1 //===-- X86FrameLowering.cpp - X86 Frame 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 X86 implementation of TargetFrameLowering class.
12 //===----------------------------------------------------------------------===//
14 #include "X86FrameLowering.h"
15 #include "X86InstrBuilder.h"
16 #include "X86InstrInfo.h"
17 #include "X86MachineFunctionInfo.h"
18 #include "X86Subtarget.h"
19 #include "X86TargetMachine.h"
20 #include "llvm/ADT/SmallSet.h"
21 #include "llvm/CodeGen/MachineFrameInfo.h"
22 #include "llvm/CodeGen/MachineFunction.h"
23 #include "llvm/CodeGen/MachineInstrBuilder.h"
24 #include "llvm/CodeGen/MachineModuleInfo.h"
25 #include "llvm/CodeGen/MachineRegisterInfo.h"
26 #include "llvm/IR/DataLayout.h"
27 #include "llvm/IR/Function.h"
28 #include "llvm/MC/MCAsmInfo.h"
29 #include "llvm/MC/MCSymbol.h"
30 #include "llvm/Support/CommandLine.h"
31 #include "llvm/Target/TargetOptions.h"
32 #include "llvm/Support/Debug.h"
37 // FIXME: completely move here.
38 extern cl::opt<bool> ForceStackAlign;
40 bool X86FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const {
41 return !MF.getFrameInfo()->hasVarSizedObjects() &&
42 !MF.getInfo<X86MachineFunctionInfo>()->getHasPushSequences();
45 /// canSimplifyCallFramePseudos - If there is a reserved call frame, the
46 /// call frame pseudos can be simplified. Having a FP, as in the default
47 /// implementation, is not sufficient here since we can't always use it.
48 /// Use a more nuanced condition.
50 X86FrameLowering::canSimplifyCallFramePseudos(const MachineFunction &MF) const {
51 const X86RegisterInfo *TRI = static_cast<const X86RegisterInfo *>
52 (MF.getSubtarget().getRegisterInfo());
53 return hasReservedCallFrame(MF) ||
54 (hasFP(MF) && !TRI->needsStackRealignment(MF))
55 || TRI->hasBasePointer(MF);
58 // needsFrameIndexResolution - Do we need to perform FI resolution for
59 // this function. Normally, this is required only when the function
60 // has any stack objects. However, FI resolution actually has another job,
61 // not apparent from the title - it resolves callframesetup/destroy
62 // that were not simplified earlier.
63 // So, this is required for x86 functions that have push sequences even
64 // when there are no stack objects.
66 X86FrameLowering::needsFrameIndexResolution(const MachineFunction &MF) const {
67 return MF.getFrameInfo()->hasStackObjects() ||
68 MF.getInfo<X86MachineFunctionInfo>()->getHasPushSequences();
71 /// hasFP - Return true if the specified function should have a dedicated frame
72 /// pointer register. This is true if the function has variable sized allocas
73 /// or if frame pointer elimination is disabled.
74 bool X86FrameLowering::hasFP(const MachineFunction &MF) const {
75 const MachineFrameInfo *MFI = MF.getFrameInfo();
76 const MachineModuleInfo &MMI = MF.getMMI();
77 const TargetRegisterInfo *RegInfo = MF.getSubtarget().getRegisterInfo();
79 return (MF.getTarget().Options.DisableFramePointerElim(MF) ||
80 RegInfo->needsStackRealignment(MF) ||
81 MFI->hasVarSizedObjects() ||
82 MFI->isFrameAddressTaken() || MFI->hasInlineAsmWithSPAdjust() ||
83 MF.getInfo<X86MachineFunctionInfo>()->getForceFramePointer() ||
84 MMI.callsUnwindInit() || MMI.callsEHReturn() ||
85 MFI->hasStackMap() || MFI->hasPatchPoint());
88 static unsigned getSUBriOpcode(unsigned IsLP64, int64_t Imm) {
92 return X86::SUB64ri32;
100 static unsigned getADDriOpcode(unsigned IsLP64, int64_t Imm) {
103 return X86::ADD64ri8;
104 return X86::ADD64ri32;
107 return X86::ADD32ri8;
112 static unsigned getSUBrrOpcode(unsigned isLP64) {
113 return isLP64 ? X86::SUB64rr : X86::SUB32rr;
116 static unsigned getADDrrOpcode(unsigned isLP64) {
117 return isLP64 ? X86::ADD64rr : X86::ADD32rr;
120 static unsigned getANDriOpcode(bool IsLP64, int64_t Imm) {
123 return X86::AND64ri8;
124 return X86::AND64ri32;
127 return X86::AND32ri8;
131 static unsigned getLEArOpcode(unsigned IsLP64) {
132 return IsLP64 ? X86::LEA64r : X86::LEA32r;
135 /// findDeadCallerSavedReg - Return a caller-saved register that isn't live
136 /// when it reaches the "return" instruction. We can then pop a stack object
137 /// to this register without worry about clobbering it.
138 static unsigned findDeadCallerSavedReg(MachineBasicBlock &MBB,
139 MachineBasicBlock::iterator &MBBI,
140 const TargetRegisterInfo &TRI,
142 const MachineFunction *MF = MBB.getParent();
143 const Function *F = MF->getFunction();
144 if (!F || MF->getMMI().callsEHReturn())
147 static const uint16_t CallerSavedRegs32Bit[] = {
148 X86::EAX, X86::EDX, X86::ECX, 0
151 static const uint16_t CallerSavedRegs64Bit[] = {
152 X86::RAX, X86::RDX, X86::RCX, X86::RSI, X86::RDI,
153 X86::R8, X86::R9, X86::R10, X86::R11, 0
156 unsigned Opc = MBBI->getOpcode();
163 case X86::TCRETURNdi:
164 case X86::TCRETURNri:
165 case X86::TCRETURNmi:
166 case X86::TCRETURNdi64:
167 case X86::TCRETURNri64:
168 case X86::TCRETURNmi64:
170 case X86::EH_RETURN64: {
171 SmallSet<uint16_t, 8> Uses;
172 for (unsigned i = 0, e = MBBI->getNumOperands(); i != e; ++i) {
173 MachineOperand &MO = MBBI->getOperand(i);
174 if (!MO.isReg() || MO.isDef())
176 unsigned Reg = MO.getReg();
179 for (MCRegAliasIterator AI(Reg, &TRI, true); AI.isValid(); ++AI)
183 const uint16_t *CS = Is64Bit ? CallerSavedRegs64Bit : CallerSavedRegs32Bit;
185 if (!Uses.count(*CS))
193 static bool isEAXLiveIn(MachineFunction &MF) {
194 for (MachineRegisterInfo::livein_iterator II = MF.getRegInfo().livein_begin(),
195 EE = MF.getRegInfo().livein_end(); II != EE; ++II) {
196 unsigned Reg = II->first;
198 if (Reg == X86::RAX || Reg == X86::EAX || Reg == X86::AX ||
199 Reg == X86::AH || Reg == X86::AL)
206 /// emitSPUpdate - Emit a series of instructions to increment / decrement the
207 /// stack pointer by a constant value.
209 void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
210 unsigned StackPtr, int64_t NumBytes,
211 bool Is64BitTarget, bool Is64BitStackPtr, bool UseLEA,
212 const TargetInstrInfo &TII, const TargetRegisterInfo &TRI) {
213 bool isSub = NumBytes < 0;
214 uint64_t Offset = isSub ? -NumBytes : NumBytes;
217 Opc = getLEArOpcode(Is64BitStackPtr);
220 ? getSUBriOpcode(Is64BitStackPtr, Offset)
221 : getADDriOpcode(Is64BitStackPtr, Offset);
223 uint64_t Chunk = (1LL << 31) - 1;
224 DebugLoc DL = MBB.findDebugLoc(MBBI);
227 if (Offset > Chunk) {
228 // Rather than emit a long series of instructions for large offsets,
229 // load the offset into a register and do one sub/add
232 if (isSub && !isEAXLiveIn(*MBB.getParent()))
233 Reg = (unsigned)(Is64BitTarget ? X86::RAX : X86::EAX);
235 Reg = findDeadCallerSavedReg(MBB, MBBI, TRI, Is64BitTarget);
238 Opc = Is64BitTarget ? X86::MOV64ri : X86::MOV32ri;
239 BuildMI(MBB, MBBI, DL, TII.get(Opc), Reg)
242 ? getSUBrrOpcode(Is64BitTarget)
243 : getADDrrOpcode(Is64BitTarget);
244 MachineInstr *MI = BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr)
247 MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead.
253 uint64_t ThisVal = std::min(Offset, Chunk);
254 if (ThisVal == (Is64BitTarget ? 8 : 4)) {
255 // Use push / pop instead.
257 ? (unsigned)(Is64BitTarget ? X86::RAX : X86::EAX)
258 : findDeadCallerSavedReg(MBB, MBBI, TRI, Is64BitTarget);
261 ? (Is64BitTarget ? X86::PUSH64r : X86::PUSH32r)
262 : (Is64BitTarget ? X86::POP64r : X86::POP32r);
263 MachineInstr *MI = BuildMI(MBB, MBBI, DL, TII.get(Opc))
264 .addReg(Reg, getDefRegState(!isSub) | getUndefRegState(isSub));
266 MI->setFlag(MachineInstr::FrameSetup);
272 MachineInstr *MI = nullptr;
275 MI = addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr),
276 StackPtr, false, isSub ? -ThisVal : ThisVal);
278 MI = BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr)
281 MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead.
285 MI->setFlag(MachineInstr::FrameSetup);
291 /// mergeSPUpdatesUp - Merge two stack-manipulating instructions upper iterator.
293 void mergeSPUpdatesUp(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
294 unsigned StackPtr, uint64_t *NumBytes = nullptr) {
295 if (MBBI == MBB.begin()) return;
297 MachineBasicBlock::iterator PI = std::prev(MBBI);
298 unsigned Opc = PI->getOpcode();
299 if ((Opc == X86::ADD64ri32 || Opc == X86::ADD64ri8 ||
300 Opc == X86::ADD32ri || Opc == X86::ADD32ri8 ||
301 Opc == X86::LEA32r || Opc == X86::LEA64_32r) &&
302 PI->getOperand(0).getReg() == StackPtr) {
304 *NumBytes += PI->getOperand(2).getImm();
306 } else if ((Opc == X86::SUB64ri32 || Opc == X86::SUB64ri8 ||
307 Opc == X86::SUB32ri || Opc == X86::SUB32ri8) &&
308 PI->getOperand(0).getReg() == StackPtr) {
310 *NumBytes -= PI->getOperand(2).getImm();
315 /// mergeSPUpdates - Checks the instruction before/after the passed
316 /// instruction. If it is an ADD/SUB/LEA instruction it is deleted argument and
317 /// the stack adjustment is returned as a positive value for ADD/LEA and a
318 /// negative for SUB.
