-//===- SjLjEHPass.cpp - Eliminate Invoke & Unwind instructions -----------===//
+//===- SjLjEHPrepare.cpp - Eliminate Invoke & Unwind instructions ---------===//
//
// The LLVM Compiler Infrastructure
//
//===----------------------------------------------------------------------===//
#define DEBUG_TYPE "sjljehprepare"
-#include "llvm/Transforms/Scalar.h"
-#include "llvm/Constants.h"
-#include "llvm/DerivedTypes.h"
-#include "llvm/Instructions.h"
-#include "llvm/Intrinsics.h"
-#include "llvm/LLVMContext.h"
-#include "llvm/Module.h"
-#include "llvm/Pass.h"
#include "llvm/CodeGen/Passes.h"
-#include "llvm/Transforms/Utils/BasicBlockUtils.h"
-#include "llvm/Transforms/Utils/Local.h"
#include "llvm/ADT/DenseMap.h"
-#include "llvm/ADT/Statistic.h"
+#include "llvm/ADT/SetVector.h"
+#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/Statistic.h"
+#include "llvm/IR/Constants.h"
+#include "llvm/IR/DataLayout.h"
+#include "llvm/IR/DerivedTypes.h"
+#include "llvm/IR/IRBuilder.h"
+#include "llvm/IR/Instructions.h"
+#include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/LLVMContext.h"
+#include "llvm/IR/Module.h"
+#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
-#include "llvm/Support/Compiler.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetLowering.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/Transforms/Utils/BasicBlockUtils.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include <set>
using namespace llvm;
STATISTIC(NumInvokes, "Number of invokes replaced");
-STATISTIC(NumUnwinds, "Number of unwinds replaced");
STATISTIC(NumSpilled, "Number of registers live across unwind edges");
namespace {
- class VISIBILITY_HIDDEN SjLjEHPass : public FunctionPass {
-
+ class SjLjEHPrepare : public FunctionPass {
const TargetLowering *TLI;
-
- const Type *FunctionContextTy;
+ Type *FunctionContextTy;
Constant *RegisterFn;
Constant *UnregisterFn;
- Constant *ResumeFn;
Constant *BuiltinSetjmpFn;
Constant *FrameAddrFn;
+ Constant *StackAddrFn;
+ Constant *StackRestoreFn;
Constant *LSDAAddrFn;
Value *PersonalityFn;
- Constant *Selector32Fn;
- Constant *Selector64Fn;
- Constant *ExceptionFn;
-
- Value *CallSite;
+ Constant *CallSiteFn;
+ Constant *FuncCtxFn;
+ AllocaInst *FuncCtx;
public:
static char ID; // Pass identification, replacement for typeid
- explicit SjLjEHPass(const TargetLowering *tli = NULL)
- : FunctionPass(&ID), TLI(tli) { }
+ explicit SjLjEHPrepare(const TargetLowering *tli = NULL)
+ : FunctionPass(ID), TLI(tli) { }
bool doInitialization(Module &M);
bool runOnFunction(Function &F);
- virtual void getAnalysisUsage(AnalysisUsage &AU) const { }
+ virtual void getAnalysisUsage(AnalysisUsage &AU) const {}
const char *getPassName() const {
return "SJLJ Exception Handling preparation";
}
private:
- void markInvokeCallSite(InvokeInst *II, unsigned InvokeNo,
- Value *CallSite);
- void splitLiveRangesLiveAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes);
- bool insertSjLjEHSupport(Function &F);
+ bool setupEntryBlockAndCallSites(Function &F);
+ void substituteLPadValues(LandingPadInst *LPI, Value *ExnVal,
+ Value *SelVal);
+ Value *setupFunctionContext(Function &F, ArrayRef<LandingPadInst*> LPads);
+ void lowerIncomingArguments(Function &F);
+ void lowerAcrossUnwindEdges(Function &F, ArrayRef<InvokeInst*> Invokes);
+ void insertCallSiteStore(Instruction *I, int Number);
};
} // end anonymous namespace
-char SjLjEHPass::ID = 0;
+char SjLjEHPrepare::ID = 0;
-// Public Interface To the SjLjEHPass pass.
-FunctionPass *llvm::createSjLjEHPass(const TargetLowering *TLI) {
- return new SjLjEHPass(TLI);
+// Public Interface To the SjLjEHPrepare pass.
+FunctionPass *llvm::createSjLjEHPreparePass(const TargetLowering *TLI) {
+ return new SjLjEHPrepare(TLI);
}
// doInitialization - Set up decalarations and types needed to process
// exceptions.
-bool SjLjEHPass::doInitialization(Module &M) {
+bool SjLjEHPrepare::doInitialization(Module &M) {
// Build the function context structure.
