1 //===----- llvm/CodeGen/GlobalISel/LostDebugLocObserver.cpp -----*- C++ -*-===//
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 /// Tracks DebugLocs between checkpoints and verifies that they are transferred.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/CodeGen/GlobalISel/LostDebugLocObserver.h"
14 
15 using namespace llvm;
16 
17 #define LOC_DEBUG(X) DEBUG_WITH_TYPE(DebugType.str().c_str(), X)
18 
19 void LostDebugLocObserver::analyzeDebugLocations() {
20   if (LostDebugLocs.empty()) {
21     LOC_DEBUG(dbgs() << ".. No debug info was present\n");
22     return;
23   }
24   if (PotentialMIsForDebugLocs.empty()) {
25     LOC_DEBUG(
26         dbgs() << ".. No instructions to carry debug info (dead code?)\n");
27     return;
28   }
29 
30   LOC_DEBUG(dbgs() << ".. Searching " << PotentialMIsForDebugLocs.size()
31                    << " instrs for " << LostDebugLocs.size() << " locations\n");
32   SmallPtrSet<MachineInstr *, 4> FoundIn;
33   for (MachineInstr *MI : PotentialMIsForDebugLocs) {
34     if (!MI->getDebugLoc())
35       continue;
36     // Check this first in case there's a matching line-0 location on both input
37     // and output.
38     if (MI->getDebugLoc().getLine() == 0) {
39       LOC_DEBUG(
40           dbgs() << ".. Assuming line-0 location covers remainder (if any)\n");
41       return;
42     }
43     if (LostDebugLocs.erase(MI->getDebugLoc())) {
44       LOC_DEBUG(dbgs() << ".. .. found " << MI->getDebugLoc() << " in " << *MI);
45       FoundIn.insert(MI);
46       continue;
47     }
48   }
49   if (LostDebugLocs.empty())
50     return;
51 
52   NumLostDebugLocs += LostDebugLocs.size();
53   LOC_DEBUG({
54     dbgs() << ".. Lost locations:\n";
55     for (const DebugLoc &Loc : LostDebugLocs) {
56       dbgs() << ".. .. ";
57       Loc.print(dbgs());
58       dbgs() << "\n";
59     }
60     dbgs() << ".. MIs with matched locations:\n";
61     for (MachineInstr *MI : FoundIn)
62       if (PotentialMIsForDebugLocs.erase(MI))
63         dbgs() << ".. .. " << *MI;
64     dbgs() << ".. Remaining MIs with unmatched/no locations:\n";
65     for (const MachineInstr *MI : PotentialMIsForDebugLocs)
66       dbgs() << ".. .. " << *MI;
67   });
68 }
69 
70 void LostDebugLocObserver::checkpoint(bool CheckDebugLocs) {
71   if (CheckDebugLocs)
72     analyzeDebugLocations();
73   PotentialMIsForDebugLocs.clear();
74   LostDebugLocs.clear();
75 }
76 
77 void LostDebugLocObserver::createdInstr(MachineInstr &MI) {
78   PotentialMIsForDebugLocs.insert(&MI);
79 }
80 
81 static bool irTranslatorNeverAddsLocations(unsigned Opcode) {
82   switch (Opcode) {
83   default:
84     return false;
85   case TargetOpcode::G_CONSTANT:
86   case TargetOpcode::G_FCONSTANT:
87   case TargetOpcode::G_IMPLICIT_DEF:
88   case TargetOpcode::G_GLOBAL_VALUE:
89     return true;
90   }
91 }
92 
93 void LostDebugLocObserver::erasingInstr(MachineInstr &MI) {
94   if (irTranslatorNeverAddsLocations(MI.getOpcode()))
95     return;
96 
97   PotentialMIsForDebugLocs.erase(&MI);
98   if (MI.getDebugLoc())
99     LostDebugLocs.insert(MI.getDebugLoc());
100 }
101 
102 void LostDebugLocObserver::changingInstr(MachineInstr &MI) {
103   if (irTranslatorNeverAddsLocations(MI.getOpcode()))
104     return;
105 
106   PotentialMIsForDebugLocs.erase(&MI);
107   if (MI.getDebugLoc())
108     LostDebugLocs.insert(MI.getDebugLoc());
109 }
110 
111 void LostDebugLocObserver::changedInstr(MachineInstr &MI) {
112   PotentialMIsForDebugLocs.insert(&MI);
113 }
114