summaryrefslogtreecommitdiff
path: root/lib/Target/MBlaze/MBlazeFrameLowering.cpp
blob: b6edbba2a7f9217d8eaaaee736b2d0620159276d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
//===-- MBlazeFrameLowering.cpp - MBlaze 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 MBlaze implementation of TargetFrameLowering class.
//
//===----------------------------------------------------------------------===//

#define DEBUG_TYPE "mblaze-frame-lowering"

#include "MBlazeFrameLowering.h"
#include "InstPrinter/MBlazeInstPrinter.h"
#include "MBlazeInstrInfo.h"
#include "MBlazeMachineFunction.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/IR/DataLayout.h"
#include "llvm/IR/Function.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Target/TargetOptions.h"

using namespace llvm;

static cl::opt<bool> MBDisableStackAdjust(
  "disable-mblaze-stack-adjust",
  cl::init(false),
  cl::desc("Disable MBlaze stack layout adjustment."),
  cl::Hidden);

static void replaceFrameIndexes(MachineFunction &MF, 
                                SmallVector<std::pair<int,int64_t>, 16> &FR) {
  MachineFrameInfo *MFI = MF.getFrameInfo();
  MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
  const SmallVector<std::pair<int,int64_t>, 16>::iterator FRB = FR.begin();
  const SmallVector<std::pair<int,int64_t>, 16>::iterator FRE = FR.end();

  SmallVector<std::pair<int,int64_t>, 16>::iterator FRI = FRB;
  for (; FRI != FRE; ++FRI) {
    MFI->RemoveStackObject(FRI->first);
    int NFI = MFI->CreateFixedObject(4, FRI->second, true);
    MBlazeFI->recordReplacement(FRI->first, NFI);

    for (MachineFunction::iterator MB=MF.begin(), ME=MF.end(); MB!=ME; ++MB) {
      MachineBasicBlock::iterator MBB = MB->begin();
      const MachineBasicBlock::iterator MBE = MB->end();

      for (; MBB != MBE; ++MBB) {
        MachineInstr::mop_iterator MIB = MBB->operands_begin();
        const MachineInstr::mop_iterator MIE = MBB->operands_end();

        for (MachineInstr::mop_iterator MII = MIB; MII != MIE; ++MII) {
          if (!MII->isFI() || MII->getIndex() != FRI->first) continue;
          DEBUG(dbgs() << "FOUND FI#" << MII->getIndex() << "\n");
          MII->setIndex(NFI);
        }
      }
    }
  }
}

//===----------------------------------------------------------------------===//
//
// Stack Frame Processing methods
// +----------------------------+
//
// The stack is allocated decrementing the stack pointer on
// the first instruction of a function prologue. Once decremented,
// all stack references are are done through a positive offset
// from the stack/frame pointer, so the stack is considered
// to grow up.
//
//===----------------------------------------------------------------------===//

static void analyzeFrameIndexes(MachineFunction &MF) {
  if (MBDisableStackAdjust) return;

  MachineFrameInfo *MFI = MF.getFrameInfo();
  MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
  const MachineRegisterInfo &MRI = MF.getRegInfo();

  MachineRegisterInfo::livein_iterator LII = MRI.livein_begin();
  MachineRegisterInfo::livein_iterator LIE = MRI.livein_end();
  const SmallVector<int, 16> &LiveInFI = MBlazeFI->getLiveIn();
  SmallVector<MachineInstr*, 16> EraseInstr;
  SmallVector<std::pair<int,int64_t>, 16> FrameRelocate;

  MachineBasicBlock *MBB = MF.getBlockNumbered(0);
  MachineBasicBlock::iterator MIB = MBB->begin();
  MachineBasicBlock::iterator MIE = MBB->end();

  int StackAdjust = 0;
  int StackOffset = -28;

