If we flow off the end of a value-returning function:
- outside C++, return undef (behavior is not undefined unless the value is used)
- in C++, with -fcatch-undefined-behavior, perform an appropriate trap
- in C++, produce an 'unreachable' (behavior is undefined immediately)
git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@165273 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp
index 1d02861..5c0247a 100644
--- a/lib/CodeGen/CodeGenFunction.cpp
+++ b/lib/CodeGen/CodeGenFunction.cpp
@@ -535,6 +535,20 @@
else
EmitFunctionBody(Args);
+ // C++11 [stmt.return]p2:
+ // Flowing off the end of a function [...] results in undefined behavior in
+ // a value-returning function.
+ // C11 6.9.1p12:
+ // If the '}' that terminates a function is reached, and the value of the
+ // function call is used by the caller, the behavior is undefined.
+ if (getContext().getLangOpts().CPlusPlus && !FD->hasImplicitReturnZero() &&
+ !FD->getResultType()->isVoidType() && Builder.GetInsertBlock()) {
+ if (CatchUndefined)
+ EmitCheck(Builder.getFalse());
+ Builder.CreateUnreachable();
+ Builder.ClearInsertionPoint();
+ }
+
// Emit the standard function epilogue.
FinishFunction(BodyRange.getEnd());