LLVM  9.0.0svn
MipsConstantIslandPass.cpp
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1 //===- MipsConstantIslandPass.cpp - Emit Pc Relative loads ----------------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This pass is used to make Pc relative loads of constants.
10 // For now, only Mips16 will use this.
11 //
12 // Loading constants inline is expensive on Mips16 and it's in general better
13 // to place the constant nearby in code space and then it can be loaded with a
14 // simple 16 bit load instruction.
15 //
16 // The constants can be not just numbers but addresses of functions and labels.
17 // This can be particularly helpful in static relocation mode for embedded
18 // non-linux targets.
19 //
20 //===----------------------------------------------------------------------===//
21 
22 #include "Mips.h"
23 #include "Mips16InstrInfo.h"
24 #include "MipsMachineFunction.h"
25 #include "MipsSubtarget.h"
26 #include "llvm/ADT/STLExtras.h"
27 #include "llvm/ADT/SmallSet.h"
28 #include "llvm/ADT/SmallVector.h"
29 #include "llvm/ADT/Statistic.h"
30 #include "llvm/ADT/StringRef.h"
39 #include "llvm/Config/llvm-config.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  LLVM_DEBUG(dbgs() << "constant island machine function "
446  << "\n");
447  if (!STI->inMips16Mode() || !MipsSubtarget::useConstantIslands()) {
448  return false;
449  }
450  TII = (const Mips16InstrInfo *)STI->getInstrInfo();
451  MFI = MF->getInfo<MipsFunctionInfo>();
452  LLVM_DEBUG(dbgs() << "constant island processing "
453  << "\n");
454  //
455  // will need to make predermination if there is any constants we need to
456  // put in constant islands. TBD.
457  //
458  if (!PrescannedForConstants) prescanForConstants();
459 
460  HasFarJump = false;
461  // This pass invalidates liveness information when it splits basic blocks.
462  MF->getRegInfo().invalidateLiveness();
463 
464  // Renumber all of the machine basic blocks in the function, guaranteeing that
465  // the numbers agree with the position of the block in the function.
466  MF->RenumberBlocks();
467 
468  bool MadeChange = false;
469 
470  // Perform the initial placement of the constant pool entries. To start with,
471  // we put them all at the end of the function.
472  std::vector<MachineInstr*> CPEMIs;
473  if (!MCP->isEmpty())
474  doInitialPlacement(CPEMIs);
475 
476  /// The next UID to take is the first unused one.
477  initPICLabelUId(CPEMIs.size());
478 
479  // Do the initial scan of the function, building up information about the
480  // sizes of each block, the location of all the water, and finding all of the
481  // constant pool users.
482  initializeFunctionInfo(CPEMIs);
483  CPEMIs.clear();
484  LLVM_DEBUG(dumpBBs());
485 
486  /// Remove dead constant pool entries.
487  MadeChange |= removeUnusedCPEntries();
488 
489  // Iteratively place constant pool entries and fix up branches until there
490  // is no change.
491  unsigned NoCPIters = 0, NoBRIters = 0;
492  (void)NoBRIters;
493  while (true) {
494  LLVM_DEBUG(dbgs() << "Beginning CP iteration #" << NoCPIters << '\n');
495  bool CPChange = false;
496  for (unsigned i = 0, e = CPUsers.size(); i != e; ++i)
497  CPChange |= handleConstantPoolUser(i);
498  if (CPChange && ++NoCPIters > 30)
499  report_fatal_error("Constant Island pass failed to converge!");
500  LLVM_DEBUG(dumpBBs());
501 
502  // Clear NewWaterList now. If we split a block for branches, it should
503  // appear as "new water" for the next iteration of constant pool placement.
504  NewWaterList.clear();
505 
506  LLVM_DEBUG(dbgs() << "Beginning BR iteration #" << NoBRIters << '\n');
507  bool BRChange = false;
508  for (unsigned i = 0, e = ImmBranches.size(); i != e; ++i)
509  BRChange |= fixupImmediateBr(ImmBranches[i]);
510  if (BRChange && ++NoBRIters > 30)
511  report_fatal_error("Branch Fix Up pass failed to converge!");
512  LLVM_DEBUG(dumpBBs());
513  if (!CPChange && !BRChange)
514  break;
515  MadeChange = true;
516  }
517 
518  LLVM_DEBUG(dbgs() << '\n'; dumpBBs());
519 
520  BBInfo.clear();
521  WaterList.clear();
522  CPUsers.clear();
523  CPEntries.clear();
524  ImmBranches.clear();
525  return MadeChange;
526 }
527 
528 /// doInitialPlacement - Perform the initial placement of the constant pool
529 /// entries. To start with, we put them all at the end of the function.
530 void
531 MipsConstantIslands::doInitialPlacement(std::vector<MachineInstr*> &CPEMIs) {
532  // Create the basic block to hold the CPE's.
533  MachineBasicBlock *BB = MF->CreateMachineBasicBlock();
534  MF->push_back(BB);
535 
536  // MachineConstantPool measures alignment in bytes. We measure in log2(bytes).
537  unsigned MaxAlign = Log2_32(MCP->getConstantPoolAlignment());
538 
539  // Mark the basic block as required by the const-pool.
540  // If AlignConstantIslands isn't set, use 4-byte alignment for everything.
541  BB->setAlignment(AlignConstantIslands ? MaxAlign : 2);
542 
543  // The function needs to be as aligned as the basic blocks. The linker may
544  // move functions around based on their alignment.
545  MF->ensureAlignment(BB->getAlignment());
546 
547  // Order the entries in BB by descending alignment. That ensures correct
548  // alignment of all entries as long as BB is sufficiently aligned. Keep
549  // track of the insertion point for each alignment. We are going to bucket
550  // sort the entries as they are created.
551  SmallVector<MachineBasicBlock::iterator, 8> InsPoint(MaxAlign + 1, BB->end());
552 
553  // Add all of the constants from the constant pool to the end block, use an
554  // identity mapping of CPI's to CPE's.
555  const std::vector<MachineConstantPoolEntry> &CPs = MCP->getConstants();
556 
557  const DataLayout &TD = MF->getDataLayout();
558  for (unsigned i = 0, e = CPs.size(); i != e; ++i) {
559  unsigned Size = TD.getTypeAllocSize(CPs[i].getType());
560  assert(Size >= 4 && "Too small constant pool entry");
561  unsigned Align = CPs[i].getAlignment();
562  assert(isPowerOf2_32(Align) && "Invalid alignment");
563  // Verify that all constant pool entries are a multiple of their alignment.
564  // If not, we would have to pad them out so that instructions stay aligned.
565  assert((Size % Align) == 0 && "CP Entry not multiple of 4 bytes!");
566 
567  // Insert CONSTPOOL_ENTRY before entries with a smaller alignment.
568  unsigned LogAlign = Log2_32(Align);
569  MachineBasicBlock::iterator InsAt = InsPoint[LogAlign];
570 
571  MachineInstr *CPEMI =
572  BuildMI(*BB, InsAt, DebugLoc(), TII->get(Mips::CONSTPOOL_ENTRY))
573  .addImm(i).addConstantPoolIndex(i).addImm(Size);
574 
575  CPEMIs.push_back(CPEMI);
576 
577  // Ensure that future entries with higher alignment get inserted before
578  // CPEMI. This is bucket sort with iterators.
579  for (unsigned a = LogAlign + 1; a <= MaxAlign; ++a)
580  if (InsPoint[a] == InsAt)
581  InsPoint[a] = CPEMI;
582  // Add a new CPEntry, but no corresponding CPUser yet.
