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// 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.
#ifndef SOURCE_FUZZ_TRANSFORMATION_H_
#define SOURCE_FUZZ_TRANSFORMATION_H_
#include <memory>
#include <unordered_set>
#include "source/fuzz/protobufs/spirvfuzz_protobufs.h"
#include "source/fuzz/transformation_context.h"
#include "source/opt/ir_context.h"
namespace spvtools {
namespace fuzz {
// Rules for transformations
// -------------------------
//
// - Immutability: a transformation must be immutable.
// - Ability to copy and serialize: to ensure that a copy of a transformation,
// possibly saved out to disk and read back again, is indistinguishable
// from the original transformation, thus a transformation must depend
// only on well-defined pieces of state, such as instruction ids. It must
// not rely on state such as pointers to instructions and blocks.
// - Determinism: the effect of a transformation on a module be a deterministic
// function of the module and the transformation. Any randomization should
// be applied before creating the transformation, not during its
// application.
// - Well-defined and precondition: the 'IsApplicable' method should only
// return true if the transformation can be cleanly applied to the given
// module, to mutate it into a valid and semantically-equivalent module, as
// long as the module is initially valid.
// - Ability to test precondition on any valid module: 'IsApplicable' should be
// designed so that it is safe to ask whether a transformation is
// applicable to an arbitrary valid module. For example, if a
// transformation involves a block id, 'IsApplicable' should check whether
// the module indeed has a block with that id, and return false if not. It
// must not assume that there is such a block.
// - Documented precondition: while the implementation of 'IsApplicable' should
// should codify the precondition, the method should be commented in the
// header file for a transformation with a precise English description of
// the precondition.
// - Documented effect: while the implementation of 'Apply' should codify the
// effect of the transformation, the method should be commented in the
// header file for a transformation with a precise English description of
// the effect.
class Transformation {
public:
virtual ~Transformation();
// Factory method to obtain a transformation object from the protobuf
// representation of a transformation given by |message|.
static std::unique_ptr<Transformation> FromMessage(
const protobufs::Transformation& message);
// A precondition that determines whether the transformation can be cleanly
// applied in a semantics-preserving manner to the SPIR-V module given by
// |ir_context|, in the presence of facts and other contextual information
// captured by |transformation_context|.
//
// Preconditions for individual transformations must be documented in the
// associated header file using precise English. The transformation context
// provides access to facts about the module that are known to be true, on
// which the precondition may depend.
virtual bool IsApplicable(
opt::IRContext* ir_context,
const TransformationContext& transformation_context) const = 0;
// Requires that IsApplicable(ir_context, *transformation_context) holds.
// Applies the transformation, mutating |ir_context| and possibly updating
// |transformation_context| with new facts established by the transformation.
virtual void Apply(opt::IRContext* ir_context,
TransformationContext* transformation_context) const = 0;
// Returns the set of fresh ids that appear in the transformation's protobuf
// message.
virtual std::unordered_set<uint32_t> GetFreshIds() const = 0;
// Turns the transformation into a protobuf message for serialization.
virtual protobufs::Transformation ToMessage() const = 0;
// Helper that returns true if and only if (a) |id| is a fresh id for the
// module, and (b) |id| is not in |ids_used_by_this_transformation|, a set of
// ids already known to be in use by a transformation. This is useful when
// checking id freshness for a transformation that uses many ids, all of which
// must be distinct.
static bool CheckIdIsFreshAndNotUsedByThisTransformation(
uint32_t id, opt::IRContext* ir_context,
std::set<uint32_t>* ids_used_by_this_transformation);
};
} // namespace fuzz
} // namespace spvtools
#endif // SOURCE_FUZZ_TRANSFORMATION_H_
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