LLVM  6.0.0svn
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 // This pass is used to make Pc relative loads of constants.
11 // For now, only Mips16 will use this.
12 //
13 // Loading constants inline is expensive on Mips16 and it's in general better
14 // to place the constant nearby in code space and then it can be loaded with a
15 // simple 16 bit load instruction.
16 //
17 // The constants can be not just numbers but addresses of functions and labels.
18 // This can be particularly helpful in static relocation mode for embedded
19 // non-linux targets.
20 //
21 //===----------------------------------------------------------------------===//
22 
23 #include "Mips.h"
24 #include "Mips16InstrInfo.h"
25 #include "MipsMachineFunction.h"
26 #include "MipsSubtarget.h"
27 #include "llvm/ADT/STLExtras.h"
28 #include "llvm/ADT/SmallSet.h"
29 #include "llvm/ADT/SmallVector.h"
30 #include "llvm/ADT/Statistic.h"
31 #include "llvm/ADT/StringRef.h"
40 #include "llvm/IR/Constants.h"
41 #include "llvm/IR/DataLayout.h"
42 #include "llvm/IR/DebugLoc.h"
43 #include "llvm/IR/Function.h"
44 #include "llvm/IR/Type.h"
46 #include "llvm/Support/Compiler.h"
47 #include "llvm/Support/Debug.h"
49 #include "llvm/Support/Format.h"
52 #include <algorithm>
53 #include <cassert>
54 #include <cstdint>
55 #include <iterator>
56 #include <vector>
57 
58 using namespace llvm;
59 
60 #define DEBUG_TYPE "mips-constant-islands"
61 
62 STATISTIC(NumCPEs, "Number of constpool entries");
63 STATISTIC(NumSplit, "Number of uncond branches inserted");
64 STATISTIC(NumCBrFixed, "Number of cond branches fixed");
65 STATISTIC(NumUBrFixed, "Number of uncond branches fixed");
66 
67 // FIXME: This option should be removed once it has received sufficient testing.
68 static cl::opt<bool>
69 AlignConstantIslands("mips-align-constant-islands", cl::Hidden, cl::init(true),
70  cl::desc("Align constant islands in code"));
71 
72 // Rather than do make check tests with huge amounts of code, we force
73 // the test to use this amount.
75  "mips-constant-islands-small-offset",
76  cl::init(0),
77  cl::desc("Make small offsets be this amount for testing purposes"),
78  cl::Hidden);
79 
80 // For testing purposes we tell it to not use relaxed load forms so that it
81 // will split blocks.
83  "mips-constant-islands-no-load-relaxation",
84  cl::init(false),
85  cl::desc("Don't relax loads to long loads - for testing purposes"),
86  cl::Hidden);
87 
88 static unsigned int branchTargetOperand(MachineInstr *MI) {
89  switch (MI->getOpcode()) {
90  case Mips::Bimm16:
91  case Mips::BimmX16:
92  case Mips::Bteqz16:
93  case Mips::BteqzX16:
94  case Mips::Btnez16:
95  case Mips::BtnezX16:
96  case Mips::JalB16:
97  return 0;
98  case Mips::BeqzRxImm16:
99  case Mips::BeqzRxImmX16:
100  case Mips::BnezRxImm16:
101  case Mips::BnezRxImmX16:
102  return 1;
103  }
104  llvm_unreachable("Unknown branch type");
105 }
106 
107 static unsigned int longformBranchOpcode(unsigned int Opcode) {
108  switch (Opcode) {
109  case Mips::Bimm16:
110  case Mips::BimmX16:
111  return Mips::BimmX16;
112  case Mips::Bteqz16:
113  case Mips::BteqzX16:
114  return Mips::BteqzX16;
115  case Mips::Btnez16:
116  case Mips::BtnezX16:
117  return Mips::BtnezX16;
118  case Mips::JalB16:
119  return Mips::JalB16;
120  case Mips::BeqzRxImm16:
121  case Mips::BeqzRxImmX16:
122  return Mips::BeqzRxImmX16;
123  case Mips::BnezRxImm16:
124  case Mips::BnezRxImmX16:
125  return Mips::BnezRxImmX16;
126  }
127  llvm_unreachable("Unknown branch type");
128 }
129 
130 // FIXME: need to go through this whole constant islands port and check the math
131 // for branch ranges and clean this up and make some functions to calculate things
132 // that are done many times identically.
133 // Need to refactor some of the code to call this routine.
134 static unsigned int branchMaxOffsets(unsigned int Opcode) {
135  unsigned Bits, Scale;
136  switch (Opcode) {
137  case Mips::Bimm16:
138  Bits = 11;
139  Scale = 2;
140  break;
141  case Mips::BimmX16:
142  Bits = 16;
143  Scale = 2;
144  break;
145  case Mips::BeqzRxImm16:
146  Bits = 8;
147  Scale = 2;
148  break;
149  case Mips::BeqzRxImmX16:
150  Bits = 16;
151  Scale = 2;
152  break;
153  case Mips::BnezRxImm16:
154  Bits = 8;
155  Scale = 2;
156  break;
157  case Mips::BnezRxImmX16:
158  Bits = 16;
159  Scale = 2;
160  break;
161  case Mips::Bteqz16:
162  Bits = 8;
163  Scale = 2;
164  break;
165  case Mips::BteqzX16:
166  Bits = 16;
167  Scale = 2;
168  break;
169  case Mips::Btnez16:
170  Bits = 8;
171  Scale = 2;
172  break;
173  case Mips::BtnezX16:
174  Bits = 16;
175  Scale = 2;
176  break;
177  default:
178  llvm_unreachable("Unknown branch type");
179  }
180  unsigned MaxOffs = ((1 << (Bits-1))-1) * Scale;
181  return MaxOffs;
182 }
183 
184 namespace {
185 
186  using Iter = MachineBasicBlock::iterator;
187  using ReverseIter = MachineBasicBlock::reverse_iterator;
188 
189  /// MipsConstantIslands - Due to limited PC-relative displacements, Mips
190  /// requires constant pool entries to be scattered among the instructions
191  /// inside a function. To do this, it completely ignores the normal LLVM
192  /// constant pool; instead, it places constants wherever it feels like with
193  /// special instructions.
194  ///
195  /// The terminology used in this pass includes:
196  /// Islands - Clumps of constants placed in the function.
197  /// Water - Potential places where an island could be formed.
198  /// CPE - A constant pool entry that has been placed somewhere, which
199  /// tracks a list of users.
200 
201  class MipsConstantIslands : public MachineFunctionPass {
202  /// BasicBlockInfo - Information about the offset and size of a single
203  /// basic block.
204  struct BasicBlockInfo {
205  /// Offset - Distance from the beginning of the function to the beginning
206  /// of this basic block.
207  ///
208  /// Offsets are computed assuming worst case padding before an aligned
209  /// block. This means that subtracting basic block offsets always gives a
210  /// conservative estimate of the real distance which may be smaller.
211  ///
212  /// Because worst case padding is used, the computed offset of an aligned
213  /// block may not actually be aligned.
214  unsigned Offset = 0;
215 
216  /// Size - Size of the basic block in bytes. If the block contains
217  /// inline assembly, this is a worst case estimate.
218  ///
219  /// The size does not include any alignment padding whether from the
220  /// beginning of the block, or from an aligned jump table at the end.
221  unsigned Size = 0;
222 
223  BasicBlockInfo() = default;
224 
225  // FIXME: ignore LogAlign for this patch
226  //
227  unsigned postOffset(unsigned LogAlign = 0) const {
228  unsigned PO = Offset + Size;
229  return PO;
230  }
231  };
232 
233  std::vector<BasicBlockInfo> BBInfo;
234 
235  /// WaterList - A sorted list of basic blocks where islands could be placed
236  /// (i.e. blocks that don't fall through to the following block, due
237  /// to a return, unreachable, or unconditional branch).
238  std::vector<MachineBasicBlock*> WaterList;
239 
240  /// NewWaterList - The subset of WaterList that was created since the
241  /// previous iteration by inserting unconditional branches.
242  SmallSet<MachineBasicBlock*, 4> NewWaterList;
243 
244  using water_iterator = std::vector<MachineBasicBlock *>::iterator;
245 
246  /// CPUser - One user of a constant pool, keeping the machine instruction
247  /// pointer, the constant pool being referenced, and the max displacement
248  /// allowed from the instruction to the CP. The HighWaterMark records the
249  /// highest basic block where a new CPEntry can be placed. To ensure this
250  /// pass terminates, the CP entries are initially placed at the end of the
251  /// function and then move monotonically to lower addresses. The
252  /// exception to this rule is when the current CP entry for a particular
253  /// CPUser is out of range, but there is another CP entry for the same
254  /// constant value in range. We want to use the existing in-range CP
255  /// entry, but if it later moves out of range, the search for new water
256  /// should resume where it left off. The HighWaterMark is used to record
257  /// that point.
258  struct CPUser {
259  MachineInstr *MI;
260  MachineInstr *CPEMI;
261  MachineBasicBlock *HighWaterMark;
262 
263  private:
264  unsigned MaxDisp;
265  unsigned LongFormMaxDisp; // mips16 has 16/32 bit instructions
266  // with different displacements
267  unsigned LongFormOpcode;
268 
269  public:
270  bool NegOk;
271 
272  CPUser(MachineInstr *mi, MachineInstr *cpemi, unsigned maxdisp,
273  bool neg,
274  unsigned longformmaxdisp, unsigned longformopcode)
275  : MI(mi), CPEMI(cpemi), MaxDisp(maxdisp),
276  LongFormMaxDisp(longformmaxdisp), LongFormOpcode(longformopcode),
277  NegOk(neg){
278  HighWaterMark = CPEMI->getParent();
279  }
280 
281  /// getMaxDisp - Returns the maximum displacement supported by MI.
282  unsigned getMaxDisp() const {
283  unsigned xMaxDisp = ConstantIslandsSmallOffset?
