[SimplifyCFG] Stop inserting calls to llvm.trap for UB

SimplifyCFG had logic to insert calls to llvm.trap for two very
particular IR patterns: stores and invokes of undef/null.

While InstCombine canonicalizes certain undefined behavior IR patterns
to stores of undef, phase ordering means that this cannot be relied upon
in general.

There are much better tools than llvm.trap: UBSan and ASan.

N.B. I could be argued into reverting this change if a clear argument as
to why it is important that we synthesize llvm.trap for stores, I'd be
hard pressed to see why it'd be useful for invokes...

llvm-svn: 273778

1 files changed, 3 insertions, 3 deletions

diff --git a/llvm/lib/CodeGen/WinEHPrepare.cpp b/llvm/lib/CodeGen/WinEHPrepare.cpp
index 041fb7b912b..a8e089a23d2 100644
--- a/llvm/lib/CodeGen/WinEHPrepare.cpp
+++ b/llvm/lib/CodeGen/WinEHPrepare.cpp
@@ -963,9 +963,9 @@ void WinEHPrepare::removeImplausibleInstructions(Function &F) {
           BasicBlock::iterator CallI =
               std::prev(BB->getTerminator()->getIterator());
           auto *CI = cast<CallInst>(&*CallI);
-          changeToUnreachable(CI, /*UseLLVMTrap=*/false);
+          changeToUnreachable(CI);
         } else {
-          changeToUnreachable(&I, /*UseLLVMTrap=*/false);
+          changeToUnreachable(&I);
         }
 
         // There are no more instructions in the block (except for unreachable),
@@ -986,7 +986,7 @@ void WinEHPrepare::removeImplausibleInstructions(Function &F) {
         IsUnreachableCleanupret = CRI->getCleanupPad() != CleanupPad;
       if (IsUnreachableRet || IsUnreachableCatchret ||
           IsUnreachableCleanupret) {
-        changeToUnreachable(TI, /*UseLLVMTrap=*/false);
+        changeToUnreachable(TI);
       } else if (isa<InvokeInst>(TI)) {
         if (Personality == EHPersonality::MSVC_CXX && CleanupPad) {
           // Invokes within a cleanuppad for the MSVC++ personality never