[WebAssembly] LSDA info generation

[aheejin]

Summary

This adds support for LSDA (exception table) generation for wasm EH.
Wasm EH mostly follows the structure of Itanium-style exception tables,
with one exception: a call site table entry in wasm EH corresponds to
not a call site but a landing pad.

In wasm EH, the VM is responsible for stack unwinding. After an
exception occurs and the stack is unwound, the control flow is
transferred to wasm 'catch' instruction by the VM, after which the
personality function is called from the compiler-generated code. (Refer
to WasmEHPrepare pass for more information on this part.)

This patch:

• Changes wasm.landingpad.index intrinsic to take a token argument, to make this 1:1 match with a catchpad instruction
• Stores landingpad index info and catch type info MachineFunction in before instruction selection
• Lowers wasm.lsda intrinsic to an MCSymbol pointing to the start of an exception table
• Adds WasmException class with overridden methods for table generation
• Adds support for LSDA section in Wasm object writer

[aheejin]

Fix encoding

[aheejin]

• Add comment

[aheejin]

Fix comments

[sbc100]

lib/CodeGen/AsmPrinter/EHStreamer.cpp

610

This seems a little off, could remove that requirement?

If we can't then perhaps invert this check we we only have a single return statement?

if (!IsWasm)
  Asm->EmitAlignment(2);
return GCCETSym;

test/CodeGen/WebAssembly/eh-lsda.ll

45

Ha.. I didn't know that assembler could be used to encode LEBs like this.

I'm assuming this assembly value (i.e. doesn't generate a relocations?)

[aheejin]

lib/CodeGen/AsmPrinter/EHStreamer.cpp

610

Yes it seemed a little off to me :( We can remove it, but it requires more aggressive refactoring. So basically the problem is, while it is better to move wasm-specific functionalities to WasmException class like as I did for WasmException::computeCallSiteTable, wasm can completely reuse the existing emitExceptionTable, except it requires to emit something before the final alignment directive. To refactor this, we should probably split this emitExceptionTable into 2-3 different functions, and make WasmException call only relevant functions from them. What do you think? Do you think it's worth it?

test/CodeGen/WebAssembly/eh-lsda.ll

45

Yeah it doesn't generate a relocation.

[dschuff]

lib/CodeGen/AsmPrinter/WasmException.cpp

31

Can this be const LandingPadInfo& instead of const auto for more clarity?

42

Is there some particular reason for this or is it just a limitation of our assembler and/or MC?

[dschuff]

lib/CodeGen/AsmPrinter/EHStreamer.cpp

610

If it causes a lot of ugliness, there's actually no reason we need to emit the size before the alignment; it could go after. The only difference is whether the calculated size of the object includes or doesn't include the padding that the align directive might emit. (This would mean that when emit the table in the object file, the resulting segment might contain up to 3 bytes of padding on the end instead of having a gap between the segments, but that's not the end of the world).

[aheejin]

• const auto -> const LandingPadInfo&

lib/CodeGen/AsmPrinter/WasmException.cpp

42

Looks like wasm object writer & obj2yaml are structured to save sizes for data symbols. The size information is also shown in obj2yaml. I guess this info is used in the symbol table, and not elsewhere (so the final binary works without this info). We can do away with setting size for now if we really want, but I'm not sure if it's good to modify the symbol table structure, and the size info might be needed later for debug info or something..? @sbc100, what do you think?

[aheejin]

• Add original C++ code comment to test case

[aheejin]

lib/CodeGen/AsmPrinter/WasmException.cpp

42

Ping. If we agree that we shouldn't remove size info from the symbol table, I'll probably go ahead and emit the symbol after the alignment, as @dschuff said.

[sbc100]

Sorry for not replying earlier. Yes, we should generate and preserve size information for data symbols if possible.

[dschuff]

Is that information what's used/needed to allow the linker to create a separate wasm segment per global?

[sbc100]

In D52748#1259503, @dschuff wrote:

Is that information what's used/needed to allow the linker to create a separate wasm segment per global?

No, the linker operates on the input segments.. which normally map 1-to-1 with symbols (We can in theary support -fno-data-segments which would result in many symbols in a single segment, but in that case the linker cannot GC any of those symbols individually).

The size is mostly for compatibility with 'nm' and other tools that list symbols with their sizes.

[aheejin]

• Emit .size after .p2align

[dschuff]

lib/CodeGen/AsmPrinter/WasmException.h

24

I realize this naming convention is pre-existing but ༼ ༎ຶ ෴ ༎ຶ༽

[aheejin]

lib/CodeGen/AsmPrinter/WasmException.h

24

Yeah ***Exception inheriting from EHStreamer looks really confusing...

[rnk]

Looks good, I had one style comment. Glad to see this coming together. :)

lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

1170–1195

I think this code would be more readable if you factor out the body of this if into a helper and give it some name, like mapWasmLandingPadIndex(MBB, CPI). The loop to iterate over all uses is a bit complicated, but the overall effect is pretty simple.

1186

I see, so this intrinsic only exists to associate this landing pad index number with the catchpad. If we had some other way to staple the number onto catchpad, that would be nicer. This seems like an OK way to do this.

[aheejin]

lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

1186

Do you think I can put the index number in a bundle argument to catchpad? Like, a named bundle operand "index".

[aheejin]

• Factor out mapWasmLandingPadIndex

[aheejin]

lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

1186

Operand bundles seem to only can be attached to CallInst and InvokeInst, so this is not gonna work.

include/llvm/CodeGen/MachineFunction.h

class MachineFunction {
   /// \{
 
   /// List of LandingPadInfo describing the landing pad information.
   std::vector<LandingPadInfo> LandingPads;
 
   /// Map a landing pad's EH symbol to the call site indexes.
   DenseMap<MCSymbol*, SmallVector<unsigned, 4>> LPadToCallSiteMap;
 
+  /// Map a landing pad to its index.
+  DenseMap<const MachineBasicBlock *, unsigned> WasmLPadToIndexMap;
+
   /// Map of invoke call site index values to associated begin EH_LABEL.
   DenseMap<MCSymbol*, unsigned> CallSiteMap;
 
   /// CodeView label annotations.
   std::vector<std::pair<MCSymbol *, MDNode *>> CodeViewAnnotations;
 
   bool CallsEHReturn = false;
   bool CallsUnwindInit = false;
public:
 
   bool hasEHFunclets() const { return HasEHFunclets; }
   void setHasEHFunclets(bool V) { HasEHFunclets = V; }
 
   /// 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);
+  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;
   }
 
   /// Provide the begin and end labels of an invoke style call and associate it
   /// with a try landing pad block.
public:
   unsigned getTypeIDFor(const GlobalValue *TI);
 
   /// Return the id of the filter encoded by TyIds.  This is function wide.
   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);
 
