llvm/lib/Target/MSP430/MSP430RegisterInfo.cpp

   1 //===-- MSP430RegisterInfo.cpp - MSP430 Register Information --------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file contains the MSP430 implementation of the TargetRegisterInfo class.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "MSP430RegisterInfo.h"
  14 #include "MSP430.h"
  15 #include "MSP430MachineFunctionInfo.h"
  16 #include "MSP430TargetMachine.h"
  17 #include "llvm/ADT/BitVector.h"
  18 #include "llvm/CodeGen/MachineFrameInfo.h"
  19 #include "llvm/CodeGen/MachineFunction.h"
  20 #include "llvm/CodeGen/MachineInstrBuilder.h"
  21 #include "llvm/IR/Function.h"
  22 #include "llvm/Support/ErrorHandling.h"
  23 #include "llvm/Target/TargetMachine.h"
  24 #include "llvm/Target/TargetOptions.h"
  25
  26 using namespace llvm;
  27
  28 #define DEBUG_TYPE "msp430-reg-info"
  29
  30 #define GET_REGINFO_TARGET_DESC
  31 #include "MSP430GenRegisterInfo.inc"
  32
  33 // FIXME: Provide proper call frame setup / destroy opcodes.
  34 MSP430RegisterInfo::MSP430RegisterInfo()
  35   : MSP430GenRegisterInfo(MSP430::PC) {}
  36
  37 const MCPhysReg*
  38 MSP430RegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
  39   const MSP430FrameLowering *TFI = getFrameLowering(*MF);
  40   const Function* F = &MF->getFunction();
  41   static const MCPhysReg CalleeSavedRegs[] = {
  42     MSP430::R4, MSP430::R5, MSP430::R6, MSP430::R7,
  43     MSP430::R8, MSP430::R9, MSP430::R10,
  44     0
  45   };
  46   static const MCPhysReg CalleeSavedRegsFP[] = {
  47     MSP430::R5, MSP430::R6, MSP430::R7,
  48     MSP430::R8, MSP430::R9, MSP430::R10,
  49     0
  50   };
  51   static const MCPhysReg CalleeSavedRegsIntr[] = {
  52     MSP430::R4,  MSP430::R5,  MSP430::R6,  MSP430::R7,
  53     MSP430::R8,  MSP430::R9,  MSP430::R10, MSP430::R11,
  54     MSP430::R12, MSP430::R13, MSP430::R14, MSP430::R15,
  55     0
  56   };
  57   static const MCPhysReg CalleeSavedRegsIntrFP[] = {
  58     MSP430::R5,  MSP430::R6,  MSP430::R7,
  59     MSP430::R8,  MSP430::R9,  MSP430::R10, MSP430::R11,
  60     MSP430::R12, MSP430::R13, MSP430::R14, MSP430::R15,
  61     0
  62   };
  63
  64   if (TFI->hasFP(*MF))
  65     return (F->getCallingConv() == CallingConv::MSP430_INTR ?
  66             CalleeSavedRegsIntrFP : CalleeSavedRegsFP);
  67   else
  68     return (F->getCallingConv() == CallingConv::MSP430_INTR ?
  69             CalleeSavedRegsIntr : CalleeSavedRegs);
  70
  71 }
  72
  73 BitVector MSP430RegisterInfo::getReservedRegs(const MachineFunction &MF) const {
  74   BitVector Reserved(getNumRegs());
  75   const MSP430FrameLowering *TFI = getFrameLowering(MF);
  76
  77   // Mark 4 special registers with subregisters as reserved.
  78   Reserved.set(MSP430::PCB);
  79   Reserved.set(MSP430::SPB);
  80   Reserved.set(MSP430::SRB);
  81   Reserved.set(MSP430::CGB);
  82   Reserved.set(MSP430::PC);
  83   Reserved.set(MSP430::SP);
  84   Reserved.set(MSP430::SR);
  85   Reserved.set(MSP430::CG);
  86
  87   // Mark frame pointer as reserved if needed.
  88   if (TFI->hasFP(MF)) {
  89     Reserved.set(MSP430::R4B);
  90     Reserved.set(MSP430::R4);
  91   }
  92
  93   return Reserved;
  94 }
  95
  96 const TargetRegisterClass *
  97 MSP430RegisterInfo::getPointerRegClass(const MachineFunction &MF, unsigned Kind)
  98                                                                          const {
  99   return &MSP430::GR16RegClass;
 100 }
 101
 102 bool
 103 MSP430RegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
 104                                         int SPAdj, unsigned FIOperandNum,
 105                                         RegScavenger *RS) const {
 106   assert(SPAdj == 0 && "Unexpected");
 107
 108   MachineInstr &MI = *II;
 109   MachineBasicBlock &MBB = *MI.getParent();
 110   MachineFunction &MF = *MBB.getParent();
 111   const MSP430FrameLowering *TFI = getFrameLowering(MF);
 112   DebugLoc dl = MI.getDebugLoc();
 113   int FrameIndex = MI.getOperand(FIOperandNum).getIndex();
 114
 115   unsigned BasePtr = (TFI->hasFP(MF) ? MSP430::R4 : MSP430::SP);
 116   int Offset = MF.getFrameInfo().getObjectOffset(FrameIndex);
 117
 118   // Skip the saved PC
 119   Offset += 2;
 120
 121   if (!TFI->hasFP(MF))
 122     Offset += MF.getFrameInfo().getStackSize();
 123   else
 124     Offset += 2; // Skip the saved FP
 125
 126   // Fold imm into offset
 127   Offset += MI.getOperand(FIOperandNum + 1).getImm();
 128
 129   if (MI.getOpcode() == MSP430::ADDframe) {
 130     // This is actually "load effective address" of the stack slot
 131     // instruction. We have only two-address instructions, thus we need to
 132     // expand it into mov + add
 133     const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
 134
 135     MI.setDesc(TII.get(MSP430::MOV16rr));
 136     MI.getOperand(FIOperandNum).ChangeToRegister(BasePtr, false);
 137
 138     // Remove the now unused Offset operand.
 139     MI.removeOperand(FIOperandNum + 1);
 140
 141     if (Offset == 0)
 142       return false;
 143
 144     // We need to materialize the offset via add instruction.
 145     Register DstReg = MI.getOperand(0).getReg();
 146     if (Offset < 0)
 147       BuildMI(MBB, std::next(II), dl, TII.get(MSP430::SUB16ri), DstReg)
 148         .addReg(DstReg).addImm(-Offset);
 149     else
 150       BuildMI(MBB, std::next(II), dl, TII.get(MSP430::ADD16ri), DstReg)
 151         .addReg(DstReg).addImm(Offset);
 152
 153     return false;
 154   }
 155
 156   MI.getOperand(FIOperandNum).ChangeToRegister(BasePtr, false);
 157   MI.getOperand(FIOperandNum + 1).ChangeToImmediate(Offset);
 158   return false;
 159 }
 160
 161 Register MSP430RegisterInfo::getFrameRegister(const MachineFunction &MF) const {
 162   const MSP430FrameLowering *TFI = getFrameLowering(MF);
 163   return TFI->hasFP(MF) ? MSP430::R4 : MSP430::SP;
 164 }