583  CPEntries.emplace_back(1, CPEntry(CPEMI, i));
584  ++NumCPEs;
585  LLVM_DEBUG(dbgs() << "Moved CPI#" << i << " to end of function, size = "
586  << Size << ", align = " << Align << '\n');
587  }
588  LLVM_DEBUG(BB->dump());
589 }
590 
591 /// BBHasFallthrough - Return true if the specified basic block can fallthrough
592 /// into the block immediately after it.
594  // Get the next machine basic block in the function.
596  // Can't fall off end of function.
597  if (std::next(MBBI) == MBB->getParent()->end())
598  return false;
599 
600  MachineBasicBlock *NextBB = &*std::next(MBBI);
602  E = MBB->succ_end(); I != E; ++I)
603  if (*I == NextBB)
604  return true;
605 
606  return false;
607 }
608 
609 /// findConstPoolEntry - Given the constpool index and CONSTPOOL_ENTRY MI,
610 /// look up the corresponding CPEntry.
611 MipsConstantIslands::CPEntry
612 *MipsConstantIslands::findConstPoolEntry(unsigned CPI,
613  const MachineInstr *CPEMI) {
614  std::vector<CPEntry> &CPEs = CPEntries[CPI];
615  // Number of entries per constpool index should be small, just do a
616  // linear search.
617  for (unsigned i = 0, e = CPEs.size(); i != e; ++i) {
618  if (CPEs[i].CPEMI == CPEMI)
619  return &CPEs[i];
620  }
621  return nullptr;
622 }
623 
624 /// getCPELogAlign - Returns the required alignment of the constant pool entry
625 /// represented by CPEMI. Alignment is measured in log2(bytes) units.
626 unsigned MipsConstantIslands::getCPELogAlign(const MachineInstr &CPEMI) {
627  assert(CPEMI.getOpcode() == Mips::CONSTPOOL_ENTRY);
628 
629  // Everything is 4-byte aligned unless AlignConstantIslands is set.
631  return 2;
632 
633  unsigned CPI = CPEMI.getOperand(1).getIndex();
634  assert(CPI < MCP->getConstants().size() && "Invalid constant pool index.");
635  unsigned Align = MCP->getConstants()[CPI].getAlignment();
636  assert(isPowerOf2_32(Align) && "Invalid CPE alignment");
637  return Log2_32(Align);
638 }
639 
640 /// initializeFunctionInfo - Do the initial scan of the function, building up
641 /// information about the sizes of each block, the location of all the water,
642 /// and finding all of the constant pool users.
643 void MipsConstantIslands::
644 initializeFunctionInfo(const std::vector<MachineInstr*> &CPEMIs) {
645  BBInfo.clear();
646  BBInfo.resize(MF->getNumBlockIDs());
647 
648  // First thing, compute the size of all basic blocks, and see if the function
649  // has any inline assembly in it. If so, we have to be conservative about
650  // alignment assumptions, as we don't know for sure the size of any
651  // instructions in the inline assembly.
652  for (MachineFunction::iterator I = MF->begin(), E = MF->end(); I != E; ++I)
653  computeBlockSize(&*I);
654 
655  // Compute block offsets.
656  adjustBBOffsetsAfter(&MF->front());
657 
658  // Now go back through the instructions and build up our data structures.
659  for (MachineBasicBlock &MBB : *MF) {
660  // If this block doesn't fall through into the next MBB, then this is
661  // 'water' that a constant pool island could be placed.
662  if (!BBHasFallthrough(&MBB))
663  WaterList.push_back(&MBB);
664  for (MachineInstr &MI : MBB) {
665  if (MI.isDebugInstr())
666  continue;
667 
668  int Opc = MI.getOpcode();
669  if (MI.isBranch()) {
670  bool isCond = false;
671  unsigned Bits = 0;
672  unsigned Scale = 1;
673  int UOpc = Opc;
674  switch (Opc) {
675  default:
676  continue; // Ignore other branches for now
677  case Mips::Bimm16:
678  Bits = 11;
679  Scale = 2;
680  isCond = false;
681  break;
682  case Mips::BimmX16:
683  Bits = 16;
684  Scale = 2;
685  isCond = false;
686  break;
687  case Mips::BeqzRxImm16:
688  UOpc=Mips::Bimm16;
689  Bits = 8;
690  Scale = 2;
691  isCond = true;
692  break;
693  case Mips::BeqzRxImmX16:
694  UOpc=Mips::Bimm16;
695  Bits = 16;
696  Scale = 2;
697  isCond = true;
698  break;
699  case Mips::BnezRxImm16:
700  UOpc=Mips::Bimm16;
701  Bits = 8;
702  Scale = 2;
703  isCond = true;
704  break;
705  case Mips::BnezRxImmX16:
706  UOpc=Mips::Bimm16;
707  Bits = 16;
708  Scale = 2;
709  isCond = true;
710  break;
711  case Mips::Bteqz16:
712  UOpc=Mips::Bimm16;
713  Bits = 8;
714  Scale = 2;
715  isCond = true;
716  break;
717  case Mips::BteqzX16:
718  UOpc=Mips::Bimm16;
719  Bits = 16;
720  Scale = 2;
721  isCond = true;
722  break;
723  case Mips::Btnez16:
724  UOpc=Mips::Bimm16;
725  Bits = 8;
726  Scale = 2;
727  isCond = true;
728  break;
729  case Mips::BtnezX16:
730  UOpc=Mips::Bimm16;
731  Bits = 16;
732  Scale = 2;
733  isCond = true;
734  break;
735  }
736  // Record this immediate branch.
737  unsigned MaxOffs = ((1 << (Bits-1))-1) * Scale;
738  ImmBranches.push_back(ImmBranch(&MI, MaxOffs, isCond, UOpc));
739  }
740 
741  if (Opc == Mips::CONSTPOOL_ENTRY)
742  continue;
743 
744  // Scan the instructions for constant pool operands.
745  for (unsigned op = 0, e = MI.getNumOperands(); op != e; ++op)
746  if (MI.getOperand(op).isCPI()) {
747  // We found one. The addressing mode tells us the max displacement
748  // from the PC that this instruction permits.
749 
750  // Basic size info comes from the TSFlags field.
751  unsigned Bits = 0;
752  unsigned Scale = 1;
753  bool NegOk = false;
754  unsigned LongFormBits = 0;
755  unsigned LongFormScale = 0;
756  unsigned LongFormOpcode = 0;
757  switch (Opc) {
758  default:
759  llvm_unreachable("Unknown addressing mode for CP reference!");
760  case Mips::LwRxPcTcp16:
761  Bits = 8;
762  Scale = 4;
763  LongFormOpcode = Mips::LwRxPcTcpX16;
764  LongFormBits = 14;
765  LongFormScale = 1;
766  break;
767  case Mips::LwRxPcTcpX16:
768  Bits = 14;
769  Scale = 1;
770  NegOk = true;
771  break;
772  }
773  // Remember that this is a user of a CP entry.
774  unsigned CPI = MI.getOperand(op).getIndex();
775  MachineInstr *CPEMI = CPEMIs[CPI];
776  unsigned MaxOffs = ((1 << Bits)-1) * Scale;
777  unsigned LongFormMaxOffs = ((1 << LongFormBits)-1) * LongFormScale;
778  CPUsers.push_back(CPUser(&MI, CPEMI, MaxOffs, NegOk, LongFormMaxOffs,
779  LongFormOpcode));
780 
781  // Increment corresponding CPEntry reference count.
782  CPEntry *CPE = findConstPoolEntry(CPI, CPEMI);
783  assert(CPE && "Cannot find a corresponding CPEntry!");
784  CPE->RefCount++;
785 
786  // Instructions can only use one CP entry, don't bother scanning the
787  // rest of the operands.
788  break;
789  }
790  }
791  }
792 }
793 
794 /// computeBlockSize - Compute the size and some alignment information for MBB.
