SPIRV-Tools/source/fuzz/fuzzer_pass_add_dead_continues.cpp
Alastair Donaldson 8d4261bc44
spirv-fuzz: Introduce TransformationContext (#3272)
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.
2020-04-02 15:54:46 +01:00

93 lines
3.9 KiB
C++

// 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)
: FuzzerPass(ir_context, transformation_context, fuzzer_context,
transformations) {}
FuzzerPassAddDeadContinues::~FuzzerPassAddDeadContinues() = default;
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.
//
// TODO(https://github.com/KhronosGroup/SPIRV-Tools/issues/3177):
// If we have a way to communicate to the fact manager
// that a specific id use is irrelevant and could be replaced with
// something else, we should add such a fact about the zero
// provided as an OpPhi operand
phi_ids.push_back(FindOrCreateZeroConstant(phi->type_id()));
});
}
// 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(), GetFuzzerContext()->ChooseEven(), std::move(phi_ids));
// Probabilistically decide whether to apply the transformation in the
// case that it is applicable.
if (candidate_transformation.IsApplicable(GetIRContext(),
*GetTransformationContext()) &&
GetFuzzerContext()->ChoosePercentage(
GetFuzzerContext()->GetChanceOfAddingDeadContinue())) {
candidate_transformation.Apply(GetIRContext(),
GetTransformationContext());
*GetTransformations()->add_transformation() =
candidate_transformation.ToMessage();
}
}
}
}
} // namespace fuzz
} // namespace spvtools