizzle_zero_based.test
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Expand Up @@ -59,7 +59,6 @@ void main(uint GI : SV_GroupIndex) {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Int32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_m-based_getter.test
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Expand Up @@ -58,7 +58,6 @@ void main() {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Float32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_m-based_setter.test
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Expand Up @@ -119,7 +119,6 @@ void main() {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Float32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_m-based_swizzle_getter.test
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Expand Up @@ -44,7 +44,6 @@ void main() {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Float32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_one-based_getter.test
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Expand Up @@ -59,7 +59,6 @@ void main() {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Float32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_one-based_setter.test
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Expand Up @@ -80,7 +80,6 @@ void main() {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Float32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_one-based_swizzle_getter.test
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Expand Up @@ -36,7 +36,6 @@ void main() {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Float32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_scalar_arithmetic.test
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Expand Up @@ -26,7 +26,6 @@ void main(uint GI : SV_GroupIndex) {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Int32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_scalar_constructor.test
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Expand Up @@ -21,7 +21,6 @@ void main(uint GI : SV_GroupIndex) {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Int32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_single_subscript_basic.i2x3.test
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Expand Up @@ -31,7 +31,6 @@ void main() {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Int32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_single_subscript_basic.i3x2.test
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Expand Up @@ -35,7 +35,6 @@ void main() {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Int32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_single_subscript_basic.test
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Expand Up @@ -37,7 +37,6 @@ void main() {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Int32
Expand Down
1 change: 0 additions & 1 deletion test/Basic/Matrix/matrix_single_subscript_load.test
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Expand Up @@ -29,7 +29,6 @@ void main() {
Shaders:
- Stage: Compute
Entry: main
DispatchSize: [1, 1, 1]
Buffers:
- Name: In
Format: Int32
Expand Down
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