lib/Target/SystemZ/SystemZRegisterInfo.cpp

   1 //===- SystemZRegisterInfo.cpp - SystemZ Register Information -------*- C++ -*-===//
   2 //
   3 //                     The LLVM Compiler Infrastructure
   4 //
   5 // This file is distributed under the University of Illinois Open Source
   6 // License. See LICENSE.TXT for details.
   7 //
   8 //===----------------------------------------------------------------------===//
   9 //
  10 // This file contains the SystemZ implementation of the TargetRegisterInfo class.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "SystemZ.h"
  15 #include "SystemZInstrInfo.h"
  16 #include "SystemZMachineFunctionInfo.h"
  17 #include "SystemZRegisterInfo.h"
  18 #include "SystemZSubtarget.h"
  19 #include "llvm/CodeGen/MachineInstrBuilder.h"
  20 #include "llvm/CodeGen/MachineFrameInfo.h"
  21 #include "llvm/CodeGen/MachineFunction.h"
  22 #include "llvm/CodeGen/MachineRegisterInfo.h"
  23 #include "llvm/Target/TargetFrameInfo.h"
  24 #include "llvm/Target/TargetInstrInfo.h"
  25 #include "llvm/Target/TargetMachine.h"
  26 #include "llvm/Target/TargetOptions.h"
  27 #include "llvm/ADT/BitVector.h"
  28 using namespace llvm;
  29
  30 SystemZRegisterInfo::SystemZRegisterInfo(SystemZTargetMachine &tm,
  31                                          const SystemZInstrInfo &tii)
  32   : SystemZGenRegisterInfo(SystemZ::ADJCALLSTACKUP, SystemZ::ADJCALLSTACKDOWN),
  33     TM(tm), TII(tii) {
  34 }
  35
  36 const unsigned*
  37 SystemZRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
  38   static const unsigned CalleeSavedRegs[] = {
  39     SystemZ::R6D,  SystemZ::R7D,  SystemZ::R8D,  SystemZ::R9D,
  40     SystemZ::R10D, SystemZ::R11D, SystemZ::R12D, SystemZ::R13D,
  41     SystemZ::R14D, SystemZ::R15D,
  42     SystemZ::F8L,  SystemZ::F9L,  SystemZ::F10L, SystemZ::F11L,
  43     SystemZ::F12L, SystemZ::F13L, SystemZ::F14L, SystemZ::F15L,
  44     0
  45   };
  46
  47   return CalleeSavedRegs;
  48 }
  49
  50 const TargetRegisterClass* const*
  51 SystemZRegisterInfo::getCalleeSavedRegClasses(const MachineFunction *MF) const {
  52   static const TargetRegisterClass * const CalleeSavedRegClasses[] = {
  53     &SystemZ::GR64RegClass, &SystemZ::GR64RegClass,
  54     &SystemZ::GR64RegClass, &SystemZ::GR64RegClass,
  55     &SystemZ::GR64RegClass, &SystemZ::GR64RegClass,
  56     &SystemZ::GR64RegClass, &SystemZ::GR64RegClass,
  57     &SystemZ::GR64RegClass, &SystemZ::GR64RegClass,
  58     &SystemZ::FP64RegClass, &SystemZ::FP64RegClass,
  59     &SystemZ::FP64RegClass, &SystemZ::FP64RegClass,
  60     &SystemZ::FP64RegClass, &SystemZ::FP64RegClass,
  61     &SystemZ::FP64RegClass, &SystemZ::FP64RegClass, 0
  62   };
  63   return CalleeSavedRegClasses;
  64 }
  65
  66 BitVector SystemZRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
  67   BitVector Reserved(getNumRegs());
  68   if (hasFP(MF))
  69     Reserved.set(SystemZ::R11D);
  70   Reserved.set(SystemZ::R14D);
  71   Reserved.set(SystemZ::R15D);
  72   return Reserved;
  73 }
  74
  75 /// needsFP - Return true if the specified function should have a dedicated
  76 /// frame pointer register.  This is true if the function has variable sized
  77 /// allocas or if frame pointer elimination is disabled.
