1 //===-- GCMetadata.cpp - Garbage collector metadata -----------------------===//
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 the GCFunctionInfo class and GCModuleInfo pass.
10 //
11 //===----------------------------------------------------------------------===//
12 
13 #include "llvm/CodeGen/GCMetadata.h"
14 #include "llvm/ADT/STLExtras.h"
15 #include "llvm/CodeGen/GCStrategy.h"
16 #include "llvm/CodeGen/Passes.h"
17 #include "llvm/IR/Function.h"
18 #include "llvm/InitializePasses.h"
19 #include "llvm/MC/MCSymbol.h"
20 #include "llvm/Pass.h"
21 #include "llvm/Support/ErrorHandling.h"
22 #include "llvm/Support/raw_ostream.h"
23 #include <algorithm>
24 #include <cassert>
25 #include <memory>
26 #include <string>
27 
28 using namespace llvm;
29 
30 namespace {
31 
32 class Printer : public FunctionPass {
33   static char ID;
34 
35   raw_ostream &OS;
36 
37 public:
38   explicit Printer(raw_ostream &OS) : FunctionPass(ID), OS(OS) {}
39 
40   StringRef getPassName() const override;
41   void getAnalysisUsage(AnalysisUsage &AU) const override;
42 
43   bool runOnFunction(Function &F) override;
44   bool doFinalization(Module &M) override;
45 };
46 
47 } // end anonymous namespace
48 
49 INITIALIZE_PASS(GCModuleInfo, "collector-metadata",
50                 "Create Garbage Collector Module Metadata", false, false)
51 
52 // -----------------------------------------------------------------------------
53 
54 GCFunctionInfo::GCFunctionInfo(const Function &F, GCStrategy &S)
55     : F(F), S(S), FrameSize(~0LL) {}
56 
57 GCFunctionInfo::~GCFunctionInfo() = default;
58 
59 // -----------------------------------------------------------------------------
60 
61 char GCModuleInfo::ID = 0;
62 
63 GCModuleInfo::GCModuleInfo() : ImmutablePass(ID) {
64   initializeGCModuleInfoPass(*PassRegistry::getPassRegistry());
65 }
66 
67 GCFunctionInfo &GCModuleInfo::getFunctionInfo(const Function &F) {
68   assert(!F.isDeclaration() && "Can only get GCFunctionInfo for a definition!");
69   assert(F.hasGC());
70 
71   finfo_map_type::iterator I = FInfoMap.find(&F);
72   if (I != FInfoMap.end())
73     return *I->second;
74 
75   GCStrategy *S = getGCStrategy(F.getGC());
76   Functions.push_back(std::make_unique<GCFunctionInfo>(F, *S));
77   GCFunctionInfo *GFI = Functions.back().get();
78   FInfoMap[&F] = GFI;
79   return *GFI;
80 }
81 
82 void GCModuleInfo::clear() {
83   Functions.clear();
84   FInfoMap.clear();
85   GCStrategyList.clear();
86 }
87 
88 // -----------------------------------------------------------------------------
89 
90 char Printer::ID = 0;
91 
92 FunctionPass *llvm::createGCInfoPrinter(raw_ostream &OS) {
93   return new Printer(OS);
94 }
95 
96 StringRef Printer::getPassName() const {
97   return "Print Garbage Collector Information";
98 }
99 
100 void Printer::getAnalysisUsage(AnalysisUsage &AU) const {
101   FunctionPass::getAnalysisUsage(AU);
102   AU.setPreservesAll();
103   AU.addRequired<GCModuleInfo>();
104 }
105 
106 bool Printer::runOnFunction(Function &F) {
107   if (F.hasGC())
108     return false;
109 
110   GCFunctionInfo *FD = &getAnalysis<GCModuleInfo>().getFunctionInfo(F);
111 
112   OS << "GC roots for " << FD->getFunction().getName() << ":\n";
113   for (GCFunctionInfo::roots_iterator RI = FD->roots_begin(),
114                                       RE = FD->roots_end();
115        RI != RE; ++RI)
116     OS << "\t" << RI->Num << "\t" << RI->StackOffset << "[sp]\n";
117 
118   OS << "GC safe points for " << FD->getFunction().getName() << ":\n";
119   for (GCFunctionInfo::iterator PI = FD->begin(), PE = FD->end(); PI != PE;
120        ++PI) {
121 
122     OS << "\t" << PI->Label->getName() << ": " << "post-call"
123        << ", live = {";
124 
125     for (GCFunctionInfo::live_iterator RI = FD->live_begin(PI),
126                                        RE = FD->live_end(PI);
127          ;) {
128       OS << " " << RI->Num;
129       if (++RI == RE)
130         break;
131       OS << ",";
132     }
133 
134     OS << " }\n";
135   }
136 
137   return false;
138 }
139 
140 bool Printer::doFinalization(Module &M) {
141   GCModuleInfo *GMI = getAnalysisIfAvailable<GCModuleInfo>();
142   assert(GMI && "Printer didn't require GCModuleInfo?!");
143   GMI->clear();
144   return false;
145 }
146 
147 GCStrategy *GCModuleInfo::getGCStrategy(const StringRef Name) {
148   // TODO: Arguably, just doing a linear search would be faster for small N
149   auto NMI = GCStrategyMap.find(Name);
150   if (NMI != GCStrategyMap.end())
151     return NMI->getValue();
152 
153   for (auto& Entry : GCRegistry::entries()) {
154     if (Name == Entry.getName()) {
155       std::unique_ptr<GCStrategy> S = Entry.instantiate();
156       S->Name = Name;
157       GCStrategyMap[Name] = S.get();
158       GCStrategyList.push_back(std::move(S));
159       return GCStrategyList.back().get();
160     }
161   }
162 
163   if (GCRegistry::begin() == GCRegistry::end()) {
164     // In normal operation, the registry should not be empty.  There should
165     // be the builtin GCs if nothing else.  The most likely scenario here is
166     // that we got here without running the initializers used by the Registry
167     // itself and it's registration mechanism.
168     const std::string error = ("unsupported GC: " + Name).str() +
169       " (did you remember to link and initialize the CodeGen library?)";
170     report_fatal_error(error);
171   } else
172     report_fatal_error(std::string("unsupported GC: ") + Name);
173 }
174