[WinEH] Try to make the MachineFunction CFG more accurate
This avoids emitting code for unreachable landingpad blocks that contain
calls to llvm.eh.actions and indirectbr.
It's also a first step towards unifying the SEH and WinEH lowering
codepaths. I'm keeping the old fan-in lowering of SEH around until the
preparation version works well enough that we can switch over without
breaking existing users.
llvm-svn: 235037
diff --git a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 4ff0b9f..1e116dd 100644
--- a/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -933,53 +933,74 @@
const LandingPadInst *LPadInst = LLVMBB->getLandingPadInst();
MF->getMMI().addPersonality(
MBB, cast<Function>(LPadInst->getPersonalityFn()->stripPointerCasts()));
- if (MF->getMMI().getPersonalityType() == EHPersonality::MSVC_Win64SEH) {
- // Make virtual registers and a series of labels that fill in values for the
- // clauses.
- auto &RI = MF->getRegInfo();
- FuncInfo->ExceptionSelectorVirtReg = RI.createVirtualRegister(PtrRC);
+ EHPersonality Personality = MF->getMMI().getPersonalityType();
- // Get all invoke BBs that will unwind into the clause BBs.
+ if (isMSVCEHPersonality(Personality)) {
+ SmallVector<MachineBasicBlock *, 4> ClauseBBs;
+ const IntrinsicInst *Actions =
+ dyn_cast<IntrinsicInst>(LLVMBB->getFirstInsertionPt());
+ // Get all invoke BBs that unwind to this landingpad.
SmallVector<MachineBasicBlock *, 4> InvokeBBs(MBB->pred_begin(),
MBB->pred_end());
+ if (Actions && Actions->getIntrinsicID() == Intrinsic::eh_actions) {
+ // If this is a call to llvm.eh.actions followed by indirectbr, then we've
+ // run WinEHPrepare, and we should remove this block from the machine CFG.
+ // Mark the targets of the indirectbr as landingpads instead.
+ for (const BasicBlock *LLVMSucc : successors(LLVMBB)) {
+ MachineBasicBlock *ClauseBB = FuncInfo->MBBMap[LLVMSucc];
+ // Add the edge from the invoke to the clause.
+ for (MachineBasicBlock *InvokeBB : InvokeBBs)
+ InvokeBB->addSuccessor(ClauseBB);
+ }
+ } else {
+ // Otherwise, we haven't done the preparation, and we need to invent some
+ // clause basic blocks that branch into the landingpad.
+ // FIXME: Remove this code once SEH preparation works.
- // Emit separate machine basic blocks with separate labels for each clause
- // before the main landing pad block.
- MachineInstrBuilder SelectorPHI = BuildMI(
- *MBB, MBB->begin(), SDB->getCurDebugLoc(), TII->get(TargetOpcode::PHI),
- FuncInfo->ExceptionSelectorVirtReg);
- for (unsigned I = 0, E = LPadInst->getNumClauses(); I != E; ++I) {
- // Skip filter clauses, we can't implement them yet.
- if (LPadInst->isFilter(I))
- continue;
+ // Make virtual registers and a series of labels that fill in values for
+ // the clauses.
+ auto &RI = MF->getRegInfo();
+ FuncInfo->ExceptionSelectorVirtReg = RI.createVirtualRegister(PtrRC);
- MachineBasicBlock *ClauseBB = MF->CreateMachineBasicBlock(LLVMBB);
- MF->insert(MBB, ClauseBB);
+ // Emit separate machine basic blocks with separate labels for each clause
+ // before the main landing pad block.
+ MachineInstrBuilder SelectorPHI = BuildMI(
+ *MBB, MBB->begin(), SDB->getCurDebugLoc(),
+ TII->get(TargetOpcode::PHI), FuncInfo->ExceptionSelectorVirtReg);
+ for (unsigned I = 0, E = LPadInst->getNumClauses(); I != E; ++I) {
+ // Skip filter clauses, we can't implement them.
+ if (LPadInst->isFilter(I))
+ continue;
- // Add the edge from the invoke to the clause.
