SPIRV-Tools/source/opt/private_to_local_pass.cpp

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// Copyright (c) 2017 Google Inc.
//
// 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/private_to_local_pass.h"
#include <memory>
#include <utility>
#include <vector>
#include "source/opt/ir_context.h"
#include "source/spirv_constant.h"
namespace spvtools {
namespace opt {
namespace {
constexpr uint32_t kVariableStorageClassInIdx = 0;
constexpr uint32_t kSpvTypePointerTypeIdInIdx = 1;
} // namespace
Pass::Status PrivateToLocalPass::Process() {
bool modified = false;
// Private variables require the shader capability. If this is not a shader,
// there is no work to do.
if (context()->get_feature_mgr()->HasCapability(spv::Capability::Addresses))
return Status::SuccessWithoutChange;
std::vector<std::pair<Instruction*, Function*>> variables_to_move;
std::unordered_set<uint32_t> localized_variables;
for (auto& inst : context()->types_values()) {
if (inst.opcode() != spv::Op::OpVariable) {
continue;
}
if (spv::StorageClass(inst.GetSingleWordInOperand(
kVariableStorageClassInIdx)) != spv::StorageClass::Private) {
continue;
}
Function* target_function = FindLocalFunction(inst);
if (target_function != nullptr) {
variables_to_move.push_back({&inst, target_function});
}
}
modified = !variables_to_move.empty();
for (auto p : variables_to_move) {
if (!MoveVariable(p.first, p.second)) {
return Status::Failure;
}
localized_variables.insert(p.first->result_id());
}
if (get_module()->version() >= SPV_SPIRV_VERSION_WORD(1, 4)) {
// In SPIR-V 1.4 and later entry points must list private storage class
// variables that are statically used by the entry point. Go through the
// entry points and remove any references to variables that were localized.
for (auto& entry : get_module()->entry_points()) {
std::vector<Operand> new_operands;
for (uint32_t i = 0; i < entry.NumInOperands(); ++i) {
// Execution model, function id and name are always kept.
if (i < 3 ||
!localized_variables.count(entry.GetSingleWordInOperand(i))) {
new_operands.push_back(entry.GetInOperand(i));
}
}
if (new_operands.size() != entry.NumInOperands()) {
entry.SetInOperands(std::move(new_operands));
context()->AnalyzeUses(&entry);
}
}
}
return (modified ? Status::SuccessWithChange : Status::SuccessWithoutChange);
}
Function* PrivateToLocalPass::FindLocalFunction(const Instruction& inst) const {
bool found_first_use = false;
Function* target_function = nullptr;
context()->get_def_use_mgr()->ForEachUser(
inst.result_id(),
[&target_function, &found_first_use, this](Instruction* use) {
BasicBlock* current_block = context()->get_instr_block(use);
if (current_block == nullptr) {
return;
}
if (!IsValidUse(use)) {
found_first_use = true;
target_function = nullptr;
return;
}
Function* current_function = current_block->GetParent();
if (!found_first_use) {
found_first_use = true;
target_function = current_function;
} else if (target_function != current_function) {
target_function = nullptr;
}
});
return target_function;
} // namespace opt
bool PrivateToLocalPass::MoveVariable(Instruction* variable,
Function* function) {
// The variable needs to be removed from the global section, and placed in the
// header of the function. First step remove from the global list.
variable->RemoveFromList();
std::unique_ptr<Instruction> var(variable); // Take ownership.
context()->ForgetUses(variable);
// Update the storage class of the variable.
variable->SetInOperand(kVariableStorageClassInIdx,
{uint32_t(spv::StorageClass::Function)});
// Update the type as well.
uint32_t new_type_id = GetNewType(variable->type_id());
if (new_type_id == 0) {
return false;
}
variable->SetResultType(new_type_id);
// Place the variable at the start of the first basic block.
context()->AnalyzeUses(variable);
context()->set_instr_block(variable, &*function->begin());
function->begin()->begin()->InsertBefore(std::move(var));
// Update uses where the type may have changed.
return UpdateUses(variable);
}
uint32_t PrivateToLocalPass::GetNewType(uint32_t old_type_id) {
auto type_mgr = context()->get_type_mgr();
Instruction* old_type_inst = get_def_use_mgr()->GetDef(old_type_id);
uint32_t pointee_type_id =
old_type_inst->GetSingleWordInOperand(kSpvTypePointerTypeIdInIdx);
uint32_t new_type_id =
type_mgr->FindPointerToType(pointee_type_id, spv::StorageClass::Function);
if (new_type_id != 0) {
context()->UpdateDefUse(context()->get_def_use_mgr()->GetDef(new_type_id));
}
return new_type_id;
}
bool PrivateToLocalPass::IsValidUse(const Instruction* inst) const {
// The cases in this switch have to match the cases in |UpdateUse|.
// If we don't know how to update it, it is not valid.
if (inst->GetCommonDebugOpcode() == CommonDebugInfoDebugGlobalVariable) {
return true;
}
switch (inst->opcode()) {
case spv::Op::OpLoad:
case spv::Op::OpStore:
case spv::Op::OpImageTexelPointer: // Treat like a load
return true;
case spv::Op::OpAccessChain:
return context()->get_def_use_mgr()->WhileEachUser(
inst, [this](const Instruction* user) {
if (!IsValidUse(user)) return false;
return true;
});
case spv::Op::OpName:
return true;
default:
return spvOpcodeIsDecoration(inst->opcode());
}
}
bool PrivateToLocalPass::UpdateUse(Instruction* inst, Instruction* user) {
// The cases in this switch have to match the cases in |IsValidUse|. If we
// don't think it is valid, the optimization will not view the variable as a
// candidate, and therefore the use will not be updated.
if (inst->GetCommonDebugOpcode() == CommonDebugInfoDebugGlobalVariable) {
context()->get_debug_info_mgr()->ConvertDebugGlobalToLocalVariable(inst,
user);
return true;
}
switch (inst->opcode()) {
case spv::Op::OpLoad:
case spv::Op::OpStore:
case spv::Op::OpImageTexelPointer: // Treat like a load
// The type is fine because it is the type pointed to, and that does not
// change.
break;
case spv::Op::OpAccessChain: {
context()->ForgetUses(inst);
uint32_t new_type_id = GetNewType(inst->type_id());
if (new_type_id == 0) {
return false;
}
inst->SetResultType(new_type_id);
context()->AnalyzeUses(inst);
// Update uses where the type may have changed.
if (!UpdateUses(inst)) {
return false;
}
} break;
case spv::Op::OpName:
case spv::Op::OpEntryPoint: // entry points will be updated separately.
break;
default:
assert(spvOpcodeIsDecoration(inst->opcode()) &&
"Do not know how to update the type for this instruction.");
break;
}
return true;
}
bool PrivateToLocalPass::UpdateUses(Instruction* inst) {
uint32_t id = inst->result_id();
std::vector<Instruction*> uses;
context()->get_def_use_mgr()->ForEachUser(
id, [&uses](Instruction* use) { uses.push_back(use); });
for (Instruction* use : uses) {
if (!UpdateUse(use, inst)) {
return false;
}
}
return true;
}
} // namespace opt
} // namespace spvtools