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llvm/lib/Target/XCore/XCoreFrameLowering.cpp
Evan Cheng 2d28617de2 Move getInitialFrameState from TargetFrameInfo to MCAsmInfo (suggestions for 
better location welcome).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@135438 91177308-0d34-0410-b5e6-96231b3b80d8
2011-07-18 22:29:13 +00:00

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//===-- XCoreFrameLowering.cpp - Frame info for XCore Target -----*- 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 XCore frame information that doesn't fit anywhere else
// cleanly...
//
//===----------------------------------------------------------------------===//
#include "XCore.h"
#include "XCoreFrameLowering.h"
#include "XCoreInstrInfo.h"
#include "XCoreMachineFunctionInfo.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/TargetData.h"
#include "llvm/Target/TargetOptions.h"
#include "llvm/Support/ErrorHandling.h"
using namespace llvm;
// helper functions. FIXME: Eliminate.
static inline bool isImmUs(unsigned val) {
return val <= 11;
}
static inline bool isImmU6(unsigned val) {
return val < (1 << 6);
}
static inline bool isImmU16(unsigned val) {
return val < (1 << 16);
}
static void loadFromStack(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I,
unsigned DstReg, int Offset, DebugLoc dl,
const TargetInstrInfo &TII) {
assert(Offset%4 == 0 && "Misaligned stack offset");
Offset/=4;
bool isU6 = isImmU6(Offset);
if (!isU6 && !isImmU16(Offset))
report_fatal_error("loadFromStack offset too big " + Twine(Offset));
int Opcode = isU6 ? XCore::LDWSP_ru6 : XCore::LDWSP_lru6;
BuildMI(MBB, I, dl, TII.get(Opcode), DstReg)
.addImm(Offset);
}
static void storeToStack(MachineBasicBlock &MBB,
MachineBasicBlock::iterator I,
unsigned SrcReg, int Offset, DebugLoc dl,
const TargetInstrInfo &TII) {
assert(Offset%4 == 0 && "Misaligned stack offset");
Offset/=4;
bool isU6 = isImmU6(Offset);
if (!isU6 && !isImmU16(Offset))
report_fatal_error("storeToStack offset too big " + Twine(Offset));
int Opcode = isU6 ? XCore::STWSP_ru6 : XCore::STWSP_lru6;
BuildMI(MBB, I, dl, TII.get(Opcode))
.addReg(SrcReg)
.addImm(Offset);
}
//===----------------------------------------------------------------------===//
// XCoreFrameLowering:
//===----------------------------------------------------------------------===//
XCoreFrameLowering::XCoreFrameLowering(const XCoreSubtarget &sti)
: TargetFrameLowering(TargetFrameLowering::StackGrowsDown, 4, 0),
STI(sti) {
// Do nothing
}
bool XCoreFrameLowering::hasFP(const MachineFunction &MF) const {
return DisableFramePointerElim(MF) || MF.getFrameInfo()->hasVarSizedObjects();
}
void XCoreFrameLowering::emitPrologue(MachineFunction &MF) const {
MachineBasicBlock &MBB = MF.front(); // Prolog goes in entry BB
MachineBasicBlock::iterator MBBI = MBB.begin();
MachineFrameInfo *MFI = MF.getFrameInfo();
MachineModuleInfo *MMI = &MF.getMMI();
const XCoreRegisterInfo *RegInfo =
static_cast<const XCoreRegisterInfo*>(MF.getTarget().getRegisterInfo());
const XCoreInstrInfo &TII =
*static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
bool FP = hasFP(MF);
bool Nested = MF.getFunction()->getAttributes().hasAttrSomewhere(Attribute::Nest);
if (Nested) {
loadFromStack(MBB, MBBI, XCore::R11, 0, dl, TII);
}
// Work out frame sizes.
int FrameSize = MFI->getStackSize();
assert(FrameSize%4 == 0 && "Misaligned frame size");
FrameSize/=4;
bool isU6 = isImmU6(FrameSize);
if (!isU6 && !isImmU16(FrameSize)) {
// FIXME could emit multiple instructions.
report_fatal_error("emitPrologue Frame size too big: " + Twine(FrameSize));
}
bool emitFrameMoves = RegInfo->needsFrameMoves(MF);
// Do we need to allocate space on the stack?
if (FrameSize) {
bool saveLR = XFI->getUsesLR();
bool LRSavedOnEntry = false;
int Opcode;
if (saveLR && (MFI->getObjectOffset(XFI->getLRSpillSlot()) == 0)) {
Opcode = (isU6) ? XCore::ENTSP_u6 : XCore::ENTSP_lu6;
MBB.addLiveIn(XCore::LR);
saveLR = false;
LRSavedOnEntry = true;
} else {
Opcode = (isU6) ? XCore::EXTSP_u6 : XCore::EXTSP_lu6;
}
BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addImm(FrameSize);
if (emitFrameMoves) {
std::vector<MachineMove> &Moves = MMI->getFrameMoves();
// Show update of SP.
