SPIRV-Tools/source/fuzz/fuzzer_pass_add_synonyms.cpp
Alastair Donaldson 9c4481419e
spirv-fuzz: Allow inapplicable transformations to be ignored (#4407)
spirv-fuzz features transformations that should be applicable by
construction. Assertions are used to detect when such transformations
turn out to be inapplicable. Failures of such assertions indicate bugs
in the fuzzer. However, when using the fuzzer at scale (e.g. in
ClusterFuzz) reports of these assertion failures create noise, and
cause the fuzzer to exit early. This change adds an option whereby
inapplicable transformations can be ignored. This reduces noise and
allows fuzzing to continue even when a transformation that should be
applicable but is not has been erroneously created.
2021-07-28 22:59:37 +01:00

135 lines
5.6 KiB
C++

// Copyright (c) 2020 Vasyl Teliman
//
// 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_synonyms.h"
#include "source/fuzz/fuzzer_context.h"
#include "source/fuzz/fuzzer_util.h"
#include "source/fuzz/instruction_descriptor.h"
#include "source/fuzz/transformation_add_synonym.h"
namespace spvtools {
namespace fuzz {
FuzzerPassAddSynonyms::FuzzerPassAddSynonyms(
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 FuzzerPassAddSynonyms::Apply() {
ForEachInstructionWithInstructionDescriptor(
[this](opt::Function* function, opt::BasicBlock* block,
opt::BasicBlock::iterator inst_it,
const protobufs::InstructionDescriptor& instruction_descriptor) {
if (GetTransformationContext()->GetFactManager()->BlockIsDead(
block->id())) {
// Don't create synonyms in dead blocks.
return;
}
// Skip |inst_it| if we can't insert anything above it. OpIAdd is just
// a representative of some instruction that might be produced by the
// transformation.
if (!fuzzerutil::CanInsertOpcodeBeforeInstruction(SpvOpIAdd, inst_it)) {
return;
}
if (!GetFuzzerContext()->ChoosePercentage(
GetFuzzerContext()->GetChanceOfAddingSynonyms())) {
return;
}
auto synonym_type = GetFuzzerContext()->GetRandomSynonymType();
// Select all instructions that can be used to create a synonym to.
auto available_instructions = FindAvailableInstructions(
function, block, inst_it,
[synonym_type, this](opt::IRContext* ir_context,
opt::Instruction* inst) {
// Check that we can create a synonym to |inst| as described by
// the |synonym_type| and insert it before |inst_it|.
return TransformationAddSynonym::IsInstructionValid(
ir_context, *GetTransformationContext(), inst, synonym_type);
});
if (available_instructions.empty()) {
return;
}
const auto* existing_synonym =
available_instructions[GetFuzzerContext()->RandomIndex(
available_instructions)];
// Make sure the module contains all instructions required to apply the
// transformation.
switch (synonym_type) {
case protobufs::TransformationAddSynonym::ADD_ZERO:
case protobufs::TransformationAddSynonym::SUB_ZERO:
case protobufs::TransformationAddSynonym::LOGICAL_OR:
case protobufs::TransformationAddSynonym::BITWISE_OR:
case protobufs::TransformationAddSynonym::BITWISE_XOR:
// Create a zero constant to be used as an operand of the synonymous
// instruction.
FindOrCreateZeroConstant(existing_synonym->type_id(), false);
break;
case protobufs::TransformationAddSynonym::MUL_ONE:
case protobufs::TransformationAddSynonym::LOGICAL_AND: {
const auto* existing_synonym_type =
GetIRContext()->get_type_mgr()->GetType(
existing_synonym->type_id());
assert(existing_synonym_type && "Instruction has invalid type");
if (const auto* vector = existing_synonym_type->AsVector()) {
auto element_type_id =
GetIRContext()->get_type_mgr()->GetId(vector->element_type());
assert(element_type_id && "Vector's element type is invalid");
auto one_word = vector->element_type()->AsFloat()
? fuzzerutil::FloatToWord(1)
: 1u;
FindOrCreateCompositeConstant(
std::vector<uint32_t>(
vector->element_count(),
FindOrCreateConstant({one_word}, element_type_id, false)),
existing_synonym->type_id(), false);
} else {
FindOrCreateConstant(
{existing_synonym_type->AsFloat() ? fuzzerutil::FloatToWord(1)
: 1u},
existing_synonym->type_id(), false);
}
} break;
default:
// This assertion will fail if some SynonymType is missing from the
// switch statement.
assert(
!TransformationAddSynonym::IsAdditionalConstantRequired(
synonym_type) &&
"|synonym_type| requires an additional constant to be present "
"in the module");
break;
}
ApplyTransformation(TransformationAddSynonym(
existing_synonym->result_id(), synonym_type,
GetFuzzerContext()->GetFreshId(), instruction_descriptor));
});
}
} // namespace fuzz
} // namespace spvtools