+  /// Map the landing pad to its index. Used for Wasm exception handling.
+  void setWasmLandingPadIndex(const MachineBasicBlock *LPad, unsigned Index) {
+    WasmLPadToIndexMap[LPad] = Index;
+  }
+
+  /// Returns true if the landing pad has an associate index in wasm EH.
+  bool hasWasmLandingPadIndex(const MachineBasicBlock *LPad) const {
+    return WasmLPadToIndexMap.count(LPad);
+  }
+
+  /// Get the index in wasm EH for a given landing pad.
+  unsigned getWasmLandingPadIndex(const MachineBasicBlock *LPad) const {
+    assert(hasWasmLandingPadIndex(LPad));
+    return WasmLPadToIndexMap.lookup(LPad);
+  }
+
   /// Get the call site indexes for a landing pad EH symbol.
   SmallVectorImpl<unsigned> &getCallSiteLandingPad(MCSymbol *Sym) {
     assert(hasCallSiteLandingPad(Sym) &&
            "missing call site number for landing pad!");
     return LPadToCallSiteMap[Sym];
   }
 
   /// Return true if the landing pad Eh symbol has an associated call site.

include/llvm/IR/IntrinsicsWebAssembly.td

 // wasm.catch returns the pointer to the exception object caught by wasm 'catch'
 // instruction.
 def int_wasm_catch : Intrinsic<[llvm_ptr_ty], [llvm_i32_ty],
                                [IntrHasSideEffects]>;
 
 // WebAssembly EH must maintain the landingpads in the order assigned to them
 // by WasmEHPrepare pass to generate landingpad table in EHStreamer. This is
 // used in order to give them the indices in WasmEHPrepare.
-def int_wasm_landingpad_index: Intrinsic<[], [llvm_i32_ty], [IntrNoMem]>;
+def int_wasm_landingpad_index: Intrinsic<[], [llvm_token_ty, llvm_i32_ty],
+                                         [IntrNoMem]>;
 
 // Returns LSDA address of the current function.
 def int_wasm_lsda : Intrinsic<[llvm_ptr_ty], [], [IntrNoMem]>;
 
 //===----------------------------------------------------------------------===//
 // Atomic intrinsics
 //===----------------------------------------------------------------------===//
 

lib/CodeGen/AsmPrinter/AsmPrinter.cpp

 //
 //===----------------------------------------------------------------------===//
 
 #include "llvm/CodeGen/AsmPrinter.h"
 #include "AsmPrinterHandler.h"
 #include "CodeViewDebug.h"
 #include "DwarfDebug.h"
 #include "DwarfException.h"
+#include "WasmException.h"
 #include "WinCFGuard.h"
 #include "WinException.h"
 #include "llvm/ADT/APFloat.h"
 #include "llvm/ADT/APInt.h"
 #include "llvm/ADT/DenseMap.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallString.h"
case WinEH::EncodingType::Invalid:
       break;
     case WinEH::EncodingType::X86:
     case WinEH::EncodingType::Itanium:
       ES = new WinException(this);
       break;
     }
     break;
   case ExceptionHandling::Wasm:
-    // TODO to prevent warning
+    ES = new WasmException(this);
     break;
   }
   if (ES)
     Handlers.push_back(HandlerInfo(ES, EHTimerName, EHTimerDescription,
                                    DWARFGroupName, DWARFGroupDescription));
 
   if (mdconst::extract_or_null<ConstantInt>(
           MMI->getModule()->getModuleFlag("cfguardtable")))

lib/CodeGen/AsmPrinter/CMakeLists.txt

add_llvm_library(LLVMAsmPrinter
   DwarfStringPool.cpp
   DwarfUnit.cpp
   EHStreamer.cpp
   ErlangGCPrinter.cpp
   OcamlGCPrinter.cpp
   WinCFGuard.cpp
   WinException.cpp
   CodeViewDebug.cpp
+  WasmException.cpp
 
   DEPENDS
   intrinsics_gen
   )

lib/CodeGen/AsmPrinter/EHStreamer.h

void computePadMap(const SmallVectorImpl<const LandingPadInfo *> &LandingPads,
                      RangeMapType &PadMap);
 
   /// Compute the call-site table.  The entry for an invoke has a try-range
   /// containing the call, a non-zero landing pad and an appropriate action.
   /// The entry for an ordinary call has a try-range containing the call and
   /// zero for the landing pad and the action.  Calls marked 'nounwind' have
   /// no entry and must not be contained in the try-range of any entry - they
   /// form gaps in the table.  Entries must be ordered by try-range address.
-  void computeCallSiteTable(SmallVectorImpl<CallSiteEntry> &CallSites,
-                            const SmallVectorImpl<const LandingPadInfo *> &LandingPads,
-                            const SmallVectorImpl<unsigned> &FirstActions);
+  virtual void computeCallSiteTable(
+      SmallVectorImpl<CallSiteEntry> &CallSites,
 
   /// Emit landing pads and actions.
   ///
   /// The general organization of the table is complex, but the basic concepts
   /// are easy.  First there is a header which describes the location and
   /// organization of the three components that follow.
   ///  1. The landing pad site information describes the range of code covered
   ///     by the try.  In our case it's an accumulation of the ranges covered
   ///     by the invokes in the try.  There is also a reference to the landing
   ///     pad that handles the exception once processed.  Finally an index into
   ///     the actions table.
   ///  2. The action table, in our case, is composed of pairs of type ids
   ///     and next action offset.  Starting with the action index from the
   ///     landing pad site, each type Id is checked for a match to the current
   ///     exception.  If it matches then the exception and type id are passed
   ///     on to the landing pad.  Otherwise the next action is looked up.  This
   ///     chain is terminated with a next action of zero.  If no type id is
   ///     found the frame is unwound and handling continues.
   ///  3. Type id table contains references to all the C++ typeinfo for all
   ///     catches in the function.  This tables is reversed indexed base 1.
-  void emitExceptionTable();
+  ///
+  /// Returns the starting symbol of an exception table.
+  MCSymbol *emitExceptionTable();
 
   virtual void emitTypeInfos(unsigned TTypeEncoding, MCSymbol *TTBaseLabel);
 
   // Helpers for identifying what kind of clause an EH typeid or selector
   // corresponds to. Negative selectors are for filter clauses, the zero
   // selector is for cleanups, and positive selectors are for catch clauses.
   static bool isFilterEHSelector(int Selector) { return Selector < 0; }
   static bool isCleanupEHSelector(int Selector) { return Selector == 0; }

lib/CodeGen/AsmPrinter/EHStreamer.cpp

 ///     action offset.  Starting with the action index from the landing pad
 ///     site, each type ID is checked for a match to the current exception.  If
 ///     it matches then the exception and type id are passed on to the landing
 ///     pad.  Otherwise the next action is looked up.  This chain is terminated
 ///     with a next action of zero.  If no type id is found then the frame is
 ///     unwound and handling continues.
 ///  3. Type ID table contains references to all the C++ typeinfo for all
 ///     catches in the function.  This tables is reverse indexed base 1.
-void EHStreamer::emitExceptionTable() {
+///
+/// Returns the starting symbol of an exception table.
+MCSymbol *EHStreamer::emitExceptionTable() {
   const MachineFunction *MF = Asm->MF;
   const std::vector<const GlobalValue *> &TypeInfos = MF->getTypeInfos();
   const std::vector<unsigned> &FilterIds = MF->getFilterIds();
   const std::vector<LandingPadInfo> &PadInfos = MF->getLandingPads();
 
