src/Pipeline/SpirvShaderMemory.cpp - SwiftShader - Git at Google

 // Copyright 2019 The SwiftShader Authors. All Rights Reserved.
 //
 // Licensed under the Apache License, Version 2.0 (the "License");
 // you may not use this file except in compliance with the License.
 // You may obtain a copy of the License at
 //
 //    http://www.apache.org/licenses/LICENSE-2.0
 //
 // Unless required by applicable law or agreed to in writing, software
 // distributed under the License is distributed on an "AS IS" BASIS,
 // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 // See the License for the specific language governing permissions and
 // limitations under the License.

 #include "SpirvShader.hpp"

 #include "ShaderCore.hpp"

 #include "Vulkan/VkPipelineLayout.hpp"

 #include <spirv/unified1/spirv.hpp>

 namespace sw {

 SpirvShader::EmitResult SpirvShader::EmitLoad(InsnIterator insn, EmitState *state) const
 {
 	bool atomic = (insn.opcode() == spv::OpAtomicLoad);
 	Object::ID resultId = insn.word(2);
 	Object::ID pointerId = insn.word(3);
 	auto &result = getObject(resultId);
 	auto &resultTy = getType(result.type);
 	auto &pointer = getObject(pointerId);
 	auto &pointerTy = getType(pointer.type);
 	std::memory_order memoryOrder = std::memory_order_relaxed;

 	ASSERT(getType(pointer.type).element == result.type);
 	ASSERT(Type::ID(insn.word(1)) == result.type);
 	ASSERT(!atomic || getType(getType(pointer.type).element).opcode() == spv::OpTypeInt);  // Vulkan 1.1: "Atomic instructions must declare a scalar 32-bit integer type, for the value pointed to by Pointer."

 	if(pointerTy.storageClass == spv::StorageClassUniformConstant)
 	{
 		// Just propagate the pointer.
 		auto &ptr = state->getPointer(pointerId);
 		state->createPointer(resultId, ptr);
 		return EmitResult::Continue;
 	}

 	if(atomic)
 	{
 		Object::ID semanticsId = insn.word(5);
 		auto memorySemantics = static_cast<spv::MemorySemanticsMask>(getObject(semanticsId).constantValue[0]);
 		memoryOrder = MemoryOrder(memorySemantics);
 	}

 	auto ptr = GetPointerToData(pointerId, 0, state);
 	bool interleavedByLane = IsStorageInterleavedByLane(pointerTy.storageClass);
 	auto &dst = state->createIntermediate(resultId, resultTy.sizeInComponents);
 	auto robustness = state->getOutOfBoundsBehavior(pointerTy.storageClass);

 	VisitMemoryObject(pointerId, [&](const MemoryElement &el) {
 		auto p = ptr + el.offset;
 		if(interleavedByLane) { p = InterleaveByLane(p); }  // TODO: Interleave once, then add offset?
 		dst.move(el.index, p.Load<SIMD::Float>(robustness, state->activeLaneMask(), atomic, memoryOrder));
 	});

 	return EmitResult::Continue;
 }

 SpirvShader::EmitResult SpirvShader::EmitStore(InsnIterator insn, EmitState *state) const
 {
 	bool atomic = (insn.opcode() == spv::OpAtomicStore);
 	Object::ID pointerId = insn.word(1);
 	Object::ID objectId = insn.word(atomic ? 4 : 2);
 	auto &object = getObject(objectId);
 	auto &pointer = getObject(pointerId);
 	auto &pointerTy = getType(pointer.type);
 	auto &elementTy = getType(pointerTy.element);
 	std::memory_order memoryOrder = std::memory_order_relaxed;

 	if(atomic)
 	{
 		Object::ID semanticsId = insn.word(3);
 		auto memorySemantics = static_cast<spv::MemorySemanticsMask>(getObject(semanticsId).constantValue[0]);
 		memoryOrder = MemoryOrder(memorySemantics);
 	}

 	ASSERT(!atomic || elementTy.opcode() == spv::OpTypeInt);  // Vulkan 1.1: "Atomic instructions must declare a scalar 32-bit integer type, for the value pointed to by Pointer."

 	auto ptr = GetPointerToData(pointerId, 0, state);
 	bool interleavedByLane = IsStorageInterleavedByLane(pointerTy.storageClass);
 	auto robustness = state->getOutOfBoundsBehavior(pointerTy.storageClass);

 	SIMD::Int mask = state->activeLaneMask();
 	if(!StoresInHelperInvocation(pointerTy.storageClass))
 	{
 		mask = mask & state->storesAndAtomicsMask();
 	}

 	if(object.kind == Object::Kind::Constant)
 	{
 		// Constant source data.
 		const uint32_t *src = object.constantValue.get();
 		VisitMemoryObject(pointerId, [&](const MemoryElement &el) {
 			auto p = ptr + el.offset;
 			if(interleavedByLane) { p = InterleaveByLane(p); }
 			p.Store(SIMD::Int(src[el.index]), robustness, mask, atomic, memoryOrder);
 		});
 	}
 	else
 	{
 		// Intermediate source data.
 		auto &src = state->getIntermediate(objectId);
 		VisitMemoryObject(pointerId, [&](const MemoryElement &el) {
 			auto p = ptr + el.offset;
 			if(interleavedByLane) { p = InterleaveByLane(p); }
 			p.Store(src.Float(el.index), robustness, mask, atomic, memoryOrder);
 		});
 	}

