source/fuzz/fuzzer_pass_merge_blocks.cpp

   1 // Copyright (c) 2019 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/fuzz/fuzzer_pass_merge_blocks.h"
  16
  17 #include <vector>
  18
  19 #include "source/fuzz/transformation_merge_blocks.h"
  20
  21 namespace spvtools {
  22 namespace fuzz {
  23
  24 FuzzerPassMergeBlocks::FuzzerPassMergeBlocks(
  25     opt::IRContext* ir_context, TransformationContext* transformation_context,
  26     FuzzerContext* fuzzer_context,
  27     protobufs::TransformationSequence* transformations,
  28     bool ignore_inapplicable_transformations)
  29     : FuzzerPass(ir_context, transformation_context, fuzzer_context,
  30                  transformations, ignore_inapplicable_transformations) {}
  31
  32 void FuzzerPassMergeBlocks::Apply() {
  33   // First we populate a sequence of transformations that we might consider
  34   // applying.
  35   std::vector<TransformationMergeBlocks> potential_transformations;
  36   // We do this by considering every block of every function.
  37   for (auto& function : *GetIRContext()->module()) {
  38     for (auto& block : function) {
  39       // We probabilistically decide to ignore some blocks.
  40       if (!GetFuzzerContext()->ChoosePercentage(
  41               GetFuzzerContext()->GetChanceOfMergingBlocks())) {
  42         continue;
  43       }
  44       // For other blocks, we add a transformation to merge the block into its
  45       // predecessor if that transformation would be applicable.
  46       TransformationMergeBlocks transformation(block.id());
  47       if (transformation.IsApplicable(GetIRContext(),
  48                                       *GetTransformationContext())) {
  49         potential_transformations.push_back(transformation);
  50       }
  51     }
  52   }
  53
  54   while (!potential_transformations.empty()) {
  55     auto transformation =
  56         GetFuzzerContext()->RemoveAtRandomIndex(&potential_transformations);
  57     MaybeApplyTransformation(transformation);
  58   }
  59 }
  60
  61 }  // namespace fuzz
  62 }  // namespace spvtools