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,
155 const MachineFunction &) const {
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);
286 bool ARMBaseRegisterInfo::hasBasePointer(const MachineFunction &MF) const {
287 const MachineFrameInfo *MFI = MF.getFrameInfo();
288 const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
289 const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
291 // When outgoing call frames are so large that we adjust the stack pointer
292 // around the call, we can no longer use the stack pointer to reach the
293 // emergency spill slot.
294 if (needsStackRealignment(MF) && !TFI->hasReservedCallFrame(MF))
297 // Thumb has trouble with negative offsets from the FP. Thumb2 has a limited
298 // negative range for ldr/str (255), and thumb1 is positive offsets only.
299 // It's going to be better to use the SP or Base Pointer instead. When there
300 // are variable sized objects, we can't reference off of the SP, so we
301 // reserve a Base Pointer.
302 if (AFI->isThumbFunction() && MFI->hasVarSizedObjects()) {
303 // Conservatively estimate whether the negative offset from the frame
304 // pointer will be sufficient to reach. If a function has a smallish
305 // frame, it's less likely to have lots of spills and callee saved
306 // space, so it's all more likely to be within range of the frame pointer.
307 // If it's wrong, the scavenger will still enable access to work, it just
309 if (AFI->isThumb2Function() && MFI->getLocalFrameSize() < 128)
317 bool ARMBaseRegisterInfo::canRealignStack(const MachineFunction &MF) const {
318 const MachineRegisterInfo *MRI = &MF.getRegInfo();
319 const ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
320 // We can't realign the stack if:
321 // 1. Dynamic stack realignment is explicitly disabled,
322 // 2. This is a Thumb1 function (it's not useful, so we don't bother), or
323 // 3. There are VLAs in the function and the base pointer is disabled.
324 if (MF.getFunction()->hasFnAttribute("no-realign-stack"))
326 if (AFI->isThumb1OnlyFunction())
328 // Stack realignment requires a frame pointer. If we already started
329 // register allocation with frame pointer elimination, it is too late now.
330 if (!MRI->canReserveReg(FramePtr))
332 // We may also need a base pointer if there are dynamic allocas or stack
333 // pointer adjustments around calls.
334 if (MF.getSubtarget().getFrameLowering()->hasReservedCallFrame(MF))
336 // A base pointer is required and allowed. Check that it isn't too late to
338 return MRI->canReserveReg(BasePtr);
341 bool ARMBaseRegisterInfo::
342 needsStackRealignment(const MachineFunction &MF) const {
343 const MachineFrameInfo *MFI = MF.getFrameInfo();
344 const Function *F = MF.getFunction();
345 unsigned StackAlign =
346 MF.getSubtarget().getFrameLowering()->getStackAlignment();
347 bool requiresRealignment = ((MFI->getMaxAlignment() > StackAlign) ||
348 F->hasFnAttribute(Attribute::StackAlignment));
350 return requiresRealignment && canRealignStack(MF);
353 bool ARMBaseRegisterInfo::
354 cannotEliminateFrame(const MachineFunction &MF) const {
355 const MachineFrameInfo *MFI = MF.getFrameInfo();
356 if (MF.getTarget().Options.DisableFramePointerElim(MF) && MFI->adjustsStack())
358 return MFI->hasVarSizedObjects() || MFI->isFrameAddressTaken()
359 || needsStackRealignment(MF);
363 ARMBaseRegisterInfo::getFrameRegister(const MachineFunction &MF) const {
364 const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
371 /// emitLoadConstPool - Emits a load from constpool to materialize the
372 /// specified immediate.
