diff options
Diffstat (limited to 'lib/CodeGen')
| -rw-r--r-- | lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp | 9 |
1 files changed, 7 insertions, 2 deletions
diff --git a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp index 495418d999..3a25714f07 100644 --- a/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp +++ b/lib/CodeGen/SelectionDAG/SelectionDAGBuilder.cpp @@ -4205,8 +4205,13 @@ isInTailCallPosition(CallSite CS, Attributes CalleeRetAttr, const ReturnInst *Ret = dyn_cast<ReturnInst>(Term); const Function *F = ExitBB->getParent(); - // The block must end in a return statement or an unreachable. - if (!Ret && !isa<UnreachableInst>(Term)) return false; + // The block must end in a return statement. + // FIXME: Disallow tailcall if the block ends in an unreachable for now. + // The way tailcall optimization is currently implemented means it will + // add an epilogue followed by a jump. That is not profitable. Also, if + // the callee is a special function (e.g. longjmp on x86), it can end up + // causing miscompilation that has not been fully understood. + if (!Ret) return false; // Unless we are explicitly forcing tailcall optimization do not tailcall if // the called function is bitcast'ed. The analysis may not be entirely |