  78 bool SystemZRegisterInfo::hasFP(const MachineFunction &MF) const {
  79   const MachineFrameInfo *MFI = MF.getFrameInfo();
  80   return NoFramePointerElim || MFI->hasVarSizedObjects();
  81 }
  82
  83 void SystemZRegisterInfo::
  84 eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
  85                               MachineBasicBlock::iterator I) const {
  86   MBB.erase(I);
  87 }
  88
  89 int SystemZRegisterInfo::getFrameIndexOffset(MachineFunction &MF, int FI) const {
  90   const TargetFrameInfo &TFI = *MF.getTarget().getFrameInfo();
  91   MachineFrameInfo *MFI = MF.getFrameInfo();
  92   SystemZMachineFunctionInfo *SystemZMFI =
  93     MF.getInfo<SystemZMachineFunctionInfo>();
  94   int Offset = MFI->getObjectOffset(FI) + MFI->getOffsetAdjustment();
  95   uint64_t StackSize = MFI->getStackSize();
  96
  97   // Fixed objects are really located in the "previous" frame.
  98   if (FI < 0)
  99     StackSize -= SystemZMFI->getCalleeSavedFrameSize();
 100
 101   Offset += StackSize - TFI.getOffsetOfLocalArea();
 102
 103   // Skip the register save area if we generated the stack frame.
 104   if (StackSize || MFI->hasCalls())
 105     Offset -= TFI.getOffsetOfLocalArea();
 106
 107   return Offset;
 108 }
 109
 110 void SystemZRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
 111                                             int SPAdj, RegScavenger *RS) const {
 112   assert(SPAdj == 0 && "Unxpected");
 113
 114   unsigned i = 0;
 115   MachineInstr &MI = *II;
 116   MachineFunction &MF = *MI.getParent()->getParent();
 117   while (!MI.getOperand(i).isFI()) {
 118     ++i;
 119     assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
 120   }
 121
 122   int FrameIndex = MI.getOperand(i).getIndex();
 123
 124   unsigned BasePtr = (hasFP(MF) ? SystemZ::R11D : SystemZ::R15D);
 125
 126   // This must be part of a rri or ri operand memory reference.  Replace the
 127   // FrameIndex with base register with BasePtr.  Add an offset to the
 128   // displacement field.
 129   MI.getOperand(i).ChangeToRegister(BasePtr, false);
 130
 131   // Offset is a either 12-bit unsigned or 20-bit signed integer.
 132   // FIXME: handle "too long" displacements.
 133   int Offset = getFrameIndexOffset(MF, FrameIndex) + MI.getOperand(i+1).getImm();
 134
 135   // Check whether displacement is too long to fit into 12 bit zext field.
 136   MI.setDesc(TII.getMemoryInstr(MI.getOpcode(), Offset));
 137
 138   MI.getOperand(i+1).ChangeToImmediate(Offset);
 139 }
 140
 141 void
 142 SystemZRegisterInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
 143                                                        RegScavenger *RS) const {
 144   // Determine whether R15/R14 will ever be clobbered inside the function. And
 145   // if yes - mark it as 'callee' saved.
 146   MachineFrameInfo *FFI = MF.getFrameInfo();
 147   MachineRegisterInfo &MRI = MF.getRegInfo();
 148
 149   // Check whether high FPRs are ever used, if yes - we need to save R15 as
 150   // well.
 151   static const unsigned HighFPRs[] = {
 152     SystemZ::F8L,  SystemZ::F9L,  SystemZ::F10L, SystemZ::F11L,
 153     SystemZ::F12L, SystemZ::F13L, SystemZ::F14L, SystemZ::F15L,
 154     SystemZ::F8S,  SystemZ::F9S,  SystemZ::F10S, SystemZ::F11S,
 155     SystemZ::F12S, SystemZ::F13S, SystemZ::F14S, SystemZ::F15S,
 156   };
 157
 158   bool HighFPRsUsed = false;
 159   for (unsigned i = 0, e = array_lengthof(HighFPRs); i != e; ++i)
 160     HighFPRsUsed |= MRI.isPhysRegUsed(HighFPRs[i]);
 161
 162   if (FFI->hasCalls())
 163     /* FIXME: function is varargs */
 164     /* FIXME: function grabs RA */
 165     /* FIXME: function calls eh_return */
 166     MRI.setPhysRegUsed(SystemZ::R14D);
 167
 168   if (HighFPRsUsed ||
 169       FFI->hasCalls() ||
 170       FFI->getObjectIndexEnd() != 0 || // Contains automatic variables
 171       FFI->hasVarSizedObjects() // Function calls dynamic alloca's
 172       /* FIXME: function is varargs */)
 173     MRI.setPhysRegUsed(SystemZ::R15D);
 174 }
 175
 176 /// emitSPUpdate - Emit a series of instructions to increment / decrement the
 177 /// stack pointer by a constant value.
