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https://github.com/KhronosGroup/SPIRV-Tools
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8d4261bc44
Some transformations (e.g. TransformationAddFunction) rely on running the validator to decide whether the transformation is applicable. A recent change allowed spirv-fuzz to take validator options, to cater for the case where a module should be considered valid under particular conditions. However, validation during the checking of transformations had no access to these validator options. This change introduced TransformationContext, which currently consists of a fact manager and a set of validator options, but could in the future have other fields corresponding to other objects that it is useful to have access to when applying transformations. Now, instead of checking and applying transformations in the context of a FactManager, a TransformationContext is used. This gives access to the fact manager as before, and also access to the validator options when they are needed.
109 lines
4.3 KiB
C++
109 lines
4.3 KiB
C++
// Copyright (c) 2019 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_split_blocks.h"
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#include <vector>
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#include "source/fuzz/instruction_descriptor.h"
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#include "source/fuzz/transformation_split_block.h"
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namespace spvtools {
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namespace fuzz {
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FuzzerPassSplitBlocks::FuzzerPassSplitBlocks(
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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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FuzzerPassSplitBlocks::~FuzzerPassSplitBlocks() = default;
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void FuzzerPassSplitBlocks::Apply() {
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// Gather up pointers to all the blocks in the module. We are then able to
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// iterate over these pointers and split the blocks to which they point;
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// we cannot safely split blocks while we iterate through the module.
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std::vector<opt::BasicBlock*> blocks;
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for (auto& function : *GetIRContext()->module()) {
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for (auto& block : function) {
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blocks.push_back(&block);
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}
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}
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// Now go through all the block pointers that were gathered.
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for (auto& block : blocks) {
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// Probabilistically decide whether to try to split this block.
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if (!GetFuzzerContext()->ChoosePercentage(
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GetFuzzerContext()->GetChanceOfSplittingBlock())) {
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// We are not going to try to split this block.
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continue;
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}
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// TODO(https://github.com/KhronosGroup/SPIRV-Tools/issues/2964): consider
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// taking a simpler approach to identifying the instruction before which
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// to split a block.
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// We are going to try to split this block. We now need to choose where
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// to split it. We describe the instruction before which we would like to
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// split a block via an InstructionDescriptor, details of which are
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// commented in the protobufs definition file.
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std::vector<protobufs::InstructionDescriptor> instruction_descriptors;
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// The initial base instruction is the block label.
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uint32_t base = block->id();
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// Counts the number of times we have seen each opcode since we reset the
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// base instruction.
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std::map<SpvOp, uint32_t> skip_count;
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// Consider every instruction in the block. The label is excluded: it is
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// only necessary to consider it as a base in case the first instruction
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// in the block does not have a result id.
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for (auto& inst : *block) {
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if (inst.HasResultId()) {
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// In the case that the instruction has a result id, we use the
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// instruction as its own base, and clear the skip counts we have
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// collected.
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base = inst.result_id();
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skip_count.clear();
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}
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const SpvOp opcode = inst.opcode();
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instruction_descriptors.emplace_back(MakeInstructionDescriptor(
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base, opcode, skip_count.count(opcode) ? skip_count.at(opcode) : 0));
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if (!inst.HasResultId()) {
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skip_count[opcode] =
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skip_count.count(opcode) ? skip_count.at(opcode) + 1 : 1;
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}
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}
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// Having identified all the places we might be able to split the block,
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// we choose one of them.
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auto transformation = TransformationSplitBlock(
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instruction_descriptors[GetFuzzerContext()->RandomIndex(
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instruction_descriptors)],
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GetFuzzerContext()->GetFreshId());
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// If the position we have chosen turns out to be a valid place to split
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// the block, we apply the split. Otherwise the block just doesn't get
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// split.
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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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