1 //===-- ARMFrameLowering.cpp - ARM Frame Information ----------------------===// 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 ARM implementation of TargetFrameLowering class. 11 // 12 //===----------------------------------------------------------------------===// 13 14 #include "ARMFrameLowering.h" 15 #include "ARMBaseInstrInfo.h" 16 #include "ARMBaseRegisterInfo.h" 17 #include "ARMConstantPoolValue.h" 18 #include "ARMMachineFunctionInfo.h" 19 #include "MCTargetDesc/ARMAddressingModes.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/IR/CallingConv.h" 27 #include "llvm/IR/Function.h" 28 #include "llvm/MC/MCContext.h" 29 #include "llvm/Support/CommandLine.h" 30 #include "llvm/Target/TargetOptions.h" 31 32 using namespace llvm; 33 34 static cl::opt<bool> 35 SpillAlignedNEONRegs("align-neon-spills", cl::Hidden, cl::init(true), 36 cl::desc("Align ARM NEON spills in prolog and epilog")); 37 38 static MachineBasicBlock::iterator 39 skipAlignedDPRCS2Spills(MachineBasicBlock::iterator MI, 40 unsigned NumAlignedDPRCS2Regs); 41 42 ARMFrameLowering::ARMFrameLowering(const ARMSubtarget &sti) 43 : TargetFrameLowering(StackGrowsDown, sti.getStackAlignment(), 0, 4), 44 STI(sti) {} 45 46 /// hasFP - Return true if the specified function should have a dedicated frame 47 /// pointer register. This is true if the function has variable sized allocas 48 /// or if frame pointer elimination is disabled. 49 bool ARMFrameLowering::hasFP(const MachineFunction &MF) const { 50 const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo(); 51 52 // iOS requires FP not to be clobbered for backtracing purpose. 53 if (STI.isTargetIOS()) 54 return true; 55 56 const MachineFrameInfo *MFI = MF.getFrameInfo(); 57 // Always eliminate non-leaf frame pointers. 58 return ((MF.getTarget().Options.DisableFramePointerElim(MF) && 59 MFI->hasCalls()) || 60 RegInfo->needsStackRealignment(MF) || 61 MFI->hasVarSizedObjects() || 62 MFI->isFrameAddressTaken()); 63 } 64 65 /// hasReservedCallFrame - Under normal circumstances, when a frame pointer is 66 /// not required, we reserve argument space for call sites in the function 67 /// immediately on entry to the current function. This eliminates the need for 68 /// add/sub sp brackets around call sites. Returns true if the call frame is 69 /// included as part of the stack frame. 70 bool ARMFrameLowering::hasReservedCallFrame(const MachineFunction &MF) const { 71 const MachineFrameInfo *FFI = MF.getFrameInfo(); 72 unsigned CFSize = FFI->getMaxCallFrameSize(); 73 // It's not always a good idea to include the call frame as part of the 74 // stack frame. ARM (especially Thumb) has small immediate offset to 75 // address the stack frame. So a large call frame can cause poor codegen 76 // and may even makes it impossible to scavenge a register. 77 if (CFSize >= ((1 << 12) - 1) / 2) // Half of imm12 78 return false; 79 80 return !MF.getFrameInfo()->hasVarSizedObjects(); 81 } 82 83 /// canSimplifyCallFramePseudos - If there is a reserved call frame, the 84 /// call frame pseudos can be simplified. Unlike most targets, having a FP 85 /// is not sufficient here since we still may reference some objects via SP 86 /// even when FP is available in Thumb2 mode. 87 bool 88 ARMFrameLowering::canSimplifyCallFramePseudos(const MachineFunction &MF) const { 89 return hasReservedCallFrame(MF) || MF.getFrameInfo()->hasVarSizedObjects(); 90 } 91 92 static bool isCSRestore(MachineInstr *MI, 93 const ARMBaseInstrInfo &TII, 94 const MCPhysReg *CSRegs) { 95 // Integer spill area is handled with "pop". 96 if (isPopOpcode(MI->getOpcode())) { 97 // The first two operands are predicates. The last two are 98 // imp-def and imp-use of SP. Check everything in between. 99 for (int i = 5, e = MI->getNumOperands(); i != e; ++i) 100 if (!isCalleeSavedRegister(MI->getOperand(i).getReg(), CSRegs)) 101 return false; 102 return true; 103 } 104 if ((MI->getOpcode() == ARM::LDR_POST_IMM || 105 MI->getOpcode() == ARM::LDR_POST_REG || 106 MI->getOpcode() == ARM::t2LDR_POST) && 107 isCalleeSavedRegister(MI->getOperand(0).getReg(), CSRegs) && 108 MI->getOperand(1).getReg() == ARM::SP) 109 return true; 110 111 return false; 112 } 113 114 static void emitRegPlusImmediate(bool isARM, MachineBasicBlock &MBB, 115 MachineBasicBlock::iterator &MBBI, DebugLoc dl, 116 const ARMBaseInstrInfo &TII, unsigned DestReg, 117 unsigned SrcReg, int NumBytes, 118 unsigned MIFlags = MachineInstr::NoFlags, 119 ARMCC::CondCodes Pred = ARMCC::AL, 120 unsigned PredReg = 0) { 121 if (isARM) 122 emitARMRegPlusImmediate(MBB, MBBI, dl, DestReg, SrcReg, NumBytes, 123 Pred, PredReg, TII, MIFlags); 124 else 125 emitT2RegPlusImmediate(MBB, MBBI, dl, DestReg, SrcReg, NumBytes, 126 Pred, PredReg, TII, MIFlags); 127 } 128 129 static void emitSPUpdate(bool isARM, MachineBasicBlock &MBB, 130 MachineBasicBlock::iterator &MBBI, DebugLoc dl, 131 const ARMBaseInstrInfo &TII, int NumBytes, 132 unsigned MIFlags = MachineInstr::NoFlags, 133 ARMCC::CondCodes Pred = ARMCC::AL, 134 unsigned PredReg = 0) { 135 emitRegPlusImmediate(isARM, MBB, MBBI, dl, TII, ARM::SP, ARM::SP, NumBytes, 136 MIFlags, Pred, PredReg); 137 } 138 139 static int sizeOfSPAdjustment(const MachineInstr *MI) { 140 int RegSize; 141 switch (MI->getOpcode()) { 142 case ARM::VSTMDDB_UPD: 143 RegSize = 8; 144 break; 145 case ARM::STMDB_UPD: 146 case ARM::t2STMDB_UPD: 147 RegSize = 4; 148 break; 149 case ARM::t2STR_PRE: 150 case ARM::STR_PRE_IMM: 151 return 4; 152 default: 153 llvm_unreachable("Unknown push or pop like instruction"); 154 } 155 156 int count = 0; 157 // ARM and Thumb2 push/pop insts have explicit "sp, sp" operands (+ 158 // pred) so the list starts at 4. 159 for (int i = MI->getNumOperands() - 1; i >= 4; --i) 160 count += RegSize; 161 return count; 162 } 163 164 static bool WindowsRequiresStackProbe(const MachineFunction &MF, 165 size_t StackSizeInBytes) { 166 const MachineFrameInfo *MFI = MF.getFrameInfo(); 167 const Function *F = MF.getFunction(); 168 unsigned StackProbeSize = (MFI->getStackProtectorIndex() > 0) ? 4080 : 4096; 169 if (F->hasFnAttribute("stack-probe-size")) 170 F->getFnAttribute("stack-probe-size") 171 .getValueAsString() 172 .getAsInteger(0, StackProbeSize); 173 return StackSizeInBytes >= StackProbeSize; 174 } 175 176 namespace { 177 struct StackAdjustingInsts { 178 struct InstInfo { 179 MachineBasicBlock::iterator I; 180 unsigned SPAdjust; 181 bool BeforeFPSet; 182 }; 183 184 SmallVector<InstInfo, 4> Insts; 185 186 void addInst(MachineBasicBlock::iterator I, unsigned SPAdjust, 187 bool BeforeFPSet = false) { 188 InstInfo Info = {I, SPAdjust, BeforeFPSet}; 189 Insts.push_back(Info); 190 } 191 192 void addExtraBytes(const MachineBasicBlock::iterator I, unsigned ExtraBytes) { 193 auto Info = std::find_if(Insts.begin(), Insts.end(), 194 [&](InstInfo &Info) { return Info.I == I; }); 195 assert(Info != Insts.end() && "invalid sp adjusting instruction"); 196 Info->SPAdjust += ExtraBytes; 197 } 198 199 void emitDefCFAOffsets(MachineModuleInfo &MMI, MachineBasicBlock &MBB, 200 DebugLoc dl, const ARMBaseInstrInfo &TII, bool HasFP) { 201 unsigned CFAOffset = 0; 202 for (auto &Info : Insts) { 203 if (HasFP && !Info.BeforeFPSet) 204 return; 205 206 CFAOffset -= Info.SPAdjust; 207 unsigned CFIIndex = MMI.addFrameInst( 208 MCCFIInstruction::createDefCfaOffset(nullptr, CFAOffset)); 209 BuildMI(MBB, std::next(Info.I), dl, 210 TII.get(TargetOpcode::CFI_INSTRUCTION)) 211 .addCFIIndex(CFIIndex) 212 .setMIFlags(MachineInstr::FrameSetup); 213 } 214 } 215 }; 216 } 217 218 /// Emit an instruction sequence that will align the address in 219 /// register Reg by zero-ing out the lower bits. For versions of the 220 /// architecture that support Neon, this must be done in a single 221 /// instruction, since skipAlignedDPRCS2Spills assumes it is done in a 222 /// single instruction. That function only gets called when optimizing 223 /// spilling of D registers on a core with the Neon instruction set 224 /// present. 225 static void emitAligningInstructions(MachineFunction &MF, ARMFunctionInfo *AFI, 226 const TargetInstrInfo &TII, 227 MachineBasicBlock &MBB, 228 MachineBasicBlock::iterator MBBI, 229 DebugLoc DL, const unsigned Reg, 230 const unsigned Alignment, 231 const bool MustBeSingleInstruction) { 232 const ARMSubtarget &AST = 233 static_cast<const ARMSubtarget &>(MF.getSubtarget()); 234 const bool CanUseBFC = AST.hasV6T2Ops() || AST.hasV7Ops(); 235 const unsigned AlignMask = Alignment - 1; 236 const unsigned NrBitsToZero = countTrailingZeros(Alignment); 237 assert(!AFI->isThumb1OnlyFunction() && "Thumb1 not supported"); 238 if (!AFI->isThumbFunction()) { 239 // if the BFC instruction is available, use that to zero the lower 240 // bits: 241 // bfc Reg, #0, log2(Alignment) 242 // otherwise use BIC, if the mask to zero the required number of bits 243 // can be encoded in the bic immediate field 244 // bic Reg, Reg, Alignment-1 245 // otherwise, emit 246 // lsr Reg, Reg, log2(Alignment) 247 // lsl Reg, Reg, log2(Alignment) 248 if (CanUseBFC) { 249 AddDefaultPred(BuildMI(MBB, MBBI, DL, TII.get(ARM::BFC), Reg) 250 .addReg(Reg, RegState::Kill) 251 .addImm(~AlignMask)); 252 } else if (AlignMask <= 255) { 253 AddDefaultCC( 254 AddDefaultPred(BuildMI(MBB, MBBI, DL, TII.get(ARM::BICri), Reg) 255 .addReg(Reg, RegState::Kill) 256 .addImm(AlignMask))); 257 } else { 258 assert(!MustBeSingleInstruction && 259 "Shouldn't call emitAligningInstructions demanding a single " 260 "instruction to be emitted for large stack alignment for a target " 261 "without BFC."); 262 AddDefaultCC(AddDefaultPred( 263 BuildMI(MBB, MBBI, DL, TII.get(ARM::MOVsi), Reg) 264 .addReg(Reg, RegState::Kill) 265 .addImm(ARM_AM::getSORegOpc(ARM_AM::lsr, NrBitsToZero)))); 266 AddDefaultCC(AddDefaultPred( 267 BuildMI(MBB, MBBI, DL, TII.get(ARM::MOVsi), Reg) 268 .addReg(Reg, RegState::Kill) 269 .addImm(ARM_AM::getSORegOpc(ARM_AM::lsl, NrBitsToZero)))); 270 } 271 } else { 272 // Since this is only reached for Thumb-2 targets, the BFC instruction 273 // should always be available. 