285  return xMaxDisp;
286  }
287 
288  void setMaxDisp(unsigned val) {
289  MaxDisp = val;
290  }
291 
292  unsigned getLongFormMaxDisp() const {
293  return LongFormMaxDisp;
294  }
295 
296  unsigned getLongFormOpcode() const {
297  return LongFormOpcode;
298  }
299  };
300 
301  /// CPUsers - Keep track of all of the machine instructions that use various
302  /// constant pools and their max displacement.
303  std::vector<CPUser> CPUsers;
304 
305  /// CPEntry - One per constant pool entry, keeping the machine instruction
306  /// pointer, the constpool index, and the number of CPUser's which
307  /// reference this entry.
308  struct CPEntry {
309  MachineInstr *CPEMI;
310  unsigned CPI;
311  unsigned RefCount;
312 
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 
334  ImmBranch(MachineInstr *mi, unsigned maxdisp, bool cond, int ubr)
335  : MI(mi), MaxDisp(maxdisp), isCond(cond), UncondBr(ubr) {}
336  };
337 
338  /// ImmBranches - Keep track of all the immediate branch instructions.
339  ///
340  std::vector<ImmBranch> ImmBranches;
341 
342  /// HasFarJump - True if any far jump instruction has been emitted during
343  /// the branch fix up pass.
344  bool HasFarJump;
345 
346  const MipsSubtarget *STI = nullptr;
347  const Mips16InstrInfo *TII;
348  MipsFunctionInfo *MFI;
349  MachineFunction *MF = nullptr;
350  MachineConstantPool *MCP = nullptr;
351 
352  unsigned PICLabelUId;
353  bool PrescannedForConstants = false;
354 
355  void initPICLabelUId(unsigned UId) {
356  PICLabelUId = UId;
357  }
358 
359  unsigned createPICLabelUId() {
360  return PICLabelUId++;
361  }
362 
363  public:
364  static char ID;
365 
366  MipsConstantIslands() : MachineFunctionPass(ID) {}
367 
368  StringRef getPassName() const override { return "Mips Constant Islands"; }
369 
370  bool runOnMachineFunction(MachineFunction &F) override;
371 
372  MachineFunctionProperties getRequiredProperties() const override {
375  }
376 
377  void doInitialPlacement(std::vector<MachineInstr*> &CPEMIs);
378  CPEntry *findConstPoolEntry(unsigned CPI, const MachineInstr *CPEMI);
379  unsigned getCPELogAlign(const MachineInstr &CPEMI);
380  void initializeFunctionInfo(const std::vector<MachineInstr*> &CPEMIs);
381  unsigned getOffsetOf(MachineInstr *MI) const;
382  unsigned getUserOffset(CPUser&) const;
383  void dumpBBs();
384 
385  bool isOffsetInRange(unsigned UserOffset, unsigned TrialOffset,
386  unsigned Disp, bool NegativeOK);
387  bool isOffsetInRange(unsigned UserOffset, unsigned TrialOffset,
388  const CPUser &U);
389 
391  MachineBasicBlock *splitBlockBeforeInstr(MachineInstr &MI);
392  void updateForInsertedWaterBlock(MachineBasicBlock *NewBB);
393  void adjustBBOffsetsAfter(MachineBasicBlock *BB);
394  bool decrementCPEReferenceCount(unsigned CPI, MachineInstr* CPEMI);
395  int findInRangeCPEntry(CPUser& U, unsigned UserOffset);
396  int findLongFormInRangeCPEntry(CPUser& U, unsigned UserOffset);
397  bool findAvailableWater(CPUser&U, unsigned UserOffset,
398  water_iterator &WaterIter);
399  void createNewWater(unsigned CPUserIndex, unsigned UserOffset,
400  MachineBasicBlock *&NewMBB);
401  bool handleConstantPoolUser(unsigned CPUserIndex);
402  void removeDeadCPEMI(MachineInstr *CPEMI);
403  bool removeUnusedCPEntries();
404  bool isCPEntryInRange(MachineInstr *MI, unsigned UserOffset,
405  MachineInstr *CPEMI, unsigned Disp, bool NegOk,
406  bool DoDump = false);
407  bool isWaterInRange(unsigned UserOffset, MachineBasicBlock *Water,
408  CPUser &U, unsigned &Growth);
409  bool isBBInRange(MachineInstr *MI, MachineBasicBlock *BB, unsigned Disp);
410  bool fixupImmediateBr(ImmBranch &Br);
411  bool fixupConditionalBr(ImmBranch &Br);
412  bool fixupUnconditionalBr(ImmBranch &Br);
413 
414  void prescanForConstants();
415  };
416 
417 } // end anonymous namespace
418 
419 char MipsConstantIslands::ID = 0;
420 
421 bool MipsConstantIslands::isOffsetInRange
422  (unsigned UserOffset, unsigned TrialOffset,
423  const CPUser &U) {
424  return isOffsetInRange(UserOffset, TrialOffset,
425  U.getMaxDisp(), U.NegOk);
426 }
427 
428 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
429 /// print block size and offset information - debugging
430 LLVM_DUMP_METHOD void MipsConstantIslands::dumpBBs() {
431  for (unsigned J = 0, E = BBInfo.size(); J !=E; ++J) {
432  const BasicBlockInfo &BBI = BBInfo[J];
433  dbgs() << format("%08x BB#%u\t", BBI.Offset, J)
434  << format(" size=%#x\n", BBInfo[J].Size);
435  }
436 }
437 #endif
438 
439 bool MipsConstantIslands::runOnMachineFunction(MachineFunction &mf) {
440  // The intention is for this to be a mips16 only pass for now
441  // FIXME:
442  MF = &mf;
443  MCP = mf.getConstantPool();
444  STI = &static_cast<const MipsSubtarget &>(mf.getSubtarget());
445  DEBUG(dbgs() << "constant island machine function " << "\n");
446  if (!STI->inMips16Mode() || !MipsSubtarget::useConstantIslands()) {
447  return false;
448  }
449  TII = (const Mips16InstrInfo *)STI->getInstrInfo();
450  MFI = MF->getInfo<MipsFunctionInfo>();
451  DEBUG(dbgs() << "constant island processing " << "\n");
452  //
453  // will need to make predermination if there is any constants we need to
454  // put in constant islands. TBD.
455  //
456  if (!PrescannedForConstants) prescanForConstants();
457 
458  HasFarJump = false;
459  // This pass invalidates liveness information when it splits basic blocks.
460  MF->getRegInfo().invalidateLiveness();
461 
462  // Renumber all of the machine basic blocks in the function, guaranteeing that
463  // the numbers agree with the position of the block in the function.
464  MF->RenumberBlocks();
465 
466  bool MadeChange = false;
467 
468  // Perform the initial placement of the constant pool entries. To start with,
469  // we put them all at the end of the function.
470  std::vector<MachineInstr*> CPEMIs;
471  if (!MCP->isEmpty())
472  doInitialPlacement(CPEMIs);
473 
474  /// The next UID to take is the first unused one.
475  initPICLabelUId(CPEMIs.size());
476 
477  // Do the initial scan of the function, building up information about the
478  // sizes of each block, the location of all the water, and finding all of the
479  // constant pool users.
480  initializeFunctionInfo(CPEMIs);
481  CPEMIs.clear();
482  DEBUG(dumpBBs());
483 
484  /// Remove dead constant pool entries.
485  MadeChange |= removeUnusedCPEntries();
486 
487  // Iteratively place constant pool entries and fix up branches until there
488  // is no change.
489  unsigned NoCPIters = 0, NoBRIters = 0;
490  (void)NoBRIters;
491  while (true) {
492  DEBUG(dbgs() << "Beginning CP iteration #" << NoCPIters << '\n');
493  bool CPChange = false;
494  for (unsigned i = 0, e = CPUsers.size(); i != e; ++i)
495  CPChange |= handleConstantPoolUser(i);
496  if (CPChange && ++NoCPIters > 30)
497  report_fatal_error("Constant Island pass failed to converge!");
498  DEBUG(dumpBBs());
499 
500  // Clear NewWaterList now. If we split a block for branches, it should
501  // appear as "new water" for the next iteration of constant pool placement.
502  NewWaterList.clear();
503 
504  DEBUG(dbgs() << "Beginning BR iteration #" << NoBRIters << '\n');
505  bool BRChange = false;
506  for (unsigned i = 0, e = ImmBranches.size(); i != e; ++i)
507  BRChange |= fixupImmediateBr(ImmBranches[i]);
508  if (BRChange && ++NoBRIters > 30)
509  report_fatal_error("Branch Fix Up pass failed to converge!");
510  DEBUG(dumpBBs());
511  if (!CPChange && !BRChange)
512  break;
513  MadeChange = true;
514  }
515 
516  DEBUG(dbgs() << '\n'; dumpBBs());
517 
518  BBInfo.clear();
519  WaterList.clear();
520  CPUsers.clear();
521  CPEntries.clear();
522  ImmBranches.clear();
523  return MadeChange;
524 }
525 
526 /// doInitialPlacement - Perform the initial placement of the constant pool
527 /// entries. To start with, we put them all at the end of the function.
528 void
529 MipsConstantIslands::doInitialPlacement(std::vector<MachineInstr*> &CPEMIs) {
530  // Create the basic block to hold the CPE's.
531  MachineBasicBlock *BB = MF->CreateMachineBasicBlock();
532  MF->push_back(BB);
533 
534  // MachineConstantPool measures alignment in bytes. We measure in log2(bytes).
535  unsigned MaxAlign = Log2_32(MCP->getConstantPoolAlignment());
536 
537  // Mark the basic block as required by the const-pool.
538  // If AlignConstantIslands isn't set, use 4-byte alignment for everything.
539  BB->setAlignment(AlignConstantIslands ? MaxAlign : 2);
540 
541  // The function needs to be as aligned as the basic blocks. The linker may
542  // move functions around based on their alignment.
543  MF->ensureAlignment(BB->getAlignment());
544 
545  // Order the entries in BB by descending alignment. That ensures correct
546  // alignment of all entries as long as BB is sufficiently aligned. Keep
547  // track of the insertion point for each alignment. We are going to bucket
548  // sort the entries as they are created.
549  SmallVector<MachineBasicBlock::iterator, 8> InsPoint(MaxAlign + 1, BB->end());
550 
551  // Add all of the constants from the constant pool to the end block, use an
552  // identity mapping of CPI's to CPE's.
