1 //===-- HexagonFrameLowering.cpp - Define frame lowering ------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
9 //===----------------------------------------------------------------------===//
11 #define DEBUG_TYPE "hexagon-pei"
13 #include "HexagonFrameLowering.h"
15 #include "HexagonInstrInfo.h"
16 #include "HexagonMachineFunctionInfo.h"
17 #include "HexagonRegisterInfo.h"
18 #include "HexagonSubtarget.h"
19 #include "HexagonTargetMachine.h"
20 #include "llvm/ADT/BitVector.h"
21 #include "llvm/ADT/PostOrderIterator.h"
22 #include "llvm/ADT/STLExtras.h"
23 #include "llvm/CodeGen/MachineDominators.h"
24 #include "llvm/CodeGen/MachineInstrBuilder.h"
25 #include "llvm/CodeGen/MachineFunction.h"
26 #include "llvm/CodeGen/MachineFunctionPass.h"
27 #include "llvm/CodeGen/MachineInstrBuilder.h"
28 #include "llvm/CodeGen/MachineModuleInfo.h"
29 #include "llvm/CodeGen/MachinePostDominators.h"
30 #include "llvm/CodeGen/MachineRegisterInfo.h"
31 #include "llvm/CodeGen/RegisterScavenging.h"
32 #include "llvm/IR/Function.h"
33 #include "llvm/IR/Type.h"
34 #include "llvm/Support/CommandLine.h"
35 #include "llvm/Support/Debug.h"
36 #include "llvm/Support/raw_ostream.h"
37 #include "llvm/Target/TargetInstrInfo.h"
38 #include "llvm/Target/TargetMachine.h"
39 #include "llvm/Target/TargetOptions.h"
41 // Hexagon stack frame layout as defined by the ABI:
47 // SP during function's FP during function's |
48 // +-- runtime (top of stack) runtime (bottom) --+ |
50 // --++---------------------+------------------+-----------------++-+-------
51 // | parameter area for | variable-size | fixed-size |LR| arg
52 // | called functions | local objects | local objects |FP|
53 // --+----------------------+------------------+-----------------+--+-------
54 // <- size known -> <- size unknown -> <- size known ->
56 // Low address High address
61 // - In any circumstances, the outgoing function arguments are always accessi-
62 // ble using the SP, and the incoming arguments are accessible using the FP.
63 // - If the local objects are not aligned, they can always be accessed using
65 // - If there are no variable-sized objects, the local objects can always be
66 // accessed using the SP, regardless whether they are aligned or not. (The
67 // alignment padding will be at the bottom of the stack (highest address),
68 // and so the offset with respect to the SP will be known at the compile-
71 // The only complication occurs if there are both, local aligned objects, and
72 // dynamically allocated (variable-sized) objects. The alignment pad will be
73 // placed between the FP and the local objects, thus preventing the use of the
74 // FP to access the local objects. At the same time, the variable-sized objects
75 // will be between the SP and the local objects, thus introducing an unknown
76 // distance from the SP to the locals.
78 // To avoid this problem, a new register is created that holds the aligned
79 // address of the bottom of the stack, referred in the sources as AP (aligned
80 // pointer). The AP will be equal to "FP-p", where "p" is the smallest pad
81 // that aligns AP to the required boundary (a maximum of the alignments of
82 // all stack objects, fixed- and variable-sized). All local objects[1] will
83 // then use AP as the base pointer.
84 // [1] The exception is with "fixed" stack objects. "Fixed" stack objects get
85 // their name from being allocated at fixed locations on the stack, relative
86 // to the FP. In the presence of dynamic allocation and local alignment, such
87 // objects can only be accessed through the FP.
89 // Illustration of the AP:
92 // ---------------+---------------------+-----+-----------------------++-+--
93 // Rest of the | Local stack objects | Pad | Fixed stack objects |LR|
94 // stack frame | (aligned) | | (CSR, spills, etc.) |FP|
95 // ---------------+---------------------+-----+-----------------+-----+--+--
96 // |<-- Multiple of the -->|
97 // stack alignment +-- AP
99 // The AP is set up at the beginning of the function. Since it is not a dedi-
100 // cated (reserved) register, it needs to be kept live throughout the function
101 // to be available as the base register for local object accesses.
102 // Normally, an address of a stack objects is obtained by a pseudo-instruction
103 // TFR_FI. To access local objects with the AP register present, a different
104 // pseudo-instruction needs to be used: TFR_FIA. The TFR_FIA takes one extra
105 // argument compared to TFR_FI: the first input register is the AP register.
106 // This keeps the register live between its definition and its uses.
108 // The AP register is originally set up using pseudo-instruction ALIGNA:
111 // A - required stack alignment
112 // The alignment value must be the maximum of all alignments required by
115 // The dynamic allocation uses a pseudo-instruction ALLOCA:
118 // Rd - address of the allocated space
119 // Rs - minimum size (the actual allocated can be larger to accommodate
121 // A - required alignment
124 using namespace llvm;
126 static cl::opt<bool> DisableDeallocRet("disable-hexagon-dealloc-ret",
127 cl::Hidden, cl::desc("Disable Dealloc Return for Hexagon target"));
130 static cl::opt<int> NumberScavengerSlots("number-scavenger-slots",
131 cl::Hidden, cl::desc("Set the number of scavenger slots"), cl::init(2),
134 static cl::opt<int> SpillFuncThreshold("spill-func-threshold",
135 cl::Hidden, cl::desc("Specify O2(not Os) spill func threshold"),
136 cl::init(6), cl::ZeroOrMore);
138 static cl::opt<int> SpillFuncThresholdOs("spill-func-threshold-Os",
139 cl::Hidden, cl::desc("Specify Os spill func threshold"),
140 cl::init(1), cl::ZeroOrMore);
142 static cl::opt<bool> EnableShrinkWrapping("hexagon-shrink-frame",
143 cl::init(true), cl::Hidden, cl::ZeroOrMore,
144 cl::desc("Enable stack frame shrink wrapping"));
146 static cl::opt<unsigned> ShrinkLimit("shrink-frame-limit", cl::init(UINT_MAX),
147 cl::Hidden, cl::ZeroOrMore, cl::desc("Max count of stack frame "
151 /// Map a register pair Reg to the subregister that has the greater "number",
152 /// i.e. D3 (aka R7:6) will be mapped to R7, etc.
