lib/Target/Mips/MipsSERegisterInfo.cpp

   1 //===-- MipsSERegisterInfo.cpp - MIPS32/64 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 MIPS32/64 implementation of the TargetRegisterInfo
  10 // class.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "MipsSERegisterInfo.h"
  15 #include "Mips.h"
  16 #include "MipsMachineFunction.h"
  17 #include "MipsSEInstrInfo.h"
  18 #include "MipsSubtarget.h"
  19 #include "MipsTargetMachine.h"
  20 #include "llvm/ADT/STLExtras.h"
  21 #include "llvm/CodeGen/MachineFrameInfo.h"
  22 #include "llvm/CodeGen/MachineFunction.h"
  23 #include "llvm/CodeGen/MachineInstrBuilder.h"
  24 #include "llvm/CodeGen/MachineRegisterInfo.h"
  25 #include "llvm/CodeGen/TargetFrameLowering.h"
  26 #include "llvm/CodeGen/TargetInstrInfo.h"
  27 #include "llvm/IR/Constants.h"
  28 #include "llvm/IR/DebugInfo.h"
  29 #include "llvm/IR/Function.h"
  30 #include "llvm/IR/Type.h"
  31 #include "llvm/Support/Debug.h"
  32 #include "llvm/Support/ErrorHandling.h"
  33 #include "llvm/Support/raw_ostream.h"
  34 #include "llvm/Target/TargetMachine.h"
  35 #include "llvm/Target/TargetOptions.h"
  36
  37 using namespace llvm;
  38
  39 #define DEBUG_TYPE "mips-reg-info"
  40
  41 MipsSERegisterInfo::MipsSERegisterInfo() : MipsRegisterInfo() {}
  42
  43 bool MipsSERegisterInfo::
  44 requiresRegisterScavenging(const MachineFunction &MF) const {
  45   return true;
  46 }
  47
  48 bool MipsSERegisterInfo::
  49 requiresFrameIndexScavenging(const MachineFunction &MF) const {
  50   return true;
  51 }
  52
  53 const TargetRegisterClass *
  54 MipsSERegisterInfo::intRegClass(unsigned Size) const {
  55   if (Size == 4)
  56     return &Mips::GPR32RegClass;
  57
  58   assert(Size == 8);
  59   return &Mips::GPR64RegClass;
  60 }
  61
  62 /// Get the size of the offset supported by the given load/store/inline asm.
  63 /// The result includes the effects of any scale factors applied to the
  64 /// instruction immediate.
  65 static inline unsigned getLoadStoreOffsetSizeInBits(const unsigned Opcode,
  66                                                     MachineOperand MO) {
  67   switch (Opcode) {
  68   case Mips::LD_B:
  69   case Mips::ST_B:
  70     return 10;
  71   case Mips::LD_H:
  72   case Mips::ST_H:
  73     return 10 + 1 /* scale factor */;
  74   case Mips::LD_W:
  75   case Mips::ST_W:
  76     return 10 + 2 /* scale factor */;
  77   case Mips::LD_D:
  78   case Mips::ST_D:
  79     return 10 + 3 /* scale factor */;
  80   case Mips::LL:
  81   case Mips::LL64:
  82   case Mips::LLD:
  83   case Mips::LLE:
  84   case Mips::SC:
  85   case Mips::SC64:
  86   case Mips::SCD:
  87   case Mips::SCE:
  88     return 16;
  89   case Mips::LLE_MM:
  90   case Mips::LL_MM:
  91   case Mips::SCE_MM:
  92   case Mips::SC_MM:
  93     return 12;
  94   case Mips::LL64_R6:
  95   case Mips::LL_R6:
  96   case Mips::LLD_R6:
  97   case Mips::SC64_R6:
  98   case Mips::SCD_R6:
  99   case Mips::SC_R6:
 100   case Mips::LL_MMR6:
 101   case Mips::SC_MMR6:
 102     return 9;
 103   case Mips::INLINEASM: {
 104     unsigned ConstraintID = InlineAsm::getMemoryConstraintID(MO.getImm());
 105     switch (ConstraintID) {
 106     case InlineAsm::Constraint_ZC: {
 107       const MipsSubtarget &Subtarget = MO.getParent()
 108                                            ->getParent()
 109                                            ->getParent()
 110                                            ->getSubtarget<MipsSubtarget>();
 111       if (Subtarget.inMicroMipsMode())
 112         return 12;
 113
 114       if (Subtarget.hasMips32r6())
 115         return 9;
 116
 117       return 16;
 118     }
 119     default:
 120       return 16;
 121     }
 122   }
 123   default:
 124     return 16;
 125   }
 126 }
 127
 128 /// Get the scale factor applied to the immediate in the given load/store.
 129 static inline unsigned getLoadStoreOffsetAlign(const unsigned Opcode) {
 130   switch (Opcode) {
 131   case Mips::LD_H:
 132   case Mips::ST_H:
 133     return 2;
 134   case Mips::LD_W:
 135   case Mips::ST_W:
 136     return 4;
 137   case Mips::LD_D:
 138   case Mips::ST_D:
 139     return 8;
 140   default:
 141     return 1;
 142   }
 143 }
 144
 145 void MipsSERegisterInfo::eliminateFI(MachineBasicBlock::iterator II,
 146                                      unsigned OpNo, int FrameIndex,
 147                                      uint64_t StackSize,
 148                                      int64_t SPOffset) const {
 149   MachineInstr &MI = *II;
 150   MachineFunction &MF = *MI.getParent()->getParent();
 151   MachineFrameInfo &MFI = MF.getFrameInfo();
 152   MipsFunctionInfo *MipsFI = MF.getInfo<MipsFunctionInfo>();
 153
 154   MipsABIInfo ABI =
 155       static_cast<const MipsTargetMachine &>(MF.getTarget()).getABI();
 156   const MipsRegisterInfo *RegInfo =
 157     static_cast<const MipsRegisterInfo *>(MF.getSubtarget().getRegisterInfo());
 158
 159   const std::vector<CalleeSavedInfo> &CSI = MFI.getCalleeSavedInfo();
 160   int MinCSFI = 0;
 161   int MaxCSFI = -1;
 162
 163   if (CSI.size()) {
 164     MinCSFI = CSI[0].getFrameIdx();
 165     MaxCSFI = CSI[CSI.size() - 1].getFrameIdx();
 166   }
 167
 168   bool EhDataRegFI = MipsFI->isEhDataRegFI(FrameIndex);
 169   bool IsISRRegFI = MipsFI->isISRRegFI(FrameIndex);
 170   // The following stack frame objects are always referenced relative to $sp:
 171   //  1. Outgoing arguments.