553  const std::vector<MachineConstantPoolEntry> &CPs = MCP->getConstants();
554 
555  const DataLayout &TD = MF->getDataLayout();
556  for (unsigned i = 0, e = CPs.size(); i != e; ++i) {
557  unsigned Size = TD.getTypeAllocSize(CPs[i].getType());
558  assert(Size >= 4 && "Too small constant pool entry");
559  unsigned Align = CPs[i].getAlignment();
560  assert(isPowerOf2_32(Align) && "Invalid alignment");
561  // Verify that all constant pool entries are a multiple of their alignment.
562  // If not, we would have to pad them out so that instructions stay aligned.
563  assert((Size % Align) == 0 && "CP Entry not multiple of 4 bytes!");
564 
565  // Insert CONSTPOOL_ENTRY before entries with a smaller alignment.
566  unsigned LogAlign = Log2_32(Align);
567  MachineBasicBlock::iterator InsAt = InsPoint[LogAlign];
568 
569  MachineInstr *CPEMI =
570  BuildMI(*BB, InsAt, DebugLoc(), TII->get(Mips::CONSTPOOL_ENTRY))
571  .addImm(i).addConstantPoolIndex(i).addImm(Size);
572 
573  CPEMIs.push_back(CPEMI);
574 
575  // Ensure that future entries with higher alignment get inserted before
576  // CPEMI. This is bucket sort with iterators.
577  for (unsigned a = LogAlign + 1; a <= MaxAlign; ++a)
578  if (InsPoint[a] == InsAt)
579  InsPoint[a] = CPEMI;
580  // Add a new CPEntry, but no corresponding CPUser yet.
581  CPEntries.emplace_back(1, CPEntry(CPEMI, i));
582  ++NumCPEs;
583  DEBUG(dbgs() << "Moved CPI#" << i << " to end of function, size = "
584  << Size << ", align = " << Align <<'\n');
585  }
586  DEBUG(BB->dump());
587 }
588 
589 /// BBHasFallthrough - Return true if the specified basic block can fallthrough
590 /// into the block immediately after it.
592  // Get the next machine basic block in the function.
594  // Can't fall off end of function.
595  if (std::next(MBBI) == MBB->getParent()->end())
596  return false;
597 
598  MachineBasicBlock *NextBB = &*std::next(MBBI);
600  E = MBB->succ_end(); I != E; ++I)
601  if (*I == NextBB)
602  return true;
603 
604  return false;
605 }
606 
607 /// findConstPoolEntry - Given the constpool index and CONSTPOOL_ENTRY MI,
608 /// look up the corresponding CPEntry.
609 MipsConstantIslands::CPEntry
610 *MipsConstantIslands::findConstPoolEntry(unsigned CPI,
611  const MachineInstr *CPEMI) {
612  std::vector<CPEntry> &CPEs = CPEntries[CPI];
613  // Number of entries per constpool index should be small, just do a
614  // linear search.
615  for (unsigned i = 0, e = CPEs.size(); i != e; ++i) {
616  if (CPEs[i].CPEMI == CPEMI)
617  return &CPEs[i];
618  }
619  return nullptr;
620 }
621 
622 /// getCPELogAlign - Returns the required alignment of the constant pool entry
623 /// represented by CPEMI. Alignment is measured in log2(bytes) units.
624 unsigned MipsConstantIslands::getCPELogAlign(const MachineInstr &CPEMI) {
625  assert(CPEMI.getOpcode() == Mips::CONSTPOOL_ENTRY);
626 
627  // Everything is 4-byte aligned unless AlignConstantIslands is set.
629  return 2;
630 
631  unsigned CPI = CPEMI.getOperand(1).getIndex();
632  assert(CPI < MCP->getConstants().size() && "Invalid constant pool index.");
633  unsigned Align = MCP->getConstants()[CPI].getAlignment();
634  assert(isPowerOf2_32(Align) && "Invalid CPE alignment");
635  return Log2_32(Align);
636 }
637 
638 /// initializeFunctionInfo - Do the initial scan of the function, building up
639 /// information about the sizes of each block, the location of all the water,
640 /// and finding all of the constant pool users.
641 void MipsConstantIslands::
642 initializeFunctionInfo(const std::vector<MachineInstr*> &CPEMIs) {
643  BBInfo.clear();
644  BBInfo.resize(MF->getNumBlockIDs());
645 
646  // First thing, compute the size of all basic blocks, and see if the function
647  // has any inline assembly in it. If so, we have to be conservative about
648  // alignment assumptions, as we don't know for sure the size of any
649  // instructions in the inline assembly.
650  for (MachineFunction::iterator I = MF->begin(), E = MF->end(); I != E; ++I)
651  computeBlockSize(&*I);
652 
653  // Compute block offsets.
654  adjustBBOffsetsAfter(&MF->front());
655 
656  // Now go back through the instructions and build up our data structures.
657  for (MachineBasicBlock &MBB : *MF) {
658  // If this block doesn't fall through into the next MBB, then this is
659  // 'water' that a constant pool island could be placed.
660  if (!BBHasFallthrough(&MBB))
661  WaterList.push_back(&MBB);
662  for (MachineInstr &MI : MBB) {
663  if (MI.isDebugValue())
664  continue;
665 
666  int Opc = MI.getOpcode();
667  if (MI.isBranch()) {
668  bool isCond = false;
669  unsigned Bits = 0;
670  unsigned Scale = 1;
671  int UOpc = Opc;
672  switch (Opc) {
673  default:
674  continue; // Ignore other branches for now
675  case Mips::Bimm16:
676  Bits = 11;
677  Scale = 2;
678  isCond = false;
679  break;
680  case Mips::BimmX16:
681  Bits = 16;
682  Scale = 2;
683  isCond = false;
684  break;
685  case Mips::BeqzRxImm16:
686  UOpc=Mips::Bimm16;
687  Bits = 8;
688  Scale = 2;
689  isCond = true;
690  break;
691  case Mips::BeqzRxImmX16:
692  UOpc=Mips::Bimm16;
693  Bits = 16;
694  Scale = 2;
695  isCond = true;
696  break;
697  case Mips::BnezRxImm16:
698  UOpc=Mips::Bimm16;
699  Bits = 8;
700  Scale = 2;
701  isCond = true;
702  break;
703  case Mips::BnezRxImmX16:
704  UOpc=Mips::Bimm16;
705  Bits = 16;
706  Scale = 2;
707  isCond = true;
708  break;
709  case Mips::Bteqz16:
710  UOpc=Mips::Bimm16;
711  Bits = 8;
712  Scale = 2;
713  isCond = true;
714  break;
715  case Mips::BteqzX16:
716  UOpc=Mips::Bimm16;
717  Bits = 16;
718  Scale = 2;
719  isCond = true;
720  break;
721  case Mips::Btnez16:
722  UOpc=Mips::Bimm16;
723  Bits = 8;
724  Scale = 2;
725  isCond = true;
726  break;
727  case Mips::BtnezX16:
728  UOpc=Mips::Bimm16;
729  Bits = 16;
730  Scale = 2;
731  isCond = true;
732  break;
733  }
734  // Record this immediate branch.
735  unsigned MaxOffs = ((1 << (Bits-1))-1) * Scale;
736  ImmBranches.push_back(ImmBranch(&MI, MaxOffs, isCond, UOpc));
737  }
738 
739  if (Opc == Mips::CONSTPOOL_ENTRY)
740  continue;
741 
742  // Scan the instructions for constant pool operands.
743  for (unsigned op = 0, e = MI.getNumOperands(); op != e; ++op)
744  if (MI.getOperand(op).isCPI()) {
745  // We found one. The addressing mode tells us the max displacement
746  // from the PC that this instruction permits.
747 
748  // Basic size info comes from the TSFlags field.
749  unsigned Bits = 0;
750  unsigned Scale = 1;
751  bool NegOk = false;
752  unsigned LongFormBits = 0;
753  unsigned LongFormScale = 0;
754  unsigned LongFormOpcode = 0;
755  switch (Opc) {
756  default:
757  llvm_unreachable("Unknown addressing mode for CP reference!");
758  case Mips::LwRxPcTcp16:
759  Bits = 8;
760  Scale = 4;
761  LongFormOpcode = Mips::LwRxPcTcpX16;
762  LongFormBits = 14;
763  LongFormScale = 1;
764  break;
765  case Mips::LwRxPcTcpX16:
766  Bits = 14;
767  Scale = 1;
768  NegOk = true;
769  break;
770  }
771  // Remember that this is a user of a CP entry.
772  unsigned CPI = MI.getOperand(op).getIndex();
773  MachineInstr *CPEMI = CPEMIs[CPI];
774  unsigned MaxOffs = ((1 << Bits)-1) * Scale;
775  unsigned LongFormMaxOffs = ((1 << LongFormBits)-1) * LongFormScale;
776  CPUsers.push_back(CPUser(&MI, CPEMI, MaxOffs, NegOk, LongFormMaxOffs,
777  LongFormOpcode));
778 
779  // Increment corresponding CPEntry reference count.
780  CPEntry *CPE = findConstPoolEntry(CPI, CPEMI);
781  assert(CPE && "Cannot find a corresponding CPEntry!");
782  CPE->RefCount++;
783 
784  // Instructions can only use one CP entry, don't bother scanning the
785  // rest of the operands.
786  break;
787  }
788  }
789  }
790 }
791 
792 /// computeBlockSize - Compute the size and some alignment information for MBB.
793 /// This function updates BBInfo directly.
795  BasicBlockInfo &BBI = BBInfo[MBB->getNumber()];
796  BBI.Size = 0;
797 
798  for (const MachineInstr &MI : *MBB)
799  BBI.Size += TII->getInstSizeInBytes(MI);
800 }
801 
802 /// getOffsetOf - Return the current offset of the specified machine instruction
803 /// from the start of the function. This offset changes as stuff is moved
804 /// around inside the function.
