lib/Target/MSP430/MSP430InstrInfo.cpp

   1 //===-- MSP430InstrInfo.cpp - MSP430 Instruction 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 TargetInstrInfo class.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "MSP430InstrInfo.h"
  14 #include "MSP430.h"
  15 #include "MSP430MachineFunctionInfo.h"
  16 #include "MSP430TargetMachine.h"
  17 #include "llvm/CodeGen/MachineFrameInfo.h"
  18 #include "llvm/CodeGen/MachineInstrBuilder.h"
  19 #include "llvm/CodeGen/MachineRegisterInfo.h"
  20 #include "llvm/IR/Function.h"
  21 #include "llvm/Support/ErrorHandling.h"
  22 #include "llvm/Support/TargetRegistry.h"
  23
  24 using namespace llvm;
  25
  26 #define GET_INSTRINFO_CTOR_DTOR
  27 #include "MSP430GenInstrInfo.inc"
  28
  29 // Pin the vtable to this file.
  30 void MSP430InstrInfo::anchor() {}
  31
  32 MSP430InstrInfo::MSP430InstrInfo(MSP430Subtarget &STI)
  33   : MSP430GenInstrInfo(MSP430::ADJCALLSTACKDOWN, MSP430::ADJCALLSTACKUP),
  34     RI() {}
  35
  36 void MSP430InstrInfo::storeRegToStackSlot(MachineBasicBlock &MBB,
  37                                           MachineBasicBlock::iterator MI,
  38                                     unsigned SrcReg, bool isKill, int FrameIdx,
  39                                           const TargetRegisterClass *RC,
  40                                           const TargetRegisterInfo *TRI) const {
  41   DebugLoc DL;
  42   if (MI != MBB.end()) DL = MI->getDebugLoc();
  43   MachineFunction &MF = *MBB.getParent();
  44   MachineFrameInfo &MFI = MF.getFrameInfo();
  45
  46   MachineMemOperand *MMO = MF.getMachineMemOperand(
  47       MachinePointerInfo::getFixedStack(MF, FrameIdx),
  48       MachineMemOperand::MOStore, MFI.getObjectSize(FrameIdx),
  49       MFI.getObjectAlignment(FrameIdx));
  50
  51   if (RC == &MSP430::GR16RegClass)
  52     BuildMI(MBB, MI, DL, get(MSP430::MOV16mr))
  53       .addFrameIndex(FrameIdx).addImm(0)
  54       .addReg(SrcReg, getKillRegState(isKill)).addMemOperand(MMO);
  55   else if (RC == &MSP430::GR8RegClass)
  56     BuildMI(MBB, MI, DL, get(MSP430::MOV8mr))
  57       .addFrameIndex(FrameIdx).addImm(0)
  58       .addReg(SrcReg, getKillRegState(isKill)).addMemOperand(MMO);
  59   else
  60     llvm_unreachable("Cannot store this register to stack slot!");
  61 }
  62
  63 void MSP430InstrInfo::loadRegFromStackSlot(MachineBasicBlock &MBB,
  64                                            MachineBasicBlock::iterator MI,
  65                                            unsigned DestReg, int FrameIdx,
  66                                            const TargetRegisterClass *RC,
  67                                            const TargetRegisterInfo *TRI) const{
  68   DebugLoc DL;
  69   if (MI != MBB.end()) DL = MI->getDebugLoc();
  70   MachineFunction &MF = *MBB.getParent();
  71   MachineFrameInfo &MFI = MF.getFrameInfo();
  72
  73   MachineMemOperand *MMO = MF.getMachineMemOperand(
  74       MachinePointerInfo::getFixedStack(MF, FrameIdx),
  75       MachineMemOperand::MOLoad, MFI.getObjectSize(FrameIdx),
  76       MFI.getObjectAlignment(FrameIdx));
  77
  78   if (RC == &MSP430::GR16RegClass)
  79     BuildMI(MBB, MI, DL, get(MSP430::MOV16rm))
  80       .addReg(DestReg, getDefRegState(true)).addFrameIndex(FrameIdx)
  81       .addImm(0).addMemOperand(MMO);
  82   else if (RC == &MSP430::GR8RegClass)
  83     BuildMI(MBB, MI, DL, get(MSP430::MOV8rm))
  84       .addReg(DestReg, getDefRegState(true)).addFrameIndex(FrameIdx)
  85       .addImm(0).addMemOperand(MMO);
  86   else
  87     llvm_unreachable("Cannot store this register to stack slot!");
  88 }
  89
  90 void MSP430InstrInfo::copyPhysReg(MachineBasicBlock &MBB,
  91                                   MachineBasicBlock::iterator I,
  92                                   const DebugLoc &DL, unsigned DestReg,
