[rebranch] Revert "Cleanup unwind table emission code a bit."

llvm/include/llvm/CodeGen/MachineFunction.h

@@ -1199,6 +1199,10 @@ class LLVM_EXTERNAL_VISIBILITY MachineFunction {
   /// Find or create an LandingPadInfo for the specified MachineBasicBlock.
   LandingPadInfo &getOrCreateLandingPadInfo(MachineBasicBlock *LandingPad);
 
+  /// Remap landing pad labels and remove any deleted landing pads.
+  void tidyLandingPads(DenseMap<MCSymbol *, uintptr_t> *LPMap = nullptr,
+                       bool TidyIfNoBeginLabels = true);
+
   /// Return a reference to the landing pad info for the current function.
   const std::vector<LandingPadInfo> &getLandingPads() const {
     return LandingPads;
@@ -1214,11 +1218,22 @@ class LLVM_EXTERNAL_VISIBILITY MachineFunction {
   /// entry.
   MCSymbol *addLandingPad(MachineBasicBlock *LandingPad);
 
+  /// Provide the catch typeinfo for a landing pad.
+  void addCatchTypeInfo(MachineBasicBlock *LandingPad,
+                        ArrayRef<const GlobalValue *> TyInfo);
+
+  /// Provide the filter typeinfo for a landing pad.
+  void addFilterTypeInfo(MachineBasicBlock *LandingPad,
+                         ArrayRef<const GlobalValue *> TyInfo);
+
+  /// Add a cleanup action for a landing pad.
+  void addCleanup(MachineBasicBlock *LandingPad);
+
   /// Return the type id for the specified typeinfo.  This is function wide.
   unsigned getTypeIDFor(const GlobalValue *TI);
 
   /// Return the id of the filter encoded by TyIds.  This is function wide.
-  int getFilterIDFor(ArrayRef<unsigned> TyIds);
+  int getFilterIDFor(std::vector<unsigned> &TyIds);
 
   /// Map the landing pad's EH symbol to the call site indexes.
   void setCallSiteLandingPad(MCSymbol *Sym, ArrayRef<unsigned> Sites);

llvm/lib/CodeGen/AsmPrinter/AIXException.cpp

@@ -21,7 +21,16 @@
 
 namespace llvm {
 
-AIXException::AIXException(AsmPrinter *A) : EHStreamer(A) {}
+AIXException::AIXException(AsmPrinter *A) : DwarfCFIExceptionBase(A) {}
+
+// This overrides 'DwarfCFIExceptionBase::markFunctionEnd', to avoid the call to
+// tidyLandingPads. This is necessary, because the
+// 'PPCAIXAsmPrinter::emitFunctionBodyEnd' function already checked whether we
+// need ehinfo, and emitted a traceback table with the bits set to indicate that
+// we will be emitting it, if so. Thus, if we remove it now -- so late in the
+// process -- we'll end up having emitted a reference to __ehinfo.N symbol, but
+// not emitting a definition for said symbol.
+void AIXException::markFunctionEnd() {}
 
 void AIXException::emitExceptionInfoTable(const MCSymbol *LSDA,
                                           const MCSymbol *PerSym) {

llvm/lib/CodeGen/AsmPrinter/ARMException.cpp

@@ -19,7 +19,7 @@
 #include "llvm/MC/MCStreamer.h"
 using namespace llvm;
 
-ARMException::ARMException(AsmPrinter *A) : EHStreamer(A) {}
+ARMException::ARMException(AsmPrinter *A) : DwarfCFIExceptionBase(A) {}
 
 ARMException::~ARMException() = default;
 
@@ -51,6 +51,7 @@ void ARMException::beginFunction(const MachineFunction *MF) {
 void ARMException::markFunctionEnd() {
   if (shouldEmitCFI)
     Asm->OutStreamer->emitCFIEndProc();
+  DwarfCFIExceptionBase::markFunctionEnd();
 }
 
 /// endFunction - Gather and emit post-function exception information.

llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp

@@ -23,7 +23,18 @@
 #include "llvm/Target/TargetOptions.h"
 using namespace llvm;
 
