1 //===- ReduceMetadata.cpp - Specialized Delta Pass ------------------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements two functions used by the Generic Delta Debugging
10 // Algorithm, which are used to reduce Metadata nodes.
11 //
12 //===----------------------------------------------------------------------===//
13 
14 #include "ReduceMetadata.h"
15 #include "Delta.h"
16 #include "llvm/ADT/Sequence.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/IR/InstIterator.h"
19 #include <vector>
20 
21 using namespace llvm;
22 
23 /// Removes all the Named and Unnamed Metadata Nodes, as well as any debug
24 /// functions that aren't inside the desired Chunks.
25 static void extractMetadataFromModule(const std::vector<Chunk> &ChunksToKeep,
26                                       Module *Program) {
27   Oracle O(ChunksToKeep);
28 
29   // Get out-of-chunk Named metadata nodes
30   SmallVector<NamedMDNode *> NamedNodesToDelete;
31   for (NamedMDNode &MD : Program->named_metadata())
32     if (!O.shouldKeep())
33       NamedNodesToDelete.push_back(&MD);
34 
35   for (NamedMDNode *NN : NamedNodesToDelete) {
36     for (auto I : seq<unsigned>(0, NN->getNumOperands()))
37       NN->setOperand(I, NULL);
38     NN->eraseFromParent();
39   }
40 
41   // Delete out-of-chunk metadata attached to globals.
42   SmallVector<std::pair<unsigned, MDNode *>> MDs;
43   for (GlobalVariable &GV : Program->globals()) {
44     GV.getAllMetadata(MDs);
45     for (std::pair<unsigned, MDNode *> &MD : MDs)
46       if (!O.shouldKeep())
47         GV.setMetadata(MD.first, NULL);
48   }
49 
50   for (Function &F : *Program) {
51     // Delete out-of-chunk metadata attached to functions.
52     F.getAllMetadata(MDs);
53     for (std::pair<unsigned, MDNode *> &MD : MDs)
54       if (!O.shouldKeep())
55         F.setMetadata(MD.first, NULL);
56 
57     // Delete out-of-chunk metadata attached to instructions.
58     for (Instruction &I : instructions(F)) {
59       I.getAllMetadata(MDs);
60       for (std::pair<unsigned, MDNode *> &MD : MDs)
61         if (!O.shouldKeep())
62           I.setMetadata(MD.first, NULL);
63     }
64   }
65 }
66 
67 static int countMetadataTargets(Module *Program) {
68   int NamedMetadataNodes = Program->named_metadata_size();
69 
70   // Get metadata attached to globals.
71   int GlobalMetadataArgs = 0;
72   SmallVector<std::pair<unsigned, MDNode *>> MDs;
73   for (GlobalVariable &GV : Program->globals()) {
74     GV.getAllMetadata(MDs);
75     GlobalMetadataArgs += MDs.size();
76   }
77 
78   // Get metadata attached to functions & instructions.
79   int FunctionMetadataArgs = 0;
80   int InstructionMetadataArgs = 0;
81   for (Function &F : *Program) {
82     F.getAllMetadata(MDs);
83     FunctionMetadataArgs += MDs.size();
84 
85     for (Instruction &I : instructions(F)) {
86       I.getAllMetadata(MDs);
87       InstructionMetadataArgs += MDs.size();
88     }
89   }
90 
91   return NamedMetadataNodes + GlobalMetadataArgs + FunctionMetadataArgs +
92          InstructionMetadataArgs;
93 }
94 
95 void llvm::reduceMetadataDeltaPass(TestRunner &Test) {
96   outs() << "*** Reducing Metadata...\n";
97   int MDCount = countMetadataTargets(Test.getProgram());
98   runDeltaPass(Test, MDCount, extractMetadataFromModule);
99   outs() << "----------------------------\n";
100 }
101