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// 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_PRIVATE_TO_LOCAL_PASS_H_
#define SOURCE_OPT_PRIVATE_TO_LOCAL_PASS_H_
#include "source/opt/ir_context.h"
#include "source/opt/pass.h"
namespace spvtools {
namespace opt {
// This pass implements total redundancy elimination. This is the same as
// local redundancy elimination except it looks across basic block boundaries.
// An instruction, inst, is totally redundant if there is another instruction
// that dominates inst, and also computes the same value.
class PrivateToLocalPass : public Pass {
public:
const char* name() const override { return "private-to-local"; }
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;
}
private:
// Moves |variable| from the private storage class to the function storage
// class of |function|. Returns false if the variable could not be moved.
bool MoveVariable(Instruction* variable, Function* function);
// |inst| is an instruction declaring a varible. If that variable is
// referenced in a single function and all of uses are valid as defined by
// |IsValidUse|, then that function is returned. Otherwise, the return
// value is |nullptr|.
Function* FindLocalFunction(const Instruction& inst) const;
// Returns true is |inst| is a valid use of a pointer. In this case, a
// valid use is one where the transformation is able to rewrite the type to
// match a change in storage class of the original variable.
bool IsValidUse(const Instruction* inst) const;
// Given the result id of a pointer type, |old_type_id|, this function
// returns the id of a the same pointer type except the storage class has
// been changed to function. If the type does not already exist, it will be
// created. Returns 0 if the new type could not be found or generated.
uint32_t GetNewType(uint32_t old_type_id);
// Updates |inst|, and any instruction dependent on |inst|, to reflect the
// change of the base pointer now pointing to the function storage class.
bool UpdateUse(Instruction* inst, Instruction* user);
bool UpdateUses(Instruction* inst);
};
} // namespace opt
} // namespace spvtools
#endif // SOURCE_OPT_PRIVATE_TO_LOCAL_PASS_H_
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