1 //===-- ARMBaseRegisterInfo.cpp - ARM Register Information ----------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains the base ARM implementation of TargetRegisterInfo class.
12 //===----------------------------------------------------------------------===//
14 #include "ARMBaseRegisterInfo.h"
16 #include "ARMBaseInstrInfo.h"
17 #include "ARMFrameLowering.h"
18 #include "ARMMachineFunctionInfo.h"
19 #include "ARMSubtarget.h"
20 #include "MCTargetDesc/ARMAddressingModes.h"
21 #include "llvm/ADT/BitVector.h"
22 #include "llvm/ADT/SmallVector.h"
23 #include "llvm/CodeGen/MachineConstantPool.h"
24 #include "llvm/CodeGen/MachineFrameInfo.h"
25 #include "llvm/CodeGen/MachineFunction.h"
26 #include "llvm/CodeGen/MachineInstrBuilder.h"
27 #include "llvm/CodeGen/MachineRegisterInfo.h"
28 #include "llvm/CodeGen/RegisterScavenging.h"
29 #include "llvm/CodeGen/VirtRegMap.h"
30 #include "llvm/IR/Constants.h"
31 #include "llvm/IR/DerivedTypes.h"
32 #include "llvm/IR/Function.h"
33 #include "llvm/IR/LLVMContext.h"
34 #include "llvm/Support/Debug.h"
35 #include "llvm/Support/ErrorHandling.h"
36 #include "llvm/Support/raw_ostream.h"
37 #include "llvm/Target/TargetFrameLowering.h"
38 #include "llvm/Target/TargetMachine.h"
39 #include "llvm/Target/TargetOptions.h"
41 #define DEBUG_TYPE "arm-register-info"
43 #define GET_REGINFO_TARGET_DESC
44 #include "ARMGenRegisterInfo.inc"
48 ARMBaseRegisterInfo::ARMBaseRegisterInfo(const ARMSubtarget &sti)
49 : ARMGenRegisterInfo(ARM::LR, 0, 0, ARM::PC), STI(sti), BasePtr(ARM::R6) {
50 if (STI.isTargetMachO()) {
51 if (STI.isTargetDarwin() || STI.isThumb1Only())
55 } else if (STI.isTargetWindows())
58 FramePtr = STI.isThumb() ? ARM::R7 : ARM::R11;
62 ARMBaseRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
63 const MCPhysReg *RegList =
64 STI.isTargetDarwin() ? CSR_iOS_SaveList : CSR_AAPCS_SaveList;
66 if (!MF) return RegList;
68 const Function *F = MF->getFunction();
69 if (F->getCallingConv() == CallingConv::GHC) {
70 // GHC set of callee saved regs is empty as all those regs are
71 // used for passing STG regs around
72 return CSR_NoRegs_SaveList;
73 } else if (F->hasFnAttribute("interrupt")) {
75 // M-class CPUs have hardware which saves the registers needed to allow a
76 // function conforming to the AAPCS to function as a handler.
77 return CSR_AAPCS_SaveList;
78 } else if (F->getFnAttribute("interrupt").getValueAsString() == "FIQ") {
79 // Fast interrupt mode gives the handler a private copy of R8-R14, so less
80 // need to be saved to restore user-mode state.
81 return CSR_FIQ_SaveList;
83 // Generally only R13-R14 (i.e. SP, LR) are automatically preserved by
84 // exception handling.