 	return EmitResult::Continue;
 }

 SpirvShader::EmitResult SpirvShader::EmitVariable(InsnIterator insn, EmitState *state) const
 {
 	auto routine = state->routine;
 	Object::ID resultId = insn.word(2);
 	auto &object = getObject(resultId);
 	auto &objectTy = getType(object.type);

 	switch(objectTy.storageClass)
 	{
 		case spv::StorageClassOutput:
 		case spv::StorageClassPrivate:
 		case spv::StorageClassFunction:
 		{
 			ASSERT(objectTy.opcode() == spv::OpTypePointer);
 			auto base = &routine->getVariable(resultId)[0];
 			auto elementTy = getType(objectTy.element);
 			auto size = elementTy.sizeInComponents * static_cast<uint32_t>(sizeof(float)) * SIMD::Width;
 			state->createPointer(resultId, SIMD::Pointer(base, size));
 			break;
 		}
 		case spv::StorageClassWorkgroup:
 		{
 			ASSERT(objectTy.opcode() == spv::OpTypePointer);
 			auto base = &routine->workgroupMemory[0];
 			auto size = workgroupMemory.size();
 			state->createPointer(resultId, SIMD::Pointer(base, size, workgroupMemory.offsetOf(resultId)));
 			break;
 		}
 		case spv::StorageClassInput:
 		{
 			if(object.kind == Object::Kind::InterfaceVariable)
 			{
 				auto &dst = routine->getVariable(resultId);
 				int offset = 0;
 				VisitInterface(resultId,
 				               [&](Decorations const &d, AttribType type) {
 					               auto scalarSlot = d.Location << 2 | d.Component;
 					               dst[offset++] = routine->inputs[scalarSlot];
 				               });
 			}
 			ASSERT(objectTy.opcode() == spv::OpTypePointer);
 			auto base = &routine->getVariable(resultId)[0];
 			auto elementTy = getType(objectTy.element);
 			auto size = elementTy.sizeInComponents * static_cast<uint32_t>(sizeof(float)) * SIMD::Width;
 			state->createPointer(resultId, SIMD::Pointer(base, size));
 			break;
 		}
 		case spv::StorageClassUniformConstant:
 		{
 			const auto &d = descriptorDecorations.at(resultId);
 			ASSERT(d.DescriptorSet >= 0);
 			ASSERT(d.Binding >= 0);

 			uint32_t arrayIndex = 0;  // TODO(b/129523279)
 			auto setLayout = routine->pipelineLayout->getDescriptorSetLayout(d.DescriptorSet);
 			if(setLayout->hasBinding(d.Binding))
 			{
 				uint32_t bindingOffset = static_cast<uint32_t>(setLayout->getBindingOffset(d.Binding, arrayIndex));
 				Pointer<Byte> set = routine->descriptorSets[d.DescriptorSet];  // DescriptorSet*
 				Pointer<Byte> binding = Pointer<Byte>(set + bindingOffset);    // vk::SampledImageDescriptor*
 				auto size = 0;                                                 // Not required as this pointer is not directly used by SIMD::Read or SIMD::Write.
 				state->createPointer(resultId, SIMD::Pointer(binding, size));
 			}
 			else
 			{
 				// TODO: Error if the variable with the non-existant binding is
 				// used? Or perhaps strip these unused variable declarations as
 				// a preprocess on the SPIR-V?
 			}
 			break;
 		}
 		case spv::StorageClassUniform:
 		case spv::StorageClassStorageBuffer:
 		{
 			const auto &d = descriptorDecorations.at(resultId);
 			ASSERT(d.DescriptorSet >= 0);
 			auto size = 0;  // Not required as this pointer is not directly used by SIMD::Read or SIMD::Write.
 			// Note: the module may contain descriptor set references that are not suitable for this implementation -- using a set index higher than the number
 			// of descriptor set binding points we support. As long as the selected entrypoint doesn't actually touch the out of range binding points, this
 			// is valid. In this case make the value nullptr to make it easier to diagnose an attempt to dereference it.
 			if(d.DescriptorSet < vk::MAX_BOUND_DESCRIPTOR_SETS)
 			{
 				state->createPointer(resultId, SIMD::Pointer(routine->descriptorSets[d.DescriptorSet], size));
 			}
 			else
 			{
 				state->createPointer(resultId, SIMD::Pointer(nullptr, 0));
 			}
 			break;
 		}
 		case spv::StorageClassPushConstant:
 		{
 			state->createPointer(resultId, SIMD::Pointer(routine->pushConstants, vk::MAX_PUSH_CONSTANT_SIZE));
 			break;
 		}
 		default:
 			UNREACHABLE("Storage class %d", objectTy.storageClass);
 			break;
 	}

 	if(insn.wordCount() > 4)
 	{
 		Object::ID initializerId = insn.word(4);
 		if(getObject(initializerId).kind != Object::Kind::Constant)
 		{
 			UNIMPLEMENTED("Non-constant initializers not yet implemented");
 		}
 		switch(objectTy.storageClass)
 		{
 			case spv::StorageClassOutput:
 			case spv::StorageClassPrivate:
 			case spv::StorageClassFunction:
 			{
 				bool interleavedByLane = IsStorageInterleavedByLane(objectTy.storageClass);
 				auto ptr = GetPointerToData(resultId, 0, state);
 				GenericValue initialValue(this, state, initializerId);
 				VisitMemoryObject(resultId, [&](const MemoryElement &el) {
 					auto p = ptr + el.offset;
 					if(interleavedByLane) { p = InterleaveByLane(p); }
 					auto robustness = OutOfBoundsBehavior::UndefinedBehavior;  // Local variables are always within bounds.
 					p.Store(initialValue.Float(el.index), robustness, state->activeLaneMask());
 				});
 				break;
 			}
 			default:
 				ASSERT_MSG(initializerId == 0, "Vulkan does not permit variables of storage class %d to have initializers", int(objectTy.storageClass));
 		}
 	}

