SPIRV-Tools/source/opt/spread_volatile_semantics.cpp

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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
//
// 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 "source/opt/spread_volatile_semantics.h"
#include "source/opt/decoration_manager.h"
#include "source/spirv_constant.h"
namespace spvtools {
namespace opt {
namespace {
constexpr uint32_t kOpDecorateInOperandBuiltinDecoration = 2u;
constexpr uint32_t kOpLoadInOperandMemoryOperands = 1u;
constexpr uint32_t kOpEntryPointInOperandEntryPoint = 1u;
constexpr uint32_t kOpEntryPointInOperandInterface = 3u;
bool HasBuiltinDecoration(analysis::DecorationManager* decoration_manager,
uint32_t var_id, uint32_t built_in) {
return decoration_manager->FindDecoration(
var_id, uint32_t(spv::Decoration::BuiltIn),
[built_in](const Instruction& inst) {
return built_in == inst.GetSingleWordInOperand(
kOpDecorateInOperandBuiltinDecoration);
});
}
bool IsBuiltInForRayTracingVolatileSemantics(spv::BuiltIn built_in) {
switch (built_in) {
case spv::BuiltIn::SMIDNV:
case spv::BuiltIn::WarpIDNV:
case spv::BuiltIn::SubgroupSize:
case spv::BuiltIn::SubgroupLocalInvocationId:
case spv::BuiltIn::SubgroupEqMask:
case spv::BuiltIn::SubgroupGeMask:
case spv::BuiltIn::SubgroupGtMask:
case spv::BuiltIn::SubgroupLeMask:
case spv::BuiltIn::SubgroupLtMask:
return true;
default:
return false;
}
}
bool HasBuiltinForRayTracingVolatileSemantics(
analysis::DecorationManager* decoration_manager, uint32_t var_id) {
return decoration_manager->FindDecoration(
var_id, uint32_t(spv::Decoration::BuiltIn), [](const Instruction& inst) {
spv::BuiltIn built_in = spv::BuiltIn(
inst.GetSingleWordInOperand(kOpDecorateInOperandBuiltinDecoration));
return IsBuiltInForRayTracingVolatileSemantics(built_in);
});
}
bool HasVolatileDecoration(analysis::DecorationManager* decoration_manager,
uint32_t var_id) {
return decoration_manager->HasDecoration(var_id,
uint32_t(spv::Decoration::Volatile));
}
} // namespace
Pass::Status SpreadVolatileSemantics::Process() {
if (HasNoExecutionModel()) {
return Status::SuccessWithoutChange;
}
const bool is_vk_memory_model_enabled =
context()->get_feature_mgr()->HasCapability(
spv::Capability::VulkanMemoryModel);
CollectTargetsForVolatileSemantics(is_vk_memory_model_enabled);
// If VulkanMemoryModel capability is not enabled, we have to set Volatile
// decoration for interface variables instead of setting Volatile for load
// instructions. If an interface (or pointers to it) is used by two load
// instructions in two entry points and one must be volatile while another
// is not, we have to report an error for the conflict.
if (!is_vk_memory_model_enabled &&
HasInterfaceInConflictOfVolatileSemantics()) {
return Status::Failure;
}
return SpreadVolatileSemanticsToVariables(is_vk_memory_model_enabled);
}
Pass::Status SpreadVolatileSemantics::SpreadVolatileSemanticsToVariables(
const bool is_vk_memory_model_enabled) {
Status status = Status::SuccessWithoutChange;
for (Instruction& var : context()->types_values()) {
auto entry_function_ids =
EntryFunctionsToSpreadVolatileSemanticsForVar(var.result_id());
if (entry_function_ids.empty()) {
continue;
}
if (is_vk_memory_model_enabled) {
SetVolatileForLoadsInEntries(&var, entry_function_ids);
} else {
DecorateVarWithVolatile(&var);
}
status = Status::SuccessWithChange;
}
return status;
}
bool SpreadVolatileSemantics::IsTargetUsedByNonVolatileLoadInEntryPoint(
uint32_t var_id, Instruction* entry_point) {
uint32_t entry_function_id =
entry_point->GetSingleWordInOperand(kOpEntryPointInOperandEntryPoint);
std::unordered_set<uint32_t> funcs;
context()->CollectCallTreeFromRoots(entry_function_id, &funcs);
return !VisitLoadsOfPointersToVariableInEntries(
var_id,
[](Instruction* load) {
// If it has a load without volatile memory operand, finish traversal
// and return false.
