LLVM  3.7.0
MipsConstantIslandPass.cpp
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1 //===-- MipsConstantIslandPass.cpp - Emit Pc Relative loads----------------===//
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 //
11 // This pass is used to make Pc relative loads of constants.
12 // For now, only Mips16 will use this.
13 //
14 // Loading constants inline is expensive on Mips16 and it's in general better
15 // to place the constant nearby in code space and then it can be loaded with a
16 // simple 16 bit load instruction.
17 //
18 // The constants can be not just numbers but addresses of functions and labels.
19 // This can be particularly helpful in static relocation mode for embedded
20 // non-linux targets.
21 //
22 //
23 
24 #include "Mips.h"
26 #include "Mips16InstrInfo.h"
27 #include "MipsMachineFunction.h"
28 #include "MipsTargetMachine.h"
29 #include "llvm/ADT/Statistic.h"
35 #include "llvm/IR/Function.h"
36 #include "llvm/IR/InstIterator.h"
38 #include "llvm/Support/Debug.h"
39 #include "llvm/Support/Format.h"
45 #include <algorithm>
46 
47 using namespace llvm;
48 
49 #define DEBUG_TYPE "mips-constant-islands"
50 
51 STATISTIC(NumCPEs, "Number of constpool entries");
52 STATISTIC(NumSplit, "Number of uncond branches inserted");
53 STATISTIC(NumCBrFixed, "Number of cond branches fixed");
54 STATISTIC(NumUBrFixed, "Number of uncond branches fixed");
55 
56 // FIXME: This option should be removed once it has received sufficient testing.
57 static cl::opt<bool>
58 AlignConstantIslands("mips-align-constant-islands", cl::Hidden, cl::init(true),
59  cl::desc("Align constant islands in code"));
60 
61 
62 // Rather than do make check tests with huge amounts of code, we force
63 // the test to use this amount.
64 //
66  "mips-constant-islands-small-offset",
67  cl::init(0),
68  cl::desc("Make small offsets be this amount for testing purposes"),
69  cl::Hidden);
70 
71 //
72 // For testing purposes we tell it to not use relaxed load forms so that it
73 // will split blocks.
74 //
76  "mips-constant-islands-no-load-relaxation",
77  cl::init(false),
78  cl::desc("Don't relax loads to long loads - for testing purposes"),
79  cl::Hidden);
80 
81 static unsigned int branchTargetOperand(MachineInstr *MI) {
82  switch (MI->getOpcode()) {
83  case Mips::Bimm16:
84  case Mips::BimmX16:
85  case Mips::Bteqz16:
86  case Mips::BteqzX16:
87  case Mips::Btnez16:
88  case Mips::BtnezX16:
89  case Mips::JalB16:
90  return 0;
91  case Mips::BeqzRxImm16:
92  case Mips::BeqzRxImmX16:
93  case Mips::BnezRxImm16:
94  case Mips::BnezRxImmX16:
95  return 1;
96  }
97  llvm_unreachable("Unknown branch type");
98 }
99 
100 static bool isUnconditionalBranch(unsigned int Opcode) {
101  switch (Opcode) {
102  default: return false;
103  case Mips::Bimm16:
104  case Mips::BimmX16:
105  case Mips::JalB16:
106  return true;
107  }
108 }
109 
110 static unsigned int longformBranchOpcode(unsigned int Opcode) {
111  switch (Opcode) {
112  case Mips::Bimm16:
113  case Mips::BimmX16:
114  return Mips::BimmX16;
115  case Mips::Bteqz16:
116  case Mips::BteqzX16:
117  return Mips::BteqzX16;
118  case Mips::Btnez16:
119  case Mips::BtnezX16:
120  return Mips::BtnezX16;
121  case Mips::JalB16:
122  return Mips::JalB16;
123  case Mips::BeqzRxImm16:
124  case Mips::BeqzRxImmX16:
125  return Mips::BeqzRxImmX16;
126  case Mips::BnezRxImm16:
127  case Mips::BnezRxImmX16:
128  return Mips::BnezRxImmX16;
129  }
130  llvm_unreachable("Unknown branch type");
131 }
132 
133 //
134 // FIXME: need to go through this whole constant islands port and check the math
135 // for branch ranges and clean this up and make some functions to calculate things
136 // that are done many times identically.
137 // Need to refactor some of the code to call this routine.
138 //
139 static unsigned int branchMaxOffsets(unsigned int Opcode) {
140  unsigned Bits, Scale;
141  switch (Opcode) {
142  case Mips::Bimm16:
143  Bits = 11;
144  Scale = 2;
145  break;
146  case Mips::BimmX16:
147  Bits = 16;
148  Scale = 2;
149  break;
150  case Mips::BeqzRxImm16:
151  Bits = 8;
152  Scale = 2;
153  break;
154  case Mips::BeqzRxImmX16:
155  Bits = 16;
156  Scale = 2;
157  break;
158  case Mips::BnezRxImm16:
159  Bits = 8;
160  Scale = 2;
161  break;
162  case Mips::BnezRxImmX16:
163  Bits = 16;
164  Scale = 2;
165  break;
166  case Mips::Bteqz16:
167  Bits = 8;
168  Scale = 2;
169  break;
170  case Mips::BteqzX16:
171  Bits = 16;
172  Scale = 2;
173  break;
174  case Mips::Btnez16:
175  Bits = 8;
176  Scale = 2;
177  break;
178  case Mips::BtnezX16:
179  Bits = 16;
180  Scale = 2;
181  break;
182  default:
183  llvm_unreachable("Unknown branch type");
184  }
185  unsigned MaxOffs = ((1 << (Bits-1))-1) * Scale;
186  return MaxOffs;
187 }
188 
189 namespace {
190 
191 
192  typedef MachineBasicBlock::iterator Iter;
193  typedef MachineBasicBlock::reverse_iterator ReverseIter;
194 
195  /// MipsConstantIslands - Due to limited PC-relative displacements, Mips
196  /// requires constant pool entries to be scattered among the instructions
197  /// inside a function. To do this, it completely ignores the normal LLVM
198  /// constant pool; instead, it places constants wherever it feels like with
199  /// special instructions.
200  ///
201  /// The terminology used in this pass includes:
202  /// Islands - Clumps of constants placed in the function.
203  /// Water - Potential places where an island could be formed.
204  /// CPE - A constant pool entry that has been placed somewhere, which
205  /// tracks a list of users.
206 
207  class MipsConstantIslands : public MachineFunctionPass {
208 
209  /// BasicBlockInfo - Information about the offset and size of a single
210  /// basic block.
211  struct BasicBlockInfo {
212  /// Offset - Distance from the beginning of the function to the beginning
213  /// of this basic block.
214  ///
215  /// Offsets are computed assuming worst case padding before an aligned
216  /// block. This means that subtracting basic block offsets always gives a
217  /// conservative estimate of the real distance which may be smaller.
218  ///
219  /// Because worst case padding is used, the computed offset of an aligned
220  /// block may not actually be aligned.
221  unsigned Offset;
222 
223  /// Size - Size of the basic block in bytes. If the block contains
224  /// inline assembly, this is a worst case estimate.
225  ///
226  /// The size does not include any alignment padding whether from the
227  /// beginning of the block, or from an aligned jump table at the end.
228  unsigned Size;
229 
230  // FIXME: ignore LogAlign for this patch
231  //
232  unsigned postOffset(unsigned LogAlign = 0) const {
233  unsigned PO = Offset + Size;
234  return PO;
235  }
236 
237  BasicBlockInfo() : Offset(0), Size(0) {}
238 
239  };
240 
241  std::vector<BasicBlockInfo> BBInfo;
242 
243  /// WaterList - A sorted list of basic blocks where islands could be placed
244  /// (i.e. blocks that don't fall through to the following block, due
245  /// to a return, unreachable, or unconditional branch).
246  std::vector<MachineBasicBlock*> WaterList;
247 
248  /// NewWaterList - The subset of WaterList that was created since the
249  /// previous iteration by inserting unconditional branches.
250  SmallSet<MachineBasicBlock*, 4> NewWaterList;
251 
252  typedef std::vector<MachineBasicBlock*>::iterator water_iterator;
253 
254  /// CPUser - One user of a constant pool, keeping the machine instruction
255  /// pointer, the constant pool being referenced, and the max displacement
256  /// allowed from the instruction to the CP. The HighWaterMark records the
257  /// highest basic block where a new CPEntry can be placed. To ensure this
258  /// pass terminates, the CP entries are initially placed at the end of the
259  /// function and then move monotonically to lower addresses. The
260  /// exception to this rule is when the current CP entry for a particular
261  /// CPUser is out of range, but there is another CP entry for the same
262  /// constant value in range. We want to use the existing in-range CP
263  /// entry, but if it later moves out of range, the search for new water
264  /// should resume where it left off. The HighWaterMark is used to record
265  /// that point.
266  struct CPUser {
267  MachineInstr *MI;
268  MachineInstr *CPEMI;
269  MachineBasicBlock *HighWaterMark;
270  private:
271  unsigned MaxDisp;
272  unsigned LongFormMaxDisp; // mips16 has 16/32 bit instructions
273  // with different displacements
274  unsigned LongFormOpcode;
275  public:
276  bool NegOk;
277  CPUser(MachineInstr *mi, MachineInstr *cpemi, unsigned maxdisp,
278  bool neg,
279  unsigned longformmaxdisp, unsigned longformopcode)
280  : MI(mi), CPEMI(cpemi), MaxDisp(maxdisp),
281  LongFormMaxDisp(longformmaxdisp), LongFormOpcode(longformopcode),
282  NegOk(neg){
283  HighWaterMark = CPEMI->getParent();
284  }
285  /// getMaxDisp - Returns the maximum displacement supported by MI.
286  unsigned getMaxDisp() const {
287  unsigned xMaxDisp = ConstantIslandsSmallOffset?
289  return xMaxDisp;
290  }
291  void setMaxDisp(unsigned val) {
292  MaxDisp = val;
293  }
294  unsigned getLongFormMaxDisp() const {
295  return LongFormMaxDisp;
296  }
297  unsigned getLongFormOpcode() const {
298  return LongFormOpcode;
299  }
300  };
301 
302  /// CPUsers - Keep track of all of the machine instructions that use various
303  /// constant pools and their max displacement.