319 static int mergeSPUpdates(MachineBasicBlock &MBB,
320 MachineBasicBlock::iterator &MBBI, unsigned StackPtr,
321 bool doMergeWithPrevious) {
322 if ((doMergeWithPrevious && MBBI == MBB.begin()) ||
323 (!doMergeWithPrevious && MBBI == MBB.end()))
326 MachineBasicBlock::iterator PI = doMergeWithPrevious ? std::prev(MBBI) : MBBI;
327 MachineBasicBlock::iterator NI = doMergeWithPrevious ? nullptr
329 unsigned Opc = PI->getOpcode();
332 if ((Opc == X86::ADD64ri32 || Opc == X86::ADD64ri8 ||
333 Opc == X86::ADD32ri || Opc == X86::ADD32ri8 ||
334 Opc == X86::LEA32r || Opc == X86::LEA64_32r) &&
335 PI->getOperand(0).getReg() == StackPtr){
336 Offset += PI->getOperand(2).getImm();
338 if (!doMergeWithPrevious) MBBI = NI;
339 } else if ((Opc == X86::SUB64ri32 || Opc == X86::SUB64ri8 ||
340 Opc == X86::SUB32ri || Opc == X86::SUB32ri8) &&
341 PI->getOperand(0).getReg() == StackPtr) {
342 Offset -= PI->getOperand(2).getImm();
344 if (!doMergeWithPrevious) MBBI = NI;
351 X86FrameLowering::emitCalleeSavedFrameMoves(MachineBasicBlock &MBB,
352 MachineBasicBlock::iterator MBBI,
354 MachineFunction &MF = *MBB.getParent();
355 MachineFrameInfo *MFI = MF.getFrameInfo();
356 MachineModuleInfo &MMI = MF.getMMI();
357 const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo();
358 const TargetInstrInfo &TII = *MF.getSubtarget().getInstrInfo();
360 // Add callee saved registers to move list.
361 const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
362 if (CSI.empty()) return;
364 // Calculate offsets.
365 for (std::vector<CalleeSavedInfo>::const_iterator
366 I = CSI.begin(), E = CSI.end(); I != E; ++I) {
367 int64_t Offset = MFI->getObjectOffset(I->getFrameIdx());
368 unsigned Reg = I->getReg();
370 unsigned DwarfReg = MRI->getDwarfRegNum(Reg, true);
372 MMI.addFrameInst(MCCFIInstruction::createOffset(nullptr, DwarfReg,
374 BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::CFI_INSTRUCTION))
375 .addCFIIndex(CFIIndex);
379 /// usesTheStack - This function checks if any of the users of EFLAGS
380 /// copies the EFLAGS. We know that the code that lowers COPY of EFLAGS has
381 /// to use the stack, and if we don't adjust the stack we clobber the first
383 /// See X86InstrInfo::copyPhysReg.
384 static bool usesTheStack(const MachineFunction &MF) {
385 const MachineRegisterInfo &MRI = MF.getRegInfo();
387 for (MachineRegisterInfo::reg_instr_iterator
388 ri = MRI.reg_instr_begin(X86::EFLAGS), re = MRI.reg_instr_end();
396 void X86FrameLowering::emitStackProbeCall(MachineFunction &MF,
397 MachineBasicBlock &MBB,
398 MachineBasicBlock::iterator MBBI,
400 const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
401 const TargetInstrInfo &TII = *STI.getInstrInfo();
402 bool Is64Bit = STI.is64Bit();
403 bool IsLargeCodeModel = MF.getTarget().getCodeModel() == CodeModel::Large;
407 CallOp = IsLargeCodeModel ? X86::CALL64r : X86::CALL64pcrel32;
409 CallOp = X86::CALLpcrel32;
413 if (STI.isTargetCygMing()) {
414 Symbol = "___chkstk_ms";
418 } else if (STI.isTargetCygMing())
423 MachineInstrBuilder CI;
425 // All current stack probes take AX and SP as input, clobber flags, and
426 // preserve all registers. x86_64 probes leave RSP unmodified.
427 if (Is64Bit && MF.getTarget().getCodeModel() == CodeModel::Large) {
428 // For the large code model, we have to call through a register. Use R11,
429 // as it is scratch in all supported calling conventions.
430 BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64ri), X86::R11)
431 .addExternalSymbol(Symbol);
432 CI = BuildMI(MBB, MBBI, DL, TII.get(CallOp)).addReg(X86::R11);
434 CI = BuildMI(MBB, MBBI, DL, TII.get(CallOp)).addExternalSymbol(Symbol);
437 unsigned AX = Is64Bit ? X86::RAX : X86::EAX;
438 unsigned SP = Is64Bit ? X86::RSP : X86::ESP;
439 CI.addReg(AX, RegState::Implicit)
440 .addReg(SP, RegState::Implicit)
441 .addReg(AX, RegState::Define | RegState::Implicit)
442 .addReg(SP, RegState::Define | RegState::Implicit)
443 .addReg(X86::EFLAGS, RegState::Define | RegState::Implicit);
446 // MSVC x64's __chkstk and cygwin/mingw's ___chkstk_ms do not adjust %rsp
447 // themselves. It also does not clobber %rax so we can reuse it when
449 BuildMI(MBB, MBBI, DL, TII.get(X86::SUB64rr), X86::RSP)
455 static unsigned calculateSetFPREG(uint64_t SPAdjust) {
456 // Win64 ABI has a less restrictive limitation of 240; 128 works equally well
457 // and might require smaller successive adjustments.
458 const uint64_t Win64MaxSEHOffset = 128;
459 uint64_t SEHFrameOffset = std::min(SPAdjust, Win64MaxSEHOffset);
460 // Win64 ABI requires 16-byte alignment for the UWOP_SET_FPREG opcode.
461 return SEHFrameOffset & -16;
464 // If we're forcing a stack realignment we can't rely on just the frame
465 // info, we need to know the ABI stack alignment as well in case we
466 // have a call out. Otherwise just make sure we have some alignment - we'll
467 // go with the minimum SlotSize.
468 static uint64_t calculateMaxStackAlign(const MachineFunction &MF) {
469 const MachineFrameInfo *MFI = MF.getFrameInfo();
470 uint64_t MaxAlign = MFI->getMaxAlignment(); // Desired stack alignment.
471 const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
472 const X86RegisterInfo *RegInfo = STI.getRegisterInfo();
473 unsigned SlotSize = RegInfo->getSlotSize();
474 unsigned StackAlign = STI.getFrameLowering()->getStackAlignment();
475 if (ForceStackAlign) {
477 MaxAlign = (StackAlign > MaxAlign) ? StackAlign : MaxAlign;
478 else if (MaxAlign < SlotSize)
484 /// emitPrologue - Push callee-saved registers onto the stack, which
485 /// automatically adjust the stack pointer. Adjust the stack pointer to allocate
486 /// space for local variables. Also emit labels used by the exception handler to
487 /// generate the exception handling frames.
490 Here's a gist of what gets emitted:
492 ; Establish frame pointer, if needed
495 .cfi_def_cfa_offset 16
496 .cfi_offset %rbp, -16
499 .cfi_def_cfa_register %rbp
501 ; Spill general-purpose registers
502 [for all callee-saved GPRs]
505 .cfi_def_cfa_offset (offset from RETADDR)
508 ; If the required stack alignment > default stack alignment
509 ; rsp needs to be re-aligned. This creates a "re-alignment gap"
510 ; of unknown size in the stack frame.
511 [if stack needs re-alignment]
514 ; Allocate space for locals
515 [if target is Windows and allocated space > 4096 bytes]
516 ; Windows needs special care for allocations larger
519 call ___chkstk_ms/___chkstk
525 .seh_stackalloc (size of XMM spill slots)
526 .seh_setframe %rbp, SEHFrameOffset ; = size of all spill slots
531 ; Note, that while only Windows 64 ABI specifies XMMs as callee-preserved,
532 ; they may get spilled on any platform, if the current function
533 ; calls @llvm.eh.unwind.init
535 [for all callee-saved XMM registers]
536 movaps %<xmm reg>, -MMM(%rbp)
537 [for all callee-saved XMM registers]
538 .seh_savexmm %<xmm reg>, (-MMM + SEHFrameOffset)
539 ; i.e. the offset relative to (%rbp - SEHFrameOffset)
541 [for all callee-saved XMM registers]
542 movaps %<xmm reg>, KKK(%rsp)
543 [for all callee-saved XMM registers]
544 .seh_savexmm %<xmm reg>, KKK
548 [if needs base pointer]
550 [if needs to restore base pointer]
555 [for all callee-saved registers]
556 .cfi_offset %<reg>, (offset from %rbp)
558 .cfi_def_cfa_offset (offset from RETADDR)
559 [for all callee-saved registers]
560 .cfi_offset %<reg>, (offset from %rsp)
563 - .seh directives are emitted only for Windows 64 ABI
564 - .cfi directives are emitted for all other ABIs
565 - for 32-bit code, substitute %e?? registers for %r??
568 void X86FrameLowering::emitPrologue(MachineFunction &MF) const {
569 MachineBasicBlock &MBB = MF.front(); // Prologue goes in entry BB.
570 MachineBasicBlock::iterator MBBI = MBB.begin();
571 MachineFrameInfo *MFI = MF.getFrameInfo();
572 const Function *Fn = MF.getFunction();
573 const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
574 const X86RegisterInfo *RegInfo = STI.getRegisterInfo();
575 const TargetInstrInfo &TII = *STI.getInstrInfo();
576 MachineModuleInfo &MMI = MF.getMMI();
577 X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
578 uint64_t MaxAlign = calculateMaxStackAlign(MF); // Desired stack alignment.
579 uint64_t StackSize = MFI->getStackSize(); // Number of bytes to allocate.