  // In this loop we are searching frame indexes that corrospond to incoming
  // arguments that are already in the stack. We look for instruction sequences
  // like the following:
  //    
  //    LWI REG, FI1, 0
  //    ...
  //    SWI REG, FI2, 0
  //
  // As long as there are no defs of REG in the ... part, we can eliminate
  // the SWI instruction because the value has already been stored to the
  // stack by the caller. All we need to do is locate FI at the correct
  // stack location according to the calling convensions.
  //
  // Additionally, if the SWI operation kills the def of REG then we don't
  // need the LWI operation so we can erase it as well.
  for (unsigned i = 0, e = LiveInFI.size(); i < e; ++i) {
    for (MachineBasicBlock::iterator I=MIB; I != MIE; ++I) {
      if (I->getOpcode() != MBlaze::LWI || I->getNumOperands() != 3 ||
          !I->getOperand(1).isFI() || !I->getOperand(0).isReg() ||
          I->getOperand(1).getIndex() != LiveInFI[i]) continue;

      unsigned FIReg = I->getOperand(0).getReg();
      MachineBasicBlock::iterator SI = I;
      for (SI++; SI != MIE; ++SI) {
        if (!SI->getOperand(0).isReg() ||
            !SI->getOperand(1).isFI() ||
            SI->getOpcode() != MBlaze::SWI) continue;

        int FI = SI->getOperand(1).getIndex();
        if (SI->getOperand(0).getReg() != FIReg ||
            MFI->isFixedObjectIndex(FI) ||
            MFI->getObjectSize(FI) != 4) continue;

        if (SI->getOperand(0).isDef()) break;

        if (SI->getOperand(0).isKill()) {
          DEBUG(dbgs() << "LWI for FI#" << I->getOperand(1).getIndex() 
                       << " removed\n");
          EraseInstr.push_back(I);
        }

        EraseInstr.push_back(SI);
        DEBUG(dbgs() << "SWI for FI#" << FI << " removed\n");

        FrameRelocate.push_back(std::make_pair(FI,StackOffset));
        DEBUG(dbgs() << "FI#" << FI << " relocated to " << StackOffset << "\n");

        StackOffset -= 4;
        StackAdjust += 4;
        break;
      }
    }
  }

  // In this loop we are searching for frame indexes that corrospond to
  // incoming arguments that are in registers. We look for instruction
  // sequences like the following:
  //    
  //    ...  SWI REG, FI, 0
  // 
  // As long as the ... part does not define REG and if REG is an incoming
  // parameter register then we know that, according to ABI convensions, the
  // caller has allocated stack space for it already.  Instead of allocating
  // stack space on our frame, we record the correct location in the callers
  // frame.
  for (MachineRegisterInfo::livein_iterator LI = LII; LI != LIE; ++LI) {
    for (MachineBasicBlock::iterator I=MIB; I != MIE; ++I) {
      if (I->definesRegister(LI->first))
        break;

      if (I->getOpcode() != MBlaze::SWI || I->getNumOperands() != 3 ||
          !I->getOperand(1).isFI() || !I->getOperand(0).isReg() ||
          I->getOperand(1).getIndex() < 0) continue;

      if (I->getOperand(0).getReg() == LI->first) {
        int FI = I->getOperand(1).getIndex();
        MBlazeFI->recordLiveIn(FI);

        int FILoc = 0;
        switch (LI->first) {
        default: llvm_unreachable("invalid incoming parameter!");
        case MBlaze::R5:  FILoc = -4; break;
        case MBlaze::R6:  FILoc = -8; break;
        case MBlaze::R7:  FILoc = -12; break;
        case MBlaze::R8:  FILoc = -16; break;
        case MBlaze::R9:  FILoc = -20; break;
        case MBlaze::R10: FILoc = -24; break;
        }

        StackAdjust += 4;
        FrameRelocate.push_back(std::make_pair(FI,FILoc));
        DEBUG(dbgs() << "FI#" << FI << " relocated to " << FILoc << "\n");
        break;
      }
    }
  }