 	return EmitResult::Continue;
 }

 SpirvShader::EmitResult SpirvShader::EmitCopyMemory(InsnIterator insn, EmitState *state) const
 {
 	Object::ID dstPtrId = insn.word(1);
 	Object::ID srcPtrId = insn.word(2);
 	auto &dstPtrTy = getType(getObject(dstPtrId).type);
 	auto &srcPtrTy = getType(getObject(srcPtrId).type);
 	ASSERT(dstPtrTy.element == srcPtrTy.element);

 	bool dstInterleavedByLane = IsStorageInterleavedByLane(dstPtrTy.storageClass);
 	bool srcInterleavedByLane = IsStorageInterleavedByLane(srcPtrTy.storageClass);
 	auto dstPtr = GetPointerToData(dstPtrId, 0, state);
 	auto srcPtr = GetPointerToData(srcPtrId, 0, state);

 	std::unordered_map<uint32_t, uint32_t> srcOffsets;

 	VisitMemoryObject(srcPtrId, [&](const MemoryElement &el) { srcOffsets[el.index] = el.offset; });

 	VisitMemoryObject(dstPtrId, [&](const MemoryElement &el) {
 		auto it = srcOffsets.find(el.index);
 		ASSERT(it != srcOffsets.end());
 		auto srcOffset = it->second;
 		auto dstOffset = el.offset;

 		auto dst = dstPtr + dstOffset;
 		auto src = srcPtr + srcOffset;
 		if(dstInterleavedByLane) { dst = InterleaveByLane(dst); }
 		if(srcInterleavedByLane) { src = InterleaveByLane(src); }

 		// TODO(b/131224163): Optimize based on src/dst storage classes.
 		auto robustness = OutOfBoundsBehavior::RobustBufferAccess;

 		auto value = src.Load<SIMD::Float>(robustness, state->activeLaneMask());
 		dst.Store(value, robustness, state->activeLaneMask());
 	});
 	return EmitResult::Continue;
 }

 SpirvShader::EmitResult SpirvShader::EmitMemoryBarrier(InsnIterator insn, EmitState *state) const
 {
 	auto semantics = spv::MemorySemanticsMask(GetConstScalarInt(insn.word(2)));
 	// TODO: We probably want to consider the memory scope here. For now,
 	// just always emit the full fence.
 	Fence(semantics);
 	return EmitResult::Continue;
 }

 void SpirvShader::VisitMemoryObjectInner(sw::SpirvShader::Type::ID id, sw::SpirvShader::Decorations d, uint32_t &index, uint32_t offset, const MemoryVisitor &f) const
 {
 	ApplyDecorationsForId(&d, id);
 	auto const &type = getType(id);

 	if(d.HasOffset)
 	{
 		offset += d.Offset;
 		d.HasOffset = false;
 	}

 	switch(type.opcode())
 	{
 		case spv::OpTypePointer:
 			VisitMemoryObjectInner(type.definition.word(3), d, index, offset, f);
 			break;
 		case spv::OpTypeInt:
 		case spv::OpTypeFloat:
 		case spv::OpTypeRuntimeArray:
 			f(MemoryElement{ index++, offset, type });
 			break;
 		case spv::OpTypeVector:
 		{
 			auto elemStride = (d.InsideMatrix && d.HasRowMajor && d.RowMajor) ? d.MatrixStride : static_cast<int32_t>(sizeof(float));
 			for(auto i = 0u; i < type.definition.word(3); i++)
 			{
 				VisitMemoryObjectInner(type.definition.word(2), d, index, offset + elemStride * i, f);
 			}
 			break;
 		}
 		case spv::OpTypeMatrix:
 		{
 			auto columnStride = (d.HasRowMajor && d.RowMajor) ? static_cast<int32_t>(sizeof(float)) : d.MatrixStride;
 			d.InsideMatrix = true;
 			for(auto i = 0u; i < type.definition.word(3); i++)
 			{
 				ASSERT(d.HasMatrixStride);
 				VisitMemoryObjectInner(type.definition.word(2), d, index, offset + columnStride * i, f);
 			}
 			break;
 		}
 		case spv::OpTypeStruct:
 			for(auto i = 0u; i < type.definition.wordCount() - 2; i++)
 			{
 				ApplyDecorationsForIdMember(&d, id, i);
 				VisitMemoryObjectInner(type.definition.word(i + 2), d, index, offset, f);
 			}
 			break;
 		case spv::OpTypeArray:
 		{
 			auto arraySize = GetConstScalarInt(type.definition.word(3));
 			for(auto i = 0u; i < arraySize; i++)
 			{
 				ASSERT(d.HasArrayStride);
 				VisitMemoryObjectInner(type.definition.word(2), d, index, offset + i * d.ArrayStride, f);
 			}
 			break;
 		}
 		default:
 			UNREACHABLE("%s", OpcodeName(type.opcode()).c_str());
 	}
 }

 void SpirvShader::VisitMemoryObject(sw::SpirvShader::Object::ID id, const MemoryVisitor &f) const
 {
 	auto typeId = getObject(id).type;
 	auto const &type = getType(typeId);
 	if(IsExplicitLayout(type.storageClass))
 	{
 		Decorations d{};
 		ApplyDecorationsForId(&d, id);
 		uint32_t index = 0;
 		VisitMemoryObjectInner(typeId, d, index, 0, f);
 	}
 	else
 	{
 		// Objects without explicit layout are tightly packed.
 		auto &elType = getType(type.element);
 		for(auto index = 0u; index < elType.sizeInComponents; index++)
 		{
 			auto offset = static_cast<uint32_t>(index * sizeof(float));
 			f({ index, offset, elType });
 		}
 	}
 }

