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llvm-mirror/lib/Target/PowerPC/PPCFrameLowering.cpp
Evan Cheng 10c6820ff4 Move getInitialFrameState from TargetFrameInfo to MCAsmInfo (suggestions for 
better location welcome).

llvm-svn: 135438
2011-07-18 22:29:13 +00:00

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//=====- PPCFrameLowering.cpp - PPC Frame Information -----------*- C++ -*-===//
//
// 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 "PPCInstrInfo.h"
#include "PPCMachineFunctionInfo.h"
#include "llvm/Function.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/Target/TargetOptions.h"
using namespace llvm;
// FIXME This disables some code that aligns the stack to a boundary bigger than
// the default (16 bytes on Darwin) when there is a stack local of greater
// alignment. This does not currently work, because the delta between old and
// new stack pointers is added to offsets that reference incoming parameters
// after the prolog is generated, and the code that does that doesn't handle a
// variable delta. You don't want to do that anyway; a better approach is to
// reserve another register that retains to the incoming stack pointer, and
// reference parameters relative to that.
#define ALIGN_STACK 0
/// VRRegNo - Map from a numbered VR register to its enum value.
///
static const unsigned short 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
};
/// 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.
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->empty() && I->back().getDesc().isReturn()) {
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();
DebugLoc dl = MI->getDebugLoc();
unsigned UsedRegMask = 0;
for (unsigned i = 0; i != 32; ++i)
if (MF->getRegInfo().isPhysRegUsed(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 = PPCRegisterInfo::getRegisterNumbering(I->first);
if (VRRegNo[RegNo] == I->first) // If this really is a vector reg.
UsedRegMask &= ~(1 << (31-RegNo)); // Doesn't need to be marked.
}
for (MachineRegisterInfo::liveout_iterator
I = MF->getRegInfo().liveout_begin(),
E = MF->getRegInfo().liveout_end(); I != E; ++I) {
unsigned RegNo = PPCRegisterInfo::getRegisterNumbering(*I);
if (VRRegNo[RegNo] == *I) // If this really is a vector reg.
UsedRegMask &= ~(1 << (31-RegNo)); // Doesn't need to be marked.
}
// 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();
}
/// determineFrameLayout - Determine the size of the frame and maximum call
/// frame size.
void PPCFrameLowering::determineFrameLayout(MachineFunction &MF) const {
MachineFrameInfo *MFI = MF.getFrameInfo();
// Get the number of bytes to allocate from the FrameInfo
unsigned FrameSize = MFI->getStackSize();
// Get the alignments provided by the target, and the maximum alignment
// (if any) of the fixed frame objects.
unsigned MaxAlign = MFI->getMaxAlignment();
unsigned TargetAlign = getStackAlignment();
unsigned AlignMask = TargetAlign - 1; //
// 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).
bool DisableRedZone = MF.getFunction()->hasFnAttr(Attribute::NoRedZone);
// FIXME SVR4 The 32-bit SVR4 ABI has no red zone.
if (!DisableRedZone &&
FrameSize <= 224 && // Fits in red zone.
!MFI->hasVarSizedObjects() && // No dynamic alloca.
!MFI->adjustsStack() && // No calls.
(!ALIGN_STACK || MaxAlign <= TargetAlign)) { // No special alignment.
// No need for frame
MFI->setStackSize(0);
return;
}
// 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 and 8 args.
unsigned minCallFrameSize = getMinCallFrameSize(Subtarget.isPPC64(),
Subtarget.isDarwinABI());
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.
MFI->setMaxCallFrameSize(maxCallFrameSize);
// Include call frame size in total.
FrameSize += maxCallFrameSize;
// Make sure the frame is aligned.
FrameSize = (FrameSize + AlignMask) & ~AlignMask;
// Update frame info.
MFI->setStackSize(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()->hasFnAttr(Attribute::Naked))
return false;
return DisableFramePointerElim(MF) || MFI->hasVarSizedObjects() ||
(GuaranteedTailCallOpt && MF.getInfo<PPCFunctionInfo>()->hasFastCall());
}
void PPCFrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
MachineBasicBlock::iterator MBBI = MBB.begin();
MachineFrameInfo *MFI = MF.getFrameInfo();
const PPCInstrInfo &TII =
*static_cast<const PPCInstrInfo*>(MF.getTarget().getInstrInfo());
MachineModuleInfo &MMI = MF.getMMI();
DebugLoc dl;
bool needsFrameMoves = MMI.hasDebugInfo() ||
MF.getFunction()->needsUnwindTableEntry();
// Prepare for frame info.