if (load->NumInOperands() <= kOpLoadInOperandMemoryOperands) {
return false;
}
uint32_t memory_operands =
load->GetSingleWordInOperand(kOpLoadInOperandMemoryOperands);
return (memory_operands & uint32_t(spv::MemoryAccessMask::Volatile)) !=
0;
},
funcs);
}
bool SpreadVolatileSemantics::HasInterfaceInConflictOfVolatileSemantics() {
for (Instruction& entry_point : get_module()->entry_points()) {
spv::ExecutionModel execution_model =
static_cast<spv::ExecutionModel>(entry_point.GetSingleWordInOperand(0));
for (uint32_t operand_index = kOpEntryPointInOperandInterface;
operand_index < entry_point.NumInOperands(); ++operand_index) {
uint32_t var_id = entry_point.GetSingleWordInOperand(operand_index);
if (!EntryFunctionsToSpreadVolatileSemanticsForVar(var_id).empty() &&
!IsTargetForVolatileSemantics(var_id, execution_model) &&
IsTargetUsedByNonVolatileLoadInEntryPoint(var_id, &entry_point)) {
Instruction* inst = context()->get_def_use_mgr()->GetDef(var_id);
context()->EmitErrorMessage(
"Variable is a target for Volatile semantics for an entry point, "
"but it is not for another entry point",
inst);
return true;
}
}
}
return false;
}
void SpreadVolatileSemantics::MarkVolatileSemanticsForVariable(
uint32_t var_id, Instruction* entry_point) {
uint32_t entry_function_id =
entry_point->GetSingleWordInOperand(kOpEntryPointInOperandEntryPoint);
auto itr = var_ids_to_entry_fn_for_volatile_semantics_.find(var_id);
if (itr == var_ids_to_entry_fn_for_volatile_semantics_.end()) {
var_ids_to_entry_fn_for_volatile_semantics_[var_id] = {entry_function_id};
return;
}
itr->second.insert(entry_function_id);
}
void SpreadVolatileSemantics::CollectTargetsForVolatileSemantics(
const bool is_vk_memory_model_enabled) {
for (Instruction& entry_point : get_module()->entry_points()) {
spv::ExecutionModel execution_model =
static_cast<spv::ExecutionModel>(entry_point.GetSingleWordInOperand(0));
for (uint32_t operand_index = kOpEntryPointInOperandInterface;
operand_index < entry_point.NumInOperands(); ++operand_index) {
uint32_t var_id = entry_point.GetSingleWordInOperand(operand_index);
if (!IsTargetForVolatileSemantics(var_id, execution_model)) {
continue;
}
if (is_vk_memory_model_enabled ||
IsTargetUsedByNonVolatileLoadInEntryPoint(var_id, &entry_point)) {
MarkVolatileSemanticsForVariable(var_id, &entry_point);
}
}
}
}
void SpreadVolatileSemantics::DecorateVarWithVolatile(Instruction* var) {
analysis::DecorationManager* decoration_manager =
context()->get_decoration_mgr();
uint32_t var_id = var->result_id();
if (HasVolatileDecoration(decoration_manager, var_id)) {
return;
}
get_decoration_mgr()->AddDecoration(
spv::Op::OpDecorate,
{{spv_operand_type_t::SPV_OPERAND_TYPE_ID, {var_id}},
{spv_operand_type_t::SPV_OPERAND_TYPE_LITERAL_INTEGER,
{uint32_t(spv::Decoration::Volatile)}}});
}
bool SpreadVolatileSemantics::VisitLoadsOfPointersToVariableInEntries(
uint32_t var_id, const std::function<bool(Instruction*)>& handle_load,
