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  unsigned postOffset() const { return Offset + Size; }
226  };
227 
228  std::vector<BasicBlockInfo> BBInfo;
229 
230  /// WaterList - A sorted list of basic blocks where islands could be placed
231  /// (i.e. blocks that don't fall through to the following block, due
232  /// to a return, unreachable, or unconditional branch).
233  std::vector<MachineBasicBlock*> WaterList;
234 
235  /// NewWaterList - The subset of WaterList that was created since the
236  /// previous iteration by inserting unconditional branches.
237  SmallSet<MachineBasicBlock*, 4> NewWaterList;
238 
239  using water_iterator = std::vector<MachineBasicBlock *>::iterator;
240 
241  /// CPUser - One user of a constant pool, keeping the machine instruction
242  /// pointer, the constant pool being referenced, and the max displacement
243  /// allowed from the instruction to the CP. The HighWaterMark records the
244  /// highest basic block where a new CPEntry can be placed. To ensure this
245  /// pass terminates, the CP entries are initially placed at the end of the
246  /// function and then move monotonically to lower addresses. The
247  /// exception to this rule is when the current CP entry for a particular
248  /// CPUser is out of range, but there is another CP entry for the same
249  /// constant value in range. We want to use the existing in-range CP
250  /// entry, but if it later moves out of range, the search for new water
251  /// should resume where it left off. The HighWaterMark is used to record
252  /// that point.
253  struct CPUser {
254  MachineInstr *MI;
255  MachineInstr *CPEMI;
256  MachineBasicBlock *HighWaterMark;
257 
258  private:
259  unsigned MaxDisp;
260  unsigned LongFormMaxDisp; // mips16 has 16/32 bit instructions
261  // with different displacements
262  unsigned LongFormOpcode;
263 
264  public:
265  bool NegOk;
266 
267  CPUser(MachineInstr *mi, MachineInstr *cpemi, unsigned maxdisp,
268  bool neg,
269  unsigned longformmaxdisp, unsigned longformopcode)
270  : MI(mi), CPEMI(cpemi), MaxDisp(maxdisp),
271  LongFormMaxDisp(longformmaxdisp), LongFormOpcode(longformopcode),
272  NegOk(neg){
273  HighWaterMark = CPEMI->getParent();
274  }
275 
276  /// getMaxDisp - Returns the maximum displacement supported by MI.
277  unsigned getMaxDisp() const {
278  unsigned xMaxDisp = ConstantIslandsSmallOffset?
280  return xMaxDisp;
281  }
282 
283  void setMaxDisp(unsigned val) {
284  MaxDisp = val;
285  }
286 
287  unsigned getLongFormMaxDisp() const {
288  return LongFormMaxDisp;
289  }
290 
291  unsigned getLongFormOpcode() const {
292  return LongFormOpcode;
293  }
294  };
295 
296  /// CPUsers - Keep track of all of the machine instructions that use various
297  /// constant pools and their max displacement.
298  std::vector<CPUser> CPUsers;
299 
300  /// CPEntry - One per constant pool entry, keeping the machine instruction
301  /// pointer, the constpool index, and the number of CPUser's which
302  /// reference this entry.
303  struct CPEntry {
304  MachineInstr *CPEMI;
305  unsigned CPI;
306  unsigned RefCount;
307 
308  CPEntry(MachineInstr *cpemi, unsigned cpi, unsigned rc = 0)
309  : CPEMI(cpemi), CPI(cpi), RefCount(rc) {}
310  };
311 
312  /// CPEntries - Keep track of all of the constant pool entry machine
313  /// instructions. For each original constpool index (i.e. those that
314  /// existed upon entry to this pass), it keeps a vector of entries.
315  /// Original elements are cloned as we go along; the clones are
316  /// put in the vector of the original element, but have distinct CPIs.
317  std::vector<std::vector<CPEntry>> CPEntries;
318 
319  /// ImmBranch - One per immediate branch, keeping the machine instruction
320  /// pointer, conditional or unconditional, the max displacement,
321  /// and (if isCond is true) the corresponding unconditional branch
322  /// opcode.
323  struct ImmBranch {
324  MachineInstr *MI;
325  unsigned MaxDisp : 31;
326  bool isCond : 1;
327  int UncondBr;
328 
329  ImmBranch(MachineInstr *mi, unsigned maxdisp, bool cond, int ubr)
330  : MI(mi), MaxDisp(maxdisp), isCond(cond), UncondBr(ubr) {}
331  };
332 
333  /// ImmBranches - Keep track of all the immediate branch instructions.
334  ///
335  std::vector<ImmBranch> ImmBranches;
336 
337  /// HasFarJump - True if any far jump instruction has been emitted during
338  /// the branch fix up pass.
339  bool HasFarJump;
340 
341  const MipsSubtarget *STI = nullptr;
342  const Mips16InstrInfo *TII;
343  MipsFunctionInfo *MFI;
344  MachineFunction *MF = nullptr;
345  MachineConstantPool *MCP = nullptr;
346 
347  unsigned PICLabelUId;
348  bool PrescannedForConstants = false;
349 
350  void initPICLabelUId(unsigned UId) {
351  PICLabelUId = UId;
352  }
353 
354  unsigned createPICLabelUId() {
355  return PICLabelUId++;
356  }
357 
358  public:
359  static char ID;
360 
361  MipsConstantIslands() : MachineFunctionPass(ID) {}
362 
363  StringRef getPassName() const override { return "Mips Constant Islands"; }
364 
365  bool runOnMachineFunction(MachineFunction &F) override;
366 
367  MachineFunctionProperties getRequiredProperties() const override {
370  }
371 
372  void doInitialPlacement(std::vector<MachineInstr*> &CPEMIs);
373  CPEntry *findConstPoolEntry(unsigned CPI, const MachineInstr *CPEMI);
374  llvm::Align getCPEAlign(const MachineInstr &CPEMI);
375  void initializeFunctionInfo(const std::vector<MachineInstr*> &CPEMIs);
376  unsigned getOffsetOf(MachineInstr *MI) const;
377  unsigned getUserOffset(CPUser&) const;
378  void dumpBBs();
379 
380  bool isOffsetInRange(unsigned UserOffset, unsigned TrialOffset,
381  unsigned Disp, bool NegativeOK);
382  bool isOffsetInRange(unsigned UserOffset, unsigned TrialOffset,
383  const CPUser &U);
384 
385  void computeBlockSize(MachineBasicBlock *MBB);
386  MachineBasicBlock *splitBlockBeforeInstr(MachineInstr &MI);
387  void updateForInsertedWaterBlock(MachineBasicBlock *NewBB);
388  void adjustBBOffsetsAfter(MachineBasicBlock *BB);
389  bool decrementCPEReferenceCount(unsigned CPI, MachineInstr* CPEMI);
390  int findInRangeCPEntry(CPUser& U, unsigned UserOffset);
391  int findLongFormInRangeCPEntry(CPUser& U, unsigned UserOffset);
392  bool findAvailableWater(CPUser&U, unsigned UserOffset,
393  water_iterator &WaterIter);
394  void createNewWater(unsigned CPUserIndex, unsigned UserOffset,
395  MachineBasicBlock *&NewMBB);
396  bool handleConstantPoolUser(unsigned CPUserIndex);
397  void removeDeadCPEMI(MachineInstr *CPEMI);