304  std::vector<CPUser> CPUsers;
305 
306  /// CPEntry - One per constant pool entry, keeping the machine instruction
307  /// pointer, the constpool index, and the number of CPUser's which
308  /// reference this entry.
309  struct CPEntry {
310  MachineInstr *CPEMI;
311  unsigned CPI;
312  unsigned RefCount;
313  CPEntry(MachineInstr *cpemi, unsigned cpi, unsigned rc = 0)
314  : CPEMI(cpemi), CPI(cpi), RefCount(rc) {}
315  };
316 
317  /// CPEntries - Keep track of all of the constant pool entry machine
318  /// instructions. For each original constpool index (i.e. those that
319  /// existed upon entry to this pass), it keeps a vector of entries.
320  /// Original elements are cloned as we go along; the clones are
321  /// put in the vector of the original element, but have distinct CPIs.
322  std::vector<std::vector<CPEntry> > CPEntries;
323 
324  /// ImmBranch - One per immediate branch, keeping the machine instruction
325  /// pointer, conditional or unconditional, the max displacement,
326  /// and (if isCond is true) the corresponding unconditional branch
327  /// opcode.
328  struct ImmBranch {
329  MachineInstr *MI;
330  unsigned MaxDisp : 31;
331  bool isCond : 1;
332  int UncondBr;
333  ImmBranch(MachineInstr *mi, unsigned maxdisp, bool cond, int ubr)
334  : MI(mi), MaxDisp(maxdisp), isCond(cond), UncondBr(ubr) {}
335  };
336 
337  /// ImmBranches - Keep track of all the immediate branch instructions.
338  ///
339  std::vector<ImmBranch> ImmBranches;
340 
341  /// HasFarJump - True if any far jump instruction has been emitted during
342  /// the branch fix up pass.
343  bool HasFarJump;
344 
345  const TargetMachine &TM;
346  bool IsPIC;
347  const MipsSubtarget *STI;
348  const Mips16InstrInfo *TII;
349  MipsFunctionInfo *MFI;
350  MachineFunction *MF;
351  MachineConstantPool *MCP;
352 
353  unsigned PICLabelUId;
354  bool PrescannedForConstants;
355 
356  void initPICLabelUId(unsigned UId) {
357  PICLabelUId = UId;
358  }
359 
360 
361  unsigned createPICLabelUId() {
362  return PICLabelUId++;
363  }
364 
365  public:
366  static char ID;
367  MipsConstantIslands(TargetMachine &tm)
368  : MachineFunctionPass(ID), TM(tm),
369  IsPIC(TM.getRelocationModel() == Reloc::PIC_), STI(nullptr),
370  MF(nullptr), MCP(nullptr), PrescannedForConstants(false) {}
371 
372  const char *getPassName() const override {
373  return "Mips Constant Islands";
374  }
375 
376  bool runOnMachineFunction(MachineFunction &F) override;
377 
378  void doInitialPlacement(std::vector<MachineInstr*> &CPEMIs);
379  CPEntry *findConstPoolEntry(unsigned CPI, const MachineInstr *CPEMI);
380  unsigned getCPELogAlign(const MachineInstr *CPEMI);
381  void initializeFunctionInfo(const std::vector<MachineInstr*> &CPEMIs);
382  unsigned getOffsetOf(MachineInstr *MI) const;
383  unsigned getUserOffset(CPUser&) const;
384  void dumpBBs();
385 
386  bool isOffsetInRange(unsigned UserOffset, unsigned TrialOffset,
387  unsigned Disp, bool NegativeOK);
388  bool isOffsetInRange(unsigned UserOffset, unsigned TrialOffset,
389  const CPUser &U);
390 
391  void computeBlockSize(MachineBasicBlock *MBB);
392  MachineBasicBlock *splitBlockBeforeInstr(MachineInstr *MI);
393  void updateForInsertedWaterBlock(MachineBasicBlock *NewBB);
394  void adjustBBOffsetsAfter(MachineBasicBlock *BB);
395  bool decrementCPEReferenceCount(unsigned CPI, MachineInstr* CPEMI);
396  int findInRangeCPEntry(CPUser& U, unsigned UserOffset);
397  int findLongFormInRangeCPEntry(CPUser& U, unsigned UserOffset);
398  bool findAvailableWater(CPUser&U, unsigned UserOffset,
399  water_iterator &WaterIter);
400  void createNewWater(unsigned CPUserIndex, unsigned UserOffset,
401  MachineBasicBlock *&NewMBB);
402  bool handleConstantPoolUser(unsigned CPUserIndex);
403  void removeDeadCPEMI(MachineInstr *CPEMI);
404  bool removeUnusedCPEntries();
405  bool isCPEntryInRange(MachineInstr *MI, unsigned UserOffset,
406  MachineInstr *CPEMI, unsigned Disp, bool NegOk,
407  bool DoDump = false);
408  bool isWaterInRange(unsigned UserOffset, MachineBasicBlock *Water,
409  CPUser &U, unsigned &Growth);
410  bool isBBInRange(MachineInstr *MI, MachineBasicBlock *BB, unsigned Disp);
411  bool fixupImmediateBr(ImmBranch &Br);
412  bool fixupConditionalBr(ImmBranch &Br);
413  bool fixupUnconditionalBr(ImmBranch &Br);
414 
415  void prescanForConstants();
416 
417  private:
418 
419  };
420 
421  char MipsConstantIslands::ID = 0;
422 } // end of anonymous namespace
423 
424 bool MipsConstantIslands::isOffsetInRange
425  (unsigned UserOffset, unsigned TrialOffset,
426  const CPUser &U) {
427  return isOffsetInRange(UserOffset, TrialOffset,
428  U.getMaxDisp(), U.NegOk);
429 }
430 /// print block size and offset information - debugging
431 void MipsConstantIslands::dumpBBs() {
432  DEBUG({
433  for (unsigned J = 0, E = BBInfo.size(); J !=E; ++J) {
434  const BasicBlockInfo &BBI = BBInfo[J];
435  dbgs() << format("%08x BB#%u\t", BBI.Offset, J)
436  << format(" size=%#x\n", BBInfo[J].Size);
437  }
438  });
439 }
440 /// createMipsLongBranchPass - Returns a pass that converts branches to long
441 /// branches.
443  return new MipsConstantIslands(tm);
444 }
445 
446 bool MipsConstantIslands::runOnMachineFunction(MachineFunction &mf) {
447  // The intention is for this to be a mips16 only pass for now
448  // FIXME:
449  MF = &mf;
450  MCP = mf.getConstantPool();
451  STI = &static_cast<const MipsSubtarget &>(mf.getSubtarget());
452  DEBUG(dbgs() << "constant island machine function " << "\n");
453  if (!STI->inMips16Mode() || !MipsSubtarget::useConstantIslands()) {
454  return false;
455  }
456  TII = (const Mips16InstrInfo *)STI->getInstrInfo();
457  MFI = MF->getInfo<MipsFunctionInfo>();
458  DEBUG(dbgs() << "constant island processing " << "\n");
459  //
460  // will need to make predermination if there is any constants we need to
461  // put in constant islands. TBD.
462  //
463  if (!PrescannedForConstants) prescanForConstants();
464 
465  HasFarJump = false;
466  // This pass invalidates liveness information when it splits basic blocks.
467  MF->getRegInfo().invalidateLiveness();
468 
469  // Renumber all of the machine basic blocks in the function, guaranteeing that
470  // the numbers agree with the position of the block in the function.
471  MF->RenumberBlocks();
472 
473  bool MadeChange = false;
474 
475  // Perform the initial placement of the constant pool entries. To start with,
476  // we put them all at the end of the function.
477  std::vector<MachineInstr*> CPEMIs;
478  if (!MCP->isEmpty())
479  doInitialPlacement(CPEMIs);
480 
481  /// The next UID to take is the first unused one.
482  initPICLabelUId(CPEMIs.size());
483 
484  // Do the initial scan of the function, building up information about the
485  // sizes of each block, the location of all the water, and finding all of the
486  // constant pool users.
487  initializeFunctionInfo(CPEMIs);
488  CPEMIs.clear();
489  DEBUG(dumpBBs());
490 
491  /// Remove dead constant pool entries.
492  MadeChange |= removeUnusedCPEntries();
493 
494  // Iteratively place constant pool entries and fix up branches until there
495  // is no change.
496  unsigned NoCPIters = 0, NoBRIters = 0;
497  (void)NoBRIters;
498  while (true) {
499  DEBUG(dbgs() << "Beginning CP iteration #" << NoCPIters << '\n');
500  bool CPChange = false;
501  for (unsigned i = 0, e = CPUsers.size(); i != e; ++i)
502  CPChange |= handleConstantPoolUser(i);
503  if (CPChange && ++NoCPIters > 30)
504  report_fatal_error("Constant Island pass failed to converge!");
505  DEBUG(dumpBBs());
506 
507  // Clear NewWaterList now. If we split a block for branches, it should
508  // appear as "new water" for the next iteration of constant pool placement.
509  NewWaterList.clear();
510 
511  DEBUG(dbgs() << "Beginning BR iteration #" << NoBRIters << '\n');
512  bool BRChange = false;
513  for (unsigned i = 0, e = ImmBranches.size(); i != e; ++i)
514  BRChange |= fixupImmediateBr(ImmBranches[i]);
515  if (BRChange && ++NoBRIters > 30)
516  report_fatal_error("Branch Fix Up pass failed to converge!");
517  DEBUG(dumpBBs());
518  if (!CPChange && !BRChange)
519  break;
520  MadeChange = true;
521  }
522 
523  DEBUG(dbgs() << '\n'; dumpBBs());
524 
525  BBInfo.clear();
526  WaterList.clear();
527  CPUsers.clear();
528  CPEntries.clear();
529  ImmBranches.clear();
530  return MadeChange;
531 }
532 
533 /// doInitialPlacement - Perform the initial placement of the constant pool
534 /// entries. To start with, we put them all at the end of the function.
535 void
536 MipsConstantIslands::doInitialPlacement(std::vector<MachineInstr*> &CPEMIs) {
537  // Create the basic block to hold the CPE's.
538  MachineBasicBlock *BB = MF->CreateMachineBasicBlock();
539  MF->push_back(BB);
540 
541 
542  // MachineConstantPool measures alignment in bytes. We measure in log2(bytes).
543  unsigned MaxAlign = Log2_32(MCP->getConstantPoolAlignment());
544 
545  // Mark the basic block as required by the const-pool.
