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/StringExtras.h"
15 #include "llvm/CodeGen/Passes.h"
16 #include "llvm/IR/Function.h"
17 #include "llvm/InitializePasses.h"
18 #include "llvm/MC/MCSymbol.h"
19 #include "llvm/Pass.h"
20 #include "llvm/Support/raw_ostream.h"
21 #include <cassert>
22 #include <memory>
23 #include <string>
24 
25 using namespace llvm;
26 
27 namespace {
28 
29 class Printer : public FunctionPass {
30   static char ID;
31 
32   raw_ostream &OS;
33 
34 public:
35   explicit Printer(raw_ostream &OS) : FunctionPass(ID), OS(OS) {}
36 
37   StringRef getPassName() const override;
38   void getAnalysisUsage(AnalysisUsage &AU) const override;
39 
40   bool runOnFunction(Function &F) override;
41   bool doFinalization(Module &M) override;
42 };
43 
44 } // end anonymous namespace
45 
46 INITIALIZE_PASS(GCModuleInfo, "collector-metadata",
47                 "Create Garbage Collector Module Metadata", false, false)
48 
49 // -----------------------------------------------------------------------------
50 
51 GCFunctionInfo::GCFunctionInfo(const Function &F, GCStrategy &S)
52     : F(F), S(S), FrameSize(~0LL) {}
53 
54 GCFunctionInfo::~GCFunctionInfo() = default;
55 
56 // -----------------------------------------------------------------------------
57 
58 char GCModuleInfo::ID = 0;
59 
60 GCModuleInfo::GCModuleInfo() : ImmutablePass(ID) {
61   initializeGCModuleInfoPass(*PassRegistry::getPassRegistry());
62 }
63 
64 GCFunctionInfo &GCModuleInfo::getFunctionInfo(const Function &F) {
65   assert(!F.isDeclaration() && "Can only get GCFunctionInfo for a definition!");
66   assert(F.hasGC());
67 
68   finfo_map_type::iterator I = FInfoMap.find(&F);
69   if (I != FInfoMap.end())
70     return *I->second;
71 
72   GCStrategy *S = getGCStrategy(F.getGC());
73   Functions.push_back(std::make_unique<GCFunctionInfo>(F, *S));
74   GCFunctionInfo *GFI = Functions.back().get();
75   FInfoMap[&F] = GFI;
76   return *GFI;
77 }
78 
79 void GCModuleInfo::clear() {
80   Functions.clear();
81   FInfoMap.clear();
82   GCStrategyList.clear();
83 }
84 
85 // -----------------------------------------------------------------------------
86 
87 char Printer::ID = 0;
88 
89 FunctionPass *llvm::createGCInfoPrinter(raw_ostream &OS) {
90   return new Printer(OS);
91 }
92 
93 StringRef Printer::getPassName() const {
94   return "Print Garbage Collector Information";
95 }
96 
97 void Printer::getAnalysisUsage(AnalysisUsage &AU) const {
98   FunctionPass::getAnalysisUsage(AU);
99   AU.setPreservesAll();
100   AU.addRequired<GCModuleInfo>();
101 }
102 
103 bool Printer::runOnFunction(Function &F) {
104   if (F.hasGC())
105     return false;
106 
107   GCFunctionInfo *FD = &getAnalysis<GCModuleInfo>().getFunctionInfo(F);
108 
109   OS << "GC roots for " << FD->getFunction().getName() << ":\n";
110   for (GCFunctionInfo::roots_iterator RI = FD->roots_begin(),
111                                       RE = FD->roots_end();
112        RI != RE; ++RI)
113     OS << "\t" << RI->Num << "\t" << RI->StackOffset << "[sp]\n";
114 
115   OS << "GC safe points for " << FD->getFunction().getName() << ":\n";
116   for (GCFunctionInfo::iterator PI = FD->begin(), PE = FD->end(); PI != PE;
117        ++PI) {
118 
119     OS << "\t" << PI->Label->getName() << ": " << "post-call"
120        << ", live = {";
121 
122     ListSeparator LS(",");
123     for (const GCRoot &R : make_range(FD->live_begin(PI), FD->live_end(PI)))
124       OS << LS << " " << R.Num;
125 
126     OS << " }\n";
127   }
128 
129   return false;
130 }
131 
132 bool Printer::doFinalization(Module &M) {
133   GCModuleInfo *GMI = getAnalysisIfAvailable<GCModuleInfo>();
134   assert(GMI && "Printer didn't require GCModuleInfo?!");
135   GMI->clear();
136   return false;
137 }
138 
139 GCStrategy *GCModuleInfo::getGCStrategy(const StringRef Name) {
140   // TODO: Arguably, just doing a linear search would be faster for small N
141   auto NMI = GCStrategyMap.find(Name);
142   if (NMI != GCStrategyMap.end())
143     return NMI->getValue();
144 
145   std::unique_ptr<GCStrategy> S = llvm::getGCStrategy(Name);
146   S->Name = std::string(Name);
147   GCStrategyMap[Name] = S.get();
148   GCStrategyList.push_back(std::move(S));
149   return GCStrategyList.back().get();
150 }
151