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llvm-project/llvm/lib/Target/PowerPC/PPCFrameLowering.cpp

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//===-- PPCFrameLowering.cpp - PPC Frame Information ----------------------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file contains the PPC implementation of TargetFrameLowering class.
//
//===----------------------------------------------------------------------===//
#include "PPCFrameLowering.h"
#include "PPCInstrBuilder.h"
#include "PPCInstrInfo.h"
#include "PPCMachineFunctionInfo.h"
#include "PPCSubtarget.h"
#include "PPCTargetMachine.h"
#include "llvm/CodeGen/MachineFrameInfo.h"
#include "llvm/CodeGen/MachineFunction.h"
#include "llvm/CodeGen/MachineInstrBuilder.h"
#include "llvm/CodeGen/MachineModuleInfo.h"
#include "llvm/CodeGen/MachineRegisterInfo.h"
#include "llvm/CodeGen/RegisterScavenging.h"
#include "llvm/IR/Function.h"
#include "llvm/Target/TargetOptions.h"
using namespace llvm;
/// VRRegNo - Map from a numbered VR register to its enum value.
///
static const MCPhysReg VRRegNo[] = {
PPC::V0 , PPC::V1 , PPC::V2 , PPC::V3 , PPC::V4 , PPC::V5 , PPC::V6 , PPC::V7 ,
PPC::V8 , PPC::V9 , PPC::V10, PPC::V11, PPC::V12, PPC::V13, PPC::V14, PPC::V15,
PPC::V16, PPC::V17, PPC::V18, PPC::V19, PPC::V20, PPC::V21, PPC::V22, PPC::V23,
PPC::V24, PPC::V25, PPC::V26, PPC::V27, PPC::V28, PPC::V29, PPC::V30, PPC::V31
};
static unsigned computeReturnSaveOffset(const PPCSubtarget &STI) {
if (STI.isDarwinABI())
return STI.isPPC64() ? 16 : 8;
// SVR4 ABI:
return STI.isPPC64() ? 16 : 4;
}
static unsigned computeTOCSaveOffset(const PPCSubtarget &STI) {
return STI.isELFv2ABI() ? 24 : 40;
}
static unsigned computeFramePointerSaveOffset(const PPCSubtarget &STI) {
// For the Darwin ABI:
// We cannot use the TOC save slot (offset +20) in the PowerPC linkage area
// for saving the frame pointer (if needed.) While the published ABI has
// not used this slot since at least MacOSX 10.2, there is older code
// around that does use it, and that needs to continue to work.
if (STI.isDarwinABI())
return STI.isPPC64() ? -8U : -4U;
// SVR4 ABI: First slot in the general register save area.
return STI.isPPC64() ? -8U : -4U;
}
static unsigned computeLinkageSize(const PPCSubtarget &STI) {
if (STI.isDarwinABI() || STI.isPPC64())
return (STI.isELFv2ABI() ? 4 : 6) * (STI.isPPC64() ? 8 : 4);
// SVR4 ABI:
return 8;
}
static unsigned computeBasePointerSaveOffset(const PPCSubtarget &STI) {
if (STI.isDarwinABI())
return STI.isPPC64() ? -16U : -8U;
// SVR4 ABI: First slot in the general register save area.
return STI.isPPC64()
? -16U
: (STI.getTargetMachine().getRelocationModel() == Reloc::PIC_)
? -12U
: -8U;
}
PPCFrameLowering::PPCFrameLowering(const PPCSubtarget &STI)
: TargetFrameLowering(TargetFrameLowering::StackGrowsDown,
STI.getPlatformStackAlignment(), 0),
Subtarget(STI), ReturnSaveOffset(computeReturnSaveOffset(Subtarget)),
TOCSaveOffset(computeTOCSaveOffset(Subtarget)),
FramePointerSaveOffset(computeFramePointerSaveOffset(Subtarget)),
LinkageSize(computeLinkageSize(Subtarget)),
BasePointerSaveOffset(computeBasePointerSaveOffset(STI)) {}
// With the SVR4 ABI, callee-saved registers have fixed offsets on the stack.
const PPCFrameLowering::SpillSlot *PPCFrameLowering::getCalleeSavedSpillSlots(
unsigned &NumEntries) const {
if (Subtarget.isDarwinABI()) {
NumEntries = 1;
if (Subtarget.isPPC64()) {
static const SpillSlot darwin64Offsets = {PPC::X31, -8};
return &darwin64Offsets;
} else {
static const SpillSlot darwinOffsets = {PPC::R31, -4};
return &darwinOffsets;
}
}
// Early exit if not using the SVR4 ABI.
if (!Subtarget.isSVR4ABI()) {
NumEntries = 0;
return nullptr;
}
// Note that the offsets here overlap, but this is fixed up in
// processFunctionBeforeFrameFinalized.
static const SpillSlot Offsets[] = {
// Floating-point register save area offsets.
{PPC::F31, -8},
{PPC::F30, -16},
{PPC::F29, -24},
{PPC::F28, -32},
{PPC::F27, -40},
{PPC::F26, -48},
{PPC::F25, -56},
{PPC::F24, -64},
{PPC::F23, -72},
{PPC::F22, -80},
{PPC::F21, -88},
{PPC::F20, -96},
{PPC::F19, -104},
{PPC::F18, -112},
{PPC::F17, -120},
{PPC::F16, -128},
{PPC::F15, -136},
{PPC::F14, -144},
// General register save area offsets.
{PPC::R31, -4},
{PPC::R30, -8},
{PPC::R29, -12},
{PPC::R28, -16},
{PPC::R27, -20},
{PPC::R26, -24},
{PPC::R25, -28},
{PPC::R24, -32},
{PPC::R23, -36},
{PPC::R22, -40},
{PPC::R21, -44},
{PPC::R20, -48},
{PPC::R19, -52},
{PPC::R18, -56},
{PPC::R17, -60},
{PPC::R16, -64},
{PPC::R15, -68},
{PPC::R14, -72},
// CR save area offset. We map each of the nonvolatile CR fields
// to the slot for CR2, which is the first of the nonvolatile CR
// fields to be assigned, so that we only allocate one save slot.
// See PPCRegisterInfo::hasReservedSpillSlot() for more information.
{PPC::CR2, -4},
// VRSAVE save area offset.
{PPC::VRSAVE, -4},
// Vector register save area
{PPC::V31, -16},
{PPC::V30, -32},
{PPC::V29, -48},
{PPC::V28, -64},
{PPC::V27, -80},
{PPC::V26, -96},
{PPC::V25, -112},
{PPC::V24, -128},
{PPC::V23, -144},
{PPC::V22, -160},
{PPC::V21, -176},
{PPC::V20, -192}};
static const SpillSlot Offsets64[] = {
// Floating-point register save area offsets.
{PPC::F31, -8},
{PPC::F30, -16},
{PPC::F29, -24},
{PPC::F28, -32},
{PPC::F27, -40},
{PPC::F26, -48},
{PPC::F25, -56},
{PPC::F24, -64},
{PPC::F23, -72},
{PPC::F22, -80},
{PPC::F21, -88},
{PPC::F20, -96},
{PPC::F19, -104},
{PPC::F18, -112},
{PPC::F17, -120},
{PPC::F16, -128},
{PPC::F15, -136},
{PPC::F14, -144},
// General register save area offsets.
{PPC::X31, -8},
{PPC::X30, -16},
{PPC::X29, -24},
{PPC::X28, -32},
{PPC::X27, -40},
{PPC::X26, -48},
{PPC::X25, -56},
{PPC::X24, -64},
{PPC::X23, -72},
{PPC::X22, -80},
{PPC::X21, -88},
{PPC::X20, -96},
{PPC::X19, -104},
{PPC::X18, -112},
{PPC::X17, -120},
{PPC::X16, -128},
{PPC::X15, -136},
{PPC::X14, -144},
// VRSAVE save area offset.
{PPC::VRSAVE, -4},
// Vector register save area
{PPC::V31, -16},
{PPC::V30, -32},
{PPC::V29, -48},
{PPC::V28, -64},
{PPC::V27, -80},
{PPC::V26, -96},
{PPC::V25, -112},
{PPC::V24, -128},
{PPC::V23, -144},
{PPC::V22, -160},
{PPC::V21, -176},
{PPC::V20, -192}};
if (Subtarget.isPPC64()) {
NumEntries = array_lengthof(Offsets64);
return Offsets64;
} else {
NumEntries = array_lengthof(Offsets);
return Offsets;
}
}
/// RemoveVRSaveCode - We have found that this function does not need any code
/// to manipulate the VRSAVE register, even though it uses vector registers.
/// This can happen when the only registers used are known to be live in or out
/// of the function. Remove all of the VRSAVE related code from the function.