 SIMD::Pointer SpirvShader::GetPointerToData(Object::ID id, int arrayIndex, EmitState const *state) const
 {
 	auto routine = state->routine;
 	auto &object = getObject(id);
 	switch(object.kind)
 	{
 		case Object::Kind::Pointer:
 		case Object::Kind::InterfaceVariable:
 			return state->getPointer(id);

 		case Object::Kind::DescriptorSet:
 		{
 			const auto &d = descriptorDecorations.at(id);
 			ASSERT(d.DescriptorSet >= 0 && d.DescriptorSet < vk::MAX_BOUND_DESCRIPTOR_SETS);
 			ASSERT(d.Binding >= 0);

 			auto set = state->getPointer(id);

 			auto setLayout = routine->pipelineLayout->getDescriptorSetLayout(d.DescriptorSet);
 			ASSERT_MSG(setLayout->hasBinding(d.Binding), "Descriptor set %d does not contain binding %d", int(d.DescriptorSet), int(d.Binding));
 			int bindingOffset = static_cast<int>(setLayout->getBindingOffset(d.Binding, arrayIndex));

 			Pointer<Byte> descriptor = set.base + bindingOffset;                                           // BufferDescriptor*
 			Pointer<Byte> data = *Pointer<Pointer<Byte>>(descriptor + OFFSET(vk::BufferDescriptor, ptr));  // void*
 			Int size = *Pointer<Int>(descriptor + OFFSET(vk::BufferDescriptor, sizeInBytes));
 			if(setLayout->isBindingDynamic(d.Binding))
 			{
 				uint32_t dynamicBindingIndex =
 				    routine->pipelineLayout->getDynamicOffsetBase(d.DescriptorSet) +
 				    setLayout->getDynamicDescriptorOffset(d.Binding) +
 				    arrayIndex;
 				Int offset = routine->descriptorDynamicOffsets[dynamicBindingIndex];
 				Int robustnessSize = *Pointer<Int>(descriptor + OFFSET(vk::BufferDescriptor, robustnessSize));
 				return SIMD::Pointer(data + offset, Min(size, robustnessSize - offset));
 			}
 			else
 			{
 				return SIMD::Pointer(data, size);
 			}
 		}

 		default:
 			UNREACHABLE("Invalid pointer kind %d", int(object.kind));
 			return SIMD::Pointer(Pointer<Byte>(), 0);
 	}
 }

 std::memory_order SpirvShader::MemoryOrder(spv::MemorySemanticsMask memorySemantics)
 {
 	auto control = static_cast<uint32_t>(memorySemantics) & static_cast<uint32_t>(
 	                                                            spv::MemorySemanticsAcquireMask |
 	                                                            spv::MemorySemanticsReleaseMask |
 	                                                            spv::MemorySemanticsAcquireReleaseMask |
 	                                                            spv::MemorySemanticsSequentiallyConsistentMask);
 	switch(control)
 	{
 		case spv::MemorySemanticsMaskNone: return std::memory_order_relaxed;
 		case spv::MemorySemanticsAcquireMask: return std::memory_order_acquire;
 		case spv::MemorySemanticsReleaseMask: return std::memory_order_release;
 		case spv::MemorySemanticsAcquireReleaseMask: return std::memory_order_acq_rel;
 		case spv::MemorySemanticsSequentiallyConsistentMask: return std::memory_order_acq_rel;  // Vulkan 1.1: "SequentiallyConsistent is treated as AcquireRelease"
 		default:
 			// "it is invalid for more than one of these four bits to be set:
 			// Acquire, Release, AcquireRelease, or SequentiallyConsistent."
 			UNREACHABLE("MemorySemanticsMask: %x", int(control));
 			return std::memory_order_acq_rel;
 	}
 }

 bool SpirvShader::StoresInHelperInvocation(spv::StorageClass storageClass)
 {
 	switch(storageClass)
 	{
 		case spv::StorageClassUniform:
 		case spv::StorageClassStorageBuffer:
 		case spv::StorageClassImage:
 			return false;
 		default:
 			return true;
 	}
 }

 bool SpirvShader::IsExplicitLayout(spv::StorageClass storageClass)
 {
 	switch(storageClass)
 	{
 		case spv::StorageClassUniform:
 		case spv::StorageClassStorageBuffer:
 		case spv::StorageClassPushConstant:
 			return true;
 		default:
 			return false;
 	}
 }

 sw::SIMD::Pointer SpirvShader::InterleaveByLane(sw::SIMD::Pointer p)
 {
 	p *= sw::SIMD::Width;
 	p.staticOffsets[0] += 0 * sizeof(float);
 	p.staticOffsets[1] += 1 * sizeof(float);
 	p.staticOffsets[2] += 2 * sizeof(float);
 	p.staticOffsets[3] += 3 * sizeof(float);
 	return p;
 }

 bool SpirvShader::IsStorageInterleavedByLane(spv::StorageClass storageClass)
 {
 	switch(storageClass)
 	{
 		case spv::StorageClassUniform:
 		case spv::StorageClassStorageBuffer:
 		case spv::StorageClassPushConstant:
 		case spv::StorageClassWorkgroup:
 		case spv::StorageClassImage:
 			return false;
 		default:
 			return true;
 	}
 }

