SPIRV-Tools/source/opt/local_redundancy_elimination.h
Steven Perron c2013e248b
Make the constant and type manager analyses. (#2250)
Currently it is impossible to invalidate the constnat and type manager.
However, the compact ids pass changes the ids for the types and
constants, which makes them invalid.  This change will make them
analyses that have to been explicitly marked as preserved by passes.
This will allow compact ids to invalidate them.

Fixes #2220.
2018-12-20 18:00:05 +00:00

69 lines
2.6 KiB
C++

// Copyright (c) 2017 Google Inc.
//
// 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_OPT_LOCAL_REDUNDANCY_ELIMINATION_H_
#define SOURCE_OPT_LOCAL_REDUNDANCY_ELIMINATION_H_
#include <map>
#include "source/opt/ir_context.h"
#include "source/opt/pass.h"
#include "source/opt/value_number_table.h"
namespace spvtools {
namespace opt {
// This pass implements local redundancy elimination. Its goal is to reduce the
// number of times the same value is computed. It works on each basic block
// independently, ie local. For each instruction in a basic block, it gets the
// value number for the result id, |id|, of the instruction. If that value
// number has already been computed in the basic block, it tries to replace the
// uses of |id| by the id that already contains the same value. Then the
// current instruction is deleted.
class LocalRedundancyEliminationPass : public Pass {
public:
const char* name() const override { return "local-redundancy-elimination"; }
Status Process() override;
IRContext::Analysis GetPreservedAnalyses() override {
return IRContext::kAnalysisDefUse |
IRContext::kAnalysisInstrToBlockMapping |
IRContext::kAnalysisDecorations | IRContext::kAnalysisCombinators |
IRContext::kAnalysisCFG | IRContext::kAnalysisDominatorAnalysis |
IRContext::kAnalysisNameMap | IRContext::kAnalysisConstants |
IRContext::kAnalysisTypes;
}
protected:
// Deletes instructions in |block| whose value is in |value_to_ids| or is
// computed earlier in |block|.
//
// |vnTable| must have computed a value number for every result id defined
// in |bb|.
//
// |value_to_ids| is a map from value number to ids. If {vn, id} is in
// |value_to_ids| then vn is the value number of id, and the definition of id
// dominates |bb|.
//
// Returns true if the module is changed.
bool EliminateRedundanciesInBB(BasicBlock* block,
const ValueNumberTable& vnTable,
std::map<uint32_t, uint32_t>* value_to_ids);
};
} // namespace opt
} // namespace spvtools
#endif // SOURCE_OPT_LOCAL_REDUNDANCY_ELIMINATION_H_