XCoreFrameLowering.cpp revision 420761a0f193e87d08ee1c51b26bba23ab4bac7f 
1//===-- XCoreFrameLowering.cpp - Frame info for XCore Target --------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file contains XCore frame information that doesn't fit anywhere else
11// cleanly...
12//
13//===----------------------------------------------------------------------===//
14
15#include "XCoreFrameLowering.h"
16#include "XCore.h"
17#include "XCoreInstrInfo.h"
18#include "XCoreMachineFunctionInfo.h"
19#include "llvm/Function.h"
20#include "llvm/CodeGen/MachineFrameInfo.h"
21#include "llvm/CodeGen/MachineFunction.h"
22#include "llvm/CodeGen/MachineInstrBuilder.h"
23#include "llvm/CodeGen/MachineModuleInfo.h"
24#include "llvm/CodeGen/MachineRegisterInfo.h"
25#include "llvm/CodeGen/RegisterScavenging.h"
26#include "llvm/Target/TargetData.h"
27#include "llvm/Target/TargetOptions.h"
28#include "llvm/Support/ErrorHandling.h"
29
30using namespace llvm;
31
32// helper functions. FIXME: Eliminate.
33static inline bool isImmUs(unsigned val) {
34  return val <= 11;
35}
36
37static inline bool isImmU6(unsigned val) {
38  return val < (1 << 6);
39}
40
41static inline bool isImmU16(unsigned val) {
42  return val < (1 << 16);
43}
44
45static void loadFromStack(MachineBasicBlock &MBB,
46                          MachineBasicBlock::iterator I,
47                          unsigned DstReg, int Offset, DebugLoc dl,
48                          const TargetInstrInfo &TII) {
49  assert(Offset%4 == 0 && "Misaligned stack offset");
50  Offset/=4;
51  bool isU6 = isImmU6(Offset);
52  if (!isU6 && !isImmU16(Offset))
53    report_fatal_error("loadFromStack offset too big " + Twine(Offset));
54  int Opcode = isU6 ? XCore::LDWSP_ru6 : XCore::LDWSP_lru6;
55  BuildMI(MBB, I, dl, TII.get(Opcode), DstReg)
56    .addImm(Offset);
57}
58
59
60static void storeToStack(MachineBasicBlock &MBB,
61                         MachineBasicBlock::iterator I,
62                         unsigned SrcReg, int Offset, DebugLoc dl,
63                         const TargetInstrInfo &TII) {
64  assert(Offset%4 == 0 && "Misaligned stack offset");
65  Offset/=4;
66  bool isU6 = isImmU6(Offset);
67  if (!isU6 && !isImmU16(Offset))
68    report_fatal_error("storeToStack offset too big " + Twine(Offset));
69  int Opcode = isU6 ? XCore::STWSP_ru6 : XCore::STWSP_lru6;
70  BuildMI(MBB, I, dl, TII.get(Opcode))
71    .addReg(SrcReg)
72    .addImm(Offset);
73}
74
75
76//===----------------------------------------------------------------------===//
77// XCoreFrameLowering:
78//===----------------------------------------------------------------------===//
79
80XCoreFrameLowering::XCoreFrameLowering(const XCoreSubtarget &sti)
81  : TargetFrameLowering(TargetFrameLowering::StackGrowsDown, 4, 0),
82    STI(sti) {
83  // Do nothing
84}
85
86bool XCoreFrameLowering::hasFP(const MachineFunction &MF) const {
87  return MF.getTarget().Options.DisableFramePointerElim(MF) ||
88    MF.getFrameInfo()->hasVarSizedObjects();
89}
90
91void XCoreFrameLowering::emitPrologue(MachineFunction &MF) const {
92  MachineBasicBlock &MBB = MF.front();   // Prolog goes in entry BB
93  MachineBasicBlock::iterator MBBI = MBB.begin();
94  MachineFrameInfo *MFI = MF.getFrameInfo();
95  MachineModuleInfo *MMI = &MF.getMMI();
96  const XCoreInstrInfo &TII =
97    *static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
98  XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
99  DebugLoc dl = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();
100
101  bool FP = hasFP(MF);
102  bool Nested = MF.getFunction()->
103                getAttributes().hasAttrSomewhere(Attribute::Nest);
104
105  if (Nested) {
106    loadFromStack(MBB, MBBI, XCore::R11, 0, dl, TII);
107  }
108
109  // Work out frame sizes.