546  // If AlignConstantIslands isn't set, use 4-byte alignment for everything.
547  BB->setAlignment(AlignConstantIslands ? MaxAlign : 2);
548 
549  // The function needs to be as aligned as the basic blocks. The linker may
550  // move functions around based on their alignment.
551  MF->ensureAlignment(BB->getAlignment());
552 
553  // Order the entries in BB by descending alignment. That ensures correct
554  // alignment of all entries as long as BB is sufficiently aligned. Keep
555  // track of the insertion point for each alignment. We are going to bucket
556  // sort the entries as they are created.
557  SmallVector<MachineBasicBlock::iterator, 8> InsPoint(MaxAlign + 1, BB->end());
558 
559  // Add all of the constants from the constant pool to the end block, use an
560  // identity mapping of CPI's to CPE's.
561  const std::vector<MachineConstantPoolEntry> &CPs = MCP->getConstants();
562 
563  const DataLayout &TD = *MF->getTarget().getDataLayout();
564  for (unsigned i = 0, e = CPs.size(); i != e; ++i) {
565  unsigned Size = TD.getTypeAllocSize(CPs[i].getType());
566  assert(Size >= 4 && "Too small constant pool entry");
567  unsigned Align = CPs[i].getAlignment();
568  assert(isPowerOf2_32(Align) && "Invalid alignment");
569  // Verify that all constant pool entries are a multiple of their alignment.
570  // If not, we would have to pad them out so that instructions stay aligned.
571  assert((Size % Align) == 0 && "CP Entry not multiple of 4 bytes!");
572 
573  // Insert CONSTPOOL_ENTRY before entries with a smaller alignment.
574  unsigned LogAlign = Log2_32(Align);
575  MachineBasicBlock::iterator InsAt = InsPoint[LogAlign];
576 
577  MachineInstr *CPEMI =
578  BuildMI(*BB, InsAt, DebugLoc(), TII->get(Mips::CONSTPOOL_ENTRY))
579  .addImm(i).addConstantPoolIndex(i).addImm(Size);
580 
581  CPEMIs.push_back(CPEMI);
582 
583  // Ensure that future entries with higher alignment get inserted before
584  // CPEMI. This is bucket sort with iterators.
585  for (unsigned a = LogAlign + 1; a <= MaxAlign; ++a)
586  if (InsPoint[a] == InsAt)
587  InsPoint[a] = CPEMI;
588  // Add a new CPEntry, but no corresponding CPUser yet.
589  CPEntries.emplace_back(1, CPEntry(CPEMI, i));
590  ++NumCPEs;
591  DEBUG(dbgs() << "Moved CPI#" << i << " to end of function, size = "
592  << Size << ", align = " << Align <<'\n');
593  }
594  DEBUG(BB->dump());
595 }
596 
597 /// BBHasFallthrough - Return true if the specified basic block can fallthrough
598 /// into the block immediately after it.
600  // Get the next machine basic block in the function.
601  MachineFunction::iterator MBBI = MBB;
602  // Can't fall off end of function.
603  if (std::next(MBBI) == MBB->getParent()->end())
604  return false;
605 
606  MachineBasicBlock *NextBB = std::next(MBBI);
608  E = MBB->succ_end(); I != E; ++I)
609  if (*I == NextBB)
610  return true;
611 
612  return false;
613 }
614 
615 /// findConstPoolEntry - Given the constpool index and CONSTPOOL_ENTRY MI,
616 /// look up the corresponding CPEntry.
617 MipsConstantIslands::CPEntry
618 *MipsConstantIslands::findConstPoolEntry(unsigned CPI,
619  const MachineInstr *CPEMI) {
620  std::vector<CPEntry> &CPEs = CPEntries[CPI];
621  // Number of entries per constpool index should be small, just do a
622  // linear search.
623  for (unsigned i = 0, e = CPEs.size(); i != e; ++i) {
624  if (CPEs[i].CPEMI == CPEMI)
625  return &CPEs[i];
626  }
627  return nullptr;
628 }
629 
630 /// getCPELogAlign - Returns the required alignment of the constant pool entry
631 /// represented by CPEMI. Alignment is measured in log2(bytes) units.
632 unsigned MipsConstantIslands::getCPELogAlign(const MachineInstr *CPEMI) {
633  assert(CPEMI && CPEMI->getOpcode() == Mips::CONSTPOOL_ENTRY);
634 
635  // Everything is 4-byte aligned unless AlignConstantIslands is set.
637  return 2;
638 
639  unsigned CPI = CPEMI->getOperand(1).getIndex();
640  assert(CPI < MCP->getConstants().size() && "Invalid constant pool index.");
641  unsigned Align = MCP->getConstants()[CPI].getAlignment();
642  assert(isPowerOf2_32(Align) && "Invalid CPE alignment");
643  return Log2_32(Align);
644 }
645 
646 /// initializeFunctionInfo - Do the initial scan of the function, building up
647 /// information about the sizes of each block, the location of all the water,
648 /// and finding all of the constant pool users.
649 void MipsConstantIslands::
650 initializeFunctionInfo(const std::vector<MachineInstr*> &CPEMIs) {
651  BBInfo.clear();
652  BBInfo.resize(MF->getNumBlockIDs());
653 
654  // First thing, compute the size of all basic blocks, and see if the function
655  // has any inline assembly in it. If so, we have to be conservative about
656  // alignment assumptions, as we don't know for sure the size of any
657  // instructions in the inline assembly.
658  for (MachineFunction::iterator I = MF->begin(), E = MF->end(); I != E; ++I)
659  computeBlockSize(I);
660 
661 
662  // Compute block offsets.
663  adjustBBOffsetsAfter(MF->begin());
664 
665  // Now go back through the instructions and build up our data structures.
666  for (MachineFunction::iterator MBBI = MF->begin(), E = MF->end();
667  MBBI != E; ++MBBI) {
668  MachineBasicBlock &MBB = *MBBI;
669 
670  // If this block doesn't fall through into the next MBB, then this is
671  // 'water' that a constant pool island could be placed.
672  if (!BBHasFallthrough(&MBB))
673  WaterList.push_back(&MBB);
674  for (MachineBasicBlock::iterator I = MBB.begin(), E = MBB.end();
675  I != E; ++I) {
676  if (I->isDebugValue())
677  continue;
678 
679  int Opc = I->getOpcode();
680  if (I->isBranch()) {
681  bool isCond = false;
682  unsigned Bits = 0;
683  unsigned Scale = 1;
684  int UOpc = Opc;
685  switch (Opc) {
686  default:
687  continue; // Ignore other branches for now
688  case Mips::Bimm16:
689  Bits = 11;
690  Scale = 2;
691  isCond = false;
692  break;
693  case Mips::BimmX16:
694  Bits = 16;
695  Scale = 2;
696  isCond = false;
697  break;
698  case Mips::BeqzRxImm16:
699  UOpc=Mips::Bimm16;
700  Bits = 8;
701  Scale = 2;
702  isCond = true;
703  break;
704  case Mips::BeqzRxImmX16:
705  UOpc=Mips::Bimm16;
706  Bits = 16;
707  Scale = 2;
708  isCond = true;
709  break;
710  case Mips::BnezRxImm16:
711  UOpc=Mips::Bimm16;
712  Bits = 8;
713  Scale = 2;
714  isCond = true;
715  break;
716  case Mips::BnezRxImmX16:
717  UOpc=Mips::Bimm16;
718  Bits = 16;
719  Scale = 2;
720  isCond = true;
721  break;
722  case Mips::Bteqz16:
723  UOpc=Mips::Bimm16;
724  Bits = 8;
725  Scale = 2;
726  isCond = true;
727  break;
728  case Mips::BteqzX16:
729  UOpc=Mips::Bimm16;
730  Bits = 16;
731  Scale = 2;
732  isCond = true;
733  break;
734  case Mips::Btnez16:
735  UOpc=Mips::Bimm16;
736  Bits = 8;
737  Scale = 2;
738  isCond = true;
739  break;
740  case Mips::BtnezX16:
741  UOpc=Mips::Bimm16;
742  Bits = 16;
743  Scale = 2;
744  isCond = true;
745  break;
746  }
747  // Record this immediate branch.
748  unsigned MaxOffs = ((1 << (Bits-1))-1) * Scale;
749  ImmBranches.push_back(ImmBranch(I, MaxOffs, isCond, UOpc));
750  }
751 
752  if (Opc == Mips::CONSTPOOL_ENTRY)
753  continue;
754 
755 
756  // Scan the instructions for constant pool operands.
757  for (unsigned op = 0, e = I->getNumOperands(); op != e; ++op)
758  if (I->getOperand(op).isCPI()) {
759 
760  // We found one. The addressing mode tells us the max displacement
761  // from the PC that this instruction permits.
762 
763  // Basic size info comes from the TSFlags field.
764  unsigned Bits = 0;
765  unsigned Scale = 1;
766  bool NegOk = false;
767  unsigned LongFormBits = 0;
768  unsigned LongFormScale = 0;
769  unsigned LongFormOpcode = 0;
770  switch (Opc) {
771  default:
772  llvm_unreachable("Unknown addressing mode for CP reference!");
773  case Mips::LwRxPcTcp16:
774  Bits = 8;
775  Scale = 4;
776  LongFormOpcode = Mips::LwRxPcTcpX16;
777  LongFormBits = 14;
778  LongFormScale = 1;
779  break;
780  case Mips::LwRxPcTcpX16:
781  Bits = 14;
782  Scale = 1;
783  NegOk = true;
784  break;
785  }
786  // Remember that this is a user of a CP entry.
787  unsigned CPI = I->getOperand(op).getIndex();
788  MachineInstr *CPEMI = CPEMIs[CPI];
789  unsigned MaxOffs = ((1 << Bits)-1) * Scale;
790  unsigned LongFormMaxOffs = ((1 << LongFormBits)-1) * LongFormScale;
791  CPUsers.push_back(CPUser(I, CPEMI, MaxOffs, NegOk,
792  LongFormMaxOffs, LongFormOpcode));
793 
794  // Increment corresponding CPEntry reference count.
795  CPEntry *CPE = findConstPoolEntry(CPI, CPEMI);
796  assert(CPE && "Cannot find a corresponding CPEntry!");
797  CPE->RefCount++;
798 
799  // Instructions can only use one CP entry, don't bother scanning the
800  // rest of the operands.