MCSymbol *FrameLabel = 0;
// Scan the prolog, looking for an UPDATE_VRSAVE instruction. If we find it,
// process it.
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 function.
MBBI = MBB.begin();
// Work out frame sizes.
// FIXME: determineFrameLayout() may change the frame size. This should be
// moved upper, to some hook.
determineFrameLayout(MF);
unsigned FrameSize = MFI->getStackSize();
int NegFrameSize = -FrameSize;
// Get processor type.
bool isPPC64 = Subtarget.isPPC64();
// Get operating system
bool isDarwinABI = Subtarget.isDarwinABI();
// Check if the link register (LR) must be saved.
PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
bool MustSaveLR = FI->mustSaveLR();
// Do we have a frame pointer for this function?
bool HasFP = hasFP(MF);
int LROffset = PPCFrameLowering::getReturnSaveOffset(isPPC64, isDarwinABI);
int FPOffset = 0;
if (HasFP) {
if (Subtarget.isSVR4ABI()) {
MachineFrameInfo *FFI = MF.getFrameInfo();
int FPIndex = FI->getFramePointerSaveIndex();
assert(FPIndex && "No Frame Pointer Save Slot!");
FPOffset = FFI->getObjectOffset(FPIndex);
} else {
FPOffset = PPCFrameLowering::getFramePointerSaveOffset(isPPC64, isDarwinABI);
}
}
if (isPPC64) {
if (MustSaveLR)
BuildMI(MBB, MBBI, dl, TII.get(PPC::MFLR8), PPC::X0);
if (HasFP)
BuildMI(MBB, MBBI, dl, TII.get(PPC::STD))
.addReg(PPC::X31)
.addImm(FPOffset/4)
.addReg(PPC::X1);
if (MustSaveLR)
BuildMI(MBB, MBBI, dl, TII.get(PPC::STD))
.addReg(PPC::X0)
.addImm(LROffset / 4)
.addReg(PPC::X1);
} else {
if (MustSaveLR)
BuildMI(MBB, MBBI, dl, TII.get(PPC::MFLR), PPC::R0);
if (HasFP)
BuildMI(MBB, MBBI, dl, TII.get(PPC::STW))
.addReg(PPC::R31)
.addImm(FPOffset)
.addReg(PPC::R1);
if (MustSaveLR)
BuildMI(MBB, MBBI, dl, TII.get(PPC::STW))
.addReg(PPC::R0)
.addImm(LROffset)
.addReg(PPC::R1);
}
// Skip if a leaf routine.
if (!FrameSize) return;
// Get stack alignments.
unsigned TargetAlign = getStackAlignment();
unsigned MaxAlign = MFI->getMaxAlignment();
// Adjust stack pointer: r1 += NegFrameSize.
// If there is a preferred stack alignment, align R1 now
if (!isPPC64) {
// PPC32.
if (ALIGN_STACK && MaxAlign > TargetAlign) {
assert(isPowerOf2_32(MaxAlign) && isInt<16>(MaxAlign) &&
"Invalid alignment!");
assert(isInt<16>(NegFrameSize) && "Unhandled stack size and alignment!");
BuildMI(MBB, MBBI, dl, TII.get(PPC::RLWINM), PPC::R0)
.addReg(PPC::R1)
.addImm(0)
.addImm(32 - Log2_32(MaxAlign))
.addImm(31);
BuildMI(MBB, MBBI, dl, TII.get(PPC::SUBFIC) ,PPC::R0)
.addReg(PPC::R0, RegState::Kill)
.addImm(NegFrameSize);
BuildMI(MBB, MBBI, dl, TII.get(PPC::STWUX))
.addReg(PPC::R1)
.addReg(PPC::R1)
.addReg(PPC::R0);
} else if (isInt<16>(NegFrameSize)) {
BuildMI(MBB, MBBI, dl, TII.get(PPC::STWU), PPC::R1)
.addReg(PPC::R1)
.addImm(NegFrameSize)
.addReg(PPC::R1);
} else {
BuildMI(MBB, MBBI, dl, TII.get(PPC::LIS), PPC::R0)
.addImm(NegFrameSize >> 16);
BuildMI(MBB, MBBI, dl, TII.get(PPC::ORI), PPC::R0)
.addReg(PPC::R0, RegState::Kill)
.addImm(NegFrameSize & 0xFFFF);
BuildMI(MBB, MBBI, dl, TII.get(PPC::STWUX))
.addReg(PPC::R1)
.addReg(PPC::R1)
.addReg(PPC::R0);
}
} else { // PPC64.