274 assert(CanUseBFC); 275 AddDefaultPred(BuildMI(MBB, MBBI, DL, TII.get(ARM::t2BFC), Reg) 276 .addReg(Reg, RegState::Kill) 277 .addImm(~AlignMask)); 278 } 279 } 280 281 void ARMFrameLowering::emitPrologue(MachineFunction &MF, 282 MachineBasicBlock &MBB) const { 283 assert(&MBB == &MF.front() && "Shrink-wrapping not yet implemented"); 284 MachineBasicBlock::iterator MBBI = MBB.begin(); 285 MachineFrameInfo *MFI = MF.getFrameInfo(); 286 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>(); 287 MachineModuleInfo &MMI = MF.getMMI(); 288 MCContext &Context = MMI.getContext(); 289 const TargetMachine &TM = MF.getTarget(); 290 const MCRegisterInfo *MRI = Context.getRegisterInfo(); 291 const ARMBaseRegisterInfo *RegInfo = STI.getRegisterInfo(); 292 const ARMBaseInstrInfo &TII = *STI.getInstrInfo(); 293 assert(!AFI->isThumb1OnlyFunction() && 294 "This emitPrologue does not support Thumb1!"); 295 bool isARM = !AFI->isThumbFunction(); 296 unsigned Align = STI.getFrameLowering()->getStackAlignment(); 297 unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize(); 298 unsigned NumBytes = MFI->getStackSize(); 299 const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo(); 300 DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc(); 301 unsigned FramePtr = RegInfo->getFrameRegister(MF); 302 303 // Determine the sizes of each callee-save spill areas and record which frame 304 // belongs to which callee-save spill areas. 305 unsigned GPRCS1Size = 0, GPRCS2Size = 0, DPRCSSize = 0; 306 int FramePtrSpillFI = 0; 307 int D8SpillFI = 0; 308 309 // All calls are tail calls in GHC calling conv, and functions have no 310 // prologue/epilogue. 311 if (MF.getFunction()->getCallingConv() == CallingConv::GHC) 312 return; 313 314 StackAdjustingInsts DefCFAOffsetCandidates; 315 bool HasFP = hasFP(MF); 316 317 // Allocate the vararg register save area. 318 if (ArgRegsSaveSize) { 319 emitSPUpdate(isARM, MBB, MBBI, dl, TII, -ArgRegsSaveSize, 320 MachineInstr::FrameSetup); 321 DefCFAOffsetCandidates.addInst(std::prev(MBBI), ArgRegsSaveSize, true); 322 } 323 324 if (!AFI->hasStackFrame() && 325 (!STI.isTargetWindows() || !WindowsRequiresStackProbe(MF, NumBytes))) { 326 if (NumBytes - ArgRegsSaveSize != 0) { 327 emitSPUpdate(isARM, MBB, MBBI, dl, TII, -(NumBytes - ArgRegsSaveSize), 328 MachineInstr::FrameSetup); 329 DefCFAOffsetCandidates.addInst(std::prev(MBBI), 330 NumBytes - ArgRegsSaveSize, true); 331 } 332 DefCFAOffsetCandidates.emitDefCFAOffsets(MMI, MBB, dl, TII, HasFP); 333 return; 334 } 335 336 // Determine spill area sizes. 337 for (unsigned i = 0, e = CSI.size(); i != e; ++i) { 338 unsigned Reg = CSI[i].getReg(); 339 int FI = CSI[i].getFrameIdx(); 340 switch (Reg) { 341 case ARM::R8: 342 case ARM::R9: 343 case ARM::R10: 344 case ARM::R11: 345 case ARM::R12: 346 if (STI.isTargetDarwin()) { 347 GPRCS2Size += 4; 348 break; 349 } 350 // fallthrough 351 case ARM::R0: 352 case ARM::R1: 353 case ARM::R2: 354 case ARM::R3: 355 case ARM::R4: 356 case ARM::R5: 357 case ARM::R6: 358 case ARM::R7: 359 case ARM::LR: 360 if (Reg == FramePtr) 361 FramePtrSpillFI = FI; 362 GPRCS1Size += 4; 363 break; 364 default: 365 // This is a DPR. Exclude the aligned DPRCS2 spills. 366 if (Reg == ARM::D8) 367 D8SpillFI = FI; 368 if (Reg < ARM::D8 || Reg >= ARM::D8 + AFI->getNumAlignedDPRCS2Regs()) 369 DPRCSSize += 8; 370 } 371 } 372 373 // Move past area 1. 374 MachineBasicBlock::iterator LastPush = MBB.end(), GPRCS1Push, GPRCS2Push; 375 if (GPRCS1Size > 0) { 376 GPRCS1Push = LastPush = MBBI++; 377 DefCFAOffsetCandidates.addInst(LastPush, GPRCS1Size, true); 378 } 379 380 // Determine starting offsets of spill areas. 381 unsigned GPRCS1Offset = NumBytes - ArgRegsSaveSize - GPRCS1Size; 382 unsigned GPRCS2Offset = GPRCS1Offset - GPRCS2Size; 383 unsigned DPRAlign = DPRCSSize ? std::min(8U, Align) : 4U; 384 unsigned DPRGapSize = (GPRCS1Size + GPRCS2Size + ArgRegsSaveSize) % DPRAlign; 385 unsigned DPRCSOffset = GPRCS2Offset - DPRGapSize - DPRCSSize; 386 int FramePtrOffsetInPush = 0; 387 if (HasFP) { 388 FramePtrOffsetInPush = 389 MFI->getObjectOffset(FramePtrSpillFI) + ArgRegsSaveSize; 390 AFI->setFramePtrSpillOffset(MFI->getObjectOffset(FramePtrSpillFI) + 391 NumBytes); 392 } 393 AFI->setGPRCalleeSavedArea1Offset(GPRCS1Offset); 394 AFI->setGPRCalleeSavedArea2Offset(GPRCS2Offset); 395 AFI->setDPRCalleeSavedAreaOffset(DPRCSOffset); 396 397 // Move past area 2. 398 if (GPRCS2Size > 0) { 399 GPRCS2Push = LastPush = MBBI++; 400 DefCFAOffsetCandidates.addInst(LastPush, GPRCS2Size); 401 } 402 403 // Prolog/epilog inserter assumes we correctly align DPRs on the stack, so our 404 // .cfi_offset operations will reflect that. 405 if (DPRGapSize) { 406 assert(DPRGapSize == 4 && "unexpected alignment requirements for DPRs"); 407 if (tryFoldSPUpdateIntoPushPop(STI, MF, LastPush, DPRGapSize)) 408 DefCFAOffsetCandidates.addExtraBytes(LastPush, DPRGapSize); 409 else { 410 emitSPUpdate(isARM, MBB, MBBI, dl, TII, -DPRGapSize, 411 MachineInstr::FrameSetup); 412 DefCFAOffsetCandidates.addInst(std::prev(MBBI), DPRGapSize); 413 } 414 } 415 416 // Move past area 3. 417 if (DPRCSSize > 0) { 418 // Since vpush register list cannot have gaps, there may be multiple vpush 419 // instructions in the prologue. 420 while (MBBI->getOpcode() == ARM::VSTMDDB_UPD) { 421 DefCFAOffsetCandidates.addInst(MBBI, sizeOfSPAdjustment(MBBI)); 422 LastPush = MBBI++; 423 } 424 } 425 426 // Move past the aligned DPRCS2 area. 427 if (AFI->getNumAlignedDPRCS2Regs() > 0) { 428 MBBI = skipAlignedDPRCS2Spills(MBBI, AFI->getNumAlignedDPRCS2Regs()); 429 // The code inserted by emitAlignedDPRCS2Spills realigns the stack, and 430 // leaves the stack pointer pointing to the DPRCS2 area. 431 // 432 // Adjust NumBytes to represent the stack slots below the DPRCS2 area. 433 NumBytes += MFI->getObjectOffset(D8SpillFI); 434 } else 435 NumBytes = DPRCSOffset; 436 437 if (STI.isTargetWindows() && WindowsRequiresStackProbe(MF, NumBytes)) { 438 uint32_t NumWords = NumBytes >> 2; 439 440 if (NumWords < 65536) 441 AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::t2MOVi16), ARM::R4) 442 .addImm(NumWords) 443 .setMIFlags(MachineInstr::FrameSetup)); 444 else 445 BuildMI(MBB, MBBI, dl, TII.get(ARM::t2MOVi32imm), ARM::R4) 446 .addImm(NumWords) 447 .setMIFlags(MachineInstr::FrameSetup); 448 449 switch (TM.getCodeModel()) { 450 case CodeModel::Small: 451 case CodeModel::Medium: 452 case CodeModel::Default: 453 case CodeModel::Kernel: 454 BuildMI(MBB, MBBI, dl, TII.get(ARM::tBL)) 455 .addImm((unsigned)ARMCC::AL).addReg(0) 456 .addExternalSymbol("__chkstk") 457 .addReg(ARM::R4, RegState::Implicit) 458 .setMIFlags(MachineInstr::FrameSetup); 459 break; 460 case CodeModel::Large: 461 case CodeModel::JITDefault: 462 BuildMI(MBB, MBBI, dl, TII.get(ARM::t2MOVi32imm), ARM::R12) 463 .addExternalSymbol("__chkstk") 464 .setMIFlags(MachineInstr::FrameSetup); 465 466 BuildMI(MBB, MBBI, dl, TII.get(ARM::tBLXr)) 467 .addImm((unsigned)ARMCC::AL).addReg(0) 468 .addReg(ARM::R12, RegState::Kill) 469 .addReg(ARM::R4, RegState::Implicit) 470 .setMIFlags(MachineInstr::FrameSetup); 471 break; 472 } 473 474 AddDefaultCC(AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::t2SUBrr), 475 ARM::SP) 476 .addReg(ARM::SP, RegState::Define) 477 .addReg(ARM::R4, RegState::Kill) 478 .setMIFlags(MachineInstr::FrameSetup))); 479 NumBytes = 0; 480 } 481 482 if (NumBytes) { 483 // Adjust SP after all the callee-save spills. 484 if (tryFoldSPUpdateIntoPushPop(STI, MF, LastPush, NumBytes)) 485 DefCFAOffsetCandidates.addExtraBytes(LastPush, NumBytes); 486 else { 487 emitSPUpdate(isARM, MBB, MBBI, dl, TII, -NumBytes, 488 MachineInstr::FrameSetup); 489 DefCFAOffsetCandidates.addInst(std::prev(MBBI), NumBytes); 490 } 491 492 if (HasFP && isARM) 493 // Restore from fp only in ARM mode: e.g. sub sp, r7, #24 494 // Note it's not safe to do this in Thumb2 mode because it would have 495 // taken two instructions: 496 // mov sp, r7 497 // sub sp, #24 498 // If an interrupt is taken between the two instructions, then sp is in 499 // an inconsistent state (pointing to the middle of callee-saved area). 500 // The interrupt handler can end up clobbering the registers. 501 AFI->setShouldRestoreSPFromFP(true); 502 } 503 504 // Set FP to point to the stack slot that contains the previous FP. 505 // For iOS, FP is R7, which has now been stored in spill area 1. 506 // Otherwise, if this is not iOS, all the callee-saved registers go 507 // into spill area 1, including the FP in R11. In either case, it 508 // is in area one and the adjustment needs to take place just after 509 // that push. 510 if (HasFP) { 511 MachineBasicBlock::iterator AfterPush = std::next(GPRCS1Push); 512 unsigned PushSize = sizeOfSPAdjustment(GPRCS1Push); 513 emitRegPlusImmediate(!AFI->isThumbFunction(), MBB, AfterPush, 514 dl, TII, FramePtr, ARM::SP, 515 PushSize + FramePtrOffsetInPush, 516 MachineInstr::FrameSetup); 517 if (FramePtrOffsetInPush + PushSize != 0) { 518 unsigned CFIIndex = MMI.addFrameInst(MCCFIInstruction::createDefCfa( 519 nullptr, MRI->getDwarfRegNum(FramePtr, true), 520 -(ArgRegsSaveSize - FramePtrOffsetInPush))); 521 BuildMI(MBB, AfterPush, dl, TII.get(TargetOpcode::CFI_INSTRUCTION)) 522 .addCFIIndex(CFIIndex) 523 .setMIFlags(MachineInstr::FrameSetup); 524 } else { 525 unsigned CFIIndex = 526 MMI.addFrameInst(MCCFIInstruction::createDefCfaRegister( 527 nullptr, MRI->getDwarfRegNum(FramePtr, true))); 528 BuildMI(MBB, AfterPush, dl, TII.get(TargetOpcode::CFI_INSTRUCTION)) 529 .addCFIIndex(CFIIndex) 530 .setMIFlags(MachineInstr::FrameSetup); 531 } 532 } 533 534 // Now that the prologue's actual instructions are finalised, we can insert 535 // the necessary DWARF cf instructions to describe the situation. Start by 536 // recording where each register ended up: 537 if (GPRCS1Size > 0) { 538 MachineBasicBlock::iterator Pos = std::next(GPRCS1Push); 539 int CFIIndex; 540 for (const auto &Entry : CSI) { 541 unsigned Reg = Entry.getReg(); 542 int FI = Entry.getFrameIdx(); 543 switch (Reg) { 544 case ARM::R8: 545 case ARM::R9: 546 case ARM::R10: 547 case ARM::R11: 548 case ARM::R12: 549 if (STI.isTargetDarwin()) 550 break; 551 // fallthrough 552 case ARM::R0: 553 case ARM::R1: 554 case ARM::R2: 555 case ARM::R3: 556 case ARM::R4: 557 case ARM::R5: 558 case ARM::R6: 559 case ARM::R7: 560 case ARM::LR: 561 CFIIndex = MMI.addFrameInst(MCCFIInstruction::createOffset( 562 nullptr, MRI->getDwarfRegNum(Reg, true), MFI->getObjectOffset(FI))); 563 BuildMI(MBB, Pos, dl, TII.get(TargetOpcode::CFI_INSTRUCTION)) 564 .addCFIIndex(CFIIndex) 565 .setMIFlags(MachineInstr::FrameSetup); 566 break; 567 } 568 } 569 } 570 571 if (GPRCS2Size > 0) { 572 MachineBasicBlock::iterator Pos = std::next(GPRCS2Push); 573 for (const auto &Entry : CSI) { 574 unsigned Reg = Entry.getReg(); 575 int FI = Entry.getFrameIdx(); 576 switch (Reg) { 577 case ARM::R8: 578 case ARM::R9: 579 case ARM::R10: 580 case ARM::R11: 581 case ARM::R12: 582 if (STI.isTargetDarwin()) { 583 unsigned DwarfReg = MRI->getDwarfRegNum(Reg, true); 584 unsigned Offset = MFI->getObjectOffset(FI); 585 unsigned CFIIndex = MMI.addFrameInst( 586 MCCFIInstruction::createOffset(nullptr, DwarfReg, Offset)); 587 BuildMI(MBB, Pos, dl, TII.get(TargetOpcode::CFI_INSTRUCTION)) 588 .addCFIIndex(CFIIndex) 589 .setMIFlags(MachineInstr::FrameSetup); 590 } 591 break; 592 } 593 } 594 } 595 596 if (DPRCSSize > 0) { 597 // Since vpush register list cannot have gaps, there may be multiple vpush 598 // instructions in the prologue. 