// This file implements target- and collector-independent garbage collection
// infrastructure.
//
-// MachineCodeAnalysis identifies the GC safe points in the machine code. Roots
-// are identified in SelectionDAGISel.
+// GCMachineCodeAnalysis identifies the GC safe points in the machine code.
+// Roots are identified in SelectionDAGISel.
//
//===----------------------------------------------------------------------===//
#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/Target/TargetRegisterInfo.h"
+#include "llvm/CodeGen/Passes.h"
+#include "llvm/IR/Dominators.h"
+#include "llvm/IR/IntrinsicInst.h"
+#include "llvm/IR/Module.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
+#include "llvm/Target/TargetFrameLowering.h"
+#include "llvm/Target/TargetInstrInfo.h"
+#include "llvm/Target/TargetMachine.h"
+#include "llvm/Target/TargetRegisterInfo.h"
+#include "llvm/Target/TargetSubtargetInfo.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
+ /// llvm.gcwrite intrinsics, replacing them with simple loads and stores as
/// directed by the GCStrategy. It also performs automatic root initialization
/// and custom intrinsic lowering.
class LowerIntrinsics : public FunctionPass {
bool PerformDefaultLowering(Function &F, GCStrategy &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);
+ const char *getPassName() const override;
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+
+ bool doInitialization(Module &M) override;
+ bool runOnFunction(Function &F) override;
};
-
-
- /// MachineCodeAnalysis - This is a target-independent pass over the machine
+
+
+ /// GCMachineCodeAnalysis - 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
/// GCMetadata record for each function.
- class MachineCodeAnalysis : public MachineFunctionPass {
+ class GCMachineCodeAnalysis : public MachineFunctionPass {
const TargetMachine *TM;
GCFunctionInfo *FI;
MachineModuleInfo *MMI;
const TargetInstrInfo *TII;
-
+
void FindSafePoints(MachineFunction &MF);
void VisitCallPoint(MachineBasicBlock::iterator MI);
- MCSymbol *InsertLabel(MachineBasicBlock &MBB,
+ MCSymbol *InsertLabel(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
DebugLoc DL) const;
-
+
void FindStackOffsets(MachineFunction &MF);
-
+
public:
static char ID;
-
- MachineCodeAnalysis();
- const char *getPassName() const;
- void getAnalysisUsage(AnalysisUsage &AU) const;
-
- bool runOnMachineFunction(MachineFunction &MF);
+
+ GCMachineCodeAnalysis();
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+
+ bool runOnMachineFunction(MachineFunction &MF) override;
};
-
+
}
// -----------------------------------------------------------------------------
CustomReadBarriers(false),
CustomWriteBarriers(false),
CustomRoots(false),
+ CustomSafePoints(false),
InitRoots(true),
UsesMetadata(false)
{}
-GCStrategy::~GCStrategy() {
- for (iterator I = begin(), E = end(); I != E; ++I)
- delete *I;
-
- Functions.clear();
-}
-
-bool GCStrategy::initializeCustomLowering(Module &M) { return false; }
-
-bool GCStrategy::performCustomLowering(Function &F) {
- dbgs() << "gc " << getName() << " must override performCustomLowering.\n";
- llvm_unreachable(0);
- return 0;
-}
-
-GCFunctionInfo *GCStrategy::insertFunctionInfo(const Function &F) {
- GCFunctionInfo *FI = new GCFunctionInfo(F, *this);
- Functions.push_back(FI);
- return FI;
-}
-
// -----------------------------------------------------------------------------
+INITIALIZE_PASS_BEGIN(LowerIntrinsics, "gc-lowering", "GC Lowering",
+ false, false)
+INITIALIZE_PASS_DEPENDENCY(GCModuleInfo)
+INITIALIZE_PASS_END(LowerIntrinsics, "gc-lowering", "GC Lowering", false, false)
+
FunctionPass *llvm::createGCLoweringPass() {
return new LowerIntrinsics();
}
-
+
char LowerIntrinsics::ID = 0;
LowerIntrinsics::LowerIntrinsics()
- : FunctionPass(&ID) {}
+ : FunctionPass(ID) {
+ initializeLowerIntrinsicsPass(*PassRegistry::getPassRegistry());
+ }
const char *LowerIntrinsics::getPassName() const {
return "Lower Garbage Collection Instructions";
}
-
+
void LowerIntrinsics::getAnalysisUsage(AnalysisUsage &AU) const {
FunctionPass::getAnalysisUsage(AU);
AU.addRequired<GCModuleInfo>();
+ AU.addPreserved<DominatorTreeWrapperPass>();
}
/// doInitialization - If this module uses the GC intrinsics, find them now.
for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
if (!I->isDeclaration() && I->hasGC())
MI->getFunctionInfo(*I); // Instantiate the GC strategy.