// builtin_setjmp uses a five word jbuf
- const Type *VoidPtrTy =
- PointerType::getUnqual(Type::getInt8Ty(M.getContext()));
- const Type *Int32Ty = Type::getInt32Ty(M.getContext());
+ Type *VoidPtrTy = Type::getInt8PtrTy(M.getContext());
+ Type *Int32Ty = Type::getInt32Ty(M.getContext());
FunctionContextTy =
- StructType::get(M.getContext(),
- VoidPtrTy, // __prev
+ StructType::get(VoidPtrTy, // __prev
Int32Ty, // call_site
ArrayType::get(Int32Ty, 4), // __data
VoidPtrTy, // __personality
Type::getVoidTy(M.getContext()),
PointerType::getUnqual(FunctionContextTy),
(Type *)0);
- ResumeFn =
- M.getOrInsertFunction("_Unwind_SjLj_Resume",
- Type::getVoidTy(M.getContext()),
- VoidPtrTy,
- (Type *)0);
FrameAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::frameaddress);
+ StackAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::stacksave);
+ StackRestoreFn = Intrinsic::getDeclaration(&M, Intrinsic::stackrestore);
BuiltinSetjmpFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_setjmp);
LSDAAddrFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_lsda);
- Selector32Fn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector_i32);
- Selector64Fn = Intrinsic::getDeclaration(&M, Intrinsic::eh_selector_i64);
- ExceptionFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_exception);
+ CallSiteFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_callsite);
+ FuncCtxFn = Intrinsic::getDeclaration(&M, Intrinsic::eh_sjlj_functioncontext);
PersonalityFn = 0;
return true;
}
-/// markInvokeCallSite - Insert code to mark the call_site for this invoke
-void SjLjEHPass::markInvokeCallSite(InvokeInst *II, unsigned InvokeNo,
- Value *CallSite) {
- ConstantInt *CallSiteNoC= ConstantInt::get(Type::getInt32Ty(II->getContext()),
- InvokeNo);
-
- // If the unwind edge has phi nodes, split the edge.
- if (isa<PHINode>(II->getUnwindDest()->begin())) {
- SplitCriticalEdge(II, 1, this);
-
- // If there are any phi nodes left, they must have a single predecessor.
- while (PHINode *PN = dyn_cast<PHINode>(II->getUnwindDest()->begin())) {
- PN->replaceAllUsesWith(PN->getIncomingValue(0));
- PN->eraseFromParent();
- }
- }
-
- // Insert a store of the invoke num before the invoke and store zero into the
- // location afterward.
- new StoreInst(CallSiteNoC, CallSite, true, II); // volatile
-
- // We still want this to look like an invoke so we emit the LSDA properly
- // FIXME: ??? Or will this cause strangeness with mis-matched IDs like
- // when it was in the front end?
+/// insertCallSiteStore - Insert a store of the call-site value to the
+/// function context
+void SjLjEHPrepare::insertCallSiteStore(Instruction *I, int Number) {
+ IRBuilder<> Builder(I);
+
+ // Get a reference to the call_site field.
+ Type *Int32Ty = Type::getInt32Ty(I->getContext());
+ Value *Zero = ConstantInt::get(Int32Ty, 0);
+ Value *One = ConstantInt::get(Int32Ty, 1);
+ Value *Idxs[2] = { Zero, One };
+ Value *CallSite = Builder.CreateGEP(FuncCtx, Idxs, "call_site");
+
+ // Insert a store of the call-site number
+ ConstantInt *CallSiteNoC = ConstantInt::get(Type::getInt32Ty(I->getContext()),
+ Number);
+ Builder.CreateStore(CallSiteNoC, CallSite, true/*volatile*/);
}
/// MarkBlocksLiveIn - Insert BB and all of its predescessors into LiveBBs until
/// we reach blocks we've already seen.
-static void MarkBlocksLiveIn(BasicBlock *BB, std::set<BasicBlock*> &LiveBBs) {
- if (!LiveBBs.insert(BB).second) return; // already been here.
+static void MarkBlocksLiveIn(BasicBlock *BB,
+ SmallPtrSet<BasicBlock*, 64> &LiveBBs) {
+ if (!LiveBBs.insert(BB)) return; // already been here.
for (pred_iterator PI = pred_begin(BB), E = pred_end(BB); PI != E; ++PI)
MarkBlocksLiveIn(*PI, LiveBBs);
}
-/// splitLiveRangesAcrossInvokes - Each value that is live across an unwind edge
-/// we spill into a stack location, guaranteeing that there is nothing live
-/// across the unwind edge. This process also splits all critical edges
-/// coming out of invoke's.
-void SjLjEHPass::
-splitLiveRangesLiveAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) {
- // First step, split all critical edges from invoke instructions.
- for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
- InvokeInst *II = Invokes[i];
- SplitCriticalEdge(II, 0, this);
- SplitCriticalEdge(II, 1, this);
- assert(!isa<PHINode>(II->getNormalDest()) &&
- !isa<PHINode>(II->getUnwindDest()) &&
- "critical edge splitting left single entry phi nodes?");
+/// substituteLPadValues - Substitute the values returned by the landingpad
+/// instruction with those returned by the personality function.