const std::unordered_set<uint32_t>& function_ids) {
std::vector<uint32_t> worklist({var_id});
auto* def_use_mgr = context()->get_def_use_mgr();
while (!worklist.empty()) {
uint32_t ptr_id = worklist.back();
worklist.pop_back();
bool finish_traversal = !def_use_mgr->WhileEachUser(
ptr_id, [this, &worklist, &ptr_id, handle_load,
&function_ids](Instruction* user) {
BasicBlock* block = context()->get_instr_block(user);
if (block == nullptr ||
function_ids.find(block->GetParent()->result_id()) ==
function_ids.end()) {
return true;
}
if (user->opcode() == spv::Op::OpAccessChain ||
user->opcode() == spv::Op::OpInBoundsAccessChain ||
user->opcode() == spv::Op::OpPtrAccessChain ||
user->opcode() == spv::Op::OpInBoundsPtrAccessChain ||
user->opcode() == spv::Op::OpCopyObject) {
if (ptr_id == user->GetSingleWordInOperand(0))
worklist.push_back(user->result_id());
return true;
}
if (user->opcode() != spv::Op::OpLoad) {
return true;
}
return handle_load(user);
});
if (finish_traversal) return false;
}
return true;
}
void SpreadVolatileSemantics::SetVolatileForLoadsInEntries(
Instruction* var, const std::unordered_set<uint32_t>& entry_function_ids) {
// Set Volatile memory operand for all load instructions if they do not have
// it.
for (auto entry_id : entry_function_ids) {
std::unordered_set<uint32_t> funcs;
context()->CollectCallTreeFromRoots(entry_id, &funcs);
VisitLoadsOfPointersToVariableInEntries(
var->result_id(),
[](Instruction* load) {
if (load->NumInOperands() <= kOpLoadInOperandMemoryOperands) {
load->AddOperand({SPV_OPERAND_TYPE_MEMORY_ACCESS,
{uint32_t(spv::MemoryAccessMask::Volatile)}});
return true;
}
uint32_t memory_operands =
load->GetSingleWordInOperand(kOpLoadInOperandMemoryOperands);
memory_operands |= uint32_t(spv::MemoryAccessMask::Volatile);
load->SetInOperand(kOpLoadInOperandMemoryOperands, {memory_operands});
return true;
},
funcs);
}
}
bool SpreadVolatileSemantics::IsTargetForVolatileSemantics(
uint32_t var_id, spv::ExecutionModel execution_model) {
analysis::DecorationManager* decoration_manager =
context()->get_decoration_mgr();
if (execution_model == spv::ExecutionModel::Fragment) {
return get_module()->version() >= SPV_SPIRV_VERSION_WORD(1, 6) &&
HasBuiltinDecoration(decoration_manager, var_id,
uint32_t(spv::BuiltIn::HelperInvocation));
}
if (execution_model == spv::ExecutionModel::IntersectionKHR ||
execution_model == spv::ExecutionModel::IntersectionNV) {
if (HasBuiltinDecoration(decoration_manager, var_id,
uint32_t(spv::BuiltIn::RayTmaxKHR))) {
return true;
}
}
switch (execution_model) {
case spv::ExecutionModel::RayGenerationKHR:
case spv::ExecutionModel::ClosestHitKHR:
case spv::ExecutionModel::MissKHR:
case spv::ExecutionModel::CallableKHR:
case spv::ExecutionModel::IntersectionKHR:
return HasBuiltinForRayTracingVolatileSemantics(decoration_manager,
var_id);
default:
return false;
}
}
} // namespace opt
} // namespace spvtools