 }  // namespace sw
	// Copyright 2019 The SwiftShader Authors. All Rights Reserved.
	//
	// Licensed under the Apache License, Version 2.0 (the "License");
	// you may not use this file except in compliance with the License.
	// You may obtain a copy of the License at
	//
	// http://www.apache.org/licenses/LICENSE-2.0
	//
	// Unless required by applicable law or agreed to in writing, software
	// distributed under the License is distributed on an "AS IS" BASIS,
	// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	// See the License for the specific language governing permissions and
	// limitations under the License.

	#include "SpirvShader.hpp"

	#include "ShaderCore.hpp"

	#include "Vulkan/VkPipelineLayout.hpp"

	#include <spirv/unified1/spirv.hpp>

	namespace sw {

	SpirvShader::EmitResult SpirvShader::EmitLoad(InsnIterator insn, EmitState *state) const
	{
	bool atomic = (insn.opcode() == spv::OpAtomicLoad);
	Object::ID resultId = insn.word(2);
	Object::ID pointerId = insn.word(3);
	auto &result = getObject(resultId);
	auto &resultTy = getType(result.type);
	auto &pointer = getObject(pointerId);
	auto &pointerTy = getType(pointer.type);
	std::memory_order memoryOrder = std::memory_order_relaxed;

	ASSERT(getType(pointer.type).element == result.type);
	ASSERT(Type::ID(insn.word(1)) == result.type);
	ASSERT(!atomic \|\| getType(getType(pointer.type).element).opcode() == spv::OpTypeInt); // Vulkan 1.1: "Atomic instructions must declare a scalar 32-bit integer type, for the value pointed to by Pointer."

	if(pointerTy.storageClass == spv::StorageClassUniformConstant)
	{
	// Just propagate the pointer.
	auto &ptr = state->getPointer(pointerId);
	state->createPointer(resultId, ptr);
	return EmitResult::Continue;
	}

	if(atomic)
	{
	Object::ID semanticsId = insn.word(5);
	auto memorySemantics = static_cast<spv::MemorySemanticsMask>(getObject(semanticsId).constantValue[0]);
	memoryOrder = MemoryOrder(memorySemantics);
	}

	auto ptr = GetPointerToData(pointerId, 0, state);
	bool interleavedByLane = IsStorageInterleavedByLane(pointerTy.storageClass);
	auto &dst = state->createIntermediate(resultId, resultTy.sizeInComponents);
	auto robustness = state->getOutOfBoundsBehavior(pointerTy.storageClass);

	VisitMemoryObject(pointerId, [&](const MemoryElement &el) {
	auto p = ptr + el.offset;
	if(interleavedByLane) { p = InterleaveByLane(p); } // TODO: Interleave once, then add offset?
	dst.move(el.index, p.Load<SIMD::Float>(robustness, state->activeLaneMask(), atomic, memoryOrder));
	});

	return EmitResult::Continue;
	}

	SpirvShader::EmitResult SpirvShader::EmitStore(InsnIterator insn, EmitState *state) const
	{
	bool atomic = (insn.opcode() == spv::OpAtomicStore);
	Object::ID pointerId = insn.word(1);
	Object::ID objectId = insn.word(atomic ? 4 : 2);
	auto &object = getObject(objectId);
	auto &pointer = getObject(pointerId);
	auto &pointerTy = getType(pointer.type);
	auto &elementTy = getType(pointerTy.element);
	std::memory_order memoryOrder = std::memory_order_relaxed;

	if(atomic)
	{
	Object::ID semanticsId = insn.word(3);
	auto memorySemantics = static_cast<spv::MemorySemanticsMask>(getObject(semanticsId).constantValue[0]);
	memoryOrder = MemoryOrder(memorySemantics);
	}

	ASSERT(!atomic \|\| elementTy.opcode() == spv::OpTypeInt); // Vulkan 1.1: "Atomic instructions must declare a scalar 32-bit integer type, for the value pointed to by Pointer."

	auto ptr = GetPointerToData(pointerId, 0, state);
	bool interleavedByLane = IsStorageInterleavedByLane(pointerTy.storageClass);
	auto robustness = state->getOutOfBoundsBehavior(pointerTy.storageClass);