85 return CSR_GenericInt_SaveList;
93 ARMBaseRegisterInfo::getCallPreservedMask(CallingConv::ID CC) const {
94 if (CC == CallingConv::GHC)
95 // This is academic becase all GHC calls are (supposed to be) tail calls
96 return CSR_NoRegs_RegMask;
97 return STI.isTargetDarwin() ? CSR_iOS_RegMask : CSR_AAPCS_RegMask;
101 ARMBaseRegisterInfo::getNoPreservedMask() const {
102 return CSR_NoRegs_RegMask;
106 ARMBaseRegisterInfo::getThisReturnPreservedMask(CallingConv::ID CC) const {
107 // This should return a register mask that is the same as that returned by
108 // getCallPreservedMask but that additionally preserves the register used for
109 // the first i32 argument (which must also be the register used to return a
110 // single i32 return value)
112 // In case that the calling convention does not use the same register for
113 // both or otherwise does not want to enable this optimization, the function
114 // should return NULL
115 if (CC == CallingConv::GHC)
116 // This is academic becase all GHC calls are (supposed to be) tail calls
118 return STI.isTargetDarwin() ? CSR_iOS_ThisReturn_RegMask
119 : CSR_AAPCS_ThisReturn_RegMask;
122 BitVector ARMBaseRegisterInfo::
123 getReservedRegs(const MachineFunction &MF) const {
124 const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
126 // FIXME: avoid re-calculating this every time.
127 BitVector Reserved(getNumRegs());
128 Reserved.set(ARM::SP);
129 Reserved.set(ARM::PC);
130 Reserved.set(ARM::FPSCR);
131 Reserved.set(ARM::APSR_NZCV);
133 Reserved.set(FramePtr);
134 if (hasBasePointer(MF))
135 Reserved.set(BasePtr);
136 // Some targets reserve R9.
137 if (STI.isR9Reserved())
138 Reserved.set(ARM::R9);
139 // Reserve D16-D31 if the subtarget doesn't support them.
140 if (!STI.hasVFP3() || STI.hasD16()) {
141 assert(ARM::D31 == ARM::D16 + 15);
142 for (unsigned i = 0; i != 16; ++i)
143 Reserved.set(ARM::D16 + i);
145 const TargetRegisterClass *RC = &ARM::GPRPairRegClass;
146 for(TargetRegisterClass::iterator I = RC->begin(), E = RC->end(); I!=E; ++I)
147 for (MCSubRegIterator SI(*I, this); SI.isValid(); ++SI)
148 if (Reserved.test(*SI)) Reserved.set(*I);
153 const TargetRegisterClass*
154 ARMBaseRegisterInfo::getLargestLegalSuperClass(const TargetRegisterClass *RC)
156 const TargetRegisterClass *Super = RC;
157 TargetRegisterClass::sc_iterator I = RC->getSuperClasses();
159 switch (Super->getID()) {
160 case ARM::GPRRegClassID:
161 case ARM::SPRRegClassID:
162 case ARM::DPRRegClassID:
163 case ARM::QPRRegClassID:
164 case ARM::QQPRRegClassID:
165 case ARM::QQQQPRRegClassID:
166 case ARM::GPRPairRegClassID:
174 const TargetRegisterClass *
175 ARMBaseRegisterInfo::getPointerRegClass(const MachineFunction &MF, unsigned Kind)
177 return &ARM::GPRRegClass;
180 const TargetRegisterClass *
181 ARMBaseRegisterInfo::getCrossCopyRegClass(const TargetRegisterClass *RC) const {
182 if (RC == &ARM::CCRRegClass)
183 return &ARM::rGPRRegClass; // Can't copy CCR registers.
188 ARMBaseRegisterInfo::getRegPressureLimit(const TargetRegisterClass *RC,
189 MachineFunction &MF) const {
190 const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
192 switch (RC->getID()) {
195 case ARM::tGPRRegClassID:
196 return TFI->hasFP(MF) ? 4 : 5;
197 case ARM::GPRRegClassID: {
198 unsigned FP = TFI->hasFP(MF) ? 1 : 0;
199 return 10 - FP - (STI.isR9Reserved() ? 1 : 0);
201 case ARM::SPRRegClassID: // Currently not used as 'rep' register class.
202 case ARM::DPRRegClassID:
207 // Get the other register in a GPRPair.
208 static unsigned getPairedGPR(unsigned Reg, bool Odd, const MCRegisterInfo *RI) {
209 for (MCSuperRegIterator Supers(Reg, RI); Supers.isValid(); ++Supers)
210 if (ARM::GPRPairRegClass.contains(*Supers))
211 return RI->getSubReg(*Supers, Odd ? ARM::gsub_1 : ARM::gsub_0);
215 // Resolve the RegPairEven / RegPairOdd register allocator hints.