398  bool removeUnusedCPEntries();
399  bool isCPEntryInRange(MachineInstr *MI, unsigned UserOffset,
400  MachineInstr *CPEMI, unsigned Disp, bool NegOk,
401  bool DoDump = false);
402  bool isWaterInRange(unsigned UserOffset, MachineBasicBlock *Water,
403  CPUser &U, unsigned &Growth);
404  bool isBBInRange(MachineInstr *MI, MachineBasicBlock *BB, unsigned Disp);
405  bool fixupImmediateBr(ImmBranch &Br);
406  bool fixupConditionalBr(ImmBranch &Br);
407  bool fixupUnconditionalBr(ImmBranch &Br);
408 
409  void prescanForConstants();
410  };
411 
412 } // end anonymous namespace
413 
414 char MipsConstantIslands::ID = 0;
415 
416 bool MipsConstantIslands::isOffsetInRange
417  (unsigned UserOffset, unsigned TrialOffset,
418  const CPUser &U) {
419  return isOffsetInRange(UserOffset, TrialOffset,
420  U.getMaxDisp(), U.NegOk);
421 }
422 
423 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
424 /// print block size and offset information - debugging
425 LLVM_DUMP_METHOD void MipsConstantIslands::dumpBBs() {
426  for (unsigned J = 0, E = BBInfo.size(); J !=E; ++J) {
427  const BasicBlockInfo &BBI = BBInfo[J];
428  dbgs() << format("%08x %bb.%u\t", BBI.Offset, J)
429  << format(" size=%#x\n", BBInfo[J].Size);
430  }
431 }
432 #endif
433 
434 bool MipsConstantIslands::runOnMachineFunction(MachineFunction &mf) {
435  // The intention is for this to be a mips16 only pass for now
436  // FIXME:
437  MF = &mf;
438  MCP = mf.getConstantPool();
439  STI = &static_cast<const MipsSubtarget &>(mf.getSubtarget());
440  LLVM_DEBUG(dbgs() << "constant island machine function "
441  << "\n");
442  if (!STI->inMips16Mode() || !MipsSubtarget::useConstantIslands()) {
443  return false;
444  }
445  TII = (const Mips16InstrInfo *)STI->getInstrInfo();
446  MFI = MF->getInfo<MipsFunctionInfo>();
447  LLVM_DEBUG(dbgs() << "constant island processing "
448  << "\n");
449  //
450  // will need to make predermination if there is any constants we need to
451  // put in constant islands. TBD.
452  //
453  if (!PrescannedForConstants) prescanForConstants();
454 
455  HasFarJump = false;
456  // This pass invalidates liveness information when it splits basic blocks.
457  MF->getRegInfo().invalidateLiveness();
458 
459  // Renumber all of the machine basic blocks in the function, guaranteeing that
460  // the numbers agree with the position of the block in the function.
461  MF->RenumberBlocks();
462 
463  bool MadeChange = false;
464 
465  // Perform the initial placement of the constant pool entries. To start with,
466  // we put them all at the end of the function.
467  std::vector<MachineInstr*> CPEMIs;
468  if (!MCP->isEmpty())
469  doInitialPlacement(CPEMIs);
470 
471  /// The next UID to take is the first unused one.
472  initPICLabelUId(CPEMIs.size());
473 
474  // Do the initial scan of the function, building up information about the
475  // sizes of each block, the location of all the water, and finding all of the
476  // constant pool users.
477  initializeFunctionInfo(CPEMIs);
478  CPEMIs.clear();
479  LLVM_DEBUG(dumpBBs());
480 
481  /// Remove dead constant pool entries.
482  MadeChange |= removeUnusedCPEntries();
483 
484  // Iteratively place constant pool entries and fix up branches until there
485  // is no change.
486  unsigned NoCPIters = 0, NoBRIters = 0;
487  (void)NoBRIters;
488  while (true) {
489  LLVM_DEBUG(dbgs() << "Beginning CP iteration #" << NoCPIters << '\n');
490  bool CPChange = false;
491  for (unsigned i = 0, e = CPUsers.size(); i != e; ++i)
492  CPChange |= handleConstantPoolUser(i);
493  if (CPChange && ++NoCPIters > 30)
494  report_fatal_error("Constant Island pass failed to converge!");
495  LLVM_DEBUG(dumpBBs());
496 
497  // Clear NewWaterList now. If we split a block for branches, it should
498  // appear as "new water" for the next iteration of constant pool placement.
499  NewWaterList.clear();
500 
501  LLVM_DEBUG(dbgs() << "Beginning BR iteration #" << NoBRIters << '\n');
502  bool BRChange = false;
503  for (unsigned i = 0, e = ImmBranches.size(); i != e; ++i)
504  BRChange |= fixupImmediateBr(ImmBranches[i]);
505  if (BRChange && ++NoBRIters > 30)
506  report_fatal_error("Branch Fix Up pass failed to converge!");
507  LLVM_DEBUG(dumpBBs());
508  if (!CPChange && !BRChange)
509  break;
510  MadeChange = true;
511  }
512 
513  LLVM_DEBUG(dbgs() << '\n'; dumpBBs());
514 
515  BBInfo.clear();
516  WaterList.clear();
517  CPUsers.clear();
518  CPEntries.clear();
519  ImmBranches.clear();
520  return MadeChange;
521 }
522 
523 /// doInitialPlacement - Perform the initial placement of the constant pool
524 /// entries. To start with, we put them all at the end of the function.
525 void
526 MipsConstantIslands::doInitialPlacement(std::vector<MachineInstr*> &CPEMIs) {
527  // Create the basic block to hold the CPE's.
528  MachineBasicBlock *BB = MF->CreateMachineBasicBlock();
529  MF->push_back(BB);
530 
531  // MachineConstantPool measures alignment in bytes. We measure in log2(bytes).
532  const llvm::Align MaxAlign(MCP->getConstantPoolAlignment());
533 
534  // Mark the basic block as required by the const-pool.
535  // If AlignConstantIslands isn't set, use 4-byte alignment for everything.
536  BB->setAlignment(AlignConstantIslands ? MaxAlign : llvm::Align(4));
537 
538  // The function needs to be as aligned as the basic blocks. The linker may
539  // move functions around based on their alignment.
540  MF->ensureAlignment(BB->getAlignment());
541 
542  // Order the entries in BB by descending alignment. That ensures correct
543  // alignment of all entries as long as BB is sufficiently aligned. Keep
544  // track of the insertion point for each alignment. We are going to bucket
545  // sort the entries as they are created.
546  SmallVector<MachineBasicBlock::iterator, 8> InsPoint(Log2(MaxAlign) + 1,
547  BB->end());
548 
549  // Add all of the constants from the constant pool to the end block, use an
550  // identity mapping of CPI's to CPE's.
551  const std::vector<MachineConstantPoolEntry> &CPs = MCP->getConstants();
552 
553  const DataLayout &TD = MF->getDataLayout();
554  for (unsigned i = 0, e = CPs.size(); i != e; ++i) {
555  unsigned Size = TD.getTypeAllocSize(CPs[i].getType());
556  assert(Size >= 4 && "Too small constant pool entry");
557  unsigned Align = CPs[i].getAlignment();
558  assert(isPowerOf2_32(Align) && "Invalid alignment");
559  // Verify that all constant pool entries are a multiple of their alignment.
560  // If not, we would have to pad them out so that instructions stay aligned.