  // Go ahead and erase all of the instructions that we determined were
  // no longer needed.
  for (int i = 0, e = EraseInstr.size(); i < e; ++i)
    MBB->erase(EraseInstr[i]);

  // Replace all of the frame indexes that we have relocated with new
  // fixed object frame indexes.
  replaceFrameIndexes(MF, FrameRelocate);
}

static void interruptFrameLayout(MachineFunction &MF) {
  const Function *F = MF.getFunction();
  CallingConv::ID CallConv = F->getCallingConv();

  // If this function is not using either the interrupt_handler
  // calling convention or the save_volatiles calling convention
  // then we don't need to do any additional frame layout.
  if (CallConv != CallingConv::MBLAZE_INTR &&
      CallConv != CallingConv::MBLAZE_SVOL)
      return;

  MachineFrameInfo *MFI = MF.getFrameInfo();
  const MachineRegisterInfo &MRI = MF.getRegInfo();
  const MBlazeInstrInfo &TII =
    *static_cast<const MBlazeInstrInfo*>(MF.getTarget().getInstrInfo());

  // Determine if the calling convention is the interrupt_handler
  // calling convention. Some pieces of the prologue and epilogue
  // only need to be emitted if we are lowering and interrupt handler.
  bool isIntr = CallConv == CallingConv::MBLAZE_INTR;

  // Determine where to put prologue and epilogue additions
  MachineBasicBlock &MENT   = MF.front();
  MachineBasicBlock &MEXT   = MF.back();

  MachineBasicBlock::iterator MENTI = MENT.begin();
  MachineBasicBlock::iterator MEXTI = prior(MEXT.end());

  DebugLoc ENTDL = MENTI != MENT.end() ? MENTI->getDebugLoc() : DebugLoc();
  DebugLoc EXTDL = MEXTI != MEXT.end() ? MEXTI->getDebugLoc() : DebugLoc();

  // Store the frame indexes generated during prologue additions for use
  // when we are generating the epilogue additions.
  SmallVector<int, 10> VFI;

  // Build the prologue SWI for R3 - R12 if needed. Note that R11 must
  // always have a SWI because it is used when processing RMSR.
  for (unsigned r = MBlaze::R3; r <= MBlaze::R12; ++r) {
    if (!MRI.isPhysRegUsed(r) && !(isIntr && r == MBlaze::R11)) continue;
    
    int FI = MFI->CreateStackObject(4,4,false,false);
    VFI.push_back(FI);

    BuildMI(MENT, MENTI, ENTDL, TII.get(MBlaze::SWI), r)
      .addFrameIndex(FI).addImm(0);
  }
    
  // Build the prologue SWI for R17, R18
  int R17FI = MFI->CreateStackObject(4,4,false,false);
  int R18FI = MFI->CreateStackObject(4,4,false,false);

  BuildMI(MENT, MENTI, ENTDL, TII.get(MBlaze::SWI), MBlaze::R17)
    .addFrameIndex(R17FI).addImm(0);
    
  BuildMI(MENT, MENTI, ENTDL, TII.get(MBlaze::SWI), MBlaze::R18)
    .addFrameIndex(R18FI).addImm(0);

  // Buid the prologue SWI and the epilogue LWI for RMSR if needed
  if (isIntr) {
    int MSRFI = MFI->CreateStackObject(4,4,false,false);
    BuildMI(MENT, MENTI, ENTDL, TII.get(MBlaze::MFS), MBlaze::R11)
      .addReg(MBlaze::RMSR);
    BuildMI(MENT, MENTI, ENTDL, TII.get(MBlaze::SWI), MBlaze::R11)
      .addFrameIndex(MSRFI).addImm(0);

    BuildMI(MEXT, MEXTI, EXTDL, TII.get(MBlaze::LWI), MBlaze::R11)
      .addFrameIndex(MSRFI).addImm(0);
    BuildMI(MEXT, MEXTI, EXTDL, TII.get(MBlaze::MTS), MBlaze::RMSR)
      .addReg(MBlaze::R11);
  }