801  break;
802 
803  }
804 
805  }
806  }
807 
808 }
809 
810 /// computeBlockSize - Compute the size and some alignment information for MBB.
811 /// This function updates BBInfo directly.
812 void MipsConstantIslands::computeBlockSize(MachineBasicBlock *MBB) {
813  BasicBlockInfo &BBI = BBInfo[MBB->getNumber()];
814  BBI.Size = 0;
815 
816  for (MachineBasicBlock::iterator I = MBB->begin(), E = MBB->end(); I != E;
817  ++I)
818  BBI.Size += TII->GetInstSizeInBytes(I);
819 
820 }
821 
822 /// getOffsetOf - Return the current offset of the specified machine instruction
823 /// from the start of the function. This offset changes as stuff is moved
824 /// around inside the function.
825 unsigned MipsConstantIslands::getOffsetOf(MachineInstr *MI) const {
826  MachineBasicBlock *MBB = MI->getParent();
827 
828  // The offset is composed of two things: the sum of the sizes of all MBB's
829  // before this instruction's block, and the offset from the start of the block
830  // it is in.
831  unsigned Offset = BBInfo[MBB->getNumber()].Offset;
832 
833  // Sum instructions before MI in MBB.
834  for (MachineBasicBlock::iterator I = MBB->begin(); &*I != MI; ++I) {
835  assert(I != MBB->end() && "Didn't find MI in its own basic block?");
836  Offset += TII->GetInstSizeInBytes(I);
837  }
838  return Offset;
839 }
840 
841 /// CompareMBBNumbers - Little predicate function to sort the WaterList by MBB
842 /// ID.
843 static bool CompareMBBNumbers(const MachineBasicBlock *LHS,
844  const MachineBasicBlock *RHS) {
845  return LHS->getNumber() < RHS->getNumber();
846 }
847 
848 /// updateForInsertedWaterBlock - When a block is newly inserted into the
849 /// machine function, it upsets all of the block numbers. Renumber the blocks
850 /// and update the arrays that parallel this numbering.
851 void MipsConstantIslands::updateForInsertedWaterBlock
852  (MachineBasicBlock *NewBB) {
853  // Renumber the MBB's to keep them consecutive.
854  NewBB->getParent()->RenumberBlocks(NewBB);
855 
856  // Insert an entry into BBInfo to align it properly with the (newly
857  // renumbered) block numbers.
858  BBInfo.insert(BBInfo.begin() + NewBB->getNumber(), BasicBlockInfo());
859 
860  // Next, update WaterList. Specifically, we need to add NewMBB as having
861  // available water after it.
862  water_iterator IP =
863  std::lower_bound(WaterList.begin(), WaterList.end(), NewBB,
865  WaterList.insert(IP, NewBB);
866 }
867 
868 unsigned MipsConstantIslands::getUserOffset(CPUser &U) const {
869  return getOffsetOf(U.MI);
870 }
871 
872 /// Split the basic block containing MI into two blocks, which are joined by
873 /// an unconditional branch. Update data structures and renumber blocks to
874 /// account for this change and returns the newly created block.
875 MachineBasicBlock *MipsConstantIslands::splitBlockBeforeInstr
876  (MachineInstr *MI) {
877  MachineBasicBlock *OrigBB = MI->getParent();
878 
879  // Create a new MBB for the code after the OrigBB.
880  MachineBasicBlock *NewBB =
881  MF->CreateMachineBasicBlock(OrigBB->getBasicBlock());
882  MachineFunction::iterator MBBI = OrigBB; ++MBBI;
883  MF->insert(MBBI, NewBB);
884 
885  // Splice the instructions starting with MI over to NewBB.
886  NewBB->splice(NewBB->end(), OrigBB, MI, OrigBB->end());
887 
888  // Add an unconditional branch from OrigBB to NewBB.
889  // Note the new unconditional branch is not being recorded.
890  // There doesn't seem to be meaningful DebugInfo available; this doesn't
891  // correspond to anything in the source.
892  BuildMI(OrigBB, DebugLoc(), TII->get(Mips::Bimm16)).addMBB(NewBB);
893  ++NumSplit;
894 
895  // Update the CFG. All succs of OrigBB are now succs of NewBB.
896  NewBB->transferSuccessors(OrigBB);
897 
898  // OrigBB branches to NewBB.
899  OrigBB->addSuccessor(NewBB);
900 
901  // Update internal data structures to account for the newly inserted MBB.
902  // This is almost the same as updateForInsertedWaterBlock, except that
903  // the Water goes after OrigBB, not NewBB.
904  MF->RenumberBlocks(NewBB);
905 
906  // Insert an entry into BBInfo to align it properly with the (newly
907  // renumbered) block numbers.
908  BBInfo.insert(BBInfo.begin() + NewBB->getNumber(), BasicBlockInfo());
909 
910  // Next, update WaterList. Specifically, we need to add OrigMBB as having
911  // available water after it (but not if it's already there, which happens
912  // when splitting before a conditional branch that is followed by an
913  // unconditional branch - in that case we want to insert NewBB).
914  water_iterator IP =
915  std::lower_bound(WaterList.begin(), WaterList.end(), OrigBB,
917  MachineBasicBlock* WaterBB = *IP;
918  if (WaterBB == OrigBB)
919  WaterList.insert(std::next(IP), NewBB);
920  else
921  WaterList.insert(IP, OrigBB);
922  NewWaterList.insert(OrigBB);
923 
924  // Figure out how large the OrigBB is. As the first half of the original
925  // block, it cannot contain a tablejump. The size includes
926  // the new jump we added. (It should be possible to do this without
927  // recounting everything, but it's very confusing, and this is rarely
928  // executed.)
929  computeBlockSize(OrigBB);
930 
931  // Figure out how large the NewMBB is. As the second half of the original
932  // block, it may contain a tablejump.
933  computeBlockSize(NewBB);
934 
935  // All BBOffsets following these blocks must be modified.
936  adjustBBOffsetsAfter(OrigBB);
937 
938  return NewBB;
939 }
940 
941 
942 
943 /// isOffsetInRange - Checks whether UserOffset (the location of a constant pool
944 /// reference) is within MaxDisp of TrialOffset (a proposed location of a
945 /// constant pool entry).
946 bool MipsConstantIslands::isOffsetInRange(unsigned UserOffset,
947  unsigned TrialOffset, unsigned MaxDisp,
948  bool NegativeOK) {
949  if (UserOffset <= TrialOffset) {
950  // User before the Trial.
951  if (TrialOffset - UserOffset <= MaxDisp)
952  return true;
953  } else if (NegativeOK) {
954  if (UserOffset - TrialOffset <= MaxDisp)
955  return true;
956  }
957  return false;
958 }
959 
960 /// isWaterInRange - Returns true if a CPE placed after the specified
961 /// Water (a basic block) will be in range for the specific MI.
962 ///
963 /// Compute how much the function will grow by inserting a CPE after Water.
964 bool MipsConstantIslands::isWaterInRange(unsigned UserOffset,
965  MachineBasicBlock* Water, CPUser &U,
966  unsigned &Growth) {
967  unsigned CPELogAlign = getCPELogAlign(U.CPEMI);
968  unsigned CPEOffset = BBInfo[Water->getNumber()].postOffset(CPELogAlign);
969  unsigned NextBlockOffset, NextBlockAlignment;
970  MachineFunction::const_iterator NextBlock = Water;
971  if (++NextBlock == MF->end()) {
972  NextBlockOffset = BBInfo[Water->getNumber()].postOffset();
973  NextBlockAlignment = 0;
974  } else {
975  NextBlockOffset = BBInfo[NextBlock->getNumber()].Offset;
976  NextBlockAlignment = NextBlock->getAlignment();
977  }
978  unsigned Size = U.CPEMI->getOperand(2).getImm();
979  unsigned CPEEnd = CPEOffset + Size;
980 
981  // The CPE may be able to hide in the alignment padding before the next
982  // block. It may also cause more padding to be required if it is more aligned
983  // that the next block.
984  if (CPEEnd > NextBlockOffset) {
985  Growth = CPEEnd - NextBlockOffset;
986  // Compute the padding that would go at the end of the CPE to align the next
987  // block.
988  Growth += OffsetToAlignment(CPEEnd, 1u << NextBlockAlignment);
989 
990  // If the CPE is to be inserted before the instruction, that will raise
991  // the offset of the instruction. Also account for unknown alignment padding
992  // in blocks between CPE and the user.
993  if (CPEOffset < UserOffset)
994  UserOffset += Growth;
995  } else
996  // CPE fits in existing padding.
997  Growth = 0;
998 
999  return isOffsetInRange(UserOffset, CPEOffset, U);
1000 }
1001 
1002 /// isCPEntryInRange - Returns true if the distance between specific MI and
1003 /// specific ConstPool entry instruction can fit in MI's displacement field.
1004 bool MipsConstantIslands::isCPEntryInRange
1005  (MachineInstr *MI, unsigned UserOffset,
1006  MachineInstr *CPEMI, unsigned MaxDisp,
1007  bool NegOk, bool DoDump) {
1008  unsigned CPEOffset = getOffsetOf(CPEMI);
1009 
1010  if (DoDump) {
1011  DEBUG({
1012  unsigned Block = MI->getParent()->getNumber();
1013  const BasicBlockInfo &BBI = BBInfo[Block];
1014  dbgs() << "User of CPE#" << CPEMI->getOperand(0).getImm()
1015  << " max delta=" << MaxDisp
1016  << format(" insn address=%#x", UserOffset)
1017  << " in BB#" << Block << ": "
1018  << format("%#x-%x\t", BBI.Offset, BBI.postOffset()) << *MI
1019  << format("CPE address=%#x offset=%+d: ", CPEOffset,
1020  int(CPEOffset-UserOffset));
1021  });
1022  }
1023 
1024  return isOffsetInRange(UserOffset, CPEOffset, MaxDisp, NegOk);
1025 }
1026 
1027 #ifndef NDEBUG
1028 /// BBIsJumpedOver - Return true of the specified basic block's only predecessor
1029 /// unconditionally branches to its only successor.
