Factor GC metadata table assembly generation out of Collector in preparation for splitting AsmPrinter into its own library.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@54881 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/GCStrategy.cpp b/lib/CodeGen/GCStrategy.cpp
new file mode 100644
index 0000000..629a2e1
--- /dev/null
+++ b/lib/CodeGen/GCStrategy.cpp
@@ -0,0 +1,389 @@
+//===-- Collector.cpp - Garbage collection infrastructure -----------------===//
+//
+// The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file implements target- and collector-independent garbage collection
+// infrastructure.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/GCStrategy.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/IntrinsicInst.h"
+#include "llvm/Module.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
+#include "llvm/Target/TargetFrameInfo.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Support/Compiler.h"
+
+using namespace llvm;
+
+namespace {
+
+ /// LowerIntrinsics - This pass rewrites calls to the llvm.gcread or
+ /// llvm.gcwrite intrinsics, replacing them with simple loads and stores as
+ /// directed by the Collector. It also performs automatic root initialization
+ /// and custom intrinsic lowering.
+ class VISIBILITY_HIDDEN LowerIntrinsics : public FunctionPass {
+ static bool NeedsDefaultLoweringPass(const Collector &C);
+ static bool NeedsCustomLoweringPass(const Collector &C);
+ static bool CouldBecomeSafePoint(Instruction *I);
+ bool PerformDefaultLowering(Function &F, Collector &Coll);
+ static bool InsertRootInitializers(Function &F,
+ AllocaInst **Roots, unsigned Count);
+
+ public:
+ static char ID;
+
+ LowerIntrinsics();
+ const char *getPassName() const;
+ void getAnalysisUsage(AnalysisUsage &AU) const;
+
+ bool doInitialization(Module &M);
+ bool runOnFunction(Function &F);
+ };
+
+
+ /// MachineCodeAnalysis - This is a target-independent pass over the machine
+ /// function representation to identify safe points for the garbage collector
+ /// in the machine code. It inserts labels at safe points and populates a
+ /// CollectorMetadata record for each function.
+ class VISIBILITY_HIDDEN MachineCodeAnalysis : public MachineFunctionPass {
+ const TargetMachine *TM;
+ CollectorMetadata *MD;
+ MachineModuleInfo *MMI;
+ const TargetInstrInfo *TII;
+ MachineFrameInfo *MFI;
+
+ void FindSafePoints(MachineFunction &MF);
+ void VisitCallPoint(MachineBasicBlock::iterator MI);
+ unsigned InsertLabel(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MI) const;
+
+ void FindStackOffsets(MachineFunction &MF);
+
+ public:
+ static char ID;
+
+ MachineCodeAnalysis();
+ const char *getPassName() const;
+ void getAnalysisUsage(AnalysisUsage &AU) const;
+
+ bool runOnMachineFunction(MachineFunction &MF);
+ };
+
+}
+
+// -----------------------------------------------------------------------------
+
+Collector::Collector() :
+ NeededSafePoints(0),
+ CustomReadBarriers(false),
+ CustomWriteBarriers(false),
+ CustomRoots(false),
+ InitRoots(true),
+ UsesMetadata(false)
+{}
+
+Collector::~Collector() {
+ for (iterator I = begin(), E = end(); I != E; ++I)
+ delete *I;
+
+ Functions.clear();
+}
+
+bool Collector::initializeCustomLowering(Module &M) { return false; }
+
+bool Collector::performCustomLowering(Function &F) {
+ cerr << "gc " << getName() << " must override performCustomLowering.\n";
+ abort();
+ return 0;
+}
+
+CollectorMetadata *Collector::insertFunctionMetadata(const Function &F) {
+ CollectorMetadata *CM = new CollectorMetadata(F, *this);
+ Functions.push_back(CM);
+ return CM;
+}
+
+// -----------------------------------------------------------------------------
+
+FunctionPass *llvm::createGCLoweringPass() {
+ return new LowerIntrinsics();
+}
+
+char LowerIntrinsics::ID = 0;
+
+LowerIntrinsics::LowerIntrinsics()
+ : FunctionPass((intptr_t)&ID) {}
+
+const char *LowerIntrinsics::getPassName() const {
+ return "Lower Garbage Collection Instructions";
+}
+
+void LowerIntrinsics::getAnalysisUsage(AnalysisUsage &AU) const {
+ FunctionPass::getAnalysisUsage(AU);
+ AU.addRequired<CollectorModuleMetadata>();
+}
+
+/// doInitialization - If this module uses the GC intrinsics, find them now.
+bool LowerIntrinsics::doInitialization(Module &M) {
+ // FIXME: This is rather antisocial in the context of a JIT since it performs
+ // work against the entire module. But this cannot be done at
+ // runFunction time (initializeCustomLowering likely needs to change
+ // the module).