217 ARMBaseRegisterInfo::getRegAllocationHints(unsigned VirtReg,
218 ArrayRef<MCPhysReg> Order,
219 SmallVectorImpl<MCPhysReg> &Hints,
220 const MachineFunction &MF,
221 const VirtRegMap *VRM) const {
222 const MachineRegisterInfo &MRI = MF.getRegInfo();
223 std::pair<unsigned, unsigned> Hint = MRI.getRegAllocationHint(VirtReg);
226 switch (Hint.first) {
227 case ARMRI::RegPairEven:
230 case ARMRI::RegPairOdd:
234 TargetRegisterInfo::getRegAllocationHints(VirtReg, Order, Hints, MF, VRM);
238 // This register should preferably be even (Odd == 0) or odd (Odd == 1).
239 // Check if the other part of the pair has already been assigned, and provide
240 // the paired register as the first hint.
241 unsigned PairedPhys = 0;
242 if (VRM && VRM->hasPhys(Hint.second)) {
243 PairedPhys = getPairedGPR(VRM->getPhys(Hint.second), Odd, this);
244 if (PairedPhys && MRI.isReserved(PairedPhys))
248 // First prefer the paired physreg.
250 std::find(Order.begin(), Order.end(), PairedPhys) != Order.end())
251 Hints.push_back(PairedPhys);
253 // Then prefer even or odd registers.
254 for (unsigned I = 0, E = Order.size(); I != E; ++I) {
255 unsigned Reg = Order[I];
256 if (Reg == PairedPhys || (getEncodingValue(Reg) & 1) != Odd)
258 // Don't provide hints that are paired to a reserved register.
259 unsigned Paired = getPairedGPR(Reg, !Odd, this);
260 if (!Paired || MRI.isReserved(Paired))
262 Hints.push_back(Reg);
267 ARMBaseRegisterInfo::UpdateRegAllocHint(unsigned Reg, unsigned NewReg,
268 MachineFunction &MF) const {
269 MachineRegisterInfo *MRI = &MF.getRegInfo();
270 std::pair<unsigned, unsigned> Hint = MRI->getRegAllocationHint(Reg);
271 if ((Hint.first == (unsigned)ARMRI::RegPairOdd ||
272 Hint.first == (unsigned)ARMRI::RegPairEven) &&
273 TargetRegisterInfo::isVirtualRegister(Hint.second)) {
274 // If 'Reg' is one of the even / odd register pair and it's now changed
275 // (e.g. coalesced) into a different register. The other register of the
276 // pair allocation hint must be updated to reflect the relationship
278 unsigned OtherReg = Hint.second;
279 Hint = MRI->getRegAllocationHint(OtherReg);
280 if (Hint.second == Reg)
281 // Make sure the pair has not already divorced.
282 MRI->setRegAllocationHint(OtherReg, Hint.first, NewReg);
287 ARMBaseRegisterInfo::avoidWriteAfterWrite(const TargetRegisterClass *RC) const {
288 // CortexA9 has a Write-after-write hazard for NEON registers.
292 switch (RC->getID()) {
293 case ARM::DPRRegClassID:
294 case ARM::DPR_8RegClassID:
295 case ARM::DPR_VFP2RegClassID:
296 case ARM::QPRRegClassID:
297 case ARM::QPR_8RegClassID:
298 case ARM::QPR_VFP2RegClassID:
299 case ARM::SPRRegClassID:
300 case ARM::SPR_8RegClassID:
301 // Avoid reusing S, D, and Q registers.
302 // Don't increase register pressure for QQ and QQQQ.
309 bool ARMBaseRegisterInfo::hasBasePointer(const MachineFunction &MF) const {
310 const MachineFrameInfo *MFI = MF.getFrameInfo();
311 const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
312 const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
314 // When outgoing call frames are so large that we adjust the stack pointer
315 // around the call, we can no longer use the stack pointer to reach the
316 // emergency spill slot.