	SIMD::Int mask = state->activeLaneMask();
	if(!StoresInHelperInvocation(pointerTy.storageClass))
	{
	mask = mask & state->storesAndAtomicsMask();
	}

	if(object.kind == Object::Kind::Constant)
	{
	// Constant source data.
	const uint32_t *src = object.constantValue.get();
	VisitMemoryObject(pointerId, [&](const MemoryElement &el) {
	auto p = ptr + el.offset;
	if(interleavedByLane) { p = InterleaveByLane(p); }
	p.Store(SIMD::Int(src[el.index]), robustness, mask, atomic, memoryOrder);
	});
	}
	else
	{
	// Intermediate source data.
	auto &src = state->getIntermediate(objectId);
	VisitMemoryObject(pointerId, [&](const MemoryElement &el) {
	auto p = ptr + el.offset;
	if(interleavedByLane) { p = InterleaveByLane(p); }
	p.Store(src.Float(el.index), robustness, mask, atomic, memoryOrder);
	});
	}

	return EmitResult::Continue;
	}

	SpirvShader::EmitResult SpirvShader::EmitVariable(InsnIterator insn, EmitState *state) const
	{
	auto routine = state->routine;
	Object::ID resultId = insn.word(2);
	auto &object = getObject(resultId);
	auto &objectTy = getType(object.type);

	switch(objectTy.storageClass)
	{
	case spv::StorageClassOutput:
	case spv::StorageClassPrivate:
	case spv::StorageClassFunction:
	{
	ASSERT(objectTy.opcode() == spv::OpTypePointer);
	auto base = &routine->getVariable(resultId)[0];
	auto elementTy = getType(objectTy.element);
	auto size = elementTy.sizeInComponents * static_cast<uint32_t>(sizeof(float)) * SIMD::Width;
	state->createPointer(resultId, SIMD::Pointer(base, size));
	break;
	}
	case spv::StorageClassWorkgroup:
	{
	ASSERT(objectTy.opcode() == spv::OpTypePointer);
	auto base = &routine->workgroupMemory[0];
	auto size = workgroupMemory.size();
	state->createPointer(resultId, SIMD::Pointer(base, size, workgroupMemory.offsetOf(resultId)));
	break;
	}
	case spv::StorageClassInput:
	{
	if(object.kind == Object::Kind::InterfaceVariable)
	{
	auto &dst = routine->getVariable(resultId);
	int offset = 0;
	VisitInterface(resultId,
	[&](Decorations const &d, AttribType type) {
	auto scalarSlot = d.Location << 2 \| d.Component;
	dst[offset++] = routine->inputs[scalarSlot];
	});
	}
	ASSERT(objectTy.opcode() == spv::OpTypePointer);
	auto base = &routine->getVariable(resultId)[0];
	auto elementTy = getType(objectTy.element);
	auto size = elementTy.sizeInComponents * static_cast<uint32_t>(sizeof(float)) * SIMD::Width;
	state->createPointer(resultId, SIMD::Pointer(base, size));
	break;
	}
	case spv::StorageClassUniformConstant:
	{
	const auto &d = descriptorDecorations.at(resultId);
	ASSERT(d.DescriptorSet >= 0);
	ASSERT(d.Binding >= 0);

	uint32_t arrayIndex = 0; // TODO(b/129523279)
	auto setLayout = routine->pipelineLayout->getDescriptorSetLayout(d.DescriptorSet);
	if(setLayout->hasBinding(d.Binding))
	{
	uint32_t bindingOffset = static_cast<uint32_t>(setLayout->getBindingOffset(d.Binding, arrayIndex));
	Pointer<Byte> set = routine->descriptorSets[d.DescriptorSet]; // DescriptorSet*
	Pointer<Byte> binding = Pointer<Byte>(set + bindingOffset); // vk::SampledImageDescriptor*
	auto size = 0; // Not required as this pointer is not directly used by SIMD::Read or SIMD::Write.
	state->createPointer(resultId, SIMD::Pointer(binding, size));
	}
	else
	{
	// TODO: Error if the variable with the non-existant binding is
	// used? Or perhaps strip these unused variable declarations as
	// a preprocess on the SPIR-V?
	}
	break;
	}
	case spv::StorageClassUniform:
	case spv::StorageClassStorageBuffer:
	{
	const auto &d = descriptorDecorations.at(resultId);
	ASSERT(d.DescriptorSet >= 0);
	auto size = 0; // Not required as this pointer is not directly used by SIMD::Read or SIMD::Write.
	// Note: the module may contain descriptor set references that are not suitable for this implementation -- using a set index higher than the number
	// of descriptor set binding points we support. As long as the selected entrypoint doesn't actually touch the out of range binding points, this
	// is valid. In this case make the value nullptr to make it easier to diagnose an attempt to dereference it.
	if(d.DescriptorSet < vk::MAX_BOUND_DESCRIPTOR_SETS)
	{
	state->createPointer(resultId, SIMD::Pointer(routine->descriptorSets[d.DescriptorSet], size));
	}
	else
	{
	state->createPointer(resultId, SIMD::Pointer(nullptr, 0));
	}
	break;
	}
	case spv::StorageClassPushConstant:
	{
	state->createPointer(resultId, SIMD::Pointer(routine->pushConstants, vk::MAX_PUSH_CONSTANT_SIZE));
	break;
	}
	default:
	UNREACHABLE("Storage class %d", objectTy.storageClass);
	break;
	}

	if(insn.wordCount() > 4)
	{
	Object::ID initializerId = insn.word(4);
	if(getObject(initializerId).kind != Object::Kind::Constant)
	{
	UNIMPLEMENTED("Non-constant initializers not yet implemented");
	}
	switch(objectTy.storageClass)
	{
	case spv::StorageClassOutput:
	case spv::StorageClassPrivate:
	case spv::StorageClassFunction:
	{
	bool interleavedByLane = IsStorageInterleavedByLane(objectTy.storageClass);
	auto ptr = GetPointerToData(resultId, 0, state);
	GenericValue initialValue(this, state, initializerId);
	VisitMemoryObject(resultId, [&](const MemoryElement &el) {
	auto p = ptr + el.offset;
	if(interleavedByLane) { p = InterleaveByLane(p); }
	auto robustness = OutOfBoundsBehavior::UndefinedBehavior; // Local variables are always within bounds.
	p.Store(initialValue.Float(el.index), robustness, state->activeLaneMask());
	});
	break;
	}
	default:
	ASSERT_MSG(initializerId == 0, "Vulkan does not permit variables of storage class %d to have initializers", int(objectTy.storageClass));
	}
	}