- for (MachineBasicBlock *InvokeBB : InvokeBBs)
- InvokeBB->addSuccessor(ClauseBB);
+ MachineBasicBlock *ClauseBB = MF->CreateMachineBasicBlock(LLVMBB);
+ MF->insert(MBB, ClauseBB);
- // Mark the clause as a landing pad or MI passes will delete it.
- ClauseBB->setIsLandingPad();
+ // Add the edge from the invoke to the clause.
+ for (MachineBasicBlock *InvokeBB : InvokeBBs)
+ InvokeBB->addSuccessor(ClauseBB);
- GlobalValue *ClauseGV = ExtractTypeInfo(LPadInst->getClause(I));
+ // Mark the clause as a landing pad or MI passes will delete it.
+ ClauseBB->setIsLandingPad();
- // Start the BB with a label.
- MCSymbol *ClauseLabel = MF->getMMI().addClauseForLandingPad(MBB);
- BuildMI(*ClauseBB, ClauseBB->begin(), SDB->getCurDebugLoc(), II)
- .addSym(ClauseLabel);
+ GlobalValue *ClauseGV = ExtractTypeInfo(LPadInst->getClause(I));
- // Construct a simple BB that defines a register with the typeid constant.
- FuncInfo->MBB = ClauseBB;
- FuncInfo->InsertPt = ClauseBB->end();
- unsigned VReg = SDB->visitLandingPadClauseBB(ClauseGV, MBB);
- CurDAG->setRoot(SDB->getRoot());
- SDB->clear();
- CodeGenAndEmitDAG();
+ // Start the BB with a label.
+ MCSymbol *ClauseLabel = MF->getMMI().addClauseForLandingPad(MBB);
+ BuildMI(*ClauseBB, ClauseBB->begin(), SDB->getCurDebugLoc(), II)
+ .addSym(ClauseLabel);
- // Add the typeid virtual register to the phi in the main landing pad.
- SelectorPHI.addReg(VReg).addMBB(ClauseBB);
+ // Construct a simple BB that defines a register with the typeid
+ // constant.
+ FuncInfo->MBB = ClauseBB;
+ FuncInfo->InsertPt = ClauseBB->end();
+ unsigned VReg = SDB->visitLandingPadClauseBB(ClauseGV, MBB);
+ CurDAG->setRoot(SDB->getRoot());
+ SDB->clear();
+ CodeGenAndEmitDAG();
+
+ // Add the typeid virtual register to the phi in the main landing pad.
+ SelectorPHI.addReg(VReg).addMBB(ClauseBB);
+ }
}
// Remove the edge from the invoke to the lpad.
@@ -990,12 +1011,14 @@
// pad block.
FuncInfo->MBB = MBB;
FuncInfo->InsertPt = MBB->end();
+
+ // Transfer EH state number assigned to the IR block to the MBB.
+ if (Personality == EHPersonality::MSVC_CXX) {
+ WinEHFuncInfo &FI = MF->getMMI().getWinEHFuncInfo(MF->getFunction());
+ MF->getMMI().addWinEHState(MBB, FI.LandingPadStateMap[LPadInst]);
+ }
return;
}
- if (MF->getMMI().getPersonalityType() == EHPersonality::MSVC_CXX) {
- WinEHFuncInfo &FuncInfo = MF->getMMI().getWinEHFuncInfo(MF->getFunction());
- MF->getMMI().addWinEHState(MBB, FuncInfo.LandingPadStateMap[LPadInst]);
- }
// Mark exception register as live in.
if (unsigned Reg = TLI->getExceptionPointerRegister())
@@ -1173,7 +1196,7 @@
// Setup an EH landing-pad block.
FuncInfo->ExceptionPointerVirtReg = 0;
FuncInfo->ExceptionSelectorVirtReg = 0;
- if (FuncInfo->MBB->isLandingPad())
+ if (LLVMBB->isLandingPad())
PrepareEHLandingPad();
// Before doing SelectionDAG ISel, see if FastISel has been requested.