   // Sort the landing pads in order of their type ids.  This is used to fold
   // duplicate actions.
   SmallVector<const LandingPadInfo *, 64> LandingPads;
MCSymbol *EHStreamer::emitExceptionTable() {
   SmallVector<unsigned, 64> FirstActions;
   computeActionsTable(LandingPads, Actions, FirstActions);
 
   // Compute the call-site table.
   SmallVector<CallSiteEntry, 64> CallSites;
   computeCallSiteTable(CallSites, LandingPads, FirstActions);
 
   bool IsSJLJ = Asm->MAI->getExceptionHandlingType() == ExceptionHandling::SjLj;
+  bool IsWasm = Asm->MAI->getExceptionHandlingType() == ExceptionHandling::Wasm;
   unsigned CallSiteEncoding =
       IsSJLJ ? dwarf::DW_EH_PE_udata4 : dwarf::DW_EH_PE_uleb128;
   bool HaveTTData = !TypeInfos.empty() || !FilterIds.empty();
 
   // Type infos.
   MCSection *LSDASection = Asm->getObjFileLowering().getLSDASection();
   unsigned TTypeEncoding;
 
MCSymbol *EHStreamer::emitExceptionTable() {
 
   // Emit the landing pad call site table.
   MCSymbol *CstBeginLabel = Asm->createTempSymbol("cst_begin");
   MCSymbol *CstEndLabel = Asm->createTempSymbol("cst_end");
   Asm->EmitEncodingByte(CallSiteEncoding, "Call site");
   Asm->EmitLabelDifferenceAsULEB128(CstEndLabel, CstBeginLabel);
   Asm->OutStreamer->EmitLabel(CstBeginLabel);
 
-  // SjLj Exception handling
-  if (IsSJLJ) {
+  // SjLj / Wasm Exception handling
+  if (IsSJLJ || IsWasm) {
     unsigned idx = 0;
     for (SmallVectorImpl<CallSiteEntry>::const_iterator
          I = CallSites.begin(), E = CallSites.end(); I != E; ++I, ++idx) {
       const CallSiteEntry &S = *I;
 
       // Index of the call site entry.
       if (VerboseAsm) {
         Asm->OutStreamer->AddComment(">> Call Site " + Twine(idx) + " <<");
for (SmallVectorImpl<ActionEntry>::const_iterator
     Asm->EmitSLEB128(Action.NextAction);
   }
 
   if (HaveTTData) {
     Asm->EmitAlignment(2);
     emitTypeInfos(TTypeEncoding, TTBaseLabel);
   }
 
+  // In wasm, we need to emit .size before the alignment, so we bail out here.
+  if (IsWasm)
+    return GCCETSym;
+
   Asm->EmitAlignment(2);
+  return GCCETSym;
 }
 
 void EHStreamer::emitTypeInfos(unsigned TTypeEncoding, MCSymbol *TTBaseLabel) {
   const MachineFunction *MF = Asm->MF;
   const std::vector<const GlobalValue *> &TypeInfos = MF->getTypeInfos();
   const std::vector<unsigned> &FilterIds = MF->getFilterIds();
 
   bool VerboseAsm = Asm->OutStreamer->isVerboseAsm();

lib/CodeGen/AsmPrinter/WasmException.h

+//===-- WasmException.h - Wasm Exception Framework -------------*- C++ -*--===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for writing WebAssembly exception info into asm
+// files.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIB_CODEGEN_ASMPRINTER_WASMEXCEPTION_H
+#define LLVM_LIB_CODEGEN_ASMPRINTER_WASMEXCEPTION_H
+
+#include "EHStreamer.h"
+#include "llvm/CodeGen/AsmPrinter.h"
+
+namespace llvm {
+
+class LLVM_LIBRARY_VISIBILITY WasmException : public EHStreamer {
+public:
+  WasmException(AsmPrinter *A) : EHStreamer(A) {}
+
+  void endModule() override {}
+  void beginFunction(const MachineFunction *MF) override {}
+  virtual void markFunctionEnd() override;
+  void endFunction(const MachineFunction *MF) override;
+
+protected:
+  // Compute the call site table for wasm EH.
+  void computeCallSiteTable(
+      SmallVectorImpl<CallSiteEntry> &CallSites,
+      const SmallVectorImpl<const LandingPadInfo *> &LandingPads,
+      const SmallVectorImpl<unsigned> &FirstActions) override;
+};
+
+} // End of namespace llvm
+
+#endif

lib/CodeGen/AsmPrinter/WasmException.cpp

+//===-- CodeGen/AsmPrinter/WasmException.cpp - Wasm Exception Impl --------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains support for writing WebAssembly exception info into asm
+// files.
+//
+//===----------------------------------------------------------------------===//
+
+#include "WasmException.h"
+#include "llvm/MC/MCStreamer.h"
+using namespace llvm;
+
+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 auto &Info : MF->getLandingPads()) {
+    if (MF->hasWasmLandingPadIndex(Info.LandingPadBlock)) {
+      ShouldEmitExceptionTable = true;
+      break;
+    }
+  }
+  if (!ShouldEmitExceptionTable)
+    return;
+  MCSymbol *LSDALabel = emitExceptionTable();
+  assert(LSDALabel && ".GCC_exception_table has not been emitted!");
+
+  // Wasm requires every data section symbol to have a .size set. So we emit an
+  // end marker and set the size as the difference between the start end the end
+  // marker.
+  MCSymbol *LSDAEndLabel = Asm->createTempSymbol("GCC_except_table_end");
+  Asm->OutStreamer->EmitLabel(LSDAEndLabel);
+  MCContext &OutContext = Asm->OutStreamer->getContext();
+  const MCExpr *SizeExp = MCBinaryExpr::createSub(
+      MCSymbolRefExpr::create(LSDAEndLabel, OutContext),
+      MCSymbolRefExpr::create(LSDALabel, OutContext), OutContext);
+  Asm->OutStreamer->emitELFSize(LSDALabel, SizeExp);
+  Asm->EmitAlignment(2);
+}
+
+// Compute the call-site table for wasm EH. Even though we use the same function
+// name to share the common routines, a call site entry in the table corresponds
+// to not a call site for possibly-throwing functions but a landing pad. In wasm
+// EH the VM is responsible for stack unwinding. After an exception occurs and
+// the stack is unwound, the control flow is transferred to wasm 'catch'
+// instruction by the VM, after which the personality function is called from
+// the compiler-generated code. Refer to WasmEHPrepare pass for more
+// information.
+void WasmException::computeCallSiteTable(
+    SmallVectorImpl<CallSiteEntry> &CallSites,
+    const SmallVectorImpl<const LandingPadInfo *> &LandingPads,
+    const SmallVectorImpl<unsigned> &FirstActions) {
+  MachineFunction &MF = *Asm->MF;
+  for (unsigned I = 0, N = LandingPads.size(); I < N; ++I) {
+    const LandingPadInfo *Info = LandingPads[I];
+    MachineBasicBlock *LPad = Info->LandingPadBlock;
+    // We don't emit LSDA for single catch (...).
+    if (!MF.hasWasmLandingPadIndex(LPad))
+      continue;
+    // Wasm EH must maintain the EH pads in the order assigned to them by the
+    // WasmEHPrepare pass.
+    unsigned LPadIndex = MF.getWasmLandingPadIndex(LPad);
+    CallSiteEntry Site = {nullptr, nullptr, Info, FirstActions[I]};
+    if (CallSites.size() < LPadIndex + 1)
+      CallSites.resize(LPadIndex + 1);
+    CallSites[LPadIndex] = Site;
+  }
+}