795 /// This function updates BBInfo directly.
797  BasicBlockInfo &BBI = BBInfo[MBB->getNumber()];
798  BBI.Size = 0;
799 
800  for (const MachineInstr &MI : *MBB)
801  BBI.Size += TII->getInstSizeInBytes(MI);
802 }
803 
804 /// getOffsetOf - Return the current offset of the specified machine instruction
805 /// from the start of the function. This offset changes as stuff is moved
806 /// around inside the function.
807 unsigned MipsConstantIslands::getOffsetOf(MachineInstr *MI) const {
808  MachineBasicBlock *MBB = MI->getParent();
809 
810  // The offset is composed of two things: the sum of the sizes of all MBB's
811  // before this instruction's block, and the offset from the start of the block
812  // it is in.
813  unsigned Offset = BBInfo[MBB->getNumber()].Offset;
814 
815  // Sum instructions before MI in MBB.
816  for (MachineBasicBlock::iterator I = MBB->begin(); &*I != MI; ++I) {
817  assert(I != MBB->end() && "Didn't find MI in its own basic block?");
818  Offset += TII->getInstSizeInBytes(*I);
819  }
820  return Offset;
821 }
822 
823 /// CompareMBBNumbers - Little predicate function to sort the WaterList by MBB
824 /// ID.
825 static bool CompareMBBNumbers(const MachineBasicBlock *LHS,
826  const MachineBasicBlock *RHS) {
827  return LHS->getNumber() < RHS->getNumber();
828 }
829 
830 /// updateForInsertedWaterBlock - When a block is newly inserted into the
831 /// machine function, it upsets all of the block numbers. Renumber the blocks
832 /// and update the arrays that parallel this numbering.
833 void MipsConstantIslands::updateForInsertedWaterBlock
834  (MachineBasicBlock *NewBB) {
835  // Renumber the MBB's to keep them consecutive.
836  NewBB->getParent()->RenumberBlocks(NewBB);
837 
838  // Insert an entry into BBInfo to align it properly with the (newly
839  // renumbered) block numbers.
840  BBInfo.insert(BBInfo.begin() + NewBB->getNumber(), BasicBlockInfo());
841 
842  // Next, update WaterList. Specifically, we need to add NewMBB as having
843  // available water after it.
844  water_iterator IP =
845  std::lower_bound(WaterList.begin(), WaterList.end(), NewBB,
847  WaterList.insert(IP, NewBB);
848 }
849 
850 unsigned MipsConstantIslands::getUserOffset(CPUser &U) const {
851  return getOffsetOf(U.MI);
852 }
853 
854 /// Split the basic block containing MI into two blocks, which are joined by
855 /// an unconditional branch. Update data structures and renumber blocks to
856 /// account for this change and returns the newly created block.
858 MipsConstantIslands::splitBlockBeforeInstr(MachineInstr &MI) {
859  MachineBasicBlock *OrigBB = MI.getParent();
860 
861  // Create a new MBB for the code after the OrigBB.
862  MachineBasicBlock *NewBB =
863  MF->CreateMachineBasicBlock(OrigBB->getBasicBlock());
864  MachineFunction::iterator MBBI = ++OrigBB->getIterator();
865  MF->insert(MBBI, NewBB);
866 
867  // Splice the instructions starting with MI over to NewBB.
868  NewBB->splice(NewBB->end(), OrigBB, MI, OrigBB->end());
869 
870  // Add an unconditional branch from OrigBB to NewBB.
871  // Note the new unconditional branch is not being recorded.
872  // There doesn't seem to be meaningful DebugInfo available; this doesn't
873  // correspond to anything in the source.
874  BuildMI(OrigBB, DebugLoc(), TII->get(Mips::Bimm16)).addMBB(NewBB);
875  ++NumSplit;
876 
877  // Update the CFG. All succs of OrigBB are now succs of NewBB.
878  NewBB->transferSuccessors(OrigBB);
879 
880  // OrigBB branches to NewBB.
881  OrigBB->addSuccessor(NewBB);
882 
883  // Update internal data structures to account for the newly inserted MBB.
884  // This is almost the same as updateForInsertedWaterBlock, except that
885  // the Water goes after OrigBB, not NewBB.
886  MF->RenumberBlocks(NewBB);
887 
888  // Insert an entry into BBInfo to align it properly with the (newly
889  // renumbered) block numbers.
890  BBInfo.insert(BBInfo.begin() + NewBB->getNumber(), BasicBlockInfo());
891 
892  // Next, update WaterList. Specifically, we need to add OrigMBB as having
893  // available water after it (but not if it's already there, which happens
894  // when splitting before a conditional branch that is followed by an
895  // unconditional branch - in that case we want to insert NewBB).
896  water_iterator IP =
897  std::lower_bound(WaterList.begin(), WaterList.end(), OrigBB,
899  MachineBasicBlock* WaterBB = *IP;
900  if (WaterBB == OrigBB)
901  WaterList.insert(std::next(IP), NewBB);
902  else
903  WaterList.insert(IP, OrigBB);
904  NewWaterList.insert(OrigBB);
905 
906  // Figure out how large the OrigBB is. As the first half of the original
907  // block, it cannot contain a tablejump. The size includes
908  // the new jump we added. (It should be possible to do this without
909  // recounting everything, but it's very confusing, and this is rarely
910  // executed.)
911  computeBlockSize(OrigBB);
912 
913  // Figure out how large the NewMBB is. As the second half of the original
914  // block, it may contain a tablejump.
915  computeBlockSize(NewBB);
916 
917  // All BBOffsets following these blocks must be modified.
918  adjustBBOffsetsAfter(OrigBB);
919 
920  return NewBB;
921 }
922 
923 /// isOffsetInRange - Checks whether UserOffset (the location of a constant pool
924 /// reference) is within MaxDisp of TrialOffset (a proposed location of a
925 /// constant pool entry).
926 bool MipsConstantIslands::isOffsetInRange(unsigned UserOffset,
927  unsigned TrialOffset, unsigned MaxDisp,
928  bool NegativeOK) {
929  if (UserOffset <= TrialOffset) {
930  // User before the Trial.
931  if (TrialOffset - UserOffset <= MaxDisp)
932  return true;
933  } else if (NegativeOK) {
934  if (UserOffset - TrialOffset <= MaxDisp)
935  return true;
936  }
937  return false;
938 }
939 
940 /// isWaterInRange - Returns true if a CPE placed after the specified
941 /// Water (a basic block) will be in range for the specific MI.
942 ///
943 /// Compute how much the function will grow by inserting a CPE after Water.
944 bool MipsConstantIslands::isWaterInRange(unsigned UserOffset,
945  MachineBasicBlock* Water, CPUser &U,
946  unsigned &Growth) {
947  unsigned CPELogAlign = getCPELogAlign(*U.CPEMI);
948  unsigned CPEOffset = BBInfo[Water->getNumber()].postOffset(CPELogAlign);
949  unsigned NextBlockOffset, NextBlockAlignment;
950  MachineFunction::const_iterator NextBlock = ++Water->getIterator();
951  if (NextBlock == MF->end()) {
952  NextBlockOffset = BBInfo[Water->getNumber()].postOffset();
953  NextBlockAlignment = 0;
954  } else {
955  NextBlockOffset = BBInfo[NextBlock->getNumber()].Offset;
956  NextBlockAlignment = NextBlock->getAlignment();
957  }
958  unsigned Size = U.CPEMI->getOperand(2).getImm();
959  unsigned CPEEnd = CPEOffset + Size;
960 
961  // The CPE may be able to hide in the alignment padding before the next
962  // block. It may also cause more padding to be required if it is more aligned
963  // that the next block.
