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[WinEH] Try to make the MachineFunction CFG more accurate

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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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235037 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Reid Kleckner 2015-04-15 18:48:15 +00:00
parent a1c91277c4
commit 192537c4f3
4 changed files with 82 additions and 46 deletions
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10
lib/CodeGen/AsmPrinter/Win64Exception.cpp
View File

@ -108,8 +108,13 @@ void Win64Exception::endFunction(const MachineFunction *MF) {
if (!shouldEmitPersonality && !shouldEmitMoves)
return;
// Map all labels and get rid of any dead landing pads.
MMI->TidyLandingPads();
EHPersonality Per = MMI->getPersonalityType();
// Get rid of any dead landing pads if we're not using a Windows EH scheme. In
// Windows EH schemes, the landing pad is not actually reachable. It only
// exists so that we can emit the right table data.
if (!isMSVCEHPersonality(Per))
MMI->TidyLandingPads();
if (shouldEmitPersonality) {
Asm->OutStreamer.PushSection();
@ -119,7 +124,6 @@ void Win64Exception::endFunction(const MachineFunction *MF) {
// Emit the tables appropriate to the personality function in use. If we
// don't recognize the personality, assume it uses an Itanium-style LSDA.
EHPersonality Per = MMI->getPersonalityType();
if (Per == EHPersonality::MSVC_Win64SEH)
emitCSpecificHandlerTable();
else if (Per == EHPersonality::MSVC_CXX)

7
lib/CodeGen/MachineModuleInfo.cpp
View File

@ -570,10 +570,13 @@ const Function *MachineModuleInfo::getPersonality() const {
}
EHPersonality MachineModuleInfo::getPersonalityType() {
if (PersonalityTypeCache == EHPersonality::Unknown)
PersonalityTypeCache = classifyEHPersonality(getPersonality());
if (PersonalityTypeCache == EHPersonality::Unknown) {
if (const Function *F = getPersonality())
PersonalityTypeCache = classifyEHPersonality(F);
}
return PersonalityTypeCache;
}
/// getPersonalityIndex - Return unique index for current personality
/// function. NULL/first personality function should always get zero index.
unsigned MachineModuleInfo::getPersonalityIndex() const {

105
lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
View File

@ -933,53 +933,74 @@ void SelectionDAGISel::PrepareEHLandingPad() {
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 @@ void SelectionDAGISel::PrepareEHLandingPad() {
// 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 @@ void SelectionDAGISel::SelectAllBasicBlocks(const Function &Fn) {
// 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.

6
test/CodeGen/WinEH/cppeh-prepared-catch.ll
View File

@ -50,6 +50,8 @@ lpad1: ; preds = %entry
}
; CHECK-LABEL: "?f@@YAXXZ.catch":
; No code should be generated for the indirectbr.
; CHECK-NOT: jmpq *
; CHECK: .seh_handlerdata
; CHECK: .long ("$cppxdata$?f@@YAXXZ")@IMGREL
@ -72,6 +74,8 @@ lpad: ; preds = %entry
}
; CHECK-LABEL: "?f@@YAXXZ.catch1":
; No code should be generated for the indirectbr.
; CHECK-NOT: jmpq *
; CHECK: ".L?f@@YAXXZ.catch1$parent_frame_offset" = 16
; CHECK: movq %rdx, 16(%rsp)
; CHECK: .seh_handlerdata
@ -112,6 +116,8 @@ try.cont8: ; preds = %lpad2, %try.cont
}
; CHECK-LABEL: "?f@@YAXXZ":
; No code should be generated for the indirectbr.
; CHECK-NOT: jmpq *
; CHECK: .seh_handlerdata
; CHECK-NEXT: .long ("$cppxdata$?f@@YAXXZ")@IMGREL
; CHECK-NEXT:"$cppxdata$?f@@YAXXZ":