lib/CodeGen/MachineFunction.cpp

for (unsigned I = LPI->getNumClauses(); I != 0; --I) {
         for (User::op_iterator II = CVal->op_begin(), IE = CVal->op_end();
              II != IE; ++II)
           FilterList.push_back(cast<GlobalValue>((*II)->stripPointerCasts()));
 
         addFilterTypeInfo(LandingPad, FilterList);
       }
     }
 
-  } else if (isa<CatchPadInst>(FirstI)) {
-    // TODO
+  } else if (const auto *CPI = dyn_cast<CatchPadInst>(FirstI)) {
+    for (unsigned I = CPI->getNumArgOperands(); I != 0; --I) {
+      Value *TypeInfo = CPI->getArgOperand(I - 1)->stripPointerCasts();
+      addCatchTypeInfo(LandingPad, dyn_cast<GlobalValue>(TypeInfo));
+    }
 
   } else {
     assert(isa<CleanupPadInst>(FirstI) && "Invalid landingpad!");
   }
 
   return LandingPadLabel;
 }
 
 void MachineFunction::addCatchTypeInfo(MachineBasicBlock *LandingPad,
                                        ArrayRef<const GlobalValue *> TyInfo) {
   LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
   for (unsigned N = TyInfo.size(); N; --N)
     LP.TypeIds.push_back(getTypeIDFor(TyInfo[N - 1]));
 }
 
 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) {
+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;
+        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;
   }

lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp

SDValue N(DAG.getMachineNode(TargetOpcode::ICALL_BRANCH_FUNNEL,
                                  getCurSDLoc(), MVT::Other, Ops),
               0);
     DAG.setRoot(N);
     setValue(&I, N);
     HasTailCall = true;
     return nullptr;
   }
 
-  case Intrinsic::wasm_landingpad_index: {
-    // TODO store landing pad index in a map, which will be used when generating
-    // LSDA information
+  case Intrinsic::wasm_landingpad_index:
+    // Information this intrinsic contained has been transferred to
+    // MachineFunction in SelectionDAGISel::PrepareEHLandingPad. We can safely
+    // delete it now.
     return nullptr;
   }
-  }
-}
 
 void SelectionDAGBuilder::visitConstrainedFPIntrinsic(
     const ConstrainedFPIntrinsic &FPI) {
   SDLoc sdl = getCurSDLoc();
   unsigned Opcode;
   switch (FPI.getIntrinsicID()) {
   default: llvm_unreachable("Impossible intrinsic");  // Can't reach here.
   case Intrinsic::experimental_constrained_fadd:
if (EHPadBB) {
     auto Pers = classifyEHPersonality(FuncInfo.Fn->getPersonalityFn());
     // There is a platform (e.g. wasm) that uses funclet style IR but does not
     // actually use outlined funclets and their LSDA info style.
     if (MF.hasEHFunclets() && isFuncletEHPersonality(Pers)) {
       assert(CLI.CS);
       WinEHFuncInfo *EHInfo = DAG.getMachineFunction().getWinEHFuncInfo();
       EHInfo->addIPToStateRange(cast<InvokeInst>(CLI.CS.getInstruction()),
                                 BeginLabel, EndLabel);
-    } else {
+    } else if (!isScopedEHPersonality(Pers)) {
       MF.addInvoke(FuncInfo.MBBMap[EHPadBB], BeginLabel, EndLabel);
     }
   }
 
   return Result;
 }
 
 void SelectionDAGBuilder::LowerCallTo(ImmutableCallSite CS, SDValue Callee,

lib/CodeGen/SelectionDAG/SelectionDAGISel.cpp

 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
 #include "llvm/ADT/StringRef.h"
 #include "llvm/Analysis/AliasAnalysis.h"
 #include "llvm/Analysis/BranchProbabilityInfo.h"
 #include "llvm/Analysis/CFG.h"
+#include "llvm/Analysis/EHPersonalities.h"
 #include "llvm/Analysis/OptimizationRemarkEmitter.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/TargetTransformInfo.h"
 #include "llvm/CodeGen/FastISel.h"
 #include "llvm/CodeGen/FunctionLoweringInfo.h"
 #include "llvm/CodeGen/GCMetadata.h"
 #include "llvm/CodeGen/ISDOpcodes.h"
 #include "llvm/CodeGen/MachineBasicBlock.h"

 /// do other setup for EH landing-pad blocks.
 bool SelectionDAGISel::PrepareEHLandingPad() {
   MachineBasicBlock *MBB = FuncInfo->MBB;
   const Constant *PersonalityFn = FuncInfo->Fn->getPersonalityFn();
   const BasicBlock *LLVMBB = MBB->getBasicBlock();
   const TargetRegisterClass *PtrRC =
       TLI->getRegClassFor(TLI->getPointerTy(CurDAG->getDataLayout()));
 
+  auto Pers = classifyEHPersonality(PersonalityFn);
+
   // Catchpads have one live-in register, which typically holds the exception
   // pointer or code.
+  if (isFuncletEHPersonality(Pers)) {
     if (const auto *CPI = dyn_cast<CatchPadInst>(LLVMBB->getFirstNonPHI())) {
       if (hasExceptionPointerOrCodeUser(CPI)) {
         // Get or create the virtual register to hold the pointer or code.  Mark
         // the live in physreg and copy into the vreg.
         MCPhysReg EHPhysReg = TLI->getExceptionPointerRegister(PersonalityFn);
         assert(EHPhysReg && "target lacks exception pointer register");
         MBB->addLiveIn(EHPhysReg);
         unsigned VReg = FuncInfo->getCatchPadExceptionPointerVReg(CPI, PtrRC);
         BuildMI(*MBB, FuncInfo->InsertPt, SDB->getCurDebugLoc(),
                 TII->get(TargetOpcode::COPY), VReg)
             .addReg(EHPhysReg, RegState::Kill);
       }
-    return true;
     }
-
-  if (!LLVMBB->isLandingPad())
     return true;
+  }
 
   // Add a label to mark the beginning of the landing pad.  Deletion of the
   // landing pad can thus be detected via the MachineModuleInfo.
   MCSymbol *Label = MF->addLandingPad(MBB);
 