373 void ARMBaseRegisterInfo::
374 emitLoadConstPool(MachineBasicBlock &MBB,
375 MachineBasicBlock::iterator &MBBI,
377 unsigned DestReg, unsigned SubIdx, int Val,
378 ARMCC::CondCodes Pred,
379 unsigned PredReg, unsigned MIFlags) const {
380 MachineFunction &MF = *MBB.getParent();
381 const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
382 MachineConstantPool *ConstantPool = MF.getConstantPool();
384 ConstantInt::get(Type::getInt32Ty(MF.getFunction()->getContext()), Val);
385 unsigned Idx = ConstantPool->getConstantPoolIndex(C, 4);
387 BuildMI(MBB, MBBI, dl, TII.get(ARM::LDRcp))
388 .addReg(DestReg, getDefRegState(true), SubIdx)
389 .addConstantPoolIndex(Idx)
390 .addImm(0).addImm(Pred).addReg(PredReg)
391 .setMIFlags(MIFlags);
394 bool ARMBaseRegisterInfo::
395 requiresRegisterScavenging(const MachineFunction &MF) const {
399 bool ARMBaseRegisterInfo::
400 trackLivenessAfterRegAlloc(const MachineFunction &MF) const {
404 bool ARMBaseRegisterInfo::
405 requiresFrameIndexScavenging(const MachineFunction &MF) const {
409 bool ARMBaseRegisterInfo::
410 requiresVirtualBaseRegisters(const MachineFunction &MF) const {
414 int64_t ARMBaseRegisterInfo::
415 getFrameIndexInstrOffset(const MachineInstr *MI, int Idx) const {
416 const MCInstrDesc &Desc = MI->getDesc();
417 unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
418 int64_t InstrOffs = 0;
422 case ARMII::AddrModeT2_i8:
423 case ARMII::AddrModeT2_i12:
424 case ARMII::AddrMode_i12:
425 InstrOffs = MI->getOperand(Idx+1).getImm();
428 case ARMII::AddrMode5: {
430 const MachineOperand &OffOp = MI->getOperand(Idx+1);
431 InstrOffs = ARM_AM::getAM5Offset(OffOp.getImm());
432 if (ARM_AM::getAM5Op(OffOp.getImm()) == ARM_AM::sub)
433 InstrOffs = -InstrOffs;
437 case ARMII::AddrMode2: {
439 InstrOffs = ARM_AM::getAM2Offset(MI->getOperand(ImmIdx).getImm());
440 if (ARM_AM::getAM2Op(MI->getOperand(ImmIdx).getImm()) == ARM_AM::sub)
441 InstrOffs = -InstrOffs;
444 case ARMII::AddrMode3: {
446 InstrOffs = ARM_AM::getAM3Offset(MI->getOperand(ImmIdx).getImm());
447 if (ARM_AM::getAM3Op(MI->getOperand(ImmIdx).getImm()) == ARM_AM::sub)
448 InstrOffs = -InstrOffs;
451 case ARMII::AddrModeT1_s: {
453 InstrOffs = MI->getOperand(ImmIdx).getImm();
458 llvm_unreachable("Unsupported addressing mode!");
461 return InstrOffs * Scale;
464 /// needsFrameBaseReg - Returns true if the instruction's frame index
465 /// reference would be better served by a base register other than FP
466 /// or SP. Used by LocalStackFrameAllocation to determine which frame index
467 /// references it should create new base registers for.
468 bool ARMBaseRegisterInfo::
469 needsFrameBaseReg(MachineInstr *MI, int64_t Offset) const {
470 for (unsigned i = 0; !MI->getOperand(i).isFI(); ++i) {
471 assert(i < MI->getNumOperands() &&"Instr doesn't have FrameIndex operand!");
474 // It's the load/store FI references that cause issues, as it can be difficult
475 // to materialize the offset if it won't fit in the literal field. Estimate
476 // based on the size of the local frame and some conservative assumptions
477 // about the rest of the stack frame (note, this is pre-regalloc, so
478 // we don't know everything for certain yet) whether this offset is likely
479 // to be out of range of the immediate. Return true if so.
481 // We only generate virtual base registers for loads and stores, so
482 // return false for everything else.
483 unsigned Opc = MI->getOpcode();
485 case ARM::LDRi12: case ARM::LDRH: case ARM::LDRBi12:
486 case ARM::STRi12: case ARM::STRH: case ARM::STRBi12:
487 case ARM::t2LDRi12: case ARM::t2LDRi8:
488 case ARM::t2STRi12: case ARM::t2STRi8:
489 case ARM::VLDRS: case ARM::VLDRD:
490 case ARM::VSTRS: case ARM::VSTRD:
491 case ARM::tSTRspi: case ARM::tLDRspi:
497 // Without a virtual base register, if the function has variable sized
498 // objects, all fixed-size local references will be via the frame pointer,
499 // Approximate the offset and see if it's legal for the instruction.
