When a failed dynamic_cast<T&> (which is an lvalue) results in a

throw, it should use invoke when needed. The fixes the
Boost.Statechrt failures that motivated PR7132, but there are a few
side issues to tackle as well.

llvm-svn: 103803

3 files changed, 26 insertions, 8 deletions

diff --git a/clang/lib/CodeGen/CGExprCXX.cpp b/clang/lib/CodeGen/CGExprCXX.cpp
index 2b0938ab84b..3a2882e24b6 100644
--- a/clang/lib/CodeGen/CGExprCXX.cpp
+++ b/clang/lib/CodeGen/CGExprCXX.cpp
@@ -867,6 +867,8 @@ llvm::Value *CodeGenFunction::EmitDynamicCast(llvm::Value *V,
       ToVoid = true;
   } else {
     LTy = LTy->getPointerTo();
+    
+    // FIXME: What if exceptions are disabled?
     ThrowOnBad = true;
   }
 
@@ -933,15 +935,21 @@ llvm::Value *CodeGenFunction::EmitDynamicCast(llvm::Value *V,
 
     if (ThrowOnBad) {
       BadCastBlock = createBasicBlock();
-
       Builder.CreateCondBr(Builder.CreateIsNotNull(V), ContBlock, BadCastBlock);
       EmitBlock(BadCastBlock);
-      /// Call __cxa_bad_cast
+      /// Invoke __cxa_bad_cast
       ResultType = llvm::Type::getVoidTy(VMContext);
       const llvm::FunctionType *FBadTy;
       FBadTy = llvm::FunctionType::get(ResultType, false);
       llvm::Value *F = CGM.CreateRuntimeFunction(FBadTy, "__cxa_bad_cast");
-      Builder.CreateCall(F)->setDoesNotReturn();
+      if (llvm::BasicBlock *InvokeDest = getInvokeDest()) {
+        llvm::BasicBlock *Cont = createBasicBlock("invoke.cont");
+        Builder.CreateInvoke(F, Cont, InvokeDest)->setDoesNotReturn();
+        EmitBlock(Cont);
+      } else {
+        // FIXME: Does this ever make sense?
+        Builder.CreateCall(F)->setDoesNotReturn();
+      }
       Builder.CreateUnreachable();
     }
   }
diff --git a/clang/test/CodeGenCXX/dynamic-cast.cpp b/clang/test/CodeGenCXX/dynamic-cast.cpp
index aeb2a64157b..572b521c925 100644
--- a/clang/test/CodeGenCXX/dynamic-cast.cpp
+++ b/clang/test/CodeGenCXX/dynamic-cast.cpp
@@ -1,8 +1,20 @@
-// RUN: %clang_cc1 %s -emit-llvm-only
-
+// RUN: %clang_cc1 %s -triple x86_64-apple-darwin10 -emit-llvm -fexceptions -o - | FileCheck %s
+#include <typeinfo>
 struct A { virtual void f(); };
 struct B : A { };
 
+// CHECK: {{define.*@_Z1fP1A}}
+B fail;
 const B& f(A *a) {
-  return dynamic_cast<const B&>(*a);
+  try {
+    // CHECK: call i8* @__dynamic_cast
+    // CHECK: br i1
+    // CHECK: invoke void @__cxa_bad_cast() noreturn
+    return dynamic_cast<const B&>(*a);
+  } catch (std::bad_cast&) {
+    // CHECK: call i8* @llvm.eh.exception
+    // CHECK: {{call.*llvm.eh.selector.*_ZTISt8bad_cast}}
+    // CHECK: {{call i32 @llvm.eh.typeid.for.*@_ZTISt8bad_cast}}
+  }
+  return fail;
 }
diff --git a/clang/test/CodeGenCXX/dyncast.cpp b/clang/test/CodeGenCXX/dyncast.cpp
index 127cdd89683..906d44b3c5e 100644
--- a/clang/test/CodeGenCXX/dyncast.cpp
+++ b/clang/test/CodeGenCXX/dyncast.cpp
@@ -20,8 +20,6 @@ extern "C" int printf(const char *str...);
 void test1() {
   test1_B* bp = (test1_B*)&test1_d;
   test1_A* ap = &test1_d;
-  // This throws
-  //  test1_D&  dr = dynamic_cast<D&>(*bp);
   test1_D* dp = dynamic_cast<test1_D*>(bp);
   S(dp == 0, 1);
   ap = dynamic_cast<test1_A*>(bp);