LLVM  10.0.0svn
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 
390  void computeBlockSize(MachineBasicBlock *MBB);
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.
796 void MipsConstantIslands::computeBlockSize(MachineBasicBlock *MBB) {
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 = llvm::lower_bound(WaterList, NewBB, CompareMBBNumbers);
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 = llvm::lower_bound(WaterList, OrigBB, CompareMBBNumbers);
895  MachineBasicBlock* WaterBB = *IP;
896  if (WaterBB == OrigBB)
897  WaterList.insert(std::next(IP), NewBB);
898  else
899  WaterList.insert(IP, OrigBB);
900  NewWaterList.insert(OrigBB);
901 
902  // Figure out how large the OrigBB is. As the first half of the original
903  // block, it cannot contain a tablejump. The size includes
904  // the new jump we added. (It should be possible to do this without
905  // recounting everything, but it's very confusing, and this is rarely
906  // executed.)
907  computeBlockSize(OrigBB);
908 
909  // Figure out how large the NewMBB is. As the second half of the original
910  // block, it may contain a tablejump.
911  computeBlockSize(NewBB);
912 
913  // All BBOffsets following these blocks must be modified.
914  adjustBBOffsetsAfter(OrigBB);
915 
916  return NewBB;
917 }
918 
919 /// isOffsetInRange - Checks whether UserOffset (the location of a constant pool
920 /// reference) is within MaxDisp of TrialOffset (a proposed location of a
921 /// constant pool entry).
922 bool MipsConstantIslands::isOffsetInRange(unsigned UserOffset,
923  unsigned TrialOffset, unsigned MaxDisp,
924  bool NegativeOK) {
925  if (UserOffset <= TrialOffset) {
926  // User before the Trial.
927  if (TrialOffset - UserOffset <= MaxDisp)
928  return true;
929  } else if (NegativeOK) {
930  if (UserOffset - TrialOffset <= MaxDisp)
931  return true;
932  }
933  return false;
934 }
935 
936 /// isWaterInRange - Returns true if a CPE placed after the specified
937 /// Water (a basic block) will be in range for the specific MI.
938 ///
939 /// Compute how much the function will grow by inserting a CPE after Water.
940 bool MipsConstantIslands::isWaterInRange(unsigned UserOffset,
941  MachineBasicBlock* Water, CPUser &U,
942  unsigned &Growth) {
943  unsigned CPELogAlign = getCPELogAlign(*U.CPEMI);
944  unsigned CPEOffset = BBInfo[Water->getNumber()].postOffset(CPELogAlign);
945  unsigned NextBlockOffset, NextBlockAlignment;
946  MachineFunction::const_iterator NextBlock = ++Water->getIterator();
947  if (NextBlock == MF->end()) {
948  NextBlockOffset = BBInfo[Water->getNumber()].postOffset();
949  NextBlockAlignment = 0;
950  } else {
951  NextBlockOffset = BBInfo[NextBlock->getNumber()].Offset;
952  NextBlockAlignment = NextBlock->getAlignment();
953  }
954  unsigned Size = U.CPEMI->getOperand(2).getImm();
955  unsigned CPEEnd = CPEOffset + Size;
956 
957  // The CPE may be able to hide in the alignment padding before the next
958  // block. It may also cause more padding to be required if it is more aligned
959  // that the next block.
960  if (CPEEnd > NextBlockOffset) {
961  Growth = CPEEnd - NextBlockOffset;
962  // Compute the padding that would go at the end of the CPE to align the next
963  // block.
964  Growth += OffsetToAlignment(CPEEnd, 1ULL << NextBlockAlignment);
965 
966  // If the CPE is to be inserted before the instruction, that will raise
967  // the offset of the instruction. Also account for unknown alignment padding
968  // in blocks between CPE and the user.
969  if (CPEOffset < UserOffset)
970  UserOffset += Growth;
971  } else
972  // CPE fits in existing padding.
973  Growth = 0;
974 
975  return isOffsetInRange(UserOffset, CPEOffset, U);
976 }
977 
978 /// isCPEntryInRange - Returns true if the distance between specific MI and
979 /// specific ConstPool entry instruction can fit in MI's displacement field.