805 unsigned MipsConstantIslands::getOffsetOf(MachineInstr *MI) const {
806  MachineBasicBlock *MBB = MI->getParent();
807 
808  // The offset is composed of two things: the sum of the sizes of all MBB's
809  // before this instruction's block, and the offset from the start of the block
810  // it is in.
811  unsigned Offset = BBInfo[MBB->getNumber()].Offset;
812 
813  // Sum instructions before MI in MBB.
814  for (MachineBasicBlock::iterator I = MBB->begin(); &*I != MI; ++I) {
815  assert(I != MBB->end() && "Didn't find MI in its own basic block?");
816  Offset += TII->getInstSizeInBytes(*I);
817  }
818  return Offset;
819 }
820 
821 /// CompareMBBNumbers - Little predicate function to sort the WaterList by MBB
822 /// ID.
823 static bool CompareMBBNumbers(const MachineBasicBlock *LHS,
824  const MachineBasicBlock *RHS) {
825  return LHS->getNumber() < RHS->getNumber();
826 }
827 
828 /// updateForInsertedWaterBlock - When a block is newly inserted into the
829 /// machine function, it upsets all of the block numbers. Renumber the blocks
830 /// and update the arrays that parallel this numbering.
831 void MipsConstantIslands::updateForInsertedWaterBlock
832  (MachineBasicBlock *NewBB) {
833  // Renumber the MBB's to keep them consecutive.
834  NewBB->getParent()->RenumberBlocks(NewBB);
835 
836  // Insert an entry into BBInfo to align it properly with the (newly
837  // renumbered) block numbers.
838  BBInfo.insert(BBInfo.begin() + NewBB->getNumber(), BasicBlockInfo());
839 
840  // Next, update WaterList. Specifically, we need to add NewMBB as having
841  // available water after it.
842  water_iterator IP =
843  std::lower_bound(WaterList.begin(), WaterList.end(), NewBB,
845  WaterList.insert(IP, NewBB);
846 }
847 
848 unsigned MipsConstantIslands::getUserOffset(CPUser &U) const {
849  return getOffsetOf(U.MI);
850 }
851 
852 /// Split the basic block containing MI into two blocks, which are joined by
853 /// an unconditional branch. Update data structures and renumber blocks to
854 /// account for this change and returns the newly created block.
856 MipsConstantIslands::splitBlockBeforeInstr(MachineInstr &MI) {
857  MachineBasicBlock *OrigBB = MI.getParent();
858 
859  // Create a new MBB for the code after the OrigBB.
860  MachineBasicBlock *NewBB =
861  MF->CreateMachineBasicBlock(OrigBB->getBasicBlock());
862  MachineFunction::iterator MBBI = ++OrigBB->getIterator();
863  MF->insert(MBBI, NewBB);
864 
865  // Splice the instructions starting with MI over to NewBB.
866  NewBB->splice(NewBB->end(), OrigBB, MI, OrigBB->end());
867 
868  // Add an unconditional branch from OrigBB to NewBB.
869  // Note the new unconditional branch is not being recorded.
870  // There doesn't seem to be meaningful DebugInfo available; this doesn't
871  // correspond to anything in the source.
872  BuildMI(OrigBB, DebugLoc(), TII->get(Mips::Bimm16)).addMBB(NewBB);
873  ++NumSplit;
874 
875  // Update the CFG. All succs of OrigBB are now succs of NewBB.
876  NewBB->transferSuccessors(OrigBB);
877 
878  // OrigBB branches to NewBB.
879  OrigBB->addSuccessor(NewBB);
880 
881  // Update internal data structures to account for the newly inserted MBB.
882  // This is almost the same as updateForInsertedWaterBlock, except that
883  // the Water goes after OrigBB, not NewBB.
884  MF->RenumberBlocks(NewBB);
885 
886  // Insert an entry into BBInfo to align it properly with the (newly
887  // renumbered) block numbers.
888  BBInfo.insert(BBInfo.begin() + NewBB->getNumber(), BasicBlockInfo());
889 
890  // Next, update WaterList. Specifically, we need to add OrigMBB as having
891  // available water after it (but not if it's already there, which happens
892  // when splitting before a conditional branch that is followed by an
893  // unconditional branch - in that case we want to insert NewBB).
894  water_iterator IP =
895  std::lower_bound(WaterList.begin(), WaterList.end(), OrigBB,
897  MachineBasicBlock* WaterBB = *IP;
898  if (WaterBB == OrigBB)
899  WaterList.insert(std::next(IP), NewBB);
900  else
901  WaterList.insert(IP, OrigBB);
902  NewWaterList.insert(OrigBB);
903 
904  // Figure out how large the OrigBB is. As the first half of the original
905  // block, it cannot contain a tablejump. The size includes
906  // the new jump we added. (It should be possible to do this without
907  // recounting everything, but it's very confusing, and this is rarely
908  // executed.)
909  computeBlockSize(OrigBB);
910 
911  // Figure out how large the NewMBB is. As the second half of the original
912  // block, it may contain a tablejump.
913  computeBlockSize(NewBB);
914 
915  // All BBOffsets following these blocks must be modified.
916  adjustBBOffsetsAfter(OrigBB);
917 
918  return NewBB;
919 }
920 
921 /// isOffsetInRange - Checks whether UserOffset (the location of a constant pool
922 /// reference) is within MaxDisp of TrialOffset (a proposed location of a
923 /// constant pool entry).
924 bool MipsConstantIslands::isOffsetInRange(unsigned UserOffset,
925  unsigned TrialOffset, unsigned MaxDisp,
926  bool NegativeOK) {
927  if (UserOffset <= TrialOffset) {
928  // User before the Trial.
929  if (TrialOffset - UserOffset <= MaxDisp)
930  return true;
931  } else if (NegativeOK) {
932  if (UserOffset - TrialOffset <= MaxDisp)
933  return true;
934  }
935  return false;
936 }
937 
938 /// isWaterInRange - Returns true if a CPE placed after the specified
939 /// Water (a basic block) will be in range for the specific MI.
940 ///
941 /// Compute how much the function will grow by inserting a CPE after Water.
942 bool MipsConstantIslands::isWaterInRange(unsigned UserOffset,
943  MachineBasicBlock* Water, CPUser &U,
944  unsigned &Growth) {
945  unsigned CPELogAlign = getCPELogAlign(*U.CPEMI);
946  unsigned CPEOffset = BBInfo[Water->getNumber()].postOffset(CPELogAlign);
947  unsigned NextBlockOffset, NextBlockAlignment;
948  MachineFunction::const_iterator NextBlock = ++Water->getIterator();
949  if (NextBlock == MF->end()) {
950  NextBlockOffset = BBInfo[Water->getNumber()].postOffset();
951  NextBlockAlignment = 0;
952  } else {
953  NextBlockOffset = BBInfo[NextBlock->getNumber()].Offset;
954  NextBlockAlignment = NextBlock->getAlignment();
955  }
956  unsigned Size = U.CPEMI->getOperand(2).getImm();
957  unsigned CPEEnd = CPEOffset + Size;
958 
959  // The CPE may be able to hide in the alignment padding before the next
960  // block. It may also cause more padding to be required if it is more aligned
961  // that the next block.
962  if (CPEEnd > NextBlockOffset) {
963  Growth = CPEEnd - NextBlockOffset;
964  // Compute the padding that would go at the end of the CPE to align the next
965  // block.
966  Growth += OffsetToAlignment(CPEEnd, 1ULL << NextBlockAlignment);
967 
968  // If the CPE is to be inserted before the instruction, that will raise
969  // the offset of the instruction. Also account for unknown alignment padding
970  // in blocks between CPE and the user.
971  if (CPEOffset < UserOffset)
972  UserOffset += Growth;
973  } else
974  // CPE fits in existing padding.
975  Growth = 0;
976 
977  return isOffsetInRange(UserOffset, CPEOffset, U);
978 }
979 
980 /// isCPEntryInRange - Returns true if the distance between specific MI and
981 /// specific ConstPool entry instruction can fit in MI's displacement field.
982 bool MipsConstantIslands::isCPEntryInRange
983  (MachineInstr *MI, unsigned UserOffset,
984  MachineInstr *CPEMI, unsigned MaxDisp,
985  bool NegOk, bool DoDump) {
986  unsigned CPEOffset = getOffsetOf(CPEMI);
987 
988  if (DoDump) {
989  DEBUG({
990  unsigned Block = MI->getParent()->getNumber();
991  const BasicBlockInfo &BBI = BBInfo[Block];
992  dbgs() << "User of CPE#" << CPEMI->getOperand(0).getImm()
993  << " max delta=" << MaxDisp
994  << format(" insn address=%#x", UserOffset)
995  << " in BB#" << Block << ": "
996  << format("%#x-%x\t", BBI.Offset, BBI.postOffset()) << *MI
997  << format("CPE address=%#x offset=%+d: ", CPEOffset,
998  int(CPEOffset-UserOffset));
999  });
1000  }
1001 
1002  return isOffsetInRange(UserOffset, CPEOffset, MaxDisp, NegOk);
1003 }
1004 
1005 #ifndef NDEBUG
1006 /// BBIsJumpedOver - Return true of the specified basic block's only predecessor
1007 /// unconditionally branches to its only successor.
1009  if (MBB->pred_size() != 1 || MBB->succ_size() != 1)
1010  return false;
1011  MachineBasicBlock *Succ = *MBB->succ_begin();
1012  MachineBasicBlock *Pred = *MBB->pred_begin();
1013  MachineInstr *PredMI = &Pred->back();
1014  if (PredMI->getOpcode() == Mips::Bimm16)
1015  return PredMI->getOperand(0).getMBB() == Succ;
1016  return false;
1017 }
1018 #endif
1019 
1020 void MipsConstantIslands::adjustBBOffsetsAfter(MachineBasicBlock *BB) {
1021  unsigned BBNum = BB->getNumber();
1022  for(unsigned i = BBNum + 1, e = MF->getNumBlockIDs(); i < e; ++i) {
1023  // Get the offset and known bits at the end of the layout predecessor.
1024  // Include the alignment of the current block.