-  // Assign the call site to the landing pad's begin label.
-  MF->setCallSiteLandingPad(Label, SDB->LPadToCallSiteMap[MBB]);
-
   const MCInstrDesc &II = TII->get(TargetOpcode::EH_LABEL);
   BuildMI(*MBB, FuncInfo->InsertPt, SDB->getCurDebugLoc(), II)
     .addSym(Label);
 
+  if (Pers == EHPersonality::Wasm_CXX) {
+    if (const auto *CPI = dyn_cast<CatchPadInst>(LLVMBB->getFirstNonPHI())) {
+      // In case of single catch (...), we don't emit LSDA, so we don't need
+      // this information.
+      bool IsSingleCatchAllClause =
+          CPI->getNumArgOperands() == 1 &&
+          cast<Constant>(CPI->getArgOperand(0))->isNullValue();
+      if (!IsSingleCatchAllClause) {
+        // Create a mapping from landing pad label to landing pad index.
+        bool IntrFound = false;
+        for (const User *U : CPI->users()) {
+          if (const auto *Call = dyn_cast<IntrinsicInst>(U)) {
+            Intrinsic::ID IID = Call->getIntrinsicID();
+            if (IID == Intrinsic::wasm_landingpad_index) {
+              Value *IndexArg = Call->getArgOperand(1);
+              int Index = cast<ConstantInt>(IndexArg)->getZExtValue();
+              MF->setWasmLandingPadIndex(MBB, Index);
+              IntrFound = true;
+              break;
+            }
+          }
+        }
+        assert(IntrFound && "wasm.landingpad.index intrinsic not found!");
+      }
+    }
+
+  } else {
+    // Assign the call site to the landing pad's begin label.
+    MF->setCallSiteLandingPad(Label, SDB->LPadToCallSiteMap[MBB]);
     // Mark exception register as live in.
     if (unsigned Reg = TLI->getExceptionPointerRegister(PersonalityFn))
       FuncInfo->ExceptionPointerVirtReg = MBB->addLiveIn(Reg, PtrRC);
-
     // Mark exception selector register as live in.
     if (unsigned Reg = TLI->getExceptionSelectorRegister(PersonalityFn))
       FuncInfo->ExceptionSelectorVirtReg = MBB->addLiveIn(Reg, PtrRC);
+  }
 
   return true;
 }
 
 /// isFoldedOrDeadInstruction - Return true if the specified instruction is
 /// side-effect free and is either dead or folded into a generated instruction.
 /// Return false if it needs to be emitted.
 static bool isFoldedOrDeadInstruction(const Instruction *I,

lib/CodeGen/TargetLoweringObjectFileImpl.cpp

return MCBinaryExpr::createSub(
       MCSymbolRefExpr::create(TM.getSymbol(LHS), MCSymbolRefExpr::VK_None,
                               getContext()),
       MCSymbolRefExpr::create(TM.getSymbol(RHS), getContext()), getContext());
 }
 
 void TargetLoweringObjectFileWasm::InitializeWasm() {
   StaticCtorSection =
       getContext().getWasmSection(".init_array", SectionKind::getData());
+
+  // We don't use PersonalityEncoding and LSDAEncoding because we don't emit
+  // .cfi directives. We use TTypeEncoding to encode typeinfo global variables.
+  TTypeEncoding = dwarf::DW_EH_PE_absptr;
 }
 
 MCSection *TargetLoweringObjectFileWasm::getStaticCtorSection(
     unsigned Priority, const MCSymbol *KeySym) const {
   return Priority == UINT16_MAX ?
          StaticCtorSection :
          getContext().getWasmSection(".init_array." + utostr(Priority),
                                      SectionKind::getData());
 }
 
 MCSection *TargetLoweringObjectFileWasm::getStaticDtorSection(
     unsigned Priority, const MCSymbol *KeySym) const {
   llvm_unreachable("@llvm.global_dtors should have been lowered already");
   return nullptr;
 }

lib/CodeGen/WasmEHPrepare.cpp

if (FPI->getNumArgOperands() == 0 ||
     }
     return;
   }
   IRB.SetInsertPoint(Exn->getNextNode());
 
   // This is to create a map of <landingpad EH label, landingpad index> in
   // SelectionDAGISel, which is to be used in EHStreamer to emit LSDA tables.
   // Pseudocode: wasm.landingpad.index(Index);
-  IRB.CreateCall(LPadIndexF, IRB.getInt32(Index));
+  IRB.CreateCall(LPadIndexF, {FPI, IRB.getInt32(Index)});
 
   // Pseudocode: __wasm_lpad_context.lpad_index = index;
   IRB.CreateStore(IRB.getInt32(Index), LPadIndexField);
 
   // Store LSDA address only if this catchpad belongs to a top-level
   // catchswitch. If there is another catchpad that dominates this pad, we don't
   // need to store LSDA address again, because they are the same throughout the
   // function and have been already stored before.

lib/MC/MCObjectFileInfo.cpp

void MCObjectFileInfo::initWasmMCObjectFileInfo(const Triple &T) {
   DwarfCUIndexSection = Ctx->getWasmSection(".debug_cu_index", SectionKind::getMetadata());
   DwarfTUIndexSection = Ctx->getWasmSection(".debug_tu_index", SectionKind::getMetadata());
   DwarfInfoSection =
       Ctx->getWasmSection(".debug_info", SectionKind::getMetadata());
   DwarfFrameSection = Ctx->getWasmSection(".debug_frame", SectionKind::getMetadata());
   DwarfPubNamesSection = Ctx->getWasmSection(".debug_pubnames", SectionKind::getMetadata());
   DwarfPubTypesSection = Ctx->getWasmSection(".debug_pubtypes", SectionKind::getMetadata());
 
+  // Wasm use data section for LSDA.
+  // TODO Consider putting each function's exception table in a separate
+  // section, as in -function-sections, to facilitate lld's --gc-section.
+  LSDASection = Ctx->getWasmSection(".rodata.gcc_except_table",
+                                    SectionKind::getReadOnlyWithRel());
+
   // TODO: Define more sections.
 }
 
 void MCObjectFileInfo::InitMCObjectFileInfo(const Triple &TheTriple, bool PIC,
                                             MCContext &ctx,
                                             bool LargeCodeModel) {
   PositionIndependent = PIC;
   Ctx = &ctx;

lib/MC/WasmObjectWriter.cpp

if (auto *Align = dyn_cast<MCAlignFragment>(&Frag)) {
                              DataBytes.size() + Align->getMaxBytesToEmit());
       DataBytes.resize(Size, Value);
     } else if (auto *Fill = dyn_cast<MCFillFragment>(&Frag)) {
       int64_t NumValues;
       if (!Fill->getNumValues().evaluateAsAbsolute(NumValues))
         llvm_unreachable("The fill should be an assembler constant");
       DataBytes.insert(DataBytes.end(), Fill->getValueSize() * NumValues,
                        Fill->getValue());
+    } else if (auto *LEB = dyn_cast<MCLEBFragment>(&Frag)) {
+      const SmallVectorImpl<char> &Contents = LEB->getContents();
+      DataBytes.insert(DataBytes.end(), Contents.begin(), Contents.end());
     } else {
       const auto &DataFrag = cast<MCDataFragment>(Frag);
       const SmallVectorImpl<char> &Contents = DataFrag.getContents();
-
       DataBytes.insert(DataBytes.end(), Contents.begin(), Contents.end());
     }
   }
 
