1 // Copyright (c) 2021 ZHOU He
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 #include "remove_unused_interface_variables_pass.h"
16 #include "source/spirv_constant.h"
17 namespace spvtools {
18 namespace opt {
19
20 class RemoveUnusedInterfaceVariablesContext {
21 RemoveUnusedInterfaceVariablesPass& parent_;
22 Instruction& entry_;
23 std::unordered_set<uint32_t> used_variables_;
24 IRContext::ProcessFunction pfn_ =
25 std::bind(&RemoveUnusedInterfaceVariablesContext::processFunction, this,
26 std::placeholders::_1);
27
processFunction(Function * func)28 bool processFunction(Function* func) {
29 for (const auto& basic_block : *func)
30 for (const auto& instruction : basic_block)
31 instruction.ForEachInId([&](const uint32_t* id) {
32 if (used_variables_.count(*id)) return;
33 auto* var = parent_.get_def_use_mgr()->GetDef(*id);
34 if (!var || var->opcode() != SpvOpVariable) return;
35 auto storage_class = var->GetSingleWordInOperand(0);
36 if (storage_class != SpvStorageClassFunction &&
37 (parent_.get_module()->version() >=
38 SPV_SPIRV_VERSION_WORD(1, 4) ||
39 storage_class == SpvStorageClassInput ||
40 storage_class == SpvStorageClassOutput))
41 used_variables_.insert(*id);
42 });
43 return false;
44 }
45
46 public:
RemoveUnusedInterfaceVariablesContext(RemoveUnusedInterfaceVariablesPass & parent,Instruction & entry)47 RemoveUnusedInterfaceVariablesContext(
48 RemoveUnusedInterfaceVariablesPass& parent, Instruction& entry)
49 : parent_(parent), entry_(entry) {}
50
CollectUsedVariables()51 void CollectUsedVariables() {
52 std::queue<uint32_t> roots;
53 roots.push(entry_.GetSingleWordInOperand(1));
54 parent_.context()->ProcessCallTreeFromRoots(pfn_, &roots);
55 }
56
ShouldModify()57 bool ShouldModify() {
58 std::unordered_set<uint32_t> old_variables;
59 for (int i = entry_.NumInOperands() - 1; i >= 3; --i) {
60 auto variable = entry_.GetInOperand(i).words[0];
61 if (!used_variables_.count(variable)) return true; // It is unused.
62 if (old_variables.count(variable)) return true; // It is duplicate.
63 old_variables.insert(variable);
64 }
65 if (old_variables.size() != used_variables_.size()) // Missing IDs.
66 return true;
67 return false;
68 }
69
Modify()70 void Modify() {
71 for (int i = entry_.NumInOperands() - 1; i >= 3; --i)
72 entry_.RemoveInOperand(i);
73 for (auto id : used_variables_) {
74 entry_.AddOperand(Operand(SPV_OPERAND_TYPE_ID, {id}));
75 }
76 }
77 };
78
79 RemoveUnusedInterfaceVariablesPass::Status
Process()80 RemoveUnusedInterfaceVariablesPass::Process() {
81 bool modified = false;
82 for (auto& entry : get_module()->entry_points()) {
83 RemoveUnusedInterfaceVariablesContext context(*this, entry);
84 context.CollectUsedVariables();
85 if (context.ShouldModify()) {
86 context.Modify();
87 modified = true;
88 }
89 }
90 return (modified ? Status::SuccessWithChange : Status::SuccessWithoutChange);
91 }
92 } // namespace opt
93 } // namespace spvtools