+void SjLjEHPrepare::substituteLPadValues(LandingPadInst *LPI, Value *ExnVal,
+ Value *SelVal) {
+ SmallVector<Value*, 8> UseWorkList(LPI->use_begin(), LPI->use_end());
+ while (!UseWorkList.empty()) {
+ Value *Val = UseWorkList.pop_back_val();
+ ExtractValueInst *EVI = dyn_cast<ExtractValueInst>(Val);
+ if (!EVI) continue;
+ if (EVI->getNumIndices() != 1) continue;
+ if (*EVI->idx_begin() == 0)
+ EVI->replaceAllUsesWith(ExnVal);
+ else if (*EVI->idx_begin() == 1)
+ EVI->replaceAllUsesWith(SelVal);
+ if (EVI->getNumUses() == 0)
+ EVI->eraseFromParent();
+ }
+
+ if (LPI->getNumUses() == 0) return;
+
+ // There are still some uses of LPI. Construct an aggregate with the exception
+ // values and replace the LPI with that aggregate.
+ Type *LPadType = LPI->getType();
+ Value *LPadVal = UndefValue::get(LPadType);
+ IRBuilder<>
+ Builder(llvm::next(BasicBlock::iterator(cast<Instruction>(SelVal))));
+ LPadVal = Builder.CreateInsertValue(LPadVal, ExnVal, 0, "lpad.val");
+ LPadVal = Builder.CreateInsertValue(LPadVal, SelVal, 1, "lpad.val");
+
+ LPI->replaceAllUsesWith(LPadVal);
+}
+
+/// setupFunctionContext - Allocate the function context on the stack and fill
+/// it with all of the data that we know at this point.
+Value *SjLjEHPrepare::
+setupFunctionContext(Function &F, ArrayRef<LandingPadInst*> LPads) {
+ BasicBlock *EntryBB = F.begin();
+
+ // Create an alloca for the incoming jump buffer ptr and the new jump buffer
+ // that needs to be restored on all exits from the function. This is an alloca
+ // because the value needs to be added to the global context list.
+ unsigned Align =
+ TLI->getDataLayout()->getPrefTypeAlignment(FunctionContextTy);
+ FuncCtx =
+ new AllocaInst(FunctionContextTy, 0, Align, "fn_context", EntryBB->begin());
+
+ // Fill in the function context structure.
+ for (unsigned I = 0, E = LPads.size(); I != E; ++I) {
+ LandingPadInst *LPI = LPads[I];
+ IRBuilder<> Builder(LPI->getParent()->getFirstInsertionPt());
+
+ // Reference the __data field.
+ Value *FCData = Builder.CreateConstGEP2_32(FuncCtx, 0, 2, "__data");
+
+ // The exception values come back in context->__data[0].
+ Value *ExceptionAddr = Builder.CreateConstGEP2_32(FCData, 0, 0,
+ "exception_gep");
+ Value *ExnVal = Builder.CreateLoad(ExceptionAddr, true, "exn_val");
+ ExnVal = Builder.CreateIntToPtr(ExnVal, Builder.getInt8PtrTy());
+
+ Value *SelectorAddr = Builder.CreateConstGEP2_32(FCData, 0, 1,
+ "exn_selector_gep");
+ Value *SelVal = Builder.CreateLoad(SelectorAddr, true, "exn_selector_val");
+
+ substituteLPadValues(LPI, ExnVal, SelVal);
}
- Function *F = Invokes.back()->getParent()->getParent();
-
- // To avoid having to handle incoming arguments specially, we lower each arg
- // to a copy instruction in the entry block. This ensures that the argument
- // value itself cannot be live across the entry block.
- BasicBlock::iterator AfterAllocaInsertPt = F->begin()->begin();
- while (isa<AllocaInst>(AfterAllocaInsertPt) &&
- isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsertPt)->getArraySize()))
- ++AfterAllocaInsertPt;
- for (Function::arg_iterator AI = F->arg_begin(), E = F->arg_end();
- AI != E; ++AI) {
- // This is always a no-op cast because we're casting AI to AI->getType() so
- // src and destination types are identical. BitCast is the only possibility.
- CastInst *NC = new BitCastInst(
- AI, AI->getType(), AI->getName()+".tmp", AfterAllocaInsertPt);
- AI->replaceAllUsesWith(NC);
- // Normally its is forbidden to replace a CastInst's operand because it
- // could cause the opcode to reflect an illegal conversion. However, we're
- // replacing it here with the same value it was constructed with to simply
- // make NC its user.
