SystemZRegisterInfo.cpp revision ef5decab535f0f45cff45abf156294d3be495660 
1//===- SystemZRegisterInfo.cpp - SystemZ Register Information -------*- C++ -*-===//
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 the SystemZ implementation of the TargetRegisterInfo class.
11//
12//===----------------------------------------------------------------------===//
13
14#include "SystemZ.h"
15#include "SystemZMachineFunctionInfo.h"
16#include "SystemZRegisterInfo.h"
17#include "SystemZSubtarget.h"
18#include "llvm/CodeGen/MachineInstrBuilder.h"
19#include "llvm/CodeGen/MachineFrameInfo.h"
20#include "llvm/CodeGen/MachineFunction.h"
21#include "llvm/CodeGen/MachineRegisterInfo.h"
22#include "llvm/Target/TargetFrameInfo.h"
23#include "llvm/Target/TargetInstrInfo.h"
24#include "llvm/Target/TargetMachine.h"
25#include "llvm/Target/TargetOptions.h"
26#include "llvm/ADT/BitVector.h"
27using namespace llvm;
28
29SystemZRegisterInfo::SystemZRegisterInfo(SystemZTargetMachine &tm,
30                                         const TargetInstrInfo &tii)
31  : SystemZGenRegisterInfo(SystemZ::ADJCALLSTACKUP, SystemZ::ADJCALLSTACKDOWN),
32    TM(tm), TII(tii) {
33}
34
35const unsigned*
36SystemZRegisterInfo::getCalleeSavedRegs(const MachineFunction *MF) const {
37  static const unsigned CalleeSavedRegs[] = {
38    SystemZ::R6D,  SystemZ::R7D,  SystemZ::R8D,  SystemZ::R9D,
39    SystemZ::R10D, SystemZ::R11D, SystemZ::R12D, SystemZ::R13D,
40    SystemZ::R14D, SystemZ::R15D,
41    SystemZ::F1,  SystemZ::F3,  SystemZ::F5,  SystemZ::F7,
42    0
43  };
44
45  return CalleeSavedRegs;
46}
47
48const TargetRegisterClass* const*
49SystemZRegisterInfo::getCalleeSavedRegClasses(const MachineFunction *MF) const {
50  static const TargetRegisterClass * const CalleeSavedRegClasses[] = {
51    &SystemZ::GR64RegClass, &SystemZ::GR64RegClass,
52    &SystemZ::GR64RegClass, &SystemZ::GR64RegClass,
53    &SystemZ::GR64RegClass, &SystemZ::GR64RegClass,
54    &SystemZ::GR64RegClass, &SystemZ::GR64RegClass,
55    &SystemZ::GR64RegClass, &SystemZ::GR64RegClass,
56    &SystemZ::FP64RegClass, &SystemZ::FP64RegClass,
57    &SystemZ::FP64RegClass, &SystemZ::FP64RegClass, 0
58  };
59  return CalleeSavedRegClasses;
60}
61
62BitVector SystemZRegisterInfo::getReservedRegs(const MachineFunction &MF) const {
63  BitVector Reserved(getNumRegs());
64  if (hasFP(MF))
65    Reserved.set(SystemZ::R11D);
66  Reserved.set(SystemZ::R14D);
67  Reserved.set(SystemZ::R15D);
68  return Reserved;
69}
70
71/// needsFP - Return true if the specified function should have a dedicated
72/// frame pointer register.  This is true if the function has variable sized
73/// allocas or if frame pointer elimination is disabled.
74bool SystemZRegisterInfo::hasFP(const MachineFunction &MF) const {
75  const MachineFrameInfo *MFI = MF.getFrameInfo();
76  return NoFramePointerElim || MFI->hasVarSizedObjects();
77}
78
79bool SystemZRegisterInfo::hasReservedCallFrame(MachineFunction &MF) const {
80  // FIXME: Should we always have reserved call frame?
81  return !MF.getFrameInfo()->hasVarSizedObjects();
82}
83
84void SystemZRegisterInfo::
85eliminateCallFramePseudoInstr(MachineFunction &MF, MachineBasicBlock &MBB,
86                              MachineBasicBlock::iterator I) const {
87  if (!hasReservedCallFrame(MF)) {
88    assert(0 && "Not implemented yet!");
89  }
90
91  MBB.erase(I);
92}
93
94int SystemZRegisterInfo::getFrameIndexOffset(MachineFunction &MF, int FI) const {
95  const TargetFrameInfo &TFI = *MF.getTarget().getFrameInfo();
96  MachineFrameInfo *MFI = MF.getFrameInfo();
97  SystemZMachineFunctionInfo *SystemZMFI =
98    MF.getInfo<SystemZMachineFunctionInfo>();
99  int Offset = MFI->getObjectOffset(FI) + MFI->getOffsetAdjustment();
100  uint64_t StackSize = MFI->getStackSize();
101
102  // Fixed objects are really located in the "previous" frame.
