From e71d60d2c948bef21443c3370a9922a2f58bcc3a Mon Sep 17 00:00:00 2001
From: John McCall <rjmccall@apple.com>
Date: Tue, 5 Oct 2010 20:48:15 +0000
Subject: [PATCH] Teach PopCleanupBlock to correctly handle the possibility of
 branching through a EH-only cleanup as part of a fallthrough branch-through. 
 That this happens for this test case is actually a separate bug.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@115668 91177308-0d34-0410-b5e6-96231b3b80d8
---
 lib/CodeGen/CodeGenFunction.cpp | 23 ++++++++++++++---------
 test/CodeGenCXX/goto.cpp        | 29 +++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+), 9 deletions(-)
 create mode 100644 test/CodeGenCXX/goto.cpp

diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index 043195cecf..56dccc1c0a 100644
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -846,26 +846,31 @@ void CodeGenFunction::PopCleanupBlock(bool FallthroughIsBranchThrough) {
   llvm::BasicBlock *FallthroughSource = Builder.GetInsertBlock();
   bool HasFallthrough = (FallthroughSource != 0 && IsActive);
 
-  // As a kindof crazy internal case, branch-through fall-throughs
-  // leave the insertion point set to the end of the last cleanup.
+  // Branch-through fall-throughs leave the insertion point set to the
+  // end of the last cleanup, which points to the current scope.  The
+  // rest of IR gen doesn't need to worry about this; it only happens
+  // during the execution of PopCleanupBlocks().
   bool HasPrebranchedFallthrough =
     (FallthroughSource && FallthroughSource->getTerminator());
 
+  // If this is a normal cleanup, then having a prebranched
+  // fallthrough implies that the fallthrough source unconditionally
+  // jumps here.
+  assert(!Scope.isNormalCleanup() || !HasPrebranchedFallthrough ||
+         (Scope.getNormalBlock() &&
+          FallthroughSource->getTerminator()->getSuccessor(0)
+            == Scope.getNormalBlock()));
+
   bool RequiresNormalCleanup = false;
   if (Scope.isNormalCleanup() &&
       (HasFixups || HasExistingBranches || HasFallthrough)) {
     RequiresNormalCleanup = true;
   }
 
-  assert(!HasPrebranchedFallthrough || RequiresNormalCleanup || !IsActive);
-  assert(!HasPrebranchedFallthrough ||
-         (Scope.isNormalCleanup() && Scope.getNormalBlock() &&
-          FallthroughSource->getTerminator()->getSuccessor(0)
-            == Scope.getNormalBlock()));
-
   // Even if we don't need the normal cleanup, we might still have
   // prebranched fallthrough to worry about.
-  if (!RequiresNormalCleanup && HasPrebranchedFallthrough) {
+  if (Scope.isNormalCleanup() && !RequiresNormalCleanup &&
+      HasPrebranchedFallthrough) {
     assert(!IsActive);
 
     llvm::BasicBlock *NormalEntry = Scope.getNormalBlock();
diff --git a/test/CodeGenCXX/goto.cpp b/test/CodeGenCXX/goto.cpp
new file mode 100644
index 0000000000..7ebb72f54a
--- /dev/null
+++ b/test/CodeGenCXX/goto.cpp
@@ -0,0 +1,29 @@
+// RUN: %clang-cc1 %s -fexceptions
+
+// Reduced from a crash on boost::interprocess's node_allocator_test.cpp.
+namespace test0 {
+  struct A { A(); ~A(); };
+  struct V { V(const A &a = A()); ~V(); };
+
+  template<int X> int vector_test()
+  {
+   A process_name;
+   try {
+     A segment;
+
+     V *stdvector = new V();
+
+     int x = 5, y = 7;
+     if(x == y) return 1;
+   }
+   catch(int ex){
+     return 1;
+   }
+   return 0;
+}
+
+int main ()
+{
+  return vector_test<0>();
+}
+}
-- 
2.40.0