Expand DYNAMIC_STACKALLOC nodes rather than doing custom-lowering.

The frame object which points to the dynamically allocated area will not be
needed after changes are made to cease reserving call frames.



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@161076 91177308-0d34-0410-b5e6-96231b3b80d8

4 files changed, 6 insertions, 66 deletions

diff --git a/lib/Target/Mips/MipsISelLowering.cpp b/lib/Target/Mips/MipsISelLowering.cpp
index e10061a9ea..c5207c6737 100644
--- a/lib/Target/Mips/MipsISelLowering.cpp
+++ b/lib/Target/Mips/MipsISelLowering.cpp
@@ -157,7 +157,6 @@ MipsTargetLowering(MipsTargetMachine &TM)
   setOperationAction(ISD::SETCC,              MVT::f32,   Custom);
   setOperationAction(ISD::SETCC,              MVT::f64,   Custom);
   setOperationAction(ISD::BRCOND,             MVT::Other, Custom);
-  setOperationAction(ISD::DYNAMIC_STACKALLOC, MVT::i32,   Custom);
   setOperationAction(ISD::VASTART,            MVT::Other, Custom);
   setOperationAction(ISD::FCOPYSIGN,          MVT::f32,   Custom);
   setOperationAction(ISD::FCOPYSIGN,          MVT::f64,   Custom);
@@ -178,7 +177,6 @@ MipsTargetLowering(MipsTargetMachine &TM)
     setOperationAction(ISD::JumpTable,          MVT::i64,   Custom);
     setOperationAction(ISD::ConstantPool,       MVT::i64,   Custom);
     setOperationAction(ISD::SELECT,             MVT::i64,   Custom);
-    setOperationAction(ISD::DYNAMIC_STACKALLOC, MVT::i64,   Custom);
     setOperationAction(ISD::LOAD,               MVT::i64,   Custom);
     setOperationAction(ISD::STORE,              MVT::i64,   Custom);
   }
@@ -217,6 +215,8 @@ MipsTargetLowering(MipsTargetMachine &TM)
   setOperationAction(ISD::CTLZ_ZERO_UNDEF,   MVT::i64,   Expand);
   setOperationAction(ISD::ROTL,              MVT::i32,   Expand);
   setOperationAction(ISD::ROTL,              MVT::i64,   Expand);
+  setOperationAction(ISD::DYNAMIC_STACKALLOC, MVT::i32,  Expand);
+  setOperationAction(ISD::DYNAMIC_STACKALLOC, MVT::i64,  Expand);
 
   if (!Subtarget->hasMips32r2())
     setOperationAction(ISD::ROTR, MVT::i32,   Expand);
@@ -792,7 +792,6 @@ LowerOperation(SDValue Op, SelectionDAG &DAG) const
   {
     case ISD::BRCOND:             return LowerBRCOND(Op, DAG);
     case ISD::ConstantPool:       return LowerConstantPool(Op, DAG);
-    case ISD::DYNAMIC_STACKALLOC: return LowerDYNAMIC_STACKALLOC(Op, DAG);
     case ISD::GlobalAddress:      return LowerGlobalAddress(Op, DAG);
     case ISD::BlockAddress:       return LowerBlockAddress(Op, DAG);
     case ISD::GlobalTLSAddress:   return LowerGlobalTLSAddress(Op, DAG);
@@ -1502,42 +1501,6 @@ MipsTargetLowering::EmitAtomicCmpSwapPartword(MachineInstr *MI,
 //  Misc Lower Operation implementation
 //===----------------------------------------------------------------------===//
 SDValue MipsTargetLowering::
-LowerDYNAMIC_STACKALLOC(SDValue Op, SelectionDAG &DAG) const
-{
-  MachineFunction &MF = DAG.getMachineFunction();
-  MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
-  unsigned SP = IsN64 ? Mips::SP_64 : Mips::SP;
-
-  assert(getTargetMachine().getFrameLowering()->getStackAlignment() >=
-         cast<ConstantSDNode>(Op.getOperand(2).getNode())->getZExtValue() &&
-         "Cannot lower if the alignment of the allocated space is larger than \
-          that of the stack.");
-
-  SDValue Chain = Op.getOperand(0);
-  SDValue Size = Op.getOperand(1);
-  DebugLoc dl = Op.getDebugLoc();
-
-  // Get a reference from Mips stack pointer
-  SDValue StackPointer = DAG.getCopyFromReg(Chain, dl, SP, getPointerTy());
-
-  // Subtract the dynamic size from the actual stack size to
-  // obtain the new stack size.
-  SDValue Sub = DAG.getNode(ISD::SUB, dl, getPointerTy(), StackPointer, Size);
-
-  // The Sub result contains the new stack start address, so it
-  // must be placed in the stack pointer register.
-  Chain = DAG.getCopyToReg(StackPointer.getValue(1), dl, SP, Sub, SDValue());
-
-  // This node always has two return values: a new stack pointer
-  // value and a chain
-  SDVTList VTLs = DAG.getVTList(getPointerTy(), MVT::Other);
-  SDValue Ptr = DAG.getFrameIndex(MipsFI->getDynAllocFI(), getPointerTy());
-  SDValue Ops[] = { Chain, Ptr, Chain.getValue(1) };
-
-  return DAG.getNode(MipsISD::DynAlloc, dl, VTLs, Ops, 3);
-}
-
-SDValue MipsTargetLowering::
 LowerBRCOND(SDValue Op, SelectionDAG &DAG) const
 {
   // The first operand is the chain, the second is the condition, the third is
@@ -2691,19 +2654,9 @@ MipsTargetLowering::LowerCall(TargetLowering::CallLoweringInfo &CLI,
                                         IsN64 ? Mips::SP_64 : Mips::SP,
                                         getPointerTy());
 
