From 36ef0d54cfddf31cd48816e78ab4db73b31a6c1d Mon Sep 17 00:00:00 2001 From: Richard Smith Date: Thu, 4 Oct 2012 23:52:29 +0000 Subject: 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 --- lib/CodeGen/CodeGenFunction.cpp | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'lib/CodeGen/CodeGenFunction.cpp') diff --git a/lib/CodeGen/CodeGenFunction.cpp b/lib/CodeGen/CodeGenFunction.cpp index 1d02861ed7..5c0247a33f 100644 --- a/lib/CodeGen/CodeGenFunction.cpp +++ b/lib/CodeGen/CodeGenFunction.cpp @@ -535,6 +535,20 @@ void CodeGenFunction::GenerateCode(GlobalDecl GD, llvm::Function *Fn, 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()); -- cgit v1.2.3-18-g5258