580 bool HasFP = hasFP(MF);
581 bool Is64Bit = STI.is64Bit();
582 // standard x86_64 and NaCl use 64-bit frame/stack pointers, x32 - 32-bit.
583 const bool Uses64BitFramePtr = STI.isTarget64BitLP64() || STI.isTargetNaCl64();
584 bool IsWin64 = STI.isTargetWin64();
585 // Not necessarily synonymous with IsWin64.
586 bool IsWinEH = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
587 bool NeedsWinEH = IsWinEH && Fn->needsUnwindTableEntry();
589 !IsWinEH && (MMI.hasDebugInfo() || Fn->needsUnwindTableEntry());
590 bool UseLEA = STI.useLeaForSP();
591 unsigned SlotSize = RegInfo->getSlotSize();
592 unsigned FramePtr = RegInfo->getFrameRegister(MF);
593 const unsigned MachineFramePtr =
594 STI.isTarget64BitILP32()
595 ? getX86SubSuperRegister(FramePtr, MVT::i64, false)
597 unsigned StackPtr = RegInfo->getStackRegister();
598 unsigned BasePtr = RegInfo->getBaseRegister();
601 // Add RETADDR move area to callee saved frame size.
602 int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta();
603 if (TailCallReturnAddrDelta && IsWinEH)
604 report_fatal_error("Can't handle guaranteed tail call under win64 yet");
606 if (TailCallReturnAddrDelta < 0)
607 X86FI->setCalleeSavedFrameSize(
608 X86FI->getCalleeSavedFrameSize() - TailCallReturnAddrDelta);
610 bool UseStackProbe = (STI.isOSWindows() && !STI.isTargetMachO());
612 // The default stack probe size is 4096 if the function has no stackprobesize
614 unsigned StackProbeSize = 4096;
615 if (Fn->hasFnAttribute("stack-probe-size"))
616 Fn->getFnAttribute("stack-probe-size")
618 .getAsInteger(0, StackProbeSize);
620 // If this is x86-64 and the Red Zone is not disabled, if we are a leaf
621 // function, and use up to 128 bytes of stack space, don't have a frame
622 // pointer, calls, or dynamic alloca then we do not need to adjust the
623 // stack pointer (we fit in the Red Zone). We also check that we don't
624 // push and pop from the stack.
625 if (Is64Bit && !Fn->hasFnAttribute(Attribute::NoRedZone) &&
626 !RegInfo->needsStackRealignment(MF) &&
627 !MFI->hasVarSizedObjects() && // No dynamic alloca.
628 !MFI->adjustsStack() && // No calls.
629 !IsWin64 && // Win64 has no Red Zone
630 !usesTheStack(MF) && // Don't push and pop.
631 !MF.shouldSplitStack()) { // Regular stack
632 uint64_t MinSize = X86FI->getCalleeSavedFrameSize();
633 if (HasFP) MinSize += SlotSize;
634 StackSize = std::max(MinSize, StackSize > 128 ? StackSize - 128 : 0);
635 MFI->setStackSize(StackSize);
638 // Insert stack pointer adjustment for later moving of return addr. Only
639 // applies to tail call optimized functions where the callee argument stack
640 // size is bigger than the callers.
641 if (TailCallReturnAddrDelta < 0) {
643 BuildMI(MBB, MBBI, DL,
644 TII.get(getSUBriOpcode(Uses64BitFramePtr, -TailCallReturnAddrDelta)),
647 .addImm(-TailCallReturnAddrDelta)
648 .setMIFlag(MachineInstr::FrameSetup);
649 MI->getOperand(3).setIsDead(); // The EFLAGS implicit def is dead.
652 // Mapping for machine moves:
654 // DST: VirtualFP AND
655 // SRC: VirtualFP => DW_CFA_def_cfa_offset
656 // ELSE => DW_CFA_def_cfa
658 // SRC: VirtualFP AND
659 // DST: Register => DW_CFA_def_cfa_register
662 // OFFSET < 0 => DW_CFA_offset_extended_sf
663 // REG < 64 => DW_CFA_offset + Reg
664 // ELSE => DW_CFA_offset_extended
666 uint64_t NumBytes = 0;
667 int stackGrowth = -SlotSize;
670 // Calculate required stack adjustment.
671 uint64_t FrameSize = StackSize - SlotSize;
672 // If required, include space for extra hidden slot for stashing base pointer.
673 if (X86FI->getRestoreBasePointer())
674 FrameSize += SlotSize;
676 NumBytes = FrameSize - X86FI->getCalleeSavedFrameSize();
678 // Callee-saved registers are pushed on stack before the stack is realigned.
679 if (RegInfo->needsStackRealignment(MF) && !IsWinEH)
680 NumBytes = RoundUpToAlignment(NumBytes, MaxAlign);
682 // Get the offset of the stack slot for the EBP register, which is
683 // guaranteed to be the last slot by processFunctionBeforeFrameFinalized.
684 // Update the frame offset adjustment.
685 MFI->setOffsetAdjustment(-NumBytes);
687 // Save EBP/RBP into the appropriate stack slot.
688 BuildMI(MBB, MBBI, DL, TII.get(Is64Bit ? X86::PUSH64r : X86::PUSH32r))
689 .addReg(MachineFramePtr, RegState::Kill)
690 .setMIFlag(MachineInstr::FrameSetup);
693 // Mark the place where EBP/RBP was saved.
694 // Define the current CFA rule to use the provided offset.
696 unsigned CFIIndex = MMI.addFrameInst(
697 MCCFIInstruction::createDefCfaOffset(nullptr, 2 * stackGrowth));
698 BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::CFI_INSTRUCTION))
699 .addCFIIndex(CFIIndex);
701 // Change the rule for the FramePtr to be an "offset" rule.
702 unsigned DwarfFramePtr = RegInfo->getDwarfRegNum(MachineFramePtr, true);
703 CFIIndex = MMI.addFrameInst(
704 MCCFIInstruction::createOffset(nullptr,
705 DwarfFramePtr, 2 * stackGrowth));
706 BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::CFI_INSTRUCTION))
707 .addCFIIndex(CFIIndex);
711 BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_PushReg))
713 .setMIFlag(MachineInstr::FrameSetup);
717 // Update EBP with the new base value.
718 BuildMI(MBB, MBBI, DL,
719 TII.get(Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr),
722 .setMIFlag(MachineInstr::FrameSetup);
726 // Mark effective beginning of when frame pointer becomes valid.
727 // Define the current CFA to use the EBP/RBP register.
728 unsigned DwarfFramePtr = RegInfo->getDwarfRegNum(MachineFramePtr, true);
729 unsigned CFIIndex = MMI.addFrameInst(
730 MCCFIInstruction::createDefCfaRegister(nullptr, DwarfFramePtr));
731 BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::CFI_INSTRUCTION))
732 .addCFIIndex(CFIIndex);
735 // Mark the FramePtr as live-in in every block.
736 for (MachineFunction::iterator I = MF.begin(), E = MF.end(); I != E; ++I)
737 I->addLiveIn(MachineFramePtr);
739 NumBytes = StackSize - X86FI->getCalleeSavedFrameSize();
742 // Skip the callee-saved push instructions.
743 bool PushedRegs = false;
744 int StackOffset = 2 * stackGrowth;
746 while (MBBI != MBB.end() &&
747 (MBBI->getOpcode() == X86::PUSH32r ||
748 MBBI->getOpcode() == X86::PUSH64r)) {
750 unsigned Reg = MBBI->getOperand(0).getReg();
753 if (!HasFP && NeedsDwarfCFI) {
754 // Mark callee-saved push instruction.
755 // Define the current CFA rule to use the provided offset.
757 unsigned CFIIndex = MMI.addFrameInst(
758 MCCFIInstruction::createDefCfaOffset(nullptr, StackOffset));
759 BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::CFI_INSTRUCTION))
760 .addCFIIndex(CFIIndex);
761 StackOffset += stackGrowth;
765 BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_PushReg)).addImm(Reg).setMIFlag(
766 MachineInstr::FrameSetup);
770 // Realign stack after we pushed callee-saved registers (so that we'll be
771 // able to calculate their offsets from the frame pointer).
772 // Don't do this for Win64, it needs to realign the stack after the prologue.
773 if (!IsWinEH && RegInfo->needsStackRealignment(MF)) {
774 assert(HasFP && "There should be a frame pointer if stack is realigned.");
775 uint64_t Val = -MaxAlign;
777 BuildMI(MBB, MBBI, DL, TII.get(getANDriOpcode(Uses64BitFramePtr, Val)),
781 .setMIFlag(MachineInstr::FrameSetup);
783 // The EFLAGS implicit def is dead.
784 MI->getOperand(3).setIsDead();
787 // If there is an SUB32ri of ESP immediately before this instruction, merge
788 // the two. This can be the case when tail call elimination is enabled and
789 // the callee has more arguments then the caller.
790 NumBytes -= mergeSPUpdates(MBB, MBBI, StackPtr, true);
792 // Adjust stack pointer: ESP -= numbytes.
794 // Windows and cygwin/mingw require a prologue helper routine when allocating
795 // more than 4K bytes on the stack. Windows uses __chkstk and cygwin/mingw
796 // uses __alloca. __alloca and the 32-bit version of __chkstk will probe the
797 // stack and adjust the stack pointer in one go. The 64-bit version of
798 // __chkstk is only responsible for probing the stack. The 64-bit prologue is
799 // responsible for adjusting the stack pointer. Touching the stack at 4K
800 // increments is necessary to ensure that the guard pages used by the OS
801 // virtual memory manager are allocated in correct sequence.
802 uint64_t AlignedNumBytes = NumBytes;
803 if (IsWinEH && RegInfo->needsStackRealignment(MF))
804 AlignedNumBytes = RoundUpToAlignment(AlignedNumBytes, MaxAlign);
805 if (AlignedNumBytes >= StackProbeSize && UseStackProbe) {
806 // Check whether EAX is livein for this function.
807 bool isEAXAlive = isEAXLiveIn(MF);
810 // Sanity check that EAX is not livein for this function.
811 // It should not be, so throw an assert.
812 assert(!Is64Bit && "EAX is livein in x64 case!");
815 BuildMI(MBB, MBBI, DL, TII.get(X86::PUSH32r))
816 .addReg(X86::EAX, RegState::Kill)
817 .setMIFlag(MachineInstr::FrameSetup);
821 // Handle the 64-bit Windows ABI case where we need to call __chkstk.