964  if (CPEEnd > NextBlockOffset) {
965  Growth = CPEEnd - NextBlockOffset;
966  // Compute the padding that would go at the end of the CPE to align the next
967  // block.
968  Growth += OffsetToAlignment(CPEEnd, 1ULL << NextBlockAlignment);
969 
970  // If the CPE is to be inserted before the instruction, that will raise
971  // the offset of the instruction. Also account for unknown alignment padding
972  // in blocks between CPE and the user.
973  if (CPEOffset < UserOffset)
974  UserOffset += Growth;
975  } else
976  // CPE fits in existing padding.
977  Growth = 0;
978 
979  return isOffsetInRange(UserOffset, CPEOffset, U);
980 }
981 
982 /// isCPEntryInRange - Returns true if the distance between specific MI and
983 /// specific ConstPool entry instruction can fit in MI's displacement field.
984 bool MipsConstantIslands::isCPEntryInRange
985  (MachineInstr *MI, unsigned UserOffset,
986  MachineInstr *CPEMI, unsigned MaxDisp,
987  bool NegOk, bool DoDump) {
988  unsigned CPEOffset = getOffsetOf(CPEMI);
989 
990  if (DoDump) {
991  LLVM_DEBUG({
992  unsigned Block = MI->getParent()->getNumber();
993  const BasicBlockInfo &BBI = BBInfo[Block];
994  dbgs() << "User of CPE#" << CPEMI->getOperand(0).getImm()
995  << " max delta=" << MaxDisp
996  << format(" insn address=%#x", UserOffset) << " in "
997  << printMBBReference(*MI->getParent()) << ": "
998  << format("%#x-%x\t", BBI.Offset, BBI.postOffset()) << *MI
999  << format("CPE address=%#x offset=%+d: ", CPEOffset,
1000  int(CPEOffset - UserOffset));
1001  });
1002  }
1003 
1004  return isOffsetInRange(UserOffset, CPEOffset, MaxDisp, NegOk);
1005 }
1006 
1007 #ifndef NDEBUG
1008 /// BBIsJumpedOver - Return true of the specified basic block's only predecessor
1009 /// unconditionally branches to its only successor.
1011  if (MBB->pred_size() != 1 || MBB->succ_size() != 1)
1012  return false;
1013  MachineBasicBlock *Succ = *MBB->succ_begin();
1014  MachineBasicBlock *Pred = *MBB->pred_begin();
1015  MachineInstr *PredMI = &Pred->back();
1016  if (PredMI->getOpcode() == Mips::Bimm16)
1017  return PredMI->getOperand(0).getMBB() == Succ;
1018  return false;
1019 }
1020 #endif
1021 
1022 void MipsConstantIslands::adjustBBOffsetsAfter(MachineBasicBlock *BB) {
1023  unsigned BBNum = BB->getNumber();
1024  for(unsigned i = BBNum + 1, e = MF->getNumBlockIDs(); i < e; ++i) {
1025  // Get the offset and known bits at the end of the layout predecessor.
1026  // Include the alignment of the current block.
1027  unsigned Offset = BBInfo[i - 1].Offset + BBInfo[i - 1].Size;
1028  BBInfo[i].Offset = Offset;
1029  }
1030 }
1031 
1032 /// decrementCPEReferenceCount - find the constant pool entry with index CPI
1033 /// and instruction CPEMI, and decrement its refcount. If the refcount
1034 /// becomes 0 remove the entry and instruction. Returns true if we removed
1035 /// the entry, false if we didn't.
1036 bool MipsConstantIslands::decrementCPEReferenceCount(unsigned CPI,
1037  MachineInstr *CPEMI) {
1038  // Find the old entry. Eliminate it if it is no longer used.
1039  CPEntry *CPE = findConstPoolEntry(CPI, CPEMI);
1040  assert(CPE && "Unexpected!");
1041  if (--CPE->RefCount == 0) {
1042  removeDeadCPEMI(CPEMI);
1043  CPE->CPEMI = nullptr;
1044  --NumCPEs;
1045  return true;
1046  }
1047  return false;
1048 }
1049 
1050 /// LookForCPEntryInRange - see if the currently referenced CPE is in range;
1051 /// if not, see if an in-range clone of the CPE is in range, and if so,
1052 /// change the data structures so the user references the clone. Returns:
1053 /// 0 = no existing entry found
1054 /// 1 = entry found, and there were no code insertions or deletions
1055 /// 2 = entry found, and there were code insertions or deletions
1056 int MipsConstantIslands::findInRangeCPEntry(CPUser& U, unsigned UserOffset)
1057 {
1058  MachineInstr *UserMI = U.MI;
1059  MachineInstr *CPEMI = U.CPEMI;
1060 
1061  // Check to see if the CPE is already in-range.
1062  if (isCPEntryInRange(UserMI, UserOffset, CPEMI, U.getMaxDisp(), U.NegOk,
1063  true)) {
1064  LLVM_DEBUG(dbgs() << "In range\n");
1065  return 1;
1066  }
1067 
1068  // No. Look for previously created clones of the CPE that are in range.
1069  unsigned CPI = CPEMI->getOperand(1).getIndex();
1070  std::vector<CPEntry> &CPEs = CPEntries[CPI];
1071  for (unsigned i = 0, e = CPEs.size(); i != e; ++i) {
1072  // We already tried this one
1073  if (CPEs[i].CPEMI == CPEMI)
1074  continue;
1075  // Removing CPEs can leave empty entries, skip
1076  if (CPEs[i].CPEMI == nullptr)
1077  continue;
1078  if (isCPEntryInRange(UserMI, UserOffset, CPEs[i].CPEMI, U.getMaxDisp(),
1079  U.NegOk)) {
1080  LLVM_DEBUG(dbgs() << "Replacing CPE#" << CPI << " with CPE#"
1081  << CPEs[i].CPI << "\n");
1082  // Point the CPUser node to the replacement
1083  U.CPEMI = CPEs[i].CPEMI;
1084  // Change the CPI in the instruction operand to refer to the clone.
1085  for (unsigned j = 0, e = UserMI->getNumOperands(); j != e; ++j)
1086  if (UserMI->getOperand(j).isCPI()) {
1087  UserMI->getOperand(j).setIndex(CPEs[i].CPI);
1088  break;
1089  }
1090  // Adjust the refcount of the clone...
1091  CPEs[i].RefCount++;
1092  // ...and the original. If we didn't remove the old entry, none of the
1093  // addresses changed, so we don't need another pass.
1094  return decrementCPEReferenceCount(CPI, CPEMI) ? 2 : 1;
1095  }
1096  }
1097  return 0;
1098 }
1099 
1100 /// LookForCPEntryInRange - see if the currently referenced CPE is in range;
1101 /// This version checks if the longer form of the instruction can be used to
1102 /// to satisfy things.
1103 /// if not, see if an in-range clone of the CPE is in range, and if so,
1104 /// change the data structures so the user references the clone. Returns:
1105 /// 0 = no existing entry found
1106 /// 1 = entry found, and there were no code insertions or deletions
1107 /// 2 = entry found, and there were code insertions or deletions
1108 int MipsConstantIslands::findLongFormInRangeCPEntry
1109  (CPUser& U, unsigned UserOffset)
1110 {
1111  MachineInstr *UserMI = U.MI;
1112  MachineInstr *CPEMI = U.CPEMI;
1113 
1114  // Check to see if the CPE is already in-range.
1115  if (isCPEntryInRange(UserMI, UserOffset, CPEMI,
1116  U.getLongFormMaxDisp(), U.NegOk,
1117  true)) {
1118  LLVM_DEBUG(dbgs() << "In range\n");
1119  UserMI->setDesc(TII->get(U.getLongFormOpcode()));
1120  U.setMaxDisp(U.getLongFormMaxDisp());
1121  return 2; // instruction is longer length now
1122  }
1123 
1124  // No. Look for previously created clones of the CPE that are in range.
