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Introduction: In case when stack alignment is 8 and GPRs parameter part size is not N*8: we add padding to GPRs part, so part's last byte must be recovered at address K*8-1. We need to do it, since remained (stack) part of parameter starts from address K*8, and we need to "attach" "GPRs head" without gaps to it: Stack: |---- 8 bytes block ----| |---- 8 bytes block ----| |---- 8 bytes... [ [padding] [GPRs head] ] [ ------ Tail passed via stack ------ ... FIX: Note, once we added padding we need to correct *all* Arg offsets that are going after padded one. That's why we need this fix: Arg offsets were never corrected before this patch. See new test-cases included in patch. We also don't need to insert padding for byval parameters that are stored in GPRs only. We need pad only last byval parameter and only in case it outsides GPRs and stack alignment = 8. Though, stack area, allocated for recovered byval params, must satisfy "Size mod 8 = 0" restriction. This patch reduces stack usage for some cases: We can reduce ArgRegsSaveArea since inner N*4 bytes sized byval params my be "packed" with alignment 4 in some cases. git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@182237 91177308-0d34-0410-b5e6-96231b3b80d8
410 lines
15 KiB
C++
410 lines
15 KiB
C++
//===-- Thumb1FrameLowering.cpp - Thumb1 Frame Information ----------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file contains the Thumb1 implementation of TargetFrameLowering class.
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//
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//===----------------------------------------------------------------------===//
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#include "Thumb1FrameLowering.h"
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#include "ARMMachineFunctionInfo.h"
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#include "llvm/CodeGen/MachineFrameInfo.h"
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#include "llvm/CodeGen/MachineFunction.h"
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#include "llvm/CodeGen/MachineInstrBuilder.h"
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#include "llvm/CodeGen/MachineRegisterInfo.h"
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using namespace llvm;
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bool Thumb1FrameLowering::hasReservedCallFrame(const MachineFunction &MF) const{
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const MachineFrameInfo *FFI = MF.getFrameInfo();
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unsigned CFSize = FFI->getMaxCallFrameSize();
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// It's not always a good idea to include the call frame as part of the
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// stack frame. ARM (especially Thumb) has small immediate offset to
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// address the stack frame. So a large call frame can cause poor codegen
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// and may even makes it impossible to scavenge a register.
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if (CFSize >= ((1 << 8) - 1) * 4 / 2) // Half of imm8 * 4
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return false;
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return !MF.getFrameInfo()->hasVarSizedObjects();
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}
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static void
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emitSPUpdate(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator &MBBI,
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const TargetInstrInfo &TII, DebugLoc dl,
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const Thumb1RegisterInfo &MRI,
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int NumBytes, unsigned MIFlags = MachineInstr::NoFlags) {
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emitThumbRegPlusImmediate(MBB, MBBI, dl, ARM::SP, ARM::SP, NumBytes, TII,
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MRI, MIFlags);
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}
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void Thumb1FrameLowering::
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eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
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MachineBasicBlock::iterator I) const {
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const Thumb1InstrInfo &TII =
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*static_cast<const Thumb1InstrInfo*>(MF.getTarget().getInstrInfo());
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const Thumb1RegisterInfo *RegInfo =
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static_cast<const Thumb1RegisterInfo*>(MF.getTarget().getRegisterInfo());
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if (!hasReservedCallFrame(MF)) {
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// If we have alloca, convert as follows:
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// ADJCALLSTACKDOWN -> sub, sp, sp, amount
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// ADJCALLSTACKUP -> add, sp, sp, amount
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MachineInstr *Old = I;
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DebugLoc dl = Old->getDebugLoc();
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unsigned Amount = Old->getOperand(0).getImm();
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if (Amount != 0) {
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// We need to keep the stack aligned properly. To do this, we round the
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// amount of space needed for the outgoing arguments up to the next
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// alignment boundary.
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unsigned Align = getStackAlignment();
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Amount = (Amount+Align-1)/Align*Align;
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// Replace the pseudo instruction with a new instruction...
