8 files changed, 82 insertions, 22 deletions
diff --git a/llvm/include/llvm/Analysis/LibCallSemantics.h b/llvm/include/llvm/Analysis/LibCallSemantics.h
index 170e2a49a8e..b4bef310e59 100644
--- a/llvm/include/llvm/Analysis/LibCallSemantics.h
+++ b/llvm/include/llvm/Analysis/LibCallSemantics.h
@@ -206,6 +206,18 @@ class InvokeInst;
     llvm_unreachable("invalid enum");
   }
 
+  /// \brief Return true if this personality may be safely removed if there
+  /// are no invoke instructions remaining in the current function.
+  inline bool isNoOpWithoutInvoke(EHPersonality Pers) {
+    switch (Pers) {
+    case EHPersonality::Unknown:
+      return false;
+    // All known personalities currently have this behavior
+    default: return true;
+    }
+    llvm_unreachable("invalid enum");
+  }
+
   bool canSimplifyInvokeNoUnwind(const Function *F);
 
 } // end namespace llvm
diff --git a/llvm/include/llvm/CodeGen/MachineModuleInfo.h b/llvm/include/llvm/CodeGen/MachineModuleInfo.h
index ccaa83a238a..4cdfe2463c9 100644
--- a/llvm/include/llvm/CodeGen/MachineModuleInfo.h
+++ b/llvm/include/llvm/CodeGen/MachineModuleInfo.h
@@ -320,6 +320,7 @@ public:
   /// information.
   void addPersonality(MachineBasicBlock *LandingPad,
                       const Function *Personality);
+  void addPersonality(const Function *Personality);
 
   void addWinEHState(MachineBasicBlock *LandingPad, int State);
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/ARMException.cpp b/llvm/lib/CodeGen/AsmPrinter/ARMException.cpp
index 4cb460a7bbf..0bad7954b98 100644
--- a/llvm/lib/CodeGen/AsmPrinter/ARMException.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/ARMException.cpp
@@ -69,24 +69,32 @@ void ARMException::beginFunction(const MachineFunction *MF) {
 ///
 void ARMException::endFunction(const MachineFunction *MF) {
   ARMTargetStreamer &ATS = getTargetStreamer();
+  const Function *F = MF->getFunction();
+  const Function *Per = nullptr;
+  if (F->hasPersonalityFn())
+    Per = dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
+  assert(!MMI->getPersonality() || Per == MMI->getPersonality());
+  bool forceEmitPersonality =
+    F->hasPersonalityFn() && !isNoOpWithoutInvoke(classifyEHPersonality(Per)) &&
+    F->needsUnwindTableEntry();
+  bool shouldEmitPersonality = forceEmitPersonality ||
+    !MMI->getLandingPads().empty();
   if (!Asm->MF->getFunction()->needsUnwindTableEntry() &&
-      MMI->getLandingPads().empty())
+      !shouldEmitPersonality)
     ATS.emitCantUnwind();
-  else {
-    if (!MMI->getLandingPads().empty()) {
-      // Emit references to personality.
-      if (const Function *Personality = MMI->getPersonality()) {
-        MCSymbol *PerSym = Asm->getSymbol(Personality);
-        Asm->OutStreamer->EmitSymbolAttribute(PerSym, MCSA_Global);
-        ATS.emitPersonality(PerSym);
-      }
-
-      // Emit .handlerdata directive.
-      ATS.emitHandlerData();
-
-      // Emit actual exception table
-      emitExceptionTable();
+  else if (shouldEmitPersonality) {
+    // Emit references to personality.
+    if (Per) {
+      MCSymbol *PerSym = Asm->getSymbol(Per);
+      Asm->OutStreamer->EmitSymbolAttribute(PerSym, MCSA_Global);
+      ATS.emitPersonality(PerSym);
     }
+
+    // Emit .handlerdata directive.
+    ATS.emitHandlerData();
+
+    // Emit actual exception table
+    emitExceptionTable();
   }
 
   if (Asm->MAI->getExceptionHandlingType() == ExceptionHandling::ARM)
diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
index 0bc873e326b..2c212c7ecee 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
@@ -89,6 +89,7 @@ void DwarfCFIException::endModule() {
 
 void DwarfCFIException::beginFunction(const MachineFunction *MF) {
   shouldEmitMoves = shouldEmitPersonality = shouldEmitLSDA = false;
+  const Function *F = MF->getFunction();
 
   // If any landing pads survive, we need an EH table.
   bool hasLandingPads = !MMI->getLandingPads().empty();
@@ -104,10 +105,24 @@ void DwarfCFIException::beginFunction(const MachineFunction *MF) {
 