980 bool MipsConstantIslands::isCPEntryInRange
981  (MachineInstr *MI, unsigned UserOffset,
982  MachineInstr *CPEMI, unsigned MaxDisp,
983  bool NegOk, bool DoDump) {
984  unsigned CPEOffset = getOffsetOf(CPEMI);
985 
986  if (DoDump) {
987  LLVM_DEBUG({
988  unsigned Block = MI->getParent()->getNumber();
989  const BasicBlockInfo &BBI = BBInfo[Block];
990  dbgs() << "User of CPE#" << CPEMI->getOperand(0).getImm()
991  << " max delta=" << MaxDisp
992  << format(" insn address=%#x", UserOffset) << " in "
993  << printMBBReference(*MI->getParent()) << ": "
994  << format("%#x-%x\t", BBI.Offset, BBI.postOffset()) << *MI
995  << format("CPE address=%#x offset=%+d: ", CPEOffset,
996  int(CPEOffset - UserOffset));
997  });
998  }
999 
1000  return isOffsetInRange(UserOffset, CPEOffset, MaxDisp, NegOk);
1001 }
1002 
1003 #ifndef NDEBUG
1004 /// BBIsJumpedOver - Return true of the specified basic block's only predecessor
1005 /// unconditionally branches to its only successor.
1007  if (MBB->pred_size() != 1 || MBB->succ_size() != 1)
1008  return false;
1009  MachineBasicBlock *Succ = *MBB->succ_begin();
1010  MachineBasicBlock *Pred = *MBB->pred_begin();
1011  MachineInstr *PredMI = &Pred->back();
1012  if (PredMI->getOpcode() == Mips::Bimm16)
1013  return PredMI->getOperand(0).getMBB() == Succ;
1014  return false;
1015 }
1016 #endif
1017 
1018 void MipsConstantIslands::adjustBBOffsetsAfter(MachineBasicBlock *BB) {
1019  unsigned BBNum = BB->getNumber();
1020  for(unsigned i = BBNum + 1, e = MF->getNumBlockIDs(); i < e; ++i) {
1021  // Get the offset and known bits at the end of the layout predecessor.
1022  // Include the alignment of the current block.
1023  unsigned Offset = BBInfo[i - 1].Offset + BBInfo[i - 1].Size;
1024  BBInfo[i].Offset = Offset;
1025  }
1026 }
1027 
1028 /// decrementCPEReferenceCount - find the constant pool entry with index CPI
1029 /// and instruction CPEMI, and decrement its refcount. If the refcount
1030 /// becomes 0 remove the entry and instruction. Returns true if we removed
1031 /// the entry, false if we didn't.
1032 bool MipsConstantIslands::decrementCPEReferenceCount(unsigned CPI,
1033  MachineInstr *CPEMI) {
1034  // Find the old entry. Eliminate it if it is no longer used.
1035  CPEntry *CPE = findConstPoolEntry(CPI, CPEMI);
1036  assert(CPE && "Unexpected!");
1037  if (--CPE->RefCount == 0) {
1038  removeDeadCPEMI(CPEMI);
1039  CPE->CPEMI = nullptr;
1040  --NumCPEs;
1041  return true;
1042  }
1043  return false;
1044 }
1045 
1046 /// LookForCPEntryInRange - see if the currently referenced CPE is in range;
1047 /// if not, see if an in-range clone of the CPE is in range, and if so,
1048 /// change the data structures so the user references the clone. Returns:
1049 /// 0 = no existing entry found
1050 /// 1 = entry found, and there were no code insertions or deletions
1051 /// 2 = entry found, and there were code insertions or deletions
1052 int MipsConstantIslands::findInRangeCPEntry(CPUser& U, unsigned UserOffset)
1053 {
1054  MachineInstr *UserMI = U.MI;
1055  MachineInstr *CPEMI = U.CPEMI;
1056 
1057  // Check to see if the CPE is already in-range.
1058  if (isCPEntryInRange(UserMI, UserOffset, CPEMI, U.getMaxDisp(), U.NegOk,
1059  true)) {
1060  LLVM_DEBUG(dbgs() << "In range\n");
1061  return 1;
1062  }
1063 
1064  // No. Look for previously created clones of the CPE that are in range.
1065  unsigned CPI = CPEMI->getOperand(1).getIndex();
1066  std::vector<CPEntry> &CPEs = CPEntries[CPI];
1067  for (unsigned i = 0, e = CPEs.size(); i != e; ++i) {
1068  // We already tried this one
1069  if (CPEs[i].CPEMI == CPEMI)
1070  continue;
1071  // Removing CPEs can leave empty entries, skip
1072  if (CPEs[i].CPEMI == nullptr)
1073  continue;
1074  if (isCPEntryInRange(UserMI, UserOffset, CPEs[i].CPEMI, U.getMaxDisp(),
1075  U.NegOk)) {
1076  LLVM_DEBUG(dbgs() << "Replacing CPE#" << CPI << " with CPE#"
1077  << CPEs[i].CPI << "\n");
1078  // Point the CPUser node to the replacement
1079  U.CPEMI = CPEs[i].CPEMI;
1080  // Change the CPI in the instruction operand to refer to the clone.