1125  unsigned CPI = CPEMI->getOperand(1).getIndex();
1126  std::vector<CPEntry> &CPEs = CPEntries[CPI];
1127  for (unsigned i = 0, e = CPEs.size(); i != e; ++i) {
1128  // We already tried this one
1129  if (CPEs[i].CPEMI == CPEMI)
1130  continue;
1131  // Removing CPEs can leave empty entries, skip
1132  if (CPEs[i].CPEMI == nullptr)
1133  continue;
1134  if (isCPEntryInRange(UserMI, UserOffset, CPEs[i].CPEMI,
1135  U.getLongFormMaxDisp(), U.NegOk)) {
1136  LLVM_DEBUG(dbgs() << "Replacing CPE#" << CPI << " with CPE#"
1137  << CPEs[i].CPI << "\n");
1138  // Point the CPUser node to the replacement
1139  U.CPEMI = CPEs[i].CPEMI;
1140  // Change the CPI in the instruction operand to refer to the clone.
1141  for (unsigned j = 0, e = UserMI->getNumOperands(); j != e; ++j)
1142  if (UserMI->getOperand(j).isCPI()) {
1143  UserMI->getOperand(j).setIndex(CPEs[i].CPI);
1144  break;
1145  }
1146  // Adjust the refcount of the clone...
1147  CPEs[i].RefCount++;
1148  // ...and the original. If we didn't remove the old entry, none of the
1149  // addresses changed, so we don't need another pass.
1150  return decrementCPEReferenceCount(CPI, CPEMI) ? 2 : 1;
1151  }
1152  }
1153  return 0;
1154 }
1155 
1156 /// getUnconditionalBrDisp - Returns the maximum displacement that can fit in
1157 /// the specific unconditional branch instruction.
1158 static inline unsigned getUnconditionalBrDisp(int Opc) {
1159  switch (Opc) {
1160  case Mips::Bimm16:
1161  return ((1<<10)-1)*2;
1162  case Mips::BimmX16:
1163  return ((1<<16)-1)*2;
1164  default:
1165  break;
1166  }
1167  return ((1<<16)-1)*2;
1168 }
1169 
1170 /// findAvailableWater - Look for an existing entry in the WaterList in which
1171 /// we can place the CPE referenced from U so it's within range of U's MI.
1172 /// Returns true if found, false if not. If it returns true, WaterIter
1173 /// is set to the WaterList entry.
1174 /// To ensure that this pass
1175 /// terminates, the CPE location for a particular CPUser is only allowed to
1176 /// move to a lower address, so search backward from the end of the list and
1177 /// prefer the first water that is in range.
1178 bool MipsConstantIslands::findAvailableWater(CPUser &U, unsigned UserOffset,
1179  water_iterator &WaterIter) {
1180  if (WaterList.empty())
1181  return false;
1182 
1183  unsigned BestGrowth = ~0u;
1184  for (water_iterator IP = std::prev(WaterList.end()), B = WaterList.begin();;
1185  --IP) {
1186  MachineBasicBlock* WaterBB = *IP;
1187  // Check if water is in range and is either at a lower address than the
1188  // current "high water mark" or a new water block that was created since
1189  // the previous iteration by inserting an unconditional branch. In the
1190  // latter case, we want to allow resetting the high water mark back to
1191  // this new water since we haven't seen it before. Inserting branches
1192  // should be relatively uncommon and when it does happen, we want to be
1193  // sure to take advantage of it for all the CPEs near that block, so that
1194  // we don't insert more branches than necessary.
1195  unsigned Growth;
1196  if (isWaterInRange(UserOffset, WaterBB, U, Growth) &&
1197  (WaterBB->getNumber() < U.HighWaterMark->getNumber() ||
1198  NewWaterList.count(WaterBB)) && Growth < BestGrowth) {
1199  // This is the least amount of required padding seen so far.
1200  BestGrowth = Growth;
1201  WaterIter = IP;
1202  LLVM_DEBUG(dbgs() << "Found water after " << printMBBReference(*WaterBB)
1203  << " Growth=" << Growth << '\n');
1204 
1205  // Keep looking unless it is perfect.
1206  if (BestGrowth == 0)
1207  return true;
1208  }
1209  if (IP == B)
1210  break;
1211  }
1212  return BestGrowth != ~0u;
1213 }
1214 
1215 /// createNewWater - No existing WaterList entry will work for
1216 /// CPUsers[CPUserIndex], so create a place to put the CPE. The end of the
1217 /// block is used if in range, and the conditional branch munged so control
1218 /// flow is correct. Otherwise the block is split to create a hole with an
1219 /// unconditional branch around it. In either case NewMBB is set to a
1220 /// block following which the new island can be inserted (the WaterList
1221 /// is not adjusted).
1222 void MipsConstantIslands::createNewWater(unsigned CPUserIndex,
1223  unsigned UserOffset,
1224  MachineBasicBlock *&NewMBB) {
1225  CPUser &U = CPUsers[CPUserIndex];
1226  MachineInstr *UserMI = U.MI;
1227  MachineInstr *CPEMI = U.CPEMI;
1228  unsigned CPELogAlign = getCPELogAlign(*CPEMI);
1229  MachineBasicBlock *UserMBB = UserMI->getParent();
1230  const BasicBlockInfo &UserBBI = BBInfo[UserMBB->getNumber()];
1231 
1232  // If the block does not end in an unconditional branch already, and if the
1233  // end of the block is within range, make new water there.
1234  if (BBHasFallthrough(UserMBB)) {
1235  // Size of branch to insert.
1236  unsigned Delta = 2;
1237  // Compute the offset where the CPE will begin.
1238  unsigned CPEOffset = UserBBI.postOffset(CPELogAlign) + Delta;
1239 
1240  if (isOffsetInRange(UserOffset, CPEOffset, U)) {
1241  LLVM_DEBUG(dbgs() << "Split at end of " << printMBBReference(*UserMBB)
1242  << format(", expected CPE offset %#x\n", CPEOffset));
1243  NewMBB = &*++UserMBB->getIterator();
1244  // Add an unconditional branch from UserMBB to fallthrough block. Record
1245  // it for branch lengthening; this new branch will not get out of range,
1246  // but if the preceding conditional branch is out of range, the targets
1247  // will be exchanged, and the altered branch may be out of range, so the
1248  // machinery has to know about it.
1249  int UncondBr = Mips::Bimm16;
1250  BuildMI(UserMBB, DebugLoc(), TII->get(UncondBr)).addMBB(NewMBB);
1251  unsigned MaxDisp = getUnconditionalBrDisp(UncondBr);
1252  ImmBranches.push_back(ImmBranch(&UserMBB->back(),
1253  MaxDisp, false, UncondBr));
1254  BBInfo[UserMBB->getNumber()].Size += Delta;
1255  adjustBBOffsetsAfter(UserMBB);
1256  return;
1257  }
1258  }
1259 
1260  // What a big block. Find a place within the block to split it.
1261 
1262  // Try to split the block so it's fully aligned. Compute the latest split
1263  // point where we can add a 4-byte branch instruction, and then align to
1264  // LogAlign which is the largest possible alignment in the function.
1265  unsigned LogAlign = MF->getAlignment();
1266  assert(LogAlign >= CPELogAlign && "Over-aligned constant pool entry");
1267  unsigned BaseInsertOffset = UserOffset + U.getMaxDisp();
1268  LLVM_DEBUG(dbgs() << format("Split in middle of big block before %#x",
1269  BaseInsertOffset));
1270 
1271  // The 4 in the following is for the unconditional branch we'll be inserting
1272  // Alignment of the island is handled
1273  // inside isOffsetInRange.
