GCMetadata.cpp

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//===-- GCMetadata.cpp - Garbage collector metadata -----------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// This file implements the GCFunctionInfo class and GCModuleInfo pass.
//
//===----------------------------------------------------------------------===//
 
#include "llvm/CodeGen/GCMetadata.h"
#include "llvm/ADT/StringExtras.h"
#include "llvm/CodeGen/Passes.h"
#include "llvm/IR/Function.h"
#include "llvm/InitializePasses.h"
#include "llvm/MC/MCSymbol.h"
#include "llvm/Pass.h"
#include "llvm/Support/raw_ostream.h"
#include <cassert>
#include <memory>
#include <string>
 
using namespace llvm;
 
namespace {
 
class Printer : public FunctionPass {
  static char ID;
 
  raw_ostream &OS;
 
public:
  explicit Printer(raw_ostream &OS) : FunctionPass(ID), OS(OS) {}
 
  StringRef getPassName() const override;
  void getAnalysisUsage(AnalysisUsage &AU) const override;
 
  bool runOnFunction(Function &F) override;
  bool doFinalization(Module &M) override;
};
 
} // end anonymous namespace
 
INITIALIZE_PASS(GCModuleInfo, "collector-metadata",
                "Create Garbage Collector Module Metadata", false, false)
 
// -----------------------------------------------------------------------------
 
GCFunctionInfo::GCFunctionInfo(const Function &F, GCStrategy &S)
    : F(F), S(S), FrameSize(~0LL) {}
 
GCFunctionInfo::~GCFunctionInfo() = default;
 
// -----------------------------------------------------------------------------
 
char GCModuleInfo::ID = 0;
 
GCModuleInfo::GCModuleInfo() : ImmutablePass(ID) {
  initializeGCModuleInfoPass(*PassRegistry::getPassRegistry());
}
 
GCFunctionInfo &GCModuleInfo::getFunctionInfo(const Function &F) {
  assert(!F.isDeclaration() && "Can only get GCFunctionInfo for a definition!");
  assert(F.hasGC());
 
  finfo_map_type::iterator I = FInfoMap.find(&F);
  if (I != FInfoMap.end())
    return *I->second;
 
  GCStrategy *S = getGCStrategy(F.getGC());
  Functions.push_back(std::make_unique<GCFunctionInfo>(F, *S));
  GCFunctionInfo *GFI = Functions.back().get();
  FInfoMap[&F] = GFI;
  return *GFI;
}
 
void GCModuleInfo::clear() {
  Functions.clear();
  FInfoMap.clear();
  GCStrategyList.clear();
}
 
// -----------------------------------------------------------------------------
 
char Printer::ID = 0;
 
FunctionPass *llvm::createGCInfoPrinter(raw_ostream &OS) {
  return new Printer(OS);
}
 
StringRef Printer::getPassName() const {
  return "Print Garbage Collector Information";
}
 
void Printer::getAnalysisUsage(AnalysisUsage &AU) const {
  FunctionPass::getAnalysisUsage(AU);
  AU.setPreservesAll();
  AU.addRequired<GCModuleInfo>();
}
 
bool Printer::runOnFunction(Function &F) {
  if (F.hasGC())
    return false;
 
  GCFunctionInfo *FD = &getAnalysis<GCModuleInfo>().getFunctionInfo(F);
 
  OS << "GC roots for " << FD->getFunction().getName() << ":\n";
  for (GCFunctionInfo::roots_iterator RI = FD->roots_begin(),
                                      RE = FD->roots_end();
       RI != RE; ++RI)
    OS << "\t" << RI->Num << "\t" << RI->StackOffset << "[sp]\n";
 
  OS << "GC safe points for " << FD->getFunction().getName() << ":\n";
  for (GCFunctionInfo::iterator PI = FD->begin(), PE = FD->end(); PI != PE;
       ++PI) {
 
    OS << "\t" << PI->Label->getName() << ": " << "post-call"
       << ", live = {";
 
    ListSeparator LS(",");
    for (const GCRoot &R : make_range(FD->live_begin(PI), FD->live_end(PI)))
      OS << LS << " " << R.Num;
 
    OS << " }\n";
  }
 
  return false;
}
 
bool Printer::doFinalization(Module &M) {
  GCModuleInfo *GMI = getAnalysisIfAvailable<GCModuleInfo>();
  assert(GMI && "Printer didn't require GCModuleInfo?!");
  GMI->clear();
  return false;
}
 
GCStrategy *GCModuleInfo::getGCStrategy(const StringRef Name) {
  // TODO: Arguably, just doing a linear search would be faster for small N
  auto NMI = GCStrategyMap.find(Name);
  if (NMI != GCStrategyMap.end())
    return NMI->getValue();
 
  std::unique_ptr<GCStrategy> S = llvm::getGCStrategy(Name);
  S->Name = std::string(Name);
  GCStrategyMap[Name] = S.get();
  GCStrategyList.push_back(std::move(S));
  return GCStrategyList.back().get();
}