[EH] Fix the LSDA that we emit for unknown EH personalities

We should have a single call site entry with no landing pad. This
indicates that no EH action should be taken and the unwinder should
unwind to the next frame.

We currently don't recognize __gxx_personality_seh0 as a known
personality, so we forcibly emit a table, and that table was wrong. This
was filed as PR33220. Now we emit a correct table for that personality.
The next step is to recognize that we can completely skip the table for
this personality.

llvm-svn: 304363

2 files changed, 16 insertions, 5 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
index d72cf592298..4391e80c6cc 100644
--- a/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/AsmPrinter.cpp
@@ -949,6 +949,18 @@ void AsmPrinter::emitFrameAlloc(const MachineInstr &MI) {
                              MCConstantExpr::create(FrameOffset, OutContext));
 }
 
+static bool needFuncLabelsForEHOrDebugInfo(const MachineFunction &MF,
+                                           MachineModuleInfo *MMI) {
+  if (!MF.getLandingPads().empty() || MF.hasEHFunclets() || MMI->hasDebugInfo())
+    return true;
+
+  // We might emit an LSDA anyway if we have an EH personality.
+  const Constant *PerFn = MF.getFunction()->getPersonalityFn();
+  if (!PerFn)
+    return false;
+  return !isNoOpWithoutInvoke(classifyEHPersonality(PerFn));
+}
+
 /// EmitFunctionBody - This method emits the body and trailer for a
 /// function.
 void AsmPrinter::EmitFunctionBody() {
@@ -1076,8 +1088,8 @@ void AsmPrinter::EmitFunctionBody() {
   // Emit target-specific gunk after the function body.
   EmitFunctionBodyEnd();
 
-  if (!MF->getLandingPads().empty() || MMI->hasDebugInfo() ||
-      MF->hasEHFunclets() || MAI->hasDotTypeDotSizeDirective()) {
+  if (needFuncLabelsForEHOrDebugInfo(*MF, MMI) ||
+      MAI->hasDotTypeDotSizeDirective()) {
     // Create a symbol for the end of function.
     CurrentFnEnd = createTempSymbol("func_end");
     OutStreamer->EmitLabel(CurrentFnEnd);
@@ -1402,8 +1414,7 @@ void AsmPrinter::SetupMachineFunction(MachineFunction &MF) {
   CurrentFnBegin = nullptr;
   CurExceptionSym = nullptr;
   bool NeedsLocalForSize = MAI->needsLocalForSize();
-  if (!MF.getLandingPads().empty() || MMI->hasDebugInfo() ||
-      MF.hasEHFunclets() || NeedsLocalForSize) {
+  if (needFuncLabelsForEHOrDebugInfo(MF, MMI) || NeedsLocalForSize) {
     CurrentFnBegin = createTempSymbol("func_begin");
     if (NeedsLocalForSize)
       CurrentFnSymForSize = CurrentFnBegin;
diff --git a/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp b/llvm/lib/CodeGen/AsmPrinter/EHStreamer.cpp
index 0a4a7a06cb2..e14d5be1177 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 && LastLabel != nullptr) {
+  if (SawPotentiallyThrowing && !IsSJLJ) {
     CallSiteEntry Site = { LastLabel, nullptr, nullptr, 0 };
     CallSites.push_back(Site);
   }