 172   //  2. Pointer to dynamically allocated stack space.
 173   //  3. Locations for callee-saved registers.
 174   //  4. Locations for eh data registers.
 175   //  5. Locations for ISR saved Coprocessor 0 registers 12 & 14.
 176   // Everything else is referenced relative to whatever register
 177   // getFrameRegister() returns.
 178   unsigned FrameReg;
 179
 180   if ((FrameIndex >= MinCSFI && FrameIndex <= MaxCSFI) || EhDataRegFI ||
 181       IsISRRegFI)
 182     FrameReg = ABI.GetStackPtr();
 183   else if (RegInfo->needsStackRealignment(MF)) {
 184     if (MFI.hasVarSizedObjects() && !MFI.isFixedObjectIndex(FrameIndex))
 185       FrameReg = ABI.GetBasePtr();
 186     else if (MFI.isFixedObjectIndex(FrameIndex))
 187       FrameReg = getFrameRegister(MF);
 188     else
 189       FrameReg = ABI.GetStackPtr();
 190   } else
 191     FrameReg = getFrameRegister(MF);
 192
 193   // Calculate final offset.
 194   // - There is no need to change the offset if the frame object is one of the
 195   //   following: an outgoing argument, pointer to a dynamically allocated
 196   //   stack space or a $gp restore location,
 197   // - If the frame object is any of the following, its offset must be adjusted
 198   //   by adding the size of the stack:
 199   //   incoming argument, callee-saved register location or local variable.
 200   bool IsKill = false;
 201   int64_t Offset;
 202
 203   Offset = SPOffset + (int64_t)StackSize;
 204   Offset += MI.getOperand(OpNo + 1).getImm();
 205
 206   LLVM_DEBUG(errs() << "Offset     : " << Offset << "\n"
 207                     << "<--------->\n");
 208
 209   if (!MI.isDebugValue()) {
 210     // Make sure Offset fits within the field available.
 211     // For MSA instructions, this is a 10-bit signed immediate (scaled by
 212     // element size), otherwise it is a 16-bit signed immediate.
 213     unsigned OffsetBitSize =
 214         getLoadStoreOffsetSizeInBits(MI.getOpcode(), MI.getOperand(OpNo - 1));
 215     unsigned OffsetAlign = getLoadStoreOffsetAlign(MI.getOpcode());
 216
 217     if (OffsetBitSize < 16 && isInt<16>(Offset) &&
 218         (!isIntN(OffsetBitSize, Offset) ||
 219          OffsetToAlignment(Offset, OffsetAlign) != 0)) {
 220       // If we have an offset that needs to fit into a signed n-bit immediate
 221       // (where n < 16) and doesn't, but does fit into 16-bits then use an ADDiu
 222       MachineBasicBlock &MBB = *MI.getParent();
 223       DebugLoc DL = II->getDebugLoc();
 224       const TargetRegisterClass *PtrRC =
 225           ABI.ArePtrs64bit() ? &Mips::GPR64RegClass : &Mips::GPR32RegClass;
 226       MachineRegisterInfo &RegInfo = MBB.getParent()->getRegInfo();
 227       unsigned Reg = RegInfo.createVirtualRegister(PtrRC);
 228       const MipsSEInstrInfo &TII =
 229           *static_cast<const MipsSEInstrInfo *>(
 230               MBB.getParent()->getSubtarget().getInstrInfo());
 231       BuildMI(MBB, II, DL, TII.get(ABI.GetPtrAddiuOp()), Reg)
 232           .addReg(FrameReg)
 233           .addImm(Offset);
 234
 235       FrameReg = Reg;
 236       Offset = 0;
 237       IsKill = true;
 238     } else if (!isInt<16>(Offset)) {
 239       // Otherwise split the offset into 16-bit pieces and add it in multiple
 240       // instructions.
 241       MachineBasicBlock &MBB = *MI.getParent();
 242       DebugLoc DL = II->getDebugLoc();
 243       unsigned NewImm = 0;
 244       const MipsSEInstrInfo &TII =
 245           *static_cast<const MipsSEInstrInfo *>(
 246               MBB.getParent()->getSubtarget().getInstrInfo());
 247       unsigned Reg = TII.loadImmediate(Offset, MBB, II, DL,
 248                                        OffsetBitSize == 16 ? &NewImm : nullptr);
 249       BuildMI(MBB, II, DL, TII.get(ABI.GetPtrAdduOp()), Reg).addReg(FrameReg)
 250         .addReg(Reg, RegState::Kill);
 251
 252       FrameReg = Reg;
 253       Offset = SignExtend64<16>(NewImm);
 254       IsKill = true;
 255     }
 256   }
 257
 258   MI.getOperand(OpNo).ChangeToRegister(FrameReg, false, false, IsKill);
 259   MI.getOperand(OpNo + 1).ChangeToImmediate(Offset);
 260 }