153 unsigned getMax32BitSubRegister(unsigned Reg, const TargetRegisterInfo &TRI,
155 if (Reg < Hexagon::D0 || Reg > Hexagon::D15)
159 for (MCSubRegIterator SubRegs(Reg, &TRI); SubRegs.isValid(); ++SubRegs) {
161 if (*SubRegs > RegNo)
164 if (!RegNo || *SubRegs < RegNo)
171 /// Returns the callee saved register with the largest id in the vector.
172 unsigned getMaxCalleeSavedReg(const std::vector<CalleeSavedInfo> &CSI,
173 const TargetRegisterInfo &TRI) {
174 assert(Hexagon::R1 > 0 &&
175 "Assume physical registers are encoded as positive integers");
179 unsigned Max = getMax32BitSubRegister(CSI[0].getReg(), TRI);
180 for (unsigned I = 1, E = CSI.size(); I < E; ++I) {
181 unsigned Reg = getMax32BitSubRegister(CSI[I].getReg(), TRI);
188 /// Checks if the basic block contains any instruction that needs a stack
189 /// frame to be already in place.
190 bool needsStackFrame(const MachineBasicBlock &MBB, const BitVector &CSR) {
191 for (auto &I : MBB) {
192 const MachineInstr *MI = &I;
195 unsigned Opc = MI->getOpcode();
197 case Hexagon::ALLOCA:
198 case Hexagon::ALIGNA:
203 // Check individual operands.
204 for (ConstMIOperands Mo(MI); Mo.isValid(); ++Mo) {
205 // While the presence of a frame index does not prove that a stack
206 // frame will be required, all frame indexes should be within alloc-
207 // frame/deallocframe. Otherwise, the code that translates a frame
208 // index into an offset would have to be aware of the placement of
209 // the frame creation/destruction instructions.
214 unsigned R = Mo->getReg();
215 // Virtual registers will need scavenging, which then may require
217 if (TargetRegisterInfo::isVirtualRegister(R))
226 /// Returns true if MBB has a machine instructions that indicates a tail call
228 bool hasTailCall(const MachineBasicBlock &MBB) {
229 MachineBasicBlock::const_iterator I = MBB.getLastNonDebugInstr();
230 unsigned RetOpc = I->getOpcode();
231 return RetOpc == Hexagon::TCRETURNi || RetOpc == Hexagon::TCRETURNr;
234 /// Returns true if MBB contains an instruction that returns.
235 bool hasReturn(const MachineBasicBlock &MBB) {
236 for (auto I = MBB.getFirstTerminator(), E = MBB.end(); I != E; ++I)
244 /// Implements shrink-wrapping of the stack frame. By default, stack frame
245 /// is created in the function entry block, and is cleaned up in every block
246 /// that returns. This function finds alternate blocks: one for the frame
247 /// setup (prolog) and one for the cleanup (epilog).
248 void HexagonFrameLowering::findShrunkPrologEpilog(MachineFunction &MF,
249 MachineBasicBlock *&PrologB, MachineBasicBlock *&EpilogB) const {
250 static unsigned ShrinkCounter = 0;
252 if (ShrinkLimit.getPosition()) {
253 if (ShrinkCounter >= ShrinkLimit)
258 auto &HST = static_cast<const HexagonSubtarget&>(MF.getSubtarget());
259 auto &HRI = *HST.getRegisterInfo();
261 MachineDominatorTree MDT;
262 MDT.runOnMachineFunction(MF);
263 MachinePostDominatorTree MPT;
264 MPT.runOnMachineFunction(MF);
266 typedef DenseMap<unsigned,unsigned> UnsignedMap;
268 typedef ReversePostOrderTraversal<const MachineFunction*> RPOTType;
271 for (RPOTType::rpo_iterator I = RPOT.begin(), E = RPOT.end(); I != E; ++I)
272 RPO[(*I)->getNumber()] = RPON++;
274 // Don't process functions that have loops, at least for now. Placement
275 // of prolog and epilog must take loop structure into account. For simpli-
276 // city don't do it right now.
278 unsigned BN = RPO[I.getNumber()];
279 for (auto SI = I.succ_begin(), SE = I.succ_end(); SI != SE; ++SI) {
280 // If found a back-edge, return.
281 if (RPO[(*SI)->getNumber()] <= BN)
286 // Collect the set of blocks that need a stack frame to execute. Scan
287 // each block for uses/defs of callee-saved registers, calls, etc.
288 SmallVector<MachineBasicBlock*,16> SFBlocks;
289 BitVector CSR(Hexagon::NUM_TARGET_REGS);
290 for (const MCPhysReg *P = HRI.getCalleeSavedRegs(&MF); *P; ++P)
294 if (needsStackFrame(I, CSR))
295 SFBlocks.push_back(&I);
298 dbgs() << "Blocks needing SF: {";
299 for (auto &B : SFBlocks)
300 dbgs() << " BB#" << B->getNumber();
304 if (SFBlocks.empty())
307 // Pick a common dominator and a common post-dominator.
308 MachineBasicBlock *DomB = SFBlocks[0];
309 for (unsigned i = 1, n = SFBlocks.size(); i < n; ++i) {
310 DomB = MDT.findNearestCommonDominator(DomB, SFBlocks[i]);
314 MachineBasicBlock *PDomB = SFBlocks[0];
315 for (unsigned i = 1, n = SFBlocks.size(); i < n; ++i) {
316 PDomB = MPT.findNearestCommonDominator(PDomB, SFBlocks[i]);
321 dbgs() << "Computed dom block: BB#";
322 if (DomB) dbgs() << DomB->getNumber();
323 else dbgs() << "<null>";
324 dbgs() << ", computed pdom block: BB#";
325 if (PDomB) dbgs() << PDomB->getNumber();
326 else dbgs() << "<null>";
332 // Make sure that DomB dominates PDomB and PDomB post-dominates DomB.
333 if (!MDT.dominates(DomB, PDomB)) {
334 DEBUG(dbgs() << "Dom block does not dominate pdom block\n");
337 if (!MPT.dominates(PDomB, DomB)) {
338 DEBUG(dbgs() << "PDom block does not post-dominate dom block\n");
342 // Finally, everything seems right.
348 /// Perform most of the PEI work here:
349 /// - saving/restoring of the callee-saved registers,
350 /// - stack frame creation and destruction.