MCSymbol *FrameLabel = MMI->getContext().CreateTempSymbol();
BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(FrameLabel);
MachineLocation SPDst(MachineLocation::VirtualFP);
MachineLocation SPSrc(MachineLocation::VirtualFP, -FrameSize * 4);
Moves.push_back(MachineMove(FrameLabel, SPDst, SPSrc));
if (LRSavedOnEntry) {
MachineLocation CSDst(MachineLocation::VirtualFP, 0);
MachineLocation CSSrc(XCore::LR);
Moves.push_back(MachineMove(FrameLabel, CSDst, CSSrc));
}
}
if (saveLR) {
int LRSpillOffset = MFI->getObjectOffset(XFI->getLRSpillSlot());
storeToStack(MBB, MBBI, XCore::LR, LRSpillOffset + FrameSize*4, dl, TII);
MBB.addLiveIn(XCore::LR);
if (emitFrameMoves) {
MCSymbol *SaveLRLabel = MMI->getContext().CreateTempSymbol();
BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(SaveLRLabel);
MachineLocation CSDst(MachineLocation::VirtualFP, LRSpillOffset);
MachineLocation CSSrc(XCore::LR);
MMI->getFrameMoves().push_back(MachineMove(SaveLRLabel, CSDst, CSSrc));
}
}
}
if (FP) {
// Save R10 to the stack.
int FPSpillOffset = MFI->getObjectOffset(XFI->getFPSpillSlot());
storeToStack(MBB, MBBI, XCore::R10, FPSpillOffset + FrameSize*4, dl, TII);
// R10 is live-in. It is killed at the spill.
MBB.addLiveIn(XCore::R10);
if (emitFrameMoves) {
MCSymbol *SaveR10Label = MMI->getContext().CreateTempSymbol();
BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(SaveR10Label);
MachineLocation CSDst(MachineLocation::VirtualFP, FPSpillOffset);
MachineLocation CSSrc(XCore::R10);
MMI->getFrameMoves().push_back(MachineMove(SaveR10Label, CSDst, CSSrc));
}
// Set the FP from the SP.
unsigned FramePtr = XCore::R10;
BuildMI(MBB, MBBI, dl, TII.get(XCore::LDAWSP_ru6), FramePtr)
.addImm(0);
if (emitFrameMoves) {
// Show FP is now valid.
MCSymbol *FrameLabel = MMI->getContext().CreateTempSymbol();
BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(FrameLabel);
MachineLocation SPDst(FramePtr);
MachineLocation SPSrc(MachineLocation::VirtualFP);
MMI->getFrameMoves().push_back(MachineMove(FrameLabel, SPDst, SPSrc));
}
}
if (emitFrameMoves) {
// Frame moves for callee saved.
std::vector<MachineMove> &Moves = MMI->getFrameMoves();
std::vector<std::pair<MCSymbol*, CalleeSavedInfo> >&SpillLabels =
XFI->getSpillLabels();
for (unsigned I = 0, E = SpillLabels.size(); I != E; ++I) {
MCSymbol *SpillLabel = SpillLabels[I].first;
CalleeSavedInfo &CSI = SpillLabels[I].second;
int Offset = MFI->getObjectOffset(CSI.getFrameIdx());
unsigned Reg = CSI.getReg();
MachineLocation CSDst(MachineLocation::VirtualFP, Offset);
MachineLocation CSSrc(Reg);
Moves.push_back(MachineMove(SpillLabel, CSDst, CSSrc));
}
}
}
void XCoreFrameLowering::emitEpilogue(MachineFunction &MF,
MachineBasicBlock &MBB) const {
MachineFrameInfo *MFI = MF.getFrameInfo();
MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
const XCoreInstrInfo &TII =
*static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
DebugLoc dl = MBBI->getDebugLoc();
bool FP = hasFP(MF);
if (FP) {
// Restore the stack pointer.
unsigned FramePtr = XCore::R10;
BuildMI(MBB, MBBI, dl, TII.get(XCore::SETSP_1r))
.addReg(FramePtr);
}
// Work out frame sizes.
int FrameSize = MFI->getStackSize();
assert(FrameSize%4 == 0 && "Misaligned frame size");
FrameSize/=4;
bool isU6 = isImmU6(FrameSize);
if (!isU6 && !isImmU16(FrameSize)) {
// FIXME could emit multiple instructions.
