1 // Copyright (c) 2020 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/fuzz/fuzzer_pass_add_global_variables.h"
16
17 #include "source/fuzz/transformation_add_global_variable.h"
18 #include "source/fuzz/transformation_add_type_pointer.h"
19
20 namespace spvtools {
21 namespace fuzz {
22
FuzzerPassAddGlobalVariables(opt::IRContext * ir_context,TransformationContext * transformation_context,FuzzerContext * fuzzer_context,protobufs::TransformationSequence * transformations)23 FuzzerPassAddGlobalVariables::FuzzerPassAddGlobalVariables(
24 opt::IRContext* ir_context, TransformationContext* transformation_context,
25 FuzzerContext* fuzzer_context,
26 protobufs::TransformationSequence* transformations)
27 : FuzzerPass(ir_context, transformation_context, fuzzer_context,
28 transformations) {}
29
Apply()30 void FuzzerPassAddGlobalVariables::Apply() {
31 SpvStorageClass variable_storage_class = SpvStorageClassPrivate;
32 for (auto& entry_point : GetIRContext()->module()->entry_points()) {
33 // If the execution model of some entry point is GLCompute,
34 // then the variable storage class may be Workgroup.
35 if (entry_point.GetSingleWordInOperand(0) == SpvExecutionModelGLCompute) {
36 variable_storage_class =
37 GetFuzzerContext()->ChoosePercentage(
38 GetFuzzerContext()->GetChanceOfChoosingWorkgroupStorageClass())
39 ? SpvStorageClassWorkgroup
40 : SpvStorageClassPrivate;
41 break;
42 }
43 }
44
45 auto basic_type_ids_and_pointers =
46 GetAvailableBasicTypesAndPointers(variable_storage_class);
47
48 // These are the basic types that are available to this fuzzer pass.
49 auto& basic_types = basic_type_ids_and_pointers.first;
50
51 // These are the pointers to those basic types that are *initially* available
52 // to the fuzzer pass. The fuzzer pass might add pointer types in cases where
53 // none are available for a given basic type.
54 auto& basic_type_to_pointers = basic_type_ids_and_pointers.second;
55
56 // Probabilistically keep adding global variables.
57 while (GetFuzzerContext()->ChoosePercentage(
58 GetFuzzerContext()->GetChanceOfAddingGlobalVariable())) {
59 // Choose a random basic type; the new variable's type will be a pointer to
60 // this basic type.
61 uint32_t basic_type =
62 basic_types[GetFuzzerContext()->RandomIndex(basic_types)];
63 uint32_t pointer_type_id;
64 std::vector<uint32_t>& available_pointers_to_basic_type =
65 basic_type_to_pointers.at(basic_type);
66 // Determine whether there is at least one pointer to this basic type.
67 if (available_pointers_to_basic_type.empty()) {
68 // There is not. Make one, to use here, and add it to the available
69 // pointers for the basic type so that future variables can potentially
70 // use it.
71 pointer_type_id = GetFuzzerContext()->GetFreshId();
72 available_pointers_to_basic_type.push_back(pointer_type_id);
73 ApplyTransformation(TransformationAddTypePointer(
74 pointer_type_id, variable_storage_class, basic_type));
75 } else {
76 // There is - grab one.
77 pointer_type_id =
78 available_pointers_to_basic_type[GetFuzzerContext()->RandomIndex(
79 available_pointers_to_basic_type)];
80 }
81
82 ApplyTransformation(TransformationAddGlobalVariable(
83 GetFuzzerContext()->GetFreshId(), pointer_type_id,
84 variable_storage_class,
85 variable_storage_class == SpvStorageClassPrivate
86 ? FindOrCreateZeroConstant(basic_type, false)
87 : 0,
88 true));
89 }
90 }
91
92 } // namespace fuzz
93 } // namespace spvtools
94