[llvm] r226195 - Split GCStrategy.cpp into two files (NFC)
Philip Reames
listmail at philipreames.com
Thu Jan 15 11:29:42 PST 2015
Author: reames
Date: Thu Jan 15 13:29:42 2015
New Revision: 226195
URL: http://llvm.org/viewvc/llvm-project?rev=226195&view=rev
Log:
Split GCStrategy.cpp into two files (NFC)
This preparation for an update to http://reviews.llvm.org/D6811. GCStrategy.cpp will hopefully be moving into IR/, where as the lowering logic needs to stay in CodeGen/
Added:
llvm/trunk/lib/CodeGen/GCRootLowering.cpp
Modified:
llvm/trunk/lib/CodeGen/CMakeLists.txt
llvm/trunk/lib/CodeGen/GCStrategy.cpp
Modified: llvm/trunk/lib/CodeGen/CMakeLists.txt
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/CMakeLists.txt?rev=226195&r1=226194&r2=226195&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/CMakeLists.txt (original)
+++ llvm/trunk/lib/CodeGen/CMakeLists.txt Thu Jan 15 13:29:42 2015
@@ -22,6 +22,7 @@ add_llvm_library(LLVMCodeGen
ForwardControlFlowIntegrity.cpp
GCMetadata.cpp
GCMetadataPrinter.cpp
+ GCRootLowering.cpp
GCStrategy.cpp
GlobalMerge.cpp
IfConversion.cpp
Added: llvm/trunk/lib/CodeGen/GCRootLowering.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/GCRootLowering.cpp?rev=226195&view=auto
==============================================================================
--- llvm/trunk/lib/CodeGen/GCRootLowering.cpp (added)
+++ llvm/trunk/lib/CodeGen/GCRootLowering.cpp Thu Jan 15 13:29:42 2015
@@ -0,0 +1,388 @@
+//===-- GCRootLowering.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 the lowering for the gc.root mechanism.
+//
+//===----------------------------------------------------------------------===//
+
+#include "llvm/CodeGen/GCStrategy.h"
+#include "llvm/CodeGen/MachineFrameInfo.h"
+#include "llvm/CodeGen/MachineFunctionPass.h"
+#include "llvm/CodeGen/MachineInstrBuilder.h"
+#include "llvm/CodeGen/MachineModuleInfo.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
+ /// directed by the GCStrategy. It also performs automatic root initialization
+ /// and custom intrinsic lowering.
+ class LowerIntrinsics : public FunctionPass {
+ static bool NeedsDefaultLoweringPass(const GCStrategy &C);
+ static bool NeedsCustomLoweringPass(const GCStrategy &C);
+ static bool CouldBecomeSafePoint(Instruction *I);
+ bool PerformDefaultLowering(Function &F, GCStrategy &Coll);
+ static bool InsertRootInitializers(Function &F,
+ AllocaInst **Roots, unsigned Count);
+
+ public:
+ static char ID;
+
+ LowerIntrinsics();
+ const char *getPassName() const override;
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+
+ bool doInitialization(Module &M) override;
+ bool runOnFunction(Function &F) override;
+ };
+
+
+ /// 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 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,
+ MachineBasicBlock::iterator MI,
+ DebugLoc DL) const;
+
+ void FindStackOffsets(MachineFunction &MF);
+
+ public:
+ static char ID;
+
+ GCMachineCodeAnalysis();
+ void getAnalysisUsage(AnalysisUsage &AU) const override;
+
+ bool runOnMachineFunction(MachineFunction &MF) override;
+ };
+
+}
+
+// -----------------------------------------------------------------------------
+
+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) {
+ 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.
+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).
+ GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
+ assert(MI && "LowerIntrinsics didn't require GCModuleInfo!?");
+ 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,
+ 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)) {
+ StoreInst* SI = new StoreInst(ConstantPointerNull::get(cast<PointerType>(
+ cast<PointerType>((*I)->getType())->getElementType())),
+ *I);
+ SI->insertAfter(*I);
+ MadeChange = true;
+ }
+
+ return MadeChange;
+}
+
+bool LowerIntrinsics::NeedsDefaultLoweringPass(const GCStrategy &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 GCStrategy &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.hasGC())
+ return false;
+
+ GCFunctionInfo &FI = getAnalysis<GCModuleInfo>().getFunctionInfo(F);
+ GCStrategy &S = FI.getStrategy();
+
+ bool MadeChange = false;
+
+ if (NeedsDefaultLoweringPass(S))
+ MadeChange |= PerformDefaultLowering(F, 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 LowerIntrinsics::PerformDefaultLowering(Function &F, GCStrategy &S) {
+ bool LowerWr = !S.customWriteBarrier();
+ bool LowerRd = !S.customReadBarrier();
+ bool InitRoots = S.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->getArgOperand(0),
+ CI->getArgOperand(2), 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->getArgOperand(1), "", 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->getArgOperand(0)->stripPointerCasts()));
+ }
+ break;
+ default:
+ continue;
+ }
+
+ MadeChange = true;
+ }
+ }
+ }
+
+ if (Roots.size())
+ MadeChange |= InsertRootInitializers(F, Roots.begin(), Roots.size());
+
+ return MadeChange;
+}
+
+// -----------------------------------------------------------------------------
+
+char GCMachineCodeAnalysis::ID = 0;
+char &llvm::GCMachineCodeAnalysisID = GCMachineCodeAnalysis::ID;
+
+INITIALIZE_PASS(GCMachineCodeAnalysis, "gc-analysis",
+ "Analyze Machine Code For Garbage Collection", false, false)
+
+GCMachineCodeAnalysis::GCMachineCodeAnalysis()
+ : MachineFunctionPass(ID) {}
+
+void GCMachineCodeAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
+ MachineFunctionPass::getAnalysisUsage(AU);
+ AU.setPreservesAll();
+ AU.addRequired<MachineModuleInfo>();
+ AU.addRequired<GCModuleInfo>();
+}
+
+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 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)) {
+ 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 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->isCall())
+ VisitCallPoint(MI);
+}
+
+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 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->getSubtargetImpl()->getInstrInfo();
+
+ // Find the size of the stack frame.
+ FI->setFrameSize(MF.getFrameInfo()->getStackSize());
+
+ // Find all safe points.
+ if (FI->getStrategy().customSafePoints()) {
+ FI->getStrategy().findCustomSafePoints(*FI, MF);
+ } else {
+ FindSafePoints(MF);
+ }
+
+ // Find the stack offsets for all roots.
+ FindStackOffsets(MF);
+
+ return false;
+}
Modified: llvm/trunk/lib/CodeGen/GCStrategy.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/CodeGen/GCStrategy.cpp?rev=226195&r1=226194&r2=226195&view=diff
==============================================================================
--- llvm/trunk/lib/CodeGen/GCStrategy.cpp (original)
+++ llvm/trunk/lib/CodeGen/GCStrategy.cpp Thu Jan 15 13:29:42 2015
@@ -1,4 +1,4 @@
-//===-- GCStrategy.cpp - Garbage collection infrastructure -----------------===//
+//===-- GCStrategy.cpp - Garbage Collector Description --------------------===//
//
// The LLVM Compiler Infrastructure
//
@@ -7,91 +7,15 @@
//
//===----------------------------------------------------------------------===//
//
-// This file implements target- and collector-independent garbage collection
-// infrastructure.
-//
-// GCMachineCodeAnalysis identifies the GC safe points in the machine code.
-// Roots are identified in SelectionDAGISel.
+// This file implements the policy object GCStrategy which describes the
+// behavior of a given garbage collector.
//
//===----------------------------------------------------------------------===//
#include "llvm/CodeGen/GCStrategy.h"
-#include "llvm/CodeGen/MachineFrameInfo.h"
-#include "llvm/CodeGen/MachineFunctionPass.h"
-#include "llvm/CodeGen/MachineInstrBuilder.h"
-#include "llvm/CodeGen/MachineModuleInfo.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
- /// directed by the GCStrategy. It also performs automatic root initialization
- /// and custom intrinsic lowering.
