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/transformation_adjust_branch_weights.h"
16
17 #include "source/fuzz/fuzzer_util.h"
18 #include "source/fuzz/instruction_descriptor.h"
19
20 namespace spvtools {
21 namespace fuzz {
22
23 namespace {
24
25 const uint32_t kBranchWeightForTrueLabelIndex = 3;
26 const uint32_t kBranchWeightForFalseLabelIndex = 4;
27
28 } // namespace
29
TransformationAdjustBranchWeights(const spvtools::fuzz::protobufs::TransformationAdjustBranchWeights & message)30 TransformationAdjustBranchWeights::TransformationAdjustBranchWeights(
31 const spvtools::fuzz::protobufs::TransformationAdjustBranchWeights& message)
32 : message_(message) {}
33
TransformationAdjustBranchWeights(const protobufs::InstructionDescriptor & instruction_descriptor,const std::pair<uint32_t,uint32_t> & branch_weights)34 TransformationAdjustBranchWeights::TransformationAdjustBranchWeights(
35 const protobufs::InstructionDescriptor& instruction_descriptor,
36 const std::pair<uint32_t, uint32_t>& branch_weights) {
37 *message_.mutable_instruction_descriptor() = instruction_descriptor;
38 message_.mutable_branch_weights()->set_first(branch_weights.first);
39 message_.mutable_branch_weights()->set_second(branch_weights.second);
40 }
41
IsApplicable(opt::IRContext * ir_context,const TransformationContext &) const42 bool TransformationAdjustBranchWeights::IsApplicable(
43 opt::IRContext* ir_context, const TransformationContext& /*unused*/) const {
44 auto instruction =
45 FindInstruction(message_.instruction_descriptor(), ir_context);
46 if (instruction == nullptr) {
47 return false;
48 }
49
50 SpvOp opcode = static_cast<SpvOp>(
51 message_.instruction_descriptor().target_instruction_opcode());
52
53 assert(instruction->opcode() == opcode &&
54 "The located instruction must have the same opcode as in the "
55 "descriptor.");
56
57 // Must be an OpBranchConditional instruction.
58 if (opcode != SpvOpBranchConditional) {
59 return false;
60 }
61
62 assert((message_.branch_weights().first() != 0 ||
63 message_.branch_weights().second() != 0) &&
64 "At least one weight must be non-zero.");
65
66 assert(message_.branch_weights().first() <=
67 UINT32_MAX - message_.branch_weights().second() &&
68 "The sum of the two weights must not be greater than UINT32_MAX.");
69
70 return true;
71 }
72
Apply(opt::IRContext * ir_context,TransformationContext *) const73 void TransformationAdjustBranchWeights::Apply(
74 opt::IRContext* ir_context, TransformationContext* /*unused*/) const {
75 auto instruction =
76 FindInstruction(message_.instruction_descriptor(), ir_context);
77 if (instruction->HasBranchWeights()) {
78 instruction->SetOperand(kBranchWeightForTrueLabelIndex,
79 {message_.branch_weights().first()});
80 instruction->SetOperand(kBranchWeightForFalseLabelIndex,
81 {message_.branch_weights().second()});
82 } else {
83 instruction->AddOperand({SPV_OPERAND_TYPE_OPTIONAL_LITERAL_INTEGER,
84 {message_.branch_weights().first()}});
85 instruction->AddOperand({SPV_OPERAND_TYPE_OPTIONAL_LITERAL_INTEGER,
86 {message_.branch_weights().second()}});
87 }
88 }
89
ToMessage() const90 protobufs::Transformation TransformationAdjustBranchWeights::ToMessage() const {
91 protobufs::Transformation result;
92 *result.mutable_adjust_branch_weights() = message_;
93 return result;
94 }
95
GetFreshIds() const96 std::unordered_set<uint32_t> TransformationAdjustBranchWeights::GetFreshIds()
97 const {
98 return std::unordered_set<uint32_t>();
99 }
100
101 } // namespace fuzz
102 } // namespace spvtools
103