561  assert((Size % Align) == 0 && "CP Entry not multiple of 4 bytes!");
562 
563  // Insert CONSTPOOL_ENTRY before entries with a smaller alignment.
564  unsigned LogAlign = Log2_32(Align);
565  MachineBasicBlock::iterator InsAt = InsPoint[LogAlign];
566 
567  MachineInstr *CPEMI =
568  BuildMI(*BB, InsAt, DebugLoc(), TII->get(Mips::CONSTPOOL_ENTRY))
569  .addImm(i).addConstantPoolIndex(i).addImm(Size);
570 
571  CPEMIs.push_back(CPEMI);
572 
573  // Ensure that future entries with higher alignment get inserted before
574  // CPEMI. This is bucket sort with iterators.
575  for (unsigned a = LogAlign + 1; a <= Log2(MaxAlign); ++a)
576  if (InsPoint[a] == InsAt)
577  InsPoint[a] = CPEMI;
578  // Add a new CPEntry, but no corresponding CPUser yet.
579  CPEntries.emplace_back(1, CPEntry(CPEMI, i));
580  ++NumCPEs;
581  LLVM_DEBUG(dbgs() << "Moved CPI#" << i << " to end of function, size = "
582  << Size << ", align = " << Align << '\n');
583  }
584  LLVM_DEBUG(BB->dump());
585 }
586 
587 /// BBHasFallthrough - Return true if the specified basic block can fallthrough
588 /// into the block immediately after it.
590  // Get the next machine basic block in the function.
592  // Can't fall off end of function.
593  if (std::next(MBBI) == MBB->getParent()->end())
594  return false;
595 
596  MachineBasicBlock *NextBB = &*std::next(MBBI);
598  E = MBB->succ_end(); I != E; ++I)
599  if (*I == NextBB)
600  return true;
601 
602  return false;
603 }
604 
605 /// findConstPoolEntry - Given the constpool index and CONSTPOOL_ENTRY MI,
606 /// look up the corresponding CPEntry.
607 MipsConstantIslands::CPEntry
608 *MipsConstantIslands::findConstPoolEntry(unsigned CPI,
609  const MachineInstr *CPEMI) {
610  std::vector<CPEntry> &CPEs = CPEntries[CPI];
611  // Number of entries per constpool index should be small, just do a
612  // linear search.
613  for (unsigned i = 0, e = CPEs.size(); i != e; ++i) {
614  if (CPEs[i].CPEMI == CPEMI)
615  return &CPEs[i];
616  }
617  return nullptr;
618 }
619 
620 /// getCPEAlign - Returns the required alignment of the constant pool entry
621 /// represented by CPEMI. Alignment is measured in log2(bytes) units.
622 llvm::Align MipsConstantIslands::getCPEAlign(const MachineInstr &CPEMI) {
623  assert(CPEMI.getOpcode() == Mips::CONSTPOOL_ENTRY);
624 
625  // Everything is 4-byte aligned unless AlignConstantIslands is set.
627  return llvm::Align(4);
628 
629  unsigned CPI = CPEMI.getOperand(1).getIndex();
630  assert(CPI < MCP->getConstants().size() && "Invalid constant pool index.");
631  return llvm::Align(MCP->getConstants()[CPI].getAlignment());
632 }
633 
634 /// initializeFunctionInfo - Do the initial scan of the function, building up
635 /// information about the sizes of each block, the location of all the water,
636 /// and finding all of the constant pool users.
637 void MipsConstantIslands::
638 initializeFunctionInfo(const std::vector<MachineInstr*> &CPEMIs) {
639  BBInfo.clear();
640  BBInfo.resize(MF->getNumBlockIDs());
641 
642  // First thing, compute the size of all basic blocks, and see if the function
643  // has any inline assembly in it. If so, we have to be conservative about
644  // alignment assumptions, as we don't know for sure the size of any
645  // instructions in the inline assembly.
646  for (MachineFunction::iterator I = MF->begin(), E = MF->end(); I != E; ++I)
647  computeBlockSize(&*I);
648 
649  // Compute block offsets.
650  adjustBBOffsetsAfter(&MF->front());
651 
652  // Now go back through the instructions and build up our data structures.
653  for (MachineBasicBlock &MBB : *MF) {
654  // If this block doesn't fall through into the next MBB, then this is
655  // 'water' that a constant pool island could be placed.
656  if (!BBHasFallthrough(&MBB))
657  WaterList.push_back(&MBB);
658  for (MachineInstr &MI : MBB) {
659  if (MI.isDebugInstr())
660  continue;
661 
662  int Opc = MI.getOpcode();
663  if (MI.isBranch()) {
664  bool isCond = false;
665  unsigned Bits = 0;
666  unsigned Scale = 1;
667  int UOpc = Opc;
668  switch (Opc) {
669  default:
670  continue; // Ignore other branches for now
671  case Mips::Bimm16:
672  Bits = 11;
673  Scale = 2;
674  isCond = false;
675  break;
676  case Mips::BimmX16:
677  Bits = 16;
678  Scale = 2;
679  isCond = false;
680  break;
681  case Mips::BeqzRxImm16:
682  UOpc=Mips::Bimm16;
683  Bits = 8;
684  Scale = 2;
685  isCond = true;
686  break;
687  case Mips::BeqzRxImmX16:
688  UOpc=Mips::Bimm16;
689  Bits = 16;
690  Scale = 2;
691  isCond = true;
692  break;
693  case Mips::BnezRxImm16:
694  UOpc=Mips::Bimm16;
695  Bits = 8;
696  Scale = 2;
697  isCond = true;
698  break;
699  case Mips::BnezRxImmX16:
700  UOpc=Mips::Bimm16;
701  Bits = 16;
702  Scale = 2;
703  isCond = true;
704  break;
705  case Mips::Bteqz16:
706  UOpc=Mips::Bimm16;
707  Bits = 8;
708  Scale = 2;
709  isCond = true;
710  break;
711  case Mips::BteqzX16:
712  UOpc=Mips::Bimm16;
713  Bits = 16;
714  Scale = 2;
715  isCond = true;
716  break;
717  case Mips::Btnez16:
718  UOpc=Mips::Bimm16;
719  Bits = 8;
720  Scale = 2;
721  isCond = true;
722  break;
723  case Mips::BtnezX16:
724  UOpc=Mips::Bimm16;
725  Bits = 16;
726  Scale = 2;
727  isCond = true;
728  break;
729  }
730  // Record this immediate branch.
731  unsigned MaxOffs = ((1 << (Bits-1))-1) * Scale;
732  ImmBranches.push_back(ImmBranch(&MI, MaxOffs, isCond, UOpc));
733  }
734 
735  if (Opc == Mips::CONSTPOOL_ENTRY)
736  continue;
737 
738  // Scan the instructions for constant pool operands.
739  for (unsigned op = 0, e = MI.getNumOperands(); op != e; ++op)
740  if (MI.getOperand(op).isCPI()) {
741  // We found one. The addressing mode tells us the max displacement
742  // from the PC that this instruction permits.
743 
744  // Basic size info comes from the TSFlags field.