- class LowerIntrinsics : public FunctionPass {
- static bool NeedsDefaultLoweringPass(const GCStrategy &C);
- static bool NeedsCustomLoweringPass(const GCStrategy &C);
- static bool CouldBecomeSafePoint(Instruction *I);
- bool PerformDefaultLowering(Function &F, GCStrategy &Coll);
- static bool InsertRootInitializers(Function &F,
- AllocaInst **Roots, unsigned Count);
-
- public:
- static char ID;
-
- LowerIntrinsics();
- const char *getPassName() const override;
- void getAnalysisUsage(AnalysisUsage &AU) const override;
-
- bool doInitialization(Module &M) override;
- bool runOnFunction(Function &F) override;
- };
-
-
- /// 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 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,
- MachineBasicBlock::iterator MI,
- DebugLoc DL) const;
-
- void FindStackOffsets(MachineFunction &MF);
-
- public:
- static char ID;
-
- GCMachineCodeAnalysis();
- void getAnalysisUsage(AnalysisUsage &AU) const override;
-
- bool runOnMachineFunction(MachineFunction &MF) override;
- };
-
-}
-
-// -----------------------------------------------------------------------------
-
GCStrategy::GCStrategy() :
UseStatepoints(false),
NeededSafePoints(0),
@@ -102,304 +26,3 @@ GCStrategy::GCStrategy() :
InitRoots(true),
UsesMetadata(false)
{}
-
-// -----------------------------------------------------------------------------
-
-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) {
- 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.
-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).
- GCModuleInfo *MI = getAnalysisIfAvailable<GCModuleInfo>();
- assert(MI && "LowerIntrinsics didn't require GCModuleInfo!?");
- 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,
- 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)) {
- StoreInst* SI = new StoreInst(ConstantPointerNull::get(cast<PointerType>(
- cast<PointerType>((*I)->getType())->getElementType())),
- *I);
- SI->insertAfter(*I);
- MadeChange = true;
- }
-
- return MadeChange;
-}
-
-bool LowerIntrinsics::NeedsDefaultLoweringPass(const GCStrategy &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 GCStrategy &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.hasGC())
- return false;
-
- GCFunctionInfo &FI = getAnalysis<GCModuleInfo>().getFunctionInfo(F);
- GCStrategy &S = FI.getStrategy();
-
- bool MadeChange = false;
-
- if (NeedsDefaultLoweringPass(S))
- MadeChange |= PerformDefaultLowering(F, 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 LowerIntrinsics::PerformDefaultLowering(Function &F, GCStrategy &S) {
- bool LowerWr = !S.customWriteBarrier();
- bool LowerRd = !S.customReadBarrier();
- bool InitRoots = S.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->getArgOperand(0),
- CI->getArgOperand(2), 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->getArgOperand(1), "", 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->getArgOperand(0)->stripPointerCasts()));
- }
- break;
- default:
- continue;
- }
-
- MadeChange = true;
- }
- }
- }
-
- if (Roots.size())
- MadeChange |= InsertRootInitializers(F, Roots.begin(), Roots.size());
-
- return MadeChange;
-}
-
-// -----------------------------------------------------------------------------
-
-char GCMachineCodeAnalysis::ID = 0;
-char &llvm::GCMachineCodeAnalysisID = GCMachineCodeAnalysis::ID;
-
-INITIALIZE_PASS(GCMachineCodeAnalysis, "gc-analysis",
- "Analyze Machine Code For Garbage Collection", false, false)
-
-GCMachineCodeAnalysis::GCMachineCodeAnalysis()
- : MachineFunctionPass(ID) {}
-
-void GCMachineCodeAnalysis::getAnalysisUsage(AnalysisUsage &AU) const {
- MachineFunctionPass::getAnalysisUsage(AU);
- AU.setPreservesAll();
- AU.addRequired<MachineModuleInfo>();
- AU.addRequired<GCModuleInfo>();
-}
-
-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 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)) {
- 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 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->isCall())
- VisitCallPoint(MI);
-}
-
-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 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->getSubtargetImpl()->getInstrInfo();
-
- // Find the size of the stack frame.
- FI->setFrameSize(MF.getFrameInfo()->getStackSize());
-
- // Find all safe points.
- 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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