/// FIXME: The removal of the code results in a compile failure at -O0 when the
/// function contains a function call, as the GPR containing original VRSAVE
/// contents is spilled and reloaded around the call. Without the prolog code,
/// the spill instruction refers to an undefined register. This code needs
/// to account for all uses of that GPR.
static void RemoveVRSaveCode(MachineInstr *MI) {
MachineBasicBlock *Entry = MI->getParent();
MachineFunction *MF = Entry->getParent();
// We know that the MTVRSAVE instruction immediately follows MI. Remove it.
MachineBasicBlock::iterator MBBI = MI;
++MBBI;
assert(MBBI != Entry->end() && MBBI->getOpcode() == PPC::MTVRSAVE);
MBBI->eraseFromParent();
bool RemovedAllMTVRSAVEs = true;
// See if we can find and remove the MTVRSAVE instruction from all of the
// epilog blocks.
for (MachineFunction::iterator I = MF->begin(), E = MF->end(); I != E; ++I) {
// If last instruction is a return instruction, add an epilogue
if (I->isReturnBlock()) {
bool FoundIt = false;
for (MBBI = I->end(); MBBI != I->begin(); ) {
--MBBI;
if (MBBI->getOpcode() == PPC::MTVRSAVE) {
MBBI->eraseFromParent(); // remove it.
FoundIt = true;
break;
}
}
RemovedAllMTVRSAVEs &= FoundIt;
}
}
// If we found and removed all MTVRSAVE instructions, remove the read of
// VRSAVE as well.
if (RemovedAllMTVRSAVEs) {
MBBI = MI;
assert(MBBI != Entry->begin() && "UPDATE_VRSAVE is first instr in block?");
--MBBI;
assert(MBBI->getOpcode() == PPC::MFVRSAVE && "VRSAVE instrs wandered?");
MBBI->eraseFromParent();
}
// Finally, nuke the UPDATE_VRSAVE.
MI->eraseFromParent();
}
// HandleVRSaveUpdate - MI is the UPDATE_VRSAVE instruction introduced by the
// instruction selector. Based on the vector registers that have been used,
// transform this into the appropriate ORI instruction.
static void HandleVRSaveUpdate(MachineInstr *MI, const TargetInstrInfo &TII) {
MachineFunction *MF = MI->getParent()->getParent();
const TargetRegisterInfo *TRI = MF->getSubtarget().getRegisterInfo();
DebugLoc dl = MI->getDebugLoc();
const MachineRegisterInfo &MRI = MF->getRegInfo();
unsigned UsedRegMask = 0;
for (unsigned i = 0; i != 32; ++i)
if (MRI.isPhysRegModified(VRRegNo[i]))
UsedRegMask |= 1 << (31-i);
// Live in and live out values already must be in the mask, so don't bother
// marking them.
for (MachineRegisterInfo::livein_iterator
I = MF->getRegInfo().livein_begin(),
E = MF->getRegInfo().livein_end(); I != E; ++I) {
unsigned RegNo = TRI->getEncodingValue(I->first);
if (VRRegNo[RegNo] == I->first) // If this really is a vector reg.
UsedRegMask &= ~(1 << (31-RegNo)); // Doesn't need to be marked.
}
// Live out registers appear as use operands on return instructions.
for (MachineFunction::const_iterator BI = MF->begin(), BE = MF->end();
UsedRegMask != 0 && BI != BE; ++BI) {
const MachineBasicBlock &MBB = *BI;
if (!MBB.isReturnBlock())
continue;
const MachineInstr &Ret = MBB.back();
for (unsigned I = 0, E = Ret.getNumOperands(); I != E; ++I) {
const MachineOperand &MO = Ret.getOperand(I);
if (!MO.isReg() || !PPC::VRRCRegClass.contains(MO.getReg()))
continue;
unsigned RegNo = TRI->getEncodingValue(MO.getReg());
UsedRegMask &= ~(1 << (31-RegNo));
}
}
// If no registers are used, turn this into a copy.
if (UsedRegMask == 0) {
// Remove all VRSAVE code.
RemoveVRSaveCode(MI);
return;
}
unsigned SrcReg = MI->getOperand(1).getReg();
unsigned DstReg = MI->getOperand(0).getReg();
if ((UsedRegMask & 0xFFFF) == UsedRegMask) {
if (DstReg != SrcReg)
BuildMI(*MI->getParent(), MI, dl, TII.get(PPC::ORI), DstReg)
.addReg(SrcReg)
.addImm(UsedRegMask);
else
BuildMI(*MI->getParent(), MI, dl, TII.get(PPC::ORI), DstReg)
.addReg(SrcReg, RegState::Kill)
.addImm(UsedRegMask);
} else if ((UsedRegMask & 0xFFFF0000) == UsedRegMask) {
if (DstReg != SrcReg)
BuildMI(*MI->getParent(), MI, dl, TII.get(PPC::ORIS), DstReg)
.addReg(SrcReg)
.addImm(UsedRegMask >> 16);
else
BuildMI(*MI->getParent(), MI, dl, TII.get(PPC::ORIS), DstReg)
.addReg(SrcReg, RegState::Kill)
.addImm(UsedRegMask >> 16);
} else {
if (DstReg != SrcReg)
BuildMI(*MI->getParent(), MI, dl, TII.get(PPC::ORIS), DstReg)
.addReg(SrcReg)
.addImm(UsedRegMask >> 16);
else
BuildMI(*MI->getParent(), MI, dl, TII.get(PPC::ORIS), DstReg)
.addReg(SrcReg, RegState::Kill)
.addImm(UsedRegMask >> 16);
BuildMI(*MI->getParent(), MI, dl, TII.get(PPC::ORI), DstReg)
.addReg(DstReg, RegState::Kill)
.addImm(UsedRegMask & 0xFFFF);
}
// Remove the old UPDATE_VRSAVE instruction.
MI->eraseFromParent();
}
static bool spillsCR(const MachineFunction &MF) {
const PPCFunctionInfo *FuncInfo = MF.getInfo<PPCFunctionInfo>();
return FuncInfo->isCRSpilled();
}
static bool spillsVRSAVE(const MachineFunction &MF) {
const PPCFunctionInfo *FuncInfo = MF.getInfo<PPCFunctionInfo>();
return FuncInfo->isVRSAVESpilled();
}
static bool hasSpills(const MachineFunction &MF) {
const PPCFunctionInfo *FuncInfo = MF.getInfo<PPCFunctionInfo>();
return FuncInfo->hasSpills();
}
static bool hasNonRISpills(const MachineFunction &MF) {
const PPCFunctionInfo *FuncInfo = MF.getInfo<PPCFunctionInfo>();
return FuncInfo->hasNonRISpills();
}
/// MustSaveLR - Return true if this function requires that we save the LR
/// register onto the stack in the prolog and restore it in the epilog of the
/// function.
static bool MustSaveLR(const MachineFunction &MF, unsigned LR) {
const PPCFunctionInfo *MFI = MF.getInfo<PPCFunctionInfo>();
// We need a save/restore of LR if there is any def of LR (which is
// defined by calls, including the PIC setup sequence), or if there is
// some use of the LR stack slot (e.g. for builtin_return_address).
// (LR comes in 32 and 64 bit versions.)
MachineRegisterInfo::def_iterator RI = MF.getRegInfo().def_begin(LR);
return RI !=MF.getRegInfo().def_end() || MFI->isLRStoreRequired();
}
/// determineFrameLayout - Determine the size of the frame and maximum call
/// frame size.
unsigned PPCFrameLowering::determineFrameLayout(MachineFunction &MF,
bool UpdateMF,
bool UseEstimate) const {
MachineFrameInfo *MFI = MF.getFrameInfo();
// Get the number of bytes to allocate from the FrameInfo
unsigned FrameSize =
UseEstimate ? MFI->estimateStackSize(MF) : MFI->getStackSize();
// Get stack alignments. The frame must be aligned to the greatest of these:
unsigned TargetAlign = getStackAlignment(); // alignment required per the ABI
unsigned MaxAlign = MFI->getMaxAlignment(); // algmt required by data in frame
unsigned AlignMask = std::max(MaxAlign, TargetAlign) - 1;
const PPCRegisterInfo *RegInfo =
static_cast<const PPCRegisterInfo *>(Subtarget.getRegisterInfo());
// If we are a leaf function, and use up to 224 bytes of stack space,
// don't have a frame pointer, calls, or dynamic alloca then we do not need
// to adjust the stack pointer (we fit in the Red Zone).
// The 32-bit SVR4 ABI has no Red Zone. However, it can still generate
// stackless code if all local vars are reg-allocated.
bool DisableRedZone = MF.getFunction()->hasFnAttribute(Attribute::NoRedZone);
unsigned LR = RegInfo->getRARegister();
if (!DisableRedZone &&
(Subtarget.isPPC64() || // 32-bit SVR4, no stack-
!Subtarget.isSVR4ABI() || // allocated locals.
