1 //===- ReduceDIMetadata.cpp - Specialized Delta pass for DebugInfo --------===//
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 DebugInfo metadata nodes.
11 //
12 //===----------------------------------------------------------------------===//
13
14 #include "ReduceDIMetadata.h"
15 #include "Delta.h"
16 #include "llvm/ADT/Sequence.h"
17 #include "llvm/ADT/SetVector.h"
18 #include "llvm/ADT/SmallVector.h"
19 #include "llvm/IR/DebugInfoMetadata.h"
20 #include "llvm/IR/InstIterator.h"
21 #include <tuple>
22 #include <vector>
23
24 using namespace llvm;
25
26 using MDNodeList = SmallVector<MDNode *>;
27
identifyUninterestingMDNodes(Oracle & O,MDNodeList & MDs)28 void identifyUninterestingMDNodes(Oracle &O, MDNodeList &MDs) {
29 SetVector<std::tuple<MDNode *, size_t, MDNode *>> Tuples;
30 std::vector<MDNode *> ToLook;
31 SetVector<MDNode *> Visited;
32
33 // Start by looking at the attachments we collected
34 for (const auto &NMD : MDs)
35 if (NMD)
36 ToLook.push_back(NMD);
37
38 while (!ToLook.empty()) {
39 MDNode *MD = ToLook.back();
40 ToLook.pop_back();
41
42 if (Visited.count(MD))
43 continue;
44
45 // Determine if the current MDNode is DebugInfo
46 if (DINode *DIM = dyn_cast_or_null<DINode>(MD)) {
47 // Scan operands and record attached tuples
48 for (size_t I = 0; I < DIM->getNumOperands(); ++I)
49 if (MDTuple *MDT = dyn_cast_or_null<MDTuple>(DIM->getOperand(I)))
50 if (!Visited.count(MDT) && MDT->getNumOperands())
51 Tuples.insert({DIM, I, MDT});
52 }
53
54 // Add all of the operands of the current node to the loop's todo list.
55 for (Metadata *Op : MD->operands())
56 if (MDNode *OMD = dyn_cast_or_null<MDNode>(Op))
57 ToLook.push_back(OMD);
58
59 Visited.insert(MD);
60 }
61
62 for (auto &T : Tuples) {
63 auto [DbgNode, OpIdx, Tup] = T;
64 // Remove the operands of the tuple that are not in the desired chunks.
65 SmallVector<Metadata *, 16> TN;
66 for (size_t I = 0; I < Tup->getNumOperands(); ++I) {
67 // Ignore any operands that are not DebugInfo metadata nodes.
68 if (Metadata *Op = Tup->getOperand(I).get()) {
69 if (isa<DINode>(Op) || isa<DIGlobalVariableExpression>(Op))
70 // Don't add uninteresting operands to the tuple.
71 if (!O.shouldKeep())
72 continue;
73 TN.push_back(Op);
74 }
75 }
76 if (TN.size() != Tup->getNumOperands())
77 DbgNode->replaceOperandWith(OpIdx, DbgNode->get(DbgNode->getContext(), TN));
78 }
79 }
80
extractDIMetadataFromModule(Oracle & O,ReducerWorkItem & WorkItem)81 static void extractDIMetadataFromModule(Oracle &O, ReducerWorkItem &WorkItem) {
82 Module &Program = WorkItem.getModule();
83
84 MDNodeList MDs;
85 // Collect all !dbg metadata attachments.
86 for (const auto &DC : Program.debug_compile_units())
87 if (DC)
88 MDs.push_back(DC);
89 for (GlobalVariable &GV : Program.globals())
90 GV.getMetadata(llvm::LLVMContext::MD_dbg, MDs);
91 for (Function &F : Program.functions()) {
92 F.getMetadata(llvm::LLVMContext::MD_dbg, MDs);
93 for (Instruction &I : instructions(F))
94 if (auto *DI = I.getMetadata(llvm::LLVMContext::MD_dbg))
95 MDs.push_back(DI);
96 }
97 identifyUninterestingMDNodes(O, MDs);
98 }
99
reduceDIMetadataDeltaPass(TestRunner & Test)100 void llvm::reduceDIMetadataDeltaPass(TestRunner &Test) {
101 runDeltaPass(Test, extractDIMetadataFromModule, "Reducing DIMetadata");
102 }
103