317 if (needsStackRealignment(MF) && !TFI->hasReservedCallFrame(MF))
320 // Thumb has trouble with negative offsets from the FP. Thumb2 has a limited
321 // negative range for ldr/str (255), and thumb1 is positive offsets only.
322 // It's going to be better to use the SP or Base Pointer instead. When there
323 // are variable sized objects, we can't reference off of the SP, so we
324 // reserve a Base Pointer.
325 if (AFI->isThumbFunction() && MFI->hasVarSizedObjects()) {
326 // Conservatively estimate whether the negative offset from the frame
327 // pointer will be sufficient to reach. If a function has a smallish
328 // frame, it's less likely to have lots of spills and callee saved
329 // space, so it's all more likely to be within range of the frame pointer.
330 // If it's wrong, the scavenger will still enable access to work, it just
332 if (AFI->isThumb2Function() && MFI->getLocalFrameSize() < 128)
340 bool ARMBaseRegisterInfo::canRealignStack(const MachineFunction &MF) const {
341 const MachineRegisterInfo *MRI = &MF.getRegInfo();
342 const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
343 // We can't realign the stack if:
344 // 1. Dynamic stack realignment is explicitly disabled,
345 // 2. This is a Thumb1 function (it's not useful, so we don't bother), or
346 // 3. There are VLAs in the function and the base pointer is disabled.
347 if (MF.getFunction()->hasFnAttribute("no-realign-stack"))
349 if (AFI->isThumb1OnlyFunction())
351 // Stack realignment requires a frame pointer. If we already started
352 // register allocation with frame pointer elimination, it is too late now.
353 if (!MRI->canReserveReg(FramePtr))
355 // We may also need a base pointer if there are dynamic allocas or stack
356 // pointer adjustments around calls.
357 if (MF.getSubtarget().getFrameLowering()->hasReservedCallFrame(MF))
359 // A base pointer is required and allowed. Check that it isn't too late to
361 return MRI->canReserveReg(BasePtr);
364 bool ARMBaseRegisterInfo::
365 needsStackRealignment(const MachineFunction &MF) const {
366 const MachineFrameInfo *MFI = MF.getFrameInfo();
367 const Function *F = MF.getFunction();
368 unsigned StackAlign =
369 MF.getSubtarget().getFrameLowering()->getStackAlignment();
370 bool requiresRealignment = ((MFI->getMaxAlignment() > StackAlign) ||
371 F->hasFnAttribute(Attribute::StackAlignment));
373 return requiresRealignment && canRealignStack(MF);
376 bool ARMBaseRegisterInfo::
377 cannotEliminateFrame(const MachineFunction &MF) const {
378 const MachineFrameInfo *MFI = MF.getFrameInfo();
379 if (MF.getTarget().Options.DisableFramePointerElim(MF) && MFI->adjustsStack())
381 return MFI->hasVarSizedObjects() || MFI->isFrameAddressTaken()
382 || needsStackRealignment(MF);
386 ARMBaseRegisterInfo::getFrameRegister(const MachineFunction &MF) const {
387 const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
394 /// emitLoadConstPool - Emits a load from constpool to materialize the
395 /// specified immediate.
