[CodeGen][GC] Remove GCInfoPrinter (#75033)

This pass is broken and looks like no one uses it for the last 15+ years.

```c++
bool Printer::runOnFunction(Function &F) {
  if (F.hasGC())
    return false;

  GCFunctionInfo *FD = &getAnalysis<GCModuleInfo>().getFunctionInfo(F);
```
```c++
GCFunctionInfo &GCModuleInfo::getFunctionInfo(const Function &F) {
  assert(!F.isDeclaration() && "Can only get GCFunctionInfo for a definition!");
  assert(F.hasGC()); // Equivalent to `assert(false);` when called by `Printer::runOnFunction`
```

See also #74972.

Author: paperchalice

llvm/include/llvm/CodeGen/MachinePassRegistry.def

@@ -126,7 +126,6 @@ DUMMY_FUNCTION_PASS("cfguard-check", CFGuardCheckPass, ())
 DUMMY_FUNCTION_PASS("cfguard-dispatch", CFGuardDispatchPass, ())
 DUMMY_FUNCTION_PASS("codegenprepare", CodeGenPreparePass, ())
 DUMMY_FUNCTION_PASS("expandmemcmp", ExpandMemCmpPass, ())
-DUMMY_FUNCTION_PASS("gc-info-printer", GCInfoPrinterPass, ())
 DUMMY_FUNCTION_PASS("gc-lowering", GCLoweringPass, ())
 DUMMY_FUNCTION_PASS("indirectbr-expand", IndirectBrExpandPass, ())
 DUMMY_FUNCTION_PASS("select-optimize", SelectOptimizePass, ())

llvm/include/llvm/CodeGen/Passes.h

@@ -324,10 +324,6 @@ namespace llvm {
   /// branch folding).
   extern char &GCMachineCodeAnalysisID;
 
-  /// Creates a pass to print GC metadata.
-  ///
-  FunctionPass *createGCInfoPrinter(raw_ostream &OS);
-
   /// MachineCSE - This pass performs global CSE on machine instructions.
   extern char &MachineCSEID;
 

llvm/include/llvm/Target/CGPassBuilderOption.h

@@ -42,7 +42,6 @@ struct CGPassBuilderOption {
   bool DisableConstantHoisting = false;
   bool DisableSelectOptimize = true;
   bool PrintISelInput = false;
-  bool PrintGCInfo = false;
   bool RequiresCodeGenSCCOrder = false;
 
   RunOutliner EnableMachineOutliner = RunOutliner::TargetDefault;

llvm/lib/CodeGen/GCMetadata.cpp

@@ -24,25 +24,6 @@
 
 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)
 
@@ -84,58 +65,6 @@ void GCModuleInfo::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);

llvm/lib/CodeGen/TargetPassConfig.cpp

@@ -113,10 +113,9 @@ static cl::opt<bool> DisableMergeICmps("disable-mergeicmps",
     cl::init(false), cl::Hidden);
 static cl::opt<bool> PrintLSR("print-lsr-output", cl::Hidden,
     cl::desc("Print LLVM IR produced by the loop-reduce pass"));
-static cl::opt<bool> PrintISelInput("print-isel-input", cl::Hidden,
-    cl::desc("Print LLVM IR input to isel pass"));
-static cl::opt<bool> PrintGCInfo("print-gc", cl::Hidden,
-    cl::desc("Dump garbage collector data"));
+static cl::opt<bool>
+    PrintISelInput("print-isel-input", cl::Hidden,
+                   cl::desc("Print LLVM IR input to isel pass"));
 static cl::opt<cl::boolOrDefault>
     VerifyMachineCode("verify-machineinstrs", cl::Hidden,
                       cl::desc("Verify generated machine code"));
@@ -491,7 +490,6 @@ CGPassBuilderOption llvm::getCGPassBuilderOption() {
   SET_BOOLEAN_OPTION(DisableSelectOptimize)
   SET_BOOLEAN_OPTION(PrintLSR)
   SET_BOOLEAN_OPTION(PrintISelInput)
-  SET_BOOLEAN_OPTION(PrintGCInfo)
 
   return Opt;
 }
@@ -1211,10 +1209,7 @@ void TargetPassConfig::addMachinePasses() {
   }
 
   // GC
-  if (addGCPasses()) {
-    if (PrintGCInfo)
-      addPass(createGCInfoPrinter(dbgs()));
-  }
+  addGCPasses();
 
   // Basic block placement.
   if (getOptLevel() != CodeGenOptLevel::None)