1081  for (unsigned j = 0, e = UserMI->getNumOperands(); j != e; ++j)
1082  if (UserMI->getOperand(j).isCPI()) {
1083  UserMI->getOperand(j).setIndex(CPEs[i].CPI);
1084  break;
1085  }
1086  // Adjust the refcount of the clone...
1087  CPEs[i].RefCount++;
1088  // ...and the original. If we didn't remove the old entry, none of the
1089  // addresses changed, so we don't need another pass.
1090  return decrementCPEReferenceCount(CPI, CPEMI) ? 2 : 1;
1091  }
1092  }
1093  return 0;
1094 }
1095 
1096 /// LookForCPEntryInRange - see if the currently referenced CPE is in range;
1097 /// This version checks if the longer form of the instruction can be used to
1098 /// to satisfy things.
1099 /// if not, see if an in-range clone of the CPE is in range, and if so,
1100 /// change the data structures so the user references the clone. Returns:
1101 /// 0 = no existing entry found
1102 /// 1 = entry found, and there were no code insertions or deletions
1103 /// 2 = entry found, and there were code insertions or deletions
1104 int MipsConstantIslands::findLongFormInRangeCPEntry
1105  (CPUser& U, unsigned UserOffset)
1106 {
1107  MachineInstr *UserMI = U.MI;
1108  MachineInstr *CPEMI = U.CPEMI;
1109 
1110  // Check to see if the CPE is already in-range.
1111  if (isCPEntryInRange(UserMI, UserOffset, CPEMI,
1112  U.getLongFormMaxDisp(), U.NegOk,
1113  true)) {
1114  LLVM_DEBUG(dbgs() << "In range\n");
1115  UserMI->setDesc(TII->get(U.getLongFormOpcode()));
1116  U.setMaxDisp(U.getLongFormMaxDisp());
1117  return 2; // instruction is longer length now
1118  }
1119 
1120  // No. Look for previously created clones of the CPE that are in range.
1121  unsigned CPI = CPEMI->getOperand(1).getIndex();
1122  std::vector<CPEntry> &CPEs = CPEntries[CPI];
1123  for (unsigned i = 0, e = CPEs.size(); i != e; ++i) {
1124  // We already tried this one
1125  if (CPEs[i].CPEMI == CPEMI)
1126  continue;
1127  // Removing CPEs can leave empty entries, skip
1128  if (CPEs[i].CPEMI == nullptr)
1129  continue;
1130  if (isCPEntryInRange(UserMI, UserOffset, CPEs[i].CPEMI,
1131  U.getLongFormMaxDisp(), U.NegOk)) {
1132  LLVM_DEBUG(dbgs() << "Replacing CPE#" << CPI << " with CPE#"
1133  << CPEs[i].CPI << "\n");
1134  // Point the CPUser node to the replacement
1135  U.CPEMI = CPEs[i].CPEMI;
1136  // Change the CPI in the instruction operand to refer to the clone.
1137  for (unsigned j = 0, e = UserMI->getNumOperands(); j != e; ++j)
1138  if (UserMI->getOperand(j).isCPI()) {
1139  UserMI->getOperand(j).setIndex(CPEs[i].CPI);
1140  break;
1141  }
1142  // Adjust the refcount of the clone...
1143  CPEs[i].RefCount++;
1144  // ...and the original. If we didn't remove the old entry, none of the
1145  // addresses changed, so we don't need another pass.
1146  return decrementCPEReferenceCount(CPI, CPEMI) ? 2 : 1;
1147  }
1148  }
1149  return 0;
1150 }
1151 
1152 /// getUnconditionalBrDisp - Returns the maximum displacement that can fit in
1153 /// the specific unconditional branch instruction.
1154 static inline unsigned getUnconditionalBrDisp(int Opc) {
1155  switch (Opc) {
1156  case Mips::Bimm16:
1157  return ((1<<10)-1)*2;
1158  case Mips::BimmX16:
1159  return ((1<<16)-1)*2;
1160  default:
1161  break;
1162  }
1163  return ((1<<16)-1)*2;
1164 }
1165 
1166 /// findAvailableWater - Look for an existing entry in the WaterList in which
1167 /// we can place the CPE referenced from U so it's within range of U's MI.
1168 /// Returns true if found, false if not. If it returns true, WaterIter
1169 /// is set to the WaterList entry.
1170 /// To ensure that this pass
1171 /// terminates, the CPE location for a particular CPUser is only allowed to
1172 /// move to a lower address, so search backward from the end of the list and
1173 /// prefer the first water that is in range.
