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// Copyright (c) 2018 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/reduce/reduction_pass.h"
#include <algorithm>
#include "source/opt/build_module.h"
namespace spvtools {
namespace reduce {
std::vector<uint32_t> ReductionPass::TryApplyReduction(
const std::vector<uint32_t>& binary, uint32_t target_function) {
// We represent modules as binaries because (a) attempts at reduction need to
// end up in binary form to be passed on to SPIR-V-consuming tools, and (b)
// when we apply a reduction step we need to do it on a fresh version of the
// module as if the reduction step proves to be uninteresting we need to
// backtrack; re-parsing from binary provides a very clean way of cloning the
// module.
std::unique_ptr<opt::IRContext> context =
BuildModule(target_env_, consumer_,, binary.size());
std::vector<std::unique_ptr<ReductionOpportunity>> opportunities =
finder_->GetAvailableOpportunities(context.get(), target_function);
// There is no point in having a granularity larger than the number of
// opportunities, so reduce the granularity in this case.
if (granularity_ > opportunities.size()) {
granularity_ = std::max((uint32_t)1, (uint32_t)opportunities.size());
assert(granularity_ > 0);
if (index_ >= opportunities.size()) {
// We have reached the end of the available opportunities and, therefore,
// the end of the round for this pass, so reset the index and decrease the
// granularity for the next round. Return an empty vector to signal the end
// of the round.
index_ = 0;
granularity_ = std::max((uint32_t)1, granularity_ / 2);
return std::vector<uint32_t>();
for (uint32_t i = index_;
i < std::min(index_ + granularity_, (uint32_t)opportunities.size());
++i) {
std::vector<uint32_t> result;
context->module()->ToBinary(&result, false);
return result;
void ReductionPass::SetMessageConsumer(MessageConsumer consumer) {
consumer_ = std::move(consumer);
bool ReductionPass::ReachedMinimumGranularity() const {
assert(granularity_ != 0);
return granularity_ == 1;
std::string ReductionPass::GetName() const { return finder_->GetName(); }
void ReductionPass::NotifyInteresting(bool interesting) {
if (!interesting) {
index_ += granularity_;
} // namespace reduce
} // namespace spvtools