FrameSize == 0) &&
FrameSize <= 224 && // Fits in red zone.
!MFI->hasVarSizedObjects() && // No dynamic alloca.
!MFI->adjustsStack() && // No calls.
!MustSaveLR(MF, LR) &&
!RegInfo->hasBasePointer(MF)) { // No special alignment.
// No need for frame
if (UpdateMF)
MFI->setStackSize(0);
return 0;
}
// Get the maximum call frame size of all the calls.
unsigned maxCallFrameSize = MFI->getMaxCallFrameSize();
// Maximum call frame needs to be at least big enough for linkage area.
unsigned minCallFrameSize = getLinkageSize();
maxCallFrameSize = std::max(maxCallFrameSize, minCallFrameSize);
// If we have dynamic alloca then maxCallFrameSize needs to be aligned so
// that allocations will be aligned.
if (MFI->hasVarSizedObjects())
maxCallFrameSize = (maxCallFrameSize + AlignMask) & ~AlignMask;
// Update maximum call frame size.
if (UpdateMF)
MFI->setMaxCallFrameSize(maxCallFrameSize);
// Include call frame size in total.
FrameSize += maxCallFrameSize;
// Make sure the frame is aligned.
FrameSize = (FrameSize + AlignMask) & ~AlignMask;
// Update frame info.
if (UpdateMF)
MFI->setStackSize(FrameSize);
return FrameSize;
}
// hasFP - Return true if the specified function actually has a dedicated frame
// pointer register.
bool PPCFrameLowering::hasFP(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
// FIXME: This is pretty much broken by design: hasFP() might be called really
// early, before the stack layout was calculated and thus hasFP() might return
// true or false here depending on the time of call.
return (MFI->getStackSize()) && needsFP(MF);
}
// needsFP - Return true if the specified function should have a dedicated frame
// pointer register. This is true if the function has variable sized allocas or
// if frame pointer elimination is disabled.
bool PPCFrameLowering::needsFP(const MachineFunction &MF) const {
const MachineFrameInfo *MFI = MF.getFrameInfo();
// Naked functions have no stack frame pushed, so we don't have a frame
// pointer.
if (MF.getFunction()->hasFnAttribute(Attribute::Naked))
return false;
return MF.getTarget().Options.DisableFramePointerElim(MF) ||
MFI->hasVarSizedObjects() ||
MFI->hasStackMap() || MFI->hasPatchPoint() ||
(MF.getTarget().Options.GuaranteedTailCallOpt &&
MF.getInfo<PPCFunctionInfo>()->hasFastCall());
}
void PPCFrameLowering::replaceFPWithRealFP(MachineFunction &MF) const {
bool is31 = needsFP(MF);
unsigned FPReg = is31 ? PPC::R31 : PPC::R1;
unsigned FP8Reg = is31 ? PPC::X31 : PPC::X1;
const PPCRegisterInfo *RegInfo =
static_cast<const PPCRegisterInfo *>(Subtarget.getRegisterInfo());
bool HasBP = RegInfo->hasBasePointer(MF);
unsigned BPReg = HasBP ? (unsigned) RegInfo->getBaseRegister(MF) : FPReg;
unsigned BP8Reg = HasBP ? (unsigned) PPC::X30 : FPReg;
for (MachineFunction::iterator BI = MF.begin(), BE = MF.end();
BI != BE; ++BI)
for (MachineBasicBlock::iterator MBBI = BI->end(); MBBI != BI->begin(); ) {
--MBBI;
for (unsigned I = 0, E = MBBI->getNumOperands(); I != E; ++I) {
MachineOperand &MO = MBBI->getOperand(I);
if (!MO.isReg())
continue;
switch (MO.getReg()) {
case PPC::FP:
MO.setReg(FPReg);
break;
case PPC::FP8:
MO.setReg(FP8Reg);
break;
case PPC::BP:
MO.setReg(BPReg);
break;
case PPC::BP8:
MO.setReg(BP8Reg);
break;
}
}
}
}
bool PPCFrameLowering::findScratchRegister(MachineBasicBlock *MBB,
bool UseAtEnd,
unsigned *ScratchRegister) const {
RegScavenger RS;
unsigned R0 = Subtarget.isPPC64() ? PPC::X0 : PPC::R0;
if (ScratchRegister)
*ScratchRegister = R0;
// If MBB is an entry or exit block, use R0 as the scratch register
if ((UseAtEnd && MBB->isReturnBlock()) ||
(!UseAtEnd && (&MBB->getParent()->front() == MBB)))
return true;
RS.enterBasicBlock(MBB);
if (UseAtEnd && !MBB->empty()) {
// The scratch register will be used at the end of the block, so must consider
// all registers used within the block
MachineBasicBlock::iterator MBBI = MBB->getFirstTerminator();
// If no terminator, back iterator up to previous instruction.
if (MBBI == MBB->end())
MBBI = std::prev(MBBI);
if (MBBI != MBB->begin())
RS.forward(MBBI);
}
if (!RS.isRegUsed(R0))
return true;
unsigned Reg = RS.FindUnusedReg(Subtarget.isPPC64() ? &PPC::G8RCRegClass
: &PPC::GPRCRegClass);
// Make sure the register scavenger was able to find an available register
// If not, use R0 but return false to indicate no register was available and
// R0 must be used (as recommended by the ABI)
if (Reg == 0)
return false;
if (ScratchRegister)
*ScratchRegister = Reg;
return true;
}
bool PPCFrameLowering::canUseAsPrologue(const MachineBasicBlock &MBB) const {
MachineBasicBlock *TmpMBB = const_cast<MachineBasicBlock *>(&MBB);
return findScratchRegister(TmpMBB, false, nullptr);
}
bool PPCFrameLowering::canUseAsEpilogue(const MachineBasicBlock &MBB) const {
MachineBasicBlock *TmpMBB = const_cast<MachineBasicBlock *>(&MBB);
return findScratchRegister(TmpMBB, true, nullptr);
}
void PPCFrameLowering::emitPrologue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = MBB.begin();
MachineFrameInfo *MFI = MF.getFrameInfo();
const PPCInstrInfo &TII =
*static_cast<const PPCInstrInfo *>(Subtarget.getInstrInfo());
const PPCRegisterInfo *RegInfo =
static_cast<const PPCRegisterInfo *>(Subtarget.getRegisterInfo());
MachineModuleInfo &MMI = MF.getMMI();
const MCRegisterInfo *MRI = MMI.getContext().getRegisterInfo();
DebugLoc dl;
bool needsCFI = MMI.hasDebugInfo() ||
MF.getFunction()->needsUnwindTableEntry();
// Get processor type.
bool isPPC64 = Subtarget.isPPC64();
// Get the ABI.
bool isSVR4ABI = Subtarget.isSVR4ABI();
bool isELFv2ABI = Subtarget.isELFv2ABI();
assert((Subtarget.isDarwinABI() || isSVR4ABI) &&
"Currently only Darwin and SVR4 ABIs are supported for PowerPC.");
// Scan the prolog, looking for an UPDATE_VRSAVE instruction. If we find it,
// process it.
if (!isSVR4ABI)
for (unsigned i = 0; MBBI != MBB.end(); ++i, ++MBBI) {
if (MBBI->getOpcode() == PPC::UPDATE_VRSAVE) {
HandleVRSaveUpdate(MBBI, TII);
break;
}
}
// Move MBBI back to the beginning of the prologue block.
MBBI = MBB.begin();
// Work out frame sizes.
unsigned FrameSize = determineFrameLayout(MF);
int NegFrameSize = -FrameSize;
if (!isInt<32>(NegFrameSize))
llvm_unreachable("Unhandled stack size!");
if (MFI->isFrameAddressTaken())
replaceFPWithRealFP(MF);
// Check if the link register (LR) must be saved.
PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
bool MustSaveLR = FI->mustSaveLR();
const SmallVectorImpl<unsigned> &MustSaveCRs = FI->getMustSaveCRs();
// Do we have a frame pointer and/or base pointer for this function?
bool HasFP = hasFP(MF);
bool HasBP = RegInfo->hasBasePointer(MF);
unsigned SPReg = isPPC64 ? PPC::X1 : PPC::R1;
unsigned BPReg = RegInfo->getBaseRegister(MF);
unsigned FPReg = isPPC64 ? PPC::X31 : PPC::R31;
unsigned LRReg = isPPC64 ? PPC::LR8 : PPC::LR;
unsigned ScratchReg = 0;
unsigned TempReg = isPPC64 ? PPC::X12 : PPC::R12; // another scratch reg
// ...(R12/X12 is volatile in both Darwin & SVR4, & can't be a function arg.)
const MCInstrDesc& MFLRInst = TII.get(isPPC64 ? PPC::MFLR8
: PPC::MFLR );
const MCInstrDesc& StoreInst = TII.get(isPPC64 ? PPC::STD
: PPC::STW );
const MCInstrDesc& StoreUpdtInst = TII.get(isPPC64 ? PPC::STDU
: PPC::STWU );
const MCInstrDesc& StoreUpdtIdxInst = TII.get(isPPC64 ? PPC::STDUX
: PPC::STWUX);
const MCInstrDesc& LoadImmShiftedInst = TII.get(isPPC64 ? PPC::LIS8
: PPC::LIS );
const MCInstrDesc& OrImmInst = TII.get(isPPC64 ? PPC::ORI8
: PPC::ORI );
const MCInstrDesc& OrInst = TII.get(isPPC64 ? PPC::OR8
: PPC::OR );
const MCInstrDesc& SubtractCarryingInst = TII.get(isPPC64 ? PPC::SUBFC8
: PPC::SUBFC);
const MCInstrDesc& SubtractImmCarryingInst = TII.get(isPPC64 ? PPC::SUBFIC8
: PPC::SUBFIC);
// Regarding this assert: Even though LR is saved in the caller's frame (i.e.,
// LROffset is positive), that slot is callee-owned. Because PPC32 SVR4 has no
// Red Zone, an asynchronous event (a form of "callee") could claim a frame &
// overwrite it, so PPC32 SVR4 must claim at least a minimal frame to save LR.
assert((isPPC64 || !isSVR4ABI || !(!FrameSize && (MustSaveLR || HasFP))) &&
"FrameSize must be >0 to save/restore the FP or LR for 32-bit SVR4.");
findScratchRegister(&MBB, false, &ScratchReg);
assert(ScratchReg && "No scratch register!");
int LROffset = getReturnSaveOffset();
int FPOffset = 0;
if (HasFP) {
if (isSVR4ABI) {
MachineFrameInfo *FFI = MF.getFrameInfo();
int FPIndex = FI->getFramePointerSaveIndex();
assert(FPIndex && "No Frame Pointer Save Slot!");
FPOffset = FFI->getObjectOffset(FPIndex);
} else {
FPOffset = getFramePointerSaveOffset();
}
}
int BPOffset = 0;
if (HasBP) {
if (isSVR4ABI) {
MachineFrameInfo *FFI = MF.getFrameInfo();
int BPIndex = FI->getBasePointerSaveIndex();
assert(BPIndex && "No Base Pointer Save Slot!");
BPOffset = FFI->getObjectOffset(BPIndex);
} else {
BPOffset = getBasePointerSaveOffset();
}
}
int PBPOffset = 0;
if (FI->usesPICBase()) {
MachineFrameInfo *FFI = MF.getFrameInfo();
int PBPIndex = FI->getPICBasePointerSaveIndex();
assert(PBPIndex && "No PIC Base Pointer Save Slot!");
PBPOffset = FFI->getObjectOffset(PBPIndex);
}
// Get stack alignments.
unsigned MaxAlign = MFI->getMaxAlignment();
if (HasBP && MaxAlign > 1)
assert(isPowerOf2_32(MaxAlign) && isInt<16>(MaxAlign) &&
"Invalid alignment!");
// Frames of 32KB & larger require special handling because they cannot be
// indexed into with a simple STDU/STWU/STD/STW immediate offset operand.
bool isLargeFrame = !isInt<16>(NegFrameSize);
if (MustSaveLR)
BuildMI(MBB, MBBI, dl, MFLRInst, ScratchReg);
assert((isPPC64 || MustSaveCRs.empty()) &&
"Prologue CR saving supported only in 64-bit mode");
if (!MustSaveCRs.empty()) { // will only occur for PPC64
// FIXME: In the ELFv2 ABI, we are not required to save all CR fields.
// If only one or two CR fields are clobbered, it could be more
// efficient to use mfocrf to selectively save just those fields.
MachineInstrBuilder MIB =
BuildMI(MBB, MBBI, dl, TII.get(PPC::MFCR8), TempReg);
for (unsigned i = 0, e = MustSaveCRs.size(); i != e; ++i)
MIB.addReg(MustSaveCRs[i], RegState::ImplicitKill);
}
if (HasFP)
// FIXME: On PPC32 SVR4, we must not spill before claiming the stackframe.
BuildMI(MBB, MBBI, dl, StoreInst)
.addReg(FPReg)
.addImm(FPOffset)
.addReg(SPReg);
if (FI->usesPICBase())
// FIXME: On PPC32 SVR4, we must not spill before claiming the stackframe.
BuildMI(MBB, MBBI, dl, StoreInst)
.addReg(PPC::R30)
.addImm(PBPOffset)
.addReg(SPReg);
if (HasBP)
// FIXME: On PPC32 SVR4, we must not spill before claiming the stackframe.
BuildMI(MBB, MBBI, dl, StoreInst)
.addReg(BPReg)
.addImm(BPOffset)
.addReg(SPReg);
if (MustSaveLR)
// FIXME: On PPC32 SVR4, we must not spill before claiming the stackframe.
BuildMI(MBB, MBBI, dl, StoreInst)
.addReg(ScratchReg)
.addImm(LROffset)
.addReg(SPReg);
if (!MustSaveCRs.empty()) // will only occur for PPC64
BuildMI(MBB, MBBI, dl, TII.get(PPC::STW8))
.addReg(TempReg, getKillRegState(true))
.addImm(8)
.addReg(SPReg);
// Skip the rest if this is a leaf function & all spills fit in the Red Zone.
if (!FrameSize) return;
// Adjust stack pointer: r1 += NegFrameSize.
// If there is a preferred stack alignment, align R1 now
if (HasBP) {
// Save a copy of r1 as the base pointer.
BuildMI(MBB, MBBI, dl, OrInst, BPReg)
.addReg(SPReg)
.addReg(SPReg);
}
if (HasBP && MaxAlign > 1) {
if (isPPC64)
BuildMI(MBB, MBBI, dl, TII.get(PPC::RLDICL), ScratchReg)
.addReg(SPReg)
.addImm(0)
.addImm(64 - Log2_32(MaxAlign));
else // PPC32...
BuildMI(MBB, MBBI, dl, TII.get(PPC::RLWINM), ScratchReg)
.addReg(SPReg)
.addImm(0)
.addImm(32 - Log2_32(MaxAlign))
.addImm(31);
if (!isLargeFrame) {
BuildMI(MBB, MBBI, dl, SubtractImmCarryingInst, ScratchReg)
.addReg(ScratchReg, RegState::Kill)
.addImm(NegFrameSize);
} else {
BuildMI(MBB, MBBI, dl, LoadImmShiftedInst, TempReg)
.addImm(NegFrameSize >> 16);
BuildMI(MBB, MBBI, dl, OrImmInst, TempReg)
.addReg(TempReg, RegState::Kill)
.addImm(NegFrameSize & 0xFFFF);
BuildMI(MBB, MBBI, dl, SubtractCarryingInst, ScratchReg)
.addReg(ScratchReg, RegState::Kill)
.addReg(TempReg, RegState::Kill);
}
BuildMI(MBB, MBBI, dl, StoreUpdtIdxInst, SPReg)
.addReg(SPReg, RegState::Kill)
.addReg(SPReg)
.addReg(ScratchReg);
} else if (!isLargeFrame) {
BuildMI(MBB, MBBI, dl, StoreUpdtInst, SPReg)
.addReg(SPReg)
.addImm(NegFrameSize)
.addReg(SPReg);
} else {
BuildMI(MBB, MBBI, dl, LoadImmShiftedInst, ScratchReg)
.addImm(NegFrameSize >> 16);
BuildMI(MBB, MBBI, dl, OrImmInst, ScratchReg)
.addReg(ScratchReg, RegState::Kill)
.addImm(NegFrameSize & 0xFFFF);
BuildMI(MBB, MBBI, dl, StoreUpdtIdxInst, SPReg)
.addReg(SPReg, RegState::Kill)
.addReg(SPReg)
.addReg(ScratchReg);
}
// Add Call Frame Information for the instructions we generated above.
if (needsCFI) {
unsigned CFIIndex;
if (HasBP) {
// Define CFA in terms of BP. Do this in preference to using FP/SP,
// because if the stack needed aligning then CFA won't be at a fixed
// offset from FP/SP.
unsigned Reg = MRI->getDwarfRegNum(BPReg, true);
CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createDefCfaRegister(nullptr, Reg));
} else {
// Adjust the definition of CFA to account for the change in SP.
assert(NegFrameSize);
CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createDefCfaOffset(nullptr, NegFrameSize));
}
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
if (HasFP) {
// Describe where FP was saved, at a fixed offset from CFA.
