commit aff703a2ca704a55eadf024497bc5914ed089372
author Keno Fischer <kfischer@college.harvard.edu> Tue Jul 14 19:22:51 2015 +0000
committer Keno Fischer <kfischer@college.harvard.edu> Tue Jul 14 19:22:51 2015 +0000
tree c7b7ff39807894a23917ff6c8be033aa08742017
parent fea7765219c18743800785d8c58290695f661594

[CodeGen] Force emission of personality directive if explicitly specified

Summary:
Before this change, personality directives were not emitted
if there was no invoke left in the function (of course until
recently this also meant that we couldn't know what
the personality actually was). This patch forces personality directives
to still be emitted, unless it is known to be a noop in the absence of
invokes, or the user explicitly specified `nounwind` (and not
`uwtable`) on the function.

Reviewers: majnemer, rnk

Subscribers: rnk, llvm-commits

Differential Revision: http://reviews.llvm.org/D10884

llvm-svn: 242185

llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp b/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
index 0bc873e..2c212c7 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfCFIException.cpp
@@ -89,6 +89,7 @@
 
 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 @@
 
   const TargetLoweringObjectFile &TLOF = Asm->getObjFileLowering();
   unsigned PerEncoding = TLOF.getPersonalityEncoding();
-  const Function *Per = MMI->getPersonality();
+  const Function *Per = nullptr;
+  if (F->hasPersonalityFn())
+    Per = dyn_cast<Function>(F->getPersonalityFn()->stripPointerCasts());
+  assert(!MMI->getPersonality() || Per == MMI->getPersonality());
 
-  shouldEmitPersonality = hasLandingPads &&
-    PerEncoding != dwarf::DW_EH_PE_omit && Per;
+  // 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 @@
   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);