[mips] Implement eliminateCallFramePseudoInstr() in MipsFrameLowering. NFC.

[vkalintiris]

Summary

Avoid duplicate code in Mips16FrameLowering and MipsSEFrameLowering by
providing an implementation of the eliminateCallFramePseudoInstr()
function from their base class.

Depends on D8640.

[echristo]

Random drive by comment. The rest LGTM.

-eric

lib/Target/Mips/MipsFrameLowering.cpp

139

Should probably get the ABI off of the TargetMachine. I'd like to (or someone should) remove the subtarget ones at some point and migrate everything to using TM for them.

[dsanders]

Well spotted. LGTM

lib/Target/Mips/MipsFrameLowering.cpp

139

MipsSubtarget::isABI_N64() is just shorthand for TM.getABI().IsN64() at the moment. It's not that much shorter anymore so I agree we should move to using TM.getABI().IsN64() directly.

We should also rename STI to Subtarget here if the above change doesn't eliminate all the uses.. STI is normally the subtarget flags and not a MipsSubtarget object.

lib/Target/Mips/Mips16FrameLowering.h

 public:
   explicit Mips16FrameLowering(const MipsSubtarget &STI);
 
   /// emitProlog/emitEpilog - These methods insert prolog and epilog code into
   /// the function.
   void emitPrologue(MachineFunction &MF) const override;
   void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
 
-  void eliminateCallFramePseudoInstr(MachineFunction &MF,
-                                  MachineBasicBlock &MBB,
-                                  MachineBasicBlock::iterator I) const override;
-
   bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
                                  MachineBasicBlock::iterator MI,
                                  const std::vector<CalleeSavedInfo> &CSI,
                                  const TargetRegisterInfo *TRI) const override;
 
   bool restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
                                   MachineBasicBlock::iterator MI,
                                   const std::vector<CalleeSavedInfo> &CSI,

lib/Target/Mips/Mips16FrameLowering.cpp

bool Mips16FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
   // with the restore instruction during emitEpilogue.
   // We need to override this virtual function, otherwise llvm will try and
   // restore the registers on it's on from the stack.
   //
 
   return true;
 }
 
-// Eliminate ADJCALLSTACKDOWN, ADJCALLSTACKUP pseudo instructions
-void Mips16FrameLowering::
-eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
-                              MachineBasicBlock::iterator I) const {
-  if (!hasReservedCallFrame(MF)) {
-    int64_t Amount = I->getOperand(0).getImm();
-    if (Amount) {
-      if (I->getOpcode() == Mips::ADJCALLSTACKDOWN)
-        Amount = -Amount;
-
-      STI.getInstrInfo()->adjustStackPtr(Mips::SP, Amount, MBB, I);
-    }
-  }
-
-  MBB.erase(I);
-}
-
 bool
 Mips16FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
   const MachineFrameInfo *MFI = MF.getFrameInfo();
   // Reserve call frame if the size of the maximum call frame fits into 15-bit
   // immediate field and there are no variable sized objects on the stack.
   return isInt<15>(MFI->getMaxCallFrameSize()) && !MFI->hasVarSizedObjects();
 }
 

lib/Target/Mips/MipsFrameLowering.h

 public:
   explicit MipsFrameLowering(const MipsSubtarget &sti, unsigned Alignment)
     : TargetFrameLowering(StackGrowsDown, Alignment, 0, Alignment), STI(sti) {}
 
   static const MipsFrameLowering *create(const MipsSubtarget &ST);
 
   bool hasFP(const MachineFunction &MF) const override;
 
+  void
+  eliminateCallFramePseudoInstr(MachineFunction &MF,
+                                MachineBasicBlock &MBB,
+                                MachineBasicBlock::iterator I) const override;
+
 protected:
   uint64_t estimateStackSize(const MachineFunction &MF) const;
 };
 
 /// Create MipsFrameLowering objects.
 const MipsFrameLowering *createMips16FrameLowering(const MipsSubtarget &ST);
 const MipsFrameLowering *createMipsSEFrameLowering(const MipsSubtarget &ST);
 