822 // Function prologue is responsible for adjusting the stack pointer.
823 if (isUInt<32>(NumBytes)) {
824 BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX)
826 .setMIFlag(MachineInstr::FrameSetup);
827 } else if (isInt<32>(NumBytes)) {
828 BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64ri32), X86::RAX)
830 .setMIFlag(MachineInstr::FrameSetup);
832 BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64ri), X86::RAX)
834 .setMIFlag(MachineInstr::FrameSetup);
837 // Allocate NumBytes-4 bytes on stack in case of isEAXAlive.
838 // We'll also use 4 already allocated bytes for EAX.
839 BuildMI(MBB, MBBI, DL, TII.get(X86::MOV32ri), X86::EAX)
840 .addImm(isEAXAlive ? NumBytes - 4 : NumBytes)
841 .setMIFlag(MachineInstr::FrameSetup);
844 // Save a pointer to the MI where we set AX.
845 MachineBasicBlock::iterator SetRAX = MBBI;
848 // Call __chkstk, __chkstk_ms, or __alloca.
849 emitStackProbeCall(MF, MBB, MBBI, DL);
851 // Apply the frame setup flag to all inserted instrs.
852 for (; SetRAX != MBBI; ++SetRAX)
853 SetRAX->setFlag(MachineInstr::FrameSetup);
857 MachineInstr *MI = addRegOffset(BuildMI(MF, DL, TII.get(X86::MOV32rm),
859 StackPtr, false, NumBytes - 4);
860 MI->setFlag(MachineInstr::FrameSetup);
861 MBB.insert(MBBI, MI);
863 } else if (NumBytes) {
864 emitSPUpdate(MBB, MBBI, StackPtr, -(int64_t)NumBytes, Is64Bit, Uses64BitFramePtr,
865 UseLEA, TII, *RegInfo);
868 if (NeedsWinEH && NumBytes)
869 BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_StackAlloc))
871 .setMIFlag(MachineInstr::FrameSetup);
873 int SEHFrameOffset = 0;
874 if (IsWinEH && HasFP) {
875 SEHFrameOffset = calculateSetFPREG(NumBytes);
877 addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(X86::LEA64r), FramePtr),
878 StackPtr, false, SEHFrameOffset);
880 BuildMI(MBB, MBBI, DL, TII.get(X86::MOV64rr), FramePtr).addReg(StackPtr);
883 BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_SetFrame))
885 .addImm(SEHFrameOffset)
886 .setMIFlag(MachineInstr::FrameSetup);
889 while (MBBI != MBB.end() && MBBI->getFlag(MachineInstr::FrameSetup)) {
890 const MachineInstr *FrameInstr = &*MBBI;
895 if (unsigned Reg = TII.isStoreToStackSlot(FrameInstr, FI)) {
896 if (X86::FR64RegClass.contains(Reg)) {
897 int Offset = getFrameIndexOffset(MF, FI);
898 Offset += SEHFrameOffset;
900 BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_SaveXMM))
903 .setMIFlag(MachineInstr::FrameSetup);
910 BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_EndPrologue))
911 .setMIFlag(MachineInstr::FrameSetup);
913 // Realign stack after we spilled callee-saved registers (so that we'll be
914 // able to calculate their offsets from the frame pointer).
915 // Win64 requires aligning the stack after the prologue.
916 if (IsWinEH && RegInfo->needsStackRealignment(MF)) {
917 assert(HasFP && "There should be a frame pointer if stack is realigned.");
918 uint64_t Val = -MaxAlign;
920 BuildMI(MBB, MBBI, DL, TII.get(getANDriOpcode(Uses64BitFramePtr, Val)),
924 .setMIFlag(MachineInstr::FrameSetup);
926 // The EFLAGS implicit def is dead.
927 MI->getOperand(3).setIsDead();
930 // If we need a base pointer, set it up here. It's whatever the value
931 // of the stack pointer is at this point. Any variable size objects
932 // will be allocated after this, so we can still use the base pointer
933 // to reference locals.
934 if (RegInfo->hasBasePointer(MF)) {
935 // Update the base pointer with the current stack pointer.
936 unsigned Opc = Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr;
937 BuildMI(MBB, MBBI, DL, TII.get(Opc), BasePtr)
939 .setMIFlag(MachineInstr::FrameSetup);
940 if (X86FI->getRestoreBasePointer()) {
941 // Stash value of base pointer. Saving RSP instead of EBP shortens dependence chain.
942 unsigned Opm = Uses64BitFramePtr ? X86::MOV64mr : X86::MOV32mr;
943 addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opm)),
944 FramePtr, true, X86FI->getRestoreBasePointerOffset())
946 .setMIFlag(MachineInstr::FrameSetup);
950 if (((!HasFP && NumBytes) || PushedRegs) && NeedsDwarfCFI) {
951 // Mark end of stack pointer adjustment.
952 if (!HasFP && NumBytes) {
953 // Define the current CFA rule to use the provided offset.
955 unsigned CFIIndex = MMI.addFrameInst(
956 MCCFIInstruction::createDefCfaOffset(nullptr,
957 -StackSize + stackGrowth));
959 BuildMI(MBB, MBBI, DL, TII.get(TargetOpcode::CFI_INSTRUCTION))
960 .addCFIIndex(CFIIndex);
963 // Emit DWARF info specifying the offsets of the callee-saved registers.
965 emitCalleeSavedFrameMoves(MBB, MBBI, DL);
969 void X86FrameLowering::emitEpilogue(MachineFunction &MF,
970 MachineBasicBlock &MBB) const {
971 const MachineFrameInfo *MFI = MF.getFrameInfo();
972 X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
973 const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
974 const X86RegisterInfo *RegInfo = STI.getRegisterInfo();
975 const TargetInstrInfo &TII = *STI.getInstrInfo();
976 MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
977 assert(MBBI != MBB.end() && "Returning block has no instructions");
978 unsigned RetOpcode = MBBI->getOpcode();
979 DebugLoc DL = MBBI->getDebugLoc();
980 bool Is64Bit = STI.is64Bit();
981 // standard x86_64 and NaCl use 64-bit frame/stack pointers, x32 - 32-bit.
982 const bool Uses64BitFramePtr = STI.isTarget64BitLP64() || STI.isTargetNaCl64();
983 bool HasFP = hasFP(MF);
984 const bool Is64BitILP32 = STI.isTarget64BitILP32();
985 unsigned SlotSize = RegInfo->getSlotSize();
986 unsigned FramePtr = RegInfo->getFrameRegister(MF);
987 unsigned MachineFramePtr =
988 Is64BitILP32 ? getX86SubSuperRegister(FramePtr, MVT::i64, false)
990 unsigned StackPtr = RegInfo->getStackRegister();
992 bool IsWinEH = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
993 bool NeedsWinEH = IsWinEH && MF.getFunction()->needsUnwindTableEntry();
994 bool UseLEAForSP = false;
996 // We can't use LEA instructions for adjusting the stack pointer if this is a
997 // leaf function in the Win64 ABI. Only ADD instructions may be used to
998 // deallocate the stack.
999 if (STI.useLeaForSP()) {
1001 // We *aren't* using the Win64 ABI which means we are free to use LEA.
1004 // We *have* a frame pointer which means we are permitted to use LEA.
1009 switch (RetOpcode) {
1011 llvm_unreachable("Can only insert epilogue into returning blocks");
1016 case X86::TCRETURNdi:
1017 case X86::TCRETURNri:
1018 case X86::TCRETURNmi:
1019 case X86::TCRETURNdi64:
1020 case X86::TCRETURNri64:
1021 case X86::TCRETURNmi64:
1022 case X86::EH_RETURN:
1023 case X86::EH_RETURN64:
1024 break; // These are ok
1027 // Get the number of bytes to allocate from the FrameInfo.
1028 uint64_t StackSize = MFI->getStackSize();
1029 uint64_t MaxAlign = calculateMaxStackAlign(MF);
1030 unsigned CSSize = X86FI->getCalleeSavedFrameSize();
1031 uint64_t NumBytes = 0;
1034 // Calculate required stack adjustment.
1035 uint64_t FrameSize = StackSize - SlotSize;
1036 NumBytes = FrameSize - CSSize;
1038 // Callee-saved registers were pushed on stack before the stack was
1040 if (RegInfo->needsStackRealignment(MF) && !IsWinEH)
1041 NumBytes = RoundUpToAlignment(FrameSize, MaxAlign);
1044 BuildMI(MBB, MBBI, DL,
1045 TII.get(Is64Bit ? X86::POP64r : X86::POP32r), MachineFramePtr);
1047 NumBytes = StackSize - CSSize;
1049 uint64_t SEHStackAllocAmt = NumBytes;
1051 // Skip the callee-saved pop instructions.
1052 while (MBBI != MBB.begin()) {
1053 MachineBasicBlock::iterator PI = std::prev(MBBI);
1054 unsigned Opc = PI->getOpcode();
1056 if (Opc != X86::POP32r && Opc != X86::POP64r && Opc != X86::DBG_VALUE &&
1057 !PI->isTerminator())
1062 MachineBasicBlock::iterator FirstCSPop = MBBI;
1064 DL = MBBI->getDebugLoc();
1066 // If there is an ADD32ri or SUB32ri of ESP immediately before this
1067 // instruction, merge the two instructions.
1068 if (NumBytes || MFI->hasVarSizedObjects())
1069 mergeSPUpdatesUp(MBB, MBBI, StackPtr, &NumBytes);
1071 // If dynamic alloca is used, then reset esp to point to the last callee-saved
1072 // slot before popping them off! Same applies for the case, when stack was
1074 if (RegInfo->needsStackRealignment(MF) || MFI->hasVarSizedObjects()) {
1075 if (RegInfo->needsStackRealignment(MF))
1077 unsigned SEHFrameOffset = calculateSetFPREG(SEHStackAllocAmt);
1078 uint64_t LEAAmount = IsWinEH ? SEHStackAllocAmt - SEHFrameOffset : -CSSize;
1080 // There are only two legal forms of epilogue:
1081 // - add SEHAllocationSize, %rsp
1082 // - lea SEHAllocationSize(%FramePtr), %rsp
1084 // 'mov %FramePtr, %rsp' will not be recognized as an epilogue sequence.