-
+
bool MadeChange = false;
for (GCModuleInfo::iterator I = MI->begin(), E = MI->end(); I != E; ++I)
if (NeedsCustomLoweringPass(**I))
if ((*I)->initializeCustomLowering(M))
MadeChange = true;
-
+
return MadeChange;
}
-bool LowerIntrinsics::InsertRootInitializers(Function &F, AllocaInst **Roots,
+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 (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);
+ StoreInst* SI = new StoreInst(ConstantPointerNull::get(cast<PointerType>(
+ cast<PointerType>((*I)->getType())->getElementType())),
+ *I);
+ SI->insertAfter(*I);
MadeChange = true;
}
-
+
return MadeChange;
}
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;
}
// Quick exit for functions that do not use GC.
if (!F.hasGC())
return false;
-
+
GCFunctionInfo &FI = getAnalysis<GCModuleInfo>().getFunctionInfo(F);
GCStrategy &S = FI.getStrategy();
-
+
bool MadeChange = false;
-
+
if (NeedsDefaultLoweringPass(S))
MadeChange |= PerformDefaultLowering(F, S);
-
- if (NeedsCustomLoweringPass(S))
+
+ bool UseCustomLoweringPass = NeedsCustomLoweringPass(S);
+ if (UseCustomLoweringPass)
MadeChange |= S.performCustomLowering(F);
-
+
+ // Custom lowering may modify the CFG, so dominators must be recomputed.
+ if (UseCustomLoweringPass) {
+ if (DominatorTreeWrapperPass *DTWP =
+ getAnalysisIfAvailable<DominatorTreeWrapperPass>())
+ DTWP->getDomTree().recalculate(F);
+ }
+
return MadeChange;
}
bool LowerWr = !S.customWriteBarrier();
bool LowerRd = !S.customReadBarrier();
bool InitRoots = S.initializeRoots();
-
- SmallVector<AllocaInst*,32> Roots;
-
+
+ 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;) {
case Intrinsic::gcwrite:
if (LowerWr) {
// Replace a write barrier with a simple store.
- Value *St = new StoreInst(CI->getOperand(1), CI->getOperand(3), CI);
+ Value *St = new StoreInst(CI->getArgOperand(0),
+ CI->getArgOperand(2), CI);
CI->replaceAllUsesWith(St);
CI->eraseFromParent();
}
case Intrinsic::gcread:
if (LowerRd) {
// Replace a read barrier with a simple load.
- Value *Ld = new LoadInst(CI->getOperand(2), "", CI);
+ Value *Ld = new LoadInst(CI->getArgOperand(1), "", CI);
Ld->takeName(CI);
CI->replaceAllUsesWith(Ld);
CI->eraseFromParent();
// 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()));
+ CI->getArgOperand(0)->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 GCMachineCodeAnalysis::ID = 0;
+char &llvm::GCMachineCodeAnalysisID = GCMachineCodeAnalysis::ID;
-char MachineCodeAnalysis::ID = 0;
+INITIALIZE_PASS(GCMachineCodeAnalysis, "gc-analysis",
+ "Analyze Machine Code For Garbage Collection", false, false)
-MachineCodeAnalysis::MachineCodeAnalysis()
- : MachineFunctionPass(&ID) {}
+GCMachineCodeAnalysis::GCMachineCodeAnalysis()
+ : MachineFunctionPass(ID) {}
-const char *MachineCodeAnalysis::getPassName() const {
- return "Analyze Machine Code For Garbage Collection";
-}
-
-void MachineCodeAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
+void GCMachineCodeAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
MachineFunctionPass::getAnalysisUsage(AU);
AU.setPreservesAll();
AU.addRequired<MachineModuleInfo>();
AU.addRequired<GCModuleInfo>();
}
-MCSymbol *MachineCodeAnalysis::InsertLabel(MachineBasicBlock &MBB,
- MachineBasicBlock::iterator MI,
- DebugLoc DL) const {
+MCSymbol *GCMachineCodeAnalysis::InsertLabel(MachineBasicBlock &MBB,
+ MachineBasicBlock::iterator MI,
+ DebugLoc DL) const {
MCSymbol *Label = MBB.getParent()->getContext().CreateTempSymbol();
BuildMI(MBB, MI, DL, TII->get(TargetOpcode::GC_LABEL)).addSym(Label);
return Label;
}
-void MachineCodeAnalysis::VisitCallPoint(MachineBasicBlock::iterator CI) {
+void GCMachineCodeAnalysis::VisitCallPoint(MachineBasicBlock::iterator CI) {
// Find the return address (next instruction), too, so as to bracket the call
// instruction.
