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// Copyright (c) 2020 Stefano Milizia
// Copyright (c) 2020 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_interchange_zero_like_constants.h"
#include "source/fuzz/fuzzer_util.h"
#include "source/fuzz/id_use_descriptor.h"
#include "source/fuzz/transformation_record_synonymous_constants.h"
#include "source/fuzz/transformation_replace_id_with_synonym.h"
namespace spvtools {
namespace fuzz {
FuzzerPassInterchangeZeroLikeConstants::FuzzerPassInterchangeZeroLikeConstants(
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) {}
uint32_t FuzzerPassInterchangeZeroLikeConstants::FindOrCreateToggledConstant(
opt::Instruction* declaration) {
// |declaration| must not be a specialization constant because we do not know
// the value of specialization constants.
if (opt::IsSpecConstantInst(declaration->opcode())) {
return 0;
}
auto constant = GetIRContext()->get_constant_mgr()->FindDeclaredConstant(
declaration->result_id());
// This pass only toggles zero-like constants
if (!constant->IsZero()) {
return 0;
}
if (constant->AsScalarConstant()) {
return FindOrCreateNullConstant(declaration->type_id());
} else if (constant->AsNullConstant()) {
// Add declaration of equivalent scalar constant
auto kind = constant->type()->kind();
if (kind == opt::analysis::Type::kBool ||
kind == opt::analysis::Type::kInteger ||
kind == opt::analysis::Type::kFloat) {
return FindOrCreateZeroConstant(declaration->type_id(), false);
}
}
return 0;
}
void FuzzerPassInterchangeZeroLikeConstants::Apply() {
// Make vector keeping track of all the uses we want to replace.
// This is a vector of pairs, where the first element is an id use descriptor
// identifying the use of a constant id and the second is the id that should
// be used to replace it.
std::vector<std::pair<protobufs::IdUseDescriptor, uint32_t>> uses_to_replace;
for (auto constant : GetIRContext()->GetConstants()) {
uint32_t constant_id = constant->result_id();
if (GetTransformationContext()->GetFactManager()->IdIsIrrelevant(
constant_id)) {
continue;
}
uint32_t toggled_id = FindOrCreateToggledConstant(constant);
if (!toggled_id) {
// Not a zero-like constant
continue;
}
assert(!GetTransformationContext()->GetFactManager()->IdIsIrrelevant(
toggled_id) &&
"FindOrCreateToggledConstant can't produce an irrelevant id");
// Record synonymous constants
ApplyTransformation(
TransformationRecordSynonymousConstants(constant_id, toggled_id));
// Find all the uses of the constant and, for each, probabilistically
// decide whether to replace it.
GetIRContext()->get_def_use_mgr()->ForEachUse(
constant_id,
[this, toggled_id, &uses_to_replace](opt::Instruction* use_inst,
uint32_t use_index) -> void {
if (GetFuzzerContext()->ChoosePercentage(
GetFuzzerContext()
->GetChanceOfInterchangingZeroLikeConstants())) {
MaybeAddUseToReplace(use_inst, use_index, toggled_id,
&uses_to_replace);
}
});
}
// Replace the ids if it is allowed.
for (auto use_to_replace : uses_to_replace) {
MaybeApplyTransformation(TransformationReplaceIdWithSynonym(
use_to_replace.first, use_to_replace.second));
}
}
} // namespace fuzz
} // namespace spvtools
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