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

5 files changed, 32 insertions, 5 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);
+}
diff --git a/llvm/lib/CodeGen/WinEHPrepare.cpp b/llvm/lib/CodeGen/WinEHPrepare.cpp
index c608bb0a31e..b4019b48617 100644
--- a/llvm/lib/CodeGen/WinEHPrepare.cpp
+++ b/llvm/lib/CodeGen/WinEHPrepare.cpp
@@ -75,7 +75,7 @@ bool WinEHPrepare::runOnFunction(Function &Fn) {
     return false;
 
   // Classify the personality to see what kind of preparation we need.
-  EHPersonality Pers = ClassifyEHPersonality(LPads.back()->getPersonalityFn());
+  EHPersonality Pers = classifyEHPersonality(LPads.back()->getPersonalityFn());
 
   // Delegate through to the DWARF pass if this is unrecognized.
   if (!isMSVCPersonality(Pers))
diff --git a/llvm/lib/Transforms/IPO/PruneEH.cpp b/llvm/lib/Transforms/IPO/PruneEH.cpp
index 7bd4ce12860..1943b930cbf 100644
--- a/llvm/lib/Transforms/IPO/PruneEH.cpp
+++ b/llvm/lib/Transforms/IPO/PruneEH.cpp
@@ -18,8 +18,10 @@
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/Support/raw_ostream.h"
 #include "llvm/Analysis/CallGraph.h"
 #include "llvm/Analysis/CallGraphSCCPass.h"
+#include "llvm/Analysis/LibCallSemantics.h"
 #include "llvm/IR/CFG.h"
 #include "llvm/IR/Constants.h"
 #include "llvm/IR/Function.h"
@@ -175,7 +177,7 @@ bool PruneEH::SimplifyFunction(Function *F) {
   bool MadeChange = false;
   for (Function::iterator BB = F->begin(), E = F->end(); BB != E; ++BB) {
     if (InvokeInst *II = dyn_cast<InvokeInst>(BB->getTerminator()))
-      if (II->doesNotThrow()) {
+      if (II->doesNotThrow() && canSimplifyInvokeNoUnwind(II)) {
         SmallVector<Value*, 8> Args(II->op_begin(), II->op_end() - 3);
         // Insert a call instruction before the invoke.
         CallInst *Call = CallInst::Create(II->getCalledValue(), Args, "", II);
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 3cfcc90a8ed..ffc8ff5b16c 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2275,6 +2275,7 @@ static bool isCatchAll(EHPersonality Personality, Constant *TypeInfo) {
     return false;
   case EHPersonality::GNU_CXX:
   case EHPersonality::GNU_ObjC:
+  case EHPersonality::MSVC_X86SEH:
   case EHPersonality::MSVC_Win64SEH:
   case EHPersonality::MSVC_CXX:
     return TypeInfo->isNullValue();
@@ -2293,7 +2294,7 @@ Instruction *InstCombiner::visitLandingPadInst(LandingPadInst &LI) {
   // The logic here should be correct for any real-world personality function.
   // However if that turns out not to be true, the offending logic can always
   // be conditioned on the personality function, like the catch-all logic is.
-  EHPersonality Personality = ClassifyEHPersonality(LI.getPersonalityFn());
+  EHPersonality Personality = classifyEHPersonality(LI.getPersonalityFn());
 
   // Simplify the list of clauses, eg by removing repeated catch clauses
   // (these are often created by inlining).
diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index b8c0a7e47b5..48305684721 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -17,6 +17,7 @@
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SmallPtrSet.h"
 #include "llvm/ADT/Statistic.h"
+#include "llvm/Analysis/LibCallSemantics.h"
 #include "llvm/Analysis/InstructionSimplify.h"
 #include "llvm/Analysis/MemoryBuiltins.h"
 #include "llvm/Analysis/ValueTracking.h"
@@ -1260,7 +1261,7 @@ static bool markAliveBlocks(BasicBlock *BB,
       if (isa<ConstantPointerNull>(Callee) || isa<UndefValue>(Callee)) {
         changeToUnreachable(II, true);
         Changed = true;
-      } else if (II->doesNotThrow()) {
+      } else if (II->doesNotThrow() && canSimplifyInvokeNoUnwind(II)) {
         if (II->use_empty() && II->onlyReadsMemory()) {
           // jump to the normal destination branch.
           BranchInst::Create(II->getNormalDest(), II);