1274  BaseInsertOffset -= 4;
1275 
1276  LLVM_DEBUG(dbgs() << format(", adjusted to %#x", BaseInsertOffset)
1277  << " la=" << LogAlign << '\n');
1278 
1279  // This could point off the end of the block if we've already got constant
1280  // pool entries following this block; only the last one is in the water list.
1281  // Back past any possible branches (allow for a conditional and a maximally
1282  // long unconditional).
1283  if (BaseInsertOffset + 8 >= UserBBI.postOffset()) {
1284  BaseInsertOffset = UserBBI.postOffset() - 8;
1285  LLVM_DEBUG(dbgs() << format("Move inside block: %#x\n", BaseInsertOffset));
1286  }
1287  unsigned EndInsertOffset = BaseInsertOffset + 4 +
1288  CPEMI->getOperand(2).getImm();
1289  MachineBasicBlock::iterator MI = UserMI;
1290  ++MI;
1291  unsigned CPUIndex = CPUserIndex+1;
1292  unsigned NumCPUsers = CPUsers.size();
1293  //MachineInstr *LastIT = 0;
1294  for (unsigned Offset = UserOffset + TII->getInstSizeInBytes(*UserMI);
1295  Offset < BaseInsertOffset;
1296  Offset += TII->getInstSizeInBytes(*MI), MI = std::next(MI)) {
1297  assert(MI != UserMBB->end() && "Fell off end of block");
1298  if (CPUIndex < NumCPUsers && CPUsers[CPUIndex].MI == MI) {
1299  CPUser &U = CPUsers[CPUIndex];
1300  if (!isOffsetInRange(Offset, EndInsertOffset, U)) {
1301  // Shift intertion point by one unit of alignment so it is within reach.
1302  BaseInsertOffset -= 1u << LogAlign;
1303  EndInsertOffset -= 1u << LogAlign;
1304  }
1305  // This is overly conservative, as we don't account for CPEMIs being
1306  // reused within the block, but it doesn't matter much. Also assume CPEs
1307  // are added in order with alignment padding. We may eventually be able
1308  // to pack the aligned CPEs better.
1309  EndInsertOffset += U.CPEMI->getOperand(2).getImm();
1310  CPUIndex++;
1311  }
1312  }
1313 
1314  NewMBB = splitBlockBeforeInstr(*--MI);
1315 }
1316 
1317 /// handleConstantPoolUser - Analyze the specified user, checking to see if it
1318 /// is out-of-range. If so, pick up the constant pool value and move it some
1319 /// place in-range. Return true if we changed any addresses (thus must run
1320 /// another pass of branch lengthening), false otherwise.
1321 bool MipsConstantIslands::handleConstantPoolUser(unsigned CPUserIndex) {
1322  CPUser &U = CPUsers[CPUserIndex];
1323  MachineInstr *UserMI = U.MI;
1324  MachineInstr *CPEMI = U.CPEMI;
1325  unsigned CPI = CPEMI->getOperand(1).getIndex();
1326  unsigned Size = CPEMI->getOperand(2).getImm();
1327  // Compute this only once, it's expensive.
1328  unsigned UserOffset = getUserOffset(U);
1329 
1330  // See if the current entry is within range, or there is a clone of it
1331  // in range.
1332  int result = findInRangeCPEntry(U, UserOffset);
1333  if (result==1) return false;
1334  else if (result==2) return true;
1335 
1336  // Look for water where we can place this CPE.
1337  MachineBasicBlock *NewIsland = MF->CreateMachineBasicBlock();
1338  MachineBasicBlock *NewMBB;
1339  water_iterator IP;
1340  if (findAvailableWater(U, UserOffset, IP)) {
1341  LLVM_DEBUG(dbgs() << "Found water in range\n");
1342  MachineBasicBlock *WaterBB = *IP;
1343 
1344  // If the original WaterList entry was "new water" on this iteration,
1345  // propagate that to the new island. This is just keeping NewWaterList
1346  // updated to match the WaterList, which will be updated below.
1347  if (NewWaterList.erase(WaterBB))
1348  NewWaterList.insert(NewIsland);
1349 
1350  // The new CPE goes before the following block (NewMBB).
1351  NewMBB = &*++WaterBB->getIterator();
1352  } else {
1353  // No water found.
1354  // we first see if a longer form of the instrucion could have reached
1355  // the constant. in that case we won't bother to split
1356  if (!NoLoadRelaxation) {
1357  result = findLongFormInRangeCPEntry(U, UserOffset);
1358  if (result != 0) return true;
1359  }
1360  LLVM_DEBUG(dbgs() << "No water found\n");
1361  createNewWater(CPUserIndex, UserOffset, NewMBB);
1362 
1363  // splitBlockBeforeInstr adds to WaterList, which is important when it is
1364  // called while handling branches so that the water will be seen on the
1365  // next iteration for constant pools, but in this context, we don't want
1366  // it. Check for this so it will be removed from the WaterList.
1367  // Also remove any entry from NewWaterList.
1368  MachineBasicBlock *WaterBB = &*--NewMBB->getIterator();
1369  IP = llvm::find(WaterList, WaterBB);
1370  if (IP != WaterList.end())
1371  NewWaterList.erase(WaterBB);
1372 
1373  // We are adding new water. Update NewWaterList.
1374  NewWaterList.insert(NewIsland);
1375  }
1376 
1377  // Remove the original WaterList entry; we want subsequent insertions in
1378  // this vicinity to go after the one we're about to insert. This
1379  // considerably reduces the number of times we have to move the same CPE
1380  // more than once and is also important to ensure the algorithm terminates.
1381  if (IP != WaterList.end())
1382  WaterList.erase(IP);
1383 
1384  // Okay, we know we can put an island before NewMBB now, do it!
1385  MF->insert(NewMBB->getIterator(), NewIsland);
1386 
1387  // Update internal data structures to account for the newly inserted MBB.
1388  updateForInsertedWaterBlock(NewIsland);
1389 
1390  // Decrement the old entry, and remove it if refcount becomes 0.
1391  decrementCPEReferenceCount(CPI, CPEMI);
1392 
1393  // No existing clone of this CPE is within range.
1394  // We will be generating a new clone. Get a UID for it.
1395  unsigned ID = createPICLabelUId();
1396 
1397  // Now that we have an island to add the CPE to, clone the original CPE and
1398  // add it to the island.
1399  U.HighWaterMark = NewIsland;
1400  U.CPEMI = BuildMI(NewIsland, DebugLoc(), TII->get(Mips::CONSTPOOL_ENTRY))
1401  .addImm(ID).addConstantPoolIndex(CPI).addImm(Size);
1402  CPEntries[CPI].push_back(CPEntry(U.CPEMI, ID, 1));
1403  ++NumCPEs;
1404 
1405  // Mark the basic block as aligned as required by the const-pool entry.
1406  NewIsland->setAlignment(getCPELogAlign(*U.CPEMI));
1407 
1408  // Increase the size of the island block to account for the new entry.
1409  BBInfo[NewIsland->getNumber()].Size += Size;
1410  adjustBBOffsetsAfter(&*--NewIsland->getIterator());
1411 
1412  // Finally, change the CPI in the instruction operand to be ID.
1413  for (unsigned i = 0, e = UserMI->getNumOperands(); i != e; ++i)
1414  if (UserMI->getOperand(i).isCPI()) {
1415  UserMI->getOperand(i).setIndex(ID);
1416  break;
1417  }
1418 
1419  LLVM_DEBUG(
1420  dbgs() << " Moved CPE to #" << ID << " CPI=" << CPI
1421  << format(" offset=%#x\n", BBInfo[NewIsland->getNumber()].Offset));
1422 
1423  return true;
1424 }
1425 
1426 /// removeDeadCPEMI - Remove a dead constant pool entry instruction. Update
1427 /// sizes and offsets of impacted basic blocks.