unsigned Reg = MRI->getDwarfRegNum(FPReg, true);
CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createOffset(nullptr, Reg, FPOffset));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
}
if (FI->usesPICBase()) {
// Describe where FP was saved, at a fixed offset from CFA.
unsigned Reg = MRI->getDwarfRegNum(PPC::R30, true);
CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createOffset(nullptr, Reg, PBPOffset));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
}
if (HasBP) {
// Describe where BP was saved, at a fixed offset from CFA.
unsigned Reg = MRI->getDwarfRegNum(BPReg, true);
CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createOffset(nullptr, Reg, BPOffset));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
}
if (MustSaveLR) {
// Describe where LR was saved, at a fixed offset from CFA.
unsigned Reg = MRI->getDwarfRegNum(LRReg, true);
CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createOffset(nullptr, Reg, LROffset));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
}
}
// If there is a frame pointer, copy R1 into R31
if (HasFP) {
BuildMI(MBB, MBBI, dl, OrInst, FPReg)
.addReg(SPReg)
.addReg(SPReg);
if (!HasBP && needsCFI) {
// Change the definition of CFA from SP+offset to FP+offset, because SP
// will change at every alloca.
unsigned Reg = MRI->getDwarfRegNum(FPReg, true);
unsigned CFIIndex = MMI.addFrameInst(
MCCFIInstruction::createDefCfaRegister(nullptr, Reg));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
}
}
if (needsCFI) {
// Describe where callee saved registers were saved, at fixed offsets from
// CFA.
const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
for (unsigned I = 0, E = CSI.size(); I != E; ++I) {
unsigned Reg = CSI[I].getReg();
if (Reg == PPC::LR || Reg == PPC::LR8 || Reg == PPC::RM) continue;
// This is a bit of a hack: CR2LT, CR2GT, CR2EQ and CR2UN are just
// subregisters of CR2. We just need to emit a move of CR2.
if (PPC::CRBITRCRegClass.contains(Reg))
continue;
// For SVR4, don't emit a move for the CR spill slot if we haven't
// spilled CRs.
if (isSVR4ABI && (PPC::CR2 <= Reg && Reg <= PPC::CR4)
&& MustSaveCRs.empty())
continue;
// For 64-bit SVR4 when we have spilled CRs, the spill location
// is SP+8, not a frame-relative slot.
if (isSVR4ABI && isPPC64 && (PPC::CR2 <= Reg && Reg <= PPC::CR4)) {
// In the ELFv1 ABI, only CR2 is noted in CFI and stands in for
// the whole CR word. In the ELFv2 ABI, every CR that was
// actually saved gets its own CFI record.
unsigned CRReg = isELFv2ABI? Reg : (unsigned) PPC::CR2;
unsigned CFIIndex = MMI.addFrameInst(MCCFIInstruction::createOffset(
nullptr, MRI->getDwarfRegNum(CRReg, true), 8));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
continue;
}
int Offset = MFI->getObjectOffset(CSI[I].getFrameIdx());
unsigned CFIIndex = MMI.addFrameInst(MCCFIInstruction::createOffset(
nullptr, MRI->getDwarfRegNum(Reg, true), Offset));
BuildMI(MBB, MBBI, dl, TII.get(TargetOpcode::CFI_INSTRUCTION))
.addCFIIndex(CFIIndex);
}
}
}
void PPCFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = MBB.getFirstTerminator();
DebugLoc dl;
if (MBBI != MBB.end())
dl = MBBI->getDebugLoc();
const PPCInstrInfo &TII =
*static_cast<const PPCInstrInfo *>(Subtarget.getInstrInfo());
const PPCRegisterInfo *RegInfo =
static_cast<const PPCRegisterInfo *>(Subtarget.getRegisterInfo());
// Get alignment info so we know how to restore the SP.
const MachineFrameInfo *MFI = MF.getFrameInfo();
// Get the number of bytes allocated from the FrameInfo.
int FrameSize = MFI->getStackSize();
// Get processor type.
bool isPPC64 = Subtarget.isPPC64();
// Get the ABI.
bool isSVR4ABI = Subtarget.isSVR4ABI();
// Check if the link register (LR) has been saved.
PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
bool MustSaveLR = FI->mustSaveLR();
const SmallVectorImpl<unsigned> &MustSaveCRs = FI->getMustSaveCRs();
// Do we have a frame pointer and/or base pointer for this function?
bool HasFP = hasFP(MF);
bool HasBP = RegInfo->hasBasePointer(MF);
unsigned SPReg = isPPC64 ? PPC::X1 : PPC::R1;
unsigned BPReg = RegInfo->getBaseRegister(MF);
unsigned FPReg = isPPC64 ? PPC::X31 : PPC::R31;
unsigned ScratchReg = 0;
unsigned TempReg = isPPC64 ? PPC::X12 : PPC::R12; // another scratch reg
const MCInstrDesc& MTLRInst = TII.get( isPPC64 ? PPC::MTLR8
: PPC::MTLR );
const MCInstrDesc& LoadInst = TII.get( isPPC64 ? PPC::LD
: PPC::LWZ );
const MCInstrDesc& LoadImmShiftedInst = TII.get( isPPC64 ? PPC::LIS8
: PPC::LIS );
const MCInstrDesc& OrImmInst = TII.get( isPPC64 ? PPC::ORI8
: PPC::ORI );
const MCInstrDesc& AddImmInst = TII.get( isPPC64 ? PPC::ADDI8
: PPC::ADDI );
const MCInstrDesc& AddInst = TII.get( isPPC64 ? PPC::ADD8
: PPC::ADD4 );
int LROffset = getReturnSaveOffset();
int FPOffset = 0;
findScratchRegister(&MBB, true, &ScratchReg);
assert(ScratchReg && "No scratch register!");
if (HasFP) {
if (isSVR4ABI) {
MachineFrameInfo *FFI = MF.getFrameInfo();
int FPIndex = FI->getFramePointerSaveIndex();
assert(FPIndex && "No Frame Pointer Save Slot!");
FPOffset = FFI->getObjectOffset(FPIndex);
} else {
FPOffset = getFramePointerSaveOffset();
}
}
int BPOffset = 0;
if (HasBP) {
if (isSVR4ABI) {
MachineFrameInfo *FFI = MF.getFrameInfo();
int BPIndex = FI->getBasePointerSaveIndex();
assert(BPIndex && "No Base Pointer Save Slot!");
BPOffset = FFI->getObjectOffset(BPIndex);
} else {
BPOffset = getBasePointerSaveOffset();
}
}
int PBPOffset = 0;
if (FI->usesPICBase()) {
MachineFrameInfo *FFI = MF.getFrameInfo();
int PBPIndex = FI->getPICBasePointerSaveIndex();
assert(PBPIndex && "No PIC Base Pointer Save Slot!");
PBPOffset = FFI->getObjectOffset(PBPIndex);
}
bool IsReturnBlock = (MBBI != MBB.end() && MBBI->isReturn());
if (IsReturnBlock) {
unsigned RetOpcode = MBBI->getOpcode();
bool UsesTCRet = RetOpcode == PPC::TCRETURNri ||
RetOpcode == PPC::TCRETURNdi ||
RetOpcode == PPC::TCRETURNai ||
RetOpcode == PPC::TCRETURNri8 ||
RetOpcode == PPC::TCRETURNdi8 ||
RetOpcode == PPC::TCRETURNai8;
if (UsesTCRet) {
int MaxTCRetDelta = FI->getTailCallSPDelta();
MachineOperand &StackAdjust = MBBI->getOperand(1);
assert(StackAdjust.isImm() && "Expecting immediate value.");
// Adjust stack pointer.
int StackAdj = StackAdjust.getImm();
int Delta = StackAdj - MaxTCRetDelta;
assert((Delta >= 0) && "Delta must be positive");
if (MaxTCRetDelta>0)
FrameSize += (StackAdj +Delta);
else
FrameSize += StackAdj;
}
}
// Frames of 32KB & larger require special handling because they cannot be
// indexed into with a simple LD/LWZ immediate offset operand.
bool isLargeFrame = !isInt<16>(FrameSize);
if (FrameSize) {
// In the prologue, the loaded (or persistent) stack pointer value is offset
// by the STDU/STDUX/STWU/STWUX instruction. Add this offset back now.