599 MachineBasicBlock::iterator Pos = std::next(LastPush); 600 for (const auto &Entry : CSI) { 601 unsigned Reg = Entry.getReg(); 602 int FI = Entry.getFrameIdx(); 603 if ((Reg >= ARM::D0 && Reg <= ARM::D31) && 604 (Reg < ARM::D8 || Reg >= ARM::D8 + AFI->getNumAlignedDPRCS2Regs())) { 605 unsigned DwarfReg = MRI->getDwarfRegNum(Reg, true); 606 unsigned Offset = MFI->getObjectOffset(FI); 607 unsigned CFIIndex = MMI.addFrameInst( 608 MCCFIInstruction::createOffset(nullptr, DwarfReg, Offset)); 609 BuildMI(MBB, Pos, dl, TII.get(TargetOpcode::CFI_INSTRUCTION)) 610 .addCFIIndex(CFIIndex) 611 .setMIFlags(MachineInstr::FrameSetup); 612 } 613 } 614 } 615 616 // Now we can emit descriptions of where the canonical frame address was 617 // throughout the process. If we have a frame pointer, it takes over the job 618 // half-way through, so only the first few .cfi_def_cfa_offset instructions 619 // actually get emitted. 620 DefCFAOffsetCandidates.emitDefCFAOffsets(MMI, MBB, dl, TII, HasFP); 621 622 if (STI.isTargetELF() && hasFP(MF)) 623 MFI->setOffsetAdjustment(MFI->getOffsetAdjustment() - 624 AFI->getFramePtrSpillOffset()); 625 626 AFI->setGPRCalleeSavedArea1Size(GPRCS1Size); 627 AFI->setGPRCalleeSavedArea2Size(GPRCS2Size); 628 AFI->setDPRCalleeSavedGapSize(DPRGapSize); 629 AFI->setDPRCalleeSavedAreaSize(DPRCSSize); 630 631 // If we need dynamic stack realignment, do it here. Be paranoid and make 632 // sure if we also have VLAs, we have a base pointer for frame access. 633 // If aligned NEON registers were spilled, the stack has already been 634 // realigned. 635 if (!AFI->getNumAlignedDPRCS2Regs() && RegInfo->needsStackRealignment(MF)) { 636 unsigned MaxAlign = MFI->getMaxAlignment(); 637 assert(!AFI->isThumb1OnlyFunction()); 638 if (!AFI->isThumbFunction()) { 639 emitAligningInstructions(MF, AFI, TII, MBB, MBBI, dl, ARM::SP, MaxAlign, 640 false); 641 } else { 642 // We cannot use sp as source/dest register here, thus we're using r4 to 643 // perform the calculations. We're emitting the following sequence: 644 // mov r4, sp 645 // -- use emitAligningInstructions to produce best sequence to zero 646 // -- out lower bits in r4 647 // mov sp, r4 648 // FIXME: It will be better just to find spare register here. 649 AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), ARM::R4) 650 .addReg(ARM::SP, RegState::Kill)); 651 emitAligningInstructions(MF, AFI, TII, MBB, MBBI, dl, ARM::R4, MaxAlign, 652 false); 653 AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), ARM::SP) 654 .addReg(ARM::R4, RegState::Kill)); 655 } 656 657 AFI->setShouldRestoreSPFromFP(true); 658 } 659 660 // If we need a base pointer, set it up here. It's whatever the value 661 // of the stack pointer is at this point. Any variable size objects 662 // will be allocated after this, so we can still use the base pointer 663 // to reference locals. 664 // FIXME: Clarify FrameSetup flags here. 665 if (RegInfo->hasBasePointer(MF)) { 666 if (isARM) 667 BuildMI(MBB, MBBI, dl, 668 TII.get(ARM::MOVr), RegInfo->getBaseRegister()) 669 .addReg(ARM::SP) 670 .addImm((unsigned)ARMCC::AL).addReg(0).addReg(0); 671 else 672 AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), 673 RegInfo->getBaseRegister()) 674 .addReg(ARM::SP)); 675 } 676 677 // If the frame has variable sized objects then the epilogue must restore 678 // the sp from fp. We can assume there's an FP here since hasFP already 679 // checks for hasVarSizedObjects. 680 if (MFI->hasVarSizedObjects()) 681 AFI->setShouldRestoreSPFromFP(true); 682 } 683 684 // Resolve TCReturn pseudo-instruction 685 void ARMFrameLowering::fixTCReturn(MachineFunction &MF, 686 MachineBasicBlock &MBB) const { 687 MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr(); 688 assert(MBBI->isReturn() && "Can only insert epilog into returning blocks"); 689 unsigned RetOpcode = MBBI->getOpcode(); 690 DebugLoc dl = MBBI->getDebugLoc(); 691 const ARMBaseInstrInfo &TII = 692 *static_cast<const ARMBaseInstrInfo *>(MF.getSubtarget().getInstrInfo()); 693 694 if (!(RetOpcode == ARM::TCRETURNdi || RetOpcode == ARM::TCRETURNri)) 695 return; 696 697 // Tail call return: adjust the stack pointer and jump to callee. 698 MBBI = MBB.getLastNonDebugInstr(); 699 MachineOperand &JumpTarget = MBBI->getOperand(0); 700 701 // Jump to label or value in register. 702 if (RetOpcode == ARM::TCRETURNdi) { 703 unsigned TCOpcode = STI.isThumb() ? 704 (STI.isTargetMachO() ? ARM::tTAILJMPd : ARM::tTAILJMPdND) : 705 ARM::TAILJMPd; 706 MachineInstrBuilder MIB = BuildMI(MBB, MBBI, dl, TII.get(TCOpcode)); 707 if (JumpTarget.isGlobal()) 708 MIB.addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(), 709 JumpTarget.getTargetFlags()); 710 else { 711 assert(JumpTarget.isSymbol()); 712 MIB.addExternalSymbol(JumpTarget.getSymbolName(), 713 JumpTarget.getTargetFlags()); 714 } 715 716 // Add the default predicate in Thumb mode. 717 if (STI.isThumb()) MIB.addImm(ARMCC::AL).addReg(0); 718 } else if (RetOpcode == ARM::TCRETURNri) { 719 BuildMI(MBB, MBBI, dl, 720 TII.get(STI.isThumb() ? ARM::tTAILJMPr : ARM::TAILJMPr)). 721 addReg(JumpTarget.getReg(), RegState::Kill); 722 } 723 724 MachineInstr *NewMI = std::prev(MBBI); 725 for (unsigned i = 1, e = MBBI->getNumOperands(); i != e; ++i) 726 NewMI->addOperand(MBBI->getOperand(i)); 727 728 // Delete the pseudo instruction TCRETURN. 729 MBB.erase(MBBI); 730 MBBI = NewMI; 731 } 732 733 void ARMFrameLowering::emitEpilogue(MachineFunction &MF, 734 MachineBasicBlock &MBB) const { 735 MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr(); 736 assert(MBBI->isReturn() && "Can only insert epilog into returning blocks"); 737 DebugLoc dl = MBBI->getDebugLoc(); 738 MachineFrameInfo *MFI = MF.getFrameInfo(); 739 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>(); 740 const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo(); 741 const ARMBaseInstrInfo &TII = 742 *static_cast<const ARMBaseInstrInfo *>(MF.getSubtarget().getInstrInfo()); 743 assert(!AFI->isThumb1OnlyFunction() && 744 "This emitEpilogue does not support Thumb1!"); 745 bool isARM = !AFI->isThumbFunction(); 746 747 unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize(); 748 int NumBytes = (int)MFI->getStackSize(); 749 unsigned FramePtr = RegInfo->getFrameRegister(MF); 750 751 // All calls are tail calls in GHC calling conv, and functions have no 752 // prologue/epilogue. 753 if (MF.getFunction()->getCallingConv() == CallingConv::GHC) { 754 fixTCReturn(MF, MBB); 755 return; 756 } 757 758 if (!AFI->hasStackFrame()) { 759 if (NumBytes - ArgRegsSaveSize != 0) 760 emitSPUpdate(isARM, MBB, MBBI, dl, TII, NumBytes - ArgRegsSaveSize); 761 } else { 762 // Unwind MBBI to point to first LDR / VLDRD. 763 const MCPhysReg *CSRegs = RegInfo->getCalleeSavedRegs(&MF); 764 if (MBBI != MBB.begin()) { 765 do { 766 --MBBI; 767 } while (MBBI != MBB.begin() && isCSRestore(MBBI, TII, CSRegs)); 768 if (!isCSRestore(MBBI, TII, CSRegs)) 769 ++MBBI; 770 } 771 772 // Move SP to start of FP callee save spill area. 773 NumBytes -= (ArgRegsSaveSize + 774 AFI->getGPRCalleeSavedArea1Size() + 775 AFI->getGPRCalleeSavedArea2Size() + 776 AFI->getDPRCalleeSavedGapSize() + 777 AFI->getDPRCalleeSavedAreaSize()); 778 779 // Reset SP based on frame pointer only if the stack frame extends beyond 780 // frame pointer stack slot or target is ELF and the function has FP. 781 if (AFI->shouldRestoreSPFromFP()) { 782 NumBytes = AFI->getFramePtrSpillOffset() - NumBytes; 783 if (NumBytes) { 784 if (isARM) 785 emitARMRegPlusImmediate(MBB, MBBI, dl, ARM::SP, FramePtr, -NumBytes, 786 ARMCC::AL, 0, TII); 787 else { 788 // It's not possible to restore SP from FP in a single instruction. 789 // For iOS, this looks like: 790 // mov sp, r7 791 // sub sp, #24 792 // This is bad, if an interrupt is taken after the mov, sp is in an 793 // inconsistent state. 794 // Use the first callee-saved register as a scratch register. 795 assert(MF.getRegInfo().isPhysRegUsed(ARM::R4) && 796 "No scratch register to restore SP from FP!"); 797 emitT2RegPlusImmediate(MBB, MBBI, dl, ARM::R4, FramePtr, -NumBytes, 798 ARMCC::AL, 0, TII); 799 AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), 800 ARM::SP) 801 .addReg(ARM::R4)); 802 } 803 } else { 804 // Thumb2 or ARM. 805 if (isARM) 806 BuildMI(MBB, MBBI, dl, TII.get(ARM::MOVr), ARM::SP) 807 .addReg(FramePtr).addImm((unsigned)ARMCC::AL).addReg(0).addReg(0); 808 else 809 AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), 810 ARM::SP) 811 .addReg(FramePtr)); 812 } 813 } else if (NumBytes && 814 !tryFoldSPUpdateIntoPushPop(STI, MF, MBBI, NumBytes)) 815 emitSPUpdate(isARM, MBB, MBBI, dl, TII, NumBytes); 816 817 // Increment past our save areas. 818 if (AFI->getDPRCalleeSavedAreaSize()) { 819 MBBI++; 820 // Since vpop register list cannot have gaps, there may be multiple vpop 821 // instructions in the epilogue. 