- NC->setOperand(0, AI);
+ // Personality function
+ IRBuilder<> Builder(EntryBB->getTerminator());
+ if (!PersonalityFn)
+ PersonalityFn = LPads[0]->getPersonalityFn();
+ Value *PersonalityFieldPtr = Builder.CreateConstGEP2_32(FuncCtx, 0, 3,
+ "pers_fn_gep");
+ Builder.CreateStore(PersonalityFn, PersonalityFieldPtr, /*isVolatile=*/true);
+
+ // LSDA address
+ Value *LSDA = Builder.CreateCall(LSDAAddrFn, "lsda_addr");
+ Value *LSDAFieldPtr = Builder.CreateConstGEP2_32(FuncCtx, 0, 4, "lsda_gep");
+ Builder.CreateStore(LSDA, LSDAFieldPtr, /*isVolatile=*/true);
+
+ return FuncCtx;
+}
+
+/// lowerIncomingArguments - To avoid having to handle incoming arguments
+/// specially, we lower each arg to a copy instruction in the entry block. This
+/// ensures that the argument value itself cannot be live out of the entry
+/// block.
+void SjLjEHPrepare::lowerIncomingArguments(Function &F) {
+ BasicBlock::iterator AfterAllocaInsPt = F.begin()->begin();
+ while (isa<AllocaInst>(AfterAllocaInsPt) &&
+ isa<ConstantInt>(cast<AllocaInst>(AfterAllocaInsPt)->getArraySize()))
+ ++AfterAllocaInsPt;
+
+ for (Function::arg_iterator
+ AI = F.arg_begin(), AE = F.arg_end(); AI != AE; ++AI) {
+ Type *Ty = AI->getType();
+
+ // Aggregate types can't be cast, but are legal argument types, so we have
+ // to handle them differently. We use an extract/insert pair as a
+ // lightweight method to achieve the same goal.
+ if (isa<StructType>(Ty) || isa<ArrayType>(Ty) || isa<VectorType>(Ty)) {
+ Instruction *EI = ExtractValueInst::Create(AI, 0, "", AfterAllocaInsPt);
+ Instruction *NI = InsertValueInst::Create(AI, EI, 0);
+ NI->insertAfter(EI);
+ AI->replaceAllUsesWith(NI);
+
+ // Set the operand of the instructions back to the AllocaInst.
+ EI->setOperand(0, AI);
+ NI->setOperand(0, AI);
+ } else {
+ // This is always a no-op cast because we're casting AI to AI->getType()
+ // so src and destination types are identical. BitCast is the only
+ // possibility.
+ CastInst *NC =
+ new BitCastInst(AI, AI->getType(), AI->getName() + ".tmp",
+ AfterAllocaInsPt);
+ AI->replaceAllUsesWith(NC);
+
+ // Set the operand of the cast instruction back to the AllocaInst.
+ // Normally it's forbidden to replace a CastInst's operand because it
+ // could cause the opcode to reflect an illegal conversion. However, we're
+ // replacing it here with the same value it was constructed with. We do
+ // this because the above replaceAllUsesWith() clobbered the operand, but
+ // we want this one to remain.
+ NC->setOperand(0, AI);
+ }
}
+}
+/// lowerAcrossUnwindEdges - Find all variables which are alive across an unwind
+/// edge and spill them.
+void SjLjEHPrepare::lowerAcrossUnwindEdges(Function &F,
+ ArrayRef<InvokeInst*> Invokes) {
// Finally, scan the code looking for instructions with bad live ranges.
- for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB)
- for (BasicBlock::iterator II = BB->begin(), E = BB->end(); II != E; ++II) {
- // Ignore obvious cases we don't have to handle. In particular, most
+ for (Function::iterator
+ BB = F.begin(), BBE = F.end(); BB != BBE; ++BB) {
+ for (BasicBlock::iterator
+ II = BB->begin(), IIE = BB->end(); II != IIE; ++II) {
+ // Ignore obvious cases we don't have to handle. In particular, most
// instructions either have no uses or only have a single use inside the
- // current block. Ignore them quickly.
+ // current block. Ignore them quickly.
Instruction *Inst = II;
if (Inst->use_empty()) continue;
if (Inst->hasOneUse() &&
// If this is an alloca in the entry block, it's not a real register
// value.
if (AllocaInst *AI = dyn_cast<AllocaInst>(Inst))
- if (isa<ConstantInt>(AI->getArraySize()) && BB == F->begin())
+ if (isa<ConstantInt>(AI->getArraySize()) && BB == F.begin())
continue;
// Avoid iterator invalidation by copying users to a temporary vector.
- SmallVector<Instruction*,16> Users;
- for (Value::use_iterator UI = Inst->use_begin(), E = Inst->use_end();
- UI != E; ++UI) {
+ SmallVector<Instruction*, 16> Users;
+ for (Value::use_iterator
+ UI = Inst->use_begin(), E = Inst->use_end(); UI != E; ++UI) {
Instruction *User = cast<Instruction>(*UI);
if (User->getParent() != BB || isa<PHINode>(User))
Users.push_back(User);
}
// Find all of the blocks that this value is live in.