351 /// Normally, this work is distributed among various functions, but doing it
352 /// in one place allows shrink-wrapping of the stack frame.
353 void HexagonFrameLowering::emitPrologue(MachineFunction &MF) const {
354 auto &HST = static_cast<const HexagonSubtarget&>(MF.getSubtarget());
355 auto &HRI = *HST.getRegisterInfo();
357 MachineFrameInfo *MFI = MF.getFrameInfo();
358 const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
360 MachineBasicBlock *PrologB = &MF.front(), *EpilogB = nullptr;
361 if (EnableShrinkWrapping)
362 findShrunkPrologEpilog(MF, PrologB, EpilogB);
364 insertCSRSpillsInBlock(*PrologB, CSI, HRI);
365 insertPrologueInBlock(*PrologB);
368 insertCSRRestoresInBlock(*EpilogB, CSI, HRI);
369 insertEpilogueInBlock(*EpilogB);
372 if (!B.empty() && B.back().isReturn())
373 insertCSRRestoresInBlock(B, CSI, HRI);
376 if (!B.empty() && B.back().isReturn())
377 insertEpilogueInBlock(B);
382 void HexagonFrameLowering::insertPrologueInBlock(MachineBasicBlock &MBB) const {
383 MachineFunction &MF = *MBB.getParent();
384 MachineFrameInfo *MFI = MF.getFrameInfo();
385 MachineModuleInfo &MMI = MF.getMMI();
386 MachineBasicBlock::iterator MBBI = MBB.begin();
387 auto &HTM = static_cast<const HexagonTargetMachine&>(MF.getTarget());
388 auto &HST = static_cast<const HexagonSubtarget&>(MF.getSubtarget());
389 auto &HII = *HST.getInstrInfo();
390 auto &HRI = *HST.getRegisterInfo();
393 unsigned MaxAlign = std::max(MFI->getMaxAlignment(), getStackAlignment());
395 // Calculate the total stack frame size.
396 // Get the number of bytes to allocate from the FrameInfo.
397 unsigned FrameSize = MFI->getStackSize();
398 // Round up the max call frame size to the max alignment on the stack.
399 unsigned MaxCFA = RoundUpToAlignment(MFI->getMaxCallFrameSize(), MaxAlign);
400 MFI->setMaxCallFrameSize(MaxCFA);
402 FrameSize = MaxCFA + RoundUpToAlignment(FrameSize, MaxAlign);
403 MFI->setStackSize(FrameSize);
405 bool AlignStack = (MaxAlign > getStackAlignment());
407 // Check if frame moves are needed for EH.
408 bool needsFrameMoves = MMI.hasDebugInfo() ||
409 MF.getFunction()->needsUnwindTableEntry();
411 // Get the number of bytes to allocate from the FrameInfo.
412 unsigned NumBytes = MFI->getStackSize();
413 unsigned SP = HRI.getStackRegister();
414 unsigned MaxCF = MFI->getMaxCallFrameSize();
415 MachineBasicBlock::iterator InsertPt = MBB.begin();
417 auto *FuncInfo = MF.getInfo<HexagonMachineFunctionInfo>();
418 auto &AdjustRegs = FuncInfo->getAllocaAdjustInsts();
420 for (auto MI : AdjustRegs) {
421 assert((MI->getOpcode() == Hexagon::ALLOCA) && "Expected alloca");
422 expandAlloca(MI, HII, SP, MaxCF);
423 MI->eraseFromParent();
427 // Only insert ALLOCFRAME if we need to or at -O0 for the debugger. Think
428 // that this shouldn't be required, but doing so now because gcc does and
429 // gdb can't break at the start of the function without it. Will remove if
430 // this turns out to be a gdb bug.
432 bool NoOpt = (HTM.getOptLevel() == CodeGenOpt::None);
433 if (!NoOpt && !FuncInfo->hasClobberLR() && !hasFP(MF))
436 // Check for overflow.
437 // Hexagon_TODO: Ugh! hardcoding. Is there an API that can be used?
438 const unsigned int ALLOCFRAME_MAX = 16384;
440 // Create a dummy memory operand to avoid allocframe from being treated as
441 // a volatile memory reference.
442 MachineMemOperand *MMO =
443 MF.getMachineMemOperand(MachinePointerInfo(), MachineMemOperand::MOStore,
446 if (NumBytes >= ALLOCFRAME_MAX) {
447 // Emit allocframe(#0).
448 BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::S2_allocframe))
452 // Subtract offset from frame pointer.
453 // We use a caller-saved non-parameter register for that.
454 unsigned CallerSavedReg = HRI.getFirstCallerSavedNonParamReg();
455 BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::CONST32_Int_Real),
456 CallerSavedReg).addImm(NumBytes);
457 BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::A2_sub), SP)
459 .addReg(CallerSavedReg);
461 BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::S2_allocframe))
467 BuildMI(MBB, InsertPt, dl, HII.get(Hexagon::A2_andir), SP)
469 .addImm(-int64_t(MaxAlign));
472 if (needsFrameMoves) {
473 std::vector<MCCFIInstruction> Instructions = MMI.getFrameInstructions();
474 MCSymbol *FrameLabel = MMI.getContext().CreateTempSymbol();
476 // Advance CFA. DW_CFA_def_cfa
477 unsigned DwFPReg = HRI.getDwarfRegNum(HRI.getFrameRegister(), true);
478 unsigned DwRAReg = HRI.getDwarfRegNum(HRI.getRARegister(), true);
481 unsigned CFIIndex = MMI.addFrameInst(MCCFIInstruction::createDefCfa(
482 FrameLabel, DwFPReg, -8));
483 BuildMI(MBB, MBBI, dl, HII.get(TargetOpcode::CFI_INSTRUCTION))
484 .addCFIIndex(CFIIndex);
486 // R31 (return addr) = CFA - #4
487 CFIIndex = MMI.addFrameInst(MCCFIInstruction::createOffset(
488 FrameLabel, DwRAReg, -4));
489 BuildMI(MBB, MBBI, dl, HII.get(TargetOpcode::CFI_INSTRUCTION))
490 .addCFIIndex(CFIIndex);
492 // R30 (frame ptr) = CFA - #8)
493 CFIIndex = MMI.addFrameInst(MCCFIInstruction::createOffset(
494 FrameLabel, DwFPReg, -8));
495 BuildMI(MBB, MBBI, dl, HII.get(TargetOpcode::CFI_INSTRUCTION))
496 .addCFIIndex(CFIIndex);
498 unsigned int regsToMove[] = {
499 Hexagon::R1, Hexagon::R0, Hexagon::R3, Hexagon::R2,
500 Hexagon::R17, Hexagon::R16, Hexagon::R19, Hexagon::R18,
501 Hexagon::R21, Hexagon::R20, Hexagon::R23, Hexagon::R22,
502 Hexagon::R25, Hexagon::R24, Hexagon::R27, Hexagon::R26,
503 Hexagon::D0, Hexagon::D1, Hexagon::D8, Hexagon::D9, Hexagon::D10,
504 Hexagon::D11, Hexagon::D12, Hexagon::D13, Hexagon::NoRegister
507 const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
509 for (unsigned i = 0; regsToMove[i] != Hexagon::NoRegister; ++i) {
510 for (unsigned I = 0, E = CSI.size(); I < E; ++I) {
511 if (CSI[I].getReg() == regsToMove[i]) {
512 // Subtract 8 to make room for R30 and R31, which are added above.
