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/fuzz/instruction_descriptor.h"
16
17 namespace spvtools {
18 namespace fuzz {
19
FindInstruction(const protobufs::InstructionDescriptor & instruction_descriptor,spvtools::opt::IRContext * context)20 opt::Instruction* FindInstruction(
21 const protobufs::InstructionDescriptor& instruction_descriptor,
22 spvtools::opt::IRContext* context) {
23 for (auto& function : *context->module()) {
24 for (auto& block : function) {
25 bool found_base =
26 block.id() == instruction_descriptor.base_instruction_result_id();
27 uint32_t num_ignored = 0;
28 for (auto& instruction : block) {
29 if (instruction.HasResultId() &&
30 instruction.result_id() ==
31 instruction_descriptor.base_instruction_result_id()) {
32 assert(!found_base &&
33 "It should not be possible to find the base instruction "
34 "multiple times.");
35 found_base = true;
36 assert(num_ignored == 0 &&
37 "The skipped instruction count should only be incremented "
38 "after the instruction base has been found.");
39 }
40 if (found_base &&
41 instruction.opcode() ==
42 instruction_descriptor.target_instruction_opcode()) {
43 if (num_ignored == instruction_descriptor.num_opcodes_to_ignore()) {
44 return &instruction;
45 }
46 num_ignored++;
47 }
48 }
49 if (found_base) {
50 // We found the base instruction, but did not find the target
51 // instruction in the same block.
52 return nullptr;
53 }
54 }
55 }
56 return nullptr;
57 }
58
MakeInstructionDescriptor(uint32_t base_instruction_result_id,SpvOp target_instruction_opcode,uint32_t num_opcodes_to_ignore)59 protobufs::InstructionDescriptor MakeInstructionDescriptor(
60 uint32_t base_instruction_result_id, SpvOp target_instruction_opcode,
61 uint32_t num_opcodes_to_ignore) {
62 protobufs::InstructionDescriptor result;
63 result.set_base_instruction_result_id(base_instruction_result_id);
64 result.set_target_instruction_opcode(target_instruction_opcode);
65 result.set_num_opcodes_to_ignore(num_opcodes_to_ignore);
66 return result;
67 }
68
MakeInstructionDescriptor(const opt::BasicBlock & block,const opt::BasicBlock::const_iterator & inst_it)69 protobufs::InstructionDescriptor MakeInstructionDescriptor(
70 const opt::BasicBlock& block,
71 const opt::BasicBlock::const_iterator& inst_it) {
72 const SpvOp opcode =
73 inst_it->opcode(); // The opcode of the instruction being described.
74 uint32_t skip_count = 0; // The number of these opcodes we have skipped when
75 // searching backwards.
76
77 // Consider instructions in the block in reverse order, starting from
78 // |inst_it|.
79 for (opt::BasicBlock::const_iterator backwards_iterator = inst_it;;
80 --backwards_iterator) {
81 if (backwards_iterator->HasResultId()) {
82 // As soon as we find an instruction with a result id, we can return a
83 // descriptor for |inst_it|.
84 return MakeInstructionDescriptor(backwards_iterator->result_id(), opcode,
85 skip_count);
86 }
87 if (backwards_iterator != inst_it &&
88 backwards_iterator->opcode() == opcode) {
89 // We are skipping over an instruction with the same opcode as |inst_it|;
90 // we increase our skip count to reflect this.
91 skip_count++;
92 }
93 if (backwards_iterator == block.begin()) {
94 // We exit the loop when we reach the start of the block, but only after
95 // we have processed the first instruction in the block.
96 break;
97 }
98 }
99 // We did not find an instruction inside the block with a result id, so we use
100 // the block's label's id.
101 return MakeInstructionDescriptor(block.id(), opcode, skip_count);
102 }
103
MakeInstructionDescriptor(opt::IRContext * context,opt::Instruction * inst)104 protobufs::InstructionDescriptor MakeInstructionDescriptor(
105 opt::IRContext* context, opt::Instruction* inst) {
106 auto block = context->get_instr_block(inst);
107 uint32_t base_instruction_result_id = block->id();
108 uint32_t num_opcodes_to_ignore = 0;
109 for (auto& inst_in_block : *block) {
110 if (inst_in_block.HasResultId()) {
111 base_instruction_result_id = inst_in_block.result_id();
112 num_opcodes_to_ignore = 0;
113 }
114 if (&inst_in_block == inst) {
115 return MakeInstructionDescriptor(base_instruction_result_id,
116 inst->opcode(), num_opcodes_to_ignore);
117 }
118 if (inst_in_block.opcode() == inst->opcode()) {
119 num_opcodes_to_ignore++;
120 }
121 }
122 assert(false && "No matching instruction was found.");
123 return protobufs::InstructionDescriptor();
124 }
125
126 } // namespace fuzz
127 } // namespace spvtools
128