[EH] Keep filter clauses for types that have been caught.
The instruction combiner previously removed types from filter clauses in Landing Pad instructions if the type had previously been seen in a catch clause. This is incorrect and prevents unexpected exception handlers from rethrowing the caught type.
Differential Revision: http://reviews.llvm.org/D14669
llvm-svn: 253370
diff --git a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
index 3ae7f08..dbc963a 100644
--- a/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstructionCombining.cpp
@@ -2486,10 +2486,24 @@
SawCatchAll = true;
break;
}
- if (AlreadyCaught.count(TypeInfo))
- // Already caught by an earlier clause, so having it in the filter
- // is pointless.
- continue;
+
+ // Even if we've seen a type in a catch clause, we don't want to
+ // remove it from the filter. An unexpected type handler may be
+ // set up for a call site which throws an exception of the same
+ // type caught. In order for the exception thrown by the unexpected
+ // handler to propogate correctly, the filter must be correctly
+ // described for the call site.
+ //
+ // Example:
+ //
+ // void unexpected() { throw 1;}
+ // void foo() throw (int) {
+ // std::set_unexpected(unexpected);
+ // try {
+ // throw 2.0;
+ // } catch (int i) {}
+ // }
+
// There is no point in having multiple copies of the same typeinfo in
// a filter, so only add it if we didn't already.
if (SeenInFilter.insert(TypeInfo).second)