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// Copyright (c) 2022 Google LLC
// 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
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// See the License for the specific language governing permissions and
// limitations under the License.
#include "source/opt/pass.h"
namespace spvtools {
namespace opt {
// See optimizer.hpp for documentation.
class SpreadVolatileSemantics : public Pass {
SpreadVolatileSemantics() {}
const char* name() const override { return "spread-volatile-semantics"; }
Status Process() override;
IRContext::Analysis GetPreservedAnalyses() override {
return IRContext::kAnalysisDefUse | IRContext::kAnalysisDecorations |
// Returns true if it does not have an execution model. Linkage shaders do not
// have an execution model.
bool HasNoExecutionModel() {
return get_module()->entry_points().empty() &&
// Iterates interface variables and spreads the Volatile semantics if it has
// load instructions for the Volatile semantics.
Pass::Status SpreadVolatileSemanticsToVariables(
const bool is_vk_memory_model_enabled);
// Returns whether |var_id| is the result id of a target builtin variable for
// the volatile semantics for |execution_model| based on the Vulkan spec
// VUID-StandaloneSpirv-VulkanMemoryModel-04678 or
// VUID-StandaloneSpirv-VulkanMemoryModel-04679.
bool IsTargetForVolatileSemantics(uint32_t var_id,
SpvExecutionModel execution_model);
// Collects interface variables that need the volatile semantics.
// |is_vk_memory_model_enabled| is true if VulkanMemoryModel capability is
// enabled.
void CollectTargetsForVolatileSemantics(
const bool is_vk_memory_model_enabled);
// Reports an error if an interface variable is used by two entry points and
// it needs the Volatile decoration for one but not for another. Returns true
// if the error must be reported.
bool HasInterfaceInConflictOfVolatileSemantics();
// Returns whether the variable whose result is |var_id| is used by a
// non-volatile load or a pointer to it is used by a non-volatile load in
// |entry_point| or not.
bool IsTargetUsedByNonVolatileLoadInEntryPoint(uint32_t var_id,
Instruction* entry_point);
// Visits load instructions of pointers to variable whose result id is
// |var_id| if the load instructions are in reachable functions from entry
// points. |handle_load| is a function to do some actions for the load
// instructions. Finishes the traversal and returns false if |handle_load|
// returns false for a load instruction. Otherwise, returns true after running
// |handle_load| for all the load instructions.
bool VisitLoadsOfPointersToVariableInEntries(
uint32_t var_id, const std::function<bool(Instruction*)>& handle_load,
const std::unordered_set<uint32_t>& function_ids);
// Sets Memory Operands of OpLoad instructions that load |var| or pointers
// of |var| as Volatile if the function id of the OpLoad instruction is
// included in |entry_function_ids|.
void SetVolatileForLoadsInEntries(
Instruction* var, const std::unordered_set<uint32_t>& entry_function_ids);
// Adds OpDecorate Volatile for |var| if it does not exist.
void DecorateVarWithVolatile(Instruction* var);
// Returns a set of entry function ids to spread the volatile semantics for
// the variable with the result id |var_id|.
std::unordered_set<uint32_t> EntryFunctionsToSpreadVolatileSemanticsForVar(
uint32_t var_id) {
auto itr = var_ids_to_entry_fn_for_volatile_semantics_.find(var_id);
if (itr == var_ids_to_entry_fn_for_volatile_semantics_.end()) return {};
return itr->second;
// Specifies that we have to spread the volatile semantics for the
// variable with the result id |var_id| for the entry point |entry_point|.
void MarkVolatileSemanticsForVariable(uint32_t var_id,
Instruction* entry_point);
// Result ids of variables to entry function ids for the volatile semantics
// spread.
std::unordered_map<uint32_t, std::unordered_set<uint32_t>>
} // namespace opt
} // namespace spvtools