103  if (FI < 0)
104    StackSize -= SystemZMFI->getCalleeSavedFrameSize();
105
106  Offset += StackSize - TFI.getOffsetOfLocalArea();
107
108  // Skip the register save area if we generated the stack frame.
109  if (StackSize)
110    Offset -= TFI.getOffsetOfLocalArea();
111
112  return Offset;
113}
114
115void SystemZRegisterInfo::eliminateFrameIndex(MachineBasicBlock::iterator II,
116                                            int SPAdj, RegScavenger *RS) const {
117  assert(SPAdj == 0 && "Unxpected");
118
119  unsigned i = 0;
120  MachineInstr &MI = *II;
121  MachineFunction &MF = *MI.getParent()->getParent();
122  while (!MI.getOperand(i).isFI()) {
123    ++i;
124    assert(i < MI.getNumOperands() && "Instr doesn't have FrameIndex operand!");
125  }
126
127  int FrameIndex = MI.getOperand(i).getIndex();
128
129  unsigned BasePtr = (hasFP(MF) ? SystemZ::R11D : SystemZ::R15D);
130
131  // This must be part of a rri or ri operand memory reference.  Replace the
132  // FrameIndex with base register with BasePtr.  Add an offset to the
133  // displacement field.
134  MI.getOperand(i).ChangeToRegister(BasePtr, false);
135
136  // Offset is a 20-bit integer.
137  // FIXME: handle "too long" displacements.
138  int Offset = getFrameIndexOffset(MF, FrameIndex) + MI.getOperand(i+1).getImm();
139  MI.getOperand(i+1).ChangeToImmediate(Offset);
140}
141
142void
143SystemZRegisterInfo::processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
144                                                       RegScavenger *RS) const {
145  // Determine whether R15/R14 will ever be clobbered inside the function. And
146  // if yes - mark it as 'callee' saved.
147  MachineFrameInfo *FFI = MF.getFrameInfo();
148
149  if (FFI->hasCalls()
150      /* FIXME: function is varargs */
151      /* FIXME: function grabs RA */
152      /* FIXME: function calls eh_return */)
153    MF.getRegInfo().setPhysRegUsed(SystemZ::R14D);
154
155  if (FFI->getObjectIndexEnd() != 0 || // Contains automatic variables
156      FFI->hasVarSizedObjects() // Function calls dynamic alloca's
157      /* FIXME: function is varargs */)
158    MF.getRegInfo().setPhysRegUsed(SystemZ::R15D);
159}
160
161/// emitSPUpdate - Emit a series of instructions to increment / decrement the
162/// stack pointer by a constant value.
163static
164void emitSPUpdate(MachineBasicBlock &MBB, MachineBasicBlock::iterator &MBBI,
165                  int64_t NumBytes, const TargetInstrInfo &TII) {
166  // FIXME: Handle different stack sizes here.
167  bool isSub = NumBytes < 0;
168  uint64_t Offset = isSub ? -NumBytes : NumBytes;
169  unsigned Opc = SystemZ::ADD64ri16;
170  uint64_t Chunk = (1LL << 15) - 1;
171  DebugLoc DL = (MBBI != MBB.end() ? MBBI->getDebugLoc() :
172                 DebugLoc::getUnknownLoc());
173
174  while (Offset) {
175    uint64_t ThisVal = (Offset > Chunk) ? Chunk : Offset;
176    MachineInstr *MI =
177      BuildMI(MBB, MBBI, DL, TII.get(Opc), SystemZ::R15D)
178      .addReg(SystemZ::R15D).addImm((isSub ? -(int64_t)ThisVal : ThisVal));
179    // The PSW implicit def is dead.
180    MI->getOperand(3).setIsDead();
181    Offset -= ThisVal;
182  }
183}
184
185void SystemZRegisterInfo::emitPrologue(MachineFunction &MF) const {
186  MachineBasicBlock &MBB = MF.front();   // Prolog goes in entry BB
187  const TargetFrameInfo &TFI = *MF.getTarget().getFrameInfo();
188  MachineFrameInfo *MFI = MF.getFrameInfo();
189  SystemZMachineFunctionInfo *SystemZMFI =
190    MF.getInfo<SystemZMachineFunctionInfo>();
191  MachineBasicBlock::iterator MBBI = MBB.begin();
192  DebugLoc DL = (MBBI != MBB.end() ? MBBI->getDebugLoc() :
193                 DebugLoc::getUnknownLoc());
194
195  // Get the number of bytes to allocate from the FrameInfo.
