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_FUZZER_PASS_OUTLINE_FUNCTIONS_H_
16 #define SOURCE_FUZZ_FUZZER_PASS_OUTLINE_FUNCTIONS_H_
17 
18 #include "source/fuzz/fuzzer_pass.h"
19 
20 namespace spvtools {
21 namespace fuzz {
22 
23 // A fuzzer pass for outlining single-entry single-exit regions of a  control
24 // flow graph into their own functions.
25 class FuzzerPassOutlineFunctions : public FuzzerPass {
26  public:
27   FuzzerPassOutlineFunctions(
28       opt::IRContext* ir_context, TransformationContext* transformation_context,
29       FuzzerContext* fuzzer_context,
30       protobufs::TransformationSequence* transformations);
31 
32   ~FuzzerPassOutlineFunctions();
33 
34   void Apply() override;
35 
36   // Returns a block suitable to be an entry block for a region that can be
37   // outlined, i.e. a block that is not a loop header and that does not start
38   // with OpPhi or OpVariable. In particular, it returns:
39   // - |entry_block| if it is suitable
40   // - otherwise, a block found by:
41   //   - looking for or creating a new preheader, if |entry_block| is a loop
42   //     header
43   //   - splitting the candidate entry block, if it starts with OpPhi or
44   //     OpVariable.
45   // Returns nullptr if a suitable block cannot be found following the
46   // instructions above.
47   opt::BasicBlock* MaybeGetEntryBlockSuitableForOutlining(
48       opt::BasicBlock* entry_block);
49 
50   // Returns:
51   // - |exit_block| if it is not a merge block
52   // - the second block obtained by splitting |exit_block|, if |exit_block| is a
53   //   merge block.
54   // Assumes that |exit_block| is not a continue target.
55   // The block returned by this function should be suitable to be the exit block
56   // of a region that can be outlined.
57   // Returns nullptr if |exit_block| is a merge block and it cannot be split.
58   opt::BasicBlock* MaybeGetExitBlockSuitableForOutlining(
59       opt::BasicBlock* exit_block);
60 };
61 
62 }  // namespace fuzz
63 }  // namespace spvtools
64 
65 #endif  // SOURCE_FUZZ_FUZZER_PASS_OUTLINE_FUNCTIONS_H_
66