513 int64_t Offset = getFrameIndexOffset(MF, CSI[I].getFrameIdx()) - 8;
515 if (regsToMove[i] < Hexagon::D0 || regsToMove[i] > Hexagon::D15) {
516 unsigned DwarfReg = HRI.getDwarfRegNum(regsToMove[i], true);
517 unsigned CFIIndex = MMI.addFrameInst(
518 MCCFIInstruction::createOffset(FrameLabel,
520 BuildMI(MBB, MBBI, dl, HII.get(TargetOpcode::CFI_INSTRUCTION))
521 .addCFIIndex(CFIIndex);
523 // Split the double regs into subregs, and generate appropriate
525 // The only reason, we are split double regs is, llvm-mc does not
526 // understand paired registers for cfi_offset.
527 // Eg .cfi_offset r1:0, -64
528 unsigned HiReg = getMax32BitSubRegister(regsToMove[i], HRI);
529 unsigned LoReg = getMax32BitSubRegister(regsToMove[i], HRI, false);
530 unsigned HiDwarfReg = HRI.getDwarfRegNum(HiReg, true);
531 unsigned LoDwarfReg = HRI.getDwarfRegNum(LoReg, true);
532 unsigned HiCFIIndex = MMI.addFrameInst(
533 MCCFIInstruction::createOffset(FrameLabel,
534 HiDwarfReg, Offset+4));
535 BuildMI(MBB, MBBI, dl, HII.get(TargetOpcode::CFI_INSTRUCTION))
536 .addCFIIndex(HiCFIIndex);
537 unsigned LoCFIIndex = MMI.addFrameInst(
538 MCCFIInstruction::createOffset(FrameLabel,
539 LoDwarfReg, Offset));
540 BuildMI(MBB, MBBI, dl, HII.get(TargetOpcode::CFI_INSTRUCTION))
541 .addCFIIndex(LoCFIIndex);
550 void HexagonFrameLowering::insertEpilogueInBlock(MachineBasicBlock &MBB) const {
551 MachineFunction &MF = *MBB.getParent();
553 // Only insert deallocframe if we need to. Also at -O0. See comment
554 // in insertPrologueInBlock above.
556 if (!hasFP(MF) && MF.getTarget().getOptLevel() != CodeGenOpt::None)
559 auto &HST = static_cast<const HexagonSubtarget&>(MF.getSubtarget());
560 auto &HII = *HST.getInstrInfo();
561 auto &HRI = *HST.getRegisterInfo();
562 unsigned SP = HRI.getStackRegister();
564 MachineInstr *RetI = nullptr;
565 for (auto &I : MBB) {
571 unsigned RetOpc = RetI ? RetI->getOpcode() : 0;
573 MachineBasicBlock::iterator InsertPt = MBB.getFirstTerminator();
575 if (InsertPt != MBB.end())
576 DL = InsertPt->getDebugLoc();
577 else if (!MBB.empty())
578 DL = std::prev(MBB.end())->getDebugLoc();
581 if (RetOpc == Hexagon::EH_RETURN_JMPR) {
582 BuildMI(MBB, InsertPt, DL, HII.get(Hexagon::L2_deallocframe));
583 BuildMI(MBB, InsertPt, DL, HII.get(Hexagon::A2_add), SP)
585 .addReg(Hexagon::R28);
589 // Check for RESTORE_DEALLOC_RET* tail call. Don't emit an extra dealloc-
590 // frame instruction if we encounter it.
591 if (RetOpc == Hexagon::RESTORE_DEALLOC_RET_JMP_V4) {
592 MachineBasicBlock::iterator It = RetI;
594 // Delete all instructions after the RESTORE (except labels).
595 while (It != MBB.end()) {
604 // It is possible that the restoring code is a call to a library function.
605 // All of the restore* functions include "deallocframe", so we need to make
606 // sure that we don't add an extra one.
607 bool NeedsDeallocframe = true;
608 if (!MBB.empty() && InsertPt != MBB.begin()) {
609 MachineBasicBlock::iterator PrevIt = std::prev(InsertPt);
610 unsigned COpc = PrevIt->getOpcode();
611 if (COpc == Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4)
612 NeedsDeallocframe = false;
615 if (!NeedsDeallocframe)
617 // If the returning instruction is JMPret, replace it with dealloc_return,
618 // otherwise just add deallocframe. The function could be returning via a
620 if (RetOpc != Hexagon::JMPret || DisableDeallocRet) {
621 BuildMI(MBB, InsertPt, DL, HII.get(Hexagon::L2_deallocframe));
624 unsigned NewOpc = Hexagon::L4_return;
625 MachineInstr *NewI = BuildMI(MBB, RetI, DL, HII.get(NewOpc));
626 // Transfer the function live-out registers.