  // Build the epilogue LWI for R17, R18
  BuildMI(MEXT, MEXTI, EXTDL, TII.get(MBlaze::LWI), MBlaze::R18)
    .addFrameIndex(R18FI).addImm(0);

  BuildMI(MEXT, MEXTI, EXTDL, TII.get(MBlaze::LWI), MBlaze::R17)
    .addFrameIndex(R17FI).addImm(0);

  // Build the epilogue LWI for R3 - R12 if needed
  for (unsigned r = MBlaze::R12, i = VFI.size(); r >= MBlaze::R3; --r) {
    if (!MRI.isPhysRegUsed(r)) continue;
    BuildMI(MEXT, MEXTI, EXTDL, TII.get(MBlaze::LWI), r)
      .addFrameIndex(VFI[--i]).addImm(0);
  }
}

static void determineFrameLayout(MachineFunction &MF) {
  MachineFrameInfo *MFI = MF.getFrameInfo();
  MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();

  // Replace the dummy '0' SPOffset by the negative offsets, as explained on
  // LowerFORMAL_ARGUMENTS. Leaving '0' for while is necessary to avoid
  // the approach done by calculateFrameObjectOffsets to the stack frame.
  MBlazeFI->adjustLoadArgsFI(MFI);
  MBlazeFI->adjustStoreVarArgsFI(MFI);

  // Get the number of bytes to allocate from the FrameInfo
  unsigned FrameSize = MFI->getStackSize();
  DEBUG(dbgs() << "Original Frame Size: " << FrameSize << "\n" );

  // Get the alignments provided by the target, and the maximum alignment
  // (if any) of the fixed frame objects.
  // unsigned MaxAlign = MFI->getMaxAlignment();
  unsigned TargetAlign = MF.getTarget().getFrameLowering()->getStackAlignment();
  unsigned AlignMask = TargetAlign - 1;

  // Make sure the frame is aligned.
  FrameSize = (FrameSize + AlignMask) & ~AlignMask;
  MFI->setStackSize(FrameSize);
  DEBUG(dbgs() << "Aligned Frame Size: " << FrameSize << "\n" );
}

int MBlazeFrameLowering::getFrameIndexOffset(const MachineFunction &MF, int FI) 
  const {
  const MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
  if (MBlazeFI->hasReplacement(FI))
    FI = MBlazeFI->getReplacement(FI);
  return TargetFrameLowering::getFrameIndexOffset(MF,FI);
}

// hasFP - 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 MBlazeFrameLowering::hasFP(const MachineFunction &MF) const {
  const MachineFrameInfo *MFI = MF.getFrameInfo();
  return MF.getTarget().Options.DisableFramePointerElim(MF) ||
         MFI->hasVarSizedObjects();
}

void MBlazeFrameLowering::emitPrologue(MachineFunction &MF) const {
  MachineBasicBlock &MBB   = MF.front();
  MachineFrameInfo *MFI    = MF.getFrameInfo();
  const MBlazeInstrInfo &TII =
    *static_cast<const MBlazeInstrInfo*>(MF.getTarget().getInstrInfo());
  MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
  MachineBasicBlock::iterator MBBI = MBB.begin();
  DebugLoc DL = MBBI != MBB.end() ? MBBI->getDebugLoc() : DebugLoc();

  CallingConv::ID CallConv = MF.getFunction()->getCallingConv();
  bool requiresRA = CallConv == CallingConv::MBLAZE_INTR;

  // Determine the correct frame layout
  determineFrameLayout(MF);

  // Get the number of bytes to allocate from the FrameInfo.
  unsigned StackSize = MFI->getStackSize();

  // No need to allocate space on the stack.
  if (StackSize == 0 && !MFI->adjustsStack() && !requiresRA) return;

  int FPOffset = MBlazeFI->getFPStackOffset();
  int RAOffset = MBlazeFI->getRAStackOffset();

