SjLj EH could produce a machine basic block that legitimately has more than one

landing pad as its successor.

SjLj exception handling jumps to the correct landing pad via a switch statement
that's generated right before code-gen. Loosen the constraint in the machine
instruction verifier to allow for this. Note, this isn't the most rigorous check
since we cannot determine where that switch statement came from. But it's
marginally better than turning this check off when SjLj exceptions are used.
<rdar://problem/9187612>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@130881 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 9 insertions, 1 deletions

diff --git a/lib/CodeGen/MachineVerifier.cpp b/lib/CodeGen/MachineVerifier.cpp
index f95f411..fa9092b 100644
--- a/lib/CodeGen/MachineVerifier.cpp
+++ b/lib/CodeGen/MachineVerifier.cpp
@@ -23,6 +23,7 @@
 // the verifier errors.
 //===----------------------------------------------------------------------===//
 
+#include "llvm/Instructions.h"
 #include "llvm/Function.h"
 #include "llvm/CodeGen/LiveIntervalAnalysis.h"
 #include "llvm/CodeGen/LiveVariables.h"
@@ -32,6 +33,7 @@
 #include "llvm/CodeGen/MachineMemOperand.h"
 #include "llvm/CodeGen/MachineRegisterInfo.h"
 #include "llvm/CodeGen/Passes.h"
+#include "llvm/MC/MCAsmInfo.h"
 #include "llvm/Target/TargetMachine.h"
 #include "llvm/Target/TargetRegisterInfo.h"
 #include "llvm/Target/TargetInstrInfo.h"
@@ -394,7 +396,13 @@ MachineVerifier::visitMachineBasicBlockBefore(const MachineBasicBlock *MBB) {
     if ((*I)->isLandingPad())
       LandingPadSuccs.insert(*I);
   }
-  if (LandingPadSuccs.size() > 1)
+
+  const MCAsmInfo *AsmInfo = TM->getMCAsmInfo();
+  const BasicBlock *BB = MBB->getBasicBlock();
+  if (LandingPadSuccs.size() > 1 &&
+      !(AsmInfo &&
+        AsmInfo->getExceptionHandlingType() == ExceptionHandling::SjLj &&
+        BB && isa<SwitchInst>(BB->getTerminator())))
     report("MBB has more than one landing pad successor", MBB);
 
   // Call AnalyzeBranch. If it succeeds, there several more conditions to check.