745  unsigned Bits = 0;
746  unsigned Scale = 1;
747  bool NegOk = false;
748  unsigned LongFormBits = 0;
749  unsigned LongFormScale = 0;
750  unsigned LongFormOpcode = 0;
751  switch (Opc) {
752  default:
753  llvm_unreachable("Unknown addressing mode for CP reference!");
754  case Mips::LwRxPcTcp16:
755  Bits = 8;
756  Scale = 4;
757  LongFormOpcode = Mips::LwRxPcTcpX16;
758  LongFormBits = 14;
759  LongFormScale = 1;
760  break;
761  case Mips::LwRxPcTcpX16:
762  Bits = 14;
763  Scale = 1;
764  NegOk = true;
765  break;
766  }
767  // Remember that this is a user of a CP entry.
768  unsigned CPI = MI.getOperand(op).getIndex();
769  MachineInstr *CPEMI = CPEMIs[CPI];
770  unsigned MaxOffs = ((1 << Bits)-1) * Scale;
771  unsigned LongFormMaxOffs = ((1 << LongFormBits)-1) * LongFormScale;
772  CPUsers.push_back(CPUser(&MI, CPEMI, MaxOffs, NegOk, LongFormMaxOffs,
773  LongFormOpcode));
774 
775  // Increment corresponding CPEntry reference count.
776  CPEntry *CPE = findConstPoolEntry(CPI, CPEMI);
777  assert(CPE && "Cannot find a corresponding CPEntry!");
778  CPE->RefCount++;
779 
780  // Instructions can only use one CP entry, don't bother scanning the
781  // rest of the operands.
782  break;
783  }
784  }
785  }
786 }
787 
788 /// computeBlockSize - Compute the size and some alignment information for MBB.
789 /// This function updates BBInfo directly.
790 void MipsConstantIslands::computeBlockSize(MachineBasicBlock *MBB) {
791  BasicBlockInfo &BBI = BBInfo[MBB->getNumber()];
792  BBI.Size = 0;
793 
794  for (const MachineInstr &MI : *MBB)
795  BBI.Size += TII->getInstSizeInBytes(MI);
796 }
797 
798 /// getOffsetOf - Return the current offset of the specified machine instruction
799 /// from the start of the function. This offset changes as stuff is moved
800 /// around inside the function.
801 unsigned MipsConstantIslands::getOffsetOf(MachineInstr *MI) const {
802  MachineBasicBlock *MBB = MI->getParent();
803 
804  // The offset is composed of two things: the sum of the sizes of all MBB's
805  // before this instruction's block, and the offset from the start of the block
806  // it is in.
807  unsigned Offset = BBInfo[MBB->getNumber()].Offset;
808 
809  // Sum instructions before MI in MBB.
810  for (MachineBasicBlock::iterator I = MBB->begin(); &*I != MI; ++I) {
811  assert(I != MBB->end() && "Didn't find MI in its own basic block?");
812  Offset += TII->getInstSizeInBytes(*I);
813  }
814  return Offset;
815 }
816 
817 /// CompareMBBNumbers - Little predicate function to sort the WaterList by MBB
818 /// ID.
819 static bool CompareMBBNumbers(const MachineBasicBlock *LHS,
820  const MachineBasicBlock *RHS) {
821  return LHS->getNumber() < RHS->getNumber();
822 }
823 
824 /// updateForInsertedWaterBlock - When a block is newly inserted into the
825 /// machine function, it upsets all of the block numbers. Renumber the blocks
826 /// and update the arrays that parallel this numbering.
827 void MipsConstantIslands::updateForInsertedWaterBlock
828  (MachineBasicBlock *NewBB) {
829  // Renumber the MBB's to keep them consecutive.
830  NewBB->getParent()->RenumberBlocks(NewBB);
831 
832  // Insert an entry into BBInfo to align it properly with the (newly
833  // renumbered) block numbers.
834  BBInfo.insert(BBInfo.begin() + NewBB->getNumber(), BasicBlockInfo());
835 
836  // Next, update WaterList. Specifically, we need to add NewMBB as having
837  // available water after it.
838  water_iterator IP = llvm::lower_bound(WaterList, NewBB, CompareMBBNumbers);
839  WaterList.insert(IP, NewBB);
840 }
841 
842 unsigned MipsConstantIslands::getUserOffset(CPUser &U) const {
843  return getOffsetOf(U.MI);
844 }
845 
846 /// Split the basic block containing MI into two blocks, which are joined by
847 /// an unconditional branch. Update data structures and renumber blocks to
848 /// account for this change and returns the newly created block.
850 MipsConstantIslands::splitBlockBeforeInstr(MachineInstr &MI) {
851  MachineBasicBlock *OrigBB = MI.getParent();
852 
853  // Create a new MBB for the code after the OrigBB.
854  MachineBasicBlock *NewBB =
855  MF->CreateMachineBasicBlock(OrigBB->getBasicBlock());
856  MachineFunction::iterator MBBI = ++OrigBB->getIterator();
857  MF->insert(MBBI, NewBB);
858 
859  // Splice the instructions starting with MI over to NewBB.
860  NewBB->splice(NewBB->end(), OrigBB, MI, OrigBB->end());
861 
862  // Add an unconditional branch from OrigBB to NewBB.
863  // Note the new unconditional branch is not being recorded.
864  // There doesn't seem to be meaningful DebugInfo available; this doesn't
865  // correspond to anything in the source.
866  BuildMI(OrigBB, DebugLoc(), TII->get(Mips::Bimm16)).addMBB(NewBB);
867  ++NumSplit;
868 
869  // Update the CFG. All succs of OrigBB are now succs of NewBB.
870  NewBB->transferSuccessors(OrigBB);
871 
872  // OrigBB branches to NewBB.
873  OrigBB->addSuccessor(NewBB);
874 
875  // Update internal data structures to account for the newly inserted MBB.
876  // This is almost the same as updateForInsertedWaterBlock, except that
877  // the Water goes after OrigBB, not NewBB.
878  MF->RenumberBlocks(NewBB);
879 
880  // Insert an entry into BBInfo to align it properly with the (newly
881  // renumbered) block numbers.
882  BBInfo.insert(BBInfo.begin() + NewBB->getNumber(), BasicBlockInfo());
883 
884  // Next, update WaterList. Specifically, we need to add OrigMBB as having
885  // available water after it (but not if it's already there, which happens
886  // when splitting before a conditional branch that is followed by an
887  // unconditional branch - in that case we want to insert NewBB).
888  water_iterator IP = llvm::lower_bound(WaterList, OrigBB, CompareMBBNumbers);
889  MachineBasicBlock* WaterBB = *IP;
890  if (WaterBB == OrigBB)
891  WaterList.insert(std::next(IP), NewBB);
892  else
893  WaterList.insert(IP, OrigBB);
894  NewWaterList.insert(OrigBB);
895 
896  // Figure out how large the OrigBB is. As the first half of the original
897  // block, it cannot contain a tablejump. The size includes
898  // the new jump we added. (It should be possible to do this without
899  // recounting everything, but it's very confusing, and this is rarely
900  // executed.)
901  computeBlockSize(OrigBB);
902 
903  // Figure out how large the NewMBB is. As the second half of the original
904  // block, it may contain a tablejump.
905  computeBlockSize(NewBB);
906 
907  // All BBOffsets following these blocks must be modified.
908  adjustBBOffsetsAfter(OrigBB);
909 
910  return NewBB;
911 }
912 
913 /// isOffsetInRange - Checks whether UserOffset (the location of a constant pool
914 /// reference) is within MaxDisp of TrialOffset (a proposed location of a
915 /// constant pool entry).