500 // Note that the incoming offset is based on the SP value at function entry,
501 // so it'll be negative.
502 MachineFunction &MF = *MI->getParent()->getParent();
503 const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
504 MachineFrameInfo *MFI = MF.getFrameInfo();
505 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
507 // Estimate an offset from the frame pointer.
508 // Conservatively assume all callee-saved registers get pushed. R4-R6
509 // will be earlier than the FP, so we ignore those.
511 int64_t FPOffset = Offset - 8;
512 // ARM and Thumb2 functions also need to consider R8-R11 and D8-D15
513 if (!AFI->isThumbFunction() || !AFI->isThumb1OnlyFunction())
515 // Estimate an offset from the stack pointer.
516 // The incoming offset is relating to the SP at the start of the function,
517 // but when we access the local it'll be relative to the SP after local
518 // allocation, so adjust our SP-relative offset by that allocation size.
520 Offset += MFI->getLocalFrameSize();
521 // Assume that we'll have at least some spill slots allocated.
522 // FIXME: This is a total SWAG number. We should run some statistics
523 // and pick a real one.
524 Offset += 128; // 128 bytes of spill slots
526 // If there's a frame pointer and the addressing mode allows it, try using it.
527 // The FP is only available if there is no dynamic realignment. We
528 // don't know for sure yet whether we'll need that, so we guess based
529 // on whether there are any local variables that would trigger it.
530 unsigned StackAlign = TFI->getStackAlignment();
531 if (TFI->hasFP(MF) &&
532 (MI->getDesc().TSFlags & ARMII::AddrModeMask) != ARMII::AddrModeT1_s &&
533 !((MFI->getLocalFrameMaxAlign() > StackAlign) && canRealignStack(MF))) {
534 if (isFrameOffsetLegal(MI, FPOffset))
537 // If we can reference via the stack pointer, try that.
538 // FIXME: This (and the code that resolves the references) can be improved
539 // to only disallow SP relative references in the live range of
540 // the VLA(s). In practice, it's unclear how much difference that
541 // would make, but it may be worth doing.
542 if (!MFI->hasVarSizedObjects() && isFrameOffsetLegal(MI, Offset))
545 // The offset likely isn't legal, we want to allocate a virtual base register.
549 /// materializeFrameBaseRegister - Insert defining instruction(s) for BaseReg to
550 /// be a pointer to FrameIdx at the beginning of the basic block.
551 void ARMBaseRegisterInfo::
552 materializeFrameBaseRegister(MachineBasicBlock *MBB,
553 unsigned BaseReg, int FrameIdx,
554 int64_t Offset) const {
555 ARMFunctionInfo *AFI = MBB->getParent()->getInfo<ARMFunctionInfo>();
556 unsigned ADDriOpc = !AFI->isThumbFunction() ? ARM::ADDri :
557 (AFI->isThumb1OnlyFunction() ? ARM::tADDframe : ARM::t2ADDri);
559 MachineBasicBlock::iterator Ins = MBB->begin();
560 DebugLoc DL; // Defaults to "unknown"
561 if (Ins != MBB->end())
562 DL = Ins->getDebugLoc();
564 const MachineFunction &MF = *MBB->getParent();
565 MachineRegisterInfo &MRI = MBB->getParent()->getRegInfo();
566 const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
567 const MCInstrDesc &MCID = TII.get(ADDriOpc);
568 MRI.constrainRegClass(BaseReg, TII.getRegClass(MCID, 0, this, MF));
570 MachineInstrBuilder MIB = BuildMI(*MBB, Ins, DL, MCID, BaseReg)
571 .addFrameIndex(FrameIdx).addImm(Offset);
573 if (!AFI->isThumb1OnlyFunction())
574 AddDefaultCC(AddDefaultPred(MIB));
577 void ARMBaseRegisterInfo::resolveFrameIndex(MachineInstr &MI, unsigned BaseReg,
578 int64_t Offset) const {
579 MachineBasicBlock &MBB = *MI.getParent();
580 MachineFunction &MF = *MBB.getParent();
581 const ARMBaseInstrInfo &TII =
582 *static_cast<const ARMBaseInstrInfo *>(MF.getSubtarget().getInstrInfo());
583 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
584 int Off = Offset; // ARM doesn't need the general 64-bit offsets
587 assert(!AFI->isThumb1OnlyFunction() &&
588 "This resolveFrameIndex does not support Thumb1!");
590 while (!MI.getOperand(i).isFI()) {
592 assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
595 if (!AFI->isThumbFunction())
596 Done = rewriteARMFrameIndex(MI, i, BaseReg, Off, TII);
598 assert(AFI->isThumb2Function());
599 Done = rewriteT2FrameIndex(MI, i, BaseReg, Off, TII);
601 assert (Done && "Unable to resolve frame index!");
605 bool ARMBaseRegisterInfo::isFrameOffsetLegal(const MachineInstr *MI,
606 int64_t Offset) const {
607 const MCInstrDesc &Desc = MI->getDesc();
608 unsigned AddrMode = (Desc.TSFlags & ARMII::AddrModeMask);
611 while (!MI->getOperand(i).isFI()) {
613 assert(i < MI->getNumOperands() &&"Instr doesn't have FrameIndex operand!");
616 // AddrMode4 and AddrMode6 cannot handle any offset.