396 void ARMBaseRegisterInfo::
397 emitLoadConstPool(MachineBasicBlock &MBB,
398 MachineBasicBlock::iterator &MBBI,
400 unsigned DestReg, unsigned SubIdx, int Val,
401 ARMCC::CondCodes Pred,
402 unsigned PredReg, unsigned MIFlags) const {
403 MachineFunction &MF = *MBB.getParent();
404 const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
405 MachineConstantPool *ConstantPool = MF.getConstantPool();
407 ConstantInt::get(Type::getInt32Ty(MF.getFunction()->getContext()), Val);
408 unsigned Idx = ConstantPool->getConstantPoolIndex(C, 4);
410 BuildMI(MBB, MBBI, dl, TII.get(ARM::LDRcp))
411 .addReg(DestReg, getDefRegState(true), SubIdx)
412 .addConstantPoolIndex(Idx)
413 .addImm(0).addImm(Pred).addReg(PredReg)
414 .setMIFlags(MIFlags);
417 bool ARMBaseRegisterInfo::
418 requiresRegisterScavenging(const MachineFunction &MF) const {
422 bool ARMBaseRegisterInfo::
423 trackLivenessAfterRegAlloc(const MachineFunction &MF) const {
427 bool ARMBaseRegisterInfo::
428 requiresFrameIndexScavenging(const MachineFunction &MF) const {
432 bool ARMBaseRegisterInfo::
433 requiresVirtualBaseRegisters(const MachineFunction &MF) const {
437 int64_t ARMBaseRegisterInfo::
438 getFrameIndexInstrOffset(const MachineInstr *MI, int Idx) const {
439 const MCInstrDesc &Desc = MI->getDesc();
440 unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
441 int64_t InstrOffs = 0;
445 case ARMII::AddrModeT2_i8:
446 case ARMII::AddrModeT2_i12:
447 case ARMII::AddrMode_i12:
448 InstrOffs = MI->getOperand(Idx+1).getImm();
451 case ARMII::AddrMode5: {
453 const MachineOperand &OffOp = MI->getOperand(Idx+1);
454 InstrOffs = ARM_AM::getAM5Offset(OffOp.getImm());
455 if (ARM_AM::getAM5Op(OffOp.getImm()) == ARM_AM::sub)
456 InstrOffs = -InstrOffs;
460 case ARMII::AddrMode2: {
462 InstrOffs = ARM_AM::getAM2Offset(MI->getOperand(ImmIdx).getImm());
463 if (ARM_AM::getAM2Op(MI->getOperand(ImmIdx).getImm()) == ARM_AM::sub)
464 InstrOffs = -InstrOffs;
467 case ARMII::AddrMode3: {
469 InstrOffs = ARM_AM::getAM3Offset(MI->getOperand(ImmIdx).getImm());
470 if (ARM_AM::getAM3Op(MI->getOperand(ImmIdx).getImm()) == ARM_AM::sub)
471 InstrOffs = -InstrOffs;
474 case ARMII::AddrModeT1_s: {
476 InstrOffs = MI->getOperand(ImmIdx).getImm();
481 llvm_unreachable("Unsupported addressing mode!");
484 return InstrOffs * Scale;
487 /// needsFrameBaseReg - Returns true if the instruction's frame index
488 /// reference would be better served by a base register other than FP
489 /// or SP. Used by LocalStackFrameAllocation to determine which frame index
490 /// references it should create new base registers for.
491 bool ARMBaseRegisterInfo::
492 needsFrameBaseReg(MachineInstr *MI, int64_t Offset) const {
493 for (unsigned i = 0; !MI->getOperand(i).isFI(); ++i) {
494 assert(i < MI->getNumOperands() &&"Instr doesn't have FrameIndex operand!");
497 // It's the load/store FI references that cause issues, as it can be difficult
498 // to materialize the offset if it won't fit in the literal field. Estimate
499 // based on the size of the local frame and some conservative assumptions
500 // about the rest of the stack frame (note, this is pre-regalloc, so
501 // we don't know everything for certain yet) whether this offset is likely
502 // to be out of range of the immediate. Return true if so.
504 // We only generate virtual base registers for loads and stores, so
505 // return false for everything else.
506 unsigned Opc = MI->getOpcode();
508 case ARM::LDRi12: case ARM::LDRH: case ARM::LDRBi12:
509 case ARM::STRi12: case ARM::STRH: case ARM::STRBi12:
510 case ARM::t2LDRi12: case ARM::t2LDRi8:
511 case ARM::t2STRi12: case ARM::t2STRi8:
512 case ARM::VLDRS: case ARM::VLDRD:
513 case ARM::VSTRS: case ARM::VSTRD:
514 case ARM::tSTRspi: case ARM::tLDRspi:
520 // Without a virtual base register, if the function has variable sized
521 // objects, all fixed-size local references will be via the frame pointer,
522 // Approximate the offset and see if it's legal for the instruction.
523 // Note that the incoming offset is based on the SP value at function entry,
524 // so it'll be negative.
