SPIRV-Tools/source/reduce/reduction_pass.h
Paul Thomson 7d1b176c1d
Improve reducer algorithm and other changes (#2472)
Fix #2475. Fix #2476. 

* Improve reducer algorithm: shrink granularity, remove an early return, no lazy initialization, notify pass if binary is interesting, add comments.
* Add fail-on-validation-error option to fail a reduction if an invalid state is reached; useful for tests.
* Set fail-on-validation-error in tests.
* Improve some documentation comments.
* Add Reducer::AddDefaultReductionPasses so tests (and other library consumers) can add the default reduction passes.
* Add CLIMessageConsumer in test_reduce so we can see messages for tricky tests.
* Remove test RemoveUnreferencedInstructionReductionPassTest_ApplyReduction because it was indirectly testing the reduction algorithm, not the RemoveUnreferencedInstruction pass.
* Tweak tests where needed.
2019-03-26 13:22:31 +00:00

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// Copyright (c) 2018 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_REDUCE_REDUCTION_PASS_H_
#define SOURCE_REDUCE_REDUCTION_PASS_H_
#include <limits>
#include "source/opt/ir_context.h"
#include "source/reduce/reduction_opportunity_finder.h"
#include "spirv-tools/libspirv.hpp"
namespace spvtools {
namespace reduce {
// Abstract class representing a reduction pass, which can be repeatedly
// invoked to find and apply particular reduction opportunities to a SPIR-V
// binary. In the spirit of delta debugging, a pass initially tries to apply
// large chunks of reduction opportunities, iterating through available
// opportunities at a given granularity. When an iteration over available
// opportunities completes, the granularity is reduced and iteration starts
// again, until the minimum granularity is reached.
class ReductionPass {
public:
// Constructs a reduction pass with a given target environment, |target_env|,
// and a given finder of reduction opportunities, |finder|.
explicit ReductionPass(const spv_target_env target_env,
std::unique_ptr<ReductionOpportunityFinder> finder)
: target_env_(target_env),
finder_(std::move(finder)),
index_(0),
granularity_(std::numeric_limits<uint32_t>::max()) {}
// Applies the reduction pass to the given binary by applying a "chunk" of
// reduction opportunities. Returns the new binary if a chunk was applied; in
// this case, before the next call the caller must invoke
// NotifyInteresting(...) to indicate whether the new binary is interesting.
// Returns an empty vector if there are no more chunks left to apply; in this
// case, the index will be reset and the granularity lowered for the next
// round.
std::vector<uint32_t> TryApplyReduction(const std::vector<uint32_t>& binary);
// Notifies the reduction pass whether the binary returned from
// TryApplyReduction is interesting, so that the next call to
// TryApplyReduction will avoid applying the same chunk of opportunities.
void NotifyInteresting(bool interesting);
// Sets a consumer to which relevant messages will be directed.
void SetMessageConsumer(MessageConsumer consumer);
// Returns true if the granularity with which reduction opportunities are
// applied has reached a minimum.
bool ReachedMinimumGranularity() const;
// Returns the name associated with this reduction pass (based on its
// associated finder).
std::string GetName() const;
private:
const spv_target_env target_env_;
const std::unique_ptr<ReductionOpportunityFinder> finder_;
MessageConsumer consumer_;
uint32_t index_;
uint32_t granularity_;
};
} // namespace reduce
} // namespace spvtools
#endif // SOURCE_REDUCE_REDUCTION_PASS_H_