llvm dev - May 2012 - [LLVMdev] Changes to TargetLowering::{LowerCallTo,LowerCall}

A change has just been committed that changes the interface for
TargetLowering::LowerCallTo and TargetLowering::LowerCall.  Instead of passing a
mess of parameters to these functions, a new structure has been created that
encapsulates these parameters.  The motivation is that additional fields can be
added to this structure (with appropriate changes to SelectionDAGBuilder for
populating the new fields) without forcing an ABI change on each and every
target.  In-tree targets have been updated accordingly, so no change is
required.  However, if you have an out-of-tree target that is following trunk,
please be aware that this *will* break your build.  Please see any in-tree
target for the new interface and how to access the values that used to be
available as individual function parameters.



As a quick example, the ARM implementation for LowerCall is now:



SDValue

ARMTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,

                             SmallVectorImpl<SDValue> &InVals) const {

  SelectionDAG &DAG                     = CLI.DAG;

  DebugLoc &dl                          = CLI.DL;

  SmallVector<ISD::OutputArg, 32> &Outs = CLI.Outs;

  SmallVector<SDValue, 32> &OutVals     = CLI.OutVals;

  SmallVector<ISD::InputArg, 32> &Ins   = CLI.Ins;

  SDValue Chain                         = CLI.Chain;

  SDValue Callee                        = CLI.Callee;

  bool &isTailCall                      = CLI.IsTailCall;

  CallingConv::ID CallConv              = CLI.CallConv;

  bool doesNotRet                       = CLI.DoesNotReturn;

  bool isVarArg                         = CLI.IsVarArg;





The CallLoweringInfo struct now contains all parameters that were originally
available as parameters.  The InVals vector was left as a parameter since it is
the responsibility of the LowerCall implementation to fill it and does not
represent input information about the call (unlike IsTailCall which is an in/out
parameter, and hence added to the new struct).







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