627 NewI->copyImplicitOps(MF, RetI);
632 bool HexagonFrameLowering::hasFP(const MachineFunction &MF) const {
633 const MachineFrameInfo *MFI = MF.getFrameInfo();
634 const HexagonMachineFunctionInfo *FuncInfo =
635 MF.getInfo<HexagonMachineFunctionInfo>();
636 return MFI->hasCalls() || MFI->getStackSize() > 0 ||
637 FuncInfo->hasClobberLR();
648 getSpillFunctionFor(unsigned MaxReg, SpillKind SpillType) {
649 const char * V4SpillToMemoryFunctions[] = {
650 "__save_r16_through_r17",
651 "__save_r16_through_r19",
652 "__save_r16_through_r21",
653 "__save_r16_through_r23",
654 "__save_r16_through_r25",
655 "__save_r16_through_r27" };
657 const char * V4SpillFromMemoryFunctions[] = {
658 "__restore_r16_through_r17_and_deallocframe",
659 "__restore_r16_through_r19_and_deallocframe",
660 "__restore_r16_through_r21_and_deallocframe",
661 "__restore_r16_through_r23_and_deallocframe",
662 "__restore_r16_through_r25_and_deallocframe",
663 "__restore_r16_through_r27_and_deallocframe" };
665 const char * V4SpillFromMemoryTailcallFunctions[] = {
666 "__restore_r16_through_r17_and_deallocframe_before_tailcall",
667 "__restore_r16_through_r19_and_deallocframe_before_tailcall",
668 "__restore_r16_through_r21_and_deallocframe_before_tailcall",
669 "__restore_r16_through_r23_and_deallocframe_before_tailcall",
670 "__restore_r16_through_r25_and_deallocframe_before_tailcall",
671 "__restore_r16_through_r27_and_deallocframe_before_tailcall"
674 const char **SpillFunc = nullptr;
678 SpillFunc = V4SpillToMemoryFunctions;
681 SpillFunc = V4SpillFromMemoryFunctions;
683 case SK_FromMemTailcall:
684 SpillFunc = V4SpillFromMemoryTailcallFunctions;
687 assert(SpillFunc && "Unknown spill kind");
689 // Spill all callee-saved registers up to the highest register used.
704 llvm_unreachable("Unhandled maximum callee save register");
709 /// Adds all callee-saved registers up to MaxReg to the instruction.
710 static void addCalleeSaveRegistersAsImpOperand(MachineInstr *Inst,
711 unsigned MaxReg, bool IsDef) {
712 // Add the callee-saved registers as implicit uses.
713 for (unsigned R = Hexagon::R16; R <= MaxReg; ++R) {
714 MachineOperand ImpUse = MachineOperand::CreateReg(R, IsDef, true);
715 Inst->addOperand(ImpUse);
720 int HexagonFrameLowering::getFrameIndexOffset(const MachineFunction &MF,
722 return MF.getFrameInfo()->getObjectOffset(FI);
726 bool HexagonFrameLowering::insertCSRSpillsInBlock(MachineBasicBlock &MBB,
727 const CSIVect &CSI, const HexagonRegisterInfo &HRI) const {
731 MachineBasicBlock::iterator MI = MBB.begin();
732 MachineFunction &MF = *MBB.getParent();
733 const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
735 if (useSpillFunction(MF, CSI)) {
736 unsigned MaxReg = getMaxCalleeSavedReg(CSI, HRI);
737 const char *SpillFun = getSpillFunctionFor(MaxReg, SK_ToMem);
738 // Call spill function.
739 DebugLoc DL = MI != MBB.end() ? MI->getDebugLoc() : DebugLoc();
740 MachineInstr *SaveRegsCall =
741 BuildMI(MBB, MI, DL, TII.get(Hexagon::SAVE_REGISTERS_CALL_V4))
742 .addExternalSymbol(SpillFun);
743 // Add callee-saved registers as use.
744 addCalleeSaveRegistersAsImpOperand(SaveRegsCall, MaxReg, false);
745 // Add live in registers.
746 for (unsigned I = 0; I < CSI.size(); ++I)
747 MBB.addLiveIn(CSI[I].getReg());
751 for (unsigned i = 0, n = CSI.size(); i < n; ++i) {
752 unsigned Reg = CSI[i].getReg();
753 // Add live in registers. We treat eh_return callee saved register r0 - r3
754 // specially. They are not really callee saved registers as they are not
755 // supposed to be killed.
756 bool IsKill = !HRI.isEHReturnCalleeSaveReg(Reg);
757 int FI = CSI[i].getFrameIdx();
758 const TargetRegisterClass *RC = HRI.getMinimalPhysRegClass(Reg);
759 TII.storeRegToStackSlot(MBB, MI, Reg, IsKill, FI, RC, &HRI);
767 bool HexagonFrameLowering::insertCSRRestoresInBlock(MachineBasicBlock &MBB,
768 const CSIVect &CSI, const HexagonRegisterInfo &HRI) const {
772 MachineBasicBlock::iterator MI = MBB.getFirstTerminator();
773 MachineFunction &MF = *MBB.getParent();
774 const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
776 if (useRestoreFunction(MF, CSI)) {
777 bool HasTC = hasTailCall(MBB) || !hasReturn(MBB);
778 unsigned MaxR = getMaxCalleeSavedReg(CSI, HRI);
779 SpillKind Kind = HasTC ? SK_FromMemTailcall : SK_FromMem;
780 const char *RestoreFn = getSpillFunctionFor(MaxR, Kind);
782 // Call spill function.
783 DebugLoc DL = MI != MBB.end() ? MI->getDebugLoc()
784 : MBB.getLastNonDebugInstr()->getDebugLoc();
785 MachineInstr *DeallocCall = nullptr;
788 unsigned ROpc = Hexagon::RESTORE_DEALLOC_BEFORE_TAILCALL_V4;
789 DeallocCall = BuildMI(MBB, MI, DL, TII.get(ROpc))
790 .addExternalSymbol(RestoreFn);
792 // The block has a return.
793 MachineBasicBlock::iterator It = MBB.getFirstTerminator();
794 assert(It->isReturn() && std::next(It) == MBB.end());
795 unsigned ROpc = Hexagon::RESTORE_DEALLOC_RET_JMP_V4;
796 DeallocCall = BuildMI(MBB, It, DL, TII.get(ROpc))
797 .addExternalSymbol(RestoreFn);
798 // Transfer the function live-out registers.