- std::set<BasicBlock*> LiveBBs;
+ SmallPtrSet<BasicBlock*, 64> LiveBBs;
LiveBBs.insert(Inst->getParent());
while (!Users.empty()) {
Instruction *U = Users.back();
for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest();
if (UnwindBlock != BB && LiveBBs.count(UnwindBlock)) {
+ DEBUG(dbgs() << "SJLJ Spill: " << *Inst << " around "
+ << UnwindBlock->getName() << "\n");
NeedsSpill = true;
+ break;
}
}
// If we decided we need a spill, do it.
+ // FIXME: Spilling this way is overkill, as it forces all uses of
+ // the value to be reloaded from the stack slot, even those that aren't
+ // in the unwind blocks. We should be more selective.
if (NeedsSpill) {
- ++NumSpilled;
DemoteRegToStack(*Inst, true);
+ ++NumSpilled;
}
}
+ }
+
+ // Go through the landing pads and remove any PHIs there.
+ for (unsigned i = 0, e = Invokes.size(); i != e; ++i) {
+ BasicBlock *UnwindBlock = Invokes[i]->getUnwindDest();
+ LandingPadInst *LPI = UnwindBlock->getLandingPadInst();
+
+ // Place PHIs into a set to avoid invalidating the iterator.
+ SmallPtrSet<PHINode*, 8> PHIsToDemote;
+ for (BasicBlock::iterator
+ PN = UnwindBlock->begin(); isa<PHINode>(PN); ++PN)
+ PHIsToDemote.insert(cast<PHINode>(PN));
+ if (PHIsToDemote.empty()) continue;
+
+ // Demote the PHIs to the stack.
+ for (SmallPtrSet<PHINode*, 8>::iterator
+ I = PHIsToDemote.begin(), E = PHIsToDemote.end(); I != E; ++I)
+ DemotePHIToStack(*I);
+
+ // Move the landingpad instruction back to the top of the landing pad block.
+ LPI->moveBefore(UnwindBlock->begin());
+ }
}
-bool SjLjEHPass::insertSjLjEHSupport(Function &F) {
- SmallVector<ReturnInst*,16> Returns;
- SmallVector<UnwindInst*,16> Unwinds;
- SmallVector<InvokeInst*,16> Invokes;
+/// setupEntryBlockAndCallSites - Setup the entry block by creating and filling
+/// the function context and marking the call sites with the appropriate
+/// values. These values are used by the DWARF EH emitter.
+bool SjLjEHPrepare::setupEntryBlockAndCallSites(Function &F) {
+ SmallVector<ReturnInst*, 16> Returns;
+ SmallVector<InvokeInst*, 16> Invokes;
+ SmallSetVector<LandingPadInst*, 16> LPads;
- // Look through the terminators of the basic blocks to find invokes, returns
- // and unwinds
+ // Look through the terminators of the basic blocks to find invokes.
for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
- if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
- // Remember all return instructions in case we insert an invoke into this
- // function.
- Returns.push_back(RI);
- } else if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
+ if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator())) {
Invokes.push_back(II);
- } else if (UnwindInst *UI = dyn_cast<UnwindInst>(BB->getTerminator())) {
- Unwinds.push_back(UI);
- }
- // If we don't have any invokes or unwinds, there's nothing to do.
- if (Unwinds.empty() && Invokes.empty()) return false;
-
- // Find the eh.selector.* and eh.exception calls. We'll use the first
- // eh.selector to determine the right personality function to use. For
- // SJLJ, we always use the same personality for the whole function,
- // not on a per-selector basis.
- // FIXME: That's a bit ugly. Better way?
- SmallVector<CallInst*,16> EH_Selectors;
- SmallVector<CallInst*,16> EH_Exceptions;
- for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
- for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
- if (CallInst *CI = dyn_cast<CallInst>(I)) {
- if (CI->getCalledFunction() == Selector32Fn ||
- CI->getCalledFunction() == Selector64Fn) {
- if (!PersonalityFn) PersonalityFn = CI->getOperand(2);
- EH_Selectors.push_back(CI);
- } else if (CI->getCalledFunction() == ExceptionFn) {
- EH_Exceptions.push_back(CI);
- }
- }
+ LPads.insert(II->getUnwindDest()->getLandingPadInst());
+ } else if (ReturnInst *RI = dyn_cast<ReturnInst>(BB->getTerminator())) {
+ Returns.push_back(RI);
}
- }
- // If we don't have any eh.selector calls, we can't determine the personality
- // function. Without a personality function, we can't process exceptions.
- if (!PersonalityFn) return false;
+
+ if (Invokes.empty()) return false;
NumInvokes += Invokes.size();
- NumUnwinds += Unwinds.size();
-
- if (!Invokes.empty()) {
- // We have invokes, so we need to add register/unregister calls to get
- // this function onto the global unwind stack.