1031  if (MBB->pred_size() != 1 || MBB->succ_size() != 1)
1032  return false;
1033  MachineBasicBlock *Succ = *MBB->succ_begin();
1034  MachineBasicBlock *Pred = *MBB->pred_begin();
1035  MachineInstr *PredMI = &Pred->back();
1036  if (PredMI->getOpcode() == Mips::Bimm16)
1037  return PredMI->getOperand(0).getMBB() == Succ;
1038  return false;
1039 }
1040 #endif
1041 
1042 void MipsConstantIslands::adjustBBOffsetsAfter(MachineBasicBlock *BB) {
1043  unsigned BBNum = BB->getNumber();
1044  for(unsigned i = BBNum + 1, e = MF->getNumBlockIDs(); i < e; ++i) {
1045  // Get the offset and known bits at the end of the layout predecessor.
1046  // Include the alignment of the current block.
1047  unsigned Offset = BBInfo[i - 1].Offset + BBInfo[i - 1].Size;
1048  BBInfo[i].Offset = Offset;
1049  }
1050 }
1051 
1052 /// decrementCPEReferenceCount - find the constant pool entry with index CPI
1053 /// and instruction CPEMI, and decrement its refcount. If the refcount
1054 /// becomes 0 remove the entry and instruction. Returns true if we removed
1055 /// the entry, false if we didn't.
1056 
1057 bool MipsConstantIslands::decrementCPEReferenceCount(unsigned CPI,
1058  MachineInstr *CPEMI) {
1059  // Find the old entry. Eliminate it if it is no longer used.
1060  CPEntry *CPE = findConstPoolEntry(CPI, CPEMI);
1061  assert(CPE && "Unexpected!");
1062  if (--CPE->RefCount == 0) {
1063  removeDeadCPEMI(CPEMI);
1064  CPE->CPEMI = nullptr;
1065  --NumCPEs;
1066  return true;
1067  }
1068  return false;
1069 }
1070 
1071 /// LookForCPEntryInRange - see if the currently referenced CPE is in range;
1072 /// if not, see if an in-range clone of the CPE is in range, and if so,
1073 /// change the data structures so the user references the clone. Returns:
1074 /// 0 = no existing entry found
1075 /// 1 = entry found, and there were no code insertions or deletions
1076 /// 2 = entry found, and there were code insertions or deletions
1077 int MipsConstantIslands::findInRangeCPEntry(CPUser& U, unsigned UserOffset)
1078 {
1079  MachineInstr *UserMI = U.MI;
1080  MachineInstr *CPEMI = U.CPEMI;
1081 
1082  // Check to see if the CPE is already in-range.
1083  if (isCPEntryInRange(UserMI, UserOffset, CPEMI, U.getMaxDisp(), U.NegOk,
1084  true)) {
1085  DEBUG(dbgs() << "In range\n");
1086  return 1;
1087  }
1088 
1089  // No. Look for previously created clones of the CPE that are in range.
1090  unsigned CPI = CPEMI->getOperand(1).getIndex();
1091  std::vector<CPEntry> &CPEs = CPEntries[CPI];
1092  for (unsigned i = 0, e = CPEs.size(); i != e; ++i) {
1093  // We already tried this one
1094  if (CPEs[i].CPEMI == CPEMI)
1095  continue;
1096  // Removing CPEs can leave empty entries, skip
1097  if (CPEs[i].CPEMI == nullptr)
1098  continue;
1099  if (isCPEntryInRange(UserMI, UserOffset, CPEs[i].CPEMI, U.getMaxDisp(),
1100  U.NegOk)) {
1101  DEBUG(dbgs() << "Replacing CPE#" << CPI << " with CPE#"
1102  << CPEs[i].CPI << "\n");
1103  // Point the CPUser node to the replacement
1104  U.CPEMI = CPEs[i].CPEMI;
1105  // Change the CPI in the instruction operand to refer to the clone.
1106  for (unsigned j = 0, e = UserMI->getNumOperands(); j != e; ++j)
1107  if (UserMI->getOperand(j).isCPI()) {
1108  UserMI->getOperand(j).setIndex(CPEs[i].CPI);
1109  break;
1110  }
1111  // Adjust the refcount of the clone...
1112  CPEs[i].RefCount++;
1113  // ...and the original. If we didn't remove the old entry, none of the
1114  // addresses changed, so we don't need another pass.
1115  return decrementCPEReferenceCount(CPI, CPEMI) ? 2 : 1;
1116  }
1117  }
1118  return 0;
1119 }
1120 
1121 /// LookForCPEntryInRange - see if the currently referenced CPE is in range;
1122 /// This version checks if the longer form of the instruction can be used to
1123 /// to satisfy things.
1124 /// if not, see if an in-range clone of the CPE is in range, and if so,
1125 /// change the data structures so the user references the clone. Returns:
1126 /// 0 = no existing entry found
1127 /// 1 = entry found, and there were no code insertions or deletions
1128 /// 2 = entry found, and there were code insertions or deletions
1129 int MipsConstantIslands::findLongFormInRangeCPEntry
1130  (CPUser& U, unsigned UserOffset)
1131 {
1132  MachineInstr *UserMI = U.MI;
1133  MachineInstr *CPEMI = U.CPEMI;
1134 
1135  // Check to see if the CPE is already in-range.
1136  if (isCPEntryInRange(UserMI, UserOffset, CPEMI,
1137  U.getLongFormMaxDisp(), U.NegOk,
1138  true)) {
1139  DEBUG(dbgs() << "In range\n");
1140  UserMI->setDesc(TII->get(U.getLongFormOpcode()));
1141  U.setMaxDisp(U.getLongFormMaxDisp());
1142  return 2; // instruction is longer length now
1143  }
1144 
1145  // No. Look for previously created clones of the CPE that are in range.
1146  unsigned CPI = CPEMI->getOperand(1).getIndex();
1147  std::vector<CPEntry> &CPEs = CPEntries[CPI];
1148  for (unsigned i = 0, e = CPEs.size(); i != e; ++i) {
1149  // We already tried this one
1150  if (CPEs[i].CPEMI == CPEMI)
1151  continue;
1152  // Removing CPEs can leave empty entries, skip
1153  if (CPEs[i].CPEMI == nullptr)
1154  continue;
1155  if (isCPEntryInRange(UserMI, UserOffset, CPEs[i].CPEMI,
1156  U.getLongFormMaxDisp(), U.NegOk)) {
1157  DEBUG(dbgs() << "Replacing CPE#" << CPI << " with CPE#"
1158  << CPEs[i].CPI << "\n");
1159  // Point the CPUser node to the replacement
1160  U.CPEMI = CPEs[i].CPEMI;
1161  // Change the CPI in the instruction operand to refer to the clone.
1162  for (unsigned j = 0, e = UserMI->getNumOperands(); j != e; ++j)
1163  if (UserMI->getOperand(j).isCPI()) {
1164  UserMI->getOperand(j).setIndex(CPEs[i].CPI);
1165  break;
1166  }
1167  // Adjust the refcount of the clone...
1168  CPEs[i].RefCount++;
1169  // ...and the original. If we didn't remove the old entry, none of the
1170  // addresses changed, so we don't need another pass.
1171  return decrementCPEReferenceCount(CPI, CPEMI) ? 2 : 1;
1172  }
1173  }
1174  return 0;
1175 }
1176 
1177 /// getUnconditionalBrDisp - Returns the maximum displacement that can fit in
1178 /// the specific unconditional branch instruction.
1179 static inline unsigned getUnconditionalBrDisp(int Opc) {
1180  switch (Opc) {
1181  case Mips::Bimm16:
1182  return ((1<<10)-1)*2;
1183  case Mips::BimmX16:
1184  return ((1<<16)-1)*2;
1185  default:
1186  break;
1187  }
1188  return ((1<<16)-1)*2;
1189 }
1190 
1191 /// findAvailableWater - Look for an existing entry in the WaterList in which
1192 /// we can place the CPE referenced from U so it's within range of U's MI.
1193 /// Returns true if found, false if not. If it returns true, WaterIter
1194 /// is set to the WaterList entry.
1195 /// To ensure that this pass
1196 /// terminates, the CPE location for a particular CPUser is only allowed to
1197 /// move to a lower address, so search backward from the end of the list and
1198 /// prefer the first water that is in range.
1199 bool MipsConstantIslands::findAvailableWater(CPUser &U, unsigned UserOffset,
1200  water_iterator &WaterIter) {
1201  if (WaterList.empty())
1202  return false;
1203 
1204  unsigned BestGrowth = ~0u;
1205  for (water_iterator IP = std::prev(WaterList.end()), B = WaterList.begin();;
1206  --IP) {
1207  MachineBasicBlock* WaterBB = *IP;
1208  // Check if water is in range and is either at a lower address than the
1209  // current "high water mark" or a new water block that was created since
1210  // the previous iteration by inserting an unconditional branch. In the
1211  // latter case, we want to allow resetting the high water mark back to
1212  // this new water since we haven't seen it before. Inserting branches
1213  // should be relatively uncommon and when it does happen, we want to be
1214  // sure to take advantage of it for all the CPEs near that block, so that
1215  // we don't insert more branches than necessary.
1216  unsigned Growth;
1217  if (isWaterInRange(UserOffset, WaterBB, U, Growth) &&
1218  (WaterBB->getNumber() < U.HighWaterMark->getNumber() ||
1219  NewWaterList.count(WaterBB)) && Growth < BestGrowth) {
1220  // This is the least amount of required padding seen so far.
1221  BestGrowth = Growth;
1222  WaterIter = IP;
1223  DEBUG(dbgs() << "Found water after BB#" << WaterBB->getNumber()
1224  << " Growth=" << Growth << '\n');
1225 
1226  // Keep looking unless it is perfect.
1227  if (BestGrowth == 0)
1228  return true;
1229  }
1230  if (IP == B)
1231  break;
1232  }
1233  return BestGrowth != ~0u;
1234 }
1235 
1236 /// createNewWater - No existing WaterList entry will work for
1237 /// CPUsers[CPUserIndex], so create a place to put the CPE. The end of the
1238 /// block is used if in range, and the conditional branch munged so control
1239 /// flow is correct. Otherwise the block is split to create a hole with an
1240 /// unconditional branch around it. In either case NewMBB is set to a
1241 /// block following which the new island can be inserted (the WaterList
1242 /// is not adjusted).
1243 void MipsConstantIslands::createNewWater(unsigned CPUserIndex,
1244  unsigned UserOffset,
1245  MachineBasicBlock *&NewMBB) {
1246  CPUser &U = CPUsers[CPUserIndex];
1247  MachineInstr *UserMI = U.MI;
1248  MachineInstr *CPEMI = U.CPEMI;
1249  unsigned CPELogAlign = getCPELogAlign(CPEMI);
1250  MachineBasicBlock *UserMBB = UserMI->getParent();
1251  const BasicBlockInfo &UserBBI = BBInfo[UserMBB->getNumber()];
1252 
1253  // If the block does not end in an unconditional branch already, and if the
1254  // end of the block is within range, make new water there.