525 MachineFunction &MF = *MI->getParent()->getParent();
526 const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
527 MachineFrameInfo *MFI = MF.getFrameInfo();
528 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
530 // Estimate an offset from the frame pointer.
531 // Conservatively assume all callee-saved registers get pushed. R4-R6
532 // will be earlier than the FP, so we ignore those.
534 int64_t FPOffset = Offset - 8;
535 // ARM and Thumb2 functions also need to consider R8-R11 and D8-D15
536 if (!AFI->isThumbFunction() || !AFI->isThumb1OnlyFunction())
538 // Estimate an offset from the stack pointer.
539 // The incoming offset is relating to the SP at the start of the function,
540 // but when we access the local it'll be relative to the SP after local
541 // allocation, so adjust our SP-relative offset by that allocation size.
543 Offset += MFI->getLocalFrameSize();
544 // Assume that we'll have at least some spill slots allocated.
545 // FIXME: This is a total SWAG number. We should run some statistics
546 // and pick a real one.
547 Offset += 128; // 128 bytes of spill slots
549 // If there is a frame pointer, try using it.
550 // The FP is only available if there is no dynamic realignment. We
551 // don't know for sure yet whether we'll need that, so we guess based
552 // on whether there are any local variables that would trigger it.
553 unsigned StackAlign = TFI->getStackAlignment();
554 if (TFI->hasFP(MF) &&
555 !((MFI->getLocalFrameMaxAlign() > StackAlign) && canRealignStack(MF))) {
556 if (isFrameOffsetLegal(MI, FPOffset))
559 // If we can reference via the stack pointer, try that.
560 // FIXME: This (and the code that resolves the references) can be improved
561 // to only disallow SP relative references in the live range of
562 // the VLA(s). In practice, it's unclear how much difference that
563 // would make, but it may be worth doing.
564 if (!MFI->hasVarSizedObjects() && isFrameOffsetLegal(MI, Offset))
567 // The offset likely isn't legal, we want to allocate a virtual base register.
571 /// materializeFrameBaseRegister - Insert defining instruction(s) for BaseReg to
572 /// be a pointer to FrameIdx at the beginning of the basic block.
573 void ARMBaseRegisterInfo::
574 materializeFrameBaseRegister(MachineBasicBlock *MBB,
575 unsigned BaseReg, int FrameIdx,
576 int64_t Offset) const {
577 ARMFunctionInfo *AFI = MBB->getParent()->getInfo<ARMFunctionInfo>();
578 unsigned ADDriOpc = !AFI->isThumbFunction() ? ARM::ADDri :
579 (AFI->isThumb1OnlyFunction() ? ARM::tADDframe : ARM::t2ADDri);
581 MachineBasicBlock::iterator Ins = MBB->begin();
582 DebugLoc DL; // Defaults to "unknown"
583 if (Ins != MBB->end())
584 DL = Ins->getDebugLoc();
586 const MachineFunction &MF = *MBB->getParent();
587 MachineRegisterInfo &MRI = MBB->getParent()->getRegInfo();
588 const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
589 const MCInstrDesc &MCID = TII.get(ADDriOpc);
590 MRI.constrainRegClass(BaseReg, TII.getRegClass(MCID, 0, this, MF));
592 MachineInstrBuilder MIB = BuildMI(*MBB, Ins, DL, MCID, BaseReg)
593 .addFrameIndex(FrameIdx).addImm(Offset);
595 if (!AFI->isThumb1OnlyFunction())
596 AddDefaultCC(AddDefaultPred(MIB));
599 void ARMBaseRegisterInfo::resolveFrameIndex(MachineInstr &MI, unsigned BaseReg,
600 int64_t Offset) const {
601 MachineBasicBlock &MBB = *MI.getParent();
602 MachineFunction &MF = *MBB.getParent();
603 const ARMBaseInstrInfo &TII =
604 *static_cast<const ARMBaseInstrInfo *>(MF.getSubtarget().getInstrInfo());
605 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
606 int Off = Offset; // ARM doesn't need the general 64-bit offsets
609 assert(!AFI->isThumb1OnlyFunction() &&
610 "This resolveFrameIndex does not support Thumb1!");
612 while (!MI.getOperand(i).isFI()) {
614 assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
617 if (!AFI->isThumbFunction())
618 Done = rewriteARMFrameIndex(MI, i, BaseReg, Off, TII);
620 assert(AFI->isThumb2Function());
621 Done = rewriteT2FrameIndex(MI, i, BaseReg, Off, TII);
623 assert (Done && "Unable to resolve frame index!");
627 bool ARMBaseRegisterInfo::isFrameOffsetLegal(const MachineInstr *MI,
628 int64_t Offset) const {
629 const MCInstrDesc &Desc = MI->getDesc();
630 unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
633 while (!MI->getOperand(i).isFI()) {
635 assert(i < MI->getNumOperands() &&"Instr doesn't have FrameIndex operand!");
638 // AddrMode4 and AddrMode6 cannot handle any offset.
