lib/Target/XCore/XCoreFrameLowering.cpp

   1 //===-- XCoreFrameLowering.cpp - Frame info for XCore Target -----*- 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 XCore frame information that doesn't fit anywhere else
  11 // cleanly...
  12 //
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "XCore.h"
  16 #include "XCoreFrameLowering.h"
  17 #include "XCoreInstrInfo.h"
  18 #include "XCoreMachineFunctionInfo.h"
  19 #include "llvm/Function.h"
  20 #include "llvm/CodeGen/MachineFrameInfo.h"
  21 #include "llvm/CodeGen/MachineFunction.h"
  22 #include "llvm/CodeGen/MachineInstrBuilder.h"
  23 #include "llvm/CodeGen/MachineModuleInfo.h"
  24 #include "llvm/CodeGen/MachineRegisterInfo.h"
  25 #include "llvm/CodeGen/RegisterScavenging.h"
  26 #include "llvm/Target/TargetData.h"
  27 #include "llvm/Target/TargetOptions.h"
  28 #include "llvm/Support/ErrorHandling.h"
  29
  30 using namespace llvm;
  31
  32 // helper functions. FIXME: Eliminate.
  33 static inline bool isImmUs(unsigned val) {
  34   return val <= 11;
  35 }
  36
  37 static inline bool isImmU6(unsigned val) {
  38   return val < (1 << 6);
  39 }
  40
  41 static inline bool isImmU16(unsigned val) {
  42   return val < (1 << 16);
  43 }
  44
  45 static void loadFromStack(MachineBasicBlock &MBB,
  46                           MachineBasicBlock::iterator I,
  47                           unsigned DstReg, int Offset, DebugLoc dl,
  48                           const TargetInstrInfo &TII) {
  49   assert(Offset%4 == 0 && "Misaligned stack offset");
  50   Offset/=4;
  51   bool isU6 = isImmU6(Offset);
  52   if (!isU6 && !isImmU16(Offset))
  53     report_fatal_error("loadFromStack offset too big " + Twine(Offset));
  54   int Opcode = isU6 ? XCore::LDWSP_ru6 : XCore::LDWSP_lru6;
  55   BuildMI(MBB, I, dl, TII.get(Opcode), DstReg)
  56     .addImm(Offset);
  57 }
  58
  59
  60 static void storeToStack(MachineBasicBlock &MBB,
  61                          MachineBasicBlock::iterator I,
  62                          unsigned SrcReg, int Offset, DebugLoc dl,
  63                          const TargetInstrInfo &TII) {
  64   assert(Offset%4 == 0 && "Misaligned stack offset");
  65   Offset/=4;
  66   bool isU6 = isImmU6(Offset);
  67   if (!isU6 && !isImmU16(Offset))
  68     report_fatal_error("storeToStack offset too big " + Twine(Offset));
  69   int Opcode = isU6 ? XCore::STWSP_ru6 : XCore::STWSP_lru6;
  70   BuildMI(MBB, I, dl, TII.get(Opcode))
  71     .addReg(SrcReg)
  72     .addImm(Offset);
  73 }
  74
  75
  76 //===----------------------------------------------------------------------===//
  77 // XCoreFrameLowering:
  78 //===----------------------------------------------------------------------===//
  79
  80 XCoreFrameLowering::XCoreFrameLowering(const XCoreSubtarget &sti)
  81   : TargetFrameLowering(TargetFrameLowering::StackGrowsDown, 4, 0),
  82     STI(sti) {
  83   // Do nothing
  84 }
  85
  86 bool XCoreFrameLowering::hasFP(const MachineFunction &MF) const {
  87   return DisableFramePointerElim(MF) || MF.getFrameInfo()->hasVarSizedObjects();
  88 }
  89
  90 void XCoreFrameLowering::emitPrologue(MachineFunction &MF) const {
  91   MachineBasicBlock &MBB = MF.front();   // Prolog goes in entry BB
  92   MachineBasicBlock::iterator MBBI = MBB.begin();
  93   MachineFrameInfo *MFI = MF.getFrameInfo();
  94   MachineModuleInfo *MMI = &MF.getMMI();
  95   const XCoreRegisterInfo *RegInfo =
  96     static_cast<const XCoreRegisterInfo*>(MF.getTarget().getRegisterInfo());
  97   const XCoreInstrInfo &TII =
  98     *static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
  99   XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
 100   DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
 101
 102   bool FP = hasFP(MF);
 103   bool Nested = MF.getFunction()->getAttributes().hasAttrSomewhere(Attribute::Nest);
 104
 105   if (Nested) {
 106     loadFromStack(MBB, MBBI, XCore::R11, 0, dl, TII);
 107   }
 108
 109   // Work out frame sizes.
