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// 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/fuzzer_util.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, TransformationContext* transformation_context,
FuzzerContext* fuzzer_context,
protobufs::TransformationSequence* transformations,
bool ignore_inapplicable_transformations)
: FuzzerPass(ir_context, transformation_context, fuzzer_context,
transformations, ignore_inapplicable_transformations) {}
void FuzzerPassAddDeadContinues::Apply() {
// Consider every block in every function.
for (auto& function : *GetIRContext()->module()) {
for (auto& block : function) {
// Get the label id of the continue target of the innermost loop.
auto continue_block_id =
block.IsLoopHeader()
? block.ContinueBlockId()
: GetIRContext()->GetStructuredCFGAnalysis()->LoopContinueBlock(
block.id());
// This transformation is not applicable if current block is not inside a
// loop.
if (continue_block_id == 0) {
continue;
}
auto* continue_block =
fuzzerutil::MaybeFindBlock(GetIRContext(), continue_block_id);
assert(continue_block && "Continue block is null");
// Analyze return type of each OpPhi instruction in the continue target
// and provide an id for the transformation if needed.
std::vector<uint32_t> phi_ids;
// Check whether current block has an edge to the continue target.
// If this is the case, we don't need to do anything.
if (!block.IsSuccessor(continue_block)) {
continue_block->ForEachPhiInst([this, &phi_ids](opt::Instruction* phi) {
// Add an additional operand for OpPhi instruction. Use a constant
// if possible, and an undef otherwise.
if (fuzzerutil::CanCreateConstant(GetIRContext(), phi->type_id())) {
// We mark the constant as irrelevant so that we can replace it with
// a more interesting value later.
phi_ids.push_back(FindOrCreateZeroConstant(phi->type_id(), true));
} else {
phi_ids.push_back(FindOrCreateGlobalUndef(phi->type_id()));
}
});
}
// Make sure the module contains a boolean constant equal to
// |condition_value|.
bool condition_value = GetFuzzerContext()->ChooseEven();
FindOrCreateBoolConstant(condition_value, false);
// 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.
auto candidate_transformation = TransformationAddDeadContinue(
block.id(), condition_value, std::move(phi_ids));
// Probabilistically decide whether to apply the transformation in the
// case that it is applicable.
if (GetFuzzerContext()->ChoosePercentage(
GetFuzzerContext()->GetChanceOfAddingDeadContinue())) {
MaybeApplyTransformation(candidate_transformation);
}
}
}
}
} // namespace fuzz
} // namespace spvtools
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