916 bool MipsConstantIslands::isOffsetInRange(unsigned UserOffset,
917  unsigned TrialOffset, unsigned MaxDisp,
918  bool NegativeOK) {
919  if (UserOffset <= TrialOffset) {
920  // User before the Trial.
921  if (TrialOffset - UserOffset <= MaxDisp)
922  return true;
923  } else if (NegativeOK) {
924  if (UserOffset - TrialOffset <= MaxDisp)
925  return true;
926  }
927  return false;
928 }
929 
930 /// isWaterInRange - Returns true if a CPE placed after the specified
931 /// Water (a basic block) will be in range for the specific MI.
932 ///
933 /// Compute how much the function will grow by inserting a CPE after Water.
934 bool MipsConstantIslands::isWaterInRange(unsigned UserOffset,
935  MachineBasicBlock* Water, CPUser &U,
936  unsigned &Growth) {
937  unsigned CPEOffset = BBInfo[Water->getNumber()].postOffset();
938  unsigned NextBlockOffset;
939  llvm::Align NextBlockAlignment;
940  MachineFunction::const_iterator NextBlock = ++Water->getIterator();
941  if (NextBlock == MF->end()) {
942  NextBlockOffset = BBInfo[Water->getNumber()].postOffset();
943  NextBlockAlignment = llvm::Align::None();
944  } else {
945  NextBlockOffset = BBInfo[NextBlock->getNumber()].Offset;
946  NextBlockAlignment = NextBlock->getAlignment();
947  }
948  unsigned Size = U.CPEMI->getOperand(2).getImm();
949  unsigned CPEEnd = CPEOffset + Size;
950 
951  // The CPE may be able to hide in the alignment padding before the next
952  // block. It may also cause more padding to be required if it is more aligned
953  // that the next block.
954  if (CPEEnd > NextBlockOffset) {
955  Growth = CPEEnd - NextBlockOffset;
956  // Compute the padding that would go at the end of the CPE to align the next
957  // block.
958  Growth += offsetToAlignment(CPEEnd, NextBlockAlignment);
959 
960  // If the CPE is to be inserted before the instruction, that will raise
961  // the offset of the instruction. Also account for unknown alignment padding
962  // in blocks between CPE and the user.
963  if (CPEOffset < UserOffset)
964  UserOffset += Growth;
965  } else
966  // CPE fits in existing padding.
967  Growth = 0;
968 
969  return isOffsetInRange(UserOffset, CPEOffset, U);
970 }
971 
972 /// isCPEntryInRange - Returns true if the distance between specific MI and
973 /// specific ConstPool entry instruction can fit in MI's displacement field.
974 bool MipsConstantIslands::isCPEntryInRange
975  (MachineInstr *MI, unsigned UserOffset,
976  MachineInstr *CPEMI, unsigned MaxDisp,
977  bool NegOk, bool DoDump) {
978  unsigned CPEOffset = getOffsetOf(CPEMI);
979 
980  if (DoDump) {
981  LLVM_DEBUG({
982  unsigned Block = MI->getParent()->getNumber();
983  const BasicBlockInfo &BBI = BBInfo[Block];
984  dbgs() << "User of CPE#" << CPEMI->getOperand(0).getImm()
985  << " max delta=" << MaxDisp
986  << format(" insn address=%#x", UserOffset) << " in "
987  << printMBBReference(*MI->getParent()) << ": "
988  << format("%#x-%x\t", BBI.Offset, BBI.postOffset()) << *MI
989  << format("CPE address=%#x offset=%+d: ", CPEOffset,
990  int(CPEOffset - UserOffset));
991  });
992  }
993 
994  return isOffsetInRange(UserOffset, CPEOffset, MaxDisp, NegOk);
995 }
996 
997 #ifndef NDEBUG
998 /// BBIsJumpedOver - Return true of the specified basic block's only predecessor
999 /// unconditionally branches to its only successor.
1001  if (MBB->pred_size() != 1 || MBB->succ_size() != 1)
1002  return false;
1003  MachineBasicBlock *Succ = *MBB->succ_begin();
1004  MachineBasicBlock *Pred = *MBB->pred_begin();
1005  MachineInstr *PredMI = &Pred->back();
1006  if (PredMI->getOpcode() == Mips::Bimm16)
1007  return PredMI->getOperand(0).getMBB() == Succ;
1008  return false;
1009 }
1010 #endif
1011 
1012 void MipsConstantIslands::adjustBBOffsetsAfter(MachineBasicBlock *BB) {
1013  unsigned BBNum = BB->getNumber();
1014  for(unsigned i = BBNum + 1, e = MF->getNumBlockIDs(); i < e; ++i) {
1015  // Get the offset and known bits at the end of the layout predecessor.
1016  // Include the alignment of the current block.
1017  unsigned Offset = BBInfo[i - 1].Offset + BBInfo[i - 1].Size;
1018  BBInfo[i].Offset = Offset;
1019  }
1020 }
1021 
1022 /// decrementCPEReferenceCount - find the constant pool entry with index CPI
1023 /// and instruction CPEMI, and decrement its refcount. If the refcount
1024 /// becomes 0 remove the entry and instruction. Returns true if we removed
1025 /// the entry, false if we didn't.
1026 bool MipsConstantIslands::decrementCPEReferenceCount(unsigned CPI,
1027  MachineInstr *CPEMI) {
1028  // Find the old entry. Eliminate it if it is no longer used.
1029  CPEntry *CPE = findConstPoolEntry(CPI, CPEMI);
1030  assert(CPE && "Unexpected!");
1031  if (--CPE->RefCount == 0) {
1032  removeDeadCPEMI(CPEMI);
1033  CPE->CPEMI = nullptr;
1034  --NumCPEs;
1035  return true;
1036  }
1037  return false;
1038 }
1039 
1040 /// LookForCPEntryInRange - see if the currently referenced CPE is in range;
1041 /// if not, see if an in-range clone of the CPE is in range, and if so,
1042 /// change the data structures so the user references the clone. Returns:
1043 /// 0 = no existing entry found
1044 /// 1 = entry found, and there were no code insertions or deletions
1045 /// 2 = entry found, and there were code insertions or deletions
1046 int MipsConstantIslands::findInRangeCPEntry(CPUser& U, unsigned UserOffset)
1047 {
1048  MachineInstr *UserMI = U.MI;
1049  MachineInstr *CPEMI = U.CPEMI;
1050 
1051  // Check to see if the CPE is already in-range.
1052  if (isCPEntryInRange(UserMI, UserOffset, CPEMI, U.getMaxDisp(), U.NegOk,
1053  true)) {
1054  LLVM_DEBUG(dbgs() << "In range\n");
1055  return 1;
1056  }
1057 
1058  // No. Look for previously created clones of the CPE that are in range.
1059  unsigned CPI = CPEMI->getOperand(1).getIndex();
1060  std::vector<CPEntry> &CPEs = CPEntries[CPI];
1061  for (unsigned i = 0, e = CPEs.size(); i != e; ++i) {
1062  // We already tried this one
1063  if (CPEs[i].CPEMI == CPEMI)
1064  continue;
1065  // Removing CPEs can leave empty entries, skip
1066  if (CPEs[i].CPEMI == nullptr)
1067  continue;
1068  if (isCPEntryInRange(UserMI, UserOffset, CPEs[i].CPEMI, U.getMaxDisp(),
1069  U.NegOk)) {
1070  LLVM_DEBUG(dbgs() << "Replacing CPE#" << CPI << " with CPE#"
1071  << CPEs[i].CPI << "\n");
1072  // Point the CPUser node to the replacement
1073  U.CPEMI = CPEs[i].CPEMI;
1074  // Change the CPI in the instruction operand to refer to the clone.
