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https://github.com/KhronosGroup/SPIRV-Tools
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f12c40f5a6
This fuzzer pass: For each zero-like constant, either finds the existing definition of the corresponding toggled one (OpConstantNull becomes zero-valued scalar OpConstant or vice versa) or creates a new one if it doesn't exist and records that the two are synonyms For each use of these constants, probabilistically decides whether to change it with the corresponding toggled constant id (as described in #3486 ) Only uses inside blocks of instructions are considered and not, for example, in instructions declaring other constants.
124 lines
4.7 KiB
C++
124 lines
4.7 KiB
C++
// Copyright (c) 2020 Stefano Milizia
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// Copyright (c) 2020 Google LLC
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#include "source/fuzz/fuzzer_pass_interchange_zero_like_constants.h"
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#include "source/fuzz/fuzzer_util.h"
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#include "source/fuzz/id_use_descriptor.h"
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#include "source/fuzz/transformation_record_synonymous_constants.h"
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#include "source/fuzz/transformation_replace_id_with_synonym.h"
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namespace spvtools {
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namespace fuzz {
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FuzzerPassInterchangeZeroLikeConstants::FuzzerPassInterchangeZeroLikeConstants(
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opt::IRContext* ir_context, TransformationContext* transformation_context,
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FuzzerContext* fuzzer_context,
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protobufs::TransformationSequence* transformations)
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: FuzzerPass(ir_context, transformation_context, fuzzer_context,
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transformations) {}
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FuzzerPassInterchangeZeroLikeConstants::
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~FuzzerPassInterchangeZeroLikeConstants() = default;
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uint32_t FuzzerPassInterchangeZeroLikeConstants::FindOrCreateToggledConstant(
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opt::Instruction* declaration) {
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auto constant = GetIRContext()->get_constant_mgr()->FindDeclaredConstant(
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declaration->result_id());
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// This pass only toggles zero-like constants
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if (!constant->IsZero()) {
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return 0;
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}
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if (constant->AsScalarConstant()) {
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return FindOrCreateNullConstant(declaration->type_id());
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} else if (constant->AsNullConstant()) {
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// Add declaration of equivalent scalar constant
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auto kind = constant->type()->kind();
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if (kind == opt::analysis::Type::kBool ||
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kind == opt::analysis::Type::kInteger ||
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kind == opt::analysis::Type::kFloat) {
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return FindOrCreateZeroConstant(declaration->type_id());
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}
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}
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return 0;
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}
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void FuzzerPassInterchangeZeroLikeConstants::MaybeAddUseToReplace(
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opt::Instruction* use_inst, uint32_t use_index, uint32_t replacement_id,
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std::vector<std::pair<protobufs::IdUseDescriptor, uint32_t>>*
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uses_to_replace) {
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// Only consider this use if it is in a block
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if (!GetIRContext()->get_instr_block(use_inst)) {
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return;
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}
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// Get the index of the operand restricted to input operands.
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uint32_t in_operand_index =
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fuzzerutil::InOperandIndexFromOperandIndex(*use_inst, use_index);
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auto id_use_descriptor =
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MakeIdUseDescriptorFromUse(GetIRContext(), use_inst, in_operand_index);
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uses_to_replace->emplace_back(
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std::make_pair(id_use_descriptor, replacement_id));
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}
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void FuzzerPassInterchangeZeroLikeConstants::Apply() {
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// Make vector keeping track of all the uses we want to replace.
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// This is a vector of pairs, where the first element is an id use descriptor
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// identifying the use of a constant id and the second is the id that should
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// be used to replace it.
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std::vector<std::pair<protobufs::IdUseDescriptor, uint32_t>> uses_to_replace;
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for (auto constant : GetIRContext()->GetConstants()) {
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uint32_t constant_id = constant->result_id();
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uint32_t toggled_id = FindOrCreateToggledConstant(constant);
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if (!toggled_id) {
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// Not a zero-like constant
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continue;
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}
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// Record synonymous constants
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ApplyTransformation(
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TransformationRecordSynonymousConstants(constant_id, toggled_id));
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// Find all the uses of the constant and, for each, probabilistically
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// decide whether to replace it.
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GetIRContext()->get_def_use_mgr()->ForEachUse(
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constant_id,
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[this, toggled_id, &uses_to_replace](opt::Instruction* use_inst,
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uint32_t use_index) -> void {
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if (GetFuzzerContext()->ChoosePercentage(
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GetFuzzerContext()
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->GetChanceOfInterchangingZeroLikeConstants())) {
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MaybeAddUseToReplace(use_inst, use_index, toggled_id,
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&uses_to_replace);
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}
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});
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}
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// Replace the ids
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for (auto use_to_replace : uses_to_replace) {
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auto transformation = TransformationReplaceIdWithSynonym(
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use_to_replace.first, use_to_replace.second);
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if (transformation.IsApplicable(GetIRContext(),
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*GetTransformationContext())) {
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transformation.Apply(GetIRContext(), GetTransformationContext());
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*GetTransformations()->add_transformation() = transformation.ToMessage();
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}
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}
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}
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} // namespace fuzz
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} // namespace spvtools
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