822 while (MBBI->getOpcode() == ARM::VLDMDIA_UPD) 823 MBBI++; 824 } 825 if (AFI->getDPRCalleeSavedGapSize()) { 826 assert(AFI->getDPRCalleeSavedGapSize() == 4 && 827 "unexpected DPR alignment gap"); 828 emitSPUpdate(isARM, MBB, MBBI, dl, TII, AFI->getDPRCalleeSavedGapSize()); 829 } 830 831 if (AFI->getGPRCalleeSavedArea2Size()) MBBI++; 832 if (AFI->getGPRCalleeSavedArea1Size()) MBBI++; 833 } 834 835 fixTCReturn(MF, MBB); 836 837 if (ArgRegsSaveSize) 838 emitSPUpdate(isARM, MBB, MBBI, dl, TII, ArgRegsSaveSize); 839 } 840 841 /// getFrameIndexReference - Provide a base+offset reference to an FI slot for 842 /// debug info. It's the same as what we use for resolving the code-gen 843 /// references for now. FIXME: This can go wrong when references are 844 /// SP-relative and simple call frames aren't used. 845 int 846 ARMFrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI, 847 unsigned &FrameReg) const { 848 return ResolveFrameIndexReference(MF, FI, FrameReg, 0); 849 } 850 851 int 852 ARMFrameLowering::ResolveFrameIndexReference(const MachineFunction &MF, 853 int FI, unsigned &FrameReg, 854 int SPAdj) const { 855 const MachineFrameInfo *MFI = MF.getFrameInfo(); 856 const ARMBaseRegisterInfo *RegInfo = static_cast<const ARMBaseRegisterInfo *>( 857 MF.getSubtarget().getRegisterInfo()); 858 const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>(); 859 int Offset = MFI->getObjectOffset(FI) + MFI->getStackSize(); 860 int FPOffset = Offset - AFI->getFramePtrSpillOffset(); 861 bool isFixed = MFI->isFixedObjectIndex(FI); 862 863 FrameReg = ARM::SP; 864 Offset += SPAdj; 865 866 // SP can move around if there are allocas. We may also lose track of SP 867 // when emergency spilling inside a non-reserved call frame setup. 868 bool hasMovingSP = !hasReservedCallFrame(MF); 869 870 // When dynamically realigning the stack, use the frame pointer for 871 // parameters, and the stack/base pointer for locals. 872 if (RegInfo->needsStackRealignment(MF)) { 873 assert (hasFP(MF) && "dynamic stack realignment without a FP!"); 874 if (isFixed) { 875 FrameReg = RegInfo->getFrameRegister(MF); 876 Offset = FPOffset; 877 } else if (hasMovingSP) { 878 assert(RegInfo->hasBasePointer(MF) && 879 "VLAs and dynamic stack alignment, but missing base pointer!"); 880 FrameReg = RegInfo->getBaseRegister(); 881 } 882 return Offset; 883 } 884 885 // If there is a frame pointer, use it when we can. 886 if (hasFP(MF) && AFI->hasStackFrame()) { 887 // Use frame pointer to reference fixed objects. Use it for locals if 888 // there are VLAs (and thus the SP isn't reliable as a base). 889 if (isFixed || (hasMovingSP && !RegInfo->hasBasePointer(MF))) { 890 FrameReg = RegInfo->getFrameRegister(MF); 891 return FPOffset; 892 } else if (hasMovingSP) { 893 assert(RegInfo->hasBasePointer(MF) && "missing base pointer!"); 894 if (AFI->isThumb2Function()) { 895 // Try to use the frame pointer if we can, else use the base pointer 896 // since it's available. This is handy for the emergency spill slot, in 897 // particular. 898 if (FPOffset >= -255 && FPOffset < 0) { 899 FrameReg = RegInfo->getFrameRegister(MF); 900 return FPOffset; 901 } 902 } 903 } else if (AFI->isThumb2Function()) { 904 // Use add <rd>, sp, #<imm8> 905 // ldr <rd>, [sp, #<imm8>] 906 // if at all possible to save space. 907 if (Offset >= 0 && (Offset & 3) == 0 && Offset <= 1020) 908 return Offset; 909 // In Thumb2 mode, the negative offset is very limited. Try to avoid 910 // out of range references. ldr <rt>,[<rn>, #-<imm8>] 911 if (FPOffset >= -255 && FPOffset < 0) { 912 FrameReg = RegInfo->getFrameRegister(MF); 913 return FPOffset; 914 } 915 } else if (Offset > (FPOffset < 0 ? -FPOffset : FPOffset)) { 916 // Otherwise, use SP or FP, whichever is closer to the stack slot. 917 FrameReg = RegInfo->getFrameRegister(MF); 918 return FPOffset; 919 } 920 } 921 // Use the base pointer if we have one. 922 if (RegInfo->hasBasePointer(MF)) 923 FrameReg = RegInfo->getBaseRegister(); 924 return Offset; 925 } 926 927 int ARMFrameLowering::getFrameIndexOffset(const MachineFunction &MF, 928 int FI) const { 929 unsigned FrameReg; 930 return getFrameIndexReference(MF, FI, FrameReg); 931 } 932 933 void ARMFrameLowering::emitPushInst(MachineBasicBlock &MBB, 934 MachineBasicBlock::iterator MI, 935 const std::vector<CalleeSavedInfo> &CSI, 936 unsigned StmOpc, unsigned StrOpc, 937 bool NoGap, 938 bool(*Func)(unsigned, bool), 939 unsigned NumAlignedDPRCS2Regs, 940 unsigned MIFlags) const { 941 MachineFunction &MF = *MBB.getParent(); 942 const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); 943 944 DebugLoc DL; 945 if (MI != MBB.end()) DL = MI->getDebugLoc(); 946 947 SmallVector<std::pair<unsigned,bool>, 4> Regs; 948 unsigned i = CSI.size(); 949 while (i != 0) { 950 unsigned LastReg = 0; 951 for (; i != 0; --i) { 952 unsigned Reg = CSI[i-1].getReg(); 953 if (!(Func)(Reg, STI.isTargetDarwin())) continue; 954 955 // D-registers in the aligned area DPRCS2 are NOT spilled here. 956 if (Reg >= ARM::D8 && Reg < ARM::D8 + NumAlignedDPRCS2Regs) 957 continue; 958 959 // Add the callee-saved register as live-in unless it's LR and 960 // @llvm.returnaddress is called. If LR is returned for 961 // @llvm.returnaddress then it's already added to the function and 962 // entry block live-in sets. 963 bool isKill = true; 964 if (Reg == ARM::LR) { 965 if (MF.getFrameInfo()->isReturnAddressTaken() && 966 MF.getRegInfo().isLiveIn(Reg)) 967 isKill = false; 968 } 969 970 if (isKill) 971 MBB.addLiveIn(Reg); 972 973 // If NoGap is true, push consecutive registers and then leave the rest 974 // for other instructions. e.g. 975 // vpush {d8, d10, d11} -> vpush {d8}, vpush {d10, d11} 976 if (NoGap && LastReg && LastReg != Reg-1) 977 break; 978 LastReg = Reg; 979 Regs.push_back(std::make_pair(Reg, isKill)); 980 } 981 982 if (Regs.empty()) 983 continue; 984 if (Regs.size() > 1 || StrOpc== 0) { 985 MachineInstrBuilder MIB = 986 AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(StmOpc), ARM::SP) 987 .addReg(ARM::SP).setMIFlags(MIFlags)); 988 for (unsigned i = 0, e = Regs.size(); i < e; ++i) 989 MIB.addReg(Regs[i].first, getKillRegState(Regs[i].second)); 990 } else if (Regs.size() == 1) { 991 MachineInstrBuilder MIB = BuildMI(MBB, MI, DL, TII.get(StrOpc), 992 ARM::SP) 993 .addReg(Regs[0].first, getKillRegState(Regs[0].second)) 994 .addReg(ARM::SP).setMIFlags(MIFlags) 995 .addImm(-4); 996 AddDefaultPred(MIB); 997 } 998 Regs.clear(); 999 1000 // Put any subsequent vpush instructions before this one: they will refer to 1001 // higher register numbers so need to be pushed first in order to preserve 1002 // monotonicity. 1003 --MI; 1004 } 1005 } 1006 1007 void ARMFrameLowering::emitPopInst(MachineBasicBlock &MBB, 1008 MachineBasicBlock::iterator MI, 1009 const std::vector<CalleeSavedInfo> &CSI, 1010 unsigned LdmOpc, unsigned LdrOpc, 1011 bool isVarArg, bool NoGap, 1012 bool(*Func)(unsigned, bool), 1013 unsigned NumAlignedDPRCS2Regs) const { 1014 MachineFunction &MF = *MBB.getParent(); 1015 const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); 1016 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>(); 1017 DebugLoc DL = MI->getDebugLoc(); 1018 unsigned RetOpcode = MI->getOpcode(); 1019 bool isTailCall = (RetOpcode == ARM::TCRETURNdi || 1020 RetOpcode == ARM::TCRETURNri); 1021 bool isInterrupt = 1022 RetOpcode == ARM::SUBS_PC_LR || RetOpcode == ARM::t2SUBS_PC_LR; 1023 1024 SmallVector<unsigned, 4> Regs; 1025 unsigned i = CSI.size(); 1026 while (i != 0) { 1027 unsigned LastReg = 0; 1028 bool DeleteRet = false; 1029 for (; i != 0; --i) { 1030 unsigned Reg = CSI[i-1].getReg(); 1031 if (!(Func)(Reg, STI.isTargetDarwin())) continue; 1032 1033 // The aligned reloads from area DPRCS2 are not inserted here. 1034 if (Reg >= ARM::D8 && Reg < ARM::D8 + NumAlignedDPRCS2Regs) 1035 continue; 1036 1037 if (Reg == ARM::LR && !isTailCall && !isVarArg && !isInterrupt && 1038 STI.hasV5TOps()) { 1039 Reg = ARM::PC; 1040 LdmOpc = AFI->isThumbFunction() ? ARM::t2LDMIA_RET : ARM::LDMIA_RET; 1041 // Fold the return instruction into the LDM. 1042 DeleteRet = true; 1043 } 1044 1045 // If NoGap is true, pop consecutive registers and then leave the rest 1046 // for other instructions. e.g. 1047 // vpop {d8, d10, d11} -> vpop {d8}, vpop {d10, d11} 1048 if (NoGap && LastReg && LastReg != Reg-1) 1049 break; 1050 1051 LastReg = Reg; 1052 Regs.push_back(Reg); 1053 } 1054 1055 if (Regs.empty()) 1056 continue; 1057 if (Regs.size() > 1 || LdrOpc == 0) { 1058 MachineInstrBuilder MIB = 1059 AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(LdmOpc), ARM::SP) 1060 .addReg(ARM::SP)); 1061 for (unsigned i = 0, e = Regs.size(); i < e; ++i) 1062 MIB.addReg(Regs[i], getDefRegState(true)); 1063 if (DeleteRet) { 1064 MIB.copyImplicitOps(&*MI); 1065 MI->eraseFromParent(); 1066 } 1067 MI = MIB; 1068 } else if (Regs.size() == 1) { 1069 // If we adjusted the reg to PC from LR above, switch it back here. We 1070 // only do that for LDM. 1071 if (Regs[0] == ARM::PC) 1072 Regs[0] = ARM::LR; 1073 MachineInstrBuilder MIB = 1074 BuildMI(MBB, MI, DL, TII.get(LdrOpc), Regs[0]) 1075 .addReg(ARM::SP, RegState::Define) 1076 .addReg(ARM::SP); 1077 // ARM mode needs an extra reg0 here due to addrmode2. Will go away once 1078 // that refactoring is complete (eventually). 1079 if (LdrOpc == ARM::LDR_POST_REG || LdrOpc == ARM::LDR_POST_IMM) { 1080 MIB.addReg(0); 1081 MIB.addImm(ARM_AM::getAM2Opc(ARM_AM::add, 4, ARM_AM::no_shift)); 1082 } else 1083 MIB.addImm(4); 1084 AddDefaultPred(MIB); 1085 } 1086 Regs.clear(); 1087 1088 // Put any subsequent vpop instructions after this one: they will refer to 1089 // higher register numbers so need to be popped afterwards. 1090 ++MI; 1091 } 1092 } 1093 1094 /// Emit aligned spill instructions for NumAlignedDPRCS2Regs D-registers 1095 /// starting from d8. Also insert stack realignment code and leave the stack 1096 /// pointer pointing to the d8 spill slot. 1097 static void emitAlignedDPRCS2Spills(MachineBasicBlock &MBB, 1098 MachineBasicBlock::iterator MI, 1099 unsigned NumAlignedDPRCS2Regs, 1100 const std::vector<CalleeSavedInfo> &CSI, 1101 const TargetRegisterInfo *TRI) { 1102 MachineFunction &MF = *MBB.getParent(); 1103 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>(); 1104 DebugLoc DL = MI->getDebugLoc(); 1105 const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); 1106 MachineFrameInfo &MFI = *MF.getFrameInfo(); 1107 1108 // Mark the D-register spill slots as properly aligned. Since MFI computes 1109 // stack slot layout backwards, this can actually mean that the d-reg stack 1110 // slot offsets can be wrong. The offset for d8 will always be correct. 1111 for (unsigned i = 0, e = CSI.size(); i != e; ++i) { 1112 unsigned DNum = CSI[i].getReg() - ARM::D8; 1113 if (DNum >= 8) 1114 continue; 1115 int FI = CSI[i].getFrameIdx(); 1116 // The even-numbered registers will be 16-byte aligned, the odd-numbered 1117 // registers will be 8-byte aligned. 1118 MFI.setObjectAlignment(FI, DNum % 2 ? 