 110   int FrameSize = MFI->getStackSize();
 111   assert(FrameSize%4 == 0 && "Misaligned frame size");
 112   FrameSize/=4;
 113
 114   bool isU6 = isImmU6(FrameSize);
 115
 116   if (!isU6 && !isImmU16(FrameSize)) {
 117     // FIXME could emit multiple instructions.
 118     report_fatal_error("emitPrologue Frame size too big: " + Twine(FrameSize));
 119   }
 120   bool emitFrameMoves = RegInfo->needsFrameMoves(MF);
 121
 122   // Do we need to allocate space on the stack?
 123   if (FrameSize) {
 124     bool saveLR = XFI->getUsesLR();
 125     bool LRSavedOnEntry = false;
 126     int Opcode;
 127     if (saveLR && (MFI->getObjectOffset(XFI->getLRSpillSlot()) == 0)) {
 128       Opcode = (isU6) ? XCore::ENTSP_u6 : XCore::ENTSP_lu6;
 129       MBB.addLiveIn(XCore::LR);
 130       saveLR = false;
 131       LRSavedOnEntry = true;
 132     } else {
 133       Opcode = (isU6) ? XCore::EXTSP_u6 : XCore::EXTSP_lu6;
 134     }
 135     BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addImm(FrameSize);
 136
 137     if (emitFrameMoves) {
 138       std::vector<MachineMove> &Moves = MMI->getFrameMoves();
 139
 140       // Show update of SP.
 141       MCSymbol *FrameLabel = MMI->getContext().CreateTempSymbol();
 142       BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(FrameLabel);
 143
 144       MachineLocation SPDst(MachineLocation::VirtualFP);
 145       MachineLocation SPSrc(MachineLocation::VirtualFP, -FrameSize * 4);
 146       Moves.push_back(MachineMove(FrameLabel, SPDst, SPSrc));
 147
 148       if (LRSavedOnEntry) {
 149         MachineLocation CSDst(MachineLocation::VirtualFP, 0);
 150         MachineLocation CSSrc(XCore::LR);
 151         Moves.push_back(MachineMove(FrameLabel, CSDst, CSSrc));
 152       }
 153     }
 154     if (saveLR) {
 155       int LRSpillOffset = MFI->getObjectOffset(XFI->getLRSpillSlot());
 156       storeToStack(MBB, MBBI, XCore::LR, LRSpillOffset + FrameSize*4, dl, TII);
 157       MBB.addLiveIn(XCore::LR);
 158
 159       if (emitFrameMoves) {
 160         MCSymbol *SaveLRLabel = MMI->getContext().CreateTempSymbol();
 161         BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(SaveLRLabel);
 162         MachineLocation CSDst(MachineLocation::VirtualFP, LRSpillOffset);
 163         MachineLocation CSSrc(XCore::LR);
 164         MMI->getFrameMoves().push_back(MachineMove(SaveLRLabel, CSDst, CSSrc));
 165       }
 166     }
 167   }
 168
 169   if (FP) {
 170     // Save R10 to the stack.
 171     int FPSpillOffset = MFI->getObjectOffset(XFI->getFPSpillSlot());
 172     storeToStack(MBB, MBBI, XCore::R10, FPSpillOffset + FrameSize*4, dl, TII);
 173     // R10 is live-in. It is killed at the spill.
 174     MBB.addLiveIn(XCore::R10);
 175     if (emitFrameMoves) {
 176       MCSymbol *SaveR10Label = MMI->getContext().CreateTempSymbol();
 177       BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(SaveR10Label);
 178       MachineLocation CSDst(MachineLocation::VirtualFP, FPSpillOffset);
 179       MachineLocation CSSrc(XCore::R10);
 180       MMI->getFrameMoves().push_back(MachineMove(SaveR10Label, CSDst, CSSrc));
 181     }
 182     // Set the FP from the SP.
 183     unsigned FramePtr = XCore::R10;
 184     BuildMI(MBB, MBBI, dl, TII.get(XCore::LDAWSP_ru6), FramePtr)
 185       .addImm(0);
 186     if (emitFrameMoves) {
 187       // Show FP is now valid.
