1// Copyright (c) 2018 Google LLC.
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_LOOP_FUSION_PASS_H_
16#define SOURCE_OPT_LOOP_FUSION_PASS_H_
17
18#include "source/opt/pass.h"
19
20namespace spvtools {
21namespace opt {
22
23// Implements a loop fusion pass.
24// This pass will look for adjacent loops that are compatible and legal to be
25// fused. It will fuse all such loops as long as the register usage for the
26// fused loop stays under the threshold defined by |max_registers_per_loop|.
27class LoopFusionPass : public Pass {
28 public:
29 explicit LoopFusionPass(size_t max_registers_per_loop)
30 : Pass(), max_registers_per_loop_(max_registers_per_loop) {}
31
32 const char* name() const override { return "loop-fusion"; }
33
34 // Processes the given |module|. Returns Status::Failure if errors occur when
35 // processing. Returns the corresponding Status::Success if processing is
36 // succesful to indicate whether changes have been made to the modue.
37 Status Process() override;
38
39 private:
40 // Fuse loops in |function| if compatible, legal and the fused loop won't use
41 // too many registers.
42 bool ProcessFunction(Function* function);
43
44 // The maximum number of registers a fused loop is allowed to use.
45 size_t max_registers_per_loop_;
46};
47
48} // namespace opt
49} // namespace spvtools
50
51#endif // SOURCE_OPT_LOOP_FUSION_PASS_H_
52