8 : 16); 1119 1120 // The stack slot for D8 needs to be maximally aligned because this is 1121 // actually the point where we align the stack pointer. MachineFrameInfo 1122 // computes all offsets relative to the incoming stack pointer which is a 1123 // bit weird when realigning the stack. Any extra padding for this 1124 // over-alignment is not realized because the code inserted below adjusts 1125 // the stack pointer by numregs * 8 before aligning the stack pointer. 1126 if (DNum == 0) 1127 MFI.setObjectAlignment(FI, MFI.getMaxAlignment()); 1128 } 1129 1130 // Move the stack pointer to the d8 spill slot, and align it at the same 1131 // time. Leave the stack slot address in the scratch register r4. 1132 // 1133 // sub r4, sp, #numregs * 8 1134 // bic r4, r4, #align - 1 1135 // mov sp, r4 1136 // 1137 bool isThumb = AFI->isThumbFunction(); 1138 assert(!AFI->isThumb1OnlyFunction() && "Can't realign stack for thumb1"); 1139 AFI->setShouldRestoreSPFromFP(true); 1140 1141 // sub r4, sp, #numregs * 8 1142 // The immediate is <= 64, so it doesn't need any special encoding. 1143 unsigned Opc = isThumb ? ARM::t2SUBri : ARM::SUBri; 1144 AddDefaultCC(AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(Opc), ARM::R4) 1145 .addReg(ARM::SP) 1146 .addImm(8 * NumAlignedDPRCS2Regs))); 1147 1148 unsigned MaxAlign = MF.getFrameInfo()->getMaxAlignment(); 1149 // We must set parameter MustBeSingleInstruction to true, since 1150 // skipAlignedDPRCS2Spills expects exactly 3 instructions to perform 1151 // stack alignment. Luckily, this can always be done since all ARM 1152 // architecture versions that support Neon also support the BFC 1153 // instruction. 1154 emitAligningInstructions(MF, AFI, TII, MBB, MI, DL, ARM::R4, MaxAlign, true); 1155 1156 // mov sp, r4 1157 // The stack pointer must be adjusted before spilling anything, otherwise 1158 // the stack slots could be clobbered by an interrupt handler. 1159 // Leave r4 live, it is used below. 1160 Opc = isThumb ? ARM::tMOVr : ARM::MOVr; 1161 MachineInstrBuilder MIB = BuildMI(MBB, MI, DL, TII.get(Opc), ARM::SP) 1162 .addReg(ARM::R4); 1163 MIB = AddDefaultPred(MIB); 1164 if (!isThumb) 1165 AddDefaultCC(MIB); 1166 1167 // Now spill NumAlignedDPRCS2Regs registers starting from d8. 1168 // r4 holds the stack slot address. 1169 unsigned NextReg = ARM::D8; 1170 1171 // 16-byte aligned vst1.64 with 4 d-regs and address writeback. 1172 // The writeback is only needed when emitting two vst1.64 instructions. 1173 if (NumAlignedDPRCS2Regs >= 6) { 1174 unsigned SupReg = TRI->getMatchingSuperReg(NextReg, ARM::dsub_0, 1175 &ARM::QQPRRegClass); 1176 MBB.addLiveIn(SupReg); 1177 AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VST1d64Qwb_fixed), 1178 ARM::R4) 1179 .addReg(ARM::R4, RegState::Kill).addImm(16) 1180 .addReg(NextReg) 1181 .addReg(SupReg, RegState::ImplicitKill)); 1182 NextReg += 4; 1183 NumAlignedDPRCS2Regs -= 4; 1184 } 1185 1186 // We won't modify r4 beyond this point. It currently points to the next 1187 // register to be spilled. 1188 unsigned R4BaseReg = NextReg; 1189 1190 // 16-byte aligned vst1.64 with 4 d-regs, no writeback. 1191 if (NumAlignedDPRCS2Regs >= 4) { 1192 unsigned SupReg = TRI->getMatchingSuperReg(NextReg, ARM::dsub_0, 1193 &ARM::QQPRRegClass); 1194 MBB.addLiveIn(SupReg); 1195 AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VST1d64Q)) 1196 .addReg(ARM::R4).addImm(16).addReg(NextReg) 1197 .addReg(SupReg, RegState::ImplicitKill)); 1198 NextReg += 4; 1199 NumAlignedDPRCS2Regs -= 4; 1200 } 1201 1202 // 16-byte aligned vst1.64 with 2 d-regs. 1203 if (NumAlignedDPRCS2Regs >= 2) { 1204 unsigned SupReg = TRI->getMatchingSuperReg(NextReg, ARM::dsub_0, 1205 &ARM::QPRRegClass); 1206 MBB.addLiveIn(SupReg); 1207 AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VST1q64)) 1208 .addReg(ARM::R4).addImm(16).addReg(SupReg)); 1209 NextReg += 2; 1210 NumAlignedDPRCS2Regs -= 2; 1211 } 1212 1213 // Finally, use a vanilla vstr.64 for the odd last register. 1214 if (NumAlignedDPRCS2Regs) { 1215 MBB.addLiveIn(NextReg); 1216 // vstr.64 uses addrmode5 which has an offset scale of 4. 1217 AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VSTRD)) 1218 .addReg(NextReg) 1219 .addReg(ARM::R4).addImm((NextReg-R4BaseReg)*2)); 1220 } 1221 1222 // The last spill instruction inserted should kill the scratch register r4. 1223 std::prev(MI)->addRegisterKilled(ARM::R4, TRI); 1224 } 1225 1226 /// Skip past the code inserted by emitAlignedDPRCS2Spills, and return an 1227 /// iterator to the following instruction. 1228 static MachineBasicBlock::iterator 1229 skipAlignedDPRCS2Spills(MachineBasicBlock::iterator MI, 1230 unsigned NumAlignedDPRCS2Regs) { 1231 // sub r4, sp, #numregs * 8 1232 // bic r4, r4, #align - 1 1233 // mov sp, r4 1234 ++MI; ++MI; ++MI; 1235 assert(MI->mayStore() && "Expecting spill instruction"); 1236 1237 // These switches all fall through. 1238 switch(NumAlignedDPRCS2Regs) { 1239 case 7: 1240 ++MI; 1241 assert(MI->mayStore() && "Expecting spill instruction"); 1242 default: 1243 ++MI; 1244 assert(MI->mayStore() && "Expecting spill instruction"); 1245 case 1: 1246 case 2: 1247 case 4: 1248 assert(MI->killsRegister(ARM::R4) && "Missed kill flag"); 1249 ++MI; 1250 } 1251 return MI; 1252 } 1253 1254 /// Emit aligned reload instructions for NumAlignedDPRCS2Regs D-registers 1255 /// starting from d8. These instructions are assumed to execute while the 1256 /// stack is still aligned, unlike the code inserted by emitPopInst. 1257 static void emitAlignedDPRCS2Restores(MachineBasicBlock &MBB, 1258 MachineBasicBlock::iterator MI, 1259 unsigned NumAlignedDPRCS2Regs, 1260 const std::vector<CalleeSavedInfo> &CSI, 1261 const TargetRegisterInfo *TRI) { 1262 MachineFunction &MF = *MBB.getParent(); 1263 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>(); 1264 DebugLoc DL = MI->getDebugLoc(); 1265 const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo(); 1266 1267 // Find the frame index assigned to d8. 1268 int D8SpillFI = 0; 1269 for (unsigned i = 0, e = CSI.size(); i != e; ++i) 1270 if (CSI[i].getReg() == ARM::D8) { 1271 D8SpillFI = CSI[i].getFrameIdx(); 1272 break; 1273 } 1274 1275 // Materialize the address of the d8 spill slot into the scratch register r4. 1276 // This can be fairly complicated if the stack frame is large, so just use 1277 // the normal frame index elimination mechanism to do it. This code runs as 1278 // the initial part of the epilog where the stack and base pointers haven't 1279 // been changed yet. 1280 bool isThumb = AFI->isThumbFunction(); 1281 assert(!AFI->isThumb1OnlyFunction() && "Can't realign stack for thumb1"); 1282 1283 unsigned Opc = isThumb ? ARM::t2ADDri : ARM::ADDri; 1284 AddDefaultCC(AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(Opc), ARM::R4) 1285 .addFrameIndex(D8SpillFI).addImm(0))); 1286 1287 // Now restore NumAlignedDPRCS2Regs registers starting from d8. 1288 unsigned NextReg = ARM::D8; 1289 1290 // 16-byte aligned vld1.64 with 4 d-regs and writeback. 1291 if (NumAlignedDPRCS2Regs >= 6) { 1292 unsigned SupReg = TRI->getMatchingSuperReg(NextReg, ARM::dsub_0, 1293 &ARM::QQPRRegClass); 1294 AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VLD1d64Qwb_fixed), NextReg) 1295 .addReg(ARM::R4, RegState::Define) 1296 .addReg(ARM::R4, RegState::Kill).addImm(16) 1297 .addReg(SupReg, RegState::ImplicitDefine)); 1298 NextReg += 4; 1299 NumAlignedDPRCS2Regs -= 4; 1300 } 1301 1302 // We won't modify r4 beyond this point. It currently points to the next 1303 // register to be spilled. 1304 unsigned R4BaseReg = NextReg; 1305 1306 // 16-byte aligned vld1.64 with 4 d-regs, no writeback. 1307 if (NumAlignedDPRCS2Regs >= 4) { 1308 unsigned SupReg = TRI->getMatchingSuperReg(NextReg, ARM::dsub_0, 1309 &ARM::QQPRRegClass); 1310 AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VLD1d64Q), NextReg) 1311 .addReg(ARM::R4).addImm(16) 1312 .addReg(SupReg, RegState::ImplicitDefine)); 1313 NextReg += 4; 1314 NumAlignedDPRCS2Regs -= 4; 1315 } 1316 1317 // 16-byte aligned vld1.64 with 2 d-regs. 1318 if (NumAlignedDPRCS2Regs >= 2) { 1319 unsigned SupReg = TRI->getMatchingSuperReg(NextReg, ARM::dsub_0, 1320 &ARM::QPRRegClass); 1321 AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VLD1q64), SupReg) 1322 .addReg(ARM::R4).addImm(16)); 1323 NextReg += 2; 1324 NumAlignedDPRCS2Regs -= 2; 1325 } 1326 1327 // Finally, use a vanilla vldr.64 for the remaining odd register. 1328 if (NumAlignedDPRCS2Regs) 1329 AddDefaultPred(BuildMI(MBB, MI, DL, TII.get(ARM::VLDRD), NextReg) 1330 .addReg(ARM::R4).addImm(2*(NextReg-R4BaseReg))); 1331 1332 // Last store kills r4. 1333 std::prev(MI)->addRegisterKilled(ARM::R4, TRI); 1334 } 1335 1336 bool ARMFrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB, 1337 MachineBasicBlock::iterator MI, 1338 const std::vector<CalleeSavedInfo> &CSI, 1339 const TargetRegisterInfo *TRI) const { 1340 if (CSI.empty()) 1341 return false; 1342 1343 MachineFunction &MF = *MBB.getParent(); 1344 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>(); 1345 1346 unsigned PushOpc = AFI->isThumbFunction() ? ARM::t2STMDB_UPD : ARM::STMDB_UPD; 1347 unsigned PushOneOpc = AFI->isThumbFunction() ? 1348 ARM::t2STR_PRE : ARM::STR_PRE_IMM; 1349 unsigned FltOpc = ARM::VSTMDDB_UPD; 1350 unsigned NumAlignedDPRCS2Regs = AFI->getNumAlignedDPRCS2Regs(); 1351 emitPushInst(MBB, MI, CSI, PushOpc, PushOneOpc, false, &isARMArea1Register, 0, 1352 MachineInstr::FrameSetup); 1353 emitPushInst(MBB, MI, CSI, PushOpc, PushOneOpc, false, &isARMArea2Register, 0, 1354 MachineInstr::FrameSetup); 1355 emitPushInst(MBB, MI, CSI, FltOpc, 0, true, &isARMArea3Register, 1356 NumAlignedDPRCS2Regs, MachineInstr::FrameSetup); 1357 1358 // The code above does not insert spill code for the aligned DPRCS2 registers. 1359 // The stack realignment code will be inserted between the push instructions 1360 // and these spills. 1361 if (NumAlignedDPRCS2Regs) 1362 emitAlignedDPRCS2Spills(MBB, MI, NumAlignedDPRCS2Regs, CSI, TRI); 1363 1364 return true; 1365 } 1366 1367 bool ARMFrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB, 1368 MachineBasicBlock::iterator MI, 1369 const std::vector<CalleeSavedInfo> &CSI, 1370 const TargetRegisterInfo *TRI) const { 1371 if (CSI.empty()) 1372 return false; 1373 1374 MachineFunction &MF = *MBB.getParent(); 1375 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>(); 1376 bool isVarArg = AFI->getArgRegsSaveSize() > 0; 1377 unsigned NumAlignedDPRCS2Regs = AFI->getNumAlignedDPRCS2Regs(); 1378 1379 // The emitPopInst calls below do not insert reloads for the aligned DPRCS2 1380 // registers. Do that here instead. 