 178 static
 179 void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
 180                   int64_t NumBytes, const TargetInstrInfo &TII) {
 181   unsigned Opc; uint64_t Chunk;
 182   bool isSub = NumBytes < 0;
 183   uint64_t Offset = isSub ? -NumBytes : NumBytes;
 184
 185   if (Offset >= (1LL << 15) - 1) {
 186     Opc = SystemZ::ADD64ri32;
 187     Chunk = (1LL << 31) - 1;
 188   } else {
 189     Opc = SystemZ::ADD64ri16;
 190     Chunk = (1LL << 15) - 1;
 191   }
 192
 193   DebugLoc DL = (MBBI != MBB.end() ? MBBI->getDebugLoc() :
 194                  DebugLoc::getUnknownLoc());
 195
 196   while (Offset) {
 197     uint64_t ThisVal = (Offset > Chunk) ? Chunk : Offset;
 198     MachineInstr *MI =
 199       BuildMI(MBB, MBBI, DL, TII.get(Opc), SystemZ::R15D)
 200       .addReg(SystemZ::R15D).addImm((isSub ? -(int64_t)ThisVal : ThisVal));
 201     // The PSW implicit def is dead.
 202     MI->getOperand(3).setIsDead();
 203     Offset -= ThisVal;
 204   }
 205 }
 206
 207 void SystemZRegisterInfo::emitPrologue(MachineFunction &MF) const {
 208   MachineBasicBlock &MBB = MF.front();   // Prolog goes in entry BB
 209   const TargetFrameInfo &TFI = *MF.getTarget().getFrameInfo();
 210   MachineFrameInfo *MFI = MF.getFrameInfo();
 211   SystemZMachineFunctionInfo *SystemZMFI =
 212     MF.getInfo<SystemZMachineFunctionInfo>();
 213   MachineBasicBlock::iterator MBBI = MBB.begin();
 214   DebugLoc DL = (MBBI != MBB.end() ? MBBI->getDebugLoc() :
 215                  DebugLoc::getUnknownLoc());
 216
 217   // Get the number of bytes to allocate from the FrameInfo.
 218   // Note that area for callee-saved stuff is already allocated, thus we need to
 219   // 'undo' the stack movement.
 220   uint64_t StackSize = MFI->getStackSize();
 221   StackSize -= SystemZMFI->getCalleeSavedFrameSize();
 222
 223   uint64_t NumBytes = StackSize - TFI.getOffsetOfLocalArea();
 224
 225   // Skip the callee-saved push instructions.
 226   while (MBBI != MBB.end() &&
 227          (MBBI->getOpcode() == SystemZ::MOV64mr ||
 228           MBBI->getOpcode() == SystemZ::MOV64mrm))
 229     ++MBBI;
 230
 231   if (MBBI != MBB.end())
 232     DL = MBBI->getDebugLoc();
 233
 234   // adjust stack pointer: R15 -= numbytes
 235   if (StackSize || MFI->hasCalls()) {
 236     assert(MF.getRegInfo().isPhysRegUsed(SystemZ::R15D) &&
 237            "Invalid stack frame calculation!");
 238     emitSPUpdate(MBB, MBBI, -(int64_t)NumBytes, TII);
 239   }
 240
 241   if (hasFP(MF)) {
 242     // Update R11 with the new base value...
 243     BuildMI(MBB, MBBI, DL, TII.get(SystemZ::MOV64rr), SystemZ::R11D)
 244       .addReg(SystemZ::R15D);
 245
 246     // Mark the FramePtr as live-in in every block except the entry.