	return EmitResult::Continue;
	}

	SpirvShader::EmitResult SpirvShader::EmitCopyMemory(InsnIterator insn, EmitState *state) const
	{
	Object::ID dstPtrId = insn.word(1);
	Object::ID srcPtrId = insn.word(2);
	auto &dstPtrTy = getType(getObject(dstPtrId).type);
	auto &srcPtrTy = getType(getObject(srcPtrId).type);
	ASSERT(dstPtrTy.element == srcPtrTy.element);

	bool dstInterleavedByLane = IsStorageInterleavedByLane(dstPtrTy.storageClass);
	bool srcInterleavedByLane = IsStorageInterleavedByLane(srcPtrTy.storageClass);
	auto dstPtr = GetPointerToData(dstPtrId, 0, state);
	auto srcPtr = GetPointerToData(srcPtrId, 0, state);

	std::unordered_map<uint32_t, uint32_t> srcOffsets;

	VisitMemoryObject(srcPtrId, [&](const MemoryElement &el) { srcOffsets[el.index] = el.offset; });

	VisitMemoryObject(dstPtrId, [&](const MemoryElement &el) {
	auto it = srcOffsets.find(el.index);
	ASSERT(it != srcOffsets.end());
	auto srcOffset = it->second;
	auto dstOffset = el.offset;

	auto dst = dstPtr + dstOffset;
	auto src = srcPtr + srcOffset;
	if(dstInterleavedByLane) { dst = InterleaveByLane(dst); }
	if(srcInterleavedByLane) { src = InterleaveByLane(src); }

	// TODO(b/131224163): Optimize based on src/dst storage classes.
	auto robustness = OutOfBoundsBehavior::RobustBufferAccess;

	auto value = src.Load<SIMD::Float>(robustness, state->activeLaneMask());
	dst.Store(value, robustness, state->activeLaneMask());
	});
	return EmitResult::Continue;
	}

	SpirvShader::EmitResult SpirvShader::EmitMemoryBarrier(InsnIterator insn, EmitState *state) const
	{
	auto semantics = spv::MemorySemanticsMask(GetConstScalarInt(insn.word(2)));
	// TODO: We probably want to consider the memory scope here. For now,
	// just always emit the full fence.
	Fence(semantics);
	return EmitResult::Continue;
	}

	void SpirvShader::VisitMemoryObjectInner(sw::SpirvShader::Type::ID id, sw::SpirvShader::Decorations d, uint32_t &index, uint32_t offset, const MemoryVisitor &f) const
	{
	ApplyDecorationsForId(&d, id);
	auto const &type = getType(id);

	if(d.HasOffset)
	{
	offset += d.Offset;
	d.HasOffset = false;
	}

	switch(type.opcode())
	{
	case spv::OpTypePointer:
	VisitMemoryObjectInner(type.definition.word(3), d, index, offset, f);
	break;
	case spv::OpTypeInt:
	case spv::OpTypeFloat:
	case spv::OpTypeRuntimeArray:
	f(MemoryElement{ index++, offset, type });
	break;
	case spv::OpTypeVector:
	{
	auto elemStride = (d.InsideMatrix && d.HasRowMajor && d.RowMajor) ? d.MatrixStride : static_cast<int32_t>(sizeof(float));
	for(auto i = 0u; i < type.definition.word(3); i++)
	{
	VisitMemoryObjectInner(type.definition.word(2), d, index, offset + elemStride * i, f);
	}
	break;
	}
	case spv::OpTypeMatrix:
	{
	auto columnStride = (d.HasRowMajor && d.RowMajor) ? static_cast<int32_t>(sizeof(float)) : d.MatrixStride;
	d.InsideMatrix = true;
	for(auto i = 0u; i < type.definition.word(3); i++)
	{
	ASSERT(d.HasMatrixStride);
	VisitMemoryObjectInner(type.definition.word(2), d, index, offset + columnStride * i, f);
	}
	break;
	}
	case spv::OpTypeStruct:
	for(auto i = 0u; i < type.definition.wordCount() - 2; i++)
	{
	ApplyDecorationsForIdMember(&d, id, i);
	VisitMemoryObjectInner(type.definition.word(i + 2), d, index, offset, f);
	}
	break;
	case spv::OpTypeArray:
	{
	auto arraySize = GetConstScalarInt(type.definition.word(3));
	for(auto i = 0u; i < arraySize; i++)
	{
	ASSERT(d.HasArrayStride);
	VisitMemoryObjectInner(type.definition.word(2), d, index, offset + i * d.ArrayStride, f);
	}
	break;
	}
	default:
	UNREACHABLE("%s", OpcodeName(type.opcode()).c_str());
	}
	}

	void SpirvShader::VisitMemoryObject(sw::SpirvShader::Object::ID id, const MemoryVisitor &f) const
	{
	auto typeId = getObject(id).type;
	auto const &type = getType(typeId);
	if(IsExplicitLayout(type.storageClass))
	{
	Decorations d{};
	ApplyDecorationsForId(&d, id);
	uint32_t index = 0;
	VisitMemoryObjectInner(typeId, d, index, 0, f);
	}
	else
	{
	// Objects without explicit layout are tightly packed.
	auto &elType = getType(type.element);
	for(auto index = 0u; index < elType.sizeInComponents; index++)
	{
	auto offset = static_cast<uint32_t>(index * sizeof(float));
	f({ index, offset, elType });
	}
	}
	}