1428 void MipsConstantIslands::removeDeadCPEMI(MachineInstr *CPEMI) {
1429  MachineBasicBlock *CPEBB = CPEMI->getParent();
1430  unsigned Size = CPEMI->getOperand(2).getImm();
1431  CPEMI->eraseFromParent();
1432  BBInfo[CPEBB->getNumber()].Size -= Size;
1433  // All succeeding offsets have the current size value added in, fix this.
1434  if (CPEBB->empty()) {
1435  BBInfo[CPEBB->getNumber()].Size = 0;
1436 
1437  // This block no longer needs to be aligned.
1438  CPEBB->setAlignment(0);
1439  } else
1440  // Entries are sorted by descending alignment, so realign from the front.
1441  CPEBB->setAlignment(getCPELogAlign(*CPEBB->begin()));
1442 
1443  adjustBBOffsetsAfter(CPEBB);
1444  // An island has only one predecessor BB and one successor BB. Check if
1445  // this BB's predecessor jumps directly to this BB's successor. This
1446  // shouldn't happen currently.
1447  assert(!BBIsJumpedOver(CPEBB) && "How did this happen?");
1448  // FIXME: remove the empty blocks after all the work is done?
1449 }
1450 
1451 /// removeUnusedCPEntries - Remove constant pool entries whose refcounts
1452 /// are zero.
1453 bool MipsConstantIslands::removeUnusedCPEntries() {
1454  unsigned MadeChange = false;
1455  for (unsigned i = 0, e = CPEntries.size(); i != e; ++i) {
1456  std::vector<CPEntry> &CPEs = CPEntries[i];
1457  for (unsigned j = 0, ee = CPEs.size(); j != ee; ++j) {
1458  if (CPEs[j].RefCount == 0 && CPEs[j].CPEMI) {
1459  removeDeadCPEMI(CPEs[j].CPEMI);
1460  CPEs[j].CPEMI = nullptr;
1461  MadeChange = true;
1462  }
1463  }
1464  }
1465  return MadeChange;
1466 }
1467 
1468 /// isBBInRange - Returns true if the distance between specific MI and
1469 /// specific BB can fit in MI's displacement field.
1470 bool MipsConstantIslands::isBBInRange
1471  (MachineInstr *MI,MachineBasicBlock *DestBB, unsigned MaxDisp) {
1472  unsigned PCAdj = 4;
1473  unsigned BrOffset = getOffsetOf(MI) + PCAdj;
1474  unsigned DestOffset = BBInfo[DestBB->getNumber()].Offset;
1475 
1476  LLVM_DEBUG(dbgs() << "Branch of destination " << printMBBReference(*DestBB)
1477  << " from " << printMBBReference(*MI->getParent())
1478  << " max delta=" << MaxDisp << " from " << getOffsetOf(MI)
1479  << " to " << DestOffset << " offset "
1480  << int(DestOffset - BrOffset) << "\t" << *MI);
1481 
1482  if (BrOffset <= DestOffset) {
1483  // Branch before the Dest.
1484  if (DestOffset-BrOffset <= MaxDisp)
1485  return true;
1486  } else {
1487  if (BrOffset-DestOffset <= MaxDisp)
1488  return true;
1489  }
1490  return false;
1491 }
1492 
1493 /// fixupImmediateBr - Fix up an immediate branch whose destination is too far
1494 /// away to fit in its displacement field.
1495 bool MipsConstantIslands::fixupImmediateBr(ImmBranch &Br) {
1496  MachineInstr *MI = Br.MI;
1497  unsigned TargetOperand = branchTargetOperand(MI);
1498  MachineBasicBlock *DestBB = MI->getOperand(TargetOperand).getMBB();
1499 
1500  // Check to see if the DestBB is already in-range.
1501  if (isBBInRange(MI, DestBB, Br.MaxDisp))
1502  return false;
1503 
1504  if (!Br.isCond)
1505  return fixupUnconditionalBr(Br);
1506  return fixupConditionalBr(Br);
1507 }
1508 
1509 /// fixupUnconditionalBr - Fix up an unconditional branch whose destination is
1510 /// too far away to fit in its displacement field. If the LR register has been
1511 /// spilled in the epilogue, then we can use BL to implement a far jump.
1512 /// Otherwise, add an intermediate branch instruction to a branch.
1513 bool
1514 MipsConstantIslands::fixupUnconditionalBr(ImmBranch &Br) {
1515  MachineInstr *MI = Br.MI;
1516  MachineBasicBlock *MBB = MI->getParent();
1517  MachineBasicBlock *DestBB = MI->getOperand(0).getMBB();
1518  // Use BL to implement far jump.
1519  unsigned BimmX16MaxDisp = ((1 << 16)-1) * 2;
1520  if (isBBInRange(MI, DestBB, BimmX16MaxDisp)) {
1521  Br.MaxDisp = BimmX16MaxDisp;
1522  MI->setDesc(TII->get(Mips::BimmX16));
1523  }
1524  else {
1525  // need to give the math a more careful look here
1526  // this is really a segment address and not
1527  // a PC relative address. FIXME. But I think that
1528  // just reducing the bits by 1 as I've done is correct.
1529  // The basic block we are branching too much be longword aligned.
1530  // we know that RA is saved because we always save it right now.
1531  // this requirement will be relaxed later but we also have an alternate
1532  // way to implement this that I will implement that does not need jal.
1533  // We should have a way to back out this alignment restriction if we "can" later.
1534  // but it is not harmful.
1535  //
1536  DestBB->setAlignment(2);
1537  Br.MaxDisp = ((1<<24)-1) * 2;
1538  MI->setDesc(TII->get(Mips::JalB16));
1539  }
1540  BBInfo[MBB->getNumber()].Size += 2;
1541  adjustBBOffsetsAfter(MBB);
1542  HasFarJump = true;
1543  ++NumUBrFixed;
1544 
1545  LLVM_DEBUG(dbgs() << " Changed B to long jump " << *MI);
1546 
1547  return true;
1548 }
1549 
1550 /// fixupConditionalBr - Fix up a conditional branch whose destination is too
1551 /// far away to fit in its displacement field. It is converted to an inverse
1552 /// conditional branch + an unconditional branch to the destination.
1553 bool
1554 MipsConstantIslands::fixupConditionalBr(ImmBranch &Br) {
1555  MachineInstr *MI = Br.MI;
1556  unsigned TargetOperand = branchTargetOperand(MI);
1557  MachineBasicBlock *DestBB = MI->getOperand(TargetOperand).getMBB();
1558  unsigned Opcode = MI->getOpcode();
1559  unsigned LongFormOpcode = longformBranchOpcode(Opcode);
1560  unsigned LongFormMaxOff = branchMaxOffsets(LongFormOpcode);
1561 
1562  // Check to see if the DestBB is already in-range.
1563  if (isBBInRange(MI, DestBB, LongFormMaxOff)) {
1564  Br.MaxDisp = LongFormMaxOff;
1565  MI->setDesc(TII->get(LongFormOpcode));
1566  return true;
1567  }
1568 
1569  // Add an unconditional branch to the destination and invert the branch
1570  // condition to jump over it:
1571  // bteqz L1
1572  // =>
1573  // bnez L2
1574  // b L1
1575  // L2:
1576 
1577  // If the branch is at the end of its MBB and that has a fall-through block,
1578  // direct the updated conditional branch to the fall-through block. Otherwise,
1579  // split the MBB before the next instruction.