report_fatal_error("emitEpilogue Frame size too big: " + Twine(FrameSize));
}
if (FrameSize) {
XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
if (FP) {
// Restore R10
int FPSpillOffset = MFI->getObjectOffset(XFI->getFPSpillSlot());
FPSpillOffset += FrameSize*4;
loadFromStack(MBB, MBBI, XCore::R10, FPSpillOffset, dl, TII);
}
bool restoreLR = XFI->getUsesLR();
if (restoreLR && MFI->getObjectOffset(XFI->getLRSpillSlot()) != 0) {
int LRSpillOffset = MFI->getObjectOffset(XFI->getLRSpillSlot());
LRSpillOffset += FrameSize*4;
loadFromStack(MBB, MBBI, XCore::LR, LRSpillOffset, dl, TII);
restoreLR = false;
}
if (restoreLR) {
// Fold prologue into return instruction
assert(MBBI->getOpcode() == XCore::RETSP_u6
|| MBBI->getOpcode() == XCore::RETSP_lu6);
int Opcode = (isU6) ? XCore::RETSP_u6 : XCore::RETSP_lu6;
BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addImm(FrameSize);
MBB.erase(MBBI);
} else {
int Opcode = (isU6) ? XCore::LDAWSP_ru6_RRegs : XCore::LDAWSP_lru6_RRegs;
BuildMI(MBB, MBBI, dl, TII.get(Opcode), XCore::SP).addImm(FrameSize);
}
}
}
bool XCoreFrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const {
if (CSI.empty())
return true;
MachineFunction *MF = MBB.getParent();
const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
XCoreFunctionInfo *XFI = MF->getInfo<XCoreFunctionInfo>();
bool emitFrameMoves = XCoreRegisterInfo::needsFrameMoves(*MF);
DebugLoc DL;
if (MI != MBB.end()) DL = MI->getDebugLoc();
for (std::vector<CalleeSavedInfo>::const_iterator it = CSI.begin();
it != CSI.end(); ++it) {
// Add the callee-saved register as live-in. It's killed at the spill.
MBB.addLiveIn(it->getReg());
unsigned Reg = it->getReg();
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
TII.storeRegToStackSlot(MBB, MI, Reg, true,
it->getFrameIdx(), RC, TRI);
if (emitFrameMoves) {
MCSymbol *SaveLabel = MF->getContext().CreateTempSymbol();
BuildMI(MBB, MI, DL, TII.get(XCore::PROLOG_LABEL)).addSym(SaveLabel);
XFI->getSpillLabels().push_back(std::make_pair(SaveLabel, *it));
}
}
return true;
}
bool XCoreFrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
MachineBasicBlock::iterator MI,
const std::vector<CalleeSavedInfo> &CSI,
const TargetRegisterInfo *TRI) const{
MachineFunction *MF = MBB.getParent();
const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
bool AtStart = MI == MBB.begin();
MachineBasicBlock::iterator BeforeI = MI;
if (!AtStart)
--BeforeI;
for (std::vector<CalleeSavedInfo>::const_iterator it = CSI.begin();
it != CSI.end(); ++it) {
unsigned Reg = it->getReg();
const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
TII.loadRegFromStackSlot(MBB, MI, it->getReg(), it->getFrameIdx(),
RC, TRI);
assert(MI != MBB.begin() &&
"loadRegFromStackSlot didn't insert any code!");
// Insert in reverse order. loadRegFromStackSlot can insert multiple
// instructions.
if (AtStart)
MI = MBB.begin();
else {
MI = BeforeI;
++MI;
}
}
return true;
}
void
XCoreFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
RegScavenger *RS) const {
MachineFrameInfo *MFI = MF.getFrameInfo();
const TargetRegisterInfo *RegInfo = MF.getTarget().getRegisterInfo();
bool LRUsed = MF.getRegInfo().isPhysRegUsed(XCore::LR);
const TargetRegisterClass *RC = XCore::GRRegsRegisterClass;
XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
if (LRUsed) {
MF.getRegInfo().setPhysRegUnused(XCore::LR);
bool isVarArg = MF.getFunction()->isVarArg();
int FrameIdx;
if (! isVarArg) {
// A fixed offset of 0 allows us to save / restore LR using entsp / retsp.
FrameIdx = MFI->CreateFixedObject(RC->getSize(), 0, true);
} else {
FrameIdx = MFI->CreateStackObject(RC->getSize(), RC->getAlignment(),
false);
}
XFI->setUsesLR(FrameIdx);
XFI->setLRSpillSlot(FrameIdx);
}
if (RegInfo->requiresRegisterScavenging(MF)) {
// Reserve a slot close to SP or frame pointer.
RS->setScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
RC->getAlignment(),
false));
}
if (hasFP(MF)) {
// A callee save register is used to hold the FP.
// This needs saving / restoring in the epilogue / prologue.
XFI->setFPSpillSlot(MFI->CreateStackObject(RC->getSize(),
RC->getAlignment(),
false));
}
}
void XCoreFrameLowering::
processFunctionBeforeFrameFinalized(MachineFunction &MF) const {
}
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