 188       MCSymbol *FrameLabel = MMI->getContext().CreateTempSymbol();
 189       BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(FrameLabel);
 190       MachineLocation SPDst(FramePtr);
 191       MachineLocation SPSrc(MachineLocation::VirtualFP);
 192       MMI->getFrameMoves().push_back(MachineMove(FrameLabel, SPDst, SPSrc));
 193     }
 194   }
 195
 196   if (emitFrameMoves) {
 197     // Frame moves for callee saved.
 198     std::vector<MachineMove> &Moves = MMI->getFrameMoves();
 199     std::vector<std::pair<MCSymbol*, CalleeSavedInfo> >&SpillLabels =
 200         XFI->getSpillLabels();
 201     for (unsigned I = 0, E = SpillLabels.size(); I != E; ++I) {
 202       MCSymbol *SpillLabel = SpillLabels[I].first;
 203       CalleeSavedInfo &CSI = SpillLabels[I].second;
 204       int Offset = MFI->getObjectOffset(CSI.getFrameIdx());
 205       unsigned Reg = CSI.getReg();
 206       MachineLocation CSDst(MachineLocation::VirtualFP, Offset);
 207       MachineLocation CSSrc(Reg);
 208       Moves.push_back(MachineMove(SpillLabel, CSDst, CSSrc));
 209     }
 210   }
 211 }
 212
 213 void XCoreFrameLowering::emitEpilogue(MachineFunction &MF,
 214                                      MachineBasicBlock &MBB) const {
 215   MachineFrameInfo *MFI            = MF.getFrameInfo();
 216   MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
 217   const XCoreInstrInfo &TII =
 218     *static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
 219   DebugLoc dl = MBBI->getDebugLoc();
 220
 221   bool FP = hasFP(MF);
 222   if (FP) {
 223     // Restore the stack pointer.
 224     unsigned FramePtr = XCore::R10;
 225     BuildMI(MBB, MBBI, dl, TII.get(XCore::SETSP_1r))
 226       .addReg(FramePtr);
 227   }
 228
 229   // Work out frame sizes.
 230   int FrameSize = MFI->getStackSize();
 231
 232   assert(FrameSize%4 == 0 && "Misaligned frame size");
 233
 234   FrameSize/=4;
 235
 236   bool isU6 = isImmU6(FrameSize);
 237
 238   if (!isU6 && !isImmU16(FrameSize)) {
 239     // FIXME could emit multiple instructions.
 240     report_fatal_error("emitEpilogue Frame size too big: " + Twine(FrameSize));
 241   }
 242
 243   if (FrameSize) {
 244     XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
 245
 246     if (FP) {
 247       // Restore R10
 248       int FPSpillOffset = MFI->getObjectOffset(XFI->getFPSpillSlot());
 249       FPSpillOffset += FrameSize*4;
 250       loadFromStack(MBB, MBBI, XCore::R10, FPSpillOffset, dl, TII);
 251     }
 252     bool restoreLR = XFI->getUsesLR();
 253     if (restoreLR && MFI->getObjectOffset(XFI->getLRSpillSlot()) != 0) {
 254       int LRSpillOffset = MFI->getObjectOffset(XFI->getLRSpillSlot());
 255       LRSpillOffset += FrameSize*4;
 256       loadFromStack(MBB, MBBI, XCore::LR, LRSpillOffset, dl, TII);
 257       restoreLR = false;
 258     }
 259     if (restoreLR) {
 260       // Fold prologue into return instruction
 261       assert(MBBI->getOpcode() == XCore::RETSP_u6
 262         || MBBI->getOpcode() == XCore::RETSP_lu6);
 263       int Opcode = (isU6) ? XCore::RETSP_u6 : XCore::RETSP_lu6;
 264       BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addImm(FrameSize);
 265       MBB.erase(MBBI);
 266     } else {
 267       int Opcode = (isU6) ? XCore::LDAWSP_ru6_RRegs : XCore::LDAWSP_lru6_RRegs;
 268       BuildMI(MBB, MBBI, dl, TII.get(Opcode), XCore::SP).addImm(FrameSize);
 269     }
 270   }
 271 }
 272
 273 void XCoreFrameLowering::getInitialFrameState(std::vector<MachineMove> &Moves)
 274                                                                         const {
 275   // Initial state of the frame pointer is SP.
