1// Copyright (c) 2017 Google Inc.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7// http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15#ifndef SOURCE_OPT_STRENGTH_REDUCTION_PASS_H_
16#define SOURCE_OPT_STRENGTH_REDUCTION_PASS_H_
17
18#include "source/opt/def_use_manager.h"
19#include "source/opt/ir_context.h"
20#include "source/opt/module.h"
21#include "source/opt/pass.h"
22
23namespace spvtools {
24namespace opt {
25
26// See optimizer.hpp for documentation.
27class StrengthReductionPass : public Pass {
28 public:
29 const char* name() const override { return "strength-reduction"; }
30 Status Process() override;
31
32 private:
33 // Replaces multiple by power of 2 with an equivalent bit shift.
34 // Returns true if something changed.
35 bool ReplaceMultiplyByPowerOf2(BasicBlock::iterator*);
36
37 // Scan the types and constants in the module looking for the the integer
38 // types that we are
39 // interested in. The shift operation needs a small unsigned integer. We
40 // need to find
41 // them or create them. We do not want duplicates.
42 void FindIntTypesAndConstants();
43
44 // Get the id for the given constant. If it does not exist, it will be
45 // created. The parameter must be between 0 and 32 inclusive.
46 uint32_t GetConstantId(uint32_t);
47
48 // Replaces certain instructions in function bodies with presumably cheaper
49 // ones. Returns true if something changed.
50 bool ScanFunctions();
51
52 // Type ids for the types of interest, or 0 if they do not exist.
53 uint32_t int32_type_id_;
54 uint32_t uint32_type_id_;
55
56 // constant_ids[i] is the id for unsigned integer constant i.
57 // We set the limit at 32 because a bit shift of a 32-bit integer does not
58 // need a value larger than 32.
59 uint32_t constant_ids_[33];
60};
61
62} // namespace opt
63} // namespace spvtools
64
65#endif // SOURCE_OPT_STRENGTH_REDUCTION_PASS_H_
66