isTailCall = IsEligibleForTailCallOptimization(Callee, CallConv,
isVarArg, isStructRet, MF.getFunction()->hasStructRetAttr(),
Outs, OutVals, Ins, DAG);
+ if (!isTailCall && CLI.CS && CLI.CS->isMustTailCall())
+ report_fatal_error("failed to perform tail call elimination on a call "
+ "site marked musttail");
// We don't support GuaranteedTailCallOpt for ARM, only automatically
// detected sibcalls.
if (isTailCall) {