1174 bool MipsConstantIslands::findAvailableWater(CPUser &U, unsigned UserOffset,
1175  water_iterator &WaterIter) {
1176  if (WaterList.empty())
1177  return false;
1178 
1179  unsigned BestGrowth = ~0u;
1180  for (water_iterator IP = std::prev(WaterList.end()), B = WaterList.begin();;
1181  --IP) {
1182  MachineBasicBlock* WaterBB = *IP;
1183  // Check if water is in range and is either at a lower address than the
1184  // current "high water mark" or a new water block that was created since
1185  // the previous iteration by inserting an unconditional branch. In the
1186  // latter case, we want to allow resetting the high water mark back to
1187  // this new water since we haven't seen it before. Inserting branches
1188  // should be relatively uncommon and when it does happen, we want to be
1189  // sure to take advantage of it for all the CPEs near that block, so that
1190  // we don't insert more branches than necessary.
1191  unsigned Growth;
1192  if (isWaterInRange(UserOffset, WaterBB, U, Growth) &&
1193  (WaterBB->getNumber() < U.HighWaterMark->getNumber() ||
1194  NewWaterList.count(WaterBB)) && Growth < BestGrowth) {
1195  // This is the least amount of required padding seen so far.
1196  BestGrowth = Growth;
1197  WaterIter = IP;
1198  LLVM_DEBUG(dbgs() << "Found water after " << printMBBReference(*WaterBB)
1199  << " Growth=" << Growth << '\n');
1200 
1201  // Keep looking unless it is perfect.
1202  if (BestGrowth == 0)
1203  return true;
1204  }
1205  if (IP == B)
1206  break;
1207  }
1208  return BestGrowth != ~0u;
1209 }
1210 
1211 /// createNewWater - No existing WaterList entry will work for
1212 /// CPUsers[CPUserIndex], so create a place to put the CPE. The end of the
1213 /// block is used if in range, and the conditional branch munged so control
1214 /// flow is correct. Otherwise the block is split to create a hole with an
1215 /// unconditional branch around it. In either case NewMBB is set to a
1216 /// block following which the new island can be inserted (the WaterList
1217 /// is not adjusted).
1218 void MipsConstantIslands::createNewWater(unsigned CPUserIndex,
1219  unsigned UserOffset,
1220  MachineBasicBlock *&NewMBB) {
1221  CPUser &U = CPUsers[CPUserIndex];
1222  MachineInstr *UserMI = U.MI;
1223  MachineInstr *CPEMI = U.CPEMI;
1224  unsigned CPELogAlign = getCPELogAlign(*CPEMI);
1225  MachineBasicBlock *UserMBB = UserMI->getParent();
1226  const BasicBlockInfo &UserBBI = BBInfo[UserMBB->getNumber()];
1227 
1228  // If the block does not end in an unconditional branch already, and if the
1229  // end of the block is within range, make new water there.
1230  if (BBHasFallthrough(UserMBB)) {
1231  // Size of branch to insert.
1232  unsigned Delta = 2;
1233  // Compute the offset where the CPE will begin.
1234  unsigned CPEOffset = UserBBI.postOffset(CPELogAlign) + Delta;
1235 
1236  if (isOffsetInRange(UserOffset, CPEOffset, U)) {
1237  LLVM_DEBUG(dbgs() << "Split at end of " << printMBBReference(*UserMBB)
1238  << format(", expected CPE offset %#x\n", CPEOffset));
1239  NewMBB = &*++UserMBB->getIterator();
1240  // Add an unconditional branch from UserMBB to fallthrough block. Record
1241  // it for branch lengthening; this new branch will not get out of range,
1242  // but if the preceding conditional branch is out of range, the targets
1243  // will be exchanged, and the altered branch may be out of range, so the
1244  // machinery has to know about it.
1245  int UncondBr = Mips::Bimm16;
1246  BuildMI(UserMBB, DebugLoc(), TII->get(UncondBr)).addMBB(NewMBB);
1247  unsigned MaxDisp = getUnconditionalBrDisp(UncondBr);
1248  ImmBranches.push_back(ImmBranch(&UserMBB->back(),
1249  MaxDisp, false, UncondBr));
1250  BBInfo[UserMBB->getNumber()].Size += Delta;
1251  adjustBBOffsetsAfter(UserMBB);
1252  return;
1253  }
1254  }
1255 
1256  // What a big block. Find a place within the block to split it.
1257 
1258  // Try to split the block so it's fully aligned. Compute the latest split
1259  // point where we can add a 4-byte branch instruction, and then align to
1260  // LogAlign which is the largest possible alignment in the function.