110  int FrameSize = MFI->getStackSize();
111  assert(FrameSize%4 == 0 && "Misaligned frame size");
112  FrameSize/=4;
113
114  bool isU6 = isImmU6(FrameSize);
115
116  if (!isU6 && !isImmU16(FrameSize)) {
117    // FIXME could emit multiple instructions.
118    report_fatal_error("emitPrologue Frame size too big: " + Twine(FrameSize));
119  }
120  bool emitFrameMoves = XCoreRegisterInfo::needsFrameMoves(MF);
121
122  // Do we need to allocate space on the stack?
123  if (FrameSize) {
124    bool saveLR = XFI->getUsesLR();
125    bool LRSavedOnEntry = false;
126    int Opcode;
127    if (saveLR && (MFI->getObjectOffset(XFI->getLRSpillSlot()) == 0)) {
128      Opcode = (isU6) ? XCore::ENTSP_u6 : XCore::ENTSP_lu6;
129      MBB.addLiveIn(XCore::LR);
130      saveLR = false;
131      LRSavedOnEntry = true;
132    } else {
133      Opcode = (isU6) ? XCore::EXTSP_u6 : XCore::EXTSP_lu6;
134    }
135    BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addImm(FrameSize);
136
137    if (emitFrameMoves) {
138      std::vector<MachineMove> &Moves = MMI->getFrameMoves();
139
140      // Show update of SP.
141      MCSymbol *FrameLabel = MMI->getContext().CreateTempSymbol();
142      BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(FrameLabel);
143
144      MachineLocation SPDst(MachineLocation::VirtualFP);
145      MachineLocation SPSrc(MachineLocation::VirtualFP, -FrameSize * 4);
146      Moves.push_back(MachineMove(FrameLabel, SPDst, SPSrc));
147
148      if (LRSavedOnEntry) {
149        MachineLocation CSDst(MachineLocation::VirtualFP, 0);
150        MachineLocation CSSrc(XCore::LR);
151        Moves.push_back(MachineMove(FrameLabel, CSDst, CSSrc));
152      }
153    }
154    if (saveLR) {
155      int LRSpillOffset = MFI->getObjectOffset(XFI->getLRSpillSlot());
156      storeToStack(MBB, MBBI, XCore::LR, LRSpillOffset + FrameSize*4, dl, TII);
157      MBB.addLiveIn(XCore::LR);
158
159      if (emitFrameMoves) {
160        MCSymbol *SaveLRLabel = MMI->getContext().CreateTempSymbol();
161        BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(SaveLRLabel);
162        MachineLocation CSDst(MachineLocation::VirtualFP, LRSpillOffset);
163        MachineLocation CSSrc(XCore::LR);
164        MMI->getFrameMoves().push_back(MachineMove(SaveLRLabel, CSDst, CSSrc));
165      }
166    }
167  }
168
169  if (FP) {
170    // Save R10 to the stack.
171    int FPSpillOffset = MFI->getObjectOffset(XFI->getFPSpillSlot());
172    storeToStack(MBB, MBBI, XCore::R10, FPSpillOffset + FrameSize*4, dl, TII);
173    // R10 is live-in. It is killed at the spill.
174    MBB.addLiveIn(XCore::R10);
175    if (emitFrameMoves) {
176      MCSymbol *SaveR10Label = MMI->getContext().CreateTempSymbol();
177      BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(SaveR10Label);
178      MachineLocation CSDst(MachineLocation::VirtualFP, FPSpillOffset);
179      MachineLocation CSSrc(XCore::R10);
180      MMI->getFrameMoves().push_back(MachineMove(SaveR10Label, CSDst, CSSrc));
181    }
182    // Set the FP from the SP.
183    unsigned FramePtr = XCore::R10;
184    BuildMI(MBB, MBBI, dl, TII.get(XCore::LDAWSP_ru6), FramePtr)
185      .addImm(0);
186    if (emitFrameMoves) {
187      // Show FP is now valid.
188      MCSymbol *FrameLabel = MMI->getContext().CreateTempSymbol();
189      BuildMI(MBB, MBBI, dl, TII.get(XCore::PROLOG_LABEL)).addSym(FrameLabel);
190      MachineLocation SPDst(FramePtr);
191      MachineLocation SPSrc(MachineLocation::VirtualFP);
192      MMI->getFrameMoves().push_back(MachineMove(FrameLabel, SPDst, SPSrc));
193    }
194  }
195
196  if (emitFrameMoves) {
197    // Frame moves for callee saved.
