SPIRV-Tools/source/fuzz/fuzzer_pass_add_dead_continues.cpp
Alastair Donaldson 0a07cd1c9a
Add fuzzer pass to replace ids with synonyms (#2857)
If the fuzzer's fact manager knows that ids A and B are synonymous, it
can replace a use of A with a use of B, so long as various conditions
hold (e.g. the definition of B must dominate the use of A, and it is
not legal to replace a use of an OpConstant in a struct's access chain
with a synonym that is not an OpConstant).

This change adds a fuzzer pass to sprinke such synonym replacements
through the module.
2019-09-18 20:47:08 +01:00

60 lines
2.5 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/transformation_add_dead_continue.h"
#include "source/opt/ir_context.h"
namespace spvtools {
namespace fuzz {
FuzzerPassAddDeadContinues::FuzzerPassAddDeadContinues(
opt::IRContext* ir_context, FactManager* fact_manager,
FuzzerContext* fuzzer_context,
protobufs::TransformationSequence* transformations)
: FuzzerPass(ir_context, fact_manager, fuzzer_context, transformations) {}
FuzzerPassAddDeadContinues::~FuzzerPassAddDeadContinues() = default;
void FuzzerPassAddDeadContinues::Apply() {
// Consider every block in every function.
for (auto& function : *GetIRContext()->module()) {
for (auto& block : function) {
// 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.
//
// TODO(https://github.com/KhronosGroup/SPIRV-Tools/issues/2856): right
// now we completely ignore OpPhi instructions at continue targets.
// This will lead to interesting opportunities being missed.
auto candidate_transformation = TransformationAddDeadContinue(
block.id(), GetFuzzerContext()->ChooseEven(), {});
// Probabilistically decide whether to apply the transformation in the
// case that it is applicable.
if (candidate_transformation.IsApplicable(GetIRContext(),
*GetFactManager()) &&
GetFuzzerContext()->ChoosePercentage(
GetFuzzerContext()->GetChanceOfAddingDeadContinue())) {
candidate_transformation.Apply(GetIRContext(), GetFactManager());
*GetTransformations()->add_transformation() =
candidate_transformation.ToMessage();
}
}
}
}
} // namespace fuzz
} // namespace spvtools