- MachineBasicBlock::iterator RAI = CI;
- ++RAI;
-
- if (FI->getStrategy().needsSafePoint(GC::PreCall))
- FI->addSafePoint(GC::PreCall, InsertLabel(*CI->getParent(), CI,
- CI->getDebugLoc()));
-
- if (FI->getStrategy().needsSafePoint(GC::PostCall))
- FI->addSafePoint(GC::PostCall, InsertLabel(*CI->getParent(), RAI,
- CI->getDebugLoc()));
+ MachineBasicBlock::iterator RAI = CI;
+ ++RAI;
+
+ if (FI->getStrategy().needsSafePoint(GC::PreCall)) {
+ MCSymbol* Label = InsertLabel(*CI->getParent(), CI, CI->getDebugLoc());
+ FI->addSafePoint(GC::PreCall, Label, CI->getDebugLoc());
+ }
+
+ if (FI->getStrategy().needsSafePoint(GC::PostCall)) {
+ MCSymbol* Label = InsertLabel(*CI->getParent(), RAI, CI->getDebugLoc());
+ FI->addSafePoint(GC::PostCall, Label, CI->getDebugLoc());
+ }
}
-void MachineCodeAnalysis::FindSafePoints(MachineFunction &MF) {
+void GCMachineCodeAnalysis::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())
+ if (MI->isCall())
VisitCallPoint(MI);
}
-void MachineCodeAnalysis::FindStackOffsets(MachineFunction &MF) {
- const TargetRegisterInfo *TRI = TM->getRegisterInfo();
- assert(TRI && "TargetRegisterInfo not available!");
-
- for (GCFunctionInfo::roots_iterator RI = FI->roots_begin(),
- RE = FI->roots_end(); RI != RE; ++RI)
- RI->StackOffset = TRI->getFrameIndexOffset(MF, RI->Num);
+void GCMachineCodeAnalysis::FindStackOffsets(MachineFunction &MF) {
+ const TargetFrameLowering *TFI = TM->getSubtargetImpl()->getFrameLowering();
+ assert(TFI && "TargetRegisterInfo not available!");
+
+ for (GCFunctionInfo::roots_iterator RI = FI->roots_begin();
+ RI != FI->roots_end();) {
+ // If the root references a dead object, no need to keep it.
+ if (MF.getFrameInfo()->isDeadObjectIndex(RI->Num)) {
+ RI = FI->removeStackRoot(RI);
+ } else {
+ RI->StackOffset = TFI->getFrameIndexOffset(MF, RI->Num);
+ ++RI;
+ }
+ }
}
-bool MachineCodeAnalysis::runOnMachineFunction(MachineFunction &MF) {
+bool GCMachineCodeAnalysis::runOnMachineFunction(MachineFunction &MF) {
// Quick exit for functions that do not use GC.
if (!MF.getFunction()->hasGC())
return false;
-
+
FI = &getAnalysis<GCModuleInfo>().getFunctionInfo(*MF.getFunction());
if (!FI->getStrategy().needsSafePoints())
return false;
-
+
TM = &MF.getTarget();
MMI = &getAnalysis<MachineModuleInfo>();
- TII = TM->getInstrInfo();
-
+ TII = TM->getSubtargetImpl()->getInstrInfo();
+
// Find the size of the stack frame.
FI->setFrameSize(MF.getFrameInfo()->getStackSize());
-
+
// Find all safe points.
- FindSafePoints(MF);
-
+ if (FI->getStrategy().customSafePoints()) {
+ FI->getStrategy().findCustomSafePoints(*FI, MF);
+ } else {
+ FindSafePoints(MF);
+ }
+
// Find the stack offsets for all roots.
FindStackOffsets(MF);
-
+
return false;
}
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