1025  unsigned Offset = BBInfo[i - 1].Offset + BBInfo[i - 1].Size;
1026  BBInfo[i].Offset = Offset;
1027  }
1028 }
1029 
1030 /// decrementCPEReferenceCount - find the constant pool entry with index CPI
1031 /// and instruction CPEMI, and decrement its refcount. If the refcount
1032 /// becomes 0 remove the entry and instruction. Returns true if we removed
1033 /// the entry, false if we didn't.
1034 bool MipsConstantIslands::decrementCPEReferenceCount(unsigned CPI,
1035  MachineInstr *CPEMI) {
1036  // Find the old entry. Eliminate it if it is no longer used.
1037  CPEntry *CPE = findConstPoolEntry(CPI, CPEMI);
1038  assert(CPE && "Unexpected!");
1039  if (--CPE->RefCount == 0) {
1040  removeDeadCPEMI(CPEMI);
1041  CPE->CPEMI = nullptr;
1042  --NumCPEs;
1043  return true;
1044  }
1045  return false;
1046 }
1047 
1048 /// LookForCPEntryInRange - see if the currently referenced CPE is in range;
1049 /// if not, see if an in-range clone of the CPE is in range, and if so,
1050 /// change the data structures so the user references the clone. Returns:
1051 /// 0 = no existing entry found
1052 /// 1 = entry found, and there were no code insertions or deletions
1053 /// 2 = entry found, and there were code insertions or deletions
1054 int MipsConstantIslands::findInRangeCPEntry(CPUser& U, unsigned UserOffset)
1055 {
1056  MachineInstr *UserMI = U.MI;
1057  MachineInstr *CPEMI = U.CPEMI;
1058 
1059  // Check to see if the CPE is already in-range.
1060  if (isCPEntryInRange(UserMI, UserOffset, CPEMI, U.getMaxDisp(), U.NegOk,
1061  true)) {
1062  DEBUG(dbgs() << "In range\n");
1063  return 1;
1064  }
1065 
1066  // No. Look for previously created clones of the CPE that are in range.
1067  unsigned CPI = CPEMI->getOperand(1).getIndex();
1068  std::vector<CPEntry> &CPEs = CPEntries[CPI];
1069  for (unsigned i = 0, e = CPEs.size(); i != e; ++i) {
1070  // We already tried this one
1071  if (CPEs[i].CPEMI == CPEMI)
1072  continue;
1073  // Removing CPEs can leave empty entries, skip
1074  if (CPEs[i].CPEMI == nullptr)
1075  continue;
1076  if (isCPEntryInRange(UserMI, UserOffset, CPEs[i].CPEMI, U.getMaxDisp(),
1077  U.NegOk)) {
1078  DEBUG(dbgs() << "Replacing CPE#" << CPI << " with CPE#"
1079  << CPEs[i].CPI << "\n");
1080  // Point the CPUser node to the replacement
1081  U.CPEMI = CPEs[i].CPEMI;
1082  // Change the CPI in the instruction operand to refer to the clone.
1083  for (unsigned j = 0, e = UserMI->getNumOperands(); j != e; ++j)
1084  if (UserMI->getOperand(j).isCPI()) {
1085  UserMI->getOperand(j).setIndex(CPEs[i].CPI);
1086  break;
1087  }
1088  // Adjust the refcount of the clone...
1089  CPEs[i].RefCount++;
1090  // ...and the original. If we didn't remove the old entry, none of the
1091  // addresses changed, so we don't need another pass.
1092  return decrementCPEReferenceCount(CPI, CPEMI) ? 2 : 1;
1093  }
1094  }
1095  return 0;
1096 }
1097 
1098 /// LookForCPEntryInRange - see if the currently referenced CPE is in range;
1099 /// This version checks if the longer form of the instruction can be used to
1100 /// to satisfy things.
1101 /// if not, see if an in-range clone of the CPE is in range, and if so,
1102 /// change the data structures so the user references the clone. Returns:
1103 /// 0 = no existing entry found
1104 /// 1 = entry found, and there were no code insertions or deletions
1105 /// 2 = entry found, and there were code insertions or deletions
1106 int MipsConstantIslands::findLongFormInRangeCPEntry
1107  (CPUser& U, unsigned UserOffset)
1108 {
1109  MachineInstr *UserMI = U.MI;
1110  MachineInstr *CPEMI = U.CPEMI;
1111 
1112  // Check to see if the CPE is already in-range.
1113  if (isCPEntryInRange(UserMI, UserOffset, CPEMI,
1114  U.getLongFormMaxDisp(), U.NegOk,
1115  true)) {
1116  DEBUG(dbgs() << "In range\n");
1117  UserMI->setDesc(TII->get(U.getLongFormOpcode()));
1118  U.setMaxDisp(U.getLongFormMaxDisp());
1119  return 2; // instruction is longer length now
1120  }
1121 
1122  // No. Look for previously created clones of the CPE that are in range.
1123  unsigned CPI = CPEMI->getOperand(1).getIndex();
1124  std::vector<CPEntry> &CPEs = CPEntries[CPI];
1125  for (unsigned i = 0, e = CPEs.size(); i != e; ++i) {
1126  // We already tried this one
1127  if (CPEs[i].CPEMI == CPEMI)
1128  continue;
1129  // Removing CPEs can leave empty entries, skip
1130  if (CPEs[i].CPEMI == nullptr)
1131  continue;
1132  if (isCPEntryInRange(UserMI, UserOffset, CPEs[i].CPEMI,
1133  U.getLongFormMaxDisp(), U.NegOk)) {
1134  DEBUG(dbgs() << "Replacing CPE#" << CPI << " with CPE#"
1135  << CPEs[i].CPI << "\n");
1136  // Point the CPUser node to the replacement
1137  U.CPEMI = CPEs[i].CPEMI;
1138  // Change the CPI in the instruction operand to refer to the clone.
1139  for (unsigned j = 0, e = UserMI->getNumOperands(); j != e; ++j)
1140  if (UserMI->getOperand(j).isCPI()) {
1141  UserMI->getOperand(j).setIndex(CPEs[i].CPI);
1142  break;
1143  }
1144  // Adjust the refcount of the clone...
1145  CPEs[i].RefCount++;
1146  // ...and the original. If we didn't remove the old entry, none of the
1147  // addresses changed, so we don't need another pass.
1148  return decrementCPEReferenceCount(CPI, CPEMI) ? 2 : 1;
1149  }
1150  }
1151  return 0;
1152 }
1153 
1154 /// getUnconditionalBrDisp - Returns the maximum displacement that can fit in
1155 /// the specific unconditional branch instruction.
1156 static inline unsigned getUnconditionalBrDisp(int Opc) {
1157  switch (Opc) {
1158  case Mips::Bimm16:
1159  return ((1<<10)-1)*2;
1160  case Mips::BimmX16:
1161  return ((1<<16)-1)*2;
1162  default:
1163  break;
1164  }
1165  return ((1<<16)-1)*2;
1166 }
1167 
1168 /// findAvailableWater - Look for an existing entry in the WaterList in which
1169 /// we can place the CPE referenced from U so it's within range of U's MI.
1170 /// Returns true if found, false if not. If it returns true, WaterIter
1171 /// is set to the WaterList entry.
1172 /// To ensure that this pass
1173 /// terminates, the CPE location for a particular CPUser is only allowed to
1174 /// move to a lower address, so search backward from the end of the list and
1175 /// prefer the first water that is in range.
1176 bool MipsConstantIslands::findAvailableWater(CPUser &U, unsigned UserOffset,
1177  water_iterator &WaterIter) {
1178  if (WaterList.empty())
1179  return false;
1180 
1181  unsigned BestGrowth = ~0u;
1182  for (water_iterator IP = std::prev(WaterList.end()), B = WaterList.begin();;
1183  --IP) {
1184  MachineBasicBlock* WaterBB = *IP;
1185  // Check if water is in range and is either at a lower address than the
1186  // current "high water mark" or a new water block that was created since
1187  // the previous iteration by inserting an unconditional branch. In the
1188  // latter case, we want to allow resetting the high water mark back to
1189  // this new water since we haven't seen it before. Inserting branches
1190  // should be relatively uncommon and when it does happen, we want to be
1191  // sure to take advantage of it for all the CPEs near that block, so that
1192  // we don't insert more branches than necessary.
1193  unsigned Growth;
1194  if (isWaterInRange(UserOffset, WaterBB, U, Growth) &&
1195  (WaterBB->getNumber() < U.HighWaterMark->getNumber() ||
1196  NewWaterList.count(WaterBB)) && Growth < BestGrowth) {
1197  // This is the least amount of required padding seen so far.
1198  BestGrowth = Growth;
1199  WaterIter = IP;
1200  DEBUG(dbgs() << "Found water after BB#" << WaterBB->getNumber()
1201  << " Growth=" << Growth << '\n');
1202 
1203  // Keep looking unless it is perfect.
1204  if (BestGrowth == 0)
1205  return true;
1206  }
1207  if (IP == B)
1208  break;
1209  }
1210  return BestGrowth != ~0u;
1211 }
1212 
1213 /// createNewWater - No existing WaterList entry will work for
1214 /// CPUsers[CPUserIndex], so create a place to put the CPE. The end of the
1215 /// block is used if in range, and the conditional branch munged so control
1216 /// flow is correct. Otherwise the block is split to create a hole with an
1217 /// unconditional branch around it. In either case NewMBB is set to a
1218 /// block following which the new island can be inserted (the WaterList
1219 /// is not adjusted).
1220 void MipsConstantIslands::createNewWater(unsigned CPUserIndex,
1221  unsigned UserOffset,
1222  MachineBasicBlock *&NewMBB) {
1223  CPUser &U = CPUsers[CPUserIndex];
1224  MachineInstr *UserMI = U.MI;
1225  MachineInstr *CPEMI = U.CPEMI;
1226  unsigned CPELogAlign = getCPELogAlign(*CPEMI);
1227  MachineBasicBlock *UserMBB = UserMI->getParent();
1228  const BasicBlockInfo &UserBBI = BBInfo[UserMBB->getNumber()];
1229 
1230  // If the block does not end in an unconditional branch already, and if the
1231  // end of the block is within range, make new water there.
1232  if (BBHasFallthrough(UserMBB)) {
1233  // Size of branch to insert.
