SPIRV-Tools/source/fuzz/fuzzer_pass_add_dead_continues.cpp
Alastair Donaldson 1a89ac8b28
Transformation and fuzzer pass to add dead continues (#2758)
Similar to the existing 'add dead breaks' pass, this adds a pass to
add dead continues to blocks in loops where such a transformation is
viable.  Various functionality common to this new pass and 'add dead
breaks' has been factored into 'fuzzer_util', and some small
improvements to 'add dead breaks' that were identified while reviewing
that code again have been applied.

Fixes #2719.
2019-07-25 13:50:33 +01:00

61 lines
2.5 KiB
C++

// Copyright (c) 2019 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/fuzz/fuzzer_pass_add_dead_continues.h"
#include "source/fuzz/transformation_add_dead_continue.h"
#include "source/opt/ir_context.h"
namespace spvtools {
namespace fuzz {
FuzzerPassAddDeadContinues::FuzzerPassAddDeadContinues(
opt::IRContext* ir_context, FactManager* fact_manager,
FuzzerContext* fuzzer_context,
protobufs::TransformationSequence* transformations)
: FuzzerPass(ir_context, fact_manager, fuzzer_context, transformations) {}
FuzzerPassAddDeadContinues::~FuzzerPassAddDeadContinues() = default;
void FuzzerPassAddDeadContinues::Apply() {
// Consider every block in every function.
for (auto& function : *GetIRContext()->module()) {
for (auto& block : function) {
// Make a transformation to add a dead continue from this node; if the
// node turns out to be inappropriate (e.g. by not being in a loop) the
// precondition for the transformation will fail and it will be ignored.
//
// TODO(afd): right now we completely ignore OpPhi instructions at
// merge blocks. This will lead to interesting opportunities being
// missed.
auto candidate_transformation = TransformationAddDeadContinue(
block.id(), GetFuzzerContext()->GetRandomGenerator()->RandomBool(),
{});
// Probabilistically decide whether to apply the transformation in the
// case that it is applicable.
if (candidate_transformation.IsApplicable(GetIRContext(),
*GetFactManager()) &&
GetFuzzerContext()->GetRandomGenerator()->RandomPercentage() >
GetFuzzerContext()->GetChanceOfAddingDeadContinue()) {
candidate_transformation.Apply(GetIRContext(), GetFactManager());
*GetTransformations()->add_transformation() =
candidate_transformation.ToMessage();
}
}
}
}
} // namespace fuzz
} // namespace spvtools