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unsigned Opc = Old->getOpcode();
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if (Opc == ARM::ADJCALLSTACKDOWN || Opc == ARM::tADJCALLSTACKDOWN) {
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emitSPUpdate(MBB, I, TII, dl, *RegInfo, -Amount);
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} else {
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assert(Opc == ARM::ADJCALLSTACKUP || Opc == ARM::tADJCALLSTACKUP);
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emitSPUpdate(MBB, I, TII, dl, *RegInfo, Amount);
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}
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}
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}
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MBB.erase(I);
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}
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void Thumb1FrameLowering::emitPrologue(MachineFunction &MF) const {
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MachineBasicBlock &MBB = MF.front();
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MachineBasicBlock::iterator MBBI = MBB.begin();
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MachineFrameInfo *MFI = MF.getFrameInfo();
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ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
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const Thumb1RegisterInfo *RegInfo =
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static_cast<const Thumb1RegisterInfo*>(MF.getTarget().getRegisterInfo());
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const Thumb1InstrInfo &TII =
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*static_cast<const Thumb1InstrInfo*>(MF.getTarget().getInstrInfo());
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unsigned Align = MF.getTarget().getFrameLowering()->getStackAlignment();
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unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize(Align);
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unsigned NumBytes = MFI->getStackSize();
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const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
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DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
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unsigned FramePtr = RegInfo->getFrameRegister(MF);
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unsigned BasePtr = RegInfo->getBaseRegister();
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// Thumb add/sub sp, imm8 instructions implicitly multiply the offset by 4.
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NumBytes = (NumBytes + 3) & ~3;
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MFI->setStackSize(NumBytes);
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// Determine the sizes of each callee-save spill areas and record which frame
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// belongs to which callee-save spill areas.
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unsigned GPRCS1Size = 0, GPRCS2Size = 0, DPRCSSize = 0;
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int FramePtrSpillFI = 0;
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if (ArgRegsSaveSize)
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emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, -ArgRegsSaveSize,
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MachineInstr::FrameSetup);
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if (!AFI->hasStackFrame()) {
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if (NumBytes != 0)
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emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, -NumBytes,
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MachineInstr::FrameSetup);
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return;
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}
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for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
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unsigned Reg = CSI[i].getReg();
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int FI = CSI[i].getFrameIdx();
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switch (Reg) {
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case ARM::R4:
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case ARM::R5:
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case ARM::R6:
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case ARM::R7:
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case ARM::LR:
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if (Reg == FramePtr)
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FramePtrSpillFI = FI;
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AFI->addGPRCalleeSavedArea1Frame(FI);
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GPRCS1Size += 4;
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break;
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case ARM::R8:
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case ARM::R9:
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case ARM::R10:
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case ARM::R11:
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if (Reg == FramePtr)
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FramePtrSpillFI = FI;
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if (STI.isTargetIOS()) {
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AFI->addGPRCalleeSavedArea2Frame(FI);
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GPRCS2Size += 4;
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} else {
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AFI->addGPRCalleeSavedArea1Frame(FI);
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GPRCS1Size += 4;
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}
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break;
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default:
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AFI->addDPRCalleeSavedAreaFrame(FI);
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DPRCSSize += 8;
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}
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}
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if (MBBI != MBB.end() && MBBI->getOpcode() == ARM::tPUSH) {
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++MBBI;
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if (MBBI != MBB.end())
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dl = MBBI->getDebugLoc();
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}
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// Determine starting offsets of spill areas.
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unsigned DPRCSOffset = NumBytes - (GPRCS1Size + GPRCS2Size + DPRCSSize);
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unsigned GPRCS2Offset = DPRCSOffset + DPRCSSize;
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unsigned GPRCS1Offset = GPRCS2Offset + GPRCS2Size;
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bool HasFP = hasFP(MF);
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if (HasFP)
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AFI->setFramePtrSpillOffset(MFI->getObjectOffset(FramePtrSpillFI) +
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NumBytes);
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AFI->setGPRCalleeSavedArea1Offset(GPRCS1Offset);
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AFI->setGPRCalleeSavedArea2Offset(GPRCS2Offset);
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AFI->setDPRCalleeSavedAreaOffset(DPRCSOffset);
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NumBytes = DPRCSOffset;
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// Adjust FP so it point to the stack slot that contains the previous FP.
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if (HasFP) {
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AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tADDrSPi), FramePtr)
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.addFrameIndex(FramePtrSpillFI).addImm(0)
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.setMIFlags(MachineInstr::FrameSetup));
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if (NumBytes > 508)
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// If offset is > 508 then sp cannot be adjusted in a single instruction,
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// try restoring from fp instead.
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AFI->setShouldRestoreSPFromFP(true);
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}
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if (NumBytes)
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// Insert it after all the callee-save spills.