// If this function contained a fastcc call and GuaranteedTailCallOpt is
// enabled (=> hasFastCall()==true) the fastcc call might contain a tail
// call which invalidates the stack pointer value in SP(0). So we use the
// value of R31 in this case.
if (FI->hasFastCall()) {
assert(HasFP && "Expecting a valid frame pointer.");
if (!isLargeFrame) {
BuildMI(MBB, MBBI, dl, AddImmInst, SPReg)
.addReg(FPReg).addImm(FrameSize);
} else {
BuildMI(MBB, MBBI, dl, LoadImmShiftedInst, ScratchReg)
.addImm(FrameSize >> 16);
BuildMI(MBB, MBBI, dl, OrImmInst, ScratchReg)
.addReg(ScratchReg, RegState::Kill)
.addImm(FrameSize & 0xFFFF);
BuildMI(MBB, MBBI, dl, AddInst)
.addReg(SPReg)
.addReg(FPReg)
.addReg(ScratchReg);
}
} else if (!isLargeFrame && !HasBP && !MFI->hasVarSizedObjects()) {
BuildMI(MBB, MBBI, dl, AddImmInst, SPReg)
.addReg(SPReg)
.addImm(FrameSize);
} else {
BuildMI(MBB, MBBI, dl, LoadInst, SPReg)
.addImm(0)
.addReg(SPReg);
}
}
if (MustSaveLR)
BuildMI(MBB, MBBI, dl, LoadInst, ScratchReg)
.addImm(LROffset)
.addReg(SPReg);
assert((isPPC64 || MustSaveCRs.empty()) &&
"Epilogue CR restoring supported only in 64-bit mode");
if (!MustSaveCRs.empty()) // will only occur for PPC64
BuildMI(MBB, MBBI, dl, TII.get(PPC::LWZ8), TempReg)
.addImm(8)
.addReg(SPReg);
if (HasFP)
BuildMI(MBB, MBBI, dl, LoadInst, FPReg)
.addImm(FPOffset)
.addReg(SPReg);
if (FI->usesPICBase())
// FIXME: On PPC32 SVR4, we must not spill before claiming the stackframe.
BuildMI(MBB, MBBI, dl, LoadInst)
.addReg(PPC::R30)
.addImm(PBPOffset)
.addReg(SPReg);
if (HasBP)
BuildMI(MBB, MBBI, dl, LoadInst, BPReg)
.addImm(BPOffset)
.addReg(SPReg);
if (!MustSaveCRs.empty()) // will only occur for PPC64
for (unsigned i = 0, e = MustSaveCRs.size(); i != e; ++i)
BuildMI(MBB, MBBI, dl, TII.get(PPC::MTOCRF8), MustSaveCRs[i])
.addReg(TempReg, getKillRegState(i == e-1));
if (MustSaveLR)
BuildMI(MBB, MBBI, dl, MTLRInst).addReg(ScratchReg);
// Callee pop calling convention. Pop parameter/linkage area. Used for tail
// call optimization
if (IsReturnBlock) {
unsigned RetOpcode = MBBI->getOpcode();
if (MF.getTarget().Options.GuaranteedTailCallOpt &&
(RetOpcode == PPC::BLR || RetOpcode == PPC::BLR8) &&
MF.getFunction()->getCallingConv() == CallingConv::Fast) {
PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
unsigned CallerAllocatedAmt = FI->getMinReservedArea();
if (CallerAllocatedAmt && isInt<16>(CallerAllocatedAmt)) {
BuildMI(MBB, MBBI, dl, AddImmInst, SPReg)
.addReg(SPReg).addImm(CallerAllocatedAmt);
} else {
BuildMI(MBB, MBBI, dl, LoadImmShiftedInst, ScratchReg)
.addImm(CallerAllocatedAmt >> 16);
BuildMI(MBB, MBBI, dl, OrImmInst, ScratchReg)
.addReg(ScratchReg, RegState::Kill)
.addImm(CallerAllocatedAmt & 0xFFFF);
BuildMI(MBB, MBBI, dl, AddInst)
.addReg(SPReg)
.addReg(FPReg)
.addReg(ScratchReg);
}
} else if (RetOpcode == PPC::TCRETURNdi) {
MBBI = MBB.getLastNonDebugInstr();
MachineOperand &JumpTarget = MBBI->getOperand(0);
BuildMI(MBB, MBBI, dl, TII.get(PPC::TAILB)).
addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset());
} else if (RetOpcode == PPC::TCRETURNri) {
MBBI = MBB.getLastNonDebugInstr();
assert(MBBI->getOperand(0).isReg() && "Expecting register operand.");
BuildMI(MBB, MBBI, dl, TII.get(PPC::TAILBCTR));
} else if (RetOpcode == PPC::TCRETURNai) {
MBBI = MBB.getLastNonDebugInstr();
MachineOperand &JumpTarget = MBBI->getOperand(0);
BuildMI(MBB, MBBI, dl, TII.get(PPC::TAILBA)).addImm(JumpTarget.getImm());
} else if (RetOpcode == PPC::TCRETURNdi8) {
MBBI = MBB.getLastNonDebugInstr();
MachineOperand &JumpTarget = MBBI->getOperand(0);
BuildMI(MBB, MBBI, dl, TII.get(PPC::TAILB8)).
addGlobalAddress(JumpTarget.getGlobal(), JumpTarget.getOffset());
} else if (RetOpcode == PPC::TCRETURNri8) {
MBBI = MBB.getLastNonDebugInstr();
assert(MBBI->getOperand(0).isReg() && "Expecting register operand.");
BuildMI(MBB, MBBI, dl, TII.get(PPC::TAILBCTR8));
} else if (RetOpcode == PPC::TCRETURNai8) {
MBBI = MBB.getLastNonDebugInstr();
MachineOperand &JumpTarget = MBBI->getOperand(0);
BuildMI(MBB, MBBI, dl, TII.get(PPC::TAILBA8)).addImm(JumpTarget.getImm());
}
}
}
void PPCFrameLowering::determineCalleeSaves(MachineFunction &MF,
BitVector &SavedRegs,
RegScavenger *RS) const {
TargetFrameLowering::determineCalleeSaves(MF, SavedRegs, RS);
const PPCRegisterInfo *RegInfo =
static_cast<const PPCRegisterInfo *>(Subtarget.getRegisterInfo());
// Save and clear the LR state.
PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
unsigned LR = RegInfo->getRARegister();
FI->setMustSaveLR(MustSaveLR(MF, LR));
SavedRegs.reset(LR);
// Save R31 if necessary
int FPSI = FI->getFramePointerSaveIndex();
bool isPPC64 = Subtarget.isPPC64();
bool isDarwinABI = Subtarget.isDarwinABI();
MachineFrameInfo *MFI = MF.getFrameInfo();
// If the frame pointer save index hasn't been defined yet.
if (!FPSI && needsFP(MF)) {
// Find out what the fix offset of the frame pointer save area.
int FPOffset = getFramePointerSaveOffset();
// Allocate the frame index for frame pointer save area.
FPSI = MFI->CreateFixedObject(isPPC64? 8 : 4, FPOffset, true);
// Save the result.
FI->setFramePointerSaveIndex(FPSI);
}
int BPSI = FI->getBasePointerSaveIndex();
if (!BPSI && RegInfo->hasBasePointer(MF)) {
int BPOffset = getBasePointerSaveOffset();
// Allocate the frame index for the base pointer save area.
BPSI = MFI->CreateFixedObject(isPPC64? 8 : 4, BPOffset, true);
// Save the result.
FI->setBasePointerSaveIndex(BPSI);
}
// Reserve stack space for the PIC Base register (R30).
// Only used in SVR4 32-bit.
if (FI->usesPICBase()) {
int PBPSI = MFI->CreateFixedObject(4, -8, true);
FI->setPICBasePointerSaveIndex(PBPSI);
}
// Reserve stack space to move the linkage area to in case of a tail call.
int TCSPDelta = 0;
if (MF.getTarget().Options.GuaranteedTailCallOpt &&
(TCSPDelta = FI->getTailCallSPDelta()) < 0) {
MFI->CreateFixedObject(-1 * TCSPDelta, TCSPDelta, true);
}
// For 32-bit SVR4, allocate the nonvolatile CR spill slot iff the
// function uses CR 2, 3, or 4.
if (!isPPC64 && !isDarwinABI &&
(SavedRegs.test(PPC::CR2) ||
SavedRegs.test(PPC::CR3) ||
SavedRegs.test(PPC::CR4))) {
int FrameIdx = MFI->CreateFixedObject((uint64_t)4, (int64_t)-4, true);
FI->setCRSpillFrameIndex(FrameIdx);
}
}
void PPCFrameLowering::processFunctionBeforeFrameFinalized(MachineFunction &MF,
RegScavenger *RS) const {
// Early exit if not using the SVR4 ABI.
if (!Subtarget.isSVR4ABI()) {
addScavengingSpillSlot(MF, RS);
return;
}
// Get callee saved register information.