617 if (AddrMode == ARMII::AddrMode4 || AddrMode == ARMII::AddrMode6)
620 unsigned NumBits = 0;
622 bool isSigned = true;
624 case ARMII::AddrModeT2_i8:
625 case ARMII::AddrModeT2_i12:
626 // i8 supports only negative, and i12 supports only positive, so
627 // based on Offset sign, consider the appropriate instruction
636 case ARMII::AddrMode5:
641 case ARMII::AddrMode_i12:
642 case ARMII::AddrMode2:
645 case ARMII::AddrMode3:
648 case ARMII::AddrModeT1_s:
654 llvm_unreachable("Unsupported addressing mode!");
657 Offset += getFrameIndexInstrOffset(MI, i);
658 // Make sure the offset is encodable for instructions that scale the
660 if ((Offset & (Scale-1)) != 0)
663 if (isSigned && Offset < 0)
666 unsigned Mask = (1 << NumBits) - 1;
667 if ((unsigned)Offset <= Mask * Scale)
674 ARMBaseRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
675 int SPAdj, unsigned FIOperandNum,
676 RegScavenger *RS) const {
677 MachineInstr &MI = *II;
678 MachineBasicBlock &MBB = *MI.getParent();
679 MachineFunction &MF = *MBB.getParent();
680 const ARMBaseInstrInfo &TII =
681 *static_cast<const ARMBaseInstrInfo *>(MF.getSubtarget().getInstrInfo());
682 const ARMFrameLowering *TFI = static_cast<const ARMFrameLowering *>(
683 MF.getSubtarget().getFrameLowering());
684 ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
685 assert(!AFI->isThumb1OnlyFunction() &&
686 "This eliminateFrameIndex does not support Thumb1!");
687 int FrameIndex = MI.getOperand(FIOperandNum).getIndex();
690 int Offset = TFI->ResolveFrameIndexReference(MF, FrameIndex, FrameReg, SPAdj);
692 // PEI::scavengeFrameVirtualRegs() cannot accurately track SPAdj because the
693 // call frame setup/destroy instructions have already been eliminated. That
694 // means the stack pointer cannot be used to access the emergency spill slot
695 // when !hasReservedCallFrame().