639 if (AddrMode == ARMII::AddrMode4 || AddrMode == ARMII::AddrMode6)
642 unsigned NumBits = 0;
644 bool isSigned = true;
646 case ARMII::AddrModeT2_i8:
647 case ARMII::AddrModeT2_i12:
648 // i8 supports only negative, and i12 supports only positive, so
649 // based on Offset sign, consider the appropriate instruction
658 case ARMII::AddrMode5:
663 case ARMII::AddrMode_i12:
664 case ARMII::AddrMode2:
667 case ARMII::AddrMode3:
670 case ARMII::AddrModeT1_s:
676 llvm_unreachable("Unsupported addressing mode!");
679 Offset += getFrameIndexInstrOffset(MI, i);
680 // Make sure the offset is encodable for instructions that scale the
682 if ((Offset & (Scale-1)) != 0)
685 if (isSigned && Offset < 0)
688 unsigned Mask = (1 << NumBits) - 1;
689 if ((unsigned)Offset <= Mask * Scale)
696 ARMBaseRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
697 int SPAdj, unsigned FIOperandNum,
698 RegScavenger *RS) const {
699 MachineInstr &MI = *II;
700 MachineBasicBlock &MBB = *MI.getParent();
701 MachineFunction &MF = *MBB.getParent();
702 const ARMBaseInstrInfo &TII =
703 *static_cast<const ARMBaseInstrInfo *>(MF.getSubtarget().getInstrInfo());
704 const ARMFrameLowering *TFI = static_cast<const ARMFrameLowering *>(
705 MF.getSubtarget().getFrameLowering());
706 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
707 assert(!AFI->isThumb1OnlyFunction() &&
708 "This eliminateFrameIndex does not support Thumb1!");
709 int FrameIndex = MI.getOperand(FIOperandNum).getIndex();
712 int Offset = TFI->ResolveFrameIndexReference(MF, FrameIndex, FrameReg, SPAdj);
714 // PEI::scavengeFrameVirtualRegs() cannot accurately track SPAdj because the
715 // call frame setup/destroy instructions have already been eliminated. That
716 // means the stack pointer cannot be used to access the emergency spill slot
717 // when !hasReservedCallFrame().
719 if (RS && FrameReg == ARM::SP && RS->isScavengingFrameIndex(FrameIndex)){
720 assert(TFI->hasReservedCallFrame(MF) &&
721 "Cannot use SP to access the emergency spill slot in "
722 "functions without a reserved call frame");
723 assert(!MF.getFrameInfo()->hasVarSizedObjects() &&
724 "Cannot use SP to access the emergency spill slot in "
725 "functions with variable sized frame objects");
729 assert(!MI.isDebugValue() && "DBG_VALUEs should be handled in target-independent code");
731 // Modify MI as necessary to handle as much of 'Offset' as possible
733 if (!AFI->isThumbFunction())
734 Done = rewriteARMFrameIndex(MI, FIOperandNum, FrameReg, Offset, TII);
736 assert(AFI->isThumb2Function());
737 Done = rewriteT2FrameIndex(MI, FIOperandNum, FrameReg, Offset, TII);
742 // If we get here, the immediate doesn't fit into the instruction. We folded
743 // as much as possible above, handle the rest, providing a register that is
746 (MI.getDesc().TSFlags & ARMII::AddrModeMask) == ARMII::AddrMode4 ||
747 (MI.getDesc().TSFlags & ARMII::AddrModeMask) == ARMII::AddrMode6) &&
748 "This code isn't needed if offset already handled!");
750 unsigned ScratchReg = 0;
751 int PIdx = MI.findFirstPredOperandIdx();
752 ARMCC::CondCodes Pred = (PIdx == -1)
753 ? ARMCC::AL : (ARMCC::CondCodes)MI.getOperand(PIdx).getImm();
754 unsigned PredReg = (PIdx == -1) ? 0 : MI.getOperand(PIdx+1).getReg();
756 // Must be addrmode4/6.
