SPIRV-Tools/source/opt/dataflow.cpp
dong-ja c4c6f2ba5c
spirv-opt: Add dataflow analysis framework (#4402)
This PR adds a generic dataflow analysis framework to SPIRV-opt, with the intent of being used in SPIRV-lint. This may also be useful for SPIRV-opt, as existing ad-hoc analyses can be rewritten to use a common framework, but this is not the target of this PR.
2021-08-09 16:43:36 -04:00

92 lines
2.8 KiB
C++

// Copyright (c) 2021 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/dataflow.h"
#include <algorithm>
#include <cstdint>
namespace spvtools {
namespace opt {
bool DataFlowAnalysis::Enqueue(Instruction* inst) {
bool& is_enqueued = on_worklist_[inst];
if (is_enqueued) return false;
is_enqueued = true;
worklist_.push(inst);
return true;
}
DataFlowAnalysis::VisitResult DataFlowAnalysis::RunOnce(
Function* function, bool is_first_iteration) {
InitializeWorklist(function, is_first_iteration);
VisitResult ret = VisitResult::kResultFixed;
while (!worklist_.empty()) {
Instruction* top = worklist_.front();
worklist_.pop();
on_worklist_[top] = false;
VisitResult result = Visit(top);
if (result == VisitResult::kResultChanged) {
EnqueueSuccessors(top);
ret = VisitResult::kResultChanged;
}
}
return ret;
}
void DataFlowAnalysis::Run(Function* function) {
VisitResult result = RunOnce(function, true);
while (result == VisitResult::kResultChanged) {
result = RunOnce(function, false);
}
}
void ForwardDataFlowAnalysis::InitializeWorklist(Function* function,
bool /*is_first_iteration*/) {
context().cfg()->ForEachBlockInReversePostOrder(
function->entry().get(), [this](BasicBlock* bb) {
if (label_position_ == LabelPosition::kLabelsOnly) {
Enqueue(bb->GetLabelInst());
return;
}
if (label_position_ == LabelPosition::kLabelsAtBeginning) {
Enqueue(bb->GetLabelInst());
}
for (Instruction& inst : *bb) {
Enqueue(&inst);
}
if (label_position_ == LabelPosition::kLabelsAtEnd) {
Enqueue(bb->GetLabelInst());
}
});
}
void ForwardDataFlowAnalysis::EnqueueUsers(Instruction* inst) {
context().get_def_use_mgr()->ForEachUser(
inst, [this](Instruction* user) { Enqueue(user); });
}
void ForwardDataFlowAnalysis::EnqueueBlockSuccessors(Instruction* inst) {
if (inst->opcode() != SpvOpLabel) return;
context()
.cfg()
->block(inst->result_id())
->ForEachSuccessorLabel([this](uint32_t* label) {
Enqueue(context().cfg()->block(*label)->GetLabelInst());
});
}
} // namespace opt
} // namespace spvtools