799 DeallocCall->copyImplicitOps(MF, It);
801 addCalleeSaveRegistersAsImpOperand(DeallocCall, MaxR, true);
805 for (unsigned i = 0; i < CSI.size(); ++i) {
806 unsigned Reg = CSI[i].getReg();
807 const TargetRegisterClass *RC = HRI.getMinimalPhysRegClass(Reg);
808 int FI = CSI[i].getFrameIdx();
809 TII.loadRegFromStackSlot(MBB, MI, Reg, FI, RC, &HRI);
815 void HexagonFrameLowering::eliminateCallFramePseudoInstr(MachineFunction &MF,
816 MachineBasicBlock &MBB, MachineBasicBlock::iterator I) const {
817 MachineInstr &MI = *I;
818 unsigned Opc = MI.getOpcode();
819 (void)Opc; // Silence compiler warning.
820 assert((Opc == Hexagon::ADJCALLSTACKDOWN || Opc == Hexagon::ADJCALLSTACKUP) &&
821 "Cannot handle this call frame pseudo instruction");
826 void HexagonFrameLowering::processFunctionBeforeFrameFinalized(
827 MachineFunction &MF, RegScavenger *RS) const {
828 // If this function has uses aligned stack and also has variable sized stack
829 // objects, then we need to map all spill slots to fixed positions, so that
830 // they can be accessed through FP. Otherwise they would have to be accessed
831 // via AP, which may not be available at the particular place in the program.
832 MachineFrameInfo *MFI = MF.getFrameInfo();
833 bool HasAlloca = MFI->hasVarSizedObjects();
834 bool HasAligna = (MFI->getMaxAlignment() > getStackAlignment());
836 if (!HasAlloca || !HasAligna)
839 unsigned LFS = MFI->getLocalFrameSize();
841 for (int i = 0, e = MFI->getObjectIndexEnd(); i != e; ++i) {
842 if (!MFI->isSpillSlotObjectIndex(i) || MFI->isDeadObjectIndex(i))
844 int S = MFI->getObjectSize(i);
847 MFI->mapLocalFrameObject(i, Offset);
850 MFI->setLocalFrameSize(LFS);
851 unsigned A = MFI->getLocalFrameMaxAlign();
852 assert(A <= 8 && "Unexpected local frame alignment");
854 MFI->setLocalFrameMaxAlign(8);
855 MFI->setUseLocalStackAllocationBlock(true);
858 /// Returns true if there is no caller saved registers available.
859 static bool needToReserveScavengingSpillSlots(MachineFunction &MF,
860 const HexagonRegisterInfo &HRI) {
861 MachineRegisterInfo &MRI = MF.getRegInfo();
862 const MCPhysReg *CallerSavedRegs = HRI.getCallerSavedRegs(&MF);
863 // Check for an unused caller-saved register.
864 for ( ; *CallerSavedRegs; ++CallerSavedRegs) {
865 MCPhysReg FreeReg = *CallerSavedRegs;
866 if (MRI.isPhysRegUsed(FreeReg))
869 // Check aliased register usage.
870 bool IsCurrentRegUsed = false;
871 for (MCRegAliasIterator AI(FreeReg, &HRI, false); AI.isValid(); ++AI)
872 if (MRI.isPhysRegUsed(*AI)) {
873 IsCurrentRegUsed = true;
876 if (IsCurrentRegUsed)
879 // Neither directly used nor used through an aliased register.
882 // All caller-saved registers are used.
887 /// Replaces the predicate spill code pseudo instructions by valid instructions.
888 bool HexagonFrameLowering::replacePredRegPseudoSpillCode(MachineFunction &MF)
890 auto &HST = static_cast<const HexagonSubtarget&>(MF.getSubtarget());
891 auto &HII = *HST.getInstrInfo();
892 MachineRegisterInfo &MRI = MF.getRegInfo();
893 bool HasReplacedPseudoInst = false;
894 // Replace predicate spill pseudo instructions by real code.
895 // Loop over all of the basic blocks.
896 for (MachineFunction::iterator MBBb = MF.begin(), MBBe = MF.end();
897 MBBb != MBBe; ++MBBb) {
898 MachineBasicBlock* MBB = MBBb;
899 // Traverse the basic block.
900 MachineBasicBlock::iterator NextII;
901 for (MachineBasicBlock::iterator MII = MBB->begin(); MII != MBB->end();
903 MachineInstr *MI = MII;
904 NextII = std::next(MII);
905 int Opc = MI->getOpcode();
906 if (Opc == Hexagon::STriw_pred) {
907 HasReplacedPseudoInst = true;
908 // STriw_pred FI, 0, SrcReg;
909 unsigned VirtReg = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
910 unsigned SrcReg = MI->getOperand(2).getReg();
911 bool IsOrigSrcRegKilled = MI->getOperand(2).isKill();
913 assert(MI->getOperand(0).isFI() && "Expect a frame index");
914 assert(Hexagon::PredRegsRegClass.contains(SrcReg) &&
915 "Not a predicate register");
917 // Insert transfer to general purpose register.
918 // VirtReg = C2_tfrpr SrcPredReg
919 BuildMI(*MBB, MII, MI->getDebugLoc(), HII.get(Hexagon::C2_tfrpr),
920 VirtReg).addReg(SrcReg, getKillRegState(IsOrigSrcRegKilled));
922 // Change instruction to S2_storeri_io.
923 // S2_storeri_io FI, 0, VirtReg
924 MI->setDesc(HII.get(Hexagon::S2_storeri_io));
925 MI->getOperand(2).setReg(VirtReg);
926 MI->getOperand(2).setIsKill();
928 } else if (Opc == Hexagon::LDriw_pred) {
929 // DstReg = LDriw_pred FI, 0
930 MachineOperand &M0 = MI->getOperand(0);
936 unsigned VirtReg = MRI.createVirtualRegister(&Hexagon::IntRegsRegClass);
937 unsigned DestReg = MI->getOperand(0).getReg();
939 assert(MI->getOperand(1).isFI() && "Expect a frame index");
940 assert(Hexagon::PredRegsRegClass.contains(DestReg) &&
941 "Not a predicate register");
943 // Change instruction to L2_loadri_io.
944 // VirtReg = L2_loadri_io FI, 0
945 MI->setDesc(HII.get(Hexagon::L2_loadri_io));
946 MI->getOperand(0).setReg(VirtReg);
948 // Insert transfer to general purpose register.
