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(Oracle &O, Module &Program) {
26   // Get out-of-chunk Named metadata nodes
27   SmallVector<NamedMDNode *> NamedNodesToDelete;
28   for (NamedMDNode &MD : Program.named_metadata())
29     if (!O.shouldKeep())
30       NamedNodesToDelete.push_back(&MD);
31 
32   for (NamedMDNode *NN : NamedNodesToDelete) {
33     for (auto I : seq<unsigned>(0, NN->getNumOperands()))
34       NN->setOperand(I, nullptr);
35     NN->eraseFromParent();
36   }
37 
38   // Delete out-of-chunk metadata attached to globals.
39   for (GlobalVariable &GV : Program.globals()) {
40     SmallVector<std::pair<unsigned, MDNode *>> MDs;
41     GV.getAllMetadata(MDs);
42     for (std::pair<unsigned, MDNode *> &MD : MDs)
43       if (!O.shouldKeep())
44         GV.setMetadata(MD.first, nullptr);
45   }
46 
47   for (Function &F : Program) {
48     {
49       SmallVector<std::pair<unsigned, MDNode *>> MDs;
50       // Delete out-of-chunk metadata attached to functions.
51       F.getAllMetadata(MDs);
52       for (std::pair<unsigned, MDNode *> &MD : MDs)
53         if (!O.shouldKeep())
54           F.setMetadata(MD.first, nullptr);
55     }
56 
57     // Delete out-of-chunk metadata attached to instructions.
58     for (Instruction &I : instructions(F)) {
59       SmallVector<std::pair<unsigned, MDNode *>> MDs;
60       I.getAllMetadata(MDs);
61       for (std::pair<unsigned, MDNode *> &MD : MDs)
62         if (!O.shouldKeep())
63           I.setMetadata(MD.first, nullptr);
64     }
65   }
66 }
67 
68 void llvm::reduceMetadataDeltaPass(TestRunner &Test) {
69   outs() << "*** Reducing Metadata...\n";
70   runDeltaPass(Test, extractMetadataFromModule);
71   outs() << "----------------------------\n";
72 }
73