1261  unsigned LogAlign = MF->getAlignment();
1262  assert(LogAlign >= CPELogAlign && "Over-aligned constant pool entry");
1263  unsigned BaseInsertOffset = UserOffset + U.getMaxDisp();
1264  LLVM_DEBUG(dbgs() << format("Split in middle of big block before %#x",
1265  BaseInsertOffset));
1266 
1267  // The 4 in the following is for the unconditional branch we'll be inserting
1268  // Alignment of the island is handled
1269  // inside isOffsetInRange.
1270  BaseInsertOffset -= 4;
1271 
1272  LLVM_DEBUG(dbgs() << format(", adjusted to %#x", BaseInsertOffset)
1273  << " la=" << LogAlign << '\n');
1274 
1275  // This could point off the end of the block if we've already got constant
1276  // pool entries following this block; only the last one is in the water list.
1277  // Back past any possible branches (allow for a conditional and a maximally
1278  // long unconditional).
1279  if (BaseInsertOffset + 8 >= UserBBI.postOffset()) {
1280  BaseInsertOffset = UserBBI.postOffset() - 8;
1281  LLVM_DEBUG(dbgs() << format("Move inside block: %#x\n", BaseInsertOffset));
1282  }
1283  unsigned EndInsertOffset = BaseInsertOffset + 4 +
1284  CPEMI->getOperand(2).getImm();
1285  MachineBasicBlock::iterator MI = UserMI;
1286  ++MI;
1287  unsigned CPUIndex = CPUserIndex+1;
1288  unsigned NumCPUsers = CPUsers.size();
1289  //MachineInstr *LastIT = 0;
1290  for (unsigned Offset = UserOffset + TII->getInstSizeInBytes(*UserMI);
1291  Offset < BaseInsertOffset;
1292  Offset += TII->getInstSizeInBytes(*MI), MI = std::next(MI)) {
1293  assert(MI != UserMBB->end() && "Fell off end of block");
1294  if (CPUIndex < NumCPUsers && CPUsers[CPUIndex].MI == MI) {
1295  CPUser &U = CPUsers[CPUIndex];
1296  if (!isOffsetInRange(Offset, EndInsertOffset, U)) {
1297  // Shift intertion point by one unit of alignment so it is within reach.
1298  BaseInsertOffset -= 1u << LogAlign;
1299  EndInsertOffset -= 1u << LogAlign;
1300  }
1301  // This is overly conservative, as we don't account for CPEMIs being
1302  // reused within the block, but it doesn't matter much. Also assume CPEs
1303  // are added in order with alignment padding. We may eventually be able
1304  // to pack the aligned CPEs better.
1305  EndInsertOffset += U.CPEMI->getOperand(2).getImm();
1306  CPUIndex++;
1307  }
1308  }
1309 
1310  NewMBB = splitBlockBeforeInstr(*--MI);
1311 }
1312 
1313 /// handleConstantPoolUser - Analyze the specified user, checking to see if it
1314 /// is out-of-range. If so, pick up the constant pool value and move it some
1315 /// place in-range. Return true if we changed any addresses (thus must run
1316 /// another pass of branch lengthening), false otherwise.
1317 bool MipsConstantIslands::handleConstantPoolUser(unsigned CPUserIndex) {
1318  CPUser &U = CPUsers[CPUserIndex];
1319  MachineInstr *UserMI = U.MI;
1320  MachineInstr *CPEMI = U.CPEMI;
1321  unsigned CPI = CPEMI->getOperand(1).getIndex();
1322  unsigned Size = CPEMI->getOperand(2).getImm();
1323  // Compute this only once, it's expensive.
1324  unsigned UserOffset = getUserOffset(U);
1325 
1326  // See if the current entry is within range, or there is a clone of it
1327  // in range.
1328  int result = findInRangeCPEntry(U, UserOffset);
1329  if (result==1) return false;
1330  else if (result==2) return true;
1331 
1332  // Look for water where we can place this CPE.
1333  MachineBasicBlock *NewIsland = MF->CreateMachineBasicBlock();
1334  MachineBasicBlock *NewMBB;
1335  water_iterator IP;
1336  if (findAvailableWater(U, UserOffset, IP)) {
1337  LLVM_DEBUG(dbgs() << "Found water in range\n");
1338  MachineBasicBlock *WaterBB = *IP;
1339 
1340  // If the original WaterList entry was "new water" on this iteration,
1341  // propagate that to the new island. This is just keeping NewWaterList
1342  // updated to match the WaterList, which will be updated below.