1234  unsigned Delta = 2;
1235  // Compute the offset where the CPE will begin.
1236  unsigned CPEOffset = UserBBI.postOffset(CPELogAlign) + Delta;
1237 
1238  if (isOffsetInRange(UserOffset, CPEOffset, U)) {
1239  DEBUG(dbgs() << "Split at end of BB#" << UserMBB->getNumber()
1240  << format(", expected CPE offset %#x\n", CPEOffset));
1241  NewMBB = &*++UserMBB->getIterator();
1242  // Add an unconditional branch from UserMBB to fallthrough block. Record
1243  // it for branch lengthening; this new branch will not get out of range,
1244  // but if the preceding conditional branch is out of range, the targets
1245  // will be exchanged, and the altered branch may be out of range, so the
1246  // machinery has to know about it.
1247  int UncondBr = Mips::Bimm16;
1248  BuildMI(UserMBB, DebugLoc(), TII->get(UncondBr)).addMBB(NewMBB);
1249  unsigned MaxDisp = getUnconditionalBrDisp(UncondBr);
1250  ImmBranches.push_back(ImmBranch(&UserMBB->back(),
1251  MaxDisp, false, UncondBr));
1252  BBInfo[UserMBB->getNumber()].Size += Delta;
1253  adjustBBOffsetsAfter(UserMBB);
1254  return;
1255  }
1256  }
1257 
1258  // What a big block. Find a place within the block to split it.
1259 
1260  // Try to split the block so it's fully aligned. Compute the latest split
1261  // point where we can add a 4-byte branch instruction, and then align to
1262  // LogAlign which is the largest possible alignment in the function.
1263  unsigned LogAlign = MF->getAlignment();
1264  assert(LogAlign >= CPELogAlign && "Over-aligned constant pool entry");
1265  unsigned BaseInsertOffset = UserOffset + U.getMaxDisp();
1266  DEBUG(dbgs() << format("Split in middle of big block before %#x",
1267  BaseInsertOffset));
1268 
1269  // The 4 in the following is for the unconditional branch we'll be inserting
1270  // Alignment of the island is handled
1271  // inside isOffsetInRange.
1272  BaseInsertOffset -= 4;
1273 
1274  DEBUG(dbgs() << format(", adjusted to %#x", BaseInsertOffset)
1275  << " la=" << LogAlign << '\n');
1276 
1277  // This could point off the end of the block if we've already got constant
1278  // pool entries following this block; only the last one is in the water list.
1279  // Back past any possible branches (allow for a conditional and a maximally
1280  // long unconditional).
1281  if (BaseInsertOffset + 8 >= UserBBI.postOffset()) {
1282  BaseInsertOffset = UserBBI.postOffset() - 8;
1283  DEBUG(dbgs() << format("Move inside block: %#x\n", BaseInsertOffset));
1284  }
1285  unsigned EndInsertOffset = BaseInsertOffset + 4 +
1286  CPEMI->getOperand(2).getImm();
1287  MachineBasicBlock::iterator MI = UserMI;
1288  ++MI;
1289  unsigned CPUIndex = CPUserIndex+1;
1290  unsigned NumCPUsers = CPUsers.size();
1291  //MachineInstr *LastIT = 0;
1292  for (unsigned Offset = UserOffset + TII->getInstSizeInBytes(*UserMI);
1293  Offset < BaseInsertOffset;
1294  Offset += TII->getInstSizeInBytes(*MI), MI = std::next(MI)) {
1295  assert(MI != UserMBB->end() && "Fell off end of block");
1296  if (CPUIndex < NumCPUsers && CPUsers[CPUIndex].MI == MI) {
1297  CPUser &U = CPUsers[CPUIndex];
1298  if (!isOffsetInRange(Offset, EndInsertOffset, U)) {
1299  // Shift intertion point by one unit of alignment so it is within reach.
1300  BaseInsertOffset -= 1u << LogAlign;
1301  EndInsertOffset -= 1u << LogAlign;
1302  }
1303  // This is overly conservative, as we don't account for CPEMIs being
1304  // reused within the block, but it doesn't matter much. Also assume CPEs
1305  // are added in order with alignment padding. We may eventually be able
1306  // to pack the aligned CPEs better.
1307  EndInsertOffset += U.CPEMI->getOperand(2).getImm();
1308  CPUIndex++;
1309  }
1310  }
1311 
1312  NewMBB = splitBlockBeforeInstr(*--MI);
1313 }
1314 
1315 /// handleConstantPoolUser - Analyze the specified user, checking to see if it
1316 /// is out-of-range. If so, pick up the constant pool value and move it some
1317 /// place in-range. Return true if we changed any addresses (thus must run
1318 /// another pass of branch lengthening), false otherwise.
1319 bool MipsConstantIslands::handleConstantPoolUser(unsigned CPUserIndex) {
1320  CPUser &U = CPUsers[CPUserIndex];
1321  MachineInstr *UserMI = U.MI;
1322  MachineInstr *CPEMI = U.CPEMI;
1323  unsigned CPI = CPEMI->getOperand(1).getIndex();
1324  unsigned Size = CPEMI->getOperand(2).getImm();
1325  // Compute this only once, it's expensive.
1326  unsigned UserOffset = getUserOffset(U);
1327 
1328  // See if the current entry is within range, or there is a clone of it
1329  // in range.
1330  int result = findInRangeCPEntry(U, UserOffset);
1331  if (result==1) return false;
1332  else if (result==2) return true;
1333 
1334  // Look for water where we can place this CPE.
1335  MachineBasicBlock *NewIsland = MF->CreateMachineBasicBlock();
1336  MachineBasicBlock *NewMBB;
1337  water_iterator IP;
1338  if (findAvailableWater(U, UserOffset, IP)) {
1339  DEBUG(dbgs() << "Found water in range\n");
1340  MachineBasicBlock *WaterBB = *IP;
1341 
1342  // If the original WaterList entry was "new water" on this iteration,
1343  // propagate that to the new island. This is just keeping NewWaterList
1344  // updated to match the WaterList, which will be updated below.
1345  if (NewWaterList.erase(WaterBB))
1346  NewWaterList.insert(NewIsland);
1347 
1348  // The new CPE goes before the following block (NewMBB).
1349  NewMBB = &*++WaterBB->getIterator();
1350  } else {
1351  // No water found.
1352  // we first see if a longer form of the instrucion could have reached
1353  // the constant. in that case we won't bother to split
1354  if (!NoLoadRelaxation) {
1355  result = findLongFormInRangeCPEntry(U, UserOffset);
1356  if (result != 0) return true;
1357  }
1358  DEBUG(dbgs() << "No water found\n");
1359  createNewWater(CPUserIndex, UserOffset, NewMBB);
1360 
1361  // splitBlockBeforeInstr adds to WaterList, which is important when it is
1362  // called while handling branches so that the water will be seen on the
1363  // next iteration for constant pools, but in this context, we don't want
1364  // it. Check for this so it will be removed from the WaterList.
1365  // Also remove any entry from NewWaterList.
1366  MachineBasicBlock *WaterBB = &*--NewMBB->getIterator();
1367  IP = llvm::find(WaterList, WaterBB);
1368  if (IP != WaterList.end())
1369  NewWaterList.erase(WaterBB);
1370 
1371  // We are adding new water. Update NewWaterList.
1372  NewWaterList.insert(NewIsland);
1373  }
1374 
1375  // Remove the original WaterList entry; we want subsequent insertions in
1376  // this vicinity to go after the one we're about to insert. This
1377  // considerably reduces the number of times we have to move the same CPE
1378  // more than once and is also important to ensure the algorithm terminates.
1379  if (IP != WaterList.end())
1380  WaterList.erase(IP);
1381 
1382  // Okay, we know we can put an island before NewMBB now, do it!
1383  MF->insert(NewMBB->getIterator(), NewIsland);
1384 
1385  // Update internal data structures to account for the newly inserted MBB.
1386  updateForInsertedWaterBlock(NewIsland);
1387 
1388  // Decrement the old entry, and remove it if refcount becomes 0.
1389  decrementCPEReferenceCount(CPI, CPEMI);
1390 
1391  // No existing clone of this CPE is within range.
1392  // We will be generating a new clone. Get a UID for it.
1393  unsigned ID = createPICLabelUId();
1394 
1395  // Now that we have an island to add the CPE to, clone the original CPE and
1396  // add it to the island.
1397  U.HighWaterMark = NewIsland;
1398  U.CPEMI = BuildMI(NewIsland, DebugLoc(), TII->get(Mips::CONSTPOOL_ENTRY))
1399  .addImm(ID).addConstantPoolIndex(CPI).addImm(Size);
1400  CPEntries[CPI].push_back(CPEntry(U.CPEMI, ID, 1));
1401  ++NumCPEs;
1402 
1403  // Mark the basic block as aligned as required by the const-pool entry.
1404  NewIsland->setAlignment(getCPELogAlign(*U.CPEMI));
1405 
1406  // Increase the size of the island block to account for the new entry.
1407  BBInfo[NewIsland->getNumber()].Size += Size;
1408  adjustBBOffsetsAfter(&*--NewIsland->getIterator());
1409 
1410  // Finally, change the CPI in the instruction operand to be ID.
1411  for (unsigned i = 0, e = UserMI->getNumOperands(); i != e; ++i)
1412  if (UserMI->getOperand(i).isCPI()) {
1413  UserMI->getOperand(i).setIndex(ID);
1414  break;
1415  }
1416 
1417  DEBUG(dbgs() << " Moved CPE to #" << ID << " CPI=" << CPI
1418  << format(" offset=%#x\n", BBInfo[NewIsland->getNumber()].Offset));
1419 
1420  return true;
1421 }
1422 
1423 /// removeDeadCPEMI - Remove a dead constant pool entry instruction. Update
1424 /// sizes and offsets of impacted basic blocks.
1425 void MipsConstantIslands::removeDeadCPEMI(MachineInstr *CPEMI) {
1426  MachineBasicBlock *CPEBB = CPEMI->getParent();
1427  unsigned Size = CPEMI->getOperand(2).getImm();
1428  CPEMI->eraseFromParent();
1429  BBInfo[CPEBB->getNumber()].Size -= Size;
1430  // All succeeding offsets have the current size value added in, fix this.