-  // Get the frame index of the stack frame object that points to the location
-  // of dynamically allocated area on the stack.
-  int DynAllocFI = MipsFI->getDynAllocFI();
-
-  if (MipsFI->getMaxCallFrameSize() < NextStackOffset) {
+  if (MipsFI->getMaxCallFrameSize() < NextStackOffset)
     MipsFI->setMaxCallFrameSize(NextStackOffset);
 
-    // Set the offsets relative to $sp of the $gp restore slot and dynamically
-    // allocated stack space. These offsets must be aligned to a boundary
-    // determined by the stack alignment of the ABI.
-    MFI->setObjectOffset(DynAllocFI, NextStackOffset);
-  }
-
   // With EABI is it possible to have 16 args on registers.
   SmallVector<std::pair<unsigned, SDValue>, 16> RegsToPass;
   SmallVector<SDValue, 8> MemOpChains;
diff --git a/lib/Target/Mips/MipsISelLowering.h b/lib/Target/Mips/MipsISelLowering.h
index edab03cdd8..95ea8fa885 100644
--- a/lib/Target/Mips/MipsISelLowering.h
+++ b/lib/Target/Mips/MipsISelLowering.h
@@ -132,7 +132,6 @@ namespace llvm {
     // Lower Operand specifics
     SDValue LowerBRCOND(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerConstantPool(SDValue Op, SelectionDAG &DAG) const;
-    SDValue LowerDYNAMIC_STACKALLOC(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerGlobalAddress(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerBlockAddress(SDValue Op, SelectionDAG &DAG) const;
     SDValue LowerGlobalTLSAddress(SDValue Op, SelectionDAG &DAG) const;
diff --git a/lib/Target/Mips/MipsMachineFunction.h b/lib/Target/Mips/MipsMachineFunction.h
index 9f1c85de1c..df3c4c0de0 100644
--- a/lib/Target/Mips/MipsMachineFunction.h
+++ b/lib/Target/Mips/MipsMachineFunction.h
@@ -48,7 +48,6 @@ class MipsFunctionInfo : public MachineFunctionInfo {
   // OutArgFIRange: Range of indices of all frame objects created during call to
   //                LowerCall except for the frame object for restoring $gp.
   std::pair<int, int> InArgFIRange, OutArgFIRange;
-  mutable int DynAllocFI; // Frame index of dynamically allocated stack area.
   unsigned MaxCallFrameSize;
 
   bool EmitNOAT;
@@ -57,8 +56,7 @@ public:
   MipsFunctionInfo(MachineFunction& MF)
   : MF(MF), SRetReturnReg(0), GlobalBaseReg(0),
     VarArgsFrameIndex(0), InArgFIRange(std::make_pair(-1, 0)),
-    OutArgFIRange(std::make_pair(-1, 0)), DynAllocFI(0),
-    MaxCallFrameSize(0), EmitNOAT(false)
+    OutArgFIRange(std::make_pair(-1, 0)), MaxCallFrameSize(0), EmitNOAT(false)
   {}
 
   bool isInArgFI(int FI) const {
@@ -76,16 +74,6 @@ public:
     OutArgFIRange.second = LastFI;
   }
 
-  // The first call to this function creates a frame object for dynamically
-  // allocated stack area.
-  int getDynAllocFI() const {
-    if (!DynAllocFI)
-      DynAllocFI = MF.getFrameInfo()->CreateFixedObject(4, 0, true);
-
-    return DynAllocFI;
-  }
-  bool isDynAllocFI(int FI) const { return DynAllocFI && DynAllocFI == FI; }
-
   unsigned getSRetReturnReg() const { return SRetReturnReg; }
   void setSRetReturnReg(unsigned Reg) { SRetReturnReg = Reg; }
 
diff --git a/lib/Target/Mips/MipsRegisterInfo.cpp b/lib/Target/Mips/MipsRegisterInfo.cpp
index 6bd3b78321..6a76e63413 100644
--- a/lib/Target/Mips/MipsRegisterInfo.cpp
+++ b/lib/Target/Mips/MipsRegisterInfo.cpp
@@ -199,7 +199,7 @@ eliminateFrameIndex(MachineBasicBlock::iterator II, int SPAdj,
   // getFrameRegister() returns.
   unsigned FrameReg;
 
-  if (MipsFI->isOutArgFI(FrameIndex) || MipsFI->isDynAllocFI(FrameIndex) ||
+  if (MipsFI->isOutArgFI(FrameIndex) ||
       (FrameIndex >= MinCSFI && FrameIndex <= MaxCSFI))
     FrameReg = Subtarget.isABI_N64() ? Mips::SP_64 : Mips::SP;
   else
@@ -214,7 +214,7 @@ eliminateFrameIndex(MachineBasicBlock::iterator II, int SPAdj,
   //   incoming argument, callee-saved register location or local variable.
   int64_t Offset;
 
-  if (MipsFI->isOutArgFI(FrameIndex) || MipsFI->isDynAllocFI(FrameIndex))
+  if (MipsFI->isOutArgFI(FrameIndex))
     Offset = spOffset;
   else
     Offset = spOffset + (int64_t)stackSize;