1580  MachineBasicBlock *MBB = MI->getParent();
1581  MachineInstr *BMI = &MBB->back();
1582  bool NeedSplit = (BMI != MI) || !BBHasFallthrough(MBB);
1583  unsigned OppositeBranchOpcode = TII->getOppositeBranchOpc(Opcode);
1584 
1585  ++NumCBrFixed;
1586  if (BMI != MI) {
1587  if (std::next(MachineBasicBlock::iterator(MI)) == std::prev(MBB->end()) &&
1588  BMI->isUnconditionalBranch()) {
1589  // Last MI in the BB is an unconditional branch. Can we simply invert the
1590  // condition and swap destinations:
1591  // beqz L1
1592  // b L2
1593  // =>
1594  // bnez L2
1595  // b L1
1596  unsigned BMITargetOperand = branchTargetOperand(BMI);
1597  MachineBasicBlock *NewDest =
1598  BMI->getOperand(BMITargetOperand).getMBB();
1599  if (isBBInRange(MI, NewDest, Br.MaxDisp)) {
1600  LLVM_DEBUG(
1601  dbgs() << " Invert Bcc condition and swap its destination with "
1602  << *BMI);
1603  MI->setDesc(TII->get(OppositeBranchOpcode));
1604  BMI->getOperand(BMITargetOperand).setMBB(DestBB);
1605  MI->getOperand(TargetOperand).setMBB(NewDest);
1606  return true;
1607  }
1608  }
1609  }
1610 
1611  if (NeedSplit) {
1612  splitBlockBeforeInstr(*MI);
1613  // No need for the branch to the next block. We're adding an unconditional
1614  // branch to the destination.
1615  int delta = TII->getInstSizeInBytes(MBB->back());
1616  BBInfo[MBB->getNumber()].Size -= delta;
1617  MBB->back().eraseFromParent();
1618  // BBInfo[SplitBB].Offset is wrong temporarily, fixed below
1619  }
1620  MachineBasicBlock *NextBB = &*++MBB->getIterator();
1621 
1622  LLVM_DEBUG(dbgs() << " Insert B to " << printMBBReference(*DestBB)
1623  << " also invert condition and change dest. to "
1624  << printMBBReference(*NextBB) << "\n");
1625 
1626  // Insert a new conditional branch and a new unconditional branch.
1627  // Also update the ImmBranch as well as adding a new entry for the new branch.
1628  if (MI->getNumExplicitOperands() == 2) {
1629  BuildMI(MBB, DebugLoc(), TII->get(OppositeBranchOpcode))
1630  .addReg(MI->getOperand(0).getReg())
1631  .addMBB(NextBB);
1632  } else {
1633  BuildMI(MBB, DebugLoc(), TII->get(OppositeBranchOpcode))
1634  .addMBB(NextBB);
1635  }
1636  Br.MI = &MBB->back();
1637  BBInfo[MBB->getNumber()].Size += TII->getInstSizeInBytes(MBB->back());
1638  BuildMI(MBB, DebugLoc(), TII->get(Br.UncondBr)).addMBB(DestBB);
1639  BBInfo[MBB->getNumber()].Size += TII->getInstSizeInBytes(MBB->back());
1640  unsigned MaxDisp = getUnconditionalBrDisp(Br.UncondBr);
1641  ImmBranches.push_back(ImmBranch(&MBB->back(), MaxDisp, false, Br.UncondBr));
1642 
1643  // Remove the old conditional branch. It may or may not still be in MBB.
1644  BBInfo[MI->getParent()->getNumber()].Size -= TII->getInstSizeInBytes(*MI);
1645  MI->eraseFromParent();
1646  adjustBBOffsetsAfter(MBB);
1647  return true;
1648 }
1649 
1650 void MipsConstantIslands::prescanForConstants() {
1651  unsigned J = 0;
1652  (void)J;
1654  MF->begin(), E = MF->end(); B != E; ++B) {
1656  B->instr_begin(), EB = B->instr_end(); I != EB; ++I) {
1657  switch(I->getDesc().getOpcode()) {
1658  case Mips::LwConstant32: {
1659  PrescannedForConstants = true;
1660  LLVM_DEBUG(dbgs() << "constant island constant " << *I << "\n");
1661  J = I->getNumOperands();
1662  LLVM_DEBUG(dbgs() << "num operands " << J << "\n");
1663  MachineOperand& Literal = I->getOperand(1);
1664  if (Literal.isImm()) {
1665  int64_t V = Literal.getImm();
1666  LLVM_DEBUG(dbgs() << "literal " << V << "\n");
1667  Type *Int32Ty =
1668  Type::getInt32Ty(MF->getFunction().getContext());
1669  const Constant *C = ConstantInt::get(Int32Ty, V);
1670  unsigned index = MCP->getConstantPoolIndex(C, 4);
1671  I->getOperand(2).ChangeToImmediate(index);
1672  LLVM_DEBUG(dbgs() << "constant island constant " << *I << "\n");
1673  I->setDesc(TII->get(Mips::LwRxPcTcp16));
1674  I->RemoveOperand(1);
1675  I->RemoveOperand(1);
1676  I->addOperand(MachineOperand::CreateCPI(index, 0));
1677  I->addOperand(MachineOperand::CreateImm(4));
1678  }
1679  break;
1680  }
1681  default:
1682  break;
1683  }
1684  }
1685  }
1686 }
1687 
1688 /// Returns a pass that converts branches to long branches.
1690  return new MipsConstantIslands();
1691 }
auto lower_bound(R &&Range, T &&Value) -> decltype(adl_begin(Range))
Provide wrappers to std::lower_bound which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:1281
uint64_t CallInst * C
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:110
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:139
This class represents lattice values for constants.
Definition: AllocatorList.h:23
#define LLVM_DUMP_METHOD
Mark debug helper function definitions like dump() that should not be stripped from debug builds...
Definition: Compiler.h:473
void RenumberBlocks(MachineBasicBlock *MBBFrom=nullptr)
RenumberBlocks - This discards all of the MachineBasicBlock numbers and recomputes them...
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:123
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:33
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
Printable printMBBReference(const MachineBasicBlock &MBB)
Prints a machine basic block reference.
unsigned getNumOperands() const
Retuns the total number of operands.
Definition: MachineInstr.h:411
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:408
MachineInstrBundleIterator< MachineInstr, true > reverse_iterator
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:432
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:428
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
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:41
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:134
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:284
FunctionPass * createMipsConstantIslandPass()
Returns a pass that converts branches to long branches.
self_iterator getIterator()
Definition: ilist_node.h:81
MachineConstantPool * getConstantPool()
getConstantPool - Return the constant pool object for the current function.
size_t size() const
Definition: SmallVector.h:52
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:1206
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...
auto size(R &&Range, typename std::enable_if< std::is_same< typename std::iterator_traits< decltype(Range.begin())>::iterator_category, std::random_access_iterator_tag >::value, void >::type *=nullptr) -> decltype(std::distance(Range.begin(), Range.end()))
Get the size of a range.
Definition: STLExtras.h:1166
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:841
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:1218
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:631
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:538
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:678
unsigned succ_size() const
const MachineBasicBlock * getParent() const
Definition: MachineInstr.h:253
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:461
Representation of each machine instruction.
Definition: MachineInstr.h:63
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:175
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...
uint32_t Size
Definition: Profile.cpp:46
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
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:726
IRTranslator LLVM IR MI
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48
#define LLVM_DEBUG(X)
Definition: Debug.h:122
const MachineOperand & getOperand(unsigned i) const
Definition: MachineInstr.h:413
std::vector< MachineBasicBlock * >::iterator succ_iterator
Properties which a MachineFunction may have at a given point in time.
IntegerType * Int32Ty