196  // Note that area for callee-saved stuff is already allocated, thus we need to
197  // 'undo' the stack movement.
198  uint64_t StackSize =
199    MFI->getStackSize() - SystemZMFI->getCalleeSavedFrameSize();
200
201  // Skip the callee-saved push instructions.
202  while (MBBI != MBB.end() &&
203         (MBBI->getOpcode() == SystemZ::MOV64mr ||
204          MBBI->getOpcode() == SystemZ::MOV64mrm))
205    ++MBBI;
206
207  if (MBBI != MBB.end())
208    DL = MBBI->getDebugLoc();
209
210  uint64_t NumBytes = StackSize - TFI.getOffsetOfLocalArea();
211
212  if (StackSize) // adjust stack pointer: R15 -= numbytes
213    emitSPUpdate(MBB, MBBI, -(int64_t)NumBytes, TII);
214
215  if (hasFP(MF)) {
216    // Update R11 with the new base value...
217    BuildMI(MBB, MBBI, DL, TII.get(SystemZ::MOV64rr), SystemZ::R11D)
218      .addReg(SystemZ::R15D);
219
220    // Mark the FramePtr as live-in in every block except the entry.
221    for (MachineFunction::iterator I = next(MF.begin()), E = MF.end();
222         I != E; ++I)
223      I->addLiveIn(SystemZ::R11D);
224
225  }
226}
227
228void SystemZRegisterInfo::emitEpilogue(MachineFunction &MF,
229                                     MachineBasicBlock &MBB) const {
230  const MachineFrameInfo *MFI = MF.getFrameInfo();
231  const TargetFrameInfo &TFI = *MF.getTarget().getFrameInfo();
232  MachineBasicBlock::iterator MBBI = prior(MBB.end());
233  SystemZMachineFunctionInfo *SystemZMFI =
234    MF.getInfo<SystemZMachineFunctionInfo>();
235  unsigned RetOpcode = MBBI->getOpcode();
236  DebugLoc DL = MBBI->getDebugLoc();
237
238  switch (RetOpcode) {
239  case SystemZ::RET: break;  // These are ok
240  default:
241    assert(0 && "Can only insert epilog into returning blocks");
242  }
243
244  // Get the number of bytes to allocate from the FrameInfo
245  // Note that area for callee-saved stuff is already allocated, thus we need to
246  // 'undo' the stack movement.
247  uint64_t StackSize =
248    MFI->getStackSize() - SystemZMFI->getCalleeSavedFrameSize();
249  uint64_t NumBytes = StackSize - TFI.getOffsetOfLocalArea();
250
251  // Skip the final terminator instruction.
252  while (MBBI != MBB.begin()) {
253    MachineBasicBlock::iterator PI = prior(MBBI);
254    --MBBI;
255    if (!PI->getDesc().isTerminator())
256      break;
257  }
258
259  // During callee-saved restores emission stack frame was not yet finialized
260  // (and thus - the stack size was unknown). Tune the offset having full stack
261  // size in hands.
262  if (SystemZMFI->getCalleeSavedFrameSize()) {
263    assert((MBBI->getOpcode() == SystemZ::MOV64rmm ||
264            MBBI->getOpcode() == SystemZ::MOV64rm) &&
265           "Expected to see callee-save register restore code");
266
267    unsigned i = 0;
268    MachineInstr &MI = *MBBI;
269    while (!MI.getOperand(i).isImm()) {
270      ++i;
271      assert(i < MI.getNumOperands() && "Unexpected restore code!");
272    }
273
274    MI.getOperand(i).ChangeToImmediate(NumBytes + MI.getOperand(i).getImm());
275  }
276}
277
278unsigned SystemZRegisterInfo::getRARegister() const {
279  assert(0 && "What is the return address register");
280  return 0;
281}
282
283unsigned SystemZRegisterInfo::getFrameRegister(MachineFunction &MF) const {
284  assert(0 && "What is the frame register");
285  return 0;
286}
287
288unsigned SystemZRegisterInfo::getEHExceptionRegister() const {
289  assert(0 && "What is the exception register");
290  return 0;
291}
292
293unsigned SystemZRegisterInfo::getEHHandlerRegister() const {
294  assert(0 && "What is the exception handler register");
295  return 0;
296}
297
298int SystemZRegisterInfo::getDwarfRegNum(unsigned RegNum, bool isEH) const {
299  assert(0 && "What is the dwarf register number");
300  return -1;
301}
302
303#include "SystemZGenRegisterInfo.inc"
304