198    std::vector<MachineMove> &Moves = MMI->getFrameMoves();
199    std::vector<std::pair<MCSymbol*, CalleeSavedInfo> >&SpillLabels =
200        XFI->getSpillLabels();
201    for (unsigned I = 0, E = SpillLabels.size(); I != E; ++I) {
202      MCSymbol *SpillLabel = SpillLabels[I].first;
203      CalleeSavedInfo &CSI = SpillLabels[I].second;
204      int Offset = MFI->getObjectOffset(CSI.getFrameIdx());
205      unsigned Reg = CSI.getReg();
206      MachineLocation CSDst(MachineLocation::VirtualFP, Offset);
207      MachineLocation CSSrc(Reg);
208      Moves.push_back(MachineMove(SpillLabel, CSDst, CSSrc));
209    }
210  }
211}
212
213void XCoreFrameLowering::emitEpilogue(MachineFunction &MF,
214                                     MachineBasicBlock &MBB) const {
215  MachineFrameInfo *MFI            = MF.getFrameInfo();
216  MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
217  const XCoreInstrInfo &TII =
218    *static_cast<const XCoreInstrInfo*>(MF.getTarget().getInstrInfo());
219  DebugLoc dl = MBBI->getDebugLoc();
220
221  bool FP = hasFP(MF);
222  if (FP) {
223    // Restore the stack pointer.
224    unsigned FramePtr = XCore::R10;
225    BuildMI(MBB, MBBI, dl, TII.get(XCore::SETSP_1r))
226      .addReg(FramePtr);
227  }
228
229  // Work out frame sizes.
230  int FrameSize = MFI->getStackSize();
231
232  assert(FrameSize%4 == 0 && "Misaligned frame size");
233
234  FrameSize/=4;
235
236  bool isU6 = isImmU6(FrameSize);
237
238  if (!isU6 && !isImmU16(FrameSize)) {
239    // FIXME could emit multiple instructions.
240    report_fatal_error("emitEpilogue Frame size too big: " + Twine(FrameSize));
241  }
242
243  if (FrameSize) {
244    XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
245
246    if (FP) {
247      // Restore R10
248      int FPSpillOffset = MFI->getObjectOffset(XFI->getFPSpillSlot());
249      FPSpillOffset += FrameSize*4;
250      loadFromStack(MBB, MBBI, XCore::R10, FPSpillOffset, dl, TII);
251    }
252    bool restoreLR = XFI->getUsesLR();
253    if (restoreLR && MFI->getObjectOffset(XFI->getLRSpillSlot()) != 0) {
254      int LRSpillOffset = MFI->getObjectOffset(XFI->getLRSpillSlot());
255      LRSpillOffset += FrameSize*4;
256      loadFromStack(MBB, MBBI, XCore::LR, LRSpillOffset, dl, TII);
257      restoreLR = false;
258    }
259    if (restoreLR) {
260      // Fold prologue into return instruction
261      assert(MBBI->getOpcode() == XCore::RETSP_u6
262        || MBBI->getOpcode() == XCore::RETSP_lu6);
263      int Opcode = (isU6) ? XCore::RETSP_u6 : XCore::RETSP_lu6;
264      BuildMI(MBB, MBBI, dl, TII.get(Opcode)).addImm(FrameSize);
265      MBB.erase(MBBI);
266    } else {
267      int Opcode = (isU6) ? XCore::LDAWSP_ru6_RRegs : XCore::LDAWSP_lru6_RRegs;
268      BuildMI(MBB, MBBI, dl, TII.get(Opcode), XCore::SP).addImm(FrameSize);
269    }
270  }
271}
272
273bool XCoreFrameLowering::spillCalleeSavedRegisters(MachineBasicBlock &MBB,
274                                               MachineBasicBlock::iterator MI,
275                                        const std::vector<CalleeSavedInfo> &CSI,
276                                          const TargetRegisterInfo *TRI) const {
277  if (CSI.empty())
278    return true;
279
280  MachineFunction *MF = MBB.getParent();
281  const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
282
283  XCoreFunctionInfo *XFI = MF->getInfo<XCoreFunctionInfo>();
284  bool emitFrameMoves = XCoreRegisterInfo::needsFrameMoves(*MF);
285
286  DebugLoc DL;
287  if (MI != MBB.end()) DL = MI->getDebugLoc();
288
289  for (std::vector<CalleeSavedInfo>::const_iterator it = CSI.begin();
290                                                    it != CSI.end(); ++it) {
291    // Add the callee-saved register as live-in. It's killed at the spill.