if (ALIGN_STACK && MaxAlign > TargetAlign) {
assert(isPowerOf2_32(MaxAlign) && isInt<16>(MaxAlign) &&
"Invalid alignment!");
assert(isInt<16>(NegFrameSize) && "Unhandled stack size and alignment!");
BuildMI(MBB, MBBI, dl, TII.get(PPC::RLDICL), PPC::X0)
.addReg(PPC::X1)
.addImm(0)
.addImm(64 - Log2_32(MaxAlign));
BuildMI(MBB, MBBI, dl, TII.get(PPC::SUBFIC8), PPC::X0)
.addReg(PPC::X0)
.addImm(NegFrameSize);
BuildMI(MBB, MBBI, dl, TII.get(PPC::STDUX))
.addReg(PPC::X1)
.addReg(PPC::X1)
.addReg(PPC::X0);
} else if (isInt<16>(NegFrameSize)) {
BuildMI(MBB, MBBI, dl, TII.get(PPC::STDU), PPC::X1)
.addReg(PPC::X1)
.addImm(NegFrameSize / 4)
.addReg(PPC::X1);
} else {
BuildMI(MBB, MBBI, dl, TII.get(PPC::LIS8), PPC::X0)
.addImm(NegFrameSize >> 16);
BuildMI(MBB, MBBI, dl, TII.get(PPC::ORI8), PPC::X0)
.addReg(PPC::X0, RegState::Kill)
.addImm(NegFrameSize & 0xFFFF);
BuildMI(MBB, MBBI, dl, TII.get(PPC::STDUX))
.addReg(PPC::X1)
.addReg(PPC::X1)
.addReg(PPC::X0);
}
}
std::vector<MachineMove> &Moves = MMI.getFrameMoves();
// Add the "machine moves" for the instructions we generated above, but in
// reverse order.
if (needsFrameMoves) {
// Mark effective beginning of when frame pointer becomes valid.
FrameLabel = MMI.getContext().CreateTempSymbol();
BuildMI(MBB, MBBI, dl, TII.get(PPC::PROLOG_LABEL)).addSym(FrameLabel);
// Show update of SP.
if (NegFrameSize) {
MachineLocation SPDst(MachineLocation::VirtualFP);
MachineLocation SPSrc(MachineLocation::VirtualFP, NegFrameSize);
Moves.push_back(MachineMove(FrameLabel, SPDst, SPSrc));
} else {
MachineLocation SP(isPPC64 ? PPC::X31 : PPC::R31);
Moves.push_back(MachineMove(FrameLabel, SP, SP));
}
if (HasFP) {
MachineLocation FPDst(MachineLocation::VirtualFP, FPOffset);
MachineLocation FPSrc(isPPC64 ? PPC::X31 : PPC::R31);
Moves.push_back(MachineMove(FrameLabel, FPDst, FPSrc));
}
if (MustSaveLR) {
MachineLocation LRDst(MachineLocation::VirtualFP, LROffset);
MachineLocation LRSrc(isPPC64 ? PPC::LR8 : PPC::LR);
Moves.push_back(MachineMove(FrameLabel, LRDst, LRSrc));
}
}
MCSymbol *ReadyLabel = 0;
// If there is a frame pointer, copy R1 into R31
if (HasFP) {
if (!isPPC64) {
BuildMI(MBB, MBBI, dl, TII.get(PPC::OR), PPC::R31)
.addReg(PPC::R1)
.addReg(PPC::R1);
} else {
BuildMI(MBB, MBBI, dl, TII.get(PPC::OR8), PPC::X31)
.addReg(PPC::X1)
.addReg(PPC::X1);
}
if (needsFrameMoves) {
ReadyLabel = MMI.getContext().CreateTempSymbol();
// Mark effective beginning of when frame pointer is ready.