1343  if (NewWaterList.erase(WaterBB))
1344  NewWaterList.insert(NewIsland);
1345 
1346  // The new CPE goes before the following block (NewMBB).
1347  NewMBB = &*++WaterBB->getIterator();
1348  } else {
1349  // No water found.
1350  // we first see if a longer form of the instrucion could have reached
1351  // the constant. in that case we won't bother to split
1352  if (!NoLoadRelaxation) {
1353  result = findLongFormInRangeCPEntry(U, UserOffset);
1354  if (result != 0) return true;
1355  }
1356  LLVM_DEBUG(dbgs() << "No water found\n");
1357  createNewWater(CPUserIndex, UserOffset, NewMBB);
1358 
1359  // splitBlockBeforeInstr adds to WaterList, which is important when it is
1360  // called while handling branches so that the water will be seen on the
1361  // next iteration for constant pools, but in this context, we don't want
1362  // it. Check for this so it will be removed from the WaterList.
1363  // Also remove any entry from NewWaterList.
1364  MachineBasicBlock *WaterBB = &*--NewMBB->getIterator();
1365  IP = llvm::find(WaterList, WaterBB);
1366  if (IP != WaterList.end())
1367  NewWaterList.erase(WaterBB);
1368 
1369  // We are adding new water. Update NewWaterList.
1370  NewWaterList.insert(NewIsland);
1371  }
1372 
1373  // Remove the original WaterList entry; we want subsequent insertions in
1374  // this vicinity to go after the one we're about to insert. This
1375  // considerably reduces the number of times we have to move the same CPE
1376  // more than once and is also important to ensure the algorithm terminates.
1377  if (IP != WaterList.end())
1378  WaterList.erase(IP);
1379 
1380  // Okay, we know we can put an island before NewMBB now, do it!
1381  MF->insert(NewMBB->getIterator(), NewIsland);
1382 
1383  // Update internal data structures to account for the newly inserted MBB.
1384  updateForInsertedWaterBlock(NewIsland);
1385 
1386  // Decrement the old entry, and remove it if refcount becomes 0.
1387  decrementCPEReferenceCount(CPI, CPEMI);
1388 
1389  // No existing clone of this CPE is within range.
1390  // We will be generating a new clone. Get a UID for it.
1391  unsigned ID = createPICLabelUId();
1392 
1393  // Now that we have an island to add the CPE to, clone the original CPE and
1394  // add it to the island.
1395  U.HighWaterMark = NewIsland;
1396  U.CPEMI = BuildMI(NewIsland, DebugLoc(), TII->get(Mips::CONSTPOOL_ENTRY))
1397  .addImm(ID).addConstantPoolIndex(CPI).addImm(Size);
1398  CPEntries[CPI].push_back(CPEntry(U.CPEMI, ID, 1));
1399  ++NumCPEs;
1400 
1401  // Mark the basic block as aligned as required by the const-pool entry.
1402  NewIsland->setAlignment(getCPELogAlign(*U.CPEMI));
1403 
1404  // Increase the size of the island block to account for the new entry.
1405  BBInfo[NewIsland->getNumber()].Size += Size;
1406  adjustBBOffsetsAfter(&*--NewIsland->getIterator());
1407 
1408  // Finally, change the CPI in the instruction operand to be ID.
1409  for (unsigned i = 0, e = UserMI->getNumOperands(); i != e; ++i)
1410  if (UserMI->getOperand(i).isCPI()) {
1411  UserMI->getOperand(i).setIndex(ID);
1412  break;
1413  }
1414 
1415  LLVM_DEBUG(
1416  dbgs() << " Moved CPE to #" << ID << " CPI=" << CPI
1417  << format(" offset=%#x\n", BBInfo[NewIsland->getNumber()].Offset));
1418 
1419  return true;
1420 }
1421 
1422 /// removeDeadCPEMI - Remove a dead constant pool entry instruction. Update
1423 /// sizes and offsets of impacted basic blocks.
1424 void MipsConstantIslands::removeDeadCPEMI(MachineInstr *CPEMI) {
1425  MachineBasicBlock *CPEBB = CPEMI->getParent();
1426  unsigned Size = CPEMI->getOperand(2).getImm();
1427  CPEMI->eraseFromParent();
1428  BBInfo[CPEBB->getNumber()].Size -= Size;
1429  // All succeeding offsets have the current size value added in, fix this.
1430  if (CPEBB->empty()) {
1431  BBInfo[CPEBB->getNumber()].Size = 0;
1432 
1433  // This block no longer needs to be aligned.
1434  CPEBB->setAlignment(0);
1435  } else
1436  // Entries are sorted by descending alignment, so realign from the front.