757 MI.getOperand(FIOperandNum).ChangeToRegister(FrameReg, false, false, false);
759 ScratchReg = MF.getRegInfo().createVirtualRegister(&ARM::GPRRegClass);
760 if (!AFI->isThumbFunction())
761 emitARMRegPlusImmediate(MBB, II, MI.getDebugLoc(), ScratchReg, FrameReg,
762 Offset, Pred, PredReg, TII);
764 assert(AFI->isThumb2Function());
765 emitT2RegPlusImmediate(MBB, II, MI.getDebugLoc(), ScratchReg, FrameReg,
766 Offset, Pred, PredReg, TII);
768 // Update the original instruction to use the scratch register.
769 MI.getOperand(FIOperandNum).ChangeToRegister(ScratchReg, false, false,true);
773 bool ARMBaseRegisterInfo::shouldCoalesce(MachineInstr *MI,
774 const TargetRegisterClass *SrcRC,
776 const TargetRegisterClass *DstRC,
778 const TargetRegisterClass *NewRC) const {
779 auto MBB = MI->getParent();
780 auto MF = MBB->getParent();
781 const MachineRegisterInfo &MRI = MF->getRegInfo();
782 // If not copying into a sub-register this should be ok because we shouldn't
783 // need to split the reg.
786 // Small registers don't frequently cause a problem, so we can coalesce them.
787 if (NewRC->getSize() < 32 && DstRC->getSize() < 32 && SrcRC->getSize() < 32)
791 MRI.getTargetRegisterInfo()->getRegClassWeight(NewRC);
793 MRI.getTargetRegisterInfo()->getRegClassWeight(SrcRC);
795 MRI.getTargetRegisterInfo()->getRegClassWeight(DstRC);
796 // If the source register class is more expensive than the destination, the
797 // coalescing is probably profitable.
798 if (SrcRCWeight.RegWeight > NewRCWeight.RegWeight)
800 if (DstRCWeight.RegWeight > NewRCWeight.RegWeight)
803 // If the register allocator isn't constrained, we can always allow coalescing
804 // unfortunately we don't know yet if we will be constrained.
805 // The goal of this heuristic is to restrict how many expensive registers
806 // we allow to coalesce in a given basic block.
807 auto AFI = MF->getInfo<ARMFunctionInfo>();
808 auto It = AFI->getCoalescedWeight(MBB);
810 DEBUG(dbgs() << "\tARM::shouldCoalesce - Coalesced Weight: "
811 << It->second << "\n");
812 DEBUG(dbgs() << "\tARM::shouldCoalesce - Reg Weight: "
813 << NewRCWeight.RegWeight << "\n");
815 // This number is the largest round number that which meets the criteria:
816 // (1) addresses PR18825
817 // (2) generates better code in some test cases (like vldm-shed-a9.ll)
818 // (3) Doesn't regress any test cases (in-tree, test-suite, and SPEC)
819 // In practice the SizeMultiplier will only factor in for straight line code
820 // that uses a lot of NEON vectors, which isn't terribly common.
821 unsigned SizeMultiplier = MBB->size()/100;
822 SizeMultiplier = SizeMultiplier ? SizeMultiplier : 1;
823 if (It->second < NewRCWeight.WeightLimit * SizeMultiplier) {
824 It->second += NewRCWeight.RegWeight;