-
- BasicBlock *EntryBB = F.begin();
- // Create an alloca for the incoming jump buffer ptr and the new jump buffer
- // that needs to be restored on all exits from the function. This is an
- // alloca because the value needs to be added to the global context list.
- unsigned Align = 4; // FIXME: Should be a TLI check?
- AllocaInst *FunctionContext =
- new AllocaInst(FunctionContextTy, 0, Align,
- "fcn_context", F.begin()->begin());
-
- Value *Idxs[2];
- const Type *Int32Ty = Type::getInt32Ty(F.getContext());
- Value *Zero = ConstantInt::get(Int32Ty, 0);
- // We need to also keep around a reference to the call_site field
- Idxs[0] = Zero;
- Idxs[1] = ConstantInt::get(Int32Ty, 1);
- CallSite = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2,
- "call_site",
- EntryBB->getTerminator());
-
- // The exception selector comes back in context->data[1]
- Idxs[1] = ConstantInt::get(Int32Ty, 2);
- Value *FCData = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2,
- "fc_data",
- EntryBB->getTerminator());
- Idxs[1] = ConstantInt::get(Int32Ty, 1);
- Value *SelectorAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2,
- "exc_selector_gep",
- EntryBB->getTerminator());
- // The exception value comes back in context->data[0]
- Idxs[1] = Zero;
- Value *ExceptionAddr = GetElementPtrInst::Create(FCData, Idxs, Idxs+2,
- "exception_gep",
- EntryBB->getTerminator());
-
- // The result of the eh.selector call will be replaced with a
- // a reference to the selector value returned in the function
- // context. We leave the selector itself so the EH analysis later
- // can use it.
- for (int i = 0, e = EH_Selectors.size(); i < e; ++i) {
- CallInst *I = EH_Selectors[i];
- Value *SelectorVal = new LoadInst(SelectorAddr, "select_val", true, I);
- I->replaceAllUsesWith(SelectorVal);
- }
- // eh.exception calls are replaced with references to the proper
- // location in the context. Unlike eh.selector, the eh.exception
- // calls are removed entirely.
- for (int i = 0, e = EH_Exceptions.size(); i < e; ++i) {
- CallInst *I = EH_Exceptions[i];
- // Possible for there to be duplicates, so check to make sure
- // the instruction hasn't already been removed.
- if (!I->getParent()) continue;
- Value *Val = new LoadInst(ExceptionAddr, "exception", true, I);
- Type *Ty = PointerType::getUnqual(Type::getInt8Ty(F.getContext()));
- Val = CastInst::Create(Instruction::IntToPtr, Val, Ty, "", I);
-
- I->replaceAllUsesWith(Val);
- I->eraseFromParent();
- }
+ lowerIncomingArguments(F);
+ lowerAcrossUnwindEdges(F, Invokes);
+ Value *FuncCtx =
+ setupFunctionContext(F, makeArrayRef(LPads.begin(), LPads.end()));
+ BasicBlock *EntryBB = F.begin();
+ IRBuilder<> Builder(EntryBB->getTerminator());
+ // Get a reference to the jump buffer.
+ Value *JBufPtr = Builder.CreateConstGEP2_32(FuncCtx, 0, 5, "jbuf_gep");
- // The entry block changes to have the eh.sjlj.setjmp, with a conditional
- // branch to a dispatch block for non-zero returns. If we return normally,
- // we're not handling an exception and just register the function context
- // and continue.
-
- // Create the dispatch block. The dispatch block is basically a big switch
- // statement that goes to all of the invoke landing pads.
- BasicBlock *DispatchBlock =
- BasicBlock::Create(F.getContext(), "eh.sjlj.setjmp.catch", &F);
-
- // Insert a load in the Catch block, and a switch on its value. By default,
- // we go to a block that just does an unwind (which is the correct action
- // for a standard call).
- BasicBlock *UnwindBlock = BasicBlock::Create(F.getContext(), "unwindbb", &F);
- Unwinds.push_back(new UnwindInst(F.getContext(), UnwindBlock));
-
- Value *DispatchLoad = new LoadInst(CallSite, "invoke.num", true,
- DispatchBlock);
- SwitchInst *DispatchSwitch =
- SwitchInst::Create(DispatchLoad, UnwindBlock, Invokes.size(), DispatchBlock);
- // Split the entry block to insert the conditional branch for the setjmp.