1431  if (CPEBB->empty()) {
1432  BBInfo[CPEBB->getNumber()].Size = 0;
1433 
1434  // This block no longer needs to be aligned.
1435  CPEBB->setAlignment(0);
1436  } else
1437  // Entries are sorted by descending alignment, so realign from the front.
1438  CPEBB->setAlignment(getCPELogAlign(*CPEBB->begin()));
1439 
1440  adjustBBOffsetsAfter(CPEBB);
1441  // An island has only one predecessor BB and one successor BB. Check if
1442  // this BB's predecessor jumps directly to this BB's successor. This
1443  // shouldn't happen currently.
1444  assert(!BBIsJumpedOver(CPEBB) && "How did this happen?");
1445  // FIXME: remove the empty blocks after all the work is done?
1446 }
1447 
1448 /// removeUnusedCPEntries - Remove constant pool entries whose refcounts
1449 /// are zero.
1450 bool MipsConstantIslands::removeUnusedCPEntries() {
1451  unsigned MadeChange = false;
1452  for (unsigned i = 0, e = CPEntries.size(); i != e; ++i) {
1453  std::vector<CPEntry> &CPEs = CPEntries[i];
1454  for (unsigned j = 0, ee = CPEs.size(); j != ee; ++j) {
1455  if (CPEs[j].RefCount == 0 && CPEs[j].CPEMI) {
1456  removeDeadCPEMI(CPEs[j].CPEMI);
1457  CPEs[j].CPEMI = nullptr;
1458  MadeChange = true;
1459  }
1460  }
1461  }
1462  return MadeChange;
1463 }
1464 
1465 /// isBBInRange - Returns true if the distance between specific MI and
1466 /// specific BB can fit in MI's displacement field.
1467 bool MipsConstantIslands::isBBInRange
1468  (MachineInstr *MI,MachineBasicBlock *DestBB, unsigned MaxDisp) {
1469  unsigned PCAdj = 4;
1470  unsigned BrOffset = getOffsetOf(MI) + PCAdj;
1471  unsigned DestOffset = BBInfo[DestBB->getNumber()].Offset;
1472 
1473  DEBUG(dbgs() << "Branch of destination BB#" << DestBB->getNumber()
1474  << " from BB#" << MI->getParent()->getNumber()
1475  << " max delta=" << MaxDisp
1476  << " from " << getOffsetOf(MI) << " to " << DestOffset
1477  << " offset " << int(DestOffset-BrOffset) << "\t" << *MI);
1478 
1479  if (BrOffset <= DestOffset) {
1480  // Branch before the Dest.
1481  if (DestOffset-BrOffset <= MaxDisp)
1482  return true;
1483  } else {
1484  if (BrOffset-DestOffset <= MaxDisp)
1485  return true;
1486  }
1487  return false;
1488 }
1489 
1490 /// fixupImmediateBr - Fix up an immediate branch whose destination is too far
1491 /// away to fit in its displacement field.
1492 bool MipsConstantIslands::fixupImmediateBr(ImmBranch &Br) {
1493  MachineInstr *MI = Br.MI;
1494  unsigned TargetOperand = branchTargetOperand(MI);
1495  MachineBasicBlock *DestBB = MI->getOperand(TargetOperand).getMBB();
1496 
1497  // Check to see if the DestBB is already in-range.
1498  if (isBBInRange(MI, DestBB, Br.MaxDisp))
1499  return false;
1500 
1501  if (!Br.isCond)
1502  return fixupUnconditionalBr(Br);
1503  return fixupConditionalBr(Br);
1504 }
1505 
1506 /// fixupUnconditionalBr - Fix up an unconditional branch whose destination is
1507 /// too far away to fit in its displacement field. If the LR register has been
1508 /// spilled in the epilogue, then we can use BL to implement a far jump.
1509 /// Otherwise, add an intermediate branch instruction to a branch.
1510 bool
1511 MipsConstantIslands::fixupUnconditionalBr(ImmBranch &Br) {
1512  MachineInstr *MI = Br.MI;
1513  MachineBasicBlock *MBB = MI->getParent();
1514  MachineBasicBlock *DestBB = MI->getOperand(0).getMBB();
1515  // Use BL to implement far jump.
1516  unsigned BimmX16MaxDisp = ((1 << 16)-1) * 2;
1517  if (isBBInRange(MI, DestBB, BimmX16MaxDisp)) {
1518  Br.MaxDisp = BimmX16MaxDisp;
1519  MI->setDesc(TII->get(Mips::BimmX16));
1520  }
1521  else {
1522  // need to give the math a more careful look here
1523  // this is really a segment address and not
1524  // a PC relative address. FIXME. But I think that
1525  // just reducing the bits by 1 as I've done is correct.
1526  // The basic block we are branching too much be longword aligned.
1527  // we know that RA is saved because we always save it right now.
1528  // this requirement will be relaxed later but we also have an alternate
1529  // way to implement this that I will implement that does not need jal.
1530  // We should have a way to back out this alignment restriction if we "can" later.
1531  // but it is not harmful.
1532  //
1533  DestBB->setAlignment(2);
1534  Br.MaxDisp = ((1<<24)-1) * 2;
1535  MI->setDesc(TII->get(Mips::JalB16));
1536  }
1537  BBInfo[MBB->getNumber()].Size += 2;
1538  adjustBBOffsetsAfter(MBB);
1539  HasFarJump = true;
1540  ++NumUBrFixed;
1541 
1542  DEBUG(dbgs() << " Changed B to long jump " << *MI);
1543 
1544  return true;
1545 }
1546 
1547 /// fixupConditionalBr - Fix up a conditional branch whose destination is too
1548 /// far away to fit in its displacement field. It is converted to an inverse
1549 /// conditional branch + an unconditional branch to the destination.
1550 bool
1551 MipsConstantIslands::fixupConditionalBr(ImmBranch &Br) {
1552  MachineInstr *MI = Br.MI;
1553  unsigned TargetOperand = branchTargetOperand(MI);
1554  MachineBasicBlock *DestBB = MI->getOperand(TargetOperand).getMBB();
1555  unsigned Opcode = MI->getOpcode();
1556  unsigned LongFormOpcode = longformBranchOpcode(Opcode);
1557  unsigned LongFormMaxOff = branchMaxOffsets(LongFormOpcode);
1558 
1559  // Check to see if the DestBB is already in-range.
1560  if (isBBInRange(MI, DestBB, LongFormMaxOff)) {
1561  Br.MaxDisp = LongFormMaxOff;
1562  MI->setDesc(TII->get(LongFormOpcode));
1563  return true;
1564  }
1565 
1566  // Add an unconditional branch to the destination and invert the branch
1567  // condition to jump over it:
1568  // bteqz L1
1569  // =>
1570  // bnez L2
1571  // b L1
1572  // L2:
1573 
1574  // If the branch is at the end of its MBB and that has a fall-through block,
1575  // direct the updated conditional branch to the fall-through block. Otherwise,
1576  // split the MBB before the next instruction.
1577  MachineBasicBlock *MBB = MI->getParent();
1578  MachineInstr *BMI = &MBB->back();
1579  bool NeedSplit = (BMI != MI) || !BBHasFallthrough(MBB);
1580  unsigned OppositeBranchOpcode = TII->getOppositeBranchOpc(Opcode);
1581 
1582  ++NumCBrFixed;
1583  if (BMI != MI) {
1584  if (std::next(MachineBasicBlock::iterator(MI)) == std::prev(MBB->end()) &&
1585  BMI->isUnconditionalBranch()) {
1586  // Last MI in the BB is an unconditional branch. Can we simply invert the
1587  // condition and swap destinations:
1588  // beqz L1
1589  // b L2
1590  // =>
1591  // bnez L2
1592  // b L1
1593  unsigned BMITargetOperand = branchTargetOperand(BMI);
1594  MachineBasicBlock *NewDest =
1595  BMI->getOperand(BMITargetOperand).getMBB();
1596  if (isBBInRange(MI, NewDest, Br.MaxDisp)) {
1597  DEBUG(dbgs() << " Invert Bcc condition and swap its destination with "
1598  << *BMI);
1599  MI->setDesc(TII->get(OppositeBranchOpcode));
1600  BMI->getOperand(BMITargetOperand).setMBB(DestBB);
1601  MI->getOperand(TargetOperand).setMBB(NewDest);
1602  return true;
1603  }
1604  }
1605  }
1606 
1607  if (NeedSplit) {
1608  splitBlockBeforeInstr(*MI);
1609  // No need for the branch to the next block. We're adding an unconditional
1610  // branch to the destination.
1611  int delta = TII->getInstSizeInBytes(MBB->back());
1612  BBInfo[MBB->getNumber()].Size -= delta;
1613  MBB->back().eraseFromParent();
1614  // BBInfo[SplitBB].Offset is wrong temporarily, fixed below
1615  }
1616  MachineBasicBlock *NextBB = &*++MBB->getIterator();
1617 
1618  DEBUG(dbgs() << " Insert B to BB#" << DestBB->getNumber()
1619  << " also invert condition and change dest. to BB#"
1620  << NextBB->getNumber() << "\n");
1621 
1622  // Insert a new conditional branch and a new unconditional branch.
1623  // Also update the ImmBranch as well as adding a new entry for the new branch.
1624  if (MI->getNumExplicitOperands() == 2) {
1625  BuildMI(MBB, DebugLoc(), TII->get(OppositeBranchOpcode))
1626  .addReg(MI->getOperand(0).getReg())
1627  .addMBB(NextBB);
1628  } else {
1629  BuildMI(MBB, DebugLoc(), TII->get(OppositeBranchOpcode))
1630  .addMBB(NextBB);
1631  }
1632  Br.MI = &MBB->back();
1633  BBInfo[MBB->getNumber()].Size += TII->getInstSizeInBytes(MBB->back());
1634  BuildMI(MBB, DebugLoc(), TII->get(Br.UncondBr)).addMBB(DestBB);
1635  BBInfo[MBB->getNumber()].Size += TII->getInstSizeInBytes(MBB->back());
1636  unsigned MaxDisp = getUnconditionalBrDisp(Br.UncondBr);
1637  ImmBranches.push_back(ImmBranch(&MBB->back(), MaxDisp, false, Br.UncondBr));
1638 
1639  // Remove the old conditional branch. It may or may not still be in MBB.
