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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_inline_functions.h"
16 
17 #include "source/fuzz/fuzzer_util.h"
18 #include "source/fuzz/instruction_descriptor.h"
19 #include "source/fuzz/transformation_inline_function.h"
20 #include "source/fuzz/transformation_split_block.h"
21 
22 namespace spvtools {
23 namespace fuzz {
24 
FuzzerPassInlineFunctions(opt::IRContext * ir_context,TransformationContext * transformation_context,FuzzerContext * fuzzer_context,protobufs::TransformationSequence * transformations)25 FuzzerPassInlineFunctions::FuzzerPassInlineFunctions(
26     opt::IRContext* ir_context, TransformationContext* transformation_context,
27     FuzzerContext* fuzzer_context,
28     protobufs::TransformationSequence* transformations)
29     : FuzzerPass(ir_context, transformation_context, fuzzer_context,
30                  transformations) {}
31 
32 FuzzerPassInlineFunctions::~FuzzerPassInlineFunctions() = default;
33 
Apply()34 void FuzzerPassInlineFunctions::Apply() {
35   // |function_call_instructions| are the instructions that will be inlined.
36   // First, they will be collected and then do the inlining in another loop.
37   // This avoids changing the module while it is being inspected.
38   std::vector<opt::Instruction*> function_call_instructions;
39 
40   for (auto& function : *GetIRContext()->module()) {
41     for (auto& block : function) {
42       for (auto& instruction : block) {
43         if (!GetFuzzerContext()->ChoosePercentage(
44                 GetFuzzerContext()->GetChanceOfInliningFunction())) {
45           continue;
46         }
47 
48         // |instruction| must be suitable for inlining.
49         if (!TransformationInlineFunction::IsSuitableForInlining(
50                 GetIRContext(), &instruction)) {
51           continue;
52         }
53 
54         function_call_instructions.push_back(&instruction);
55       }
56     }
57   }
58 
59   // Once the function calls have been collected, it's time to actually create
60   // and apply the inlining transformations.
61   for (auto& function_call_instruction : function_call_instructions) {
62     // If |function_call_instruction| is not the penultimate instruction in its
63     // block or its block termination instruction is not OpBranch, then try to
64     // split |function_call_block| such that the conditions are met.
65     auto* function_call_block =
66         GetIRContext()->get_instr_block(function_call_instruction);
67     if ((function_call_instruction != &*--function_call_block->tail() ||
68          function_call_block->terminator()->opcode() != SpvOpBranch) &&
69         !MaybeApplyTransformation(TransformationSplitBlock(
70             MakeInstructionDescriptor(GetIRContext(),
71                                       function_call_instruction->NextNode()),
72             GetFuzzerContext()->GetFreshId()))) {
73       continue;
74     }
75 
76     auto* called_function = fuzzerutil::FindFunction(
77         GetIRContext(), function_call_instruction->GetSingleWordInOperand(0));
78 
79     // Mapping the called function instructions.
80     std::map<uint32_t, uint32_t> result_id_map;
81     for (auto& called_function_block : *called_function) {
82       // The called function entry block label will not be inlined.
83       if (&called_function_block != &*called_function->entry()) {
84         result_id_map[called_function_block.GetLabelInst()->result_id()] =
85             GetFuzzerContext()->GetFreshId();
86       }
87 
88       for (auto& instruction_to_inline : called_function_block) {
89         // The instructions are mapped to fresh ids.
90         if (instruction_to_inline.HasResultId()) {
91           result_id_map[instruction_to_inline.result_id()] =
92               GetFuzzerContext()->GetFreshId();
93         }
94       }
95     }
96 
97     // Applies the inline function transformation.
98     ApplyTransformation(TransformationInlineFunction(
99         function_call_instruction->result_id(), result_id_map));
100   }
101 }
102 
103 }  // namespace fuzz
104 }  // namespace spvtools
105