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emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, -NumBytes,
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MachineInstr::FrameSetup);
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if (STI.isTargetELF() && HasFP)
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MFI->setOffsetAdjustment(MFI->getOffsetAdjustment() -
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AFI->getFramePtrSpillOffset());
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AFI->setGPRCalleeSavedArea1Size(GPRCS1Size);
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AFI->setGPRCalleeSavedArea2Size(GPRCS2Size);
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AFI->setDPRCalleeSavedAreaSize(DPRCSSize);
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// Thumb1 does not currently support dynamic stack realignment. Report a
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// fatal error rather then silently generate bad code.
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if (RegInfo->needsStackRealignment(MF))
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report_fatal_error("Dynamic stack realignment not supported for thumb1.");
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// If we need a base pointer, set it up here. It's whatever the value
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// of the stack pointer is at this point. Any variable size objects
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// will be allocated after this, so we can still use the base pointer
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// to reference locals.
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if (RegInfo->hasBasePointer(MF))
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AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr), BasePtr)
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.addReg(ARM::SP));
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// If the frame has variable sized objects then the epilogue must restore
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// the sp from fp. We can assume there's an FP here since hasFP already
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// checks for hasVarSizedObjects.
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if (MFI->hasVarSizedObjects())
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AFI->setShouldRestoreSPFromFP(true);
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}
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static bool isCalleeSavedRegister(unsigned Reg, const uint16_t *CSRegs) {
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for (unsigned i = 0; CSRegs[i]; ++i)
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if (Reg == CSRegs[i])
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return true;
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return false;
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}
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static bool isCSRestore(MachineInstr *MI, const uint16_t *CSRegs) {
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if (MI->getOpcode() == ARM::tLDRspi &&
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MI->getOperand(1).isFI() &&
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isCalleeSavedRegister(MI->getOperand(0).getReg(), CSRegs))
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return true;
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else if (MI->getOpcode() == ARM::tPOP) {
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// The first two operands are predicates. The last two are
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// imp-def and imp-use of SP. Check everything in between.
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for (int i = 2, e = MI->getNumOperands() - 2; i != e; ++i)
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if (!isCalleeSavedRegister(MI->getOperand(i).getReg(), CSRegs))
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return false;
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return true;
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}
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return false;
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}
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void Thumb1FrameLowering::emitEpilogue(MachineFunction &MF,
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MachineBasicBlock &MBB) const {
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MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
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assert((MBBI->getOpcode() == ARM::tBX_RET ||
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MBBI->getOpcode() == ARM::tPOP_RET) &&
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"Can only insert epilog into returning blocks");
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DebugLoc dl = MBBI->getDebugLoc();
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MachineFrameInfo *MFI = MF.getFrameInfo();
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ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
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const Thumb1RegisterInfo *RegInfo =
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static_cast<const Thumb1RegisterInfo*>(MF.getTarget().getRegisterInfo());
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const Thumb1InstrInfo &TII =
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*static_cast<const Thumb1InstrInfo*>(MF.getTarget().getInstrInfo());
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unsigned Align = MF.getTarget().getFrameLowering()->getStackAlignment();
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unsigned ArgRegsSaveSize = AFI->getArgRegsSaveSize(Align);
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int NumBytes = (int)MFI->getStackSize();
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const uint16_t *CSRegs = RegInfo->getCalleeSavedRegs();
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unsigned FramePtr = RegInfo->getFrameRegister(MF);
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if (!AFI->hasStackFrame()) {
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if (NumBytes != 0)
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emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, NumBytes);
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} else {
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// Unwind MBBI to point to first LDR / VLDRD.
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if (MBBI != MBB.begin()) {
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do
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--MBBI;
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while (MBBI != MBB.begin() && isCSRestore(MBBI, CSRegs));
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if (!isCSRestore(MBBI, CSRegs))
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++MBBI;
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}
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// Move SP to start of FP callee save spill area.
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NumBytes -= (AFI->getGPRCalleeSavedArea1Size() +
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AFI->getGPRCalleeSavedArea2Size() +
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AFI->getDPRCalleeSavedAreaSize());
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if (AFI->shouldRestoreSPFromFP()) {
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NumBytes = AFI->getFramePtrSpillOffset() - NumBytes;
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// Reset SP based on frame pointer only if the stack frame extends beyond
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// frame pointer stack slot, the target is ELF and the function has FP, or
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// the target uses var sized objects.