-DwarfCFIException::DwarfCFIException(AsmPrinter *A) : EHStreamer(A) {}
+DwarfCFIExceptionBase::DwarfCFIExceptionBase(AsmPrinter *A) : EHStreamer(A) {}
+
+void DwarfCFIExceptionBase::markFunctionEnd() {
+  // Map all labels and get rid of any dead landing pads.
+  if (!Asm->MF->getLandingPads().empty()) {
+    MachineFunction *NonConstMF = const_cast<MachineFunction*>(Asm->MF);
+    NonConstMF->tidyLandingPads();
+  }
+}
+
+DwarfCFIException::DwarfCFIException(AsmPrinter *A)
+    : DwarfCFIExceptionBase(A) {}
 
 DwarfCFIException::~DwarfCFIException() = default;
 

llvm/lib/CodeGen/AsmPrinter/DwarfException.h

@@ -21,7 +21,19 @@ namespace llvm {
 class MachineFunction;
 class ARMTargetStreamer;
 
-class LLVM_LIBRARY_VISIBILITY DwarfCFIException : public EHStreamer {
+class LLVM_LIBRARY_VISIBILITY DwarfCFIExceptionBase : public EHStreamer {
+protected:
+  DwarfCFIExceptionBase(AsmPrinter *A);
+
+  /// Per-function flag to indicate if frame CFI info should be emitted.
+  bool shouldEmitCFI = false;
+  /// Per-module flag to indicate if .cfi_section has beeen emitted.
+  bool hasEmittedCFISections = false;
+
+  void markFunctionEnd() override;
+};
+
+class LLVM_LIBRARY_VISIBILITY DwarfCFIException : public DwarfCFIExceptionBase {
   /// Per-function flag to indicate if .cfi_personality should be emitted.
   bool shouldEmitPersonality = false;
 
@@ -63,13 +75,7 @@ class LLVM_LIBRARY_VISIBILITY DwarfCFIException : public EHStreamer {
   void endBasicBlockSection(const MachineBasicBlock &MBB) override;
 };
 
-class LLVM_LIBRARY_VISIBILITY ARMException : public EHStreamer {
-  /// Per-function flag to indicate if frame CFI info should be emitted.
-  bool shouldEmitCFI = false;
-
-  /// Per-module flag to indicate if .cfi_section has beeen emitted.
-  bool hasEmittedCFISections = false;
-
+class LLVM_LIBRARY_VISIBILITY ARMException : public DwarfCFIExceptionBase {
   void emitTypeInfos(unsigned TTypeEncoding, MCSymbol *TTBaseLabel) override;
   ARMTargetStreamer &getTargetStreamer();
 
@@ -93,14 +99,16 @@ class LLVM_LIBRARY_VISIBILITY ARMException : public EHStreamer {
   void markFunctionEnd() override;
 };
 
-class LLVM_LIBRARY_VISIBILITY AIXException : public EHStreamer {
+class LLVM_LIBRARY_VISIBILITY AIXException : public DwarfCFIExceptionBase {
   /// This is AIX's compat unwind section, which unwinder would use
   /// to find the location of LSDA area and personality rountine.
   void emitExceptionInfoTable(const MCSymbol *LSDA, const MCSymbol *PerSym);
 
 public:
   AIXException(AsmPrinter *A);
 
+  void markFunctionEnd() override;
+
   void endModule() override {}
   void beginFunction(const MachineFunction *MF) override {}
   void endFunction(const MachineFunction *MF) override;

llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp

@@ -194,12 +194,6 @@ void EHStreamer::computePadMap(
     const LandingPadInfo *LandingPad = LandingPads[i];
     for (unsigned j = 0, E = LandingPad->BeginLabels.size(); j != E; ++j) {
       MCSymbol *BeginLabel = LandingPad->BeginLabels[j];
-      MCSymbol *EndLabel = LandingPad->BeginLabels[j];
-      // If we have deleted the code for a given invoke after registering it in
-      // the LandingPad label list, the associated symbols will not have been
-      // emitted. In that case, ignore this callsite entry.
-      if (!BeginLabel->isDefined() || !EndLabel->isDefined())
-        continue;
       assert(!PadMap.count(BeginLabel) && "Duplicate landing pad labels!");
       PadRange P = { i, j };
       PadMap[BeginLabel] = P;
@@ -388,14 +382,8 @@ MCSymbol *EHStreamer::emitExceptionTable() {
   SmallVector<const LandingPadInfo *, 64> LandingPads;
   LandingPads.reserve(PadInfos.size());
 