   LLVM_DEBUG(dbgs() << "addData -> " << DataBytes.size() << "\n");
 }
 
 uint32_t

lib/Target/WebAssembly/WebAssemblyISelLowering.cpp

 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
 #include "WebAssemblyMachineFunctionInfo.h"
 #include "WebAssemblySubtarget.h"
 #include "WebAssemblyTargetMachine.h"
 #include "llvm/CodeGen/Analysis.h"
 #include "llvm/CodeGen/CallingConvLower.h"
 #include "llvm/CodeGen/MachineInstrBuilder.h"
 #include "llvm/CodeGen/MachineJumpTableInfo.h"
+#include "llvm/CodeGen/MachineModuleInfo.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/SelectionDAG.h"
 #include "llvm/IR/DiagnosticInfo.h"
 #include "llvm/IR/DiagnosticPrinter.h"
 #include "llvm/IR/Function.h"
 #include "llvm/IR/Intrinsics.h"
 #include "llvm/Support/Debug.h"
 #include "llvm/Support/ErrorHandling.h"
WebAssemblyTargetLowering::LowerINTRINSIC_WO_CHAIN(SDValue Op,
                                                    SelectionDAG &DAG) const {
   unsigned IntNo = cast<ConstantSDNode>(Op.getOperand(0))->getZExtValue();
   SDLoc DL(Op);
   switch (IntNo) {
   default:
     return {}; // Don't custom lower most intrinsics.
 
   case Intrinsic::wasm_lsda:
-    // TODO For now, just return 0 not to crash
-    return DAG.getConstant(0, DL, Op.getValueType());
+    MachineFunction &MF = DAG.getMachineFunction();
+    EVT VT = Op.getValueType();
+    const TargetLowering &TLI = DAG.getTargetLoweringInfo();
+    MVT PtrVT = TLI.getPointerTy(DAG.getDataLayout());
+    auto &Context = MF.getMMI().getContext();
+    MCSymbol *S = Context.getOrCreateSymbol(Twine("GCC_except_table") +
+                                            Twine(MF.getFunctionNumber()));
+    return DAG.getNode(WebAssemblyISD::Wrapper, DL, VT,
+                       DAG.getMCSymbol(S, PtrVT));
   }
 }
 
 SDValue
 WebAssemblyTargetLowering::LowerVECTOR_SHUFFLE(SDValue Op,
                                                SelectionDAG &DAG) const {
   SDLoc DL(Op);
   ArrayRef<int> Mask = cast<ShuffleVectorSDNode>(Op.getNode())->getMask();

lib/Target/WebAssembly/WebAssemblyInstrInfo.td

 } // isMoveImm = 1, isAsCheapAsAMove = 1, isReMaterializable = 1
 
 } // Defs = [ARGUMENTS]
 
 def : Pat<(i32 (WebAssemblywrapper tglobaladdr:$addr)),
           (CONST_I32 tglobaladdr:$addr)>;
 def : Pat<(i32 (WebAssemblywrapper texternalsym:$addr)),
           (CONST_I32 texternalsym:$addr)>;
+def : Pat<(i32 (WebAssemblywrapper mcsym:$sym)), (CONST_I32 mcsym:$sym)>;
+def : Pat<(i64 (WebAssemblywrapper mcsym:$sym)), (CONST_I64 mcsym:$sym)>;
 
 //===----------------------------------------------------------------------===//
 // Additional sets of instructions.
 //===----------------------------------------------------------------------===//
 
 include "WebAssemblyInstrMemory.td"
 include "WebAssemblyInstrCall.td"
 include "WebAssemblyInstrControl.td"
 include "WebAssemblyInstrInteger.td"
 include "WebAssemblyInstrConv.td"
 include "WebAssemblyInstrFloat.td"
 include "WebAssemblyInstrAtomics.td"
 include "WebAssemblyInstrSIMD.td"
 include "WebAssemblyInstrExceptRef.td"

lib/Target/WebAssembly/WebAssemblyMCInstLower.cpp

case MachineOperand::MO_ExternalSymbol:
       // variable or a function.
       assert((MO.getTargetFlags() & ~WebAssemblyII::MO_SYMBOL_MASK) == 0 &&
              "WebAssembly uses only symbol flags on ExternalSymbols");
       MCOp = LowerSymbolOperand(
           GetExternalSymbolSymbol(MO), /*Offset=*/0,
           (MO.getTargetFlags() & WebAssemblyII::MO_SYMBOL_FUNCTION) != 0,
           (MO.getTargetFlags() & WebAssemblyII::MO_SYMBOL_GLOBAL) != 0);
       break;
+    case MachineOperand::MO_MCSymbol:
+      // This is currently used only for LSDA symbols (GCC_except_table),
+      // because global addresses or other external symbols are handled above.
+      assert(MO.getTargetFlags() == 0 &&
+             "WebAssembly does not use target flags on MCSymbol");
+      MCOp = LowerSymbolOperand(MO.getMCSymbol(), /*Offset=*/0, false, false);
+      break;
     }
 