1255  if (BBHasFallthrough(UserMBB)) {
1256  // Size of branch to insert.
1257  unsigned Delta = 2;
1258  // Compute the offset where the CPE will begin.
1259  unsigned CPEOffset = UserBBI.postOffset(CPELogAlign) + Delta;
1260 
1261  if (isOffsetInRange(UserOffset, CPEOffset, U)) {
1262  DEBUG(dbgs() << "Split at end of BB#" << UserMBB->getNumber()
1263  << format(", expected CPE offset %#x\n", CPEOffset));
1264  NewMBB = std::next(MachineFunction::iterator(UserMBB));
1265  // Add an unconditional branch from UserMBB to fallthrough block. Record
1266  // it for branch lengthening; this new branch will not get out of range,
1267  // but if the preceding conditional branch is out of range, the targets
1268  // will be exchanged, and the altered branch may be out of range, so the
1269  // machinery has to know about it.
1270  int UncondBr = Mips::Bimm16;
1271  BuildMI(UserMBB, DebugLoc(), TII->get(UncondBr)).addMBB(NewMBB);
1272  unsigned MaxDisp = getUnconditionalBrDisp(UncondBr);
1273  ImmBranches.push_back(ImmBranch(&UserMBB->back(),
1274  MaxDisp, false, UncondBr));
1275  BBInfo[UserMBB->getNumber()].Size += Delta;
1276  adjustBBOffsetsAfter(UserMBB);
1277  return;
1278  }
1279  }
1280 
1281  // What a big block. Find a place within the block to split it.
1282 
1283  // Try to split the block so it's fully aligned. Compute the latest split
1284  // point where we can add a 4-byte branch instruction, and then align to
1285  // LogAlign which is the largest possible alignment in the function.
1286  unsigned LogAlign = MF->getAlignment();
1287  assert(LogAlign >= CPELogAlign && "Over-aligned constant pool entry");
1288  unsigned BaseInsertOffset = UserOffset + U.getMaxDisp();
1289  DEBUG(dbgs() << format("Split in middle of big block before %#x",
1290  BaseInsertOffset));
1291 
1292  // The 4 in the following is for the unconditional branch we'll be inserting
1293  // Alignment of the island is handled
1294  // inside isOffsetInRange.
1295  BaseInsertOffset -= 4;
1296 
1297  DEBUG(dbgs() << format(", adjusted to %#x", BaseInsertOffset)
1298  << " la=" << LogAlign << '\n');
1299 
1300  // This could point off the end of the block if we've already got constant
1301  // pool entries following this block; only the last one is in the water list.
1302  // Back past any possible branches (allow for a conditional and a maximally
1303  // long unconditional).
1304  if (BaseInsertOffset + 8 >= UserBBI.postOffset()) {
1305  BaseInsertOffset = UserBBI.postOffset() - 8;
1306  DEBUG(dbgs() << format("Move inside block: %#x\n", BaseInsertOffset));
1307  }
1308  unsigned EndInsertOffset = BaseInsertOffset + 4 +
1309  CPEMI->getOperand(2).getImm();
1310  MachineBasicBlock::iterator MI = UserMI;
1311  ++MI;
1312  unsigned CPUIndex = CPUserIndex+1;
1313  unsigned NumCPUsers = CPUsers.size();
1314  //MachineInstr *LastIT = 0;
1315  for (unsigned Offset = UserOffset+TII->GetInstSizeInBytes(UserMI);
1316  Offset < BaseInsertOffset;
1317  Offset += TII->GetInstSizeInBytes(MI), MI = std::next(MI)) {
1318  assert(MI != UserMBB->end() && "Fell off end of block");
1319  if (CPUIndex < NumCPUsers && CPUsers[CPUIndex].MI == MI) {
1320  CPUser &U = CPUsers[CPUIndex];
1321  if (!isOffsetInRange(Offset, EndInsertOffset, U)) {
1322  // Shift intertion point by one unit of alignment so it is within reach.
1323  BaseInsertOffset -= 1u << LogAlign;
1324  EndInsertOffset -= 1u << LogAlign;
1325  }
1326  // This is overly conservative, as we don't account for CPEMIs being
1327  // reused within the block, but it doesn't matter much. Also assume CPEs
1328  // are added in order with alignment padding. We may eventually be able
1329  // to pack the aligned CPEs better.
1330  EndInsertOffset += U.CPEMI->getOperand(2).getImm();
1331  CPUIndex++;
1332  }
1333  }
1334 
1335  --MI;
1336  NewMBB = splitBlockBeforeInstr(MI);
1337 }
1338 
1339 /// handleConstantPoolUser - Analyze the specified user, checking to see if it
1340 /// is out-of-range. If so, pick up the constant pool value and move it some
1341 /// place in-range. Return true if we changed any addresses (thus must run
1342 /// another pass of branch lengthening), false otherwise.
1343 bool MipsConstantIslands::handleConstantPoolUser(unsigned CPUserIndex) {
1344  CPUser &U = CPUsers[CPUserIndex];
1345  MachineInstr *UserMI = U.MI;
1346  MachineInstr *CPEMI = U.CPEMI;
1347  unsigned CPI = CPEMI->getOperand(1).getIndex();
1348  unsigned Size = CPEMI->getOperand(2).getImm();
1349  // Compute this only once, it's expensive.
1350  unsigned UserOffset = getUserOffset(U);
1351 
1352  // See if the current entry is within range, or there is a clone of it
1353  // in range.
1354  int result = findInRangeCPEntry(U, UserOffset);
1355  if (result==1) return false;
1356  else if (result==2) return true;
1357 
1358 
1359  // Look for water where we can place this CPE.
1360  MachineBasicBlock *NewIsland = MF->CreateMachineBasicBlock();
1361  MachineBasicBlock *NewMBB;
1362  water_iterator IP;
1363  if (findAvailableWater(U, UserOffset, IP)) {
1364  DEBUG(dbgs() << "Found water in range\n");
1365  MachineBasicBlock *WaterBB = *IP;
1366 
1367  // If the original WaterList entry was "new water" on this iteration,
1368  // propagate that to the new island. This is just keeping NewWaterList
1369  // updated to match the WaterList, which will be updated below.
1370  if (NewWaterList.erase(WaterBB))
1371  NewWaterList.insert(NewIsland);
1372 
1373  // The new CPE goes before the following block (NewMBB).
1374  NewMBB = std::next(MachineFunction::iterator(WaterBB));
1375 
1376  } else {
1377  // No water found.
1378  // we first see if a longer form of the instrucion could have reached
1379  // the constant. in that case we won't bother to split
1380  if (!NoLoadRelaxation) {
1381  result = findLongFormInRangeCPEntry(U, UserOffset);
1382  if (result != 0) return true;
1383  }
1384  DEBUG(dbgs() << "No water found\n");
1385  createNewWater(CPUserIndex, UserOffset, NewMBB);
1386 
1387  // splitBlockBeforeInstr adds to WaterList, which is important when it is
1388  // called while handling branches so that the water will be seen on the
1389  // next iteration for constant pools, but in this context, we don't want
1390  // it. Check for this so it will be removed from the WaterList.
1391  // Also remove any entry from NewWaterList.
1392  MachineBasicBlock *WaterBB = std::prev(MachineFunction::iterator(NewMBB));
1393  IP = std::find(WaterList.begin(), WaterList.end(), WaterBB);
1394  if (IP != WaterList.end())
1395  NewWaterList.erase(WaterBB);
1396 
1397  // We are adding new water. Update NewWaterList.
1398  NewWaterList.insert(NewIsland);
1399  }
1400 
1401  // Remove the original WaterList entry; we want subsequent insertions in
1402  // this vicinity to go after the one we're about to insert. This
1403  // considerably reduces the number of times we have to move the same CPE
1404  // more than once and is also important to ensure the algorithm terminates.
1405  if (IP != WaterList.end())
1406  WaterList.erase(IP);
1407 
1408  // Okay, we know we can put an island before NewMBB now, do it!
1409  MF->insert(NewMBB, NewIsland);
1410 
1411  // Update internal data structures to account for the newly inserted MBB.
1412  updateForInsertedWaterBlock(NewIsland);
1413 
1414  // Decrement the old entry, and remove it if refcount becomes 0.
1415  decrementCPEReferenceCount(CPI, CPEMI);
1416 
1417  // No existing clone of this CPE is within range.
1418  // We will be generating a new clone. Get a UID for it.
1419  unsigned ID = createPICLabelUId();
1420 
1421  // Now that we have an island to add the CPE to, clone the original CPE and
1422  // add it to the island.
1423  U.HighWaterMark = NewIsland;
1424  U.CPEMI = BuildMI(NewIsland, DebugLoc(), TII->get(Mips::CONSTPOOL_ENTRY))
1425  .addImm(ID).addConstantPoolIndex(CPI).addImm(Size);
1426  CPEntries[CPI].push_back(CPEntry(U.CPEMI, ID, 1));
1427  ++NumCPEs;
1428 
1429  // Mark the basic block as aligned as required by the const-pool entry.
1430  NewIsland->setAlignment(getCPELogAlign(U.CPEMI));
1431 
1432  // Increase the size of the island block to account for the new entry.
1433  BBInfo[NewIsland->getNumber()].Size += Size;
1434  adjustBBOffsetsAfter(std::prev(MachineFunction::iterator(NewIsland)));
1435 
1436 
1437 
1438  // Finally, change the CPI in the instruction operand to be ID.
1439  for (unsigned i = 0, e = UserMI->getNumOperands(); i != e; ++i)
1440  if (UserMI->getOperand(i).isCPI()) {
1441  UserMI->getOperand(i).setIndex(ID);
1442  break;
1443  }
1444 
1445  DEBUG(dbgs() << " Moved CPE to #" << ID << " CPI=" << CPI
1446  << format(" offset=%#x\n", BBInfo[NewIsland->getNumber()].Offset));
1447 
1448  return true;
1449 }
1450 
1451 /// removeDeadCPEMI - Remove a dead constant pool entry instruction. Update
1452 /// sizes and offsets of impacted basic blocks.