1640  BBInfo[MI->getParent()->getNumber()].Size -= TII->getInstSizeInBytes(*MI);
1641  MI->eraseFromParent();
1642  adjustBBOffsetsAfter(MBB);
1643  return true;
1644 }
1645 
1646 void MipsConstantIslands::prescanForConstants() {
1647  unsigned J = 0;
1648  (void)J;
1650  MF->begin(), E = MF->end(); B != E; ++B) {
1652  B->instr_begin(), EB = B->instr_end(); I != EB; ++I) {
1653  switch(I->getDesc().getOpcode()) {
1654  case Mips::LwConstant32: {
1655  PrescannedForConstants = true;
1656  DEBUG(dbgs() << "constant island constant " << *I << "\n");
1657  J = I->getNumOperands();
1658  DEBUG(dbgs() << "num operands " << J << "\n");
1659  MachineOperand& Literal = I->getOperand(1);
1660  if (Literal.isImm()) {
1661  int64_t V = Literal.getImm();
1662  DEBUG(dbgs() << "literal " << V << "\n");
1663  Type *Int32Ty =
1664  Type::getInt32Ty(MF->getFunction()->getContext());
1665  const Constant *C = ConstantInt::get(Int32Ty, V);
1666  unsigned index = MCP->getConstantPoolIndex(C, 4);
1667  I->getOperand(2).ChangeToImmediate(index);
1668  DEBUG(dbgs() << "constant island constant " << *I << "\n");
1669  I->setDesc(TII->get(Mips::LwRxPcTcp16));
1670  I->RemoveOperand(1);
1671  I->RemoveOperand(1);
1672  I->addOperand(MachineOperand::CreateCPI(index, 0));
1673  I->addOperand(MachineOperand::CreateImm(4));
1674  }
1675  break;
1676  }
1677  default:
1678  break;
1679  }
1680  }
1681  }
1682 }
1683 
1684 /// Returns a pass that converts branches to long branches.
1686  return new MipsConstantIslands();
1687 }
uint64_t CallInst * C
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:109
constexpr char Align[]
Key for Kernel::Arg::Metadata::mAlign.
The MachineConstantPool class keeps track of constants referenced by a function which must be spilled...
static unsigned int branchTargetOperand(MachineInstr *MI)
static bool CompareMBBNumbers(const MachineBasicBlock *LHS, const MachineBasicBlock *RHS)
CompareMBBNumbers - Little predicate function to sort the WaterList by MBB ID.
MachineBasicBlock * getMBB() const
LLVM_ATTRIBUTE_NORETURN void report_fatal_error(Error Err, bool gen_crash_diag=true)
Report a serious error, calling any installed error handler.
Definition: Error.cpp:115
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
#define LLVM_DUMP_METHOD
Mark debug helper function definitions like dump() that should not be stripped from debug builds...
Definition: Compiler.h:449
void RenumberBlocks(MachineBasicBlock *MBBFrom=nullptr)
RenumberBlocks - This discards all of the MachineBasicBlock numbers and recomputes them...
LLVM_ATTRIBUTE_ALWAYS_INLINE size_type size() const
Definition: SmallVector.h:136
unsigned getReg() const
getReg - Returns the register number.
void transferSuccessors(MachineBasicBlock *FromMBB)
Transfers all the successors from MBB to this machine basic block (i.e., copies all the successors Fr...
format_object< Ts... > format(const char *Fmt, const Ts &... Vals)
These are helper functions used to produce formatted output.
Definition: Format.h:124
unsigned Offset
Offset - Distance from the beginning of the function to the beginning of this basic block...
static unsigned int branchMaxOffsets(unsigned int Opcode)
STATISTIC(NumFunctions, "Total number of functions")
A debug info location.
Definition: DebugLoc.h:34
F(f)
bool isCPI() const
isCPI - Tests if this is a MO_ConstantPoolIndex operand.
#define op(i)
bool isImm() const
isImm - Tests if this is a MO_Immediate operand.
void computeBlockSize(MachineFunction *MF, MachineBasicBlock *MBB, BasicBlockInfo &BBI)
void setAlignment(unsigned Align)
Set alignment of the basic block.
BasicBlockInfo - Information about the offset and size of a single basic block.
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
unsigned getNumOperands() const
Access to explicit operands of the instruction.
Definition: MachineInstr.h:293
void eraseFromParent()
Unlink &#39;this&#39; from the containing basic block and delete it.
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"))
unsigned getOpcode() const
Returns the opcode of this MachineInstr.
Definition: MachineInstr.h:290
MachineInstrBundleIterator< MachineInstr, true > reverse_iterator
auto lower_bound(R &&Range, ForwardIt I) -> decltype(adl_begin(Range))
Provide wrappers to std::lower_bound which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:904
int getNumber() const
MachineBasicBlocks are uniquely numbered at the function level, unless they&#39;re not in a MachineFuncti...
instr_iterator insert(instr_iterator I, MachineInstr *M)
Insert MI into the instruction list before I, possibly inside a bundle.
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)
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)
MachineInstrBuilder BuildMI(MachineFunction &MF, const DebugLoc &DL, const MCInstrDesc &MCID)
Builder interface. Specify how to create the initial instruction itself.
#define rc(i)
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:406
MachineInstrBundleIterator< MachineInstr > iterator
static unsigned int longformBranchOpcode(unsigned int Opcode)
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
constexpr bool isPowerOf2_32(uint32_t Value)
Return true if the argument is a power of two > 0.
Definition: MathExtras.h:421
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:46
const TargetSubtargetInfo & getSubtarget() const
getSubtarget - Return the subtarget for which this machine code is being compiled.
static bool BBIsJumpedOver(MachineBasicBlock *MBB)
BBIsJumpedOver - Return true of the specified basic block&#39;s only predecessor unconditionally branches...
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
This is an important base class in LLVM.
Definition: Constant.h:42
unsigned postOffset(unsigned LogAlign=0) const
Compute the offset immediately following this block.
SmallSet - This maintains a set of unique values, optimizing for the case when the set is small (less...
Definition: SmallSet.h:36
This file contains the declarations for the subclasses of Constant, which represent the different fla...
unsigned getAlignment() const
Return alignment of the basic block.
void setMBB(MachineBasicBlock *MBB)
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:285
FunctionPass * createMipsConstantIslandPass()
Returns a pass that converts branches to long branches.
self_iterator getIterator()
Definition: ilist_node.h:82
MachineConstantPool * getConstantPool()
getConstantPool - Return the constant pool object for the current function.
static wasm::ValType getType(const TargetRegisterClass *RC)
auto find(R &&Range, const T &Val) -> decltype(adl_begin(Range))
Provide wrappers to std::find which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:834
static unsigned getUnconditionalBrDisp(int Opc)
getUnconditionalBrDisp - Returns the maximum displacement that can fit in the specific unconditional ...
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
unsigned getNumExplicitOperands() const
Returns the number of non-implicit operands.
static bool useConstantIslands()
Iterator for intrusive lists based on ilist_node.
void addSuccessor(MachineBasicBlock *Succ, BranchProbability Prob=BranchProbability::getUnknown())
Add Succ as a successor of this MachineBasicBlock.
void setDesc(const MCInstrDesc &tid)
Replace the instruction descriptor (thus opcode) of the current instruction with a new one...
MachineOperand class - Representation of each machine instruction operand.
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:864
const MachineInstrBuilder & addConstantPoolIndex(unsigned Idx, int Offset=0, unsigned char TargetFlags=0) const
unsigned Size
Size - Size of the basic block in bytes.
APFloat neg(APFloat X)
Returns the negated value of the argument.
Definition: APFloat.h:1219
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:560
int64_t getImm() const
unsigned pred_size() const
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:132
unsigned Log2_32(uint32_t Value)
Return the floor log base 2 of the specified value, -1 if the value is zero.
Definition: MathExtras.h:531
bool isUnconditionalBranch(QueryType Type=AnyInBundle) const
Return true if this is a branch which always transfers control flow to some other block...
Definition: MachineInstr.h:504
unsigned succ_size() const
const MachineBasicBlock * getParent() const
Definition: MachineInstr.h:139
MachineFunctionProperties & set(Property P)
uint64_t getTypeAllocSize(Type *Ty) const
Returns the offset in bytes between successive objects of the specified type, including alignment pad...
Definition: DataLayout.h:403
Representation of each machine instruction.
Definition: MachineInstr.h:59
const MachineFunction * getParent() const
Return the MachineFunction containing this basic block.
const MachineInstrBuilder & addImm(int64_t Val) const
Add a new immediate operand.
void splice(iterator Where, MachineBasicBlock *Other, iterator From)
Take an instruction from MBB &#39;Other&#39; at the position From, and insert it into this MBB right before &#39;...
static IntegerType * getInt32Ty(LLVMContext &C)
Definition: Type.cpp:176
static bool BBHasFallthrough(MachineBasicBlock *MBB)
BBHasFallthrough - Return true if the specified basic block can fallthrough into the block immediatel...
static MachineOperand CreateImm(int64_t Val)
void push_back(MachineInstr *MI)
#define I(x, y, z)
Definition: MD5.cpp:58
const BasicBlock * getBasicBlock() const
Return the LLVM basic block that this instance corresponded to originally.
MipsFunctionInfo - This class is derived from MachineFunction private Mips target-specific informatio...
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
constexpr char Size[]
Key for Kernel::Arg::Metadata::mSize.
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:719
#define DEBUG(X)
Definition: Debug.h:118
IRTranslator LLVM IR MI
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49
const MachineOperand & getOperand(unsigned i) const
Definition: MachineInstr.h:295
std::vector< MachineBasicBlock * >::iterator succ_iterator
Properties which a MachineFunction may have at a given point in time.
IntegerType * Int32Ty