1// Copyright (c) 2018 Google LLC
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#include "source/reduce/reduction_pass.h"
16
17#include <algorithm>
18
19#include "source/opt/build_module.h"
20
21namespace spvtools {
22namespace reduce {
23
24std::vector<uint32_t> ReductionPass::TryApplyReduction(
25    const std::vector<uint32_t>& binary, uint32_t target_function) {
26  // We represent modules as binaries because (a) attempts at reduction need to
27  // end up in binary form to be passed on to SPIR-V-consuming tools, and (b)
28  // when we apply a reduction step we need to do it on a fresh version of the
29  // module as if the reduction step proves to be uninteresting we need to
30  // backtrack; re-parsing from binary provides a very clean way of cloning the
31  // module.
32  std::unique_ptr<opt::IRContext> context =
33      BuildModule(target_env_, consumer_, binary.data(), binary.size());
34  assert(context);
35
36  std::vector<std::unique_ptr<ReductionOpportunity>> opportunities =
37      finder_->GetAvailableOpportunities(context.get(), target_function);
38
39  // There is no point in having a granularity larger than the number of
40  // opportunities, so reduce the granularity in this case.
41  if (granularity_ > opportunities.size()) {
42    granularity_ = std::max((uint32_t)1, (uint32_t)opportunities.size());
43  }
44
45  assert(granularity_ > 0);
46
47  if (index_ >= opportunities.size()) {
48    // We have reached the end of the available opportunities and, therefore,
49    // the end of the round for this pass, so reset the index and decrease the
50    // granularity for the next round. Return an empty vector to signal the end
51    // of the round.
52    index_ = 0;
53    granularity_ = std::max((uint32_t)1, granularity_ / 2);
54    return std::vector<uint32_t>();
55  }
56
57  for (uint32_t i = index_;
58       i < std::min(index_ + granularity_, (uint32_t)opportunities.size());
59       ++i) {
60    opportunities[i]->TryToApply();
61  }
62
63  std::vector<uint32_t> result;
64  context->module()->ToBinary(&result, false);
65  return result;
66}
67
68void ReductionPass::SetMessageConsumer(MessageConsumer consumer) {
69  consumer_ = std::move(consumer);
70}
71
72bool ReductionPass::ReachedMinimumGranularity() const {
73  assert(granularity_ != 0);
74  return granularity_ == 1;
75}
76
77std::string ReductionPass::GetName() const { return finder_->GetName(); }
78
79void ReductionPass::NotifyInteresting(bool interesting) {
80  if (!interesting) {
81    index_ += granularity_;
82  }
83}
84
85}  // namespace reduce
86}  // namespace spvtools
87