1453 void MipsConstantIslands::removeDeadCPEMI(MachineInstr *CPEMI) {
1454  MachineBasicBlock *CPEBB = CPEMI->getParent();
1455  unsigned Size = CPEMI->getOperand(2).getImm();
1456  CPEMI->eraseFromParent();
1457  BBInfo[CPEBB->getNumber()].Size -= Size;
1458  // All succeeding offsets have the current size value added in, fix this.
1459  if (CPEBB->empty()) {
1460  BBInfo[CPEBB->getNumber()].Size = 0;
1461 
1462  // This block no longer needs to be aligned.
1463  CPEBB->setAlignment(0);
1464  } else
1465  // Entries are sorted by descending alignment, so realign from the front.
1466  CPEBB->setAlignment(getCPELogAlign(CPEBB->begin()));
1467 
1468  adjustBBOffsetsAfter(CPEBB);
1469  // An island has only one predecessor BB and one successor BB. Check if
1470  // this BB's predecessor jumps directly to this BB's successor. This
1471  // shouldn't happen currently.
1472  assert(!BBIsJumpedOver(CPEBB) && "How did this happen?");
1473  // FIXME: remove the empty blocks after all the work is done?
1474 }
1475 
1476 /// removeUnusedCPEntries - Remove constant pool entries whose refcounts
1477 /// are zero.
1478 bool MipsConstantIslands::removeUnusedCPEntries() {
1479  unsigned MadeChange = false;
1480  for (unsigned i = 0, e = CPEntries.size(); i != e; ++i) {
1481  std::vector<CPEntry> &CPEs = CPEntries[i];
1482  for (unsigned j = 0, ee = CPEs.size(); j != ee; ++j) {
1483  if (CPEs[j].RefCount == 0 && CPEs[j].CPEMI) {
1484  removeDeadCPEMI(CPEs[j].CPEMI);
1485  CPEs[j].CPEMI = nullptr;
1486  MadeChange = true;
1487  }
1488  }
1489  }
1490  return MadeChange;
1491 }
1492 
1493 /// isBBInRange - Returns true if the distance between specific MI and
1494 /// specific BB can fit in MI's displacement field.
1495 bool MipsConstantIslands::isBBInRange
1496  (MachineInstr *MI,MachineBasicBlock *DestBB, unsigned MaxDisp) {
1497 
1498 unsigned PCAdj = 4;
1499 
1500  unsigned BrOffset = getOffsetOf(MI) + PCAdj;
1501  unsigned DestOffset = BBInfo[DestBB->getNumber()].Offset;
1502 
1503  DEBUG(dbgs() << "Branch of destination BB#" << DestBB->getNumber()
1504  << " from BB#" << MI->getParent()->getNumber()
1505  << " max delta=" << MaxDisp
1506  << " from " << getOffsetOf(MI) << " to " << DestOffset
1507  << " offset " << int(DestOffset-BrOffset) << "\t" << *MI);
1508 
1509  if (BrOffset <= DestOffset) {
1510  // Branch before the Dest.
1511  if (DestOffset-BrOffset <= MaxDisp)
1512  return true;
1513  } else {
1514  if (BrOffset-DestOffset <= MaxDisp)
1515  return true;
1516  }
1517  return false;
1518 }
1519 
1520 /// fixupImmediateBr - Fix up an immediate branch whose destination is too far
1521 /// away to fit in its displacement field.
1522 bool MipsConstantIslands::fixupImmediateBr(ImmBranch &Br) {
1523  MachineInstr *MI = Br.MI;
1524  unsigned TargetOperand = branchTargetOperand(MI);
1525  MachineBasicBlock *DestBB = MI->getOperand(TargetOperand).getMBB();
1526 
1527  // Check to see if the DestBB is already in-range.
1528  if (isBBInRange(MI, DestBB, Br.MaxDisp))
1529  return false;
1530 
1531  if (!Br.isCond)
1532  return fixupUnconditionalBr(Br);
1533  return fixupConditionalBr(Br);
1534 }
1535 
1536 /// fixupUnconditionalBr - Fix up an unconditional branch whose destination is
1537 /// too far away to fit in its displacement field. If the LR register has been
1538 /// spilled in the epilogue, then we can use BL to implement a far jump.
1539 /// Otherwise, add an intermediate branch instruction to a branch.
1540 bool
1541 MipsConstantIslands::fixupUnconditionalBr(ImmBranch &Br) {
1542  MachineInstr *MI = Br.MI;
1543  MachineBasicBlock *MBB = MI->getParent();
1544  MachineBasicBlock *DestBB = MI->getOperand(0).getMBB();
1545  // Use BL to implement far jump.
1546  unsigned BimmX16MaxDisp = ((1 << 16)-1) * 2;
1547  if (isBBInRange(MI, DestBB, BimmX16MaxDisp)) {
1548  Br.MaxDisp = BimmX16MaxDisp;
1549  MI->setDesc(TII->get(Mips::BimmX16));
1550  }
1551  else {
1552  // need to give the math a more careful look here
1553  // this is really a segment address and not
1554  // a PC relative address. FIXME. But I think that
1555  // just reducing the bits by 1 as I've done is correct.
1556  // The basic block we are branching too much be longword aligned.
1557  // we know that RA is saved because we always save it right now.
1558  // this requirement will be relaxed later but we also have an alternate
1559  // way to implement this that I will implement that does not need jal.
1560  // We should have a way to back out this alignment restriction if we "can" later.
1561  // but it is not harmful.
1562  //
1563  DestBB->setAlignment(2);
1564  Br.MaxDisp = ((1<<24)-1) * 2;
1565  MI->setDesc(TII->get(Mips::JalB16));
1566  }
1567  BBInfo[MBB->getNumber()].Size += 2;
1568  adjustBBOffsetsAfter(MBB);
1569  HasFarJump = true;
1570  ++NumUBrFixed;
1571 
1572  DEBUG(dbgs() << " Changed B to long jump " << *MI);
1573 
1574  return true;
1575 }
1576 
1577 
1578 /// fixupConditionalBr - Fix up a conditional branch whose destination is too
1579 /// far away to fit in its displacement field. It is converted to an inverse
1580 /// conditional branch + an unconditional branch to the destination.
1581 bool
1582 MipsConstantIslands::fixupConditionalBr(ImmBranch &Br) {
1583  MachineInstr *MI = Br.MI;
1584  unsigned TargetOperand = branchTargetOperand(MI);
1585  MachineBasicBlock *DestBB = MI->getOperand(TargetOperand).getMBB();
1586  unsigned Opcode = MI->getOpcode();
1587  unsigned LongFormOpcode = longformBranchOpcode(Opcode);
1588  unsigned LongFormMaxOff = branchMaxOffsets(LongFormOpcode);
1589 
1590  // Check to see if the DestBB is already in-range.
1591  if (isBBInRange(MI, DestBB, LongFormMaxOff)) {
1592  Br.MaxDisp = LongFormMaxOff;
1593  MI->setDesc(TII->get(LongFormOpcode));
1594  return true;
1595  }
1596 
1597  // Add an unconditional branch to the destination and invert the branch
1598  // condition to jump over it:
1599  // bteqz L1
1600  // =>
1601  // bnez L2
1602  // b L1
1603  // L2:
1604 
1605  // If the branch is at the end of its MBB and that has a fall-through block,
1606  // direct the updated conditional branch to the fall-through block. Otherwise,
1607  // split the MBB before the next instruction.
1608  MachineBasicBlock *MBB = MI->getParent();
1609  MachineInstr *BMI = &MBB->back();
1610  bool NeedSplit = (BMI != MI) || !BBHasFallthrough(MBB);
1611  unsigned OppositeBranchOpcode = TII->getOppositeBranchOpc(Opcode);
1612 
1613  ++NumCBrFixed;
1614  if (BMI != MI) {
1615  if (std::next(MachineBasicBlock::iterator(MI)) == std::prev(MBB->end()) &&
1616  isUnconditionalBranch(BMI->getOpcode())) {
1617  // Last MI in the BB is an unconditional branch. Can we simply invert the
1618  // condition and swap destinations:
1619  // beqz L1
1620  // b L2
1621  // =>
1622  // bnez L2
1623  // b L1
1624  unsigned BMITargetOperand = branchTargetOperand(BMI);
1625  MachineBasicBlock *NewDest =
1626  BMI->getOperand(BMITargetOperand).getMBB();
1627  if (isBBInRange(MI, NewDest, Br.MaxDisp)) {
1628  DEBUG(dbgs() << " Invert Bcc condition and swap its destination with "
1629  << *BMI);
1630  MI->setDesc(TII->get(OppositeBranchOpcode));
1631  BMI->getOperand(BMITargetOperand).setMBB(DestBB);
1632  MI->getOperand(TargetOperand).setMBB(NewDest);
1633  return true;
1634  }
1635  }
1636  }
1637 
1638 
1639  if (NeedSplit) {
1640  splitBlockBeforeInstr(MI);
1641  // No need for the branch to the next block. We're adding an unconditional
1642  // branch to the destination.
1643  int delta = TII->GetInstSizeInBytes(&MBB->back());
1644  BBInfo[MBB->getNumber()].Size -= delta;
1645  MBB->back().eraseFromParent();
1646  // BBInfo[SplitBB].Offset is wrong temporarily, fixed below
1647  }
1648  MachineBasicBlock *NextBB = std::next(MachineFunction::iterator(MBB));
1649 
1650  DEBUG(dbgs() << " Insert B to BB#" << DestBB->getNumber()
1651  << " also invert condition and change dest. to BB#"
1652  << NextBB->getNumber() << "\n");
1653 
1654  // Insert a new conditional branch and a new unconditional branch.
1655  // Also update the ImmBranch as well as adding a new entry for the new branch.
1656  if (MI->getNumExplicitOperands() == 2) {
1657  BuildMI(MBB, DebugLoc(), TII->get(OppositeBranchOpcode))
1658  .addReg(MI->getOperand(0).getReg())
1659  .addMBB(NextBB);
1660  } else {
1661  BuildMI(MBB, DebugLoc(), TII->get(OppositeBranchOpcode))
1662  .addMBB(NextBB);
1663  }
1664  Br.MI = &MBB->back();
1665  BBInfo[MBB->getNumber()].Size += TII->GetInstSizeInBytes(&MBB->back());
1666  BuildMI(MBB, DebugLoc(), TII->get(Br.UncondBr)).addMBB(DestBB);
1667  BBInfo[MBB->getNumber()].Size += TII->GetInstSizeInBytes(&MBB->back());
1668  unsigned MaxDisp = getUnconditionalBrDisp(Br.UncondBr);
1669  ImmBranches.push_back(ImmBranch(&MBB->back(), MaxDisp, false, Br.UncondBr));
1670 
1671  // Remove the old conditional branch. It may or may not still be in MBB.