+ CollectorModuleMetadata *CMM = getAnalysisToUpdate<CollectorModuleMetadata>();
+ assert(CMM && "LowerIntrinsics didn't require CollectorModuleMetadata!?");
+ for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
+ if (I->hasCollector())
+ CMM->get(*I); // Instantiate the Collector.
+
+ bool MadeChange = false;
+ for (CollectorModuleMetadata::iterator I = CMM->begin(),
+ E = CMM->end(); I != E; ++I)
+ if (NeedsCustomLoweringPass(**I))
+ if ((*I)->initializeCustomLowering(M))
+ MadeChange = true;
+
+ return MadeChange;
+}
+
+bool LowerIntrinsics::InsertRootInitializers(Function &F, AllocaInst **Roots,
+ unsigned Count) {
+ // Scroll past alloca instructions.
+ BasicBlock::iterator IP = F.getEntryBlock().begin();
+ while (isa<AllocaInst>(IP)) ++IP;
+
+ // Search for initializers in the initial BB.
+ SmallPtrSet<AllocaInst*,16> InitedRoots;
+ for (; !CouldBecomeSafePoint(IP); ++IP)
+ if (StoreInst *SI = dyn_cast<StoreInst>(IP))
+ if (AllocaInst *AI =
+ dyn_cast<AllocaInst>(SI->getOperand(1)->stripPointerCasts()))
+ InitedRoots.insert(AI);
+
+ // Add root initializers.
+ bool MadeChange = false;
+
+ for (AllocaInst **I = Roots, **E = Roots + Count; I != E; ++I)
+ if (!InitedRoots.count(*I)) {
+ new StoreInst(ConstantPointerNull::get(cast<PointerType>(
+ cast<PointerType>((*I)->getType())->getElementType())),
+ *I, IP);
+ MadeChange = true;
+ }
+
+ return MadeChange;
+}
+
+bool LowerIntrinsics::NeedsDefaultLoweringPass(const Collector &C) {
+ // Default lowering is necessary only if read or write barriers have a default
+ // action. The default for roots is no action.
+ return !C.customWriteBarrier()
+ || !C.customReadBarrier()
+ || C.initializeRoots();
+}
+
+bool LowerIntrinsics::NeedsCustomLoweringPass(const Collector &C) {
+ // Custom lowering is only necessary if enabled for some action.
+ return C.customWriteBarrier()
+ || C.customReadBarrier()
+ || C.customRoots();
+}
+
+/// CouldBecomeSafePoint - Predicate to conservatively determine whether the
+/// instruction could introduce a safe point.
+bool LowerIntrinsics::CouldBecomeSafePoint(Instruction *I) {
+ // The natural definition of instructions which could introduce safe points
+ // are:
+ //
+ // - call, invoke (AfterCall, BeforeCall)
+ // - phis (Loops)
+ // - invoke, ret, unwind (Exit)
+ //
+ // However, instructions as seemingly inoccuous as arithmetic can become
+ // libcalls upon lowering (e.g., div i64 on a 32-bit platform), so instead
+ // it is necessary to take a conservative approach.
+
+ if (isa<AllocaInst>(I) || isa<GetElementPtrInst>(I) ||
+ isa<StoreInst>(I) || isa<LoadInst>(I))
+ return false;
+
+ // llvm.gcroot is safe because it doesn't do anything at runtime.
+ if (CallInst *CI = dyn_cast<CallInst>(I))
+ if (Function *F = CI->getCalledFunction())
+ if (unsigned IID = F->getIntrinsicID())
+ if (IID == Intrinsic::gcroot)
+ return false;
+
+ return true;
+}
+
+/// runOnFunction - Replace gcread/gcwrite intrinsics with loads and stores.
+/// Leave gcroot intrinsics; the code generator needs to see those.
+bool LowerIntrinsics::runOnFunction(Function &F) {
+ // Quick exit for functions that do not use GC.
+ if (!F.hasCollector()) return false;
+
+ CollectorMetadata &MD = getAnalysis<CollectorModuleMetadata>().get(F);
+ Collector &Coll = MD.getCollector();
+
+ bool MadeChange = false;
+
+ if (NeedsDefaultLoweringPass(Coll))
+ MadeChange |= PerformDefaultLowering(F, Coll);
+
+ if (NeedsCustomLoweringPass(Coll))
+ MadeChange |= Coll.performCustomLowering(F);
+
+ return MadeChange;
+}
+
+bool LowerIntrinsics::PerformDefaultLowering(Function &F, Collector &Coll) {
+ bool LowerWr = !Coll.customWriteBarrier();
+ bool LowerRd = !Coll.customReadBarrier();
+ bool InitRoots = Coll.initializeRoots();
+
+ SmallVector<AllocaInst*,32> Roots;
+
+ bool MadeChange = false;
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
+ for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E;) {
+ if (IntrinsicInst *CI = dyn_cast<IntrinsicInst>(II++)) {
+ Function *F = CI->getCalledFunction();
+ switch (F->getIntrinsicID()) {
+ case Intrinsic::gcwrite:
+ if (LowerWr) {
+ // Replace a write barrier with a simple store.