949 // DestReg = C2_tfrrp VirtReg
950 const MCInstrDesc &D = HII.get(Hexagon::C2_tfrrp);
951 BuildMI(*MBB, std::next(MII), MI->getDebugLoc(), D, DestReg)
952 .addReg(VirtReg, getKillRegState(true));
953 HasReplacedPseudoInst = true;
957 return HasReplacedPseudoInst;
961 void HexagonFrameLowering::processFunctionBeforeCalleeSavedScan(
962 MachineFunction &MF, RegScavenger* RS) const {
963 auto &HST = static_cast<const HexagonSubtarget&>(MF.getSubtarget());
964 auto &HRI = *HST.getRegisterInfo();
966 bool HasEHReturn = MF.getInfo<HexagonMachineFunctionInfo>()->hasEHReturn();
968 // If we have a function containing __builtin_eh_return we want to spill and
969 // restore all callee saved registers. Pretend that they are used.
971 MachineRegisterInfo &MRI = MF.getRegInfo();
972 for (const MCPhysReg *CSRegs = HRI.getCalleeSavedRegs(&MF); *CSRegs;
974 if (!MRI.isPhysRegUsed(*CSRegs))
975 MRI.setPhysRegUsed(*CSRegs);
978 const TargetRegisterClass &RC = Hexagon::IntRegsRegClass;
980 // Replace predicate register pseudo spill code.
981 bool HasReplacedPseudoInst = replacePredRegPseudoSpillCode(MF);
983 // We need to reserve a a spill slot if scavenging could potentially require
984 // spilling a scavenged register.
985 if (HasReplacedPseudoInst && needToReserveScavengingSpillSlots(MF, HRI)) {
986 MachineFrameInfo *MFI = MF.getFrameInfo();
987 for (int i=0; i < NumberScavengerSlots; i++)
988 RS->addScavengingFrameIndex(
989 MFI->CreateSpillStackObject(RC.getSize(), RC.getAlignment()));
995 static void dump_registers(BitVector &Regs, const TargetRegisterInfo &TRI) {
997 for (int x = Regs.find_first(); x >= 0; x = Regs.find_next(x)) {
999 dbgs() << ' ' << PrintReg(R, &TRI);
1006 bool HexagonFrameLowering::assignCalleeSavedSpillSlots(MachineFunction &MF,
1007 const TargetRegisterInfo *TRI, std::vector<CalleeSavedInfo> &CSI) const {
1008 DEBUG(dbgs() << LLVM_FUNCTION_NAME << " on "
1009 << MF.getFunction().getName() << '\n');
1010 MachineFrameInfo *MFI = MF.getFrameInfo();
1011 BitVector SRegs(Hexagon::NUM_TARGET_REGS);
1013 // Generate a set of unique, callee-saved registers (SRegs), where each
1014 // register in the set is maximal in terms of sub-/super-register relation,
1015 // i.e. for each R in SRegs, no proper super-register of R is also in SRegs.
1017 // (1) For each callee-saved register, add that register and all of its
1018 // sub-registers to SRegs.
1019 DEBUG(dbgs() << "Initial CS registers: {");
1020 for (unsigned i = 0, n = CSI.size(); i < n; ++i) {
1021 unsigned R = CSI[i].getReg();
1022 DEBUG(dbgs() << ' ' << PrintReg(R, TRI));
1023 for (MCSubRegIterator SR(R, TRI, true); SR.isValid(); ++SR)
1026 DEBUG(dbgs() << " }\n");
1027 DEBUG(dbgs() << "SRegs.1: "; dump_registers(SRegs, *TRI); dbgs() << "\n");
1029 // (2) For each reserved register, remove that register and all of its
1030 // sub- and super-registers from SRegs.
1031 BitVector Reserved = TRI->getReservedRegs(MF);
1032 for (int x = Reserved.find_first(); x >= 0; x = Reserved.find_next(x)) {
1034 for (MCSuperRegIterator SR(R, TRI, true); SR.isValid(); ++SR)
1037 DEBUG(dbgs() << "Res: "; dump_registers(Reserved, *TRI); dbgs() << "\n");
1038 DEBUG(dbgs() << "SRegs.2: "; dump_registers(SRegs, *TRI); dbgs() << "\n");
1040 // (3) Collect all registers that have at least one sub-register in SRegs,
1041 // and also have no sub-registers that are reserved. These will be the can-
1042 // didates for saving as a whole instead of their individual sub-registers.
1043 // (Saving R17:16 instead of R16 is fine, but only if R17 was not reserved.)
1044 BitVector TmpSup(Hexagon::NUM_TARGET_REGS);
1045 for (int x = SRegs.find_first(); x >= 0; x = SRegs.find_next(x)) {
1047 for (MCSuperRegIterator SR(R, TRI); SR.isValid(); ++SR)
1050 for (int x = TmpSup.find_first(); x >= 0; x = TmpSup.find_next(x)) {
1052 for (MCSubRegIterator SR(R, TRI, true); SR.isValid(); ++SR) {
1059 DEBUG(dbgs() << "TmpSup: "; dump_registers(TmpSup, *TRI); dbgs() << "\n");
1061 // (4) Include all super-registers found in (3) into SRegs.
1063 DEBUG(dbgs() << "SRegs.4: "; dump_registers(SRegs, *TRI); dbgs() << "\n");
1065 // (5) For each register R in SRegs, if any super-register of R is in SRegs,
1066 // remove R from SRegs.
1067 for (int x = SRegs.find_first(); x >= 0; x = SRegs.find_next(x)) {
1069 for (MCSuperRegIterator SR(R, TRI); SR.isValid(); ++SR) {
1076 DEBUG(dbgs() << "SRegs.5: "; dump_registers(SRegs, *TRI); dbgs() << "\n");
1078 // Now, for each register that has a fixed stack slot, create the stack
1082 typedef TargetFrameLowering::SpillSlot SpillSlot;
1084 int MinOffset = 0; // CS offsets are negative.
1085 const SpillSlot *FixedSlots = getCalleeSavedSpillSlots(NumFixed);
1086 for (const SpillSlot *S = FixedSlots; S != FixedSlots+NumFixed; ++S) {
1089 const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(S->Reg);
1090 int FI = MFI->CreateFixedSpillStackObject(RC->getSize(), S->Offset);
1091 MinOffset = std::min(MinOffset, S->Offset);
1092 CSI.push_back(CalleeSavedInfo(S->Reg, FI));
1093 SRegs[S->Reg] = false;
1096 // There can be some registers that don't have fixed slots. For example,
1097 // we need to store R0-R3 in functions with exception handling. For each
1098 // such register, create a non-fixed stack object.