	SIMD::Pointer SpirvShader::GetPointerToData(Object::ID id, int arrayIndex, EmitState const *state) const
	{
	auto routine = state->routine;
	auto &object = getObject(id);
	switch(object.kind)
	{
	case Object::Kind::Pointer:
	case Object::Kind::InterfaceVariable:
	return state->getPointer(id);

	case Object::Kind::DescriptorSet:
	{
	const auto &d = descriptorDecorations.at(id);
	ASSERT(d.DescriptorSet >= 0 && d.DescriptorSet < vk::MAX_BOUND_DESCRIPTOR_SETS);
	ASSERT(d.Binding >= 0);

	auto set = state->getPointer(id);

	auto setLayout = routine->pipelineLayout->getDescriptorSetLayout(d.DescriptorSet);
	ASSERT_MSG(setLayout->hasBinding(d.Binding), "Descriptor set %d does not contain binding %d", int(d.DescriptorSet), int(d.Binding));
	int bindingOffset = static_cast<int>(setLayout->getBindingOffset(d.Binding, arrayIndex));

	Pointer<Byte> descriptor = set.base + bindingOffset; // BufferDescriptor*
	Pointer<Byte> data = Pointer<Pointer<Byte>>(descriptor + OFFSET(vk::BufferDescriptor, ptr)); // void
	Int size = *Pointer<Int>(descriptor + OFFSET(vk::BufferDescriptor, sizeInBytes));
	if(setLayout->isBindingDynamic(d.Binding))
	{
	uint32_t dynamicBindingIndex =
	routine->pipelineLayout->getDynamicOffsetBase(d.DescriptorSet) +
	setLayout->getDynamicDescriptorOffset(d.Binding) +
	arrayIndex;
	Int offset = routine->descriptorDynamicOffsets[dynamicBindingIndex];
	Int robustnessSize = *Pointer<Int>(descriptor + OFFSET(vk::BufferDescriptor, robustnessSize));
	return SIMD::Pointer(data + offset, Min(size, robustnessSize - offset));
	}
	else
	{
	return SIMD::Pointer(data, size);
	}
	}

	default:
	UNREACHABLE("Invalid pointer kind %d", int(object.kind));
	return SIMD::Pointer(Pointer<Byte>(), 0);
	}
	}

	std::memory_order SpirvShader::MemoryOrder(spv::MemorySemanticsMask memorySemantics)
	{
	auto control = static_cast<uint32_t>(memorySemantics) & static_cast<uint32_t>(
	spv::MemorySemanticsAcquireMask \|
	spv::MemorySemanticsReleaseMask \|
	spv::MemorySemanticsAcquireReleaseMask \|
	spv::MemorySemanticsSequentiallyConsistentMask);
	switch(control)
	{
	case spv::MemorySemanticsMaskNone: return std::memory_order_relaxed;
	case spv::MemorySemanticsAcquireMask: return std::memory_order_acquire;
	case spv::MemorySemanticsReleaseMask: return std::memory_order_release;
	case spv::MemorySemanticsAcquireReleaseMask: return std::memory_order_acq_rel;
	case spv::MemorySemanticsSequentiallyConsistentMask: return std::memory_order_acq_rel; // Vulkan 1.1: "SequentiallyConsistent is treated as AcquireRelease"
	default:
	// "it is invalid for more than one of these four bits to be set:
	// Acquire, Release, AcquireRelease, or SequentiallyConsistent."
	UNREACHABLE("MemorySemanticsMask: %x", int(control));
	return std::memory_order_acq_rel;
	}
	}

	bool SpirvShader::StoresInHelperInvocation(spv::StorageClass storageClass)
	{
	switch(storageClass)
	{
	case spv::StorageClassUniform:
	case spv::StorageClassStorageBuffer:
	case spv::StorageClassImage:
	return false;
	default:
	return true;
	}
	}

	bool SpirvShader::IsExplicitLayout(spv::StorageClass storageClass)
	{
	switch(storageClass)
	{
	case spv::StorageClassUniform:
	case spv::StorageClassStorageBuffer:
	case spv::StorageClassPushConstant:
	return true;
	default:
	return false;
	}
	}

	sw::SIMD::Pointer SpirvShader::InterleaveByLane(sw::SIMD::Pointer p)
	{
	p *= sw::SIMD::Width;
	p.staticOffsets[0] += 0 * sizeof(float);
	p.staticOffsets[1] += 1 * sizeof(float);
	p.staticOffsets[2] += 2 * sizeof(float);
	p.staticOffsets[3] += 3 * sizeof(float);
	return p;
	}

	bool SpirvShader::IsStorageInterleavedByLane(spv::StorageClass storageClass)
	{
	switch(storageClass)
	{
	case spv::StorageClassUniform:
	case spv::StorageClassStorageBuffer:
	case spv::StorageClassPushConstant:
	case spv::StorageClassWorkgroup:
	case spv::StorageClassImage:
	return false;
	default:
	return true;
	}
	}

	} // namespace sw