1437  CPEBB->setAlignment(getCPELogAlign(*CPEBB->begin()));
1438 
1439  adjustBBOffsetsAfter(CPEBB);
1440  // An island has only one predecessor BB and one successor BB. Check if
1441  // this BB's predecessor jumps directly to this BB's successor. This
1442  // shouldn't happen currently.
1443  assert(!BBIsJumpedOver(CPEBB) && "How did this happen?");
1444  // FIXME: remove the empty blocks after all the work is done?
1445 }
1446 
1447 /// removeUnusedCPEntries - Remove constant pool entries whose refcounts
1448 /// are zero.
1449 bool MipsConstantIslands::removeUnusedCPEntries() {
1450  unsigned MadeChange = false;
1451  for (unsigned i = 0, e = CPEntries.size(); i != e; ++i) {
1452  std::vector<CPEntry> &CPEs = CPEntries[i];
1453  for (unsigned j = 0, ee = CPEs.size(); j != ee; ++j) {
1454  if (CPEs[j].RefCount == 0 && CPEs[j].CPEMI) {
1455  removeDeadCPEMI(CPEs[j].CPEMI);
1456  CPEs[j].CPEMI = nullptr;
1457  MadeChange = true;
1458  }
1459  }
1460  }
1461  return MadeChange;
1462 }
1463 
1464 /// isBBInRange - Returns true if the distance between specific MI and
1465 /// specific BB can fit in MI's displacement field.
1466 bool MipsConstantIslands::isBBInRange
1467  (MachineInstr *MI,MachineBasicBlock *DestBB, unsigned MaxDisp) {
1468  unsigned PCAdj = 4;
1469  unsigned BrOffset = getOffsetOf(MI) + PCAdj;
1470  unsigned DestOffset = BBInfo[DestBB->getNumber()].Offset;
1471 
1472  LLVM_DEBUG(dbgs() << "Branch of destination " << printMBBReference(*DestBB)
1473  << " from " << printMBBReference(*MI->getParent())
1474  << " max delta=" << MaxDisp << " from " << getOffsetOf(MI)
1475  << " to " << DestOffset << " offset "
1476  << int(DestOffset - BrOffset) << "\t" << *MI);
1477 
1478  if (BrOffset <= DestOffset) {
1479  // Branch before the Dest.
1480  if (DestOffset-BrOffset <= MaxDisp)
1481  return true;
1482  } else {
1483  if (BrOffset-DestOffset <= MaxDisp)
1484  return true;
1485  }
1486  return false;
1487 }
1488 
1489 /// fixupImmediateBr - Fix up an immediate branch whose destination is too far
1490 /// away to fit in its displacement field.
1491 bool MipsConstantIslands::fixupImmediateBr(ImmBranch &Br) {
1492  MachineInstr *MI = Br.MI;
1493  unsigned TargetOperand = branchTargetOperand(MI);
1494  MachineBasicBlock *DestBB = MI->getOperand(TargetOperand).getMBB();
1495 
1496  // Check to see if the DestBB is already in-range.
1497  if (isBBInRange(MI, DestBB, Br.MaxDisp))
1498  return false;
1499 
1500  if (!Br.isCond)
1501  return fixupUnconditionalBr(Br);
1502  return fixupConditionalBr(Br);
1503 }
1504 
1505 /// fixupUnconditionalBr - Fix up an unconditional branch whose destination is
1506 /// too far away to fit in its displacement field. If the LR register has been
1507 /// spilled in the epilogue, then we can use BL to implement a far jump.
1508 /// Otherwise, add an intermediate branch instruction to a branch.
1509 bool
1510 MipsConstantIslands::fixupUnconditionalBr(ImmBranch &Br) {
1511  MachineInstr *MI = Br.MI;
1512  MachineBasicBlock *MBB = MI->getParent();
1513  MachineBasicBlock *DestBB = MI->getOperand(0).getMBB();
1514  // Use BL to implement far jump.
1515  unsigned BimmX16MaxDisp = ((1 << 16)-1) * 2;
1516  if (isBBInRange(MI, DestBB, BimmX16MaxDisp)) {
1517  Br.MaxDisp = BimmX16MaxDisp;
1518  MI->setDesc(TII->get(Mips::BimmX16));
1519  }
1520  else {
1521  // need to give the math a more careful look here
1522  // this is really a segment address and not
1523  // a PC relative address. FIXME. But I think that
1524  // just reducing the bits by 1 as I've done is correct.
1525  // The basic block we are branching too much be longword aligned.
1526  // we know that RA is saved because we always save it right now.