  93                                   unsigned SrcReg, bool KillSrc) const {
  94   unsigned Opc;
  95   if (MSP430::GR16RegClass.contains(DestReg, SrcReg))
  96     Opc = MSP430::MOV16rr;
  97   else if (MSP430::GR8RegClass.contains(DestReg, SrcReg))
  98     Opc = MSP430::MOV8rr;
  99   else
 100     llvm_unreachable("Impossible reg-to-reg copy");
 101
 102   BuildMI(MBB, I, DL, get(Opc), DestReg)
 103     .addReg(SrcReg, getKillRegState(KillSrc));
 104 }
 105
 106 unsigned MSP430InstrInfo::removeBranch(MachineBasicBlock &MBB,
 107                                        int *BytesRemoved) const {
 108   assert(!BytesRemoved && "code size not handled");
 109
 110   MachineBasicBlock::iterator I = MBB.end();
 111   unsigned Count = 0;
 112
 113   while (I != MBB.begin()) {
 114     --I;
 115     if (I->isDebugInstr())
 116       continue;
 117     if (I->getOpcode() != MSP430::JMP &&
 118         I->getOpcode() != MSP430::JCC &&
 119         I->getOpcode() != MSP430::Br &&
 120         I->getOpcode() != MSP430::Bm)
 121       break;
 122     // Remove the branch.
 123     I->eraseFromParent();
 124     I = MBB.end();
 125     ++Count;
 126   }
 127
 128   return Count;
 129 }
 130
 131 bool MSP430InstrInfo::
 132 reverseBranchCondition(SmallVectorImpl<MachineOperand> &Cond) const {
 133   assert(Cond.size() == 1 && "Invalid Xbranch condition!");
 134
 135   MSP430CC::CondCodes CC = static_cast<MSP430CC::CondCodes>(Cond[0].getImm());
 136
 137   switch (CC) {
 138   default: llvm_unreachable("Invalid branch condition!");
 139   case MSP430CC::COND_E:
 140     CC = MSP430CC::COND_NE;
 141     break;
 142   case MSP430CC::COND_NE:
 143     CC = MSP430CC::COND_E;
 144     break;
 145   case MSP430CC::COND_L:
 146     CC = MSP430CC::COND_GE;
 147     break;
 148   case MSP430CC::COND_GE:
 149     CC = MSP430CC::COND_L;
 150     break;
 151   case MSP430CC::COND_HS:
 152     CC = MSP430CC::COND_LO;
 153     break;
 154   case MSP430CC::COND_LO:
 155     CC = MSP430CC::COND_HS;
 156     break;
 157   }
 158
 159   Cond[0].setImm(CC);
 160   return false;
 161 }
 162
 163 bool MSP430InstrInfo::isUnpredicatedTerminator(const MachineInstr &MI) const {
 164   if (!MI.isTerminator())
 165     return false;
 166
 167   // Conditional branch is a special case.
 168   if (MI.isBranch() && !MI.isBarrier())
 169     return true;
 170   if (!MI.isPredicable())
 171     return true;
 172   return !isPredicated(MI);
 173 }
 174
 175 bool MSP430InstrInfo::analyzeBranch(MachineBasicBlock &MBB,
 176                                     MachineBasicBlock *&TBB,
 177                                     MachineBasicBlock *&FBB,
 178                                     SmallVectorImpl<MachineOperand> &Cond,
 179                                     bool AllowModify) const {
 180   // Start from the bottom of the block and work up, examining the
 181   // terminator instructions.
 182   MachineBasicBlock::iterator I = MBB.end();
 183   while (I != MBB.begin()) {
 184     --I;
 185     if (I->isDebugInstr())
 186       continue;
 187
 188     // Working from the bottom, when we see a non-terminator
 189     // instruction, we're done.
 190     if (!isUnpredicatedTerminator(*I))
 191       break;
 192
 193     // A terminator that isn't a branch can't easily be handled
 194     // by this analysis.
 195     if (!I->isBranch())
 196       return true;
 197
 198     // Cannot handle indirect branches.
 199     if (I->getOpcode() == MSP430::Br ||
 200         I->getOpcode() == MSP430::Bm)
 201       return true;
 202
 203     // Handle unconditional branches.
 204     if (I->getOpcode() == MSP430::JMP) {
 205       if (!AllowModify) {
 206         TBB = I->getOperand(0).getMBB();
 207         continue;
 208       }
 209
 210       // If the block has any instructions after a JMP, delete them.