 247     for (MachineFunction::iterator I = next(MF.begin()), E = MF.end();
 248          I != E; ++I)
 249       I->addLiveIn(SystemZ::R11D);
 250
 251   }
 252 }
 253
 254 void SystemZRegisterInfo::emitEpilogue(MachineFunction &MF,
 255                                      MachineBasicBlock &MBB) const {
 256   const MachineFrameInfo *MFI = MF.getFrameInfo();
 257   const TargetFrameInfo &TFI = *MF.getTarget().getFrameInfo();
 258   MachineBasicBlock::iterator MBBI = prior(MBB.end());
 259   SystemZMachineFunctionInfo *SystemZMFI =
 260     MF.getInfo<SystemZMachineFunctionInfo>();
 261   unsigned RetOpcode = MBBI->getOpcode();
 262
 263   switch (RetOpcode) {
 264   case SystemZ::RET: break;  // These are ok
 265   default:
 266     assert(0 && "Can only insert epilog into returning blocks");
 267   }
 268
 269   // Get the number of bytes to allocate from the FrameInfo
 270   // Note that area for callee-saved stuff is already allocated, thus we need to
 271   // 'undo' the stack movement.
 272   uint64_t StackSize =
 273     MFI->getStackSize() - SystemZMFI->getCalleeSavedFrameSize();
 274   uint64_t NumBytes = StackSize - TFI.getOffsetOfLocalArea();
 275
 276   // Skip the final terminator instruction.
 277   while (MBBI != MBB.begin()) {
 278     MachineBasicBlock::iterator PI = prior(MBBI);
 279     --MBBI;
 280     if (!PI->getDesc().isTerminator())
 281       break;
 282   }
 283
 284   // During callee-saved restores emission stack frame was not yet finialized
 285   // (and thus - the stack size was unknown). Tune the offset having full stack
 286   // size in hands.
 287   if (StackSize || MFI->hasCalls()) {
 288     assert((MBBI->getOpcode() == SystemZ::MOV64rmm ||
 289             MBBI->getOpcode() == SystemZ::MOV64rm) &&
 290            "Expected to see callee-save register restore code");
 291     assert(MF.getRegInfo().isPhysRegUsed(SystemZ::R15D) &&
 292            "Invalid stack frame calculation!");
 293
 294     unsigned i = 0;
 295     MachineInstr &MI = *MBBI;
 296     while (!MI.getOperand(i).isImm()) {
 297       ++i;
 298       assert(i < MI.getNumOperands() && "Unexpected restore code!");
 299     }
 300
 301     uint64_t Offset = NumBytes + MI.getOperand(i).getImm();
 302     // If Offset does not fit into 20-bit signed displacement field we need to
 303     // emit some additional code...
 304     if (Offset > 524287) {
 305       // Fold the displacement into load instruction as much as possible.
 306       NumBytes = Offset - 524287;
 307       Offset = 524287;
 308       emitSPUpdate(MBB, MBBI, NumBytes, TII);
 309     }
 310
 311     MI.getOperand(i).ChangeToImmediate(Offset);
 312   }
 313 }
 314
 315 unsigned SystemZRegisterInfo::getRARegister() const {
 316   assert(0 && "What is the return address register");
 317   return 0;
 318 }
 319
 320 unsigned SystemZRegisterInfo::getFrameRegister(MachineFunction &MF) const {
 321   assert(0 && "What is the frame register");
 322   return 0;
 323 }
 324
 325 unsigned SystemZRegisterInfo::getEHExceptionRegister() const {
 326   assert(0 && "What is the exception register");
 327   return 0;
 328 }
 329
 330 unsigned SystemZRegisterInfo::getEHHandlerRegister() const {
 331   assert(0 && "What is the exception handler register");
 332   return 0;
 333 }
 334
 335 int SystemZRegisterInfo::getDwarfRegNum(unsigned RegNum, bool isEH) const {
 336   assert(0 && "What is the dwarf register number");
 337   return -1;
 338 }
 339
 340 #include "SystemZGenRegisterInfo.inc"