BuildMI(MBB, MBBI, dl, TII.get(PPC::PROLOG_LABEL)).addSym(ReadyLabel);
MachineLocation FPDst(HasFP ? (isPPC64 ? PPC::X31 : PPC::R31) :
(isPPC64 ? PPC::X1 : PPC::R1));
MachineLocation FPSrc(MachineLocation::VirtualFP);
Moves.push_back(MachineMove(ReadyLabel, FPDst, FPSrc));
}
}
if (needsFrameMoves) {
MCSymbol *Label = HasFP ? ReadyLabel : FrameLabel;
// Add callee saved registers to move list.
const std::vector<CalleeSavedInfo> &CSI = MFI->getCalleeSavedInfo();
for (unsigned I = 0, E = CSI.size(); I != E; ++I) {
int Offset = MFI->getObjectOffset(CSI[I].getFrameIdx());
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 (Reg == PPC::CR2LT || Reg == PPC::CR2GT || Reg == PPC::CR2EQ)
continue;
if (Reg == PPC::CR2UN)
Reg = PPC::CR2;
MachineLocation CSDst(MachineLocation::VirtualFP, Offset);
MachineLocation CSSrc(Reg);
Moves.push_back(MachineMove(Label, CSDst, CSSrc));
}
}
}
void PPCFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
assert(MBBI != MBB.end() && "Returning block has no terminator");
const PPCInstrInfo &TII =
*static_cast<const PPCInstrInfo*>(MF.getTarget().getInstrInfo());
unsigned RetOpcode = MBBI->getOpcode();
DebugLoc dl;
assert((RetOpcode == PPC::BLR ||
RetOpcode == PPC::TCRETURNri ||
RetOpcode == PPC::TCRETURNdi ||
RetOpcode == PPC::TCRETURNai ||
RetOpcode == PPC::TCRETURNri8 ||
RetOpcode == PPC::TCRETURNdi8 ||
RetOpcode == PPC::TCRETURNai8) &&
"Can only insert epilog into returning blocks");
// Get alignment info so we know how to restore r1
const MachineFrameInfo *MFI = MF.getFrameInfo();
unsigned TargetAlign = getStackAlignment();
unsigned MaxAlign = MFI->getMaxAlignment();
// Get the number of bytes allocated from the FrameInfo.
int FrameSize = MFI->getStackSize();
// Get processor type.
bool isPPC64 = Subtarget.isPPC64();
// Get operating system
bool isDarwinABI = Subtarget.isDarwinABI();
// Check if the link register (LR) has been saved.
PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
bool MustSaveLR = FI->mustSaveLR();
// Do we have a frame pointer for this function?
bool HasFP = hasFP(MF);
int LROffset = PPCFrameLowering::getReturnSaveOffset(isPPC64, isDarwinABI);
int FPOffset = 0;
if (HasFP) {
if (Subtarget.isSVR4ABI()) {
MachineFrameInfo *FFI = MF.getFrameInfo();
int FPIndex = FI->getFramePointerSaveIndex();
assert(FPIndex && "No Frame Pointer Save Slot!");
FPOffset = FFI->getObjectOffset(FPIndex);
} else {
FPOffset = PPCFrameLowering::getFramePointerSaveOffset(isPPC64, isDarwinABI);
}
}
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;
}
if (FrameSize) {
// The loaded (or persistent) stack pointer value is offset by the 'stwu'
// on entry to the function. Add this offset back now.