     OutMI.addOperand(MCOp);
   }
 
   if (!WasmKeepRegisters)
     removeRegisterOperands(MI, OutMI);
 }

test/CodeGen/WebAssembly/eh-lsda.ll

+; RUN: llc < %s -disable-wasm-fallthrough-return-opt -wasm-keep-registers -exception-model=wasm -mattr=+exception-handling | FileCheck -allow-deprecated-dag-overlap %s
+target datalayout = "e-m:e-p:32:32-i64:64-n32:64-S128"
+target triple = "wasm32-unknown-unknown"
+
+@_ZTIi = external constant i8*
+@_ZTIf = external constant i8*
+@_ZTId = external constant i8*
+
+; Single catch (...) does not need an exception table.
+; CHECK-LABEL: test0:
+; CHECK-NOT: GCC_except_table
+define void @test0() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {
+entry:
+  invoke void @may_throw()
+          to label %try.cont unwind label %catch.dispatch
+
+catch.dispatch:                                   ; preds = %entry
+  %0 = catchswitch within none [label %catch.start] unwind to caller
+
+catch.start:                                      ; preds = %catch.dispatch
+  %1 = catchpad within %0 [i8* null]
+  %2 = call i8* @llvm.wasm.get.exception(token %1)
+  %3 = call i32 @llvm.wasm.get.ehselector(token %1)
+  %4 = call i8* @__cxa_begin_catch(i8* %2) [ "funclet"(token %1) ]
+  call void @__cxa_end_catch() [ "funclet"(token %1) ]
+  catchret from %1 to label %try.cont
+
+try.cont:                                         ; preds = %entry, %catch.start
+  ret void
+}
+
+; Exception table generation + shared action test.
+; There are three landing pads. The second landing pad should share action table
+; entries with the first landing pad because they end with the same sequence
+; (double -> ...). But the third landing table cannot share action table entries
+; with others, so it should create its own entries.
+; CHECK-LABEL: test1:
+; CHECK: .section  .rodata.gcc_except_table,"",@
+; CHECK-NEXT:   .p2align  2
+; CHECK-NEXT: GCC_except_table[[START:[0-9]+]]:
+; CHECK-NEXT: .Lexception0:
+; CHECK-NEXT:   .int8  255                     # @LPStart Encoding = omit
+; CHECK-NEXT:   .int8  0                       # @TType Encoding = absptr
+; CHECK-NEXT:   .uleb128 .Lttbase0-.Lttbaseref0
+; CHECK-NEXT: .Lttbaseref0:
+; CHECK-NEXT:   .int8  1                       # Call site Encoding = uleb128
+; CHECK-NEXT:   .uleb128 .Lcst_end0-.Lcst_begin0
+; CHECK-NEXT: .Lcst_begin0:
+; CHECK-NEXT:   .int8  0                       # >> Call Site 0 <<
+; CHECK-NEXT:                                  #   On exception at call site 0
+; CHECK-NEXT:   .int8  7                       #   Action: 4
+; CHECK-NEXT:   .int8  1                       # >> Call Site 1 <<
+; CHECK-NEXT:                                  #   On exception at call site 1
+; CHECK-NEXT:   .int8  3                       #   Action: 2
+; CHECK-NEXT:   .int8  2                       # >> Call Site 2 <<
+; CHECK-NEXT:                                  #   On exception at call site 2
+; CHECK-NEXT:   .int8  11                      #   Action: 6
+; CHECK-NEXT: .Lcst_end0:
+; CHECK-NEXT:   .int8  1                       # >> Action Record 1 <<
+; CHECK-NEXT:                                  #   Catch TypeInfo 1
+; CHECK-NEXT:   .int8  0                       #   No further actions
+; CHECK-NEXT:   .int8  2                       # >> Action Record 2 <<
+; CHECK-NEXT:                                  #   Catch TypeInfo 2
+; CHECK-NEXT:   .int8  125                     #   Continue to action 1
+; CHECK-NEXT:   .int8  3                       # >> Action Record 3 <<
+; CHECK-NEXT:                                  #   Catch TypeInfo 3
+; CHECK-NEXT:   .int8  125                     #   Continue to action 2
+; CHECK-NEXT:   .int8  4                       # >> Action Record 4 <<
+; CHECK-NEXT:                                  #   Catch TypeInfo 4
+; CHECK-NEXT:   .int8  125                     #   Continue to action 3
+; CHECK-NEXT:   .int8  3                       # >> Action Record 5 <<
+; CHECK-NEXT:                                  #   Catch TypeInfo 3
+; CHECK-NEXT:   .int8  0                       #   No further actions
+; CHECK-NEXT:   .int8  4                       # >> Action Record 6 <<
+; CHECK-NEXT:                                  #   Catch TypeInfo 4
+; CHECK-NEXT:   .int8  125                     #   Continue to action 5
+; CHECK-NEXT:   .p2align  2
+; CHECK-NEXT:                                  # >> Catch TypeInfos <<
+; CHECK-NEXT:   .int32  _ZTIi                  # TypeInfo 4
+; CHECK-NEXT:   .int32  _ZTIf                  # TypeInfo 3
+; CHECK-NEXT:   .int32  _ZTId                  # TypeInfo 2
+; CHECK-NEXT:   .int32  0                      # TypeInfo 1
+; CHECK-NEXT: .Lttbase0:
+; CHECK-NEXT: .LGCC_except_table_end[[END:[0-9]+]]:
+; CHECK-NEXT:   .size  GCC_except_table[[START]], .LGCC_except_table_end[[END]]-GCC_except_table[[START]]
+; CHECK-NEXT:   .p2align  2
+define void @test1() personality i8* bitcast (i32 (...)* @__gxx_wasm_personality_v0 to i8*) {
+entry:
+  invoke void @may_throw()
+          to label %try.cont unwind label %catch.dispatch
+
+catch.dispatch:                                   ; preds = %entry
+  %0 = catchswitch within none [label %catch.start] unwind to caller
+
+catch.start:                                      ; preds = %catch.dispatch
+  %1 = catchpad within %0 [i8* bitcast (i8** @_ZTIi to i8*), i8* bitcast (i8** @_ZTIf to i8*), i8* bitcast (i8** @_ZTId to i8*), i8* null]
+  %2 = call i8* @llvm.wasm.get.exception(token %1)
+  %3 = call i32 @llvm.wasm.get.ehselector(token %1)
+  %4 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*))
+  %matches = icmp eq i32 %3, %4
+  br i1 %matches, label %catch10, label %catch.fallthrough
+
+catch10:                                          ; preds = %catch.start
+  %5 = call i8* @__cxa_begin_catch(i8* %2) [ "funclet"(token %1) ]
+  %6 = bitcast i8* %5 to i32*
+  %7 = load i32, i32* %6, align 4
+  call void @__cxa_end_catch() [ "funclet"(token %1) ]
+  catchret from %1 to label %try.cont
+
+try.cont:                                         ; preds = %entry, %catch, %catch4, %catch7, %catch10
+  invoke void @may_throw()
+          to label %try.cont23 unwind label %catch.dispatch14
+
+catch.dispatch14:                                 ; preds = %try.cont
+  %8 = catchswitch within none [label %catch.start15] unwind to caller
+
+catch.start15:                                    ; preds = %catch.dispatch14
+  %9 = catchpad within %8 [i8* bitcast (i8** @_ZTId to i8*), i8* null]
+  %10 = call i8* @llvm.wasm.get.exception(token %9)
+  %11 = call i32 @llvm.wasm.get.ehselector(token %9)
+  %12 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTId to i8*))
+  %matches16 = icmp eq i32 %11, %12
+  %13 = call i8* @__cxa_begin_catch(i8* %10) [ "funclet"(token %9) ]
+  br i1 %matches16, label %catch20, label %catch17
+
+catch20:                                          ; preds = %catch.start15
+  %14 = bitcast i8* %13 to double*
+  %15 = load double, double* %14, align 8
+  call void @__cxa_end_catch() [ "funclet"(token %9) ]
+  catchret from %9 to label %try.cont23
+
+try.cont23:                                       ; preds = %try.cont, %catch17, %catch20
+  invoke void @may_throw()
+          to label %try.cont36 unwind label %catch.dispatch25
+
+catch.dispatch25:                                 ; preds = %try.cont23
+  %16 = catchswitch within none [label %catch.start26] unwind to caller
+
+catch.start26:                                    ; preds = %catch.dispatch25
+  %17 = catchpad within %16 [i8* bitcast (i8** @_ZTIi to i8*), i8* bitcast (i8** @_ZTIf to i8*)]
+  %18 = call i8* @llvm.wasm.get.exception(token %17)
+  %19 = call i32 @llvm.wasm.get.ehselector(token %17)
+  %20 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*))
+  %matches27 = icmp eq i32 %19, %20
+  br i1 %matches27, label %catch33, label %catch.fallthrough28
+
+catch33:                                          ; preds = %catch.start26
+  %21 = call i8* @__cxa_begin_catch(i8* %18) [ "funclet"(token %17) ]
+  %22 = bitcast i8* %21 to i32*
+  %23 = load i32, i32* %22, align 4
+  call void @__cxa_end_catch() [ "funclet"(token %17) ]
+  catchret from %17 to label %try.cont36
+
+catch.fallthrough28:                              ; preds = %catch.start26
+  %24 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIf to i8*))
+  %matches29 = icmp eq i32 %19, %24
+  br i1 %matches29, label %catch30, label %rethrow
+
+catch30:                                          ; preds = %catch.fallthrough28
+  %25 = call i8* @__cxa_begin_catch(i8* %18) [ "funclet"(token %17) ]
+  %26 = bitcast i8* %25 to float*
+  %27 = load float, float* %26, align 4
+  call void @__cxa_end_catch() [ "funclet"(token %17) ]
+  catchret from %17 to label %try.cont36
+
+rethrow:                                          ; preds = %catch.fallthrough28
+  call void @__cxa_rethrow() [ "funclet"(token %17) ]
+  unreachable
+
+try.cont36:                                       ; preds = %try.cont23, %catch30, %catch33
+  ret void
+
+catch17:                                          ; preds = %catch.start15
+  call void @__cxa_end_catch() [ "funclet"(token %9) ]
+  catchret from %9 to label %try.cont23
+
+catch.fallthrough:                                ; preds = %catch.start
+  %28 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIf to i8*))
+  %matches1 = icmp eq i32 %3, %28
+  br i1 %matches1, label %catch7, label %catch.fallthrough2
+
+catch7:                                           ; preds = %catch.fallthrough
+  %29 = call i8* @__cxa_begin_catch(i8* %2) [ "funclet"(token %1) ]
+  %30 = bitcast i8* %29 to float*
+  %31 = load float, float* %30, align 4
+  call void @__cxa_end_catch() [ "funclet"(token %1) ]
+  catchret from %1 to label %try.cont
+
+catch.fallthrough2:                               ; preds = %catch.fallthrough
+  %32 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTId to i8*))
+  %matches3 = icmp eq i32 %3, %32
+  %33 = call i8* @__cxa_begin_catch(i8* %2) [ "funclet"(token %1) ]
+  br i1 %matches3, label %catch4, label %catch
+
+catch4:                                           ; preds = %catch.fallthrough2
+  %34 = bitcast i8* %33 to double*
+  %35 = load double, double* %34, align 8
+  call void @__cxa_end_catch() [ "funclet"(token %1) ]
+  catchret from %1 to label %try.cont
+
+catch:                                            ; preds = %catch.fallthrough2
+  call void @__cxa_end_catch() [ "funclet"(token %1) ]
+  catchret from %1 to label %try.cont
+}
+
+declare void @may_throw()
+declare i32 @llvm.eh.typeid.for(i8*)
+declare i8* @llvm.wasm.get.exception(token)
+declare i32 @llvm.wasm.get.ehselector(token)
+declare void @__cxa_rethrow()
+declare i8* @__cxa_begin_catch(i8*)
+declare void @__cxa_end_catch()
+declare i32 @__gxx_wasm_personality_v0(...)