-  for (const LandingPadInfo &LPI : PadInfos) {
-    // If a landing-pad has an associated label, but the label wasn't ever
-    // emitted, then skip it.  (This can occur if the landingpad's MBB was
-    // deleted).
-    if (LPI.LandingPadLabel && !LPI.LandingPadLabel->isDefined())
-      continue;
+  for (const LandingPadInfo &LPI : PadInfos)
     LandingPads.push_back(&LPI);
-  }
 
   // Order landing pads lexicographically by type id.
   llvm::sort(LandingPads, [](const LandingPadInfo *L, const LandingPadInfo *R) {

llvm/lib/CodeGen/AsmPrinter/WasmException.cpp

@@ -42,6 +42,16 @@ void WasmException::endModule() {
   }
 }
 
+void WasmException::markFunctionEnd() {
+  // Get rid of any dead landing pads.
+  if (!Asm->MF->getLandingPads().empty()) {
+    auto *NonConstMF = const_cast<MachineFunction *>(Asm->MF);
+    // Wasm does not set BeginLabel and EndLabel information for landing pads,
+    // so we should set the second argument false.
+    NonConstMF->tidyLandingPads(nullptr, /* TidyIfNoBeginLabels */ false);
+  }
+}
+
 void WasmException::endFunction(const MachineFunction *MF) {
   bool ShouldEmitExceptionTable = false;
   for (const LandingPadInfo &Info : MF->getLandingPads()) {

llvm/lib/CodeGen/AsmPrinter/WasmException.h

@@ -28,6 +28,7 @@ class LLVM_LIBRARY_VISIBILITY WasmException : public EHStreamer {
 
   void endModule() override;
   void beginFunction(const MachineFunction *MF) override {}
+  void markFunctionEnd() override;
   void endFunction(const MachineFunction *MF) override;
 
 protected:

llvm/lib/CodeGen/AsmPrinter/WinException.cpp

@@ -130,6 +130,14 @@ void WinException::endFunction(const MachineFunction *MF) {
   if (F.hasPersonalityFn())
     Per = classifyEHPersonality(F.getPersonalityFn()->stripPointerCasts());
 
+  // Get rid of any dead landing pads if we're not using funclets. In funclet
+  // schemes, the landing pad is not actually reachable. It only exists so
+  // that we can emit the right table data.
+  if (!isFuncletEHPersonality(Per)) {
+    MachineFunction *NonConstMF = const_cast<MachineFunction*>(MF);
+    NonConstMF->tidyLandingPads();
+  }
+
   endFuncletImpl();
 
   // endFunclet will emit the necessary .xdata tables for table-based SEH.

llvm/lib/CodeGen/MachineFunction.cpp

@@ -799,31 +799,32 @@ MCSymbol *MachineFunction::addLandingPad(MachineBasicBlock *LandingPad) {
     if (LPI->isCleanup() && LPI->getNumClauses() != 0)
       LP.TypeIds.push_back(0);
 
+    if (LPI->isCleanup())
+      addCleanup(LandingPad);
+
     // FIXME: New EH - Add the clauses in reverse order. This isn't 100%
     //        correct, but we need to do it this way because of how the DWARF EH
     //        emitter processes the clauses.
     for (unsigned I = LPI->getNumClauses(); I != 0; --I) {
       Value *Val = LPI->getClause(I - 1);
       if (LPI->isCatch(I - 1)) {
-        LP.TypeIds.push_back(
-            getTypeIDFor(dyn_cast<GlobalValue>(Val->stripPointerCasts())));
+        addCatchTypeInfo(LandingPad,
+                         dyn_cast<GlobalValue>(Val->stripPointerCasts()));
       } else {
         // Add filters in a list.
         auto *CVal = cast<Constant>(Val);
-        SmallVector<unsigned, 4> FilterList;
+        SmallVector<const GlobalValue *, 4> FilterList;
         for (const Use &U : CVal->operands())
-          FilterList.push_back(
-              getTypeIDFor(cast<GlobalValue>(U->stripPointerCasts())));
+          FilterList.push_back(cast<GlobalValue>(U->stripPointerCasts()));
 
-        LP.TypeIds.push_back(getFilterIDFor(FilterList));
+        addFilterTypeInfo(LandingPad, FilterList);
       }
     }
 