if (!isPPC64) {
// 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() && isInt<16>(FrameSize)) {
assert(hasFP(MF) && "Expecting a valid the frame pointer.");
BuildMI(MBB, MBBI, dl, TII.get(PPC::ADDI), PPC::R1)
.addReg(PPC::R31).addImm(FrameSize);
} else if(FI->hasFastCall()) {
BuildMI(MBB, MBBI, dl, TII.get(PPC::LIS), PPC::R0)
.addImm(FrameSize >> 16);
BuildMI(MBB, MBBI, dl, TII.get(PPC::ORI), PPC::R0)
.addReg(PPC::R0, RegState::Kill)
.addImm(FrameSize & 0xFFFF);
BuildMI(MBB, MBBI, dl, TII.get(PPC::ADD4))
.addReg(PPC::R1)
.addReg(PPC::R31)
.addReg(PPC::R0);
} else if (isInt<16>(FrameSize) &&
(!ALIGN_STACK || TargetAlign >= MaxAlign) &&
!MFI->hasVarSizedObjects()) {
BuildMI(MBB, MBBI, dl, TII.get(PPC::ADDI), PPC::R1)
.addReg(PPC::R1).addImm(FrameSize);
} else {
BuildMI(MBB, MBBI, dl, TII.get(PPC::LWZ),PPC::R1)
.addImm(0).addReg(PPC::R1);
}
} else {
if (FI->hasFastCall() && isInt<16>(FrameSize)) {
assert(hasFP(MF) && "Expecting a valid the frame pointer.");
BuildMI(MBB, MBBI, dl, TII.get(PPC::ADDI8), PPC::X1)
.addReg(PPC::X31).addImm(FrameSize);
} else if(FI->hasFastCall()) {
BuildMI(MBB, MBBI, dl, TII.get(PPC::LIS8), PPC::X0)
.addImm(FrameSize >> 16);
BuildMI(MBB, MBBI, dl, TII.get(PPC::ORI8), PPC::X0)
.addReg(PPC::X0, RegState::Kill)
.addImm(FrameSize & 0xFFFF);
BuildMI(MBB, MBBI, dl, TII.get(PPC::ADD8))
.addReg(PPC::X1)
.addReg(PPC::X31)
.addReg(PPC::X0);
} else if (isInt<16>(FrameSize) && TargetAlign >= MaxAlign &&
!MFI->hasVarSizedObjects()) {
BuildMI(MBB, MBBI, dl, TII.get(PPC::ADDI8), PPC::X1)
.addReg(PPC::X1).addImm(FrameSize);
} else {
BuildMI(MBB, MBBI, dl, TII.get(PPC::LD), PPC::X1)
.addImm(0).addReg(PPC::X1);
}
}
}
if (isPPC64) {
if (MustSaveLR)
BuildMI(MBB, MBBI, dl, TII.get(PPC::LD), PPC::X0)
.addImm(LROffset/4).addReg(PPC::X1);
if (HasFP)
BuildMI(MBB, MBBI, dl, TII.get(PPC::LD), PPC::X31)
.addImm(FPOffset/4).addReg(PPC::X1);
if (MustSaveLR)
BuildMI(MBB, MBBI, dl, TII.get(PPC::MTLR8)).addReg(PPC::X0);
} else {
if (MustSaveLR)
BuildMI(MBB, MBBI, dl, TII.get(PPC::LWZ), PPC::R0)
.addImm(LROffset).addReg(PPC::R1);
if (HasFP)
BuildMI(MBB, MBBI, dl, TII.get(PPC::LWZ), PPC::R31)
.addImm(FPOffset).addReg(PPC::R1);
if (MustSaveLR)
BuildMI(MBB, MBBI, dl, TII.get(PPC::MTLR)).addReg(PPC::R0);
}
// Callee pop calling convention. Pop parameter/linkage area. Used for tail
// call optimization
if (GuaranteedTailCallOpt && RetOpcode == PPC::BLR &&
MF.getFunction()->getCallingConv() == CallingConv::Fast) {
PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
unsigned CallerAllocatedAmt = FI->getMinReservedArea();
unsigned StackReg = isPPC64 ? PPC::X1 : PPC::R1;
unsigned FPReg = isPPC64 ? PPC::X31 : PPC::R31;
unsigned TmpReg = isPPC64 ? PPC::X0 : PPC::R0;
unsigned ADDIInstr = isPPC64 ? PPC::ADDI8 : PPC::ADDI;
unsigned ADDInstr = isPPC64 ? PPC::ADD8 : PPC::ADD4;
unsigned LISInstr = isPPC64 ? PPC::LIS8 : PPC::LIS;
unsigned ORIInstr = isPPC64 ? PPC::ORI8 : PPC::ORI;
if (CallerAllocatedAmt && isInt<16>(CallerAllocatedAmt)) {
BuildMI(MBB, MBBI, dl, TII.get(ADDIInstr), StackReg)
.addReg(StackReg).addImm(CallerAllocatedAmt);
} else {
BuildMI(MBB, MBBI, dl, TII.get(LISInstr), TmpReg)
.addImm(CallerAllocatedAmt >> 16);
BuildMI(MBB, MBBI, dl, TII.get(ORIInstr), TmpReg)
.addReg(TmpReg, RegState::Kill)
.addImm(CallerAllocatedAmt & 0xFFFF);
BuildMI(MBB, MBBI, dl, TII.get(ADDInstr))
.addReg(StackReg)
.addReg(FPReg)
.addReg(TmpReg);
}
} 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());
}
}
static bool spillsCR(const MachineFunction &MF) {
const PPCFunctionInfo *FuncInfo = MF.getInfo<PPCFunctionInfo>();
return FuncInfo->isCRSpilled();
}
/// 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();
}
void
PPCFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
RegScavenger *RS) const {
const TargetRegisterInfo *RegInfo = MF.getTarget().getRegisterInfo();
// Save and clear the LR state.