1381 if (NumAlignedDPRCS2Regs) 1382 emitAlignedDPRCS2Restores(MBB, MI, NumAlignedDPRCS2Regs, CSI, TRI); 1383 1384 unsigned PopOpc = AFI->isThumbFunction() ? ARM::t2LDMIA_UPD : ARM::LDMIA_UPD; 1385 unsigned LdrOpc = AFI->isThumbFunction() ? ARM::t2LDR_POST :ARM::LDR_POST_IMM; 1386 unsigned FltOpc = ARM::VLDMDIA_UPD; 1387 emitPopInst(MBB, MI, CSI, FltOpc, 0, isVarArg, true, &isARMArea3Register, 1388 NumAlignedDPRCS2Regs); 1389 emitPopInst(MBB, MI, CSI, PopOpc, LdrOpc, isVarArg, false, 1390 &isARMArea2Register, 0); 1391 emitPopInst(MBB, MI, CSI, PopOpc, LdrOpc, isVarArg, false, 1392 &isARMArea1Register, 0); 1393 1394 return true; 1395 } 1396 1397 // FIXME: Make generic? 1398 static unsigned GetFunctionSizeInBytes(const MachineFunction &MF, 1399 const ARMBaseInstrInfo &TII) { 1400 unsigned FnSize = 0; 1401 for (auto &MBB : MF) { 1402 for (auto &MI : MBB) 1403 FnSize += TII.GetInstSizeInBytes(&MI); 1404 } 1405 return FnSize; 1406 } 1407 1408 /// estimateRSStackSizeLimit - Look at each instruction that references stack 1409 /// frames and return the stack size limit beyond which some of these 1410 /// instructions will require a scratch register during their expansion later. 1411 // FIXME: Move to TII? 1412 static unsigned estimateRSStackSizeLimit(MachineFunction &MF, 1413 const TargetFrameLowering *TFI) { 1414 const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>(); 1415 unsigned Limit = (1 << 12) - 1; 1416 for (auto &MBB : MF) { 1417 for (auto &MI : MBB) { 1418 for (unsigned i = 0, e = MI.getNumOperands(); i != e; ++i) { 1419 if (!MI.getOperand(i).isFI()) 1420 continue; 1421 1422 // When using ADDri to get the address of a stack object, 255 is the 1423 // largest offset guaranteed to fit in the immediate offset. 1424 if (MI.getOpcode() == ARM::ADDri) { 1425 Limit = std::min(Limit, (1U << 8) - 1); 1426 break; 1427 } 1428 1429 // Otherwise check the addressing mode. 1430 switch (MI.getDesc().TSFlags & ARMII::AddrModeMask) { 1431 case ARMII::AddrMode3: 1432 case ARMII::AddrModeT2_i8: 1433 Limit = std::min(Limit, (1U << 8) - 1); 1434 break; 1435 case ARMII::AddrMode5: 1436 case ARMII::AddrModeT2_i8s4: 1437 Limit = std::min(Limit, ((1U << 8) - 1) * 4); 1438 break; 1439 case ARMII::AddrModeT2_i12: 1440 // i12 supports only positive offset so these will be converted to 1441 // i8 opcodes. See llvm::rewriteT2FrameIndex. 1442 if (TFI->hasFP(MF) && AFI->hasStackFrame()) 1443 Limit = std::min(Limit, (1U << 8) - 1); 1444 break; 1445 case ARMII::AddrMode4: 1446 case ARMII::AddrMode6: 1447 // Addressing modes 4 & 6 (load/store) instructions can't encode an 1448 // immediate offset for stack references. 1449 return 0; 1450 default: 1451 break; 1452 } 1453 break; // At most one FI per instruction 1454 } 1455 } 1456 } 1457 1458 return Limit; 1459 } 1460 1461 // In functions that realign the stack, it can be an advantage to spill the 1462 // callee-saved vector registers after realigning the stack. The vst1 and vld1 1463 // instructions take alignment hints that can improve performance. 1464 // 1465 static void checkNumAlignedDPRCS2Regs(MachineFunction &MF) { 1466 MF.getInfo<ARMFunctionInfo>()->setNumAlignedDPRCS2Regs(0); 1467 if (!SpillAlignedNEONRegs) 1468 return; 1469 1470 // Naked functions don't spill callee-saved registers. 1471 if (MF.getFunction()->hasFnAttribute(Attribute::Naked)) 1472 return; 1473 1474 // We are planning to use NEON instructions vst1 / vld1. 1475 if (!static_cast<const ARMSubtarget &>(MF.getSubtarget()).hasNEON()) 1476 return; 1477 1478 // Don't bother if the default stack alignment is sufficiently high. 1479 if (MF.getSubtarget().getFrameLowering()->getStackAlignment() >= 8) 1480 return; 1481 1482 // Aligned spills require stack realignment. 1483 if (!static_cast<const ARMBaseRegisterInfo *>( 1484 MF.getSubtarget().getRegisterInfo())->canRealignStack(MF)) 1485 return; 1486 1487 // We always spill contiguous d-registers starting from d8. Count how many 1488 // needs spilling. The register allocator will almost always use the 1489 // callee-saved registers in order, but it can happen that there are holes in 1490 // the range. Registers above the hole will be spilled to the standard DPRCS 1491 // area. 1492 MachineRegisterInfo &MRI = MF.getRegInfo(); 1493 unsigned NumSpills = 0; 1494 for (; NumSpills < 8; ++NumSpills) 1495 if (!MRI.isPhysRegUsed(ARM::D8 + NumSpills)) 1496 break; 1497 1498 // Don't do this for just one d-register. It's not worth it. 1499 if (NumSpills < 2) 1500 return; 1501 1502 // Spill the first NumSpills D-registers after realigning the stack. 1503 MF.getInfo<ARMFunctionInfo>()->setNumAlignedDPRCS2Regs(NumSpills); 1504 1505 // A scratch register is required for the vst1 / vld1 instructions. 1506 MF.getRegInfo().setPhysRegUsed(ARM::R4); 1507 } 1508 1509 void 1510 ARMFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF, 1511 RegScavenger *RS) const { 1512 // This tells PEI to spill the FP as if it is any other callee-save register 1513 // to take advantage the eliminateFrameIndex machinery. This also ensures it 1514 // is spilled in the order specified by getCalleeSavedRegs() to make it easier 1515 // to combine multiple loads / stores. 1516 bool CanEliminateFrame = true; 1517 bool CS1Spilled = false; 1518 bool LRSpilled = false; 1519 unsigned NumGPRSpills = 0; 1520 SmallVector<unsigned, 4> UnspilledCS1GPRs; 1521 SmallVector<unsigned, 4> UnspilledCS2GPRs; 1522 const ARMBaseRegisterInfo *RegInfo = static_cast<const ARMBaseRegisterInfo *>( 1523 MF.getSubtarget().getRegisterInfo()); 1524 const ARMBaseInstrInfo &TII = 1525 *static_cast<const ARMBaseInstrInfo *>(MF.getSubtarget().getInstrInfo()); 1526 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>(); 1527 MachineFrameInfo *MFI = MF.getFrameInfo(); 1528 MachineRegisterInfo &MRI = MF.getRegInfo(); 1529 unsigned FramePtr = RegInfo->getFrameRegister(MF); 1530 1531 // Spill R4 if Thumb2 function requires stack realignment - it will be used as 1532 // scratch register. Also spill R4 if Thumb2 function has varsized objects, 1533 // since it's not always possible to restore sp from fp in a single 1534 // instruction. 1535 // FIXME: It will be better just to find spare register here. 1536 if (AFI->isThumb2Function() && 1537 (MFI->hasVarSizedObjects() || RegInfo->needsStackRealignment(MF))) 1538 MRI.setPhysRegUsed(ARM::R4); 1539 1540 if (AFI->isThumb1OnlyFunction()) { 1541 // Spill LR if Thumb1 function uses variable length argument lists. 1542 if (AFI->getArgRegsSaveSize() > 0) 1543 MRI.setPhysRegUsed(ARM::LR); 1544 1545 // Spill R4 if Thumb1 epilogue has to restore SP from FP. We don't know 1546 // for sure what the stack size will be, but for this, an estimate is good 1547 // enough. If there anything changes it, it'll be a spill, which implies 1548 // we've used all the registers and so R4 is already used, so not marking 1549 // it here will be OK. 1550 // FIXME: It will be better just to find spare register here. 1551 unsigned StackSize = MFI->estimateStackSize(MF); 1552 if (MFI->hasVarSizedObjects() || StackSize > 508) 1553 MRI.setPhysRegUsed(ARM::R4); 1554 } 1555 1556 // See if we can spill vector registers to aligned stack. 1557 checkNumAlignedDPRCS2Regs(MF); 1558 1559 // Spill the BasePtr if it's used. 1560 if (RegInfo->hasBasePointer(MF)) 1561 MRI.setPhysRegUsed(RegInfo->getBaseRegister()); 1562 1563 // Don't spill FP if the frame can be eliminated. This is determined 1564 // by scanning the callee-save registers to see if any is used. 1565 const MCPhysReg *CSRegs = RegInfo->getCalleeSavedRegs(&MF); 1566 for (unsigned i = 0; CSRegs[i]; ++i) { 1567 unsigned Reg = CSRegs[i]; 1568 bool Spilled = false; 1569 if (MRI.isPhysRegUsed(Reg)) { 1570 Spilled = true; 1571 CanEliminateFrame = false; 1572 } 1573 1574 if (!ARM::GPRRegClass.contains(Reg)) 1575 continue; 1576 1577 if (Spilled) { 1578 NumGPRSpills++; 1579 1580 if (!STI.isTargetDarwin()) { 1581 if (Reg == ARM::LR) 1582 LRSpilled = true; 1583 CS1Spilled = true; 1584 continue; 1585 } 1586 1587 // Keep track if LR and any of R4, R5, R6, and R7 is spilled. 1588 switch (Reg) { 1589 case ARM::LR: 1590 LRSpilled = true; 1591 // Fallthrough 1592 case ARM::R0: case ARM::R1: 1593 case ARM::R2: case ARM::R3: 1594 case ARM::R4: case ARM::R5: 1595 case ARM::R6: case ARM::R7: 1596 CS1Spilled = true; 1597 break; 1598 default: 1599 break; 1600 } 1601 } else { 1602 if (!STI.isTargetDarwin()) { 1603 UnspilledCS1GPRs.push_back(Reg); 1604 continue; 1605 } 1606 1607 switch (Reg) { 1608 case ARM::R0: case ARM::R1: 1609 case ARM::R2: case ARM::R3: 1610 case ARM::R4: case ARM::R5: 1611 case ARM::R6: case ARM::R7: 1612 case ARM::LR: 1613 UnspilledCS1GPRs.push_back(Reg); 1614 break; 1615 default: 1616 UnspilledCS2GPRs.push_back(Reg); 1617 break; 1618 } 1619 } 1620 } 1621 1622 bool ForceLRSpill = false; 1623 if (!LRSpilled && AFI->isThumb1OnlyFunction()) { 1624 unsigned FnSize = GetFunctionSizeInBytes(MF, TII); 1625 // Force LR to be spilled if the Thumb function size is > 2048. This enables 1626 // use of BL to implement far jump. If it turns out that it's not needed 1627 // then the branch fix up path will undo it. 1628 if (FnSize >= (1 << 11)) { 1629 CanEliminateFrame = false; 1630 ForceLRSpill = true; 1631 } 1632 } 1633 1634 // If any of the stack slot references may be out of range of an immediate 1635 // offset, make sure a register (or a spill slot) is available for the 1636 // register scavenger. Note that if we're indexing off the frame pointer, the 1637 // effective stack size is 4 bytes larger since the FP points to the stack 1638 // slot of the previous FP. Also, if we have variable sized objects in the 1639 // function, stack slot references will often be negative, and some of 1640 // our instructions are positive-offset only, so conservatively consider 1641 // that case to want a spill slot (or register) as well. Similarly, if 1642 // the function adjusts the stack pointer during execution and the 1643 // adjustments aren't already part of our stack size estimate, our offset 1644 // calculations may be off, so be conservative. 