 211       while (std::next(I) != MBB.end())
 212         std::next(I)->eraseFromParent();
 213       Cond.clear();
 214       FBB = nullptr;
 215
 216       // Delete the JMP if it's equivalent to a fall-through.
 217       if (MBB.isLayoutSuccessor(I->getOperand(0).getMBB())) {
 218         TBB = nullptr;
 219         I->eraseFromParent();
 220         I = MBB.end();
 221         continue;
 222       }
 223
 224       // TBB is used to indicate the unconditinal destination.
 225       TBB = I->getOperand(0).getMBB();
 226       continue;
 227     }
 228
 229     // Handle conditional branches.
 230     assert(I->getOpcode() == MSP430::JCC && "Invalid conditional branch");
 231     MSP430CC::CondCodes BranchCode =
 232       static_cast<MSP430CC::CondCodes>(I->getOperand(1).getImm());
 233     if (BranchCode == MSP430CC::COND_INVALID)
 234       return true;  // Can't handle weird stuff.
 235
 236     // Working from the bottom, handle the first conditional branch.
 237     if (Cond.empty()) {
 238       FBB = TBB;
 239       TBB = I->getOperand(0).getMBB();
 240       Cond.push_back(MachineOperand::CreateImm(BranchCode));
 241       continue;
 242     }
 243
 244     // Handle subsequent conditional branches. Only handle the case where all
 245     // conditional branches branch to the same destination.
 246     assert(Cond.size() == 1);
 247     assert(TBB);
 248
 249     // Only handle the case where all conditional branches branch to
 250     // the same destination.
 251     if (TBB != I->getOperand(0).getMBB())
 252       return true;
 253
 254     MSP430CC::CondCodes OldBranchCode = (MSP430CC::CondCodes)Cond[0].getImm();
 255     // If the conditions are the same, we can leave them alone.
 256     if (OldBranchCode == BranchCode)
 257       continue;
 258
 259     return true;
 260   }
 261
 262   return false;
 263 }
 264
 265 unsigned MSP430InstrInfo::insertBranch(MachineBasicBlock &MBB,
 266                                        MachineBasicBlock *TBB,
 267                                        MachineBasicBlock *FBB,
 268                                        ArrayRef<MachineOperand> Cond,
 269                                        const DebugLoc &DL,
 270                                        int *BytesAdded) const {
 271   // Shouldn't be a fall through.
 272   assert(TBB && "insertBranch must not be told to insert a fallthrough");
 273   assert((Cond.size() == 1 || Cond.size() == 0) &&
 274          "MSP430 branch conditions have one component!");
 275   assert(!BytesAdded && "code size not handled");
 276
 277   if (Cond.empty()) {
 278     // Unconditional branch?
 279     assert(!FBB && "Unconditional branch with multiple successors!");
 280     BuildMI(&MBB, DL, get(MSP430::JMP)).addMBB(TBB);
 281     return 1;
 282   }
 283
 284   // Conditional branch.
 285   unsigned Count = 0;
 286   BuildMI(&MBB, DL, get(MSP430::JCC)).addMBB(TBB).addImm(Cond[0].getImm());
 287   ++Count;
 288
 289   if (FBB) {
 290     // Two-way Conditional branch. Insert the second branch.
 291     BuildMI(&MBB, DL, get(MSP430::JMP)).addMBB(FBB);
 292     ++Count;
 293   }
 294   return Count;
 295 }
 296
 297 /// GetInstSize - Return the number of bytes of code the specified
 298 /// instruction may be.  This returns the maximum number of bytes.
 299 ///
 300 unsigned MSP430InstrInfo::getInstSizeInBytes(const MachineInstr &MI) const {
 301   const MCInstrDesc &Desc = MI.getDesc();
 302
 303   switch (Desc.getOpcode()) {
 304   case TargetOpcode::CFI_INSTRUCTION:
 305   case TargetOpcode::EH_LABEL:
 306   case TargetOpcode::IMPLICIT_DEF:
 307   case TargetOpcode::KILL:
 308   case TargetOpcode::DBG_VALUE:
 309     return 0;
 310   case TargetOpcode::INLINEASM:
 311   case TargetOpcode::INLINEASM_BR: {
 312     const MachineFunction *MF = MI.getParent()->getParent();
 313     const TargetInstrInfo &TII = *MF->getSubtarget().getInstrInfo();
 314     return TII.getInlineAsmLength(MI.getOperand(0).getSymbolName(),
 315                                   *MF->getTarget().getMCAsmInfo());
 316   }
 317   }
 318
 319   return Desc.getSize();
 320 }