Don't promote asynch EH invokes of nounwind functions to calls

If the landingpad of the invoke is using a personality function that
catches asynch exceptions, then it can catch a trap.

Also add some landingpads to invalid LLVM IR test cases that lack them.

Over-the-shoulder reviewed by David Majnemer.

llvm-svn: 228782

1 files changed, 24 insertions, 1 deletions

diff --git a/llvm/lib/Analysis/LibCallSemantics.cpp b/llvm/lib/Analysis/LibCallSemantics.cpp
index 3a345c45d07..6c2ebdb4594 100644
--- a/llvm/lib/Analysis/LibCallSemantics.cpp
+++ b/llvm/lib/Analysis/LibCallSemantics.cpp
@@ -64,7 +64,7 @@ LibCallInfo::getFunctionInfo(const Function *F) const {
 
 /// See if the given exception handling personality function is one that we
 /// understand.  If so, return a description of it; otherwise return Unknown.
-EHPersonality llvm::ClassifyEHPersonality(Value *Pers) {
+EHPersonality llvm::classifyEHPersonality(Value *Pers) {
   Function *F = dyn_cast<Function>(Pers->stripPointerCasts());
   if (!F)
     return EHPersonality::Unknown;
@@ -73,7 +73,30 @@ EHPersonality llvm::ClassifyEHPersonality(Value *Pers) {
     .Case("__gxx_personality_v0",  EHPersonality::GNU_CXX)
     .Case("__gcc_personality_v0",  EHPersonality::GNU_C)
     .Case("__objc_personality_v0", EHPersonality::GNU_ObjC)
+    .Case("__except_handler3",     EHPersonality::MSVC_X86SEH)
+    .Case("__except_handler4",     EHPersonality::MSVC_X86SEH)
     .Case("__C_specific_handler",  EHPersonality::MSVC_Win64SEH)
     .Case("__CxxFrameHandler3",    EHPersonality::MSVC_CXX)
     .Default(EHPersonality::Unknown);
 }
+
+bool llvm::isAsynchronousEHPersonality(EHPersonality Pers) {
+  // The two SEH personality functions can catch asynch exceptions. We assume
+  // unknown personalities don't catch asynch exceptions.
+  switch (Pers) {
+  case EHPersonality::MSVC_X86SEH:
+  case EHPersonality::MSVC_Win64SEH:
+    return true;
+  default: return false;
+  }
+  llvm_unreachable("invalid enum");
+}
+
+bool llvm::canSimplifyInvokeNoUnwind(const InvokeInst *II) {
+  const LandingPadInst *LP = II->getLandingPadInst();
+  EHPersonality Personality = classifyEHPersonality(LP->getPersonalityFn());
+  // We can't simplify any invokes to nounwind functions if the personality
+  // function wants to catch asynch exceptions.  The nounwind attribute only
+  // implies that the function does not throw synchronous exceptions.
+  return !isAsynchronousEHPersonality(Personality);
+}