   } else if (const auto *CPI = dyn_cast<CatchPadInst>(FirstI)) {
     for (unsigned I = CPI->arg_size(); I != 0; --I) {
-      auto *TypeInfo =
-          dyn_cast<GlobalValue>(CPI->getArgOperand(I - 1)->stripPointerCasts());
-      LP.TypeIds.push_back(getTypeIDFor(TypeInfo));
+      Value *TypeInfo = CPI->getArgOperand(I - 1)->stripPointerCasts();
+      addCatchTypeInfo(LandingPad, dyn_cast<GlobalValue>(TypeInfo));
     }
 
   } else {
@@ -833,6 +834,73 @@ MCSymbol *MachineFunction::addLandingPad(MachineBasicBlock *LandingPad) {
   return LandingPadLabel;
 }
 
+void MachineFunction::addCatchTypeInfo(MachineBasicBlock *LandingPad,
+                                       ArrayRef<const GlobalValue *> TyInfo) {
+  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
+  for (const GlobalValue *GV : llvm::reverse(TyInfo))
+    LP.TypeIds.push_back(getTypeIDFor(GV));
+}
+
+void MachineFunction::addFilterTypeInfo(MachineBasicBlock *LandingPad,
+                                        ArrayRef<const GlobalValue *> TyInfo) {
+  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
+  std::vector<unsigned> IdsInFilter(TyInfo.size());
+  for (unsigned I = 0, E = TyInfo.size(); I != E; ++I)
+    IdsInFilter[I] = getTypeIDFor(TyInfo[I]);
+  LP.TypeIds.push_back(getFilterIDFor(IdsInFilter));
+}
+
+void MachineFunction::tidyLandingPads(DenseMap<MCSymbol *, uintptr_t> *LPMap,
+                                      bool TidyIfNoBeginLabels) {
+  for (unsigned i = 0; i != LandingPads.size(); ) {
+    LandingPadInfo &LandingPad = LandingPads[i];
+    if (LandingPad.LandingPadLabel &&
+        !LandingPad.LandingPadLabel->isDefined() &&
+        (!LPMap || (*LPMap)[LandingPad.LandingPadLabel] == 0))
+      LandingPad.LandingPadLabel = nullptr;
+
+    // Special case: we *should* emit LPs with null LP MBB. This indicates
+    // "nounwind" case.
+    if (!LandingPad.LandingPadLabel && LandingPad.LandingPadBlock) {
+      LandingPads.erase(LandingPads.begin() + i);
+      continue;
+    }
+
+    if (TidyIfNoBeginLabels) {
+      for (unsigned j = 0, e = LandingPads[i].BeginLabels.size(); j != e; ++j) {
+        MCSymbol *BeginLabel = LandingPad.BeginLabels[j];
+        MCSymbol *EndLabel = LandingPad.EndLabels[j];
+        if ((BeginLabel->isDefined() || (LPMap && (*LPMap)[BeginLabel] != 0)) &&
+            (EndLabel->isDefined() || (LPMap && (*LPMap)[EndLabel] != 0)))
+          continue;
+
+        LandingPad.BeginLabels.erase(LandingPad.BeginLabels.begin() + j);
+        LandingPad.EndLabels.erase(LandingPad.EndLabels.begin() + j);
+        --j;
+        --e;
+      }
+
+      // Remove landing pads with no try-ranges.
+      if (LandingPads[i].BeginLabels.empty()) {
+        LandingPads.erase(LandingPads.begin() + i);
+        continue;
+      }
+    }
+
+    // If there is no landing pad, ensure that the list of typeids is empty.
+    // If the only typeid is a cleanup, this is the same as having no typeids.
+    if (!LandingPad.LandingPadBlock ||
+        (LandingPad.TypeIds.size() == 1 && !LandingPad.TypeIds[0]))
+      LandingPad.TypeIds.clear();
+    ++i;
+  }
+}
+
+void MachineFunction::addCleanup(MachineBasicBlock *LandingPad) {
+  LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
+  LP.TypeIds.push_back(0);
+}
+
 void MachineFunction::setCallSiteLandingPad(MCSymbol *Sym,
                                             ArrayRef<unsigned> Sites) {
   LPadToCallSiteMap[Sym].append(Sites.begin(), Sites.end());
@@ -846,7 +914,7 @@ unsigned MachineFunction::getTypeIDFor(const GlobalValue *TI) {
   return TypeInfos.size();
 }
 
