Commit 95e705db authored by Tanya Lattner's avatar Tanya Lattner
Browse files

Merge 98561 from mainline. 

Avoid sibcall optimization if either caller or callee is using sret semantics.

llvm-svn: 99290
parent 18d41baa

llvm/lib/Target/X86/X86ISelLowering.cpp

+10 −3
Original line number Diff line number Diff line
@@ -1477,7 +1477,6 @@ X86TargetLowering::LowerFormalArguments(SDValue Chain, 
                                        DebugLoc dl,

                                        SelectionDAG &DAG,

                                        SmallVectorImpl<SDValue> &InVals) {



  MachineFunction &MF = DAG.getMachineFunction();

  X86MachineFunctionInfo *FuncInfo = MF.getInfo<X86MachineFunctionInfo>();
@@ -1779,7 +1778,8 @@ X86TargetLowering::LowerCall(SDValue Chain, SDValue Callee, 


  if (isTailCall) {

    // Check if it's really possible to do a tail call.

    isTailCall = IsEligibleForTailCallOptimization(Callee, CallConv, isVarArg,

    isTailCall = IsEligibleForTailCallOptimization(Callee, CallConv,

                    isVarArg, IsStructRet, MF.getFunction()->hasStructRetAttr(),

                                                   Outs, Ins, DAG);



    // Sibcalls are automatically detected tailcalls which do not require
@@ -2297,6 +2297,8 @@ bool 
X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee,

                                                     CallingConv::ID CalleeCC,

                                                     bool isVarArg,

                                                     bool isCalleeStructRet,

                                                     bool isCallerStructRet,

                                    const SmallVectorImpl<ISD::OutputArg> &Outs,

                                    const SmallVectorImpl<ISD::InputArg> &Ins,

                                                     SelectionDAG& DAG) const {
@@ -2316,10 +2318,15 @@ X86TargetLowering::IsEligibleForTailCallOptimization(SDValue Callee, 
  // Look for obvious safe cases to perform tail call optimization that does not

  // requite ABI changes. This is what gcc calls sibcall.



  // Do not tail call optimize vararg calls for now.

  // Do not sibcall optimize vararg calls for now.

  if (isVarArg)

    return false;



  // Also avoid sibcall optimization if either caller or callee uses struct

  // return semantics.

  if (isCalleeStructRet || isCallerStructRet)

    return false;



  // If the callee takes no arguments then go on to check the results of the

  // call.

  if (!Outs.empty()) {

llvm/lib/Target/X86/X86ISelLowering.h

+2 −0
Original line number Diff line number Diff line
@@ -637,6 +637,8 @@ namespace llvm { 
    bool IsEligibleForTailCallOptimization(SDValue Callee,

                                           CallingConv::ID CalleeCC,

                                           bool isVarArg,

                                           bool isCalleeStructRet,

                                           bool isCallerStructRet,

                                    const SmallVectorImpl<ISD::OutputArg> &Outs,

                                    const SmallVectorImpl<ISD::InputArg> &Ins,

                                           SelectionDAG& DAG) const;