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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 #ifndef SOURCE_FUZZ_SHRINKER_H_
16 #define SOURCE_FUZZ_SHRINKER_H_
17 
18 #include <memory>
19 #include <vector>
20 
21 #include "source/fuzz/protobufs/spirvfuzz_protobufs.h"
22 #include "spirv-tools/libspirv.hpp"
23 
24 namespace spvtools {
25 namespace fuzz {
26 
27 // Shrinks a sequence of transformations that lead to an interesting SPIR-V
28 // binary to yield a smaller sequence of transformations that still produce an
29 // interesting binary.
30 class Shrinker {
31  public:
32   // Possible statuses that can result from running the shrinker.
33   enum class ShrinkerResultStatus {
34     kComplete,
35     kFailedToCreateSpirvToolsInterface,
36     kInitialBinaryInvalid,
37     kInitialBinaryNotInteresting,
38     kReplayFailed,
39     kStepLimitReached,
40     kAddedFunctionReductionFailed,
41   };
42 
43   struct ShrinkerResult {
44     ShrinkerResultStatus status;
45     std::vector<uint32_t> transformed_binary;
46     protobufs::TransformationSequence applied_transformations;
47   };
48 
49   // The type for a function that will take a binary, |binary|, and return true
50   // if and only if the binary is deemed interesting. (The function also takes
51   // an integer argument, |counter|, that will be incremented each time the
52   // function is called; this is for debugging purposes).
53   //
54   // The notion of "interesting" depends on what properties of the binary or
55   // tools that process the binary we are trying to maintain during shrinking.
56   using InterestingnessFunction = std::function<bool(
57       const std::vector<uint32_t>& binary, uint32_t counter)>;
58 
59   Shrinker(spv_target_env target_env, MessageConsumer consumer,
60            const std::vector<uint32_t>& binary_in,
61            const protobufs::FactSequence& initial_facts,
62            const protobufs::TransformationSequence& transformation_sequence_in,
63            const InterestingnessFunction& interestingness_function,
64            uint32_t step_limit, bool validate_during_replay,
65            spv_validator_options validator_options);
66 
67   // Disables copy/move constructor/assignment operations.
68   Shrinker(const Shrinker&) = delete;
69   Shrinker(Shrinker&&) = delete;
70   Shrinker& operator=(const Shrinker&) = delete;
71   Shrinker& operator=(Shrinker&&) = delete;
72 
73   ~Shrinker();
74 
75   // Requires that when |transformation_sequence_in_| is applied to |binary_in_|
76   // with initial facts |initial_facts_|, the resulting binary is interesting
77   // according to |interestingness_function_|.
78   //
79   // If shrinking succeeded -- possibly terminating early due to reaching the
80   // shrinker's step limit -- an associated result status is returned together
81   // with a subsequence of |transformation_sequence_in_| that, when applied
82   // to |binary_in_| with initial facts |initial_facts_|, produces a binary
83   // that is also interesting according to |interestingness_function_|; this
84   // binary is also returned.
85   //
86   // If shrinking failed for some reason, an appropriate result status is
87   // returned together with an empty binary and empty transformation sequence.
88   ShrinkerResult Run();
89 
90  private:
91   // Returns the id bound for the given SPIR-V binary, which is assumed to be
92   // valid.
93   uint32_t GetIdBound(const std::vector<uint32_t>& binary) const;
94 
95   // Target environment.
96   const spv_target_env target_env_;
97 
98   // Message consumer that will be invoked once for each message communicated
99   // from the library.
100   MessageConsumer consumer_;
101 
102   // The binary to which transformations are to be applied.
103   const std::vector<uint32_t>& binary_in_;
104 
105   // Initial facts known to hold in advance of applying any transformations.
106   const protobufs::FactSequence& initial_facts_;
107 
108   // The series of transformations to be shrunk.
109   const protobufs::TransformationSequence& transformation_sequence_in_;
110 
111   // Function that decides whether a given module is interesting.
112   const InterestingnessFunction& interestingness_function_;
113 
114   // Step limit to decide when to terminate shrinking early.
115   const uint32_t step_limit_;
116 
117   // Determines whether to check for validity during the replaying of
118   // transformations.
119   const bool validate_during_replay_;
120 
121   // Options to control validation.
122   spv_validator_options validator_options_;
123 };
124 
125 }  // namespace fuzz
126 }  // namespace spvtools
127 
128 #endif  // SOURCE_FUZZ_SHRINKER_H_
129