1075  for (unsigned j = 0, e = UserMI->getNumOperands(); j != e; ++j)
1076  if (UserMI->getOperand(j).isCPI()) {
1077  UserMI->getOperand(j).setIndex(CPEs[i].CPI);
1078  break;
1079  }
1080  // Adjust the refcount of the clone...
1081  CPEs[i].RefCount++;
1082  // ...and the original. If we didn't remove the old entry, none of the
1083  // addresses changed, so we don't need another pass.
1084  return decrementCPEReferenceCount(CPI, CPEMI) ? 2 : 1;
1085  }
1086  }
1087  return 0;
1088 }
1089 
1090 /// LookForCPEntryInRange - see if the currently referenced CPE is in range;
1091 /// This version checks if the longer form of the instruction can be used to
1092 /// to satisfy things.
1093 /// if not, see if an in-range clone of the CPE is in range, and if so,
1094 /// change the data structures so the user references the clone. Returns:
1095 /// 0 = no existing entry found
1096 /// 1 = entry found, and there were no code insertions or deletions
1097 /// 2 = entry found, and there were code insertions or deletions
1098 int MipsConstantIslands::findLongFormInRangeCPEntry
1099  (CPUser& U, unsigned UserOffset)
1100 {
1101  MachineInstr *UserMI = U.MI;
1102  MachineInstr *CPEMI = U.CPEMI;
1103 
1104  // Check to see if the CPE is already in-range.
1105  if (isCPEntryInRange(UserMI, UserOffset, CPEMI,
1106  U.getLongFormMaxDisp(), U.NegOk,
1107  true)) {
1108  LLVM_DEBUG(dbgs() << "In range\n");
1109  UserMI->setDesc(TII->get(U.getLongFormOpcode()));
1110  U.setMaxDisp(U.getLongFormMaxDisp());
1111  return 2; // instruction is longer length now
1112  }
1113 
1114  // No. Look for previously created clones of the CPE that are in range.
1115  unsigned CPI = CPEMI->getOperand(1).getIndex();
1116  std::vector<CPEntry> &CPEs = CPEntries[CPI];
1117  for (unsigned i = 0, e = CPEs.size(); i != e; ++i) {
1118  // We already tried this one
1119  if (CPEs[i].CPEMI == CPEMI)
1120  continue;
1121  // Removing CPEs can leave empty entries, skip
1122  if (CPEs[i].CPEMI == nullptr)
1123  continue;
1124  if (isCPEntryInRange(UserMI, UserOffset, CPEs[i].CPEMI,
1125  U.getLongFormMaxDisp(), U.NegOk)) {
1126  LLVM_DEBUG(dbgs() << "Replacing CPE#" << CPI << " with CPE#"
1127  << CPEs[i].CPI << "\n");
1128  // Point the CPUser node to the replacement
1129  U.CPEMI = CPEs[i].CPEMI;
1130  // Change the CPI in the instruction operand to refer to the clone.
1131  for (unsigned j = 0, e = UserMI->getNumOperands(); j != e; ++j)
1132  if (UserMI->getOperand(j).isCPI()) {
1133  UserMI->getOperand(j).setIndex(CPEs[i].CPI);
1134  break;
1135  }
1136  // Adjust the refcount of the clone...
1137  CPEs[i].RefCount++;
1138  // ...and the original. If we didn't remove the old entry, none of the
1139  // addresses changed, so we don't need another pass.
1140  return decrementCPEReferenceCount(CPI, CPEMI) ? 2 : 1;
1141  }
1142  }
1143  return 0;
1144 }
1145 
1146 /// getUnconditionalBrDisp - Returns the maximum displacement that can fit in
1147 /// the specific unconditional branch instruction.
1148 static inline unsigned getUnconditionalBrDisp(int Opc) {
1149  switch (Opc) {
1150  case Mips::Bimm16:
1151  return ((1<<10)-1)*2;
1152  case Mips::BimmX16:
1153  return ((1<<16)-1)*2;
1154  default:
1155  break;
1156  }
1157  return ((1<<16)-1)*2;
1158 }
1159 
1160 /// findAvailableWater - Look for an existing entry in the WaterList in which
1161 /// we can place the CPE referenced from U so it's within range of U's MI.
1162 /// Returns true if found, false if not. If it returns true, WaterIter
1163 /// is set to the WaterList entry.
1164 /// To ensure that this pass
1165 /// terminates, the CPE location for a particular CPUser is only allowed to
1166 /// move to a lower address, so search backward from the end of the list and
1167 /// prefer the first water that is in range.
1168 bool MipsConstantIslands::findAvailableWater(CPUser &U, unsigned UserOffset,
1169  water_iterator &WaterIter) {
1170  if (WaterList.empty())
1171  return false;
1172 
1173  unsigned BestGrowth = ~0u;
1174  for (water_iterator IP = std::prev(WaterList.end()), B = WaterList.begin();;
1175  --IP) {
1176  MachineBasicBlock* WaterBB = *IP;
1177  // Check if water is in range and is either at a lower address than the
1178  // current "high water mark" or a new water block that was created since
1179  // the previous iteration by inserting an unconditional branch. In the
1180  // latter case, we want to allow resetting the high water mark back to
1181  // this new water since we haven't seen it before. Inserting branches
1182  // should be relatively uncommon and when it does happen, we want to be
1183  // sure to take advantage of it for all the CPEs near that block, so that
1184  // we don't insert more branches than necessary.
1185  unsigned Growth;
1186  if (isWaterInRange(UserOffset, WaterBB, U, Growth) &&
1187  (WaterBB->getNumber() < U.HighWaterMark->getNumber() ||
1188  NewWaterList.count(WaterBB)) && Growth < BestGrowth) {
1189  // This is the least amount of required padding seen so far.
1190  BestGrowth = Growth;
1191  WaterIter = IP;
1192  LLVM_DEBUG(dbgs() << "Found water after " << printMBBReference(*WaterBB)
1193  << " Growth=" << Growth << '\n');
1194 
1195  // Keep looking unless it is perfect.
1196  if (BestGrowth == 0)
1197  return true;
1198  }
1199  if (IP == B)
1200  break;
1201  }
1202  return BestGrowth != ~0u;
1203 }
1204 
1205 /// createNewWater - No existing WaterList entry will work for
1206 /// CPUsers[CPUserIndex], so create a place to put the CPE. The end of the
1207 /// block is used if in range, and the conditional branch munged so control
1208 /// flow is correct. Otherwise the block is split to create a hole with an
1209 /// unconditional branch around it. In either case NewMBB is set to a
1210 /// block following which the new island can be inserted (the WaterList
1211 /// is not adjusted).
1212 void MipsConstantIslands::createNewWater(unsigned CPUserIndex,
1213  unsigned UserOffset,
1214  MachineBasicBlock *&NewMBB) {
1215  CPUser &U = CPUsers[CPUserIndex];
1216  MachineInstr *UserMI = U.MI;
1217  MachineInstr *CPEMI = U.CPEMI;
1218  MachineBasicBlock *UserMBB = UserMI->getParent();
1219  const BasicBlockInfo &UserBBI = BBInfo[UserMBB->getNumber()];
1220 
1221  // If the block does not end in an unconditional branch already, and if the
1222  // end of the block is within range, make new water there.