test/CodeGen/WebAssembly/wasmehprepare.ll

catch.start:                                      ; preds = %catch.dispatch
   %2 = call i8* @llvm.wasm.get.exception(token %1)
   %3 = call i32 @llvm.wasm.get.ehselector(token %1)
   %4 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*))
   %matches = icmp eq i32 %3, %4
   br i1 %matches, label %catch, label %rethrow
 ; CHECK: catch.start:
 ; CHECK-NEXT:   %[[CATCHPAD:.*]] = catchpad
 ; CHECK-NEXT:   %[[EXN:.*]] = call i8* @llvm.wasm.catch(i32 0)
-; CHECK-NEXT:   call void @llvm.wasm.landingpad.index(i32 0)
+; CHECK-NEXT:   call void @llvm.wasm.landingpad.index(token %[[CATCHPAD]], i32 0)
 ; CHECK-NEXT:   store i32 0, i32* getelementptr inbounds ({ i32, i8*, i32 }, { i32, i8*, i32 }* @__wasm_lpad_context, i32 0, i32 0)
 ; CHECK-NEXT:   %[[LSDA:.*]] = call i8* @llvm.wasm.lsda()
 ; CHECK-NEXT:   store i8* %[[LSDA]], i8** getelementptr inbounds ({ i32, i8*, i32 }, { i32, i8*, i32 }* @__wasm_lpad_context, i32 0, i32 1)
 ; CHECK-NEXT:   call i32 @_Unwind_CallPersonality(i8* %[[EXN]]) {{.*}} [ "funclet"(token %[[CATCHPAD]]) ]
 ; CHECK-NEXT:   %[[SELECTOR:.*]] = load i32, i32* getelementptr inbounds ({ i32, i8*, i32 }, { i32, i8*, i32 }* @__wasm_lpad_context, i32 0, i32 2)
 ; CHECK:   icmp eq i32 %[[SELECTOR]]
 
 catch:                                            ; preds = %catch.start

 catch.start3:                                     ; preds = %catch.dispatch2
   %6 = catchpad within %5 [i8* bitcast (i8** @_ZTIi to i8*)]
   %7 = call i8* @llvm.wasm.get.exception(token %6)
   %8 = call i32 @llvm.wasm.get.ehselector(token %6)
   %9 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIi to i8*))
   %matches = icmp eq i32 %8, %9
   br i1 %matches, label %catch4, label %rethrow
 ; CHECK: catch.start3:
-; CHECK:   call void @llvm.wasm.landingpad.index(i32 0)
+; CHECK:   call void @llvm.wasm.landingpad.index(token %{{.+}}, i32 0)
 
 catch4:                                           ; preds = %catch.start3
   %10 = call i8* @__cxa_begin_catch(i8* %7) [ "funclet"(token %6) ]
   call void @__cxa_end_catch() [ "funclet"(token %6) ]
   catchret from %6 to label %try.cont7
 
 rethrow:                                          ; preds = %catch.start3
   call void @__cxa_rethrow() [ "funclet"(token %6) ]

 declare i32 @llvm.wasm.get.ehselector(token)
 declare i32 @llvm.eh.typeid.for(i8*)
 declare i8* @__cxa_begin_catch(i8*)
 declare void @__cxa_end_catch()
 declare void @__cxa_rethrow()
 declare void @__clang_call_terminate(i8*)
 
 ; CHECK-DAG: declare i8* @llvm.wasm.catch(i32)
-; CHECK-DAG: declare void @llvm.wasm.landingpad.index(i32)
+; CHECK-DAG: declare void @llvm.wasm.landingpad.index(token, i32)
 ; CHECK-DAG: declare i8* @llvm.wasm.lsda()
 ; CHECK-DAG: declare i32 @_Unwind_CallPersonality(i8*)