1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
|
// 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_
|