1223  if (BBHasFallthrough(UserMBB)) {
1224  // Size of branch to insert.
1225  unsigned Delta = 2;
1226  // Compute the offset where the CPE will begin.
1227  unsigned CPEOffset = UserBBI.postOffset() + Delta;
1228 
1229  if (isOffsetInRange(UserOffset, CPEOffset, U)) {
1230  LLVM_DEBUG(dbgs() << "Split at end of " << printMBBReference(*UserMBB)
1231  << format(", expected CPE offset %#x\n", CPEOffset));
1232  NewMBB = &*++UserMBB->getIterator();
1233  // Add an unconditional branch from UserMBB to fallthrough block. Record
1234  // it for branch lengthening; this new branch will not get out of range,
1235  // but if the preceding conditional branch is out of range, the targets
1236  // will be exchanged, and the altered branch may be out of range, so the
1237  // machinery has to know about it.
1238  int UncondBr = Mips::Bimm16;
1239  BuildMI(UserMBB, DebugLoc(), TII->get(UncondBr)).addMBB(NewMBB);
1240  unsigned MaxDisp = getUnconditionalBrDisp(UncondBr);
1241  ImmBranches.push_back(ImmBranch(&UserMBB->back(),
1242  MaxDisp, false, UncondBr));
1243  BBInfo[UserMBB->getNumber()].Size += Delta;
1244  adjustBBOffsetsAfter(UserMBB);
1245  return;
1246  }
1247  }
1248 
1249  // What a big block. Find a place within the block to split it.
1250 
1251  // Try to split the block so it's fully aligned. Compute the latest split
1252  // point where we can add a 4-byte branch instruction, and then align to
1253  // Align which is the largest possible alignment in the function.
1254  const llvm::Align Align = MF->getAlignment();
1255  unsigned BaseInsertOffset = UserOffset + U.getMaxDisp();
1256  LLVM_DEBUG(dbgs() << format("Split in middle of big block before %#x",
1257  BaseInsertOffset));
1258 
1259  // The 4 in the following is for the unconditional branch we'll be inserting
1260  // Alignment of the island is handled
1261  // inside isOffsetInRange.
1262  BaseInsertOffset -= 4;
1263 
1264  LLVM_DEBUG(dbgs() << format(", adjusted to %#x", BaseInsertOffset)
1265  << " la=" << Log2(Align) << '\n');
1266 
1267  // This could point off the end of the block if we've already got constant
1268  // pool entries following this block; only the last one is in the water list.
1269  // Back past any possible branches (allow for a conditional and a maximally
1270  // long unconditional).
1271  if (BaseInsertOffset + 8 >= UserBBI.postOffset()) {
1272  BaseInsertOffset = UserBBI.postOffset() - 8;
1273  LLVM_DEBUG(dbgs() << format("Move inside block: %#x\n", BaseInsertOffset));
1274  }
1275  unsigned EndInsertOffset = BaseInsertOffset + 4 +
1276  CPEMI->getOperand(2).getImm();
1277  MachineBasicBlock::iterator MI = UserMI;
1278  ++MI;
1279  unsigned CPUIndex = CPUserIndex+1;
1280  unsigned NumCPUsers = CPUsers.size();
1281  //MachineInstr *LastIT = 0;
1282  for (unsigned Offset = UserOffset + TII->getInstSizeInBytes(*UserMI);
1283  Offset < BaseInsertOffset;
1284  Offset += TII->getInstSizeInBytes(*MI), MI = std::next(MI)) {
1285  assert(MI != UserMBB->end() && "Fell off end of block");
1286  if (CPUIndex < NumCPUsers && CPUsers[CPUIndex].MI == MI) {
1287  CPUser &U = CPUsers[CPUIndex];
1288  if (!isOffsetInRange(Offset, EndInsertOffset, U)) {
1289  // Shift intertion point by one unit of alignment so it is within reach.
1290  BaseInsertOffset -= Align.value();
1291  EndInsertOffset -= Align.value();
1292  }
1293  // This is overly conservative, as we don't account for CPEMIs being
1294  // reused within the block, but it doesn't matter much. Also assume CPEs
1295  // are added in order with alignment padding. We may eventually be able
1296  // to pack the aligned CPEs better.
1297  EndInsertOffset += U.CPEMI->getOperand(2).getImm();
1298  CPUIndex++;
1299  }
1300  }
1301 
1302  NewMBB = splitBlockBeforeInstr(*--MI);
1303 }
1304 
1305 /// handleConstantPoolUser - Analyze the specified user, checking to see if it
1306 /// is out-of-range. If so, pick up the constant pool value and move it some
1307 /// place in-range. Return true if we changed any addresses (thus must run
1308 /// another pass of branch lengthening), false otherwise.
1309 bool MipsConstantIslands::handleConstantPoolUser(unsigned CPUserIndex) {
1310  CPUser &U = CPUsers[CPUserIndex];
1311  MachineInstr *UserMI = U.MI;
1312  MachineInstr *CPEMI = U.CPEMI;
1313  unsigned CPI = CPEMI->getOperand(1).getIndex();
1314  unsigned Size = CPEMI->getOperand(2).getImm();
1315  // Compute this only once, it's expensive.
1316  unsigned UserOffset = getUserOffset(U);
1317 
1318  // See if the current entry is within range, or there is a clone of it
1319  // in range.
1320  int result = findInRangeCPEntry(U, UserOffset);
1321  if (result==1) return false;
1322  else if (result==2) return true;
1323 
1324  // Look for water where we can place this CPE.
1325  MachineBasicBlock *NewIsland = MF->CreateMachineBasicBlock();
1326  MachineBasicBlock *NewMBB;
1327  water_iterator IP;
1328  if (findAvailableWater(U, UserOffset, IP)) {
1329  LLVM_DEBUG(dbgs() << "Found water in range\n");
1330  MachineBasicBlock *WaterBB = *IP;
1331 
1332  // If the original WaterList entry was "new water" on this iteration,
1333  // propagate that to the new island. This is just keeping NewWaterList
1334  // updated to match the WaterList, which will be updated below.
1335  if (NewWaterList.erase(WaterBB))
1336  NewWaterList.insert(NewIsland);
1337 
1338  // The new CPE goes before the following block (NewMBB).
1339  NewMBB = &*++WaterBB->getIterator();
1340  } else {
1341  // No water found.
1342  // we first see if a longer form of the instrucion could have reached
1343  // the constant. in that case we won't bother to split
1344  if (!NoLoadRelaxation) {
1345  result = findLongFormInRangeCPEntry(U, UserOffset);
1346  if (result != 0) return true;
1347  }
1348  LLVM_DEBUG(dbgs() << "No water found\n");
1349  createNewWater(CPUserIndex, UserOffset, NewMBB);
1350 
1351  // splitBlockBeforeInstr adds to WaterList, which is important when it is
1352  // called while handling branches so that the water will be seen on the
1353  // next iteration for constant pools, but in this context, we don't want
1354  // it. Check for this so it will be removed from the WaterList.
1355  // Also remove any entry from NewWaterList.