697 if (RS && FrameReg == ARM::SP && RS->isScavengingFrameIndex(FrameIndex)){
698 assert(TFI->hasReservedCallFrame(MF) &&
699 "Cannot use SP to access the emergency spill slot in "
700 "functions without a reserved call frame");
701 assert(!MF.getFrameInfo()->hasVarSizedObjects() &&
702 "Cannot use SP to access the emergency spill slot in "
703 "functions with variable sized frame objects");
707 assert(!MI.isDebugValue() && "DBG_VALUEs should be handled in target-independent code");
709 // Modify MI as necessary to handle as much of 'Offset' as possible
711 if (!AFI->isThumbFunction())
712 Done = rewriteARMFrameIndex(MI, FIOperandNum, FrameReg, Offset, TII);
714 assert(AFI->isThumb2Function());
715 Done = rewriteT2FrameIndex(MI, FIOperandNum, FrameReg, Offset, TII);
720 // If we get here, the immediate doesn't fit into the instruction. We folded
721 // as much as possible above, handle the rest, providing a register that is
724 (MI.getDesc().TSFlags & ARMII::AddrModeMask) == ARMII::AddrMode4 ||
725 (MI.getDesc().TSFlags & ARMII::AddrModeMask) == ARMII::AddrMode6) &&
726 "This code isn't needed if offset already handled!");
728 unsigned ScratchReg = 0;
729 int PIdx = MI.findFirstPredOperandIdx();
730 ARMCC::CondCodes Pred = (PIdx == -1)
731 ? ARMCC::AL : (ARMCC::CondCodes)MI.getOperand(PIdx).getImm();
732 unsigned PredReg = (PIdx == -1) ? 0 : MI.getOperand(PIdx+1).getReg();
734 // Must be addrmode4/6.
735 MI.getOperand(FIOperandNum).ChangeToRegister(FrameReg, false, false, false);
737 ScratchReg = MF.getRegInfo().createVirtualRegister(&ARM::GPRRegClass);
738 if (!AFI->isThumbFunction())
739 emitARMRegPlusImmediate(MBB, II, MI.getDebugLoc(), ScratchReg, FrameReg,
740 Offset, Pred, PredReg, TII);
742 assert(AFI->isThumb2Function());
743 emitT2RegPlusImmediate(MBB, II, MI.getDebugLoc(), ScratchReg, FrameReg,
744 Offset, Pred, PredReg, TII);
746 // Update the original instruction to use the scratch register.
747 MI.getOperand(FIOperandNum).ChangeToRegister(ScratchReg, false, false,true);
751 bool ARMBaseRegisterInfo::shouldCoalesce(MachineInstr *MI,
752 const TargetRegisterClass *SrcRC,
754 const TargetRegisterClass *DstRC,
756 const TargetRegisterClass *NewRC) const {
757 auto MBB = MI->getParent();
758 auto MF = MBB->getParent();
759 const MachineRegisterInfo &MRI = MF->getRegInfo();
760 // If not copying into a sub-register this should be ok because we shouldn't
761 // need to split the reg.
764 // Small registers don't frequently cause a problem, so we can coalesce them.
765 if (NewRC->getSize() < 32 && DstRC->getSize() < 32 && SrcRC->getSize() < 32)
769 MRI.getTargetRegisterInfo()->getRegClassWeight(NewRC);
771 MRI.getTargetRegisterInfo()->getRegClassWeight(SrcRC);
773 MRI.getTargetRegisterInfo()->getRegClassWeight(DstRC);
774 // If the source register class is more expensive than the destination, the
775 // coalescing is probably profitable.
776 if (SrcRCWeight.RegWeight > NewRCWeight.RegWeight)
778 if (DstRCWeight.RegWeight > NewRCWeight.RegWeight)
781 // If the register allocator isn't constrained, we can always allow coalescing
782 // unfortunately we don't know yet if we will be constrained.
783 // The goal of this heuristic is to restrict how many expensive registers
784 // we allow to coalesce in a given basic block.
785 auto AFI = MF->getInfo<ARMFunctionInfo>();
786 auto It = AFI->getCoalescedWeight(MBB);
788 DEBUG(dbgs() << "\tARM::shouldCoalesce - Coalesced Weight: "
789 << It->second << "\n");
790 DEBUG(dbgs() << "\tARM::shouldCoalesce - Reg Weight: "
791 << NewRCWeight.RegWeight << "\n");
793 // This number is the largest round number that which meets the criteria:
794 // (1) addresses PR18825
795 // (2) generates better code in some test cases (like vldm-shed-a9.ll)
796 // (3) Doesn't regress any test cases (in-tree, test-suite, and SPEC)
797 // In practice the SizeMultiplier will only factor in for straight line code
798 // that uses a lot of NEON vectors, which isn't terribly common.
799 unsigned SizeMultiplier = MBB->size()/100;
800 SizeMultiplier = SizeMultiplier ? SizeMultiplier : 1;
801 if (It->second < NewRCWeight.WeightLimit * SizeMultiplier) {
802 It->second += NewRCWeight.RegWeight;