1 // Copyright (c) 2019 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 #include "source/opt/generate_webgpu_initializers_pass.h"
16 #include "source/opt/ir_context.h"
17
18 namespace spvtools {
19 namespace opt {
20
21 using inst_iterator = InstructionList::iterator;
22
23 namespace {
24
NeedsWebGPUInitializer(Instruction * inst)25 bool NeedsWebGPUInitializer(Instruction* inst) {
26 if (inst->opcode() != SpvOpVariable) return false;
27
28 auto storage_class = inst->GetSingleWordOperand(2);
29 if (storage_class != SpvStorageClassOutput &&
30 storage_class != SpvStorageClassPrivate &&
31 storage_class != SpvStorageClassFunction) {
32 return false;
33 }
34
35 if (inst->NumOperands() > 3) return false;
36
37 return true;
38 }
39
40 } // namespace
41
Process()42 Pass::Status GenerateWebGPUInitializersPass::Process() {
43 auto* module = context()->module();
44 bool changed = false;
45
46 // Handle global/module scoped variables
47 for (auto iter = module->types_values_begin();
48 iter != module->types_values_end(); ++iter) {
49 Instruction* inst = &(*iter);
50
51 if (inst->opcode() == SpvOpConstantNull) {
52 null_constant_type_map_[inst->type_id()] = inst;
53 seen_null_constants_.insert(inst);
54 continue;
55 }
56
57 if (!NeedsWebGPUInitializer(inst)) continue;
58
59 changed = true;
60
61 auto* constant_inst = GetNullConstantForVariable(inst);
62 if (!constant_inst) return Status::Failure;
63
64 if (seen_null_constants_.find(constant_inst) ==
65 seen_null_constants_.end()) {
66 constant_inst->InsertBefore(inst);
67 null_constant_type_map_[inst->type_id()] = inst;
68 seen_null_constants_.insert(inst);
69 }
70 AddNullInitializerToVariable(constant_inst, inst);
71 }
72
73 // Handle local/function scoped variables
74 for (auto func = module->begin(); func != module->end(); ++func) {
75 auto block = func->entry().get();
76 for (auto iter = block->begin();
77 iter != block->end() && iter->opcode() == SpvOpVariable; ++iter) {
78 Instruction* inst = &(*iter);
79 if (!NeedsWebGPUInitializer(inst)) continue;
80
81 changed = true;
82 auto* constant_inst = GetNullConstantForVariable(inst);
83 if (!constant_inst) return Status::Failure;
84
85 AddNullInitializerToVariable(constant_inst, inst);
86 }
87 }
88
89 return changed ? Status::SuccessWithChange : Status::SuccessWithoutChange;
90 }
91
GetNullConstantForVariable(Instruction * variable_inst)92 Instruction* GenerateWebGPUInitializersPass::GetNullConstantForVariable(
93 Instruction* variable_inst) {
94 auto constant_mgr = context()->get_constant_mgr();
95 auto* def_use_mgr = get_def_use_mgr();
96
97 auto* ptr_inst = def_use_mgr->GetDef(variable_inst->type_id());
98 auto type_id = ptr_inst->GetInOperand(1).words[0];
99 if (null_constant_type_map_.find(type_id) == null_constant_type_map_.end()) {
100 auto* constant_type = context()->get_type_mgr()->GetType(type_id);
101 auto* constant = constant_mgr->GetConstant(constant_type, {});
102 return constant_mgr->GetDefiningInstruction(constant, type_id);
103 } else {
104 return null_constant_type_map_[type_id];
105 }
106 }
107
AddNullInitializerToVariable(Instruction * constant_inst,Instruction * variable_inst)108 void GenerateWebGPUInitializersPass::AddNullInitializerToVariable(
109 Instruction* constant_inst, Instruction* variable_inst) {
110 auto constant_id = constant_inst->result_id();
111 variable_inst->AddOperand(Operand(SPV_OPERAND_TYPE_ID, {constant_id}));
112 get_def_use_mgr()->AnalyzeInstUse(variable_inst);
113 }
114
115 } // namespace opt
116 } // namespace spvtools
117