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Add vulkanMemoryModel #965
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Add vulkanMemoryModel #965
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What about places where we insert spirv ops earlier in the flow? I feel like there may be cases of missed operands.
lib/Compiler.cpp
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if (clspv::Option::VulkanMemoryModel() && | ||
clspv::Option::SpvVersion() < clspv::Option::SPIRVVersion::SPIRV_1_5) { | ||
llvm::errs() << "vulkan memory model is not supported for spirv versions " | ||
"less that 1.5\n"; | ||
return -1; | ||
} |
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The OpExtension is required prior to 1.5, but the functionality is available so this error can be dropped.
lib/SPIRVProducerPass.cpp
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; | ||
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if (clspv::Option::VulkanMemoryModel()) { | ||
addSPIRVInst<kExtensions>(spv::OpExtension, "SPV_KHR_vulkan_memory_model"); |
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The extension is only required if the version is < 1.5
lib/SPIRVProducerPass.cpp
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@@ -6300,6 +6402,22 @@ bool SPIRVProducerPassImpl::isPointerUniform(Value *ptr) { | |||
return uniformPointer; | |||
} | |||
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bool SPIRVProducerPassImpl::isCoherentResource(Value *Ptr) { |
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This seems like it will fail if the address calculation includes a phi, select, or function parameter. Previously those cases would all have been covered by the coherent decoration.
lib/SPIRVProducerPass.cpp
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addSPIRVInst<kCapabilities>(spv::OpCapability, | ||
spv::CapabilityVulkanMemoryModelDeviceScopeKHR); |
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It's not clear to me that we'd want device scope by default. I think QueueFamily is probably more appropriate. I'd suggest you take a look at clvk, but I expect it doesn't use different families.
This could be an extra command line option. Probably you'd want to introduce a helper function to get the right scope.
// CHECK-NOT: OpDecorate {{.*}} Coherent | ||
// CHECK: [[uint:%[_a-zA-Z0-9]+]] = OpTypeInt 32 0 | ||
// CHECK: [[DEVICE_SCOPE:%[_a-zA-Z0-9]+]] = OpConstant [[uint]] 1 | ||
// CHECK: {{.*}} = OpLoad [[uint]] {{.*}} MakePointerVisible|NonPrivatePointer [[DEVICE_SCOPE]] |
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What about the store in bar
. If x
is selected it should be coherent.
lib/SPIRVProducerPass.cpp
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const auto coherent = | ||
unsigned(dyn_cast<ConstantInt>( | ||
Call->getArgOperand(ClspvOperand::kResourceCoherent)) | ||
->getZExtValue()); | ||
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if (clspv::Option::VulkanMemoryModel() && coherent == 1) { | ||
Ops << (spv::MemoryAccessNonPrivatePointerMask | | ||
spv::MemoryAccessMakePointerVisibleMask) | ||
<< getSPIRVInt32Constant(spv::ScopeDevice); | ||
} |
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I think this is always unnecessary. These loads occur for samplers and images. Those handle loads come from UniformConstant
and the handles themselves are never modified.
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bool isCoherent = isCoherentResource(Call->getArgOperand(0)); | ||
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if (clspv::Option::VulkanMemoryModel() && isCoherent) { |
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I don't see any coverage of this in the tests. In fact, I'm not sure clspv can generate a coherent image right now. That is likely a bug since where this functionality wasn't updated for read_write images. It would need a change in descriptor allocation. Please either fix that or file an issue to address it.
Separately, this could be tested using IR only. Take a look at the tests in Spv1p4 for how to run SPIRVProducer only tests.
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bool isCoherent = isCoherentResource(Call->getArgOperand(0)); | ||
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if (clspv::Option::VulkanMemoryModel() && isCoherent) { |
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Same as above, please add unit test coverage.
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Is there a plan to move forward with this PR? I am working on a tool to verify SPIRV wrt the vulkan memory model and having clspv generate such kind of code would be super useful. I wanted to test the code in this PR, but unfortunately it does not build for me. |
We'd like to eventually finish this, but I can't commit to a time frame when that might occur. In the meantime, you should be able to get equivalent functionality by the SPIRV-Tools optimizer using |
Thanks @alan-baker, this was super useful! |
PR Changes
vulkan-memory-model
option to clspvAvailable
andVisible
on read and write instructionsRelated issue
This contribution is being made by Codeplay on behalf of Samsung.