- // 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);
- }