 276   MachineLocation Dst(MachineLocation::VirtualFP);
 277   MachineLocation Src(XCore::SP, 0);
 278   Moves.push_back(MachineMove(0, Dst, Src));
 279 }
 280
 281 bool XCoreFrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
 282                                                MachineBasicBlock::iterator MI,
 283                                         const std::vector<CalleeSavedInfo> &CSI,
 284                                           const TargetRegisterInfo *TRI) const {
 285   if (CSI.empty())
 286     return true;
 287
 288   MachineFunction *MF = MBB.getParent();
 289   const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
 290
 291   XCoreFunctionInfo *XFI = MF->getInfo<XCoreFunctionInfo>();
 292   bool emitFrameMoves = XCoreRegisterInfo::needsFrameMoves(*MF);
 293
 294   DebugLoc DL;
 295   if (MI != MBB.end()) DL = MI->getDebugLoc();
 296
 297   for (std::vector<CalleeSavedInfo>::const_iterator it = CSI.begin();
 298                                                     it != CSI.end(); ++it) {
 299     // Add the callee-saved register as live-in. It's killed at the spill.
 300     MBB.addLiveIn(it->getReg());
 301
 302     unsigned Reg = it->getReg();
 303     const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
 304     TII.storeRegToStackSlot(MBB, MI, Reg, true,
 305                             it->getFrameIdx(), RC, TRI);
 306     if (emitFrameMoves) {
 307       MCSymbol *SaveLabel = MF->getContext().CreateTempSymbol();
 308       BuildMI(MBB, MI, DL, TII.get(XCore::PROLOG_LABEL)).addSym(SaveLabel);
 309       XFI->getSpillLabels().push_back(std::make_pair(SaveLabel, *it));
 310     }
 311   }
 312   return true;
 313 }
 314
 315 bool XCoreFrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
 316                                                  MachineBasicBlock::iterator MI,
 317                                         const std::vector<CalleeSavedInfo> &CSI,
 318                                             const TargetRegisterInfo *TRI) const{
 319   MachineFunction *MF = MBB.getParent();
 320   const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
 321
 322   bool AtStart = MI == MBB.begin();
 323   MachineBasicBlock::iterator BeforeI = MI;
 324   if (!AtStart)
 325     --BeforeI;
 326   for (std::vector<CalleeSavedInfo>::const_iterator it = CSI.begin();
 327                                                     it != CSI.end(); ++it) {
 328     unsigned Reg = it->getReg();
 329     const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
 330     TII.loadRegFromStackSlot(MBB, MI, it->getReg(), it->getFrameIdx(),
 331                              RC, TRI);
 332     assert(MI != MBB.begin() &&
 333            "loadRegFromStackSlot didn't insert any code!");
 334     // Insert in reverse order.  loadRegFromStackSlot can insert multiple
 335     // instructions.
 336     if (AtStart)
 337       MI = MBB.begin();
 338     else {
 339       MI = BeforeI;
 340       ++MI;
 341     }
 342   }
 343   return true;
 344 }
 345
 346 void
 347 XCoreFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
 348                                                      RegScavenger *RS) const {
 349   MachineFrameInfo *MFI = MF.getFrameInfo();
 350   const TargetRegisterInfo *RegInfo = MF.getTarget().getRegisterInfo();
 351   bool LRUsed = MF.getRegInfo().isPhysRegUsed(XCore::LR);
 352   const TargetRegisterClass *RC = XCore::GRRegsRegisterClass;
 353   XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
 354   if (LRUsed) {
 355     MF.getRegInfo().setPhysRegUnused(XCore::LR);
 356
 357     bool isVarArg = MF.getFunction()->isVarArg();
 358     int FrameIdx;
 359     if (! isVarArg) {
 360       // A fixed offset of 0 allows us to save / restore LR using entsp / retsp.
 361       FrameIdx = MFI->CreateFixedObject(RC->getSize(), 0, true);
 362     } else {
 363       FrameIdx = MFI->CreateStackObject(RC->getSize(), RC->getAlignment(),
 364                                         false);
 365     }
 366     XFI->setUsesLR(FrameIdx);
 367     XFI->setLRSpillSlot(FrameIdx);
 368   }
 369   if (RegInfo->requiresRegisterScavenging(MF)) {
 370     // Reserve a slot close to SP or frame pointer.
 371     RS->setScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
 372                                                        RC->getAlignment(),
 373                                                        false));
 374   }
 375   if (hasFP(MF)) {
 376     // A callee save register is used to hold the FP.
 377     // This needs saving / restoring in the epilogue / prologue.
 378     XFI->setFPSpillSlot(MFI->CreateStackObject(RC->getSize(),
 379                                                RC->getAlignment(),
 380                                                false));
 381   }
 382 }
 383
 384 void XCoreFrameLowering::
 385 processFunctionBeforeFrameFinalized(MachineFunction &MF) const {
 386
 387 }