1085 // However, we may use this sequence if we have a frame pointer because the
1086 // effects of the prologue can safely be undone.
1087 if (LEAAmount != 0) {
1088 unsigned Opc = getLEArOpcode(Uses64BitFramePtr);
1089 addRegOffset(BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr),
1090 FramePtr, false, LEAAmount);
1093 unsigned Opc = (Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr);
1094 BuildMI(MBB, MBBI, DL, TII.get(Opc), StackPtr)
1098 } else if (NumBytes) {
1099 // Adjust stack pointer back: ESP += numbytes.
1100 emitSPUpdate(MBB, MBBI, StackPtr, NumBytes, Is64Bit, Uses64BitFramePtr,
1101 UseLEAForSP, TII, *RegInfo);
1105 // Windows unwinder will not invoke function's exception handler if IP is
1106 // either in prologue or in epilogue. This behavior causes a problem when a
1107 // call immediately precedes an epilogue, because the return address points
1108 // into the epilogue. To cope with that, we insert an epilogue marker here,
1109 // then replace it with a 'nop' if it ends up immediately after a CALL in the
1110 // final emitted code.
1112 BuildMI(MBB, MBBI, DL, TII.get(X86::SEH_Epilogue));
1114 // We're returning from function via eh_return.
1115 if (RetOpcode == X86::EH_RETURN || RetOpcode == X86::EH_RETURN64) {
1116 MBBI = MBB.getLastNonDebugInstr();
1117 MachineOperand &DestAddr = MBBI->getOperand(0);
1118 assert(DestAddr.isReg() && "Offset should be in register!");
1119 BuildMI(MBB, MBBI, DL,
1120 TII.get(Uses64BitFramePtr ? X86::MOV64rr : X86::MOV32rr),
1121 StackPtr).addReg(DestAddr.getReg());
1122 } else if (RetOpcode == X86::TCRETURNri || RetOpcode == X86::TCRETURNdi ||
1123 RetOpcode == X86::TCRETURNmi ||
1124 RetOpcode == X86::TCRETURNri64 || RetOpcode == X86::TCRETURNdi64 ||
1125 RetOpcode == X86::TCRETURNmi64) {
1126 bool isMem = RetOpcode == X86::TCRETURNmi || RetOpcode == X86::TCRETURNmi64;
1127 // Tail call return: adjust the stack pointer and jump to callee.
1128 MBBI = MBB.getLastNonDebugInstr();
1129 MachineOperand &JumpTarget = MBBI->getOperand(0);
1130 MachineOperand &StackAdjust = MBBI->getOperand(isMem ? 5 : 1);
1131 assert(StackAdjust.isImm() && "Expecting immediate value.");
1133 // Adjust stack pointer.
1134 int StackAdj = StackAdjust.getImm();
1135 int MaxTCDelta = X86FI->getTCReturnAddrDelta();
1137 assert(MaxTCDelta <= 0 && "MaxTCDelta should never be positive");
1139 // Incoporate the retaddr area.
1140 Offset = StackAdj-MaxTCDelta;
1141 assert(Offset >= 0 && "Offset should never be negative");
1144 // Check for possible merge with preceding ADD instruction.
1145 Offset += mergeSPUpdates(MBB, MBBI, StackPtr, true);
1146 emitSPUpdate(MBB, MBBI, StackPtr, Offset, Is64Bit, Uses64BitFramePtr,
1147 UseLEAForSP, TII, *RegInfo);
1150 // Jump to label or value in register.
1151 bool IsWin64 = STI.isTargetWin64();
1152 if (RetOpcode == X86::TCRETURNdi || RetOpcode == X86::TCRETURNdi64) {
1153 unsigned Op = (RetOpcode == X86::TCRETURNdi)
1155 : (IsWin64 ? X86::TAILJMPd64_REX : X86::TAILJMPd64);
1156 MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII.get(Op));
1157 if (JumpTarget.isGlobal())
1158 MIB.addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset(),
1159 JumpTarget.getTargetFlags());
1161 assert(JumpTarget.isSymbol());
1162 MIB.addExternalSymbol(JumpTarget.getSymbolName(),
1163 JumpTarget.getTargetFlags());
1165 } else if (RetOpcode == X86::TCRETURNmi || RetOpcode == X86::TCRETURNmi64) {
1166 unsigned Op = (RetOpcode == X86::TCRETURNmi)
1168 : (IsWin64 ? X86::TAILJMPm64_REX : X86::TAILJMPm64);
1169 MachineInstrBuilder MIB = BuildMI(MBB, MBBI, DL, TII.get(Op));
1170 for (unsigned i = 0; i != 5; ++i)
1171 MIB.addOperand(MBBI->getOperand(i));
1172 } else if (RetOpcode == X86::TCRETURNri64) {
1173 BuildMI(MBB, MBBI, DL,
1174 TII.get(IsWin64 ? X86::TAILJMPr64_REX : X86::TAILJMPr64))
1175 .addReg(JumpTarget.getReg(), RegState::Kill);
1177 BuildMI(MBB, MBBI, DL, TII.get(X86::TAILJMPr)).
1178 addReg(JumpTarget.getReg(), RegState::Kill);
1181 MachineInstr *NewMI = std::prev(MBBI);
1182 NewMI->copyImplicitOps(MF, MBBI);
1184 // Delete the pseudo instruction TCRETURN.
1186 } else if ((RetOpcode == X86::RETQ || RetOpcode == X86::RETL ||
1187 RetOpcode == X86::RETIQ || RetOpcode == X86::RETIL) &&
1188 (X86FI->getTCReturnAddrDelta() < 0)) {
1189 // Add the return addr area delta back since we are not tail calling.
1190 int delta = -1*X86FI->getTCReturnAddrDelta();
1191 MBBI = MBB.getLastNonDebugInstr();
1193 // Check for possible merge with preceding ADD instruction.
1194 delta += mergeSPUpdates(MBB, MBBI, StackPtr, true);
1195 emitSPUpdate(MBB, MBBI, StackPtr, delta, Is64Bit, Uses64BitFramePtr,
1196 UseLEAForSP, TII, *RegInfo);
1200 int X86FrameLowering::getFrameIndexOffset(const MachineFunction &MF,
1202 const X86RegisterInfo *RegInfo =
1203 MF.getSubtarget<X86Subtarget>().getRegisterInfo();
1204 const MachineFrameInfo *MFI = MF.getFrameInfo();
1205 // Offset will hold the offset from the stack pointer at function entry to the
1207 // We need to factor in additional offsets applied during the prologue to the
1208 // frame, base, and stack pointer depending on which is used.
1209 int Offset = MFI->getObjectOffset(FI) - getOffsetOfLocalArea();
1210 const X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
1211 unsigned CSSize = X86FI->getCalleeSavedFrameSize();
1212 uint64_t StackSize = MFI->getStackSize();
1213 unsigned SlotSize = RegInfo->getSlotSize();
1214 bool HasFP = hasFP(MF);
1215 bool IsWinEH = MF.getTarget().getMCAsmInfo()->usesWindowsCFI();
1216 int64_t FPDelta = 0;
1219 assert(!MFI->hasCalls() || (StackSize % 16) == 8);
1221 // Calculate required stack adjustment.
1222 uint64_t FrameSize = StackSize - SlotSize;
1223 // If required, include space for extra hidden slot for stashing base pointer.
1224 if (X86FI->getRestoreBasePointer())
1225 FrameSize += SlotSize;
1226 uint64_t NumBytes = FrameSize - CSSize;
1228 uint64_t SEHFrameOffset = calculateSetFPREG(NumBytes);
1229 if (FI && FI == X86FI->getFAIndex())
1230 return -SEHFrameOffset;
1232 // FPDelta is the offset from the "traditional" FP location of the old base
1233 // pointer followed by return address and the location required by the
1234 // restricted Win64 prologue.
1235 // Add FPDelta to all offsets below that go through the frame pointer.
1236 FPDelta = FrameSize - SEHFrameOffset;
1237 assert((!MFI->hasCalls() || (FPDelta % 16) == 0) &&
1238 "FPDelta isn't aligned per the Win64 ABI!");
1242 if (RegInfo->hasBasePointer(MF)) {
1243 assert(HasFP && "VLAs and dynamic stack realign, but no FP?!");
1245 // Skip the saved EBP.
1246 return Offset + SlotSize + FPDelta;
1248 assert((-(Offset + StackSize)) % MFI->getObjectAlignment(FI) == 0);
1249 return Offset + StackSize;
1251 } else if (RegInfo->needsStackRealignment(MF)) {
1253 // Skip the saved EBP.
1254 return Offset + SlotSize + FPDelta;
1256 assert((-(Offset + StackSize)) % MFI->getObjectAlignment(FI) == 0);
1257 return Offset + StackSize;
1259 // FIXME: Support tail calls
1262 return Offset + StackSize;
1264 // Skip the saved EBP.
1267 // Skip the RETADDR move area
1268 int TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta();
1269 if (TailCallReturnAddrDelta < 0)
1270 Offset -= TailCallReturnAddrDelta;
1273 return Offset + FPDelta;
1276 int X86FrameLowering::getFrameIndexReference(const MachineFunction &MF, int FI,
1277 unsigned &FrameReg) const {
1278 const X86RegisterInfo *RegInfo =
1279 MF.getSubtarget<X86Subtarget>().getRegisterInfo();
1280 // We can't calculate offset from frame pointer if the stack is realigned,
1281 // so enforce usage of stack/base pointer. The base pointer is used when we
1282 // have dynamic allocas in addition to dynamic realignment.
1283 if (RegInfo->hasBasePointer(MF))
1284 FrameReg = RegInfo->getBaseRegister();
1285 else if (RegInfo->needsStackRealignment(MF))
1286 FrameReg = RegInfo->getStackRegister();
1288 FrameReg = RegInfo->getFrameRegister(MF);
1289 return getFrameIndexOffset(MF, FI);
1292 // Simplified from getFrameIndexOffset keeping only StackPointer cases
1293 int X86FrameLowering::getFrameIndexOffsetFromSP(const MachineFunction &MF, int FI) const {
1294 const MachineFrameInfo *MFI = MF.getFrameInfo();
1295 // Does not include any dynamic realign.
