[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.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@235037 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/CodeGen/AsmPrinter/Win64Exception.cpp b/lib/CodeGen/AsmPrinter/Win64Exception.cpp
index 0d422d83e2d372b439b1dcf676ca8a0954c8766e..f89d36455f415e8191d796045a056cf11839ec21 100644 (file)
--- a/lib/CodeGen/AsmPrinter/Win64Exception.cpp
+++ b/lib/CodeGen/AsmPrinter/Win64Exception.cpp
@@ -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)

diff --git a/lib/CodeGen/MachineModuleInfo.cpp b/lib/CodeGen/MachineModuleInfo.cpp
index d5491213293f259c4ab8cb9baf6949d151627c14..e8bd1f8e6d9cae8e76dc04e625f659532f8fcc72 100644 (file)
--- a/lib/CodeGen/MachineModuleInfo.cpp
+++ b/lib/CodeGen/MachineModuleInfo.cpp
@@ -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 {

diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
index 4ff0b9fefcb861ae64b4a27dfb8ef486c937f473..1e116dddafaaef73853c16530569f0158f682289 100644 (file)
--- a/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
+++ b/lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp
@@ -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.
+
+      // Make virtual registers and a series of labels that fill in values for
+      // the clauses.
+      auto &RI = MF->getRegInfo();
+      FuncInfo->ExceptionSelectorVirtReg = RI.createVirtualRegister(PtrRC);
+
+      // 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;
 
-    // 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;
-
-      MachineBasicBlock *ClauseBB = MF->CreateMachineBasicBlock(LLVMBB);
-      MF->insert(MBB, ClauseBB);
+        MachineBasicBlock *ClauseBB = MF->CreateMachineBasicBlock(LLVMBB);
+        MF->insert(MBB, ClauseBB);
 
-      // Add the edge from the invoke to the clause.
-      for (MachineBasicBlock *InvokeBB : InvokeBBs)
-        InvokeBB->addSuccessor(ClauseBB);
+        // Add the edge from the invoke to the clause.
+        for (MachineBasicBlock *InvokeBB : InvokeBBs)
+          InvokeBB->addSuccessor(ClauseBB);
 
-      // Mark the clause as a landing pad or MI passes will delete it.
-      ClauseBB->setIsLandingPad();
+        // Mark the clause as a landing pad or MI passes will delete it.
+        ClauseBB->setIsLandingPad();
 
-      GlobalValue *ClauseGV = ExtractTypeInfo(LPadInst->getClause(I));
+        GlobalValue *ClauseGV = ExtractTypeInfo(LPadInst->getClause(I));
 
-      // Start the BB with a label.
-      MCSymbol *ClauseLabel = MF->getMMI().addClauseForLandingPad(MBB);
-      BuildMI(*ClauseBB, ClauseBB->begin(), SDB->getCurDebugLoc(), II)
-          .addSym(ClauseLabel);
+        // Start the BB with a label.
+        MCSymbol *ClauseLabel = MF->getMMI().addClauseForLandingPad(MBB);
+        BuildMI(*ClauseBB, ClauseBB->begin(), SDB->getCurDebugLoc(), II)
+            .addSym(ClauseLabel);
 
-      // 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();
+        // 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);
+        // 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.

diff --git a/test/CodeGen/WinEH/cppeh-prepared-catch.ll b/test/CodeGen/WinEH/cppeh-prepared-catch.ll
index 7c53085edc55746a059a2db3b691bc02a2eca8c7..0adbb8e8296e4cf547ad65bc64882981ff68617e 100644 (file)
--- a/test/CodeGen/WinEH/cppeh-prepared-catch.ll
+++ b/test/CodeGen/WinEH/cppeh-prepared-catch.ll
@@ -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":