diff options
| -rw-r--r-- | lib/CodeGen/SjLjEHPrepare.cpp | 59 |
1 files changed, 44 insertions, 15 deletions
diff --git a/lib/CodeGen/SjLjEHPrepare.cpp b/lib/CodeGen/SjLjEHPrepare.cpp index ed02025512..2a7a7cdc3c 100644 --- a/lib/CodeGen/SjLjEHPrepare.cpp +++ b/lib/CodeGen/SjLjEHPrepare.cpp @@ -71,6 +71,7 @@ namespace { void markInvokeCallSite(InvokeInst *II, int InvokeNo, Value *CallSite, SwitchInst *CatchSwitch); void splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes); + void splitLandingPad(InvokeInst *II); bool insertSjLjEHSupport(Function &F); }; } // end anonymous namespace @@ -130,6 +131,42 @@ void SjLjEHPass::insertCallSiteStore(Instruction *I, int Number, new StoreInst(CallSiteNoC, CallSite, true, I); // volatile } +/// splitLandingPad - Split a landing pad. This takes considerable care because +/// of PHIs and other nasties. The problem is that the jump table needs to jump +/// to the landing pad block. However, the landing pad block can be jumped to +/// only by an invoke instruction. So we clone the landingpad instruction into +/// its own basic block, have the invoke jump to there. The landingpad +/// instruction's basic block's successor is now the target for the jump table. +/// +/// But because of PHI nodes, we need to create another basic block for the jump +/// table to jump to. This is definitely a hack, because the values for the PHI +/// nodes may not be defined on the edge from the jump table. But that's okay, +/// because the jump table is simply a construct to mimic what is happening in +/// the CFG. So the values are mysteriously there, even though there is no value +/// for the PHI from the jump table's edge (hence calling this a hack). +void SjLjEHPass::splitLandingPad(InvokeInst *II) { + SmallVector<BasicBlock*, 2> NewBBs; + SplitLandingPadPredecessors(II->getUnwindDest(), II->getParent(), + ".1", ".2", this, NewBBs); + + // Create an empty block so that the jump table has something to jump to + // which doesn't have any PHI nodes. + BasicBlock *LPad = NewBBs[0]; + BasicBlock *Succ = *succ_begin(LPad); + BasicBlock *JumpTo = BasicBlock::Create(II->getContext(), "jt.land", + LPad->getParent(), Succ); + LPad->getTerminator()->eraseFromParent(); + BranchInst::Create(JumpTo, LPad); + BranchInst::Create(Succ, JumpTo); + LPadSuccMap[II] = JumpTo; + + for (BasicBlock::iterator I = Succ->begin(); isa<PHINode>(I); ++I) { + PHINode *PN = cast<PHINode>(I); + Value *Val = PN->removeIncomingValue(LPad, false); + PN->addIncoming(Val, JumpTo); + } +} + /// markInvokeCallSite - Insert code to mark the call_site for this invoke void SjLjEHPass::markInvokeCallSite(InvokeInst *II, int InvokeNo, Value *CallSite, @@ -139,19 +176,15 @@ void SjLjEHPass::markInvokeCallSite(InvokeInst *II, int InvokeNo, // 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(II->getContext()), - InvokeNo - 1); + InvokeNo - 1); // If the unwind edge has phi nodes, split the edge. if (isa<PHINode>(II->getUnwindDest()->begin())) { // FIXME: New EH - This if-condition will be always true in the new scheme. - if (II->getUnwindDest()->isLandingPad()) { - SmallVector<BasicBlock*, 2> NewBBs; - SplitLandingPadPredecessors(II->getUnwindDest(), II->getParent(), - ".1", ".2", this, NewBBs); - LPadSuccMap[II] = *succ_begin(NewBBs[0]); - } else { + if (II->getUnwindDest()->isLandingPad()) + splitLandingPad(II); + else 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())) { @@ -201,14 +234,10 @@ splitLiveRangesAcrossInvokes(SmallVector<InvokeInst*,16> &Invokes) { SplitCriticalEdge(II, 0, this); // FIXME: New EH - This if-condition will be always true in the new scheme. - if (II->getUnwindDest()->isLandingPad()) { - SmallVector<BasicBlock*, 2> NewBBs; - SplitLandingPadPredecessors(II->getUnwindDest(), II->getParent(), - ".1", ".2", this, NewBBs); - LPadSuccMap[II] = *succ_begin(NewBBs[0]); - } else { + if (II->getUnwindDest()->isLandingPad()) + splitLandingPad(II); + else SplitCriticalEdge(II, 1, this); - } assert(!isa<PHINode>(II->getNormalDest()) && !isa<PHINode>(II->getUnwindDest()) && |