1296 const uint64_t StackSize = MFI->getStackSize();
1299 const X86RegisterInfo *RegInfo =
1300 MF.getSubtarget<X86Subtarget>().getRegisterInfo();
1301 // Note: LLVM arranges the stack as:
1302 // Args > Saved RetPC (<--FP) > CSRs > dynamic alignment (<--BP)
1303 // > "Stack Slots" (<--SP)
1304 // We can always address StackSlots from RSP. We can usually (unless
1305 // needsStackRealignment) address CSRs from RSP, but sometimes need to
1306 // address them from RBP. FixedObjects can be placed anywhere in the stack
1307 // frame depending on their specific requirements (i.e. we can actually
1308 // refer to arguments to the function which are stored in the *callers*
1309 // frame). As a result, THE RESULT OF THIS CALL IS MEANINGLESS FOR CSRs
1310 // AND FixedObjects IFF needsStackRealignment or hasVarSizedObject.
1312 assert(!RegInfo->hasBasePointer(MF) && "we don't handle this case");
1314 // We don't handle tail calls, and shouldn't be seeing them
1316 int TailCallReturnAddrDelta =
1317 MF.getInfo<X86MachineFunctionInfo>()->getTCReturnAddrDelta();
1318 assert(!(TailCallReturnAddrDelta < 0) && "we don't handle this case!");
1322 // This is how the math works out:
1324 // %rsp grows (i.e. gets lower) left to right. Each box below is
1325 // one word (eight bytes). Obj0 is the stack slot we're trying to
1328 // ----------------------------------
1329 // | BP | Obj0 | Obj1 | ... | ObjN |
1330 // ----------------------------------
1334 // A is the incoming stack pointer.
1335 // (B - A) is the local area offset (-8 for x86-64) [1]
1336 // (C - A) is the Offset returned by MFI->getObjectOffset for Obj0 [2]
1338 // |(E - B)| is the StackSize (absolute value, positive). For a
1339 // stack that grown down, this works out to be (B - E). [3]
1341 // E is also the value of %rsp after stack has been set up, and we
1342 // want (C - E) -- the value we can add to %rsp to get to Obj0. Now
1343 // (C - E) == (C - A) - (B - A) + (B - E)
1344 // { Using [1], [2] and [3] above }
1345 // == getObjectOffset - LocalAreaOffset + StackSize
1348 // Get the Offset from the StackPointer
1349 int Offset = MFI->getObjectOffset(FI) - getOffsetOfLocalArea();
1351 return Offset + StackSize;
1353 // Simplified from getFrameIndexReference keeping only StackPointer cases
1354 int X86FrameLowering::getFrameIndexReferenceFromSP(const MachineFunction &MF,
1356 unsigned &FrameReg) const {
1357 const X86RegisterInfo *RegInfo =
1358 MF.getSubtarget<X86Subtarget>().getRegisterInfo();
1359 assert(!RegInfo->hasBasePointer(MF) && "we don't handle this case");
1361 FrameReg = RegInfo->getStackRegister();
1362 return getFrameIndexOffsetFromSP(MF, FI);
1365 bool X86FrameLowering::assignCalleeSavedSpillSlots(
1366 MachineFunction &MF, const TargetRegisterInfo *TRI,
1367 std::vector<CalleeSavedInfo> &CSI) const {
1368 MachineFrameInfo *MFI = MF.getFrameInfo();
1369 const X86RegisterInfo *RegInfo =
1370 MF.getSubtarget<X86Subtarget>().getRegisterInfo();
1371 unsigned SlotSize = RegInfo->getSlotSize();
1372 X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
1374 unsigned CalleeSavedFrameSize = 0;
1375 int SpillSlotOffset = getOffsetOfLocalArea() + X86FI->getTCReturnAddrDelta();
1378 // emitPrologue always spills frame register the first thing.
1379 SpillSlotOffset -= SlotSize;
1380 MFI->CreateFixedSpillStackObject(SlotSize, SpillSlotOffset);
1382 // Since emitPrologue and emitEpilogue will handle spilling and restoring of
1383 // the frame register, we can delete it from CSI list and not have to worry
1384 // about avoiding it later.
1385 unsigned FPReg = RegInfo->getFrameRegister(MF);
1386 for (unsigned i = 0; i < CSI.size(); ++i) {
1387 if (TRI->regsOverlap(CSI[i].getReg(),FPReg)) {
1388 CSI.erase(CSI.begin() + i);
1394 // Assign slots for GPRs. It increases frame size.
1395 for (unsigned i = CSI.size(); i != 0; --i) {
1396 unsigned Reg = CSI[i - 1].getReg();
1398 if (!X86::GR64RegClass.contains(Reg) && !X86::GR32RegClass.contains(Reg))
1401 SpillSlotOffset -= SlotSize;
1402 CalleeSavedFrameSize += SlotSize;
1404 int SlotIndex = MFI->CreateFixedSpillStackObject(SlotSize, SpillSlotOffset);
1405 CSI[i - 1].setFrameIdx(SlotIndex);
1408 X86FI->setCalleeSavedFrameSize(CalleeSavedFrameSize);
1410 // Assign slots for XMMs.
1411 for (unsigned i = CSI.size(); i != 0; --i) {
1412 unsigned Reg = CSI[i - 1].getReg();
1413 if (X86::GR64RegClass.contains(Reg) || X86::GR32RegClass.contains(Reg))
1416 const TargetRegisterClass *RC = RegInfo->getMinimalPhysRegClass(Reg);
1418 SpillSlotOffset -= std::abs(SpillSlotOffset) % RC->getAlignment();
1420 SpillSlotOffset -= RC->getSize();
1422 MFI->CreateFixedSpillStackObject(RC->getSize(), SpillSlotOffset);
1423 CSI[i - 1].setFrameIdx(SlotIndex);
1424 MFI->ensureMaxAlignment(RC->getAlignment());
1430 bool X86FrameLowering::spillCalleeSavedRegisters(
1431 MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
1432 const std::vector<CalleeSavedInfo> &CSI,
1433 const TargetRegisterInfo *TRI) const {
1434 DebugLoc DL = MBB.findDebugLoc(MI);
1436 MachineFunction &MF = *MBB.getParent();
1437 const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
1438 const TargetInstrInfo &TII = *STI.getInstrInfo();
1440 // Push GPRs. It increases frame size.
1441 unsigned Opc = STI.is64Bit() ? X86::PUSH64r : X86::PUSH32r;
1442 for (unsigned i = CSI.size(); i != 0; --i) {
1443 unsigned Reg = CSI[i - 1].getReg();
1445 if (!X86::GR64RegClass.contains(Reg) && !X86::GR32RegClass.contains(Reg))
1447 // Add the callee-saved register as live-in. It's killed at the spill.
1450 BuildMI(MBB, MI, DL, TII.get(Opc)).addReg(Reg, RegState::Kill)
1451 .setMIFlag(MachineInstr::FrameSetup);
1454 // Make XMM regs spilled. X86 does not have ability of push/pop XMM.
1455 // It can be done by spilling XMMs to stack frame.
1456 for (unsigned i = CSI.size(); i != 0; --i) {
1457 unsigned Reg = CSI[i-1].getReg();
1458 if (X86::GR64RegClass.contains(Reg) || X86::GR32RegClass.contains(Reg))
1460 // Add the callee-saved register as live-in. It's killed at the spill.
1462 const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
1464 TII.storeRegToStackSlot(MBB, MI, Reg, true, CSI[i - 1].getFrameIdx(), RC,
1467 MI->setFlag(MachineInstr::FrameSetup);
1474 bool X86FrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
1475 MachineBasicBlock::iterator MI,
1476 const std::vector<CalleeSavedInfo> &CSI,
1477 const TargetRegisterInfo *TRI) const {
1481 DebugLoc DL = MBB.findDebugLoc(MI);
1483 MachineFunction &MF = *MBB.getParent();
1484 const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
1485 const TargetInstrInfo &TII = *STI.getInstrInfo();
1487 // Reload XMMs from stack frame.
1488 for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
1489 unsigned Reg = CSI[i].getReg();
1490 if (X86::GR64RegClass.contains(Reg) ||
1491 X86::GR32RegClass.contains(Reg))
1494 const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
1495 TII.loadRegFromStackSlot(MBB, MI, Reg, CSI[i].getFrameIdx(), RC, TRI);
1499 unsigned Opc = STI.is64Bit() ? X86::POP64r : X86::POP32r;
1500 for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
1501 unsigned Reg = CSI[i].getReg();
1502 if (!X86::GR64RegClass.contains(Reg) &&
1503 !X86::GR32RegClass.contains(Reg))
1506 BuildMI(MBB, MI, DL, TII.get(Opc), Reg);
1512 X86FrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
1513 RegScavenger *RS) const {
1514 MachineFrameInfo *MFI = MF.getFrameInfo();
1515 const X86RegisterInfo *RegInfo =
1516 MF.getSubtarget<X86Subtarget>().getRegisterInfo();
1517 unsigned SlotSize = RegInfo->getSlotSize();
1519 X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
1520 int64_t TailCallReturnAddrDelta = X86FI->getTCReturnAddrDelta();
1522 if (TailCallReturnAddrDelta < 0) {
1523 // create RETURNADDR area
1532 MFI->CreateFixedObject(-TailCallReturnAddrDelta,
1533 TailCallReturnAddrDelta - SlotSize, true);
1536 // Spill the BasePtr if it's used.
1537 if (RegInfo->hasBasePointer(MF))
1538 MF.getRegInfo().setPhysRegUsed(RegInfo->getBaseRegister());
1542 HasNestArgument(const MachineFunction *MF) {
1543 const Function *F = MF->getFunction();
1544 for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
1546 if (I->hasNestAttr())
1552 /// GetScratchRegister - Get a temp register for performing work in the
1553 /// segmented stack and the Erlang/HiPE stack prologue. Depending on platform
1554 /// and the properties of the function either one or two registers will be
1555 /// needed. Set primary to true for the first register, false for the second.
1557 GetScratchRegister(bool Is64Bit, bool IsLP64, const MachineFunction &MF, bool Primary) {
1558 CallingConv::ID CallingConvention = MF.getFunction()->getCallingConv();
1561 if (CallingConvention == CallingConv::HiPE) {
1563 return Primary ? X86::R14 : X86::R13;
1565 return Primary ? X86::EBX : X86::EDI;
1570 return Primary ? X86::R11 : X86::R12;
1572 return Primary ? X86::R11D : X86::R12D;
1575 bool IsNested = HasNestArgument(&MF);
1577 if (CallingConvention == CallingConv::X86_FastCall ||
1578 CallingConvention == CallingConv::Fast) {
1580 report_fatal_error("Segmented stacks does not support fastcall with "
1581 "nested function.");
1582 return Primary ? X86::EAX : X86::ECX;
1585 return Primary ? X86::EDX : X86::EAX;
1586 return Primary ? X86::ECX : X86::EAX;
1589 // The stack limit in the TCB is set to this many bytes above the actual stack
1591 static const uint64_t kSplitStackAvailable = 256;
1594 X86FrameLowering::adjustForSegmentedStacks(MachineFunction &MF) const {
1595 MachineBasicBlock &prologueMBB = MF.front();
1596 MachineFrameInfo *MFI = MF.getFrameInfo();
1597 const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
1598 const TargetInstrInfo &TII = *STI.getInstrInfo();
1600 bool Is64Bit = STI.is64Bit();
1601 const bool IsLP64 = STI.isTarget64BitLP64();
1602 unsigned TlsReg, TlsOffset;
1605 unsigned ScratchReg = GetScratchRegister(Is64Bit, IsLP64, MF, true);
1606 assert(!MF.getRegInfo().isLiveIn(ScratchReg) &&
1607 "Scratch register is live-in");
1609 if (MF.getFunction()->isVarArg())
1610 report_fatal_error("Segmented stacks do not support vararg functions.");
1611 if (!STI.isTargetLinux() && !STI.isTargetDarwin() && !STI.isTargetWin32() &&
1612 !STI.isTargetWin64() && !STI.isTargetFreeBSD() &&
1613 !STI.isTargetDragonFly())
1614 report_fatal_error("Segmented stacks not supported on this platform.");
1616 // Eventually StackSize will be calculated by a link-time pass; which will
1617 // also decide whether checking code needs to be injected into this particular
1619 StackSize = MFI->getStackSize();
1621 // Do not generate a prologue for functions with a stack of size zero
1625 MachineBasicBlock *allocMBB = MF.CreateMachineBasicBlock();
1626 MachineBasicBlock *checkMBB = MF.CreateMachineBasicBlock();
1627 X86MachineFunctionInfo *X86FI = MF.getInfo<X86MachineFunctionInfo>();
1628 bool IsNested = false;
1630 // We need to know if the function has a nest argument only in 64 bit mode.
1632 IsNested = HasNestArgument(&MF);
1634 // The MOV R10, RAX needs to be in a different block, since the RET we emit in
1635 // allocMBB needs to be last (terminating) instruction.
1637 for (MachineBasicBlock::livein_iterator i = prologueMBB.livein_begin(),
1638 e = prologueMBB.livein_end(); i != e; i++) {
1639 allocMBB->addLiveIn(*i);
1640 checkMBB->addLiveIn(*i);
1644 allocMBB->addLiveIn(IsLP64 ? X86::R10 : X86::R10D);
1646 MF.push_front(allocMBB);
1647 MF.push_front(checkMBB);
1649 // When the frame size is less than 256 we just compare the stack
1650 // boundary directly to the value of the stack pointer, per gcc.
1651 bool CompareStackPointer = StackSize < kSplitStackAvailable;
1653 // Read the limit off the current stacklet off the stack_guard location.
1655 if (STI.isTargetLinux()) {
1657 TlsOffset = IsLP64 ? 0x70 : 0x40;
1658 } else if (STI.isTargetDarwin()) {
1660 TlsOffset = 0x60 + 90*8; // See pthread_machdep.h. Steal TLS slot 90.
1661 } else if (STI.isTargetWin64()) {
1663 TlsOffset = 0x28; // pvArbitrary, reserved for application use
1664 } else if (STI.isTargetFreeBSD()) {
1667 } else if (STI.isTargetDragonFly()) {
1669 TlsOffset = 0x20; // use tls_tcb.tcb_segstack
1671 report_fatal_error("Segmented stacks not supported on this platform.");
1674 if (CompareStackPointer)
1675 ScratchReg = IsLP64 ? X86::RSP : X86::ESP;
1677 BuildMI(checkMBB, DL, TII.get(IsLP64 ? X86::LEA64r : X86::LEA64_32r), ScratchReg).addReg(X86::RSP)
1678 .addImm(1).addReg(0).addImm(-StackSize).addReg(0);
1680 BuildMI(checkMBB, DL, TII.get(IsLP64 ? X86::CMP64rm : X86::CMP32rm)).addReg(ScratchReg)
1681 .addReg(0).addImm(1).addReg(0).addImm(TlsOffset).addReg(TlsReg);
1683 if (STI.isTargetLinux()) {
1686 } else if (STI.isTargetDarwin()) {
1688 TlsOffset = 0x48 + 90*4;
1689 } else if (STI.isTargetWin32()) {
1691 TlsOffset = 0x14; // pvArbitrary, reserved for application use
1692 } else if (STI.isTargetDragonFly()) {
1694 TlsOffset = 0x10; // use tls_tcb.tcb_segstack
1695 } else if (STI.isTargetFreeBSD()) {
1696 report_fatal_error("Segmented stacks not supported on FreeBSD i386.");
1698 report_fatal_error("Segmented stacks not supported on this platform.");
1701 if (CompareStackPointer)
1702 ScratchReg = X86::ESP;
1704 BuildMI(checkMBB, DL, TII.get(X86::LEA32r), ScratchReg).addReg(X86::ESP)
1705 .addImm(1).addReg(0).addImm(-StackSize).addReg(0);
1707 if (STI.isTargetLinux() || STI.isTargetWin32() || STI.isTargetWin64() ||
1708 STI.isTargetDragonFly()) {
1709 BuildMI(checkMBB, DL, TII.get(X86::CMP32rm)).addReg(ScratchReg)
1710 .addReg(0).addImm(0).addReg(0).addImm(TlsOffset).addReg(TlsReg);
1711 } else if (STI.isTargetDarwin()) {
1713 // TlsOffset doesn't fit into a mod r/m byte so we need an extra register.
1714 unsigned ScratchReg2;
1716 if (CompareStackPointer) {
1717 // The primary scratch register is available for holding the TLS offset.
1718 ScratchReg2 = GetScratchRegister(Is64Bit, IsLP64, MF, true);
1719 SaveScratch2 = false;
1721 // Need to use a second register to hold the TLS offset
1722 ScratchReg2 = GetScratchRegister(Is64Bit, IsLP64, MF, false);
1724 // Unfortunately, with fastcc the second scratch register may hold an
1726 SaveScratch2 = MF.getRegInfo().isLiveIn(ScratchReg2);
1729 // If Scratch2 is live-in then it needs to be saved.
1730 assert((!MF.getRegInfo().isLiveIn(ScratchReg2) || SaveScratch2) &&
1731 "Scratch register is live-in and not saved");
1734 BuildMI(checkMBB, DL, TII.get(X86::PUSH32r))
1735 .addReg(ScratchReg2, RegState::Kill);
1737 BuildMI(checkMBB, DL, TII.get(X86::MOV32ri), ScratchReg2)
1739 BuildMI(checkMBB, DL, TII.get(X86::CMP32rm))
1741 .addReg(ScratchReg2).addImm(1).addReg(0)
1746 BuildMI(checkMBB, DL, TII.get(X86::POP32r), ScratchReg2);
1750 // This jump is taken if SP >= (Stacklet Limit + Stack Space required).
1751 // It jumps to normal execution of the function body.
1752 BuildMI(checkMBB, DL, TII.get(X86::JA_1)).addMBB(&prologueMBB);
1754 // On 32 bit we first push the arguments size and then the frame size. On 64
1755 // bit, we pass the stack frame size in r10 and the argument size in r11.
1757 // Functions with nested arguments use R10, so it needs to be saved across
1758 // the call to _morestack
1760 const unsigned RegAX = IsLP64 ? X86::RAX : X86::EAX;
1761 const unsigned Reg10 = IsLP64 ? X86::R10 : X86::R10D;
1762 const unsigned Reg11 = IsLP64 ? X86::R11 : X86::R11D;
1763 const unsigned MOVrr = IsLP64 ? X86::MOV64rr : X86::MOV32rr;
1764 const unsigned MOVri = IsLP64 ? X86::MOV64ri : X86::MOV32ri;
1767 BuildMI(allocMBB, DL, TII.get(MOVrr), RegAX).addReg(Reg10);
1769 BuildMI(allocMBB, DL, TII.get(MOVri), Reg10)
1771 BuildMI(allocMBB, DL, TII.get(MOVri), Reg11)
1772 .addImm(X86FI->getArgumentStackSize());
1773 MF.getRegInfo().setPhysRegUsed(Reg10);
1774 MF.getRegInfo().setPhysRegUsed(Reg11);
1776 BuildMI(allocMBB, DL, TII.get(X86::PUSHi32))
1777 .addImm(X86FI->getArgumentStackSize());
1778 BuildMI(allocMBB, DL, TII.get(X86::PUSHi32))
1782 // __morestack is in libgcc
1783 if (Is64Bit && MF.getTarget().getCodeModel() == CodeModel::Large) {
1784 // Under the large code model, we cannot assume that __morestack lives
1785 // within 2^31 bytes of the call site, so we cannot use pc-relative
1786 // addressing. We cannot perform the call via a temporary register,
1787 // as the rax register may be used to store the static chain, and all
1788 // other suitable registers may be either callee-save or used for
1789 // parameter passing. We cannot use the stack at this point either
1790 // because __morestack manipulates the stack directly.
1792 // To avoid these issues, perform an indirect call via a read-only memory
1793 // location containing the address.
1795 // This solution is not perfect, as it assumes that the .rodata section
1796 // is laid out within 2^31 bytes of each function body, but this seems
1797 // to be sufficient for JIT.
1798 BuildMI(allocMBB, DL, TII.get(X86::CALL64m))
1802 .addExternalSymbol("__morestack_addr")
1804 MF.getMMI().setUsesMorestackAddr(true);
1807 BuildMI(allocMBB, DL, TII.get(X86::CALL64pcrel32))
1808 .addExternalSymbol("__morestack");
1810 BuildMI(allocMBB, DL, TII.get(X86::CALLpcrel32))
1811 .addExternalSymbol("__morestack");
1815 BuildMI(allocMBB, DL, TII.get(X86::MORESTACK_RET_RESTORE_R10));
1817 BuildMI(allocMBB, DL, TII.get(X86::MORESTACK_RET));
1819 allocMBB->addSuccessor(&prologueMBB);
1821 checkMBB->addSuccessor(allocMBB);
1822 checkMBB->addSuccessor(&prologueMBB);
1829 /// Erlang programs may need a special prologue to handle the stack size they
1830 /// might need at runtime. That is because Erlang/OTP does not implement a C
1831 /// stack but uses a custom implementation of hybrid stack/heap architecture.
1832 /// (for more information see Eric Stenman's Ph.D. thesis:
1833 /// http://publications.uu.se/uu/fulltext/nbn_se_uu_diva-2688.pdf)
1836 /// temp0 = sp - MaxStack
1837 /// if( temp0 < SP_LIMIT(P) ) goto IncStack else goto OldStart
1841 /// call inc_stack # doubles the stack space
1842 /// temp0 = sp - MaxStack
1843 /// if( temp0 < SP_LIMIT(P) ) goto IncStack else goto OldStart
1844 void X86FrameLowering::adjustForHiPEPrologue(MachineFunction &MF) const {
1845 const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
1846 const TargetInstrInfo &TII = *STI.getInstrInfo();
1847 MachineFrameInfo *MFI = MF.getFrameInfo();
1848 const unsigned SlotSize = STI.getRegisterInfo()->getSlotSize();
1849 const bool Is64Bit = STI.is64Bit();
1850 const bool IsLP64 = STI.isTarget64BitLP64();
1852 // HiPE-specific values
1853 const unsigned HipeLeafWords = 24;
1854 const unsigned CCRegisteredArgs = Is64Bit ? 6 : 5;
1855 const unsigned Guaranteed = HipeLeafWords * SlotSize;
1856 unsigned CallerStkArity = MF.getFunction()->arg_size() > CCRegisteredArgs ?
1857 MF.getFunction()->arg_size() - CCRegisteredArgs : 0;
1858 unsigned MaxStack = MFI->getStackSize() + CallerStkArity*SlotSize + SlotSize;
1860 assert(STI.isTargetLinux() &&
1861 "HiPE prologue is only supported on Linux operating systems.");
1863 // Compute the largest caller's frame that is needed to fit the callees'
1864 // frames. This 'MaxStack' is computed from:
1866 // a) the fixed frame size, which is the space needed for all spilled temps,
1867 // b) outgoing on-stack parameter areas, and
1868 // c) the minimum stack space this function needs to make available for the
1869 // functions it calls (a tunable ABI property).
1870 if (MFI->hasCalls()) {
1871 unsigned MoreStackForCalls = 0;
1873 for (MachineFunction::iterator MBBI = MF.begin(), MBBE = MF.end();
1874 MBBI != MBBE; ++MBBI)
1875 for (MachineBasicBlock::iterator MI = MBBI->begin(), ME = MBBI->end();
1880 // Get callee operand.
1881 const MachineOperand &MO = MI->getOperand(0);
1883 // Only take account of global function calls (no closures etc.).
1887 const Function *F = dyn_cast<Function>(MO.getGlobal());
1891 // Do not update 'MaxStack' for primitive and built-in functions
1892 // (encoded with names either starting with "erlang."/"bif_" or not
1893 // having a ".", such as a simple <Module>.<Function>.<Arity>, or an
1894 // "_", such as the BIF "suspend_0") as they are executed on another
1896 if (F->getName().find("erlang.") != StringRef::npos ||
1897 F->getName().find("bif_") != StringRef::npos ||
1898 F->getName().find_first_of("._") == StringRef::npos)
1901 unsigned CalleeStkArity =
1902 F->arg_size() > CCRegisteredArgs ? F->arg_size()-CCRegisteredArgs : 0;
1903 if (HipeLeafWords - 1 > CalleeStkArity)
1904 MoreStackForCalls = std::max(MoreStackForCalls,
1905 (HipeLeafWords - 1 - CalleeStkArity) * SlotSize);
1907 MaxStack += MoreStackForCalls;
1910 // If the stack frame needed is larger than the guaranteed then runtime checks
1911 // and calls to "inc_stack_0" BIF should be inserted in the assembly prologue.
1912 if (MaxStack > Guaranteed) {
1913 MachineBasicBlock &prologueMBB = MF.front();
1914 MachineBasicBlock *stackCheckMBB = MF.CreateMachineBasicBlock();
1915 MachineBasicBlock *incStackMBB = MF.CreateMachineBasicBlock();
1917 for (MachineBasicBlock::livein_iterator I = prologueMBB.livein_begin(),
1918 E = prologueMBB.livein_end(); I != E; I++) {
1919 stackCheckMBB->addLiveIn(*I);
1920 incStackMBB->addLiveIn(*I);
1923 MF.push_front(incStackMBB);
1924 MF.push_front(stackCheckMBB);
1926 unsigned ScratchReg, SPReg, PReg, SPLimitOffset;
1927 unsigned LEAop, CMPop, CALLop;
1931 LEAop = X86::LEA64r;
1932 CMPop = X86::CMP64rm;
1933 CALLop = X86::CALL64pcrel32;
1934 SPLimitOffset = 0x90;
1938 LEAop = X86::LEA32r;
1939 CMPop = X86::CMP32rm;
1940 CALLop = X86::CALLpcrel32;
1941 SPLimitOffset = 0x4c;
1944 ScratchReg = GetScratchRegister(Is64Bit, IsLP64, MF, true);
1945 assert(!MF.getRegInfo().isLiveIn(ScratchReg) &&
1946 "HiPE prologue scratch register is live-in");
1948 // Create new MBB for StackCheck:
1949 addRegOffset(BuildMI(stackCheckMBB, DL, TII.get(LEAop), ScratchReg),
1950 SPReg, false, -MaxStack);
1951 // SPLimitOffset is in a fixed heap location (pointed by BP).
1952 addRegOffset(BuildMI(stackCheckMBB, DL, TII.get(CMPop))
1953 .addReg(ScratchReg), PReg, false, SPLimitOffset);
1954 BuildMI(stackCheckMBB, DL, TII.get(X86::JAE_1)).addMBB(&prologueMBB);
1956 // Create new MBB for IncStack:
1957 BuildMI(incStackMBB, DL, TII.get(CALLop)).
1958 addExternalSymbol("inc_stack_0");
1959 addRegOffset(BuildMI(incStackMBB, DL, TII.get(LEAop), ScratchReg),
1960 SPReg, false, -MaxStack);
1961 addRegOffset(BuildMI(incStackMBB, DL, TII.get(CMPop))
1962 .addReg(ScratchReg), PReg, false, SPLimitOffset);
1963 BuildMI(incStackMBB, DL, TII.get(X86::JLE_1)).addMBB(incStackMBB);
1965 stackCheckMBB->addSuccessor(&prologueMBB, 99);
1966 stackCheckMBB->addSuccessor(incStackMBB, 1);
1967 incStackMBB->addSuccessor(&prologueMBB, 99);
1968 incStackMBB->addSuccessor(incStackMBB, 1);
1975 void X86FrameLowering::
1976 eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
1977 MachineBasicBlock::iterator I) const {
1978 const X86Subtarget &STI = MF.getSubtarget<X86Subtarget>();
1979 const TargetInstrInfo &TII = *STI.getInstrInfo();
1980 const X86RegisterInfo &RegInfo = *STI.getRegisterInfo();
1981 unsigned StackPtr = RegInfo.getStackRegister();
1982 bool reserveCallFrame = hasReservedCallFrame(MF);
1983 int Opcode = I->getOpcode();
1984 bool isDestroy = Opcode == TII.getCallFrameDestroyOpcode();
1985 bool IsLP64 = STI.isTarget64BitLP64();
1986 DebugLoc DL = I->getDebugLoc();
1987 uint64_t Amount = !reserveCallFrame ? I->getOperand(0).getImm() : 0;
1988 uint64_t InternalAmt = (isDestroy || Amount) ? I->getOperand(1).getImm() : 0;
1991 if (!reserveCallFrame) {
1992 // If the stack pointer can be changed after prologue, turn the
1993 // adjcallstackup instruction into a 'sub ESP, <amt>' and the
1994 // adjcallstackdown instruction into 'add ESP, <amt>'
1998 // We need to keep the stack aligned properly. To do this, we round the
1999 // amount of space needed for the outgoing arguments up to the next
2000 // alignment boundary.
2001 unsigned StackAlign = getStackAlignment();
2002 Amount = RoundUpToAlignment(Amount, StackAlign);
2004 MachineInstr *New = nullptr;
2006 // Factor out the amount that gets handled inside the sequence
2007 // (Pushes of argument for frame setup, callee pops for frame destroy)
2008 Amount -= InternalAmt;
2011 if (Opcode == TII.getCallFrameSetupOpcode()) {
2012 New = BuildMI(MF, DL, TII.get(getSUBriOpcode(IsLP64, Amount)), StackPtr)
2013 .addReg(StackPtr).addImm(Amount);
2015 assert(Opcode == TII.getCallFrameDestroyOpcode());
2017 unsigned Opc = getADDriOpcode(IsLP64, Amount);
2018 New = BuildMI(MF, DL, TII.get(Opc), StackPtr)
2019 .addReg(StackPtr).addImm(Amount);
2024 // The EFLAGS implicit def is dead.
2025 New->getOperand(3).setIsDead();
2027 // Replace the pseudo instruction with a new instruction.
2034 if (Opcode == TII.getCallFrameDestroyOpcode() && InternalAmt) {
2035 // If we are performing frame pointer elimination and if the callee pops
2036 // something off the stack pointer, add it back. We do this until we have
2037 // more advanced stack pointer tracking ability.
2038 unsigned Opc = getSUBriOpcode(IsLP64, InternalAmt);
2039 MachineInstr *New = BuildMI(MF, DL, TII.get(Opc), StackPtr)
2040 .addReg(StackPtr).addImm(InternalAmt);
2042 // The EFLAGS implicit def is dead.
2043 New->getOperand(3).setIsDead();
2045 // We are not tracking the stack pointer adjustment by the callee, so make
2046 // sure we restore the stack pointer immediately after the call, there may
2047 // be spill code inserted between the CALL and ADJCALLSTACKUP instructions.
2048 MachineBasicBlock::iterator B = MBB.begin();
2049 while (I != B && !std::prev(I)->isCall())