1356  MachineBasicBlock *WaterBB = &*--NewMBB->getIterator();
1357  IP = llvm::find(WaterList, WaterBB);
1358  if (IP != WaterList.end())
1359  NewWaterList.erase(WaterBB);
1360 
1361  // We are adding new water. Update NewWaterList.
1362  NewWaterList.insert(NewIsland);
1363  }
1364 
1365  // Remove the original WaterList entry; we want subsequent insertions in
1366  // this vicinity to go after the one we're about to insert. This
1367  // considerably reduces the number of times we have to move the same CPE
1368  // more than once and is also important to ensure the algorithm terminates.
1369  if (IP != WaterList.end())
1370  WaterList.erase(IP);
1371 
1372  // Okay, we know we can put an island before NewMBB now, do it!
1373  MF->insert(NewMBB->getIterator(), NewIsland);
1374 
1375  // Update internal data structures to account for the newly inserted MBB.
1376  updateForInsertedWaterBlock(NewIsland);
1377 
1378  // Decrement the old entry, and remove it if refcount becomes 0.
1379  decrementCPEReferenceCount(CPI, CPEMI);
1380 
1381  // No existing clone of this CPE is within range.
1382  // We will be generating a new clone. Get a UID for it.
1383  unsigned ID = createPICLabelUId();
1384 
1385  // Now that we have an island to add the CPE to, clone the original CPE and
1386  // add it to the island.
1387  U.HighWaterMark = NewIsland;
1388  U.CPEMI = BuildMI(NewIsland, DebugLoc(), TII->get(Mips::CONSTPOOL_ENTRY))
1389  .addImm(ID).addConstantPoolIndex(CPI).addImm(Size);
1390  CPEntries[CPI].push_back(CPEntry(U.CPEMI, ID, 1));
1391  ++NumCPEs;
1392 
1393  // Mark the basic block as aligned as required by the const-pool entry.
1394  NewIsland->setAlignment(getCPEAlign(*U.CPEMI));
1395 
1396  // Increase the size of the island block to account for the new entry.
1397  BBInfo[NewIsland->getNumber()].Size += Size;
1398  adjustBBOffsetsAfter(&*--NewIsland->getIterator());
1399 
1400  // Finally, change the CPI in the instruction operand to be ID.
1401  for (unsigned i = 0, e = UserMI->getNumOperands(); i != e; ++i)
1402  if (UserMI->getOperand(i).isCPI()) {
1403  UserMI->getOperand(i).setIndex(ID);
1404  break;
1405  }
1406 
1407  LLVM_DEBUG(
1408  dbgs() << " Moved CPE to #" << ID << " CPI=" << CPI
1409  << format(" offset=%#x\n", BBInfo[NewIsland->getNumber()].Offset));
1410 
1411  return true;
1412 }
1413 
1414 /// removeDeadCPEMI - Remove a dead constant pool entry instruction. Update
1415 /// sizes and offsets of impacted basic blocks.
1416 void MipsConstantIslands::removeDeadCPEMI(MachineInstr *CPEMI) {
1417  MachineBasicBlock *CPEBB = CPEMI->getParent();
1418  unsigned Size = CPEMI->getOperand(2).getImm();
1419  CPEMI->eraseFromParent();
1420  BBInfo[CPEBB->getNumber()].Size -= Size;
1421  // All succeeding offsets have the current size value added in, fix this.
1422  if (CPEBB->empty()) {
1423  BBInfo[CPEBB->getNumber()].Size = 0;
1424 
1425  // This block no longer needs to be aligned.
1426  CPEBB->setAlignment(llvm::Align(1));
1427  } else {
1428  // Entries are sorted by descending alignment, so realign from the front.
1429  CPEBB->setAlignment(getCPEAlign(*CPEBB->begin()));
1430  }
1431 
1432  adjustBBOffsetsAfter(CPEBB);
1433  // An island has only one predecessor BB and one successor BB. Check if
1434  // this BB's predecessor jumps directly to this BB's successor. This
1435  // shouldn't happen currently.
1436  assert(!BBIsJumpedOver(CPEBB) && "How did this happen?");
1437  // FIXME: remove the empty blocks after all the work is done?
1438 }
1439 
1440 /// removeUnusedCPEntries - Remove constant pool entries whose refcounts
1441 /// are zero.
1442 bool MipsConstantIslands::removeUnusedCPEntries() {
1443  unsigned MadeChange = false;
1444  for (unsigned i = 0, e = CPEntries.size(); i != e; ++i) {
1445  std::vector<CPEntry> &CPEs = CPEntries[i];
1446  for (unsigned j = 0, ee = CPEs.size(); j != ee; ++j) {
1447  if (CPEs[j].RefCount == 0 && CPEs[j].CPEMI) {
1448  removeDeadCPEMI(CPEs[j].CPEMI);
1449  CPEs[j].CPEMI = nullptr;
1450  MadeChange = true;
1451  }
1452  }
1453  }
1454  return MadeChange;
1455 }
1456 
1457 /// isBBInRange - Returns true if the distance between specific MI and
1458 /// specific BB can fit in MI's displacement field.
1459 bool MipsConstantIslands::isBBInRange
1460  (MachineInstr *MI,MachineBasicBlock *DestBB, unsigned MaxDisp) {
1461  unsigned PCAdj = 4;
1462  unsigned BrOffset = getOffsetOf(MI) + PCAdj;
1463  unsigned DestOffset = BBInfo[DestBB->getNumber()].Offset;
1464 
1465  LLVM_DEBUG(dbgs() << "Branch of destination " << printMBBReference(*DestBB)
1466  << " from " << printMBBReference(*MI->getParent())
1467  << " max delta=" << MaxDisp << " from " << getOffsetOf(MI)
1468  << " to " << DestOffset << " offset "
1469  << int(DestOffset - BrOffset) << "\t" << *MI);
1470 
1471  if (BrOffset <= DestOffset) {
1472  // Branch before the Dest.
1473  if (DestOffset-BrOffset <= MaxDisp)
1474  return true;
1475  } else {
1476  if (BrOffset-DestOffset <= MaxDisp)
1477  return true;
1478  }
1479  return false;
1480 }
1481 
1482 /// fixupImmediateBr - Fix up an immediate branch whose destination is too far
1483 /// away to fit in its displacement field.
1484 bool MipsConstantIslands::fixupImmediateBr(ImmBranch &Br) {
1485  MachineInstr *MI = Br.MI;
1486  unsigned TargetOperand = branchTargetOperand(MI);
1487  MachineBasicBlock *DestBB = MI->getOperand(TargetOperand).getMBB();
1488 
1489  // Check to see if the DestBB is already in-range.
1490  if (isBBInRange(MI, DestBB, Br.MaxDisp))
1491  return false;
1492 
1493  if (!Br.isCond)
1494  return fixupUnconditionalBr(Br);
1495  return fixupConditionalBr(Br);
1496 }
1497 
1498 /// fixupUnconditionalBr - Fix up an unconditional branch whose destination is
1499 /// too far away to fit in its displacement field. If the LR register has been
1500 /// spilled in the epilogue, then we can use BL to implement a far jump.
1501 /// Otherwise, add an intermediate branch instruction to a branch.
1502 bool
1503 MipsConstantIslands::fixupUnconditionalBr(ImmBranch &Br) {
1504  MachineInstr *MI = Br.MI