- BasicBlock *ContBlock = EntryBB->splitBasicBlock(EntryBB->getTerminator(),
- "eh.sjlj.setjmp.cont");
-
- // Populate the Function Context
- // 1. LSDA address
- // 2. Personality function address
- // 3. jmpbuf (save FP and call eh.sjlj.setjmp)
-
- // LSDA address
- Idxs[0] = Zero;
- Idxs[1] = ConstantInt::get(Int32Ty, 4);
- Value *LSDAFieldPtr =
- GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2,
- "lsda_gep",
- EntryBB->getTerminator());
- Value *LSDA = CallInst::Create(LSDAAddrFn, "lsda_addr",
- EntryBB->getTerminator());
- new StoreInst(LSDA, LSDAFieldPtr, true, EntryBB->getTerminator());
-
- Idxs[1] = ConstantInt::get(Int32Ty, 3);
- Value *PersonalityFieldPtr =
- GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2,
- "lsda_gep",
- EntryBB->getTerminator());
- new StoreInst(PersonalityFn, PersonalityFieldPtr, true,
- EntryBB->getTerminator());
-
- // Save the frame pointer.
- Idxs[1] = ConstantInt::get(Int32Ty, 5);
- Value *FieldPtr
- = GetElementPtrInst::Create(FunctionContext, Idxs, Idxs+2,
- "jbuf_gep",
- EntryBB->getTerminator());
- Idxs[1] = ConstantInt::get(Int32Ty, 0);
- Value *ElemPtr =
- GetElementPtrInst::Create(FieldPtr, Idxs, Idxs+2, "jbuf_fp_gep",
- EntryBB->getTerminator());
-
- Value *Val = CallInst::Create(FrameAddrFn,
- ConstantInt::get(Int32Ty, 0),
- "fp",
- EntryBB->getTerminator());
- new StoreInst(Val, ElemPtr, true, EntryBB->getTerminator());
- // Call the setjmp instrinsic. It fills in the rest of the jmpbuf
- Value *SetjmpArg =
- CastInst::Create(Instruction::BitCast, FieldPtr,
- Type::getInt8Ty(F.getContext())->getPointerTo(), "",
- EntryBB->getTerminator());
- Value *DispatchVal = CallInst::Create(BuiltinSetjmpFn, SetjmpArg,
- "dispatch",
- EntryBB->getTerminator());
- // check the return value of the setjmp. non-zero goes to dispatcher
- Value *IsNormal = new ICmpInst(EntryBB->getTerminator(),
- ICmpInst::ICMP_EQ, DispatchVal, Zero,
- "notunwind");
- // Nuke the uncond branch.
- EntryBB->getTerminator()->eraseFromParent();
-
- // Put in a new condbranch in its place.
- BranchInst::Create(ContBlock, DispatchBlock, IsNormal, EntryBB);
-
- // Register the function context and make sure it's known to not throw
- CallInst *Register =
- CallInst::Create(RegisterFn, FunctionContext, "",
- ContBlock->getTerminator());
- Register->setDoesNotThrow();
-
- // At this point, we are all set up. Update the invoke instructions
- // to mark their call_site values, and fill in the dispatch switch
- // accordingly.
- DenseMap<BasicBlock*,unsigned> PadSites;
- unsigned NextCallSiteValue = 1;
- for (SmallVector<InvokeInst*,16>::iterator I = Invokes.begin(),
- E = Invokes.end(); I < E; ++I) {
- unsigned CallSiteValue;
- BasicBlock *LandingPad = (*I)->getSuccessor(1);
- // landing pads can be shared. If we see a landing pad again, we
- // want to make sure to use the same call site index so the dispatch
- // will go to the right place.
- CallSiteValue = PadSites[LandingPad];
- if (!CallSiteValue) {
- CallSiteValue = NextCallSiteValue++;
- PadSites[LandingPad] = CallSiteValue;
- // Add a switch case to our unwind block. The runtime comes back
- // to the dispatcher with the call_site - 1 in the context. Odd,
- // but there it is.
- ConstantInt *SwitchValC =
- ConstantInt::get(Type::getInt32Ty((*I)->getContext()),
- CallSiteValue - 1);
- DispatchSwitch->addCase(SwitchValC, (*I)->getUnwindDest());
- }
- markInvokeCallSite(*I, CallSiteValue, CallSite);
- }
+ // Save the frame pointer.
+ Value *FramePtr = Builder.CreateConstGEP2_32(JBufPtr, 0, 0, "jbuf_fp_gep");
- // The front end has likely added calls to _Unwind_Resume. We need
- // to find those calls and mark the call_site as -1 immediately prior.
- // resume is a noreturn function, so any block that has a call to it
- // should end in an 'unreachable' instruction with the call immediately
- // prior. That's how we'll search.
- // ??? There's got to be a better way. this is fugly.
- for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB)
- if ((dyn_cast<UnreachableInst>(BB->getTerminator()))) {
- BasicBlock::iterator I = BB->getTerminator();
- // Check the previous instruction and see if it's a resume call
- if (I == BB->begin()) continue;
- if (CallInst *CI = dyn_cast<CallInst>(--I)) {
- if (CI->getCalledFunction() == ResumeFn) {
- Value *NegativeOne = Constant::getAllOnesValue(Int32Ty);
- new StoreInst(NegativeOne, CallSite, true, I); // volatile
- }
- }
+ Value *Val = Builder.CreateCall(FrameAddrFn, Builder.getInt32(0), "fp");
+ Builder.CreateStore(Val, FramePtr, /*isVolatile=*/true);
+
+ // Save the stack pointer.