1099 for (int x = SRegs.find_first(); x >= 0; x = SRegs.find_next(x)) {
1101 const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(R);
1102 int Off = MinOffset - RC->getSize();
1103 unsigned Align = std::min(RC->getAlignment(), getStackAlignment());
1104 assert(isPowerOf2_32(Align));
1106 int FI = MFI->CreateFixedSpillStackObject(RC->getSize(), Off);
1107 MinOffset = std::min(MinOffset, Off);
1108 CSI.push_back(CalleeSavedInfo(R, FI));
1113 dbgs() << "CS information: {";
1114 for (unsigned i = 0, n = CSI.size(); i < n; ++i) {
1115 int FI = CSI[i].getFrameIdx();
1116 int Off = MFI->getObjectOffset(FI);
1117 dbgs() << ' ' << PrintReg(CSI[i].getReg(), TRI) << ":fi#" << FI << ":sp";
1126 // Verify that all registers were handled.
1127 bool MissedReg = false;
1128 for (int x = SRegs.find_first(); x >= 0; x = SRegs.find_next(x)) {
1130 dbgs() << PrintReg(R, TRI) << ' ';
1134 llvm_unreachable("...there are unhandled callee-saved registers!");
1141 void HexagonFrameLowering::expandAlloca(MachineInstr *AI,
1142 const HexagonInstrInfo &HII, unsigned SP, unsigned CF) const {
1143 MachineBasicBlock &MB = *AI->getParent();
1144 DebugLoc DL = AI->getDebugLoc();
1145 unsigned A = AI->getOperand(2).getImm();
1148 // Rd = alloca Rs, #A
1150 // If Rs and Rd are different registers, use this sequence:
1151 // Rd = sub(r29, Rs)
1152 // r29 = sub(r29, Rs)
1153 // Rd = and(Rd, #-A) ; if necessary
1154 // r29 = and(r29, #-A) ; if necessary
1155 // Rd = add(Rd, #CF) ; CF size aligned to at most A
1157 // Rd = sub(r29, Rs)
1158 // Rd = and(Rd, #-A) ; if necessary
1160 // Rd = add(Rd, #CF) ; CF size aligned to at most A
1162 MachineOperand &RdOp = AI->getOperand(0);
1163 MachineOperand &RsOp = AI->getOperand(1);
1164 unsigned Rd = RdOp.getReg(), Rs = RsOp.getReg();
1166 // Rd = sub(r29, Rs)
1167 BuildMI(MB, AI, DL, HII.get(Hexagon::A2_sub), Rd)
1171 // r29 = sub(r29, Rs)
1172 BuildMI(MB, AI, DL, HII.get(Hexagon::A2_sub), SP)
1177 // Rd = and(Rd, #-A)
1178 BuildMI(MB, AI, DL, HII.get(Hexagon::A2_andir), Rd)
1180 .addImm(-int64_t(A));
1182 BuildMI(MB, AI, DL, HII.get(Hexagon::A2_andir), SP)
1184 .addImm(-int64_t(A));
1188 BuildMI(MB, AI, DL, HII.get(TargetOpcode::COPY), SP)
1192 // Rd = add(Rd, #CF)
1193 BuildMI(MB, AI, DL, HII.get(Hexagon::A2_addi), Rd)
1200 bool HexagonFrameLowering::needsAligna(const MachineFunction &MF) const {
1201 const MachineFrameInfo *MFI = MF.getFrameInfo();
1202 if (!MFI->hasVarSizedObjects())
1204 unsigned MaxA = MFI->getMaxAlignment();
1205 if (MaxA <= getStackAlignment())
1211 MachineInstr *HexagonFrameLowering::getAlignaInstr(MachineFunction &MF) const {
1214 if (I.getOpcode() == Hexagon::ALIGNA)
1220 inline static bool isOptSize(const MachineFunction &MF) {
1221 AttributeSet AF = MF.getFunction()->getAttributes();
1222 return AF.hasAttribute(AttributeSet::FunctionIndex,
1223 Attribute::OptimizeForSize);
1226 inline static bool isMinSize(const MachineFunction &MF) {
1227 AttributeSet AF = MF.getFunction()->getAttributes();
1228 return AF.hasAttribute(AttributeSet::FunctionIndex, Attribute::MinSize);
1232 /// Determine whether the callee-saved register saves and restores should
1233 /// be generated via inline code. If this function returns "true", inline
1234 /// code will be generated. If this function returns "false", additional
1235 /// checks are performed, which may still lead to the inline code.
1236 bool HexagonFrameLowering::shouldInlineCSR(MachineFunction &MF,
1237 const CSIVect &CSI) const {
1238 if (MF.getInfo<HexagonMachineFunctionInfo>()->hasEHReturn())
1240 if (!isOptSize(MF) && !isMinSize(MF))
1241 if (MF.getTarget().getOptLevel() > CodeGenOpt::Default)
1244 // Check if CSI only has double registers, and if the registers form
1245 // a contiguous block starting from D8.
1246 BitVector Regs(Hexagon::NUM_TARGET_REGS);
1247 for (unsigned i = 0, n = CSI.size(); i < n; ++i) {
1248 unsigned R = CSI[i].getReg();
1249 if (!Hexagon::DoubleRegsRegClass.contains(R))
1253 int F = Regs.find_first();
1254 if (F != Hexagon::D8)
1257 int N = Regs.find_next(F);
1258 if (N >= 0 && N != F+1)
1267 bool HexagonFrameLowering::useSpillFunction(MachineFunction &MF,
1268 const CSIVect &CSI) const {
1269 if (shouldInlineCSR(MF, CSI))
1271 unsigned NumCSI = CSI.size();
1275 unsigned Threshold = isOptSize(MF) ? SpillFuncThresholdOs
1276 : SpillFuncThreshold;
1277 return Threshold < NumCSI;
1281 bool HexagonFrameLowering::useRestoreFunction(MachineFunction &MF,
1282 const CSIVect &CSI) const {
1283 if (shouldInlineCSR(MF, CSI))
1285 unsigned NumCSI = CSI.size();
1286 unsigned Threshold = isOptSize(MF) ? SpillFuncThresholdOs-1
1287 : SpillFuncThreshold;
1288 return Threshold < NumCSI;