1672  BBInfo[MI->getParent()->getNumber()].Size -= TII->GetInstSizeInBytes(MI);
1673  MI->eraseFromParent();
1674  adjustBBOffsetsAfter(MBB);
1675  return true;
1676 }
1677 
1678 
1679 void MipsConstantIslands::prescanForConstants() {
1680  unsigned J = 0;
1681  (void)J;
1682  for (MachineFunction::iterator B =
1683  MF->begin(), E = MF->end(); B != E; ++B) {
1685  B->instr_begin(), EB = B->instr_end(); I != EB; ++I) {
1686  switch(I->getDesc().getOpcode()) {
1687  case Mips::LwConstant32: {
1688  PrescannedForConstants = true;
1689  DEBUG(dbgs() << "constant island constant " << *I << "\n");
1690  J = I->getNumOperands();
1691  DEBUG(dbgs() << "num operands " << J << "\n");
1692  MachineOperand& Literal = I->getOperand(1);
1693  if (Literal.isImm()) {
1694  int64_t V = Literal.getImm();
1695  DEBUG(dbgs() << "literal " << V << "\n");
1696  Type *Int32Ty =
1697  Type::getInt32Ty(MF->getFunction()->getContext());
1698  const Constant *C = ConstantInt::get(Int32Ty, V);
1699  unsigned index = MCP->getConstantPoolIndex(C, 4);
1700  I->getOperand(2).ChangeToImmediate(index);
1701  DEBUG(dbgs() << "constant island constant " << *I << "\n");
1702  I->setDesc(TII->get(Mips::LwRxPcTcp16));
1703  I->RemoveOperand(1);
1704  I->RemoveOperand(1);
1705  I->addOperand(MachineOperand::CreateCPI(index, 0));
1706  I->addOperand(MachineOperand::CreateImm(4));
1707  }
1708  break;
1709  }
1710  default:
1711  break;
1712  }
1713  }
1714  }
1715 }
1716 
unsigned succ_size() const
const MachineFunction * getParent() const
getParent - Return the MachineFunction containing this basic block.
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:104
The MachineConstantPool class keeps track of constants referenced by a function which must be spilled...
static unsigned int branchTargetOperand(MachineInstr *MI)
static bool isUnconditionalBranch(unsigned int Opcode)
static bool CompareMBBNumbers(const MachineBasicBlock *LHS, const MachineBasicBlock *RHS)
CompareMBBNumbers - Little predicate function to sort the WaterList by MBB ID.
STATISTIC(NumFunctions,"Total number of functions")
void RenumberBlocks(MachineBasicBlock *MBBFrom=nullptr)
RenumberBlocks - This discards all of the MachineBasicBlock numbers and recomputes them...
MachineBasicBlock * getMBB() const
int getNumber() const
getNumber - MachineBasicBlocks are uniquely numbered at the function level, unless they're not in a M...
static unsigned int branchMaxOffsets(unsigned int Opcode)
A debug info location.
Definition: DebugLoc.h:34
F(f)
FunctionType * getType(LLVMContext &Context, ID id, ArrayRef< Type * > Tys=None)
Return the function type for an intrinsic.
Definition: Function.cpp:822
#define op(i)
Instructions::iterator instr_iterator
void setAlignment(unsigned Align)
setAlignment - Set alignment of the basic block.
LLVM_ATTRIBUTE_NORETURN void report_fatal_error(const char *reason, bool gen_crash_diag=true)
Reports a serious error, calling any installed error handler.
const TargetSubtargetInfo & getSubtarget() const
getSubtarget - Return the subtarget for which this machine code is being compiled.
This file declares the MachineConstantPool class which is an abstract constant pool to keep track of ...
MachineFunctionPass - This class adapts the FunctionPass interface to allow convenient creation of pa...
const HexagonInstrInfo * TII
bool isImm() const
isImm - Tests if this is a MO_Immediate operand.
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Definition: ErrorHandling.h:98
void eraseFromParent()
Unlink 'this' from the containing basic block and delete it.
static bool BBHasFallthrough(MachineBasicBlock *MBB)
BBHasFallthrough - Return true if the specified basic block can fallthrough into the block immediatel...
std::vector< MachineBasicBlock * >::iterator succ_iterator
void setIndex(int Idx)
static cl::opt< bool > AlignConstantIslands("mips-align-constant-islands", cl::Hidden, cl::init(true), cl::desc("Align constant islands in code"))
#define false
Definition: ConvertUTF.c:65
const MachineInstrBuilder & addImm(int64_t Val) const
addImm - Add a new immediate operand.
unsigned getNumOperands() const
Access to explicit operands of the instruction.
Definition: MachineInstr.h:271
bool isCPI() const
isCPI - Tests if this is a MO_ConstantPoolIndex operand.
void transferSuccessors(MachineBasicBlock *fromMBB)
transferSuccessors - Transfers all the successors from MBB to this machine basic block (i...
int64_t getImm() const
instr_iterator insert(instr_iterator I, MachineInstr *M)
Insert MI into the instruction list before I, possibly inside a bundle.
const BasicBlock * getBasicBlock() const
getBasicBlock - Return the LLVM basic block that this instance corresponded to originally.
unsigned getOpcode() const
Returns the opcode of this MachineInstr.
Definition: MachineInstr.h:267
const MachineBasicBlock * getParent() const
Definition: MachineInstr.h:120
format_object< Ts...> format(const char *Fmt, const Ts &...Vals)
These are helper functions used to produce formatted output.
Definition: Format.h:111
static cl::opt< int > ConstantIslandsSmallOffset("mips-constant-islands-small-offset", cl::init(0), cl::desc("Make small offsets be this amount for testing purposes"), cl::Hidden)
bundle_iterator< MachineInstr, instr_iterator > iterator
static cl::opt< bool > NoLoadRelaxation("mips-constant-islands-no-load-relaxation", cl::init(false), cl::desc("Don't relax loads to long loads - for testing purposes"), cl::Hidden)
#define rc(i)
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:325
static unsigned int longformBranchOpcode(unsigned int Opcode)
static MachineOperand CreateCPI(unsigned Idx, int Offset, unsigned char TargetFlags=0)
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:45
static bool BBIsJumpedOver(MachineBasicBlock *MBB)
BBIsJumpedOver - Return true of the specified basic block's only predecessor unconditionally branches...
This is an important base class in LLVM.
Definition: Constant.h:41
SmallSet - This maintains a set of unique values, optimizing for the case when the set is small (less...
Definition: SmallSet.h:32
const MachineOperand & getOperand(unsigned i) const
Definition: MachineInstr.h:273
void setMBB(MachineBasicBlock *MBB)
unsigned getNumExplicitOperands() const
Returns the number of non-implicit operands.
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:294
MachineConstantPool * getConstantPool()
getConstantPool - Return the constant pool object for the current function.
MachineInstrBuilder BuildMI(MachineFunction &MF, DebugLoc DL, const MCInstrDesc &MCID)
BuildMI - Builder interface.
static unsigned getUnconditionalBrDisp(int Opc)
getUnconditionalBrDisp - Returns the maximum displacement that can fit in the specific unconditional ...
static bool useConstantIslands()
void setDesc(const MCInstrDesc &tid)
Replace the instruction descriptor (thus opcode) of the current instruction with a new one...
uint64_t getTypeAllocSize(Type *Ty) const
Returns the offset in bytes between successive objects of the specified type, including alignment pad...
Definition: DataLayout.h:388
MachineOperand class - Representation of each machine instruction operand.
This is a 'vector' (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:861
static Constant * get(Type *Ty, uint64_t V, bool isSigned=false)
If Ty is a vector type, return a Constant with a splat of the given value.
Definition: Constants.cpp:582
static cl::opt< AlignMode > Align(cl::desc("Load/store alignment support"), cl::Hidden, cl::init(NoStrictAlign), cl::values(clEnumValN(StrictAlign,"aarch64-strict-align","Disallow all unaligned memory accesses"), clEnumValN(NoStrictAlign,"aarch64-no-strict-align","Allow unaligned memory accesses"), clEnumValEnd))
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:123
unsigned Log2_32(uint32_t Value)
Log2_32 - This function returns the floor log base 2 of the specified value, -1 if the value is zero...
Definition: MathExtras.h:468
Representation of each machine instruction.
Definition: MachineInstr.h:51
FunctionPass * createMipsConstantIslandPass(MipsTargetMachine &tm)
createMipsLongBranchPass - Returns a pass that converts branches to long branches.
void splice(iterator Where, MachineBasicBlock *Other, iterator From)
Take an instruction from MBB 'Other' at the position From, and insert it into this MBB right before '...
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:239
const MachineInstrBuilder & addConstantPoolIndex(unsigned Idx, int Offset=0, unsigned char TargetFlags=0) const
static MachineOperand CreateImm(int64_t Val)
void push_back(MachineInstr *MI)
#define I(x, y, z)
Definition: MD5.cpp:54
MipsFunctionInfo - This class is derived from MachineFunction private Mips target-specific informatio...
void size_t size
unsigned getReg() const
getReg - Returns the register number.
std::reverse_iterator< iterator > reverse_iterator
uint64_t OffsetToAlignment(uint64_t Value, uint64_t Align)
Returns the offset to the next integer (mod 2**64) that is greater than or equal to Value and is a mu...
Definition: MathExtras.h:616
BasicBlockListType::iterator iterator
#define DEBUG(X)
Definition: Debug.h:92
Primary interface to the complete machine description for the target machine.
C - The default llvm calling convention, compatible with C.
Definition: CallingConv.h:34
bool isPowerOf2_32(uint32_t Value)
isPowerOf2_32 - This function returns true if the argument is a power of two > 0. ...
Definition: MathExtras.h:354
void addSuccessor(MachineBasicBlock *succ, uint32_t weight=0)
addSuccessor - Add succ as a successor of this MachineBasicBlock.
unsigned pred_size() const
unsigned getAlignment() const
getAlignment - Return alignment of the basic block.