MachineFrameInfo *FFI = MF.getFrameInfo();
const std::vector<CalleeSavedInfo> &CSI = FFI->getCalleeSavedInfo();
// Early exit if no callee saved registers are modified!
if (CSI.empty() && !needsFP(MF)) {
addScavengingSpillSlot(MF, RS);
return;
}
unsigned MinGPR = PPC::R31;
unsigned MinG8R = PPC::X31;
unsigned MinFPR = PPC::F31;
unsigned MinVR = PPC::V31;
bool HasGPSaveArea = false;
bool HasG8SaveArea = false;
bool HasFPSaveArea = false;
bool HasVRSAVESaveArea = false;
bool HasVRSaveArea = false;
SmallVector<CalleeSavedInfo, 18> GPRegs;
SmallVector<CalleeSavedInfo, 18> G8Regs;
SmallVector<CalleeSavedInfo, 18> FPRegs;
SmallVector<CalleeSavedInfo, 18> VRegs;
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
unsigned Reg = CSI[i].getReg();
if (PPC::GPRCRegClass.contains(Reg)) {
HasGPSaveArea = true;
GPRegs.push_back(CSI[i]);
if (Reg < MinGPR) {
MinGPR = Reg;
}
} else if (PPC::G8RCRegClass.contains(Reg)) {
HasG8SaveArea = true;
G8Regs.push_back(CSI[i]);
if (Reg < MinG8R) {
MinG8R = Reg;
}
} else if (PPC::F8RCRegClass.contains(Reg)) {
HasFPSaveArea = true;
FPRegs.push_back(CSI[i]);
if (Reg < MinFPR) {
MinFPR = Reg;
}
} else if (PPC::CRBITRCRegClass.contains(Reg) ||
PPC::CRRCRegClass.contains(Reg)) {
; // do nothing, as we already know whether CRs are spilled
} else if (PPC::VRSAVERCRegClass.contains(Reg)) {
HasVRSAVESaveArea = true;
} else if (PPC::VRRCRegClass.contains(Reg)) {
HasVRSaveArea = true;
VRegs.push_back(CSI[i]);
if (Reg < MinVR) {
MinVR = Reg;
}
} else {
llvm_unreachable("Unknown RegisterClass!");
}
}
PPCFunctionInfo *PFI = MF.getInfo<PPCFunctionInfo>();
const TargetRegisterInfo *TRI = Subtarget.getRegisterInfo();
int64_t LowerBound = 0;
// Take into account stack space reserved for tail calls.
int TCSPDelta = 0;
if (MF.getTarget().Options.GuaranteedTailCallOpt &&
(TCSPDelta = PFI->getTailCallSPDelta()) < 0) {
LowerBound = TCSPDelta;
}
// The Floating-point register save area is right below the back chain word
// of the previous stack frame.
if (HasFPSaveArea) {
for (unsigned i = 0, e = FPRegs.size(); i != e; ++i) {
int FI = FPRegs[i].getFrameIdx();
FFI->setObjectOffset(FI, LowerBound + FFI->getObjectOffset(FI));
}
LowerBound -= (31 - TRI->getEncodingValue(MinFPR) + 1) * 8;
}
// Check whether the frame pointer register is allocated. If so, make sure it
// is spilled to the correct offset.
if (needsFP(MF)) {
HasGPSaveArea = true;
int FI = PFI->getFramePointerSaveIndex();
assert(FI && "No Frame Pointer Save Slot!");
FFI->setObjectOffset(FI, LowerBound + FFI->getObjectOffset(FI));
}
if (PFI->usesPICBase()) {
HasGPSaveArea = true;
int FI = PFI->getPICBasePointerSaveIndex();
assert(FI && "No PIC Base Pointer Save Slot!");
FFI->setObjectOffset(FI, LowerBound + FFI->getObjectOffset(FI));
}
const PPCRegisterInfo *RegInfo =
static_cast<const PPCRegisterInfo *>(Subtarget.getRegisterInfo());
if (RegInfo->hasBasePointer(MF)) {
HasGPSaveArea = true;
int FI = PFI->getBasePointerSaveIndex();
assert(FI && "No Base Pointer Save Slot!");
FFI->setObjectOffset(FI, LowerBound + FFI->getObjectOffset(FI));
}
// General register save area starts right below the Floating-point
// register save area.
if (HasGPSaveArea || HasG8SaveArea) {
// Move general register save area spill slots down, taking into account
// the size of the Floating-point register save area.
for (unsigned i = 0, e = GPRegs.size(); i != e; ++i) {
int FI = GPRegs[i].getFrameIdx();
FFI->setObjectOffset(FI, LowerBound + FFI->getObjectOffset(FI));
}
// Move general register save area spill slots down, taking into account
// the size of the Floating-point register save area.
for (unsigned i = 0, e = G8Regs.size(); i != e; ++i) {
int FI = G8Regs[i].getFrameIdx();
FFI->setObjectOffset(FI, LowerBound + FFI->getObjectOffset(FI));
}
unsigned MinReg =
std::min<unsigned>(TRI->getEncodingValue(MinGPR),
TRI->getEncodingValue(MinG8R));
if (Subtarget.isPPC64()) {
LowerBound -= (31 - MinReg + 1) * 8;
} else {
LowerBound -= (31 - MinReg + 1) * 4;
}
}
// For 32-bit only, the CR save area is below the general register
// save area. For 64-bit SVR4, the CR save area is addressed relative
// to the stack pointer and hence does not need an adjustment here.
// Only CR2 (the first nonvolatile spilled) has an associated frame
// index so that we have a single uniform save area.
if (spillsCR(MF) && !(Subtarget.isPPC64() && Subtarget.isSVR4ABI())) {
// Adjust the frame index of the CR spill slot.
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
unsigned Reg = CSI[i].getReg();
if ((Subtarget.isSVR4ABI() && Reg == PPC::CR2)
// Leave Darwin logic as-is.
|| (!Subtarget.isSVR4ABI() &&
(PPC::CRBITRCRegClass.contains(Reg) ||
PPC::CRRCRegClass.contains(Reg)))) {
int FI = CSI[i].getFrameIdx();
FFI->setObjectOffset(FI, LowerBound + FFI->getObjectOffset(FI));
}
}
LowerBound -= 4; // The CR save area is always 4 bytes long.
}
if (HasVRSAVESaveArea) {
// FIXME SVR4: Is it actually possible to have multiple elements in CSI
// which have the VRSAVE register class?
// Adjust the frame index of the VRSAVE spill slot.
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
unsigned Reg = CSI[i].getReg();
if (PPC::VRSAVERCRegClass.contains(Reg)) {
int FI = CSI[i].getFrameIdx();
FFI->setObjectOffset(FI, LowerBound + FFI->getObjectOffset(FI));
}
}
LowerBound -= 4; // The VRSAVE save area is always 4 bytes long.
}
if (HasVRSaveArea) {
// Insert alignment padding, we need 16-byte alignment.
LowerBound = (LowerBound - 15) & ~(15);
for (unsigned i = 0, e = VRegs.size(); i != e; ++i) {
int FI = VRegs[i].getFrameIdx();
FFI->setObjectOffset(FI, LowerBound + FFI->getObjectOffset(FI));
}
}
addScavengingSpillSlot(MF, RS);
}
void
PPCFrameLowering::addScavengingSpillSlot(MachineFunction &MF,
RegScavenger *RS) const {
// Reserve a slot closest to SP or frame pointer if we have a dynalloc or
// a large stack, which will require scavenging a register to materialize a
// large offset.
// We need to have a scavenger spill slot for spills if the frame size is
// large. In case there is no free register for large-offset addressing,
// this slot is used for the necessary emergency spill. Also, we need the
// slot for dynamic stack allocations.
// The scavenger might be invoked if the frame offset does not fit into
// the 16-bit immediate. We don't know the complete frame size here
// because we've not yet computed callee-saved register spills or the
// needed alignment padding.
unsigned StackSize = determineFrameLayout(MF, false, true);
MachineFrameInfo *MFI = MF.getFrameInfo();
if (MFI->hasVarSizedObjects() || spillsCR(MF) || spillsVRSAVE(MF) ||
hasNonRISpills(MF) || (hasSpills(MF) && !isInt<16>(StackSize))) {
const TargetRegisterClass *GPRC = &PPC::GPRCRegClass;
const TargetRegisterClass *G8RC = &PPC::G8RCRegClass;
const TargetRegisterClass *RC = Subtarget.isPPC64() ? G8RC : GPRC;
RS->addScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
RC->getAlignment(),
false));
// Might we have over-aligned allocas?
bool HasAlVars = MFI->hasVarSizedObjects() &&
MFI->getMaxAlignment() > getStackAlignment();
// These kinds of spills might need two registers.
if (spillsCR(MF) || spillsVRSAVE(MF) || HasAlVars)
RS->addScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
RC->getAlignment(),
false));
}
}
bool
PPCFrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const {
// Currently, this function only handles SVR4 32- and 64-bit ABIs.