+ Value *St = new StoreInst(CI->getOperand(1), CI->getOperand(3), CI);
+ CI->replaceAllUsesWith(St);
+ CI->eraseFromParent();
+ }
+ break;
+ case Intrinsic::gcread:
+ if (LowerRd) {
+ // Replace a read barrier with a simple load.
+ Value *Ld = new LoadInst(CI->getOperand(2), "", CI);
+ Ld->takeName(CI);
+ CI->replaceAllUsesWith(Ld);
+ CI->eraseFromParent();
+ }
+ break;
+ case Intrinsic::gcroot:
+ if (InitRoots) {
+ // Initialize the GC root, but do not delete the intrinsic. The
+ // backend needs the intrinsic to flag the stack slot.
+ Roots.push_back(cast<AllocaInst>(
+ CI->getOperand(1)->stripPointerCasts()));
+ }
+ break;
+ default:
+ continue;
+ }
+
+ MadeChange = true;
+ }
+ }
+ }
+
+ if (Roots.size())
+ MadeChange |= InsertRootInitializers(F, Roots.begin(), Roots.size());
+
+ return MadeChange;
+}
+
+// -----------------------------------------------------------------------------
+
+FunctionPass *llvm::createGCMachineCodeAnalysisPass() {
+ return new MachineCodeAnalysis();
+}
+
+char MachineCodeAnalysis::ID = 0;
+
+MachineCodeAnalysis::MachineCodeAnalysis()
+ : MachineFunctionPass(intptr_t(&ID)) {}
+
+const char *MachineCodeAnalysis::getPassName() const {
+ return "Analyze Machine Code For Garbage Collection";
+}
+
+void MachineCodeAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
+ MachineFunctionPass::getAnalysisUsage(AU);
+ AU.setPreservesAll();
+ AU.addRequired<MachineModuleInfo>();
+ AU.addRequired<CollectorModuleMetadata>();
+}
+
+unsigned MachineCodeAnalysis::InsertLabel(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MI) const {
+ unsigned Label = MMI->NextLabelID();
+ BuildMI(MBB, MI, TII->get(TargetInstrInfo::GC_LABEL)).addImm(Label);
+ return Label;
+}
+
+void MachineCodeAnalysis::VisitCallPoint(MachineBasicBlock::iterator CI) {
+ // Find the return address (next instruction), too, so as to bracket the call
+ // instruction.
+ MachineBasicBlock::iterator RAI = CI;
+ ++RAI;
+
+ if (MD->getCollector().needsSafePoint(GC::PreCall))
+ MD->addSafePoint(GC::PreCall, InsertLabel(*CI->getParent(), CI));
+
+ if (MD->getCollector().needsSafePoint(GC::PostCall))
+ MD->addSafePoint(GC::PostCall, InsertLabel(*CI->getParent(), RAI));
+}
+
+void MachineCodeAnalysis::FindSafePoints(MachineFunction &MF) {
+ for (MachineFunction::iterator BBI = MF.begin(),
+ BBE = MF.end(); BBI != BBE; ++BBI)
+ for (MachineBasicBlock::iterator MI = BBI->begin(),
+ ME = BBI->end(); MI != ME; ++MI)
+ if (MI->getDesc().isCall())
+ VisitCallPoint(MI);
+}
+
+void MachineCodeAnalysis::FindStackOffsets(MachineFunction &MF) {
+ uint64_t StackSize = MFI->getStackSize();
+ uint64_t OffsetAdjustment = MFI->getOffsetAdjustment();
+ uint64_t OffsetOfLocalArea = TM->getFrameInfo()->getOffsetOfLocalArea();
+
+ for (CollectorMetadata::roots_iterator RI = MD->roots_begin(),
+ RE = MD->roots_end(); RI != RE; ++RI)
+ RI->StackOffset = MFI->getObjectOffset(RI->Num) + StackSize
+ - OffsetOfLocalArea + OffsetAdjustment;
+}
+
+bool MachineCodeAnalysis::runOnMachineFunction(MachineFunction &MF) {
+ // Quick exit for functions that do not use GC.
+ if (!MF.getFunction()->hasCollector()) return false;
+
+ MD = &getAnalysis<CollectorModuleMetadata>().get(*MF.getFunction());
+ if (!MD->getCollector().needsSafePoints())
+ return false;
+
+ TM = &MF.getTarget();
+ MMI = &getAnalysis<MachineModuleInfo>();
+ TII = TM->getInstrInfo();
+ MFI = MF.getFrameInfo();
+
+ // Find the size of the stack frame.
+ MD->setFrameSize(MFI->getStackSize());
+
+ // Find all safe points.
+ FindSafePoints(MF);
+
+ // Find the stack offsets for all roots.
+ FindStackOffsets(MF);
+
+ return false;
+}