1645 // FIXME: We could add logic to be more precise about negative offsets 1646 // and which instructions will need a scratch register for them. Is it 1647 // worth the effort and added fragility? 1648 bool BigStack = 1649 (RS && 1650 (MFI->estimateStackSize(MF) + 1651 ((hasFP(MF) && AFI->hasStackFrame()) ? 4:0) >= 1652 estimateRSStackSizeLimit(MF, this))) 1653 || MFI->hasVarSizedObjects() 1654 || (MFI->adjustsStack() && !canSimplifyCallFramePseudos(MF)); 1655 1656 bool ExtraCSSpill = false; 1657 if (BigStack || !CanEliminateFrame || RegInfo->cannotEliminateFrame(MF)) { 1658 AFI->setHasStackFrame(true); 1659 1660 // If LR is not spilled, but at least one of R4, R5, R6, and R7 is spilled. 1661 // Spill LR as well so we can fold BX_RET to the registers restore (LDM). 1662 if (!LRSpilled && CS1Spilled) { 1663 MRI.setPhysRegUsed(ARM::LR); 1664 NumGPRSpills++; 1665 SmallVectorImpl<unsigned>::iterator LRPos; 1666 LRPos = std::find(UnspilledCS1GPRs.begin(), UnspilledCS1GPRs.end(), 1667 (unsigned)ARM::LR); 1668 if (LRPos != UnspilledCS1GPRs.end()) 1669 UnspilledCS1GPRs.erase(LRPos); 1670 1671 ForceLRSpill = false; 1672 ExtraCSSpill = true; 1673 } 1674 1675 if (hasFP(MF)) { 1676 MRI.setPhysRegUsed(FramePtr); 1677 auto FPPos = std::find(UnspilledCS1GPRs.begin(), UnspilledCS1GPRs.end(), 1678 FramePtr); 1679 if (FPPos != UnspilledCS1GPRs.end()) 1680 UnspilledCS1GPRs.erase(FPPos); 1681 NumGPRSpills++; 1682 } 1683 1684 // If stack and double are 8-byte aligned and we are spilling an odd number 1685 // of GPRs, spill one extra callee save GPR so we won't have to pad between 1686 // the integer and double callee save areas. 1687 unsigned TargetAlign = getStackAlignment(); 1688 if (TargetAlign >= 8 && (NumGPRSpills & 1)) { 1689 if (CS1Spilled && !UnspilledCS1GPRs.empty()) { 1690 for (unsigned i = 0, e = UnspilledCS1GPRs.size(); i != e; ++i) { 1691 unsigned Reg = UnspilledCS1GPRs[i]; 1692 // Don't spill high register if the function is thumb 1693 if (!AFI->isThumbFunction() || 1694 isARMLowRegister(Reg) || Reg == ARM::LR) { 1695 MRI.setPhysRegUsed(Reg); 1696 if (!MRI.isReserved(Reg)) 1697 ExtraCSSpill = true; 1698 break; 1699 } 1700 } 1701 } else if (!UnspilledCS2GPRs.empty() && !AFI->isThumb1OnlyFunction()) { 1702 unsigned Reg = UnspilledCS2GPRs.front(); 1703 MRI.setPhysRegUsed(Reg); 1704 if (!MRI.isReserved(Reg)) 1705 ExtraCSSpill = true; 1706 } 1707 } 1708 1709 // Estimate if we might need to scavenge a register at some point in order 1710 // to materialize a stack offset. If so, either spill one additional 1711 // callee-saved register or reserve a special spill slot to facilitate 1712 // register scavenging. Thumb1 needs a spill slot for stack pointer 1713 // adjustments also, even when the frame itself is small. 1714 if (BigStack && !ExtraCSSpill) { 1715 // If any non-reserved CS register isn't spilled, just spill one or two 1716 // extra. That should take care of it! 1717 unsigned NumExtras = TargetAlign / 4; 1718 SmallVector<unsigned, 2> Extras; 1719 while (NumExtras && !UnspilledCS1GPRs.empty()) { 1720 unsigned Reg = UnspilledCS1GPRs.back(); 1721 UnspilledCS1GPRs.pop_back(); 1722 if (!MRI.isReserved(Reg) && 1723 (!AFI->isThumb1OnlyFunction() || isARMLowRegister(Reg) || 1724 Reg == ARM::LR)) { 1725 Extras.push_back(Reg); 1726 NumExtras--; 1727 } 1728 } 1729 // For non-Thumb1 functions, also check for hi-reg CS registers 1730 if (!AFI->isThumb1OnlyFunction()) { 1731 while (NumExtras && !UnspilledCS2GPRs.empty()) { 1732 unsigned Reg = UnspilledCS2GPRs.back(); 1733 UnspilledCS2GPRs.pop_back(); 1734 if (!MRI.isReserved(Reg)) { 1735 Extras.push_back(Reg); 1736 NumExtras--; 1737 } 1738 } 1739 } 1740 if (Extras.size() && NumExtras == 0) { 1741 for (unsigned i = 0, e = Extras.size(); i != e; ++i) { 1742 MRI.setPhysRegUsed(Extras[i]); 1743 } 1744 } else if (!AFI->isThumb1OnlyFunction()) { 1745 // note: Thumb1 functions spill to R12, not the stack. Reserve a slot 1746 // closest to SP or frame pointer. 1747 const TargetRegisterClass *RC = &ARM::GPRRegClass; 1748 RS->addScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(), 1749 RC->getAlignment(), 1750 false)); 1751 } 1752 } 1753 } 1754 1755 if (ForceLRSpill) { 1756 MRI.setPhysRegUsed(ARM::LR); 1757 AFI->setLRIsSpilledForFarJump(true); 1758 } 1759 } 1760 1761 1762 void ARMFrameLowering:: 1763 eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB, 1764 MachineBasicBlock::iterator I) const { 1765 const ARMBaseInstrInfo &TII = 1766 *static_cast<const ARMBaseInstrInfo *>(MF.getSubtarget().getInstrInfo()); 1767 if (!hasReservedCallFrame(MF)) { 1768 // If we have alloca, convert as follows: 1769 // ADJCALLSTACKDOWN -> sub, sp, sp, amount 1770 // ADJCALLSTACKUP -> add, sp, sp, amount 1771 MachineInstr *Old = I; 1772 DebugLoc dl = Old->getDebugLoc(); 1773 unsigned Amount = Old->getOperand(0).getImm(); 1774 if (Amount != 0) { 1775 // We need to keep the stack aligned properly. To do this, we round the 1776 // amount of space needed for the outgoing arguments up to the next 1777 // alignment boundary. 1778 unsigned Align = getStackAlignment(); 1779 Amount = (Amount+Align-1)/Align*Align; 1780 1781 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>(); 1782 assert(!AFI->isThumb1OnlyFunction() && 1783 "This eliminateCallFramePseudoInstr does not support Thumb1!"); 1784 bool isARM = !AFI->isThumbFunction(); 1785 1786 // Replace the pseudo instruction with a new instruction... 1787 unsigned Opc = Old->getOpcode(); 1788 int PIdx = Old->findFirstPredOperandIdx(); 1789 ARMCC::CondCodes Pred = (PIdx == -1) 1790 ? ARMCC::AL : (ARMCC::CondCodes)Old->getOperand(PIdx).getImm(); 1791 if (Opc == ARM::ADJCALLSTACKDOWN || Opc == ARM::tADJCALLSTACKDOWN) { 1792 // Note: PredReg is operand 2 for ADJCALLSTACKDOWN. 1793 unsigned PredReg = Old->getOperand(2).getReg(); 1794 emitSPUpdate(isARM, MBB, I, dl, TII, -Amount, MachineInstr::NoFlags, 1795 Pred, PredReg); 1796 } else { 1797 // Note: PredReg is operand 3 for ADJCALLSTACKUP. 1798 unsigned PredReg = Old->getOperand(3).getReg(); 1799 assert(Opc == ARM::ADJCALLSTACKUP || Opc == ARM::tADJCALLSTACKUP); 1800 emitSPUpdate(isARM, MBB, I, dl, TII, Amount, MachineInstr::NoFlags, 1801 Pred, PredReg); 1802 } 1803 } 1804 } 1805 MBB.erase(I); 1806 } 1807 1808 /// Get the minimum constant for ARM that is greater than or equal to the 1809 /// argument. In ARM, constants can have any value that can be produced by 1810 /// rotating an 8-bit value to the right by an even number of bits within a 1811 /// 32-bit word. 1812 static uint32_t alignToARMConstant(uint32_t Value) { 1813 unsigned Shifted = 0; 1814 1815 if (Value == 0) 1816 return 0; 1817 1818 while (!(Value & 0xC0000000)) { 1819 Value = Value << 2; 1820 Shifted += 2; 1821 } 1822 1823 bool Carry = (Value & 0x00FFFFFF); 1824 Value = ((Value & 0xFF000000) >> 24) + Carry; 1825 1826 if (Value & 0x0000100) 1827 Value = Value & 0x000001FC; 1828 1829 if (Shifted > 24) 1830 Value = Value >> (Shifted - 24); 1831 else 1832 Value = Value << (24 - Shifted); 1833 1834 return Value; 1835 } 1836 1837 // The stack limit in the TCB is set to this many bytes above the actual 1838 // stack limit. 1839 static const uint64_t kSplitStackAvailable = 256; 1840 1841 // Adjust the function prologue to enable split stacks. This currently only 1842 // supports android and linux. 1843 // 1844 // The ABI of the segmented stack prologue is a little arbitrarily chosen, but 1845 // must be well defined in order to allow for consistent implementations of the 1846 // __morestack helper function. The ABI is also not a normal ABI in that it 1847 // doesn't follow the normal calling conventions because this allows the 1848 // prologue of each function to be optimized further. 1849 // 1850 // Currently, the ABI looks like (when calling __morestack) 1851 // 1852 // * r4 holds the minimum stack size requested for this function call 1853 // * r5 holds the stack size of the arguments to the function 1854 // * the beginning of the function is 3 instructions after the call to 1855 // __morestack 1856 // 1857 // Implementations of __morestack should use r4 to allocate a new stack, r5 to 1858 // place the arguments on to the new stack, and the 3-instruction knowledge to 1859 // jump directly to the body of the function when working on the new stack. 1860 // 1861 // An old (and possibly no longer compatible) implementation of __morestack for 1862 // ARM can be found at [1]. 1863 // 1864 // [1] - https://github.com/mozilla/rust/blob/86efd9/src/rt/arch/arm/morestack.S 1865 void ARMFrameLowering::adjustForSegmentedStacks( 1866 MachineFunction &MF, MachineBasicBlock &PrologueMBB) const { 1867 unsigned Opcode; 1868 unsigned CFIIndex; 1869 const ARMSubtarget *ST = &MF.getSubtarget<ARMSubtarget>(); 1870 bool Thumb = ST->isThumb(); 1871 1872 // Sadly, this currently doesn't support varargs, platforms other than 1873 // android/linux. Note that thumb1/thumb2 are support for android/linux. 1874 if (MF.getFunction()->isVarArg()) 1875 report_fatal_error("Segmented stacks do not support vararg functions."); 1876 if (!ST->isTargetAndroid() && !ST->isTargetLinux()) 1877 report_fatal_error("Segmented stacks not supported on this platform."); 1878 1879 assert(&PrologueMBB == &MF.front() && "Shrink-wrapping not yet implemented"); 1880 MachineFrameInfo *MFI = MF.getFrameInfo(); 1881 MachineModuleInfo &MMI = MF.getMMI(); 1882 MCContext &Context = MMI.getContext(); 1883 const MCRegisterInfo *MRI = Context.getRegisterInfo(); 1884 const ARMBaseInstrInfo &TII = 1885 *static_cast<const ARMBaseInstrInfo *>(MF.getSubtarget().getInstrInfo()); 1886 ARMFunctionInfo *ARMFI = MF.getInfo<ARMFunctionInfo>(); 1887 DebugLoc DL; 1888 1889 uint64_t StackSize = MFI->getStackSize(); 1890 1891 // Do not generate a prologue for functions with a stack of size zero 1892 if (StackSize == 0) 1893 return; 1894 1895 // Use R4 and R5 as scratch registers. 1896 // We save R4 and R5 before use and restore them before leaving the function. 1897 unsigned ScratchReg0 = ARM::R4; 1898 unsigned ScratchReg1 = ARM::R5; 1899 uint64_t AlignedStackSize; 1900 1901 MachineBasicBlock *PrevStackMBB = MF.CreateMachineBasicBlock(); 1902 MachineBasicBlock *PostStackMBB = MF.CreateMachineBasicBlock(); 1903 MachineBasicBlock *AllocMBB = MF.CreateMachineBasicBlock(); 1904 MachineBasicBlock *GetMBB = MF.CreateMachineBasicBlock(); 1905 MachineBasicBlock *McrMBB = MF.CreateMachineBasicBlock(); 1906 1907 for (MachineBasicBlock::livein_iterator i = PrologueMBB.livein_begin(), 1908 e = PrologueMBB.livein_end(); 1909 i != e; ++i) { 1910 AllocMBB->addLiveIn(*i); 1911 GetMBB->addLiveIn(*i); 1912 McrMBB->addLiveIn(*i); 1913 PrevStackMBB->addLiveIn(*i); 1914 PostStackMBB->addLiveIn(*i); 1915 } 1916 1917 MF.push_front(PostStackMBB); 1918 MF.push_front(AllocMBB); 1919 MF.push_front(GetMBB); 1920 MF.push_front(McrMBB); 1921 MF.push_front(PrevStackMBB); 1922 1923 // The required stack size that is aligned to ARM constant criterion. 