Update makeLibCall to return both the call and the chain associated with the libcall instead of just the call. This allows us to specify libcalls that return void.

LowerCallTo returns a pair with the return value of the call as the first
element and the chain associated with the return value as the second element. If
we lower a call that has a void return value, LowerCallTo returns an SDValue
with a NULL SDNode and the chain for the call. Thus makeLibCall by just
returning the first value makes it impossible for you to set up the chain so
that the call is not eliminated as dead code.

I also updated all references to makeLibCall to reflect the new return type.

llvm-svn: 188300

1 files changed, 14 insertions, 11 deletions

diff --git a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index e3c63066dec..df672214365 100644
--- a/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -67,10 +67,13 @@ bool TargetLowering::isInTailCallPosition(SelectionDAG &DAG, SDNode *Node,
 
 /// Generate a libcall taking the given operands as arguments and returning a
 /// result of type RetVT.
-SDValue TargetLowering::makeLibCall(SelectionDAG &DAG,
-                                    RTLIB::Libcall LC, EVT RetVT,
-                                    const SDValue *Ops, unsigned NumOps,
-                                    bool isSigned, SDLoc dl) const {
+std::pair<SDValue, SDValue>
+TargetLowering::makeLibCall(SelectionDAG &DAG,
+                            RTLIB::Libcall LC, EVT RetVT,
+                            const SDValue *Ops, unsigned NumOps,
+                            bool isSigned, SDLoc dl,
+                            bool doesNotReturn,
+                            bool isReturnValueUsed) const {
   TargetLowering::ArgListTy Args;
   Args.reserve(NumOps);
 
@@ -89,11 +92,9 @@ SDValue TargetLowering::makeLibCall(SelectionDAG &DAG,
   CallLoweringInfo CLI(DAG.getEntryNode(), RetTy, isSigned, !isSigned, false,
                     false, 0, getLibcallCallingConv(LC),
                     /*isTailCall=*/false,
-                    /*doesNotReturn=*/false, /*isReturnValueUsed=*/true,
-                    Callee, Args, DAG, dl);
-  std::pair<SDValue,SDValue> CallInfo = LowerCallTo(CLI);
-
-  return CallInfo.first;
+                    doesNotReturn, isReturnValueUsed, Callee, Args,
+                    DAG, dl);
+  return LowerCallTo(CLI);
 }
 
 
@@ -183,14 +184,16 @@ void TargetLowering::softenSetCCOperands(SelectionDAG &DAG, EVT VT,
   // Use the target specific return value for comparions lib calls.
   EVT RetVT = getCmpLibcallReturnType();
   SDValue Ops[2] = { NewLHS, NewRHS };
-  NewLHS = makeLibCall(DAG, LC1, RetVT, Ops, 2, false/*sign irrelevant*/, dl);
+  NewLHS = makeLibCall(DAG, LC1, RetVT, Ops, 2, false/*sign irrelevant*/,
+                       dl).first;
   NewRHS = DAG.getConstant(0, RetVT);
   CCCode = getCmpLibcallCC(LC1);
   if (LC2 != RTLIB::UNKNOWN_LIBCALL) {
     SDValue Tmp = DAG.getNode(ISD::SETCC, dl,
                               getSetCCResultType(*DAG.getContext(), RetVT),
                               NewLHS, NewRHS, DAG.getCondCode(CCCode));
-    NewLHS = makeLibCall(DAG, LC2, RetVT, Ops, 2, false/*sign irrelevant*/, dl);
+    NewLHS = makeLibCall(DAG, LC2, RetVT, Ops, 2, false/*sign irrelevant*/,
+                         dl).first;
     NewLHS = DAG.getNode(ISD::SETCC, dl,
                          getSetCCResultType(*DAG.getContext(), RetVT), NewLHS,
                          NewRHS, DAG.getCondCode(getCmpLibcallCC(LC2)));