292    MBB.addLiveIn(it->getReg());
293
294    unsigned Reg = it->getReg();
295    const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
296    TII.storeRegToStackSlot(MBB, MI, Reg, true,
297                            it->getFrameIdx(), RC, TRI);
298    if (emitFrameMoves) {
299      MCSymbol *SaveLabel = MF->getContext().CreateTempSymbol();
300      BuildMI(MBB, MI, DL, TII.get(XCore::PROLOG_LABEL)).addSym(SaveLabel);
301      XFI->getSpillLabels().push_back(std::make_pair(SaveLabel, *it));
302    }
303  }
304  return true;
305}
306
307bool XCoreFrameLowering::restoreCalleeSavedRegisters(MachineBasicBlock &MBB,
308                                                 MachineBasicBlock::iterator MI,
309                                        const std::vector<CalleeSavedInfo> &CSI,
310                                            const TargetRegisterInfo *TRI) const{
311  MachineFunction *MF = MBB.getParent();
312  const TargetInstrInfo &TII = *MF->getTarget().getInstrInfo();
313
314  bool AtStart = MI == MBB.begin();
315  MachineBasicBlock::iterator BeforeI = MI;
316  if (!AtStart)
317    --BeforeI;
318  for (std::vector<CalleeSavedInfo>::const_iterator it = CSI.begin();
319                                                    it != CSI.end(); ++it) {
320    unsigned Reg = it->getReg();
321    const TargetRegisterClass *RC = TRI->getMinimalPhysRegClass(Reg);
322    TII.loadRegFromStackSlot(MBB, MI, it->getReg(), it->getFrameIdx(),
323                             RC, TRI);
324    assert(MI != MBB.begin() &&
325           "loadRegFromStackSlot didn't insert any code!");
326    // Insert in reverse order.  loadRegFromStackSlot can insert multiple
327    // instructions.
328    if (AtStart)
329      MI = MBB.begin();
330    else {
331      MI = BeforeI;
332      ++MI;
333    }
334  }
335  return true;
336}
337
338void
339XCoreFrameLowering::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
340                                                     RegScavenger *RS) const {
341  MachineFrameInfo *MFI = MF.getFrameInfo();
342  const TargetRegisterInfo *RegInfo = MF.getTarget().getRegisterInfo();
343  bool LRUsed = MF.getRegInfo().isPhysRegUsed(XCore::LR);
344  const TargetRegisterClass *RC = &XCore::GRRegsRegClass;
345  XCoreFunctionInfo *XFI = MF.getInfo<XCoreFunctionInfo>();
346  if (LRUsed) {
347    MF.getRegInfo().setPhysRegUnused(XCore::LR);
348
349    bool isVarArg = MF.getFunction()->isVarArg();
350    int FrameIdx;
351    if (! isVarArg) {
352      // A fixed offset of 0 allows us to save / restore LR using entsp / retsp.
353      FrameIdx = MFI->CreateFixedObject(RC->getSize(), 0, true);
354    } else {
355      FrameIdx = MFI->CreateStackObject(RC->getSize(), RC->getAlignment(),
356                                        false);
357    }
358    XFI->setUsesLR(FrameIdx);
359    XFI->setLRSpillSlot(FrameIdx);
360  }
361  if (RegInfo->requiresRegisterScavenging(MF)) {
362    // Reserve a slot close to SP or frame pointer.
363    RS->setScavengingFrameIndex(MFI->CreateStackObject(RC->getSize(),
364                                                       RC->getAlignment(),
365                                                       false));
366  }
367  if (hasFP(MF)) {
368    // A callee save register is used to hold the FP.
369    // This needs saving / restoring in the epilogue / prologue.
370    XFI->setFPSpillSlot(MFI->CreateStackObject(RC->getSize(),
371                                               RC->getAlignment(),
372                                               false));
373  }
374}
375
376void XCoreFrameLowering::
377processFunctionBeforeFrameFinalized(MachineFunction &MF) const {
378
379}
380