  // Adjust stack : addi R1, R1, -imm
  BuildMI(MBB, MBBI, DL, TII.get(MBlaze::ADDIK), MBlaze::R1)
      .addReg(MBlaze::R1).addImm(-StackSize);

  // swi  R15, R1, stack_loc
  if (MFI->adjustsStack() || requiresRA) {
    BuildMI(MBB, MBBI, DL, TII.get(MBlaze::SWI))
        .addReg(MBlaze::R15).addReg(MBlaze::R1).addImm(RAOffset);
  }

  if (hasFP(MF)) {
    // swi  R19, R1, stack_loc
    BuildMI(MBB, MBBI, DL, TII.get(MBlaze::SWI))
      .addReg(MBlaze::R19).addReg(MBlaze::R1).addImm(FPOffset);

    // add R19, R1, R0
    BuildMI(MBB, MBBI, DL, TII.get(MBlaze::ADD), MBlaze::R19)
      .addReg(MBlaze::R1).addReg(MBlaze::R0);
  }
}

void MBlazeFrameLowering::emitEpilogue(MachineFunction &MF,
                                   MachineBasicBlock &MBB) const {
  MachineBasicBlock::iterator MBBI = MBB.getLastNonDebugInstr();
  MachineFrameInfo *MFI            = MF.getFrameInfo();
  MBlazeFunctionInfo *MBlazeFI     = MF.getInfo<MBlazeFunctionInfo>();
  const MBlazeInstrInfo &TII =
    *static_cast<const MBlazeInstrInfo*>(MF.getTarget().getInstrInfo());

  DebugLoc dl = MBBI->getDebugLoc();

  CallingConv::ID CallConv = MF.getFunction()->getCallingConv();
  bool requiresRA = CallConv == CallingConv::MBLAZE_INTR;

  // Get the FI's where RA and FP are saved.
  int FPOffset = MBlazeFI->getFPStackOffset();
  int RAOffset = MBlazeFI->getRAStackOffset();

  if (hasFP(MF)) {
    // add R1, R19, R0
    BuildMI(MBB, MBBI, dl, TII.get(MBlaze::ADD), MBlaze::R1)
      .addReg(MBlaze::R19).addReg(MBlaze::R0);

    // lwi  R19, R1, stack_loc
    BuildMI(MBB, MBBI, dl, TII.get(MBlaze::LWI), MBlaze::R19)
      .addReg(MBlaze::R1).addImm(FPOffset);
  }

  // lwi R15, R1, stack_loc
  if (MFI->adjustsStack() || requiresRA) {
    BuildMI(MBB, MBBI, dl, TII.get(MBlaze::LWI), MBlaze::R15)
      .addReg(MBlaze::R1).addImm(RAOffset);
  }

  // Get the number of bytes from FrameInfo
  int StackSize = (int) MFI->getStackSize();

  // addi R1, R1, imm
  if (StackSize) {
    BuildMI(MBB, MBBI, dl, TII.get(MBlaze::ADDIK), MBlaze::R1)
      .addReg(MBlaze::R1).addImm(StackSize);
  }
}

void MBlazeFrameLowering::
processFunctionBeforeCalleeSavedScan(MachineFunction &MF,
                                     RegScavenger *RS) const {
  MachineFrameInfo *MFI = MF.getFrameInfo();
  MBlazeFunctionInfo *MBlazeFI = MF.getInfo<MBlazeFunctionInfo>();
  CallingConv::ID CallConv = MF.getFunction()->getCallingConv();
  bool requiresRA = CallConv == CallingConv::MBLAZE_INTR;

  if (MFI->adjustsStack() || requiresRA) {
    MBlazeFI->setRAStackOffset(0);
    MFI->CreateFixedObject(4,0,true);
  }

  if (hasFP(MF)) {
    MBlazeFI->setFPStackOffset(4);
    MFI->CreateFixedObject(4,4,true);
  }

  interruptFrameLayout(MF);
  analyzeFrameIndexes(MF);
}