[WinEH] Prevent EH state numbering from skipping nested cleanup pads that never return

Differential Revision: http://reviews.llvm.org/D17208

llvm-svn: 260733

1 files changed, 14 insertions, 6 deletions

diff --git a/llvm/lib/CodeGen/WinEHPrepare.cpp b/llvm/lib/CodeGen/WinEHPrepare.cpp
index 281fe934292..3e16a25f79e 100644
--- a/llvm/lib/CodeGen/WinEHPrepare.cpp
+++ b/llvm/lib/CodeGen/WinEHPrepare.cpp
@@ -257,10 +257,14 @@ static void calculateCXXStateNumbers(WinEHFuncInfo &FuncInfo,
         if (auto *InnerCatchSwitch = dyn_cast<CatchSwitchInst>(UserI))
           if (InnerCatchSwitch->getUnwindDest() == CatchSwitch->getUnwindDest())
             calculateCXXStateNumbers(FuncInfo, UserI, CatchLow);
-        if (auto *InnerCleanupPad = dyn_cast<CleanupPadInst>(UserI))
-          if (getCleanupRetUnwindDest(InnerCleanupPad) ==
-              CatchSwitch->getUnwindDest())
+        if (auto *InnerCleanupPad = dyn_cast<CleanupPadInst>(UserI)) {
+          BasicBlock *UnwindDest = getCleanupRetUnwindDest(InnerCleanupPad);
+          // If a nested cleanup pad reports a null unwind destination and the
+          // enclosing catch pad doesn't it must be post-dominated by an
+          // unreachable instruction.
+          if (!UnwindDest || UnwindDest == CatchSwitch->getUnwindDest())
             calculateCXXStateNumbers(FuncInfo, UserI, CatchLow);
+        }
       }
     }
     int CatchHigh = FuncInfo.getLastStateNumber();
@@ -360,10 +364,14 @@ static void calculateSEHStateNumbers(WinEHFuncInfo &FuncInfo,
       if (auto *InnerCatchSwitch = dyn_cast<CatchSwitchInst>(UserI))
         if (InnerCatchSwitch->getUnwindDest() == CatchSwitch->getUnwindDest())
           calculateSEHStateNumbers(FuncInfo, UserI, ParentState);
-      if (auto *InnerCleanupPad = dyn_cast<CleanupPadInst>(UserI))
-        if (getCleanupRetUnwindDest(InnerCleanupPad) ==
-            CatchSwitch->getUnwindDest())
+      if (auto *InnerCleanupPad = dyn_cast<CleanupPadInst>(UserI)) {
+        BasicBlock *UnwindDest = getCleanupRetUnwindDest(InnerCleanupPad);
+        // If a nested cleanup pad reports a null unwind destination and the
+        // enclosing catch pad doesn't it must be post-dominated by an
+        // unreachable instruction.
+        if (!UnwindDest || UnwindDest == CatchSwitch->getUnwindDest())
           calculateSEHStateNumbers(FuncInfo, UserI, ParentState);
+      }
     }
   } else {
     auto *CleanupPad = cast<CleanupPadInst>(FirstNonPHI);