   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
   unsigned PerEncoding = TLOF.getPersonalityEncoding();
-  const Function *Per = MMI->getPersonality();
-
-  shouldEmitPersonality = hasLandingPads &&
-    PerEncoding != dwarf::DW_EH_PE_omit && Per;
+  const Function *Per = nullptr;
+  if (F->hasPersonalityFn())
+    Per = dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
+  assert(!MMI->getPersonality() || Per == MMI->getPersonality());
+
+  // Emit a personality function even when there are no landing pads
+  bool forceEmitPersonality =
+      // ...if a personality function is explicitly specified
+      F->hasPersonalityFn() &&
+      // ... and it's not known to be a noop in the absence of invokes
+      !isNoOpWithoutInvoke(classifyEHPersonality(Per)) &&
+      // ... and we're not explicitly asked not to emit it
+      F->needsUnwindTableEntry();
+
+  shouldEmitPersonality =
+      (forceEmitPersonality ||
+       (hasLandingPads && PerEncoding != dwarf::DW_EH_PE_omit)) &&
+      Per;
 
   unsigned LSDAEncoding = TLOF.getLSDAEncoding();
   shouldEmitLSDA = shouldEmitPersonality &&
@@ -123,6 +138,11 @@ void DwarfCFIException::beginFunction(const MachineFunction *MF) {
   if (!shouldEmitPersonality)
     return;
 
+  // If we are forced to emit this personality, make sure to record
+  // it because it might not appear in any landingpad
+  if (forceEmitPersonality)
+    MMI->addPersonality(Per);
+
   const MCSymbol *Sym =
       TLOF.getCFIPersonalitySymbol(Per, *Asm->Mang, Asm->TM, MMI);
   Asm->OutStreamer->EmitCFIPersonality(Sym, PerEncoding);
diff --git a/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp b/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp
index 1be3fd74d60..49ef8d3ddc8 100644
--- a/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp
@@ -309,7 +309,7 @@ computeCallSiteTable(SmallVectorImpl<CallSiteEntry> &CallSites,
   // If some instruction between the previous try-range and the end of the
   // function may throw, create a call-site entry with no landing pad for the
   // region following the try-range.
-  if (SawPotentiallyThrowing && !IsSJLJ) {
+  if (SawPotentiallyThrowing && !IsSJLJ && LastLabel != nullptr) {
     CallSiteEntry Site = { LastLabel, nullptr, nullptr, 0 };
     CallSites.push_back(Site);
   }
diff --git a/llvm/lib/CodeGen/AsmPrinter/WinException.cpp b/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
index 7ef2832d41a..71c77815e28 100644
--- a/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/WinException.cpp
@@ -74,8 +74,12 @@ void WinException::beginFunction(const MachineFunction *MF) {
   if (F->hasPersonalityFn())
     Per = dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
 
-  shouldEmitPersonality = hasLandingPads &&
-    PerEncoding != dwarf::DW_EH_PE_omit && Per;
+  bool forceEmitPersonality =
+    F->hasPersonalityFn() && !isNoOpWithoutInvoke(classifyEHPersonality(Per)) &&
+    F->needsUnwindTableEntry();
+
+  shouldEmitPersonality = forceEmitPersonality || (hasLandingPads &&
+    PerEncoding != dwarf::DW_EH_PE_omit && Per);
 
   unsigned LSDAEncoding = TLOF.getLSDAEncoding();
   shouldEmitLSDA = shouldEmitPersonality &&
diff --git a/llvm/lib/CodeGen/MachineModuleInfo.cpp b/llvm/lib/CodeGen/MachineModuleInfo.cpp
index 42d0603ab96..6a206249d83 100644
--- a/llvm/lib/CodeGen/MachineModuleInfo.cpp
+++ b/llvm/lib/CodeGen/MachineModuleInfo.cpp
@@ -320,7 +320,10 @@ void MachineModuleInfo::addPersonality(MachineBasicBlock *LandingPad,
                                        const Function *Personality) {
   LandingPadInfo &LP = getOrCreateLandingPadInfo(LandingPad);
   LP.Personality = Personality;
+  addPersonality(Personality);
+}
 
+void MachineModuleInfo::addPersonality(const Function *Personality) {
   for (unsigned i = 0; i < Personalities.size(); ++i)
     if (Personalities[i] == Personality)
       return;
diff --git a/llvm/test/CodeGen/X86/eh-nolandingpads.ll b/llvm/test/CodeGen/X86/eh-nolandingpads.ll
new file mode 100644
index 00000000000..96295226621
--- /dev/null
+++ b/llvm/test/CodeGen/X86/eh-nolandingpads.ll
@@ -0,0 +1,12 @@
+; RUN: llc < %s -mtriple=x86_64-pc-linux | FileCheck %s
+; Test that we emit functions with explicitly specified personality,
+; even if no landing pads are left.
+
+declare i32 @__my_personality_v0(...)
+declare void @might_throw()
+
+define i32 @foo() personality i32 (...)* @__my_personality_v0 {
+; CHECK: .cfi_personality 3, __my_personality_v0
+    call void @might_throw()
+    ret i32 0
+}