1527  // this requirement will be relaxed later but we also have an alternate
1528  // way to implement this that I will implement that does not need jal.
1529  // We should have a way to back out this alignment restriction if we "can" later.
1530  // but it is not harmful.
1531  //
1532  DestBB->setAlignment(2);
1533  Br.MaxDisp = ((1<<24)-1) * 2;
1534  MI->setDesc(TII->get(Mips::JalB16));
1535  }
1536  BBInfo[MBB->getNumber()].Size += 2;
1537  adjustBBOffsetsAfter(MBB);
1538  HasFarJump = true;
1539  ++NumUBrFixed;
1540 
1541  LLVM_DEBUG(dbgs() << " Changed B to long jump " << *MI);
1542 
1543  return true;
1544 }
1545 
1546 /// fixupConditionalBr - Fix up a conditional branch whose destination is too
1547 /// far away to fit in its displacement field. It is converted to an inverse
1548 /// conditional branch + an unconditional branch to the destination.
1549 bool
1550 MipsConstantIslands::fixupConditionalBr(ImmBranch &Br) {
1551  MachineInstr *MI = Br.MI;
1552  unsigned TargetOperand = branchTargetOperand(MI);
1553  MachineBasicBlock *DestBB = MI->getOperand(TargetOperand).getMBB();
1554  unsigned Opcode = MI->getOpcode();
1555  unsigned LongFormOpcode = longformBranchOpcode(Opcode);
1556  unsigned LongFormMaxOff = branchMaxOffsets(LongFormOpcode);
1557 
1558  // Check to see if the DestBB is already in-range.
1559  if (isBBInRange(MI, DestBB, LongFormMaxOff)) {
1560  Br.MaxDisp = LongFormMaxOff;
1561  MI->setDesc(TII->get(LongFormOpcode));
1562  return true;
1563  }
1564 
1565  // Add an unconditional branch to the destination and invert the branch
1566  // condition to jump over it:
1567  // bteqz L1
1568  // =>
1569  // bnez L2
1570  // b L1
1571  // L2:
1572 
1573  // If the branch is at the end of its MBB and that has a fall-through block,
1574  // direct the updated conditional branch to the fall-through block. Otherwise,
1575  // split the MBB before the next instruction.
1576  MachineBasicBlock *MBB = MI->getParent();
1577  MachineInstr *BMI = &MBB->back();
1578  bool NeedSplit = (BMI != MI) || !BBHasFallthrough(MBB);
1579  unsigned OppositeBranchOpcode = TII->getOppositeBranchOpc(Opcode);
1580 
1581  ++NumCBrFixed;
1582  if (BMI != MI) {
1583  if (std::next(MachineBasicBlock::iterator(MI)) == std::prev(MBB->end()) &&
1584  BMI->isUnconditionalBranch()) {
1585  // Last MI in the BB is an unconditional branch. Can we simply invert the
1586  // condition and swap destinations:
1587  // beqz L1
1588  // b L2
1589  // =>
1590  // bnez L2
1591  // b L1
1592  unsigned BMITargetOperand = branchTargetOperand(BMI);
1593  MachineBasicBlock *NewDest =
1594  BMI->getOperand(BMITargetOperand).getMBB();
1595  if (isBBInRange(MI, NewDest, Br.MaxDisp)) {
1596  LLVM_DEBUG(
1597  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  LLVM_DEBUG(dbgs() << " Insert B to " << printMBBReference(*DestBB)
1619  << " also invert condition and change dest. to "
1620  << printMBBReference(*NextBB) << "\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  LLVM_DEBUG(dbgs() << "constant island constant " << *I << "\n");
1657  J = I->getNumOperands();
1658  LLVM_DEBUG(dbgs() << "num operands " << J << "\n");
1659  MachineOperand& Literal = I->getOperand(1);
1660  if (Literal.isImm()) {
1661  int64_t V = Literal.getImm();
1662  LLVM_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  LLVM_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 }
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:1288
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...
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 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:414
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:411
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:1213
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:1173
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:837
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:1229
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:643
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:681
unsigned succ_size() const
const MachineBasicBlock * getParent() const
Definition: MachineInstr.h:256
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:469
Representation of each machine instruction.
Definition: MachineInstr.h:64
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:731
IRTranslator LLVM IR MI
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:48
Register getReg() const
getReg - Returns the register number.
#define LLVM_DEBUG(X)
Definition: Debug.h:122
const MachineOperand & getOperand(unsigned i) const
Definition: MachineInstr.h:416
std::vector< MachineBasicBlock * >::iterator succ_iterator
Properties which a MachineFunction may have at a given point in time.
IntegerType * Int32Ty