 } // End llvm namespace
 
 #endif

lib/Target/Mips/MipsFrameLowering.cpp

uint64_t MipsFrameLowering::estimateStackSize(const MachineFunction &MF) const {
 
   // Call frame.
   if (MFI->adjustsStack() && hasReservedCallFrame(MF))
     Offset = RoundUpToAlignment(Offset + MFI->getMaxCallFrameSize(),
                                 std::max(MaxAlign, getStackAlignment()));
 
   return RoundUpToAlignment(Offset, getStackAlignment());
 }
+
+// Eliminate ADJCALLSTACKDOWN, ADJCALLSTACKUP pseudo instructions
+void MipsFrameLowering::
+eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
+                              MachineBasicBlock::iterator I) const {
+  unsigned SP = STI.isABI_N64() ? Mips::SP_64 : Mips::SP;
+
+  if (!hasReservedCallFrame(MF)) {
+    int64_t Amount = I->getOperand(0).getImm();
+    if (Amount) {
+      if (I->getOpcode() == Mips::ADJCALLSTACKDOWN)
+        Amount = -Amount;
+
+      STI.getInstrInfo()->adjustStackPtr(SP, Amount, MBB, I);
+    }
+  }
+
+  MBB.erase(I);
+}

lib/Target/Mips/MipsSEFrameLowering.h

 public:
   explicit MipsSEFrameLowering(const MipsSubtarget &STI);
 
   /// emitProlog/emitEpilog - These methods insert prolog and epilog code into
   /// the function.
   void emitPrologue(MachineFunction &MF) const override;
   void emitEpilogue(MachineFunction &MF, MachineBasicBlock &MBB) const override;
 
-  void eliminateCallFramePseudoInstr(MachineFunction &MF,
-                                  MachineBasicBlock &MBB,
-                                  MachineBasicBlock::iterator I) const override;
-
   bool spillCalleeSavedRegisters(MachineBasicBlock &MBB,
                                  MachineBasicBlock::iterator MI,
                                  const std::vector<CalleeSavedInfo> &CSI,
                                  const TargetRegisterInfo *TRI) const override;
 
   bool hasReservedCallFrame(const MachineFunction &MF) const override;
 
   void processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
                                             RegScavenger *RS) const override;
   unsigned ehDataReg(unsigned I) const;
 };
 
 } // End llvm namespace
 
 #endif

lib/Target/Mips/MipsSEFrameLowering.cpp

MipsSEFrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
   // Reserve call frame if the size of the maximum call frame fits into 16-bit
   // immediate field and there are no variable sized objects on the stack.
   // Make sure the second register scavenger spill slot can be accessed with one
   // instruction.
   return isInt<16>(MFI->getMaxCallFrameSize() + getStackAlignment()) &&
     !MFI->hasVarSizedObjects();
 }
 
-// Eliminate ADJCALLSTACKDOWN, ADJCALLSTACKUP pseudo instructions
-void MipsSEFrameLowering::
-eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
-                              MachineBasicBlock::iterator I) const {
-  if (!hasReservedCallFrame(MF)) {
-    int64_t Amount = I->getOperand(0).getImm();
-    if (Amount) {
-      if (I->getOpcode() == Mips::ADJCALLSTACKDOWN)
-        Amount = -Amount;
-
-      unsigned SP = STI.isABI_N64() ? Mips::SP_64 : Mips::SP;
-      STI.getInstrInfo()->adjustStackPtr(SP, Amount, MBB, I);
-    }
-  }
-
-  MBB.erase(I);
-}
-
 void MipsSEFrameLowering::
 processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
                                      RegScavenger *RS) const {
   MachineRegisterInfo &MRI = MF.getRegInfo();
   MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
   unsigned FP = STI.isABI_N64() ? Mips::FP_64 : Mips::FP;
 
   // Mark $fp as used if function has dedicated frame pointer.