// Return false otherwise to maintain pre-existing behavior.
if (!Subtarget.isSVR4ABI())
return false;
MachineFunction *MF = MBB.getParent();
const PPCInstrInfo &TII =
*static_cast<const PPCInstrInfo *>(Subtarget.getInstrInfo());
DebugLoc DL;
bool CRSpilled = false;
MachineInstrBuilder CRMIB;
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
unsigned Reg = CSI[i].getReg();
// Only Darwin actually uses the VRSAVE register, but it can still appear
// here if, for example, @llvm.eh.unwind.init() is used. If we're not on
// Darwin, ignore it.
if (Reg == PPC::VRSAVE && !Subtarget.isDarwinABI())
continue;
// CR2 through CR4 are the nonvolatile CR fields.
bool IsCRField = PPC::CR2 <= Reg && Reg <= PPC::CR4;
// Add the callee-saved register as live-in; it's killed at the spill.
MBB.addLiveIn(Reg);
if (CRSpilled && IsCRField) {
CRMIB.addReg(Reg, RegState::ImplicitKill);
continue;
}
// Insert the spill to the stack frame.
if (IsCRField) {
PPCFunctionInfo *FuncInfo = MF->getInfo<PPCFunctionInfo>();
if (Subtarget.isPPC64()) {
// The actual spill will happen at the start of the prologue.
FuncInfo->addMustSaveCR(Reg);
} else {
CRSpilled = true;
FuncInfo->setSpillsCR();
// 32-bit: FP-relative. Note that we made sure CR2-CR4 all have
// the same frame index in PPCRegisterInfo::hasReservedSpillSlot.
CRMIB = BuildMI(*MF, DL, TII.get(PPC::MFCR), PPC::R12)
.addReg(Reg, RegState::ImplicitKill);
MBB.insert(MI, CRMIB);
MBB.insert(MI, addFrameReference(BuildMI(*MF, DL, TII.get(PPC::STW))
.addReg(PPC::R12,
getKillRegState(true)),
CSI[i].getFrameIdx()));
}
} else {
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
TII.storeRegToStackSlot(MBB, MI, Reg, true,
CSI[i].getFrameIdx(), RC, TRI);
}
}
return true;
}
static void
restoreCRs(bool isPPC64, bool is31,
bool CR2Spilled, bool CR3Spilled, bool CR4Spilled,
MachineBasicBlock &MBB, MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI, unsigned CSIIndex) {
MachineFunction *MF = MBB.getParent();
const PPCInstrInfo &TII = *MF->getSubtarget<PPCSubtarget>().getInstrInfo();
DebugLoc DL;
unsigned RestoreOp, MoveReg;
if (isPPC64)
// This is handled during epilogue generation.
return;
else {
// 32-bit: FP-relative
MBB.insert(MI, addFrameReference(BuildMI(*MF, DL, TII.get(PPC::LWZ),
PPC::R12),
CSI[CSIIndex].getFrameIdx()));
RestoreOp = PPC::MTOCRF;
MoveReg = PPC::R12;
}
if (CR2Spilled)
MBB.insert(MI, BuildMI(*MF, DL, TII.get(RestoreOp), PPC::CR2)
.addReg(MoveReg, getKillRegState(!CR3Spilled && !CR4Spilled)));
if (CR3Spilled)
MBB.insert(MI, BuildMI(*MF, DL, TII.get(RestoreOp), PPC::CR3)
.addReg(MoveReg, getKillRegState(!CR4Spilled)));
if (CR4Spilled)
MBB.insert(MI, BuildMI(*MF, DL, TII.get(RestoreOp), PPC::CR4)
.addReg(MoveReg, getKillRegState(true)));
}
void PPCFrameLowering::
eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
MachineBasicBlock::iterator I) const {
const TargetInstrInfo &TII = *Subtarget.getInstrInfo();
if (MF.getTarget().Options.GuaranteedTailCallOpt &&
I->getOpcode() == PPC::ADJCALLSTACKUP) {
// Add (actually subtract) back the amount the callee popped on return.
if (int CalleeAmt = I->getOperand(1).getImm()) {
bool is64Bit = Subtarget.isPPC64();
CalleeAmt *= -1;
unsigned StackReg = is64Bit ? PPC::X1 : PPC::R1;
unsigned TmpReg = is64Bit ? PPC::X0 : PPC::R0;
unsigned ADDIInstr = is64Bit ? PPC::ADDI8 : PPC::ADDI;
unsigned ADDInstr = is64Bit ? PPC::ADD8 : PPC::ADD4;
unsigned LISInstr = is64Bit ? PPC::LIS8 : PPC::LIS;
unsigned ORIInstr = is64Bit ? PPC::ORI8 : PPC::ORI;
MachineInstr *MI = I;
DebugLoc dl = MI->getDebugLoc();
if (isInt<16>(CalleeAmt)) {
BuildMI(MBB, I, dl, TII.get(ADDIInstr), StackReg)
.addReg(StackReg, RegState::Kill)
.addImm(CalleeAmt);
} else {
MachineBasicBlock::iterator MBBI = I;
BuildMI(MBB, MBBI, dl, TII.get(LISInstr), TmpReg)
.addImm(CalleeAmt >> 16);
BuildMI(MBB, MBBI, dl, TII.get(ORIInstr), TmpReg)
.addReg(TmpReg, RegState::Kill)
.addImm(CalleeAmt & 0xFFFF);
BuildMI(MBB, MBBI, dl, TII.get(ADDInstr), StackReg)
.addReg(StackReg, RegState::Kill)
.addReg(TmpReg);
}
}
}
// Simply discard ADJCALLSTACKDOWN, ADJCALLSTACKUP instructions.
MBB.erase(I);
}
bool
PPCFrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const {
// Currently, this function only handles SVR4 32- and 64-bit ABIs.
// Return false otherwise to maintain pre-existing behavior.
if (!Subtarget.isSVR4ABI())
return false;
MachineFunction *MF = MBB.getParent();
const PPCInstrInfo &TII =
*static_cast<const PPCInstrInfo *>(Subtarget.getInstrInfo());
bool CR2Spilled = false;
bool CR3Spilled = false;
bool CR4Spilled = false;
unsigned CSIIndex = 0;
// Initialize insertion-point logic; we will be restoring in reverse
// order of spill.
MachineBasicBlock::iterator I = MI, BeforeI = I;
bool AtStart = I == MBB.begin();
if (!AtStart)
--BeforeI;
for (unsigned i = 0, e = CSI.size(); i != e; ++i) {
unsigned Reg = CSI[i].getReg();
// Only Darwin actually uses the VRSAVE register, but it can still appear
// here if, for example, @llvm.eh.unwind.init() is used. If we're not on
// Darwin, ignore it.
if (Reg == PPC::VRSAVE && !Subtarget.isDarwinABI())
continue;
if (Reg == PPC::CR2) {
CR2Spilled = true;
// The spill slot is associated only with CR2, which is the
// first nonvolatile spilled. Save it here.
CSIIndex = i;
continue;
} else if (Reg == PPC::CR3) {
CR3Spilled = true;
continue;
} else if (Reg == PPC::CR4) {
CR4Spilled = true;
continue;
} else {
// When we first encounter a non-CR register after seeing at
// least one CR register, restore all spilled CRs together.
if ((CR2Spilled || CR3Spilled || CR4Spilled)
&& !(PPC::CR2 <= Reg && Reg <= PPC::CR4)) {
bool is31 = needsFP(*MF);
restoreCRs(Subtarget.isPPC64(), is31,
CR2Spilled, CR3Spilled, CR4Spilled,
MBB, I, CSI, CSIIndex);
CR2Spilled = CR3Spilled = CR4Spilled = false;
}
// Default behavior for non-CR saves.
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
TII.loadRegFromStackSlot(MBB, I, Reg, CSI[i].getFrameIdx(),
RC, TRI);
assert(I != MBB.begin() &&
"loadRegFromStackSlot didn't insert any code!");
}
// Insert in reverse order.
if (AtStart)
I = MBB.begin();
else {
I = BeforeI;
++I;
}
}
// If we haven't yet spilled the CRs, do so now.
if (CR2Spilled || CR3Spilled || CR4Spilled) {
bool is31 = needsFP(*MF);
restoreCRs(Subtarget.isPPC64(), is31, CR2Spilled, CR3Spilled, CR4Spilled,
MBB, I, CSI, CSIIndex);
}
return true;
}
bool PPCFrameLowering::enableShrinkWrapping(const MachineFunction &MF) const {
return (MF.getSubtarget<PPCSubtarget>().isSVR4ABI() &&
MF.getSubtarget<PPCSubtarget>().isPPC64());
}
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