-int MachineFunction::getFilterIDFor(ArrayRef<unsigned> TyIds) {
+int MachineFunction::getFilterIDFor(std::vector<unsigned> &TyIds) {
   // If the new filter coincides with the tail of an existing filter, then
   // re-use the existing filter.  Folding filters more than this requires
   // re-ordering filters and/or their elements - probably not worth it.

llvm/test/CodeGen/X86/gcc_except_table_bb_sections.ll

@@ -148,7 +148,7 @@ declare i32 @__gxx_personality_v0(...)
 ; CHECK-NEXT:           .uleb128 .Ltmp0-.Lfunc_begin0   # >> Call Site 1 <<
 ; CHECK-NEXT:           .uleb128 .Ltmp1-.Ltmp0          #   Call between .Ltmp0 and .Ltmp1
 ; CHECK-NEXT:           .uleb128 .Ltmp2-main.__part.2   #     jumps to .Ltmp2
-; CHECK-NEXT:           .byte	3                       #   On action: 2
+; CHECK-NEXT:           .byte	5                       #   On action: 3
 ; CHECK-NEXT:           .p2align	2
 ; CHECK-NEXT:         .Lexception1:
 
@@ -207,9 +207,12 @@ declare i32 @__gxx_personality_v0(...)
 ; CHECK-NEXT:           .byte	0                       # >> Action Record 1 <<
 ; CHECK-NEXT:                                           #   Cleanup
 ; CHECK-NEXT:           .byte	0                       #   No further actions
-; CHECK-NEXT:           .byte	1                       # >> Action Record 2 <<
-; CHECK-NEXT:                                           #   Catch TypeInfo 1
-; CHECK-NEXT:           .byte	125                     #   Continue to action 1
+; CHECK-NEXT:           .byte	0                       # >> Action Record 2 <<
+; CHECK-NEXT:                                           #   Cleanup
+; CHECK-NEXT:           .byte 125                     # Continue to action 1
+; CHECK-NEXT:           .byte	1                       # >> Action Record 3 <<
+; CHECK-NEXT:                                           # Catch TypeInfo 1
+; CHECK-NEXT:           .byte 125                     # Continue to action 2
 ; CHECK-NEXT:           .p2align 2
 ; CHECK-NEXT:                                           # >> Catch TypeInfos <<
 

llvm/test/CodeGen/X86/gcc_except_table_bb_sections_ehpad_groups_with_cold.ll

@@ -66,7 +66,7 @@ declare i32 @__gxx_personality_v0(...)
 ; CHECK-NEXT:    .uleb128 .Ltmp0-.Lfunc_begin0  # >> Call Site 1 <<
 ; CHECK-NEXT:    .uleb128 .Ltmp1-.Ltmp0         #   Call between .Ltmp0 and .Ltmp1
 ; CHECK-NEXT:    .uleb128 .Ltmp2-main.cold      #     jumps to .Ltmp2
-; CHECK-NEXT:    .byte	3                       #   On action: 2
+; CHECK-NEXT:    .byte	5                       #   On action: 3
 ; CHECK-NEXT:    .p2align	2
 ; CHECK-NEXT:  .Lexception1:
 ; CHECK-NEXT:    .byte	0                       # @LPStart Encoding = absptr
@@ -85,9 +85,12 @@ declare i32 @__gxx_personality_v0(...)
 ; CHECK-NEXT:    .byte	0                       # >> Action Record 1 <<
 ; CHECK-NEXT:                                   #   Cleanup
 ; CHECK-NEXT:    .byte	0                       #   No further actions
-; CHECK-NEXT:    .byte	1                       # >> Action Record 2 <<
-; CHECK-NEXT:                                   #   Catch TypeInfo 1
+; CHECK-NEXT:    .byte	0                       # >> Action Record 2 <<
+; CHECK-NEXT:                                   #   Cleanup
 ; CHECK-NEXT:    .byte	125                     #   Continue to action 1
+; CHECK-NEXT:    .byte  1                       # >> Action Record 3 <<
+; CHECK-NEXT:                                   #   Catch TypeInfo 1
+; CHECK-NEXT:    .byte	125                     #   Continue to action 2
 ; CHECK-NEXT:    .p2align	2
 ; CHECK-NEXT:                                   # >> Catch TypeInfos <<
 ; CHECK-NEXT:    .long	_ZTIi                   # TypeInfo 1