1924 AlignedStackSize = alignToARMConstant(StackSize); 1925 1926 // When the frame size is less than 256 we just compare the stack 1927 // boundary directly to the value of the stack pointer, per gcc. 1928 bool CompareStackPointer = AlignedStackSize < kSplitStackAvailable; 1929 1930 // We will use two of the callee save registers as scratch registers so we 1931 // need to save those registers onto the stack. 1932 // We will use SR0 to hold stack limit and SR1 to hold the stack size 1933 // requested and arguments for __morestack(). 1934 // SR0: Scratch Register #0 1935 // SR1: Scratch Register #1 1936 // push {SR0, SR1} 1937 if (Thumb) { 1938 AddDefaultPred(BuildMI(PrevStackMBB, DL, TII.get(ARM::tPUSH))) 1939 .addReg(ScratchReg0).addReg(ScratchReg1); 1940 } else { 1941 AddDefaultPred(BuildMI(PrevStackMBB, DL, TII.get(ARM::STMDB_UPD)) 1942 .addReg(ARM::SP, RegState::Define).addReg(ARM::SP)) 1943 .addReg(ScratchReg0).addReg(ScratchReg1); 1944 } 1945 1946 // Emit the relevant DWARF information about the change in stack pointer as 1947 // well as where to find both r4 and r5 (the callee-save registers) 1948 CFIIndex = 1949 MMI.addFrameInst(MCCFIInstruction::createDefCfaOffset(nullptr, -8)); 1950 BuildMI(PrevStackMBB, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) 1951 .addCFIIndex(CFIIndex); 1952 CFIIndex = MMI.addFrameInst(MCCFIInstruction::createOffset( 1953 nullptr, MRI->getDwarfRegNum(ScratchReg1, true), -4)); 1954 BuildMI(PrevStackMBB, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) 1955 .addCFIIndex(CFIIndex); 1956 CFIIndex = MMI.addFrameInst(MCCFIInstruction::createOffset( 1957 nullptr, MRI->getDwarfRegNum(ScratchReg0, true), -8)); 1958 BuildMI(PrevStackMBB, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) 1959 .addCFIIndex(CFIIndex); 1960 1961 // mov SR1, sp 1962 if (Thumb) { 1963 AddDefaultPred(BuildMI(McrMBB, DL, TII.get(ARM::tMOVr), ScratchReg1) 1964 .addReg(ARM::SP)); 1965 } else if (CompareStackPointer) { 1966 AddDefaultPred(BuildMI(McrMBB, DL, TII.get(ARM::MOVr), ScratchReg1) 1967 .addReg(ARM::SP)).addReg(0); 1968 } 1969 1970 // sub SR1, sp, #StackSize 1971 if (!CompareStackPointer && Thumb) { 1972 AddDefaultPred( 1973 AddDefaultCC(BuildMI(McrMBB, DL, TII.get(ARM::tSUBi8), ScratchReg1)) 1974 .addReg(ScratchReg1).addImm(AlignedStackSize)); 1975 } else if (!CompareStackPointer) { 1976 AddDefaultPred(BuildMI(McrMBB, DL, TII.get(ARM::SUBri), ScratchReg1) 1977 .addReg(ARM::SP).addImm(AlignedStackSize)).addReg(0); 1978 } 1979 1980 if (Thumb && ST->isThumb1Only()) { 1981 unsigned PCLabelId = ARMFI->createPICLabelUId(); 1982 ARMConstantPoolValue *NewCPV = ARMConstantPoolSymbol::Create( 1983 MF.getFunction()->getContext(), "__STACK_LIMIT", PCLabelId, 0); 1984 MachineConstantPool *MCP = MF.getConstantPool(); 1985 unsigned CPI = MCP->getConstantPoolIndex(NewCPV, MF.getAlignment()); 1986 1987 // ldr SR0, [pc, offset(STACK_LIMIT)] 1988 AddDefaultPred(BuildMI(GetMBB, DL, TII.get(ARM::tLDRpci), ScratchReg0) 1989 .addConstantPoolIndex(CPI)); 1990 1991 // ldr SR0, [SR0] 1992 AddDefaultPred(BuildMI(GetMBB, DL, TII.get(ARM::tLDRi), ScratchReg0) 1993 .addReg(ScratchReg0).addImm(0)); 1994 } else { 1995 // Get TLS base address from the coprocessor 1996 // mrc p15, #0, SR0, c13, c0, #3 1997 AddDefaultPred(BuildMI(McrMBB, DL, TII.get(ARM::MRC), ScratchReg0) 1998 .addImm(15) 1999 .addImm(0) 2000 .addImm(13) 2001 .addImm(0) 2002 .addImm(3)); 2003 2004 // Use the last tls slot on android and a private field of the TCP on linux. 2005 assert(ST->isTargetAndroid() || ST->isTargetLinux()); 2006 unsigned TlsOffset = ST->isTargetAndroid() ? 63 : 1; 2007 2008 // Get the stack limit from the right offset 2009 // ldr SR0, [sr0, #4 * TlsOffset] 2010 AddDefaultPred(BuildMI(GetMBB, DL, TII.get(ARM::LDRi12), ScratchReg0) 2011 .addReg(ScratchReg0).addImm(4 * TlsOffset)); 2012 } 2013 2014 // Compare stack limit with stack size requested. 2015 // cmp SR0, SR1 2016 Opcode = Thumb ? ARM::tCMPr : ARM::CMPrr; 2017 AddDefaultPred(BuildMI(GetMBB, DL, TII.get(Opcode)) 2018 .addReg(ScratchReg0) 2019 .addReg(ScratchReg1)); 2020 2021 // This jump is taken if StackLimit < SP - stack required. 2022 Opcode = Thumb ? ARM::tBcc : ARM::Bcc; 2023 BuildMI(GetMBB, DL, TII.get(Opcode)).addMBB(PostStackMBB) 2024 .addImm(ARMCC::LO) 2025 .addReg(ARM::CPSR); 2026 2027 2028 // Calling __morestack(StackSize, Size of stack arguments). 2029 // __morestack knows that the stack size requested is in SR0(r4) 2030 // and amount size of stack arguments is in SR1(r5). 2031 2032 // Pass first argument for the __morestack by Scratch Register #0. 2033 // The amount size of stack required 2034 if (Thumb) { 2035 AddDefaultPred(AddDefaultCC(BuildMI(AllocMBB, DL, TII.get(ARM::tMOVi8), 2036 ScratchReg0)).addImm(AlignedStackSize)); 2037 } else { 2038 AddDefaultPred(BuildMI(AllocMBB, DL, TII.get(ARM::MOVi), ScratchReg0) 2039 .addImm(AlignedStackSize)).addReg(0); 2040 } 2041 // Pass second argument for the __morestack by Scratch Register #1. 2042 // The amount size of stack consumed to save function arguments. 2043 if (Thumb) { 2044 AddDefaultPred( 2045 AddDefaultCC(BuildMI(AllocMBB, DL, TII.get(ARM::tMOVi8), ScratchReg1)) 2046 .addImm(alignToARMConstant(ARMFI->getArgumentStackSize()))); 2047 } else { 2048 AddDefaultPred(BuildMI(AllocMBB, DL, TII.get(ARM::MOVi), ScratchReg1) 2049 .addImm(alignToARMConstant(ARMFI->getArgumentStackSize()))) 2050 .addReg(0); 2051 } 2052 2053 // push {lr} - Save return address of this function. 2054 if (Thumb) { 2055 AddDefaultPred(BuildMI(AllocMBB, DL, TII.get(ARM::tPUSH))) 2056 .addReg(ARM::LR); 2057 } else { 2058 AddDefaultPred(BuildMI(AllocMBB, DL, TII.get(ARM::STMDB_UPD)) 2059 .addReg(ARM::SP, RegState::Define) 2060 .addReg(ARM::SP)) 2061 .addReg(ARM::LR); 2062 } 2063 2064 // Emit the DWARF info about the change in stack as well as where to find the 2065 // previous link register 2066 CFIIndex = 2067 MMI.addFrameInst(MCCFIInstruction::createDefCfaOffset(nullptr, -12)); 2068 BuildMI(AllocMBB, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) 2069 .addCFIIndex(CFIIndex); 2070 CFIIndex = MMI.addFrameInst(MCCFIInstruction::createOffset( 2071 nullptr, MRI->getDwarfRegNum(ARM::LR, true), -12)); 2072 BuildMI(AllocMBB, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) 2073 .addCFIIndex(CFIIndex); 2074 2075 // Call __morestack(). 2076 if (Thumb) { 2077 AddDefaultPred(BuildMI(AllocMBB, DL, TII.get(ARM::tBL))) 2078 .addExternalSymbol("__morestack"); 2079 } else { 2080 BuildMI(AllocMBB, DL, TII.get(ARM::BL)) 2081 .addExternalSymbol("__morestack"); 2082 } 2083 2084 // pop {lr} - Restore return address of this original function. 2085 if (Thumb) { 2086 if (ST->isThumb1Only()) { 2087 AddDefaultPred(BuildMI(AllocMBB, DL, TII.get(ARM::tPOP))) 2088 .addReg(ScratchReg0); 2089 AddDefaultPred(BuildMI(AllocMBB, DL, TII.get(ARM::tMOVr), ARM::LR) 2090 .addReg(ScratchReg0)); 2091 } else { 2092 AddDefaultPred(BuildMI(AllocMBB, DL, TII.get(ARM::t2LDR_POST)) 2093 .addReg(ARM::LR, RegState::Define) 2094 .addReg(ARM::SP, RegState::Define) 2095 .addReg(ARM::SP) 2096 .addImm(4)); 2097 } 2098 } else { 2099 AddDefaultPred(BuildMI(AllocMBB, DL, TII.get(ARM::LDMIA_UPD)) 2100 .addReg(ARM::SP, RegState::Define) 2101 .addReg(ARM::SP)) 2102 .addReg(ARM::LR); 2103 } 2104 2105 // Restore SR0 and SR1 in case of __morestack() was called. 2106 // __morestack() will skip PostStackMBB block so we need to restore 2107 // scratch registers from here. 2108 // pop {SR0, SR1} 2109 if (Thumb) { 2110 AddDefaultPred(BuildMI(AllocMBB, DL, TII.get(ARM::tPOP))) 2111 .addReg(ScratchReg0) 2112 .addReg(ScratchReg1); 2113 } else { 2114 AddDefaultPred(BuildMI(AllocMBB, DL, TII.get(ARM::LDMIA_UPD)) 2115 .addReg(ARM::SP, RegState::Define) 2116 .addReg(ARM::SP)) 2117 .addReg(ScratchReg0) 2118 .addReg(ScratchReg1); 2119 } 2120 2121 // Update the CFA offset now that we've popped 2122 CFIIndex = MMI.addFrameInst(MCCFIInstruction::createDefCfaOffset(nullptr, 0)); 2123 BuildMI(AllocMBB, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) 2124 .addCFIIndex(CFIIndex); 2125 2126 // bx lr - Return from this function. 2127 Opcode = Thumb ? ARM::tBX_RET : ARM::BX_RET; 2128 AddDefaultPred(BuildMI(AllocMBB, DL, TII.get(Opcode))); 2129 2130 // Restore SR0 and SR1 in case of __morestack() was not called. 2131 // pop {SR0, SR1} 2132 if (Thumb) { 2133 AddDefaultPred(BuildMI(PostStackMBB, DL, TII.get(ARM::tPOP))) 2134 .addReg(ScratchReg0) 2135 .addReg(ScratchReg1); 2136 } else { 2137 AddDefaultPred(BuildMI(PostStackMBB, DL, TII.get(ARM::LDMIA_UPD)) 2138 .addReg(ARM::SP, RegState::Define) 2139 .addReg(ARM::SP)) 2140 .addReg(ScratchReg0) 2141 .addReg(ScratchReg1); 2142 } 2143 2144 // Update the CFA offset now that we've popped 2145 CFIIndex = MMI.addFrameInst(MCCFIInstruction::createDefCfaOffset(nullptr, 0)); 2146 BuildMI(PostStackMBB, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) 2147 .addCFIIndex(CFIIndex); 2148 2149 // Tell debuggers that r4 and r5 are now the same as they were in the 2150 // previous function, that they're the "Same Value". 2151 CFIIndex = MMI.addFrameInst(MCCFIInstruction::createSameValue( 2152 nullptr, MRI->getDwarfRegNum(ScratchReg0, true))); 2153 BuildMI(PostStackMBB, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) 2154 .addCFIIndex(CFIIndex); 2155 CFIIndex = MMI.addFrameInst(MCCFIInstruction::createSameValue( 2156 nullptr, MRI->getDwarfRegNum(ScratchReg1, true))); 2157 BuildMI(PostStackMBB, DL, TII.get(TargetOpcode::CFI_INSTRUCTION)) 2158 .addCFIIndex(CFIIndex); 2159 2160 // Organizing MBB lists 2161 PostStackMBB->addSuccessor(&PrologueMBB); 2162 2163 AllocMBB->addSuccessor(PostStackMBB); 2164 2165 GetMBB->addSuccessor(PostStackMBB); 2166 GetMBB->addSuccessor(AllocMBB); 2167 2168 McrMBB->addSuccessor(GetMBB); 2169 2170 PrevStackMBB->addSuccessor(McrMBB); 2171 2172 #ifdef XDEBUG 2173 MF.verify(); 2174 #endif 2175 } 2176