+ Value *StackPtr = Builder.CreateConstGEP2_32(JBufPtr, 0, 2, "jbuf_sp_gep");
+
+ Val = Builder.CreateCall(StackAddrFn, "sp");
+ Builder.CreateStore(Val, StackPtr, /*isVolatile=*/true);
+
+ // Call the setjmp instrinsic. It fills in the rest of the jmpbuf.
+ Value *SetjmpArg = Builder.CreateBitCast(JBufPtr, Builder.getInt8PtrTy());
+ Builder.CreateCall(BuiltinSetjmpFn, SetjmpArg);
+
+ // Store a pointer to the function context so that the back-end will know
+ // where to look for it.
+ Value *FuncCtxArg = Builder.CreateBitCast(FuncCtx, Builder.getInt8PtrTy());
+ Builder.CreateCall(FuncCtxFn, FuncCtxArg);
+
+ // At this point, we are all set up, update the invoke instructions to mark
+ // their call_site values.
+ for (unsigned I = 0, E = Invokes.size(); I != E; ++I) {
+ insertCallSiteStore(Invokes[I], I + 1);
+
+ ConstantInt *CallSiteNum =
+ ConstantInt::get(Type::getInt32Ty(F.getContext()), I + 1);
+
+ // Record the call site value for the back end so it stays associated with
+ // the invoke.
+ CallInst::Create(CallSiteFn, CallSiteNum, "", Invokes[I]);
+ }
+
+ // Mark call instructions that aren't nounwind as no-action (call_site ==
+ // -1). Skip the entry block, as prior to then, no function context has been
+ // created for this function and any unexpected exceptions thrown will go
+ // directly to the caller's context, which is what we want anyway, so no need
+ // to do anything here.
+ for (Function::iterator BB = F.begin(), E = F.end(); ++BB != E;)
+ for (BasicBlock::iterator I = BB->begin(), end = BB->end(); I != end; ++I)
+ if (CallInst *CI = dyn_cast<CallInst>(I)) {
+ if (!CI->doesNotThrow())
+ insertCallSiteStore(CI, -1);
+ } else if (ResumeInst *RI = dyn_cast<ResumeInst>(I)) {
+ insertCallSiteStore(RI, -1);
}
- // Replace all unwinds with a branch to the unwind handler.
- // ??? Should this ever happen with sjlj exceptions?
- for (unsigned i = 0, e = Unwinds.size(); i != e; ++i) {
- BranchInst::Create(UnwindBlock, Unwinds[i]);
- Unwinds[i]->eraseFromParent();
- }
+ // Register the function context and make sure it's known to not throw
+ CallInst *Register = CallInst::Create(RegisterFn, FuncCtx, "",
+ EntryBB->getTerminator());
+ Register->setDoesNotThrow();
- // Scan the whole function for values that are live across unwind edges.
- // Each value that is live across an unwind edge we spill into a stack
- // location, guaranteeing that there is nothing live across the unwind
- // edge. This process also splits all critical edges coming out of
- // invoke's.
- splitLiveRangesLiveAcrossInvokes(Invokes);
-
- // Finally, for any returns from this function, if this function contains an
- // invoke, add a call to unregister the function context.
- for (unsigned i = 0, e = Returns.size(); i != e; ++i)
- CallInst::Create(UnregisterFn, FunctionContext, "", Returns[i]);
+ // Following any allocas not in the entry block, update the saved SP in the
+ // jmpbuf to the new value.
+ for (Function::iterator BB = F.begin(), E = F.end(); BB != E; ++BB) {
+ if (BB == F.begin())
+ continue;
+ for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
+ if (CallInst *CI = dyn_cast<CallInst>(I)) {
+ if (CI->getCalledFunction() != StackRestoreFn)
+ continue;
+ } else if (!isa<AllocaInst>(I)) {
+ continue;
+ }
+ Instruction *StackAddr = CallInst::Create(StackAddrFn, "sp");
+ StackAddr->insertAfter(I);
+ Instruction *StoreStackAddr = new StoreInst(StackAddr, StackPtr, true);
+ StoreStackAddr->insertAfter(StackAddr);
+ }
}
+ // Finally, for any returns from this function, if this function contains an
+ // invoke, add a call to unregister the function context.
+ for (unsigned I = 0, E = Returns.size(); I != E; ++I)
+ CallInst::Create(UnregisterFn, FuncCtx, "", Returns[I]);
+
return true;
}
-bool SjLjEHPass::runOnFunction(Function &F) {
- bool Res = insertSjLjEHSupport(F);
+bool SjLjEHPrepare::runOnFunction(Function &F) {
+ bool Res = setupEntryBlockAndCallSites(F);
return Res;
}
projects / oota-llvm.git / blobdiff