mirror of
https://github.com/KhronosGroup/SPIRV-Tools
synced 2024-11-26 21:30:07 +00:00
4a00a80c40
This pass randomly add breaks to the merge blocks of selection and loop constructs, such that the breaking edges will not be dynamically reachable.
106 lines
4.7 KiB
C++
106 lines
4.7 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_breaks.h"
|
|
|
|
#include "source/fuzz/transformation_add_dead_break.h"
|
|
#include "source/opt/ir_context.h"
|
|
|
|
namespace spvtools {
|
|
namespace fuzz {
|
|
|
|
FuzzerPassAddDeadBreaks::FuzzerPassAddDeadBreaks(
|
|
opt::IRContext* ir_context, FactManager* fact_manager,
|
|
FuzzerContext* fuzzer_context,
|
|
protobufs::TransformationSequence* transformations)
|
|
: FuzzerPass(ir_context, fact_manager, fuzzer_context, transformations) {}
|
|
|
|
FuzzerPassAddDeadBreaks::~FuzzerPassAddDeadBreaks() = default;
|
|
|
|
void FuzzerPassAddDeadBreaks::Apply() {
|
|
// We first collect up lots of possibly-applicable transformations.
|
|
std::vector<protobufs::TransformationAddDeadBreak> candidate_transformations;
|
|
// We consider each function separately.
|
|
for (auto& function : *GetIRContext()->module()) {
|
|
// For a given function, we find all the merge blocks in that function.
|
|
std::vector<uint32_t> merge_block_ids;
|
|
for (auto& block : function) {
|
|
auto maybe_merge_id = block.MergeBlockIdIfAny();
|
|
if (maybe_merge_id) {
|
|
merge_block_ids.push_back(maybe_merge_id);
|
|
}
|
|
}
|
|
// We rather aggressively consider the possibility of adding a break from
|
|
// every block in the function to every merge block. Many of these will be
|
|
// inapplicable as they would be illegal. That's OK - we later discard the
|
|
// ones that turn out to be no good.
|
|
for (auto& block : function) {
|
|
for (auto merge_block_id : merge_block_ids) {
|
|
// TODO(afd): right now we completely ignore OpPhi instructions at
|
|
// merge blocks. This will lead to interesting opportunities being
|
|
// missed.
|
|
std::vector<uint32_t> phi_ids;
|
|
auto candidate_transformation =
|
|
transformation::MakeTransformationAddDeadBreak(
|
|
block.id(), merge_block_id,
|
|
GetFuzzerContext()->GetRandomGenerator()->RandomBool(),
|
|
std::move(phi_ids));
|
|
if (transformation::IsApplicable(candidate_transformation,
|
|
GetIRContext(), *GetFactManager())) {
|
|
// Only consider a transformation as a candidate if it is applicable.
|
|
candidate_transformations.push_back(
|
|
std::move(candidate_transformation));
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
// Go through the candidate transformations that were accumulated,
|
|
// probabilistically deciding whether to consider each one further and
|
|
// applying the still-applicable ones that are considered further.
|
|
//
|
|
// We iterate through the candidate transformations in a random order by
|
|
// repeatedly removing a random candidate transformation from the sequence
|
|
// until no candidate transformations remain. This is done because
|
|
// transformations can potentially disable one another, so that iterating
|
|
// through them in order would lead to a higher probability of
|
|
// transformations appearing early in the sequence being applied compared
|
|
// with later transformations.
|
|
while (!candidate_transformations.empty()) {
|
|
// Choose a random index into the sequence of remaining candidate
|
|
// transformations.
|
|
auto index = GetFuzzerContext()->GetRandomGenerator()->RandomUint32(
|
|
static_cast<uint32_t>(candidate_transformations.size()));
|
|
// Remove the transformation at the chosen index from the sequence.
|
|
auto transformation = std::move(candidate_transformations[index]);
|
|
candidate_transformations.erase(candidate_transformations.begin() + index);
|
|
// Probabilistically decide whether to try to apply it vs. ignore it.
|
|
if (GetFuzzerContext()->GetRandomGenerator()->RandomPercentage() >
|
|
GetFuzzerContext()->GetChanceOfAddingDeadBreak()) {
|
|
continue;
|
|
}
|
|
// If the transformation can be applied, apply it and add it to the
|
|
// sequence of transformations that have been applied.
|
|
if (transformation::IsApplicable(transformation, GetIRContext(),
|
|
*GetFactManager())) {
|
|
transformation::Apply(transformation, GetIRContext(), GetFactManager());
|
|
*GetTransformations()->add_transformation()->mutable_add_dead_break() =
|
|
transformation;
|
|
}
|
|
}
|
|
}
|
|
|
|
} // namespace fuzz
|
|
} // namespace spvtools
|