PPCFunctionInfo *FI = MF.getInfo<PPCFunctionInfo>();
unsigned LR = RegInfo->getRARegister();
FI->setMustSaveLR(MustSaveLR(MF, LR));
MF.getRegInfo().setPhysRegUnused(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(isPPC64, isDarwinABI);
// Allocate the frame index for frame pointer save area.
FPSI = MFI->CreateFixedObject(isPPC64? 8 : 4, FPOffset, true);
// Save the result.
FI->setFramePointerSaveIndex(FPSI);
}
// Reserve stack space to move the linkage area to in case of a tail call.
int TCSPDelta = 0;
if (GuaranteedTailCallOpt && (TCSPDelta = FI->getTailCallSPDelta()) < 0) {
MFI->CreateFixedObject(-1 * TCSPDelta, TCSPDelta, true);
}
// 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.
// FIXME: this doesn't actually check stack size, so is a bit pessimistic
// FIXME: doesn't detect whether or not we need to spill vXX, which requires
// r0 for now.
if (RegInfo->requiresRegisterScavenging(MF)) // FIXME (64-bit): Enable.
if (needsFP(MF) || spillsCR(MF)) {
const TargetRegisterClass *GPRC = &PPC::GPRCRegClass;
const TargetRegisterClass *G8RC = &PPC::G8RCRegClass;
const TargetRegisterClass *RC = isPPC64 ? G8RC : GPRC;
RS->setScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
RC->getAlignment(),
false));
}
}
void PPCFrameLowering::processFunctionBeforeFrameFinalized(MachineFunction &MF)
const {
// Early exit if not using the SVR4 ABI.
if (!Subtarget.isSVR4ABI())
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)) {
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 HasCRSaveArea = 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::GPRCRegisterClass->contains(Reg)) {
HasGPSaveArea = true;
GPRegs.push_back(CSI[i]);
if (Reg < MinGPR) {
MinGPR = Reg;
}
} else if (PPC::G8RCRegisterClass->contains(Reg)) {
HasG8SaveArea = true;
G8Regs.push_back(CSI[i]);
if (Reg < MinG8R) {
MinG8R = Reg;
}
} else if (PPC::F8RCRegisterClass->contains(Reg)) {
HasFPSaveArea = true;
FPRegs.push_back(CSI[i]);
if (Reg < MinFPR) {
MinFPR = Reg;
}
// FIXME SVR4: Disable CR save area for now.
} else if (PPC::CRBITRCRegisterClass->contains(Reg)
|| PPC::CRRCRegisterClass->contains(Reg)) {
// HasCRSaveArea = true;
} else if (PPC::VRSAVERCRegisterClass->contains(Reg)) {
HasVRSAVESaveArea = true;
} else if (PPC::VRRCRegisterClass->contains(Reg)) {
HasVRSaveArea = true;
VRegs.push_back(CSI[i]);
if (Reg < MinVR) {
MinVR = Reg;
}
} else {
llvm_unreachable("Unknown RegisterClass!");
}
}
PPCFunctionInfo *PFI = MF.getInfo<PPCFunctionInfo>();
int64_t LowerBound = 0;
// Take into account stack space reserved for tail calls.
int TCSPDelta = 0;
if (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 - PPCRegisterInfo::getRegisterNumbering(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));
}
// 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>(PPCRegisterInfo::getRegisterNumbering(MinGPR),
PPCRegisterInfo::getRegisterNumbering(MinG8R));
if (Subtarget.isPPC64()) {
LowerBound -= (31 - MinReg + 1) * 8;
} else {
LowerBound -= (31 - MinReg + 1) * 4;
}
}
// The CR save area is below the general register save area.
if (HasCRSaveArea) {
// FIXME SVR4: Is it actually possible to have multiple elements in CSI
// which have the CR/CRBIT register class?
// 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 (PPC::CRBITRCRegisterClass->contains(Reg) ||
PPC::CRRCRegisterClass->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::VRSAVERCRegisterClass->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));
}
}
}
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