1 // Copyright (c) 2020 André Perez Maselco
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/fuzz/fuzzer_pass_push_ids_through_variables.h"
16
17 #include "source/fuzz/fuzzer_util.h"
18 #include "source/fuzz/instruction_descriptor.h"
19 #include "source/fuzz/transformation_push_id_through_variable.h"
20
21 namespace spvtools {
22 namespace fuzz {
23
FuzzerPassPushIdsThroughVariables(opt::IRContext * ir_context,TransformationContext * transformation_context,FuzzerContext * fuzzer_context,protobufs::TransformationSequence * transformations,bool ignore_inapplicable_transformations)24 FuzzerPassPushIdsThroughVariables::FuzzerPassPushIdsThroughVariables(
25 opt::IRContext* ir_context, TransformationContext* transformation_context,
26 FuzzerContext* fuzzer_context,
27 protobufs::TransformationSequence* transformations,
28 bool ignore_inapplicable_transformations)
29 : FuzzerPass(ir_context, transformation_context, fuzzer_context,
30 transformations, ignore_inapplicable_transformations) {}
31
Apply()32 void FuzzerPassPushIdsThroughVariables::Apply() {
33 ForEachInstructionWithInstructionDescriptor(
34 [this](opt::Function* function, opt::BasicBlock* block,
35 opt::BasicBlock::iterator instruction_iterator,
36 const protobufs::InstructionDescriptor& instruction_descriptor)
37 -> void {
38 assert(instruction_iterator->opcode() ==
39 instruction_descriptor.target_instruction_opcode() &&
40 "The opcode of the instruction we might insert before must be "
41 "the same as the opcode in the descriptor for the instruction");
42
43 // Randomly decide whether to try pushing an id through a variable.
44 if (!GetFuzzerContext()->ChoosePercentage(
45 GetFuzzerContext()->GetChanceOfPushingIdThroughVariable())) {
46 return;
47 }
48
49 // The block containing the instruction we are going to insert before
50 // must be reachable.
51 if (!GetIRContext()->IsReachable(*block)) {
52 return;
53 }
54
55 // It must be valid to insert OpStore and OpLoad instructions
56 // before the instruction to insert before.
57 if (!fuzzerutil::CanInsertOpcodeBeforeInstruction(
58 SpvOpStore, instruction_iterator) ||
59 !fuzzerutil::CanInsertOpcodeBeforeInstruction(
60 SpvOpLoad, instruction_iterator)) {
61 return;
62 }
63
64 // Randomly decides whether a global or local variable will be added.
65 auto variable_storage_class = GetFuzzerContext()->ChooseEven()
66 ? SpvStorageClassPrivate
67 : SpvStorageClassFunction;
68
69 // Gets the available basic and pointer types.
70 auto basic_type_ids_and_pointers =
71 GetAvailableBasicTypesAndPointers(variable_storage_class);
72 auto& basic_types = basic_type_ids_and_pointers.first;
73
74 // There must be at least some basic types.
75 if (basic_types.empty()) {
76 return;
77 }
78
79 uint32_t basic_type_id =
80 basic_types[GetFuzzerContext()->RandomIndex(basic_types)];
81
82 // Looks for ids that we might wish to consider pushing through a
83 // variable.
84 std::vector<opt::Instruction*> value_instructions =
85 FindAvailableInstructions(
86 function, block, instruction_iterator,
87 [this, basic_type_id, instruction_descriptor](
88 opt::IRContext* ir_context,
89 opt::Instruction* instruction) -> bool {
90 if (!instruction->result_id() || !instruction->type_id()) {
91 return false;
92 }
93
94 if (instruction->type_id() != basic_type_id) {
95 return false;
96 }
97
98 // If the id is irrelevant, we can use it since it will not
99 // participate in DataSynonym fact. Otherwise, we should be
100 // able to produce a synonym out of the id.
101 if (!GetTransformationContext()
102 ->GetFactManager()
103 ->IdIsIrrelevant(instruction->result_id()) &&
104 !fuzzerutil::CanMakeSynonymOf(ir_context,
105 *GetTransformationContext(),
106 *instruction)) {
107 return false;
108 }
109
110 return fuzzerutil::IdIsAvailableBeforeInstruction(
111 ir_context,
112 FindInstruction(instruction_descriptor, ir_context),
113 instruction->result_id());
114 });
115
116 if (value_instructions.empty()) {
117 return;
118 }
119
120 // If the pointer type does not exist, then create it.
121 FindOrCreatePointerType(basic_type_id, variable_storage_class);
122
123 // TODO(https://github.com/KhronosGroup/SPIRV-Tools/issues/3403):
124 // type support here is limited by the FindOrCreateZeroConstant
125 // function.
126 const auto* type_inst =
127 GetIRContext()->get_def_use_mgr()->GetDef(basic_type_id);
128 assert(type_inst);
129 switch (type_inst->opcode()) {
130 case SpvOpTypeBool:
131 case SpvOpTypeFloat:
132 case SpvOpTypeInt:
133 case SpvOpTypeArray:
134 case SpvOpTypeMatrix:
135 case SpvOpTypeVector:
136 case SpvOpTypeStruct:
137 break;
138 default:
139 return;
140 }
141
142 // Create a constant to initialize the variable from. This might update
143 // module's id bound so it must be done before any fresh ids are
144 // computed.
145 auto initializer_id = FindOrCreateZeroConstant(basic_type_id, false);
146
147 // Applies the push id through variable transformation.
148 ApplyTransformation(TransformationPushIdThroughVariable(
149 value_instructions[GetFuzzerContext()->RandomIndex(
150 value_instructions)]
151 ->result_id(),
152 GetFuzzerContext()->GetFreshId(), GetFuzzerContext()->GetFreshId(),
153 variable_storage_class, initializer_id, instruction_descriptor));
154 });
155 }
156
157 } // namespace fuzz
158 } // namespace spvtools
159