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if (NumBytes) {
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assert(MF.getRegInfo().isPhysRegUsed(ARM::R4) &&
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"No scratch register to restore SP from FP!");
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emitThumbRegPlusImmediate(MBB, MBBI, dl, ARM::R4, FramePtr, -NumBytes,
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TII, *RegInfo);
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AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr),
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ARM::SP)
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.addReg(ARM::R4));
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} else
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AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tMOVr),
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ARM::SP)
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.addReg(FramePtr));
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} else {
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if (MBBI->getOpcode() == ARM::tBX_RET &&
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&MBB.front() != MBBI &&
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prior(MBBI)->getOpcode() == ARM::tPOP) {
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MachineBasicBlock::iterator PMBBI = prior(MBBI);
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emitSPUpdate(MBB, PMBBI, TII, dl, *RegInfo, NumBytes);
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} else
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emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, NumBytes);
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}
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}
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if (ArgRegsSaveSize) {
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// Unlike T2 and ARM mode, the T1 pop instruction cannot restore
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// to LR, and we can't pop the value directly to the PC since
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// we need to update the SP after popping the value. Therefore, we
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// pop the old LR into R3 as a temporary.
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// Move back past the callee-saved register restoration
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while (MBBI != MBB.end() && isCSRestore(MBBI, CSRegs))
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++MBBI;
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// Epilogue for vararg functions: pop LR to R3 and branch off it.
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AddDefaultPred(BuildMI(MBB, MBBI, dl, TII.get(ARM::tPOP)))
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.addReg(ARM::R3, RegState::Define);
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emitSPUpdate(MBB, MBBI, TII, dl, *RegInfo, ArgRegsSaveSize);
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MachineInstrBuilder MIB =
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BuildMI(MBB, MBBI, dl, TII.get(ARM::tBX_RET_vararg))
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.addReg(ARM::R3, RegState::Kill);
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AddDefaultPred(MIB);
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MIB.copyImplicitOps(&*MBBI);
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// erase the old tBX_RET instruction
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MBB.erase(MBBI);
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}
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}
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bool Thumb1FrameLowering::
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spillCalleeSavedRegisters(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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const std::vector<CalleeSavedInfo> &CSI,
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const TargetRegisterInfo *TRI) const {
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if (CSI.empty())
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return false;
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DebugLoc DL;
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MachineFunction &MF = *MBB.getParent();
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const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
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if (MI != MBB.end()) DL = MI->getDebugLoc();
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MachineInstrBuilder MIB = BuildMI(MBB, MI, DL, TII.get(ARM::tPUSH));
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AddDefaultPred(MIB);
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for (unsigned i = CSI.size(); i != 0; --i) {
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unsigned Reg = CSI[i-1].getReg();
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bool isKill = true;
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// Add the callee-saved register as live-in unless it's LR and
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// @llvm.returnaddress is called. If LR is returned for @llvm.returnaddress
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// then it's already added to the function and entry block live-in sets.
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if (Reg == ARM::LR) {
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MachineFunction &MF = *MBB.getParent();
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if (MF.getFrameInfo()->isReturnAddressTaken() &&
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MF.getRegInfo().isLiveIn(Reg))
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isKill = false;
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}
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if (isKill)
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MBB.addLiveIn(Reg);
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MIB.addReg(Reg, getKillRegState(isKill));
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}
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MIB.setMIFlags(MachineInstr::FrameSetup);
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return true;
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}
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bool Thumb1FrameLowering::
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restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
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MachineBasicBlock::iterator MI,
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const std::vector<CalleeSavedInfo> &CSI,
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const TargetRegisterInfo *TRI) const {
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if (CSI.empty())
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return false;
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MachineFunction &MF = *MBB.getParent();
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ARMFunctionInfo *AFI = MF.getInfo<ARMFunctionInfo>();
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const TargetInstrInfo &TII = *MF.getTarget().getInstrInfo();
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bool isVarArg = AFI->getArgRegsSaveSize() > 0;
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DebugLoc DL = MI->getDebugLoc();
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MachineInstrBuilder MIB = BuildMI(MF, DL, TII.get(ARM::tPOP));
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AddDefaultPred(MIB);
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bool NumRegs = false;
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for (unsigned i = CSI.size(); i != 0; --i) {
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unsigned Reg = CSI[i-1].getReg();
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if (Reg == ARM::LR) {
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// Special epilogue for vararg functions. See emitEpilogue
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if (isVarArg)
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continue;
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Reg = ARM::PC;
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(*MIB).setDesc(TII.get(ARM::tPOP_RET));
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MIB.copyImplicitOps(&*MI);
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MI = MBB.erase(MI);
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}
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MIB.addReg(Reg, getDefRegState(true));
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NumRegs = true;
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}
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// It's illegal to emit pop instruction without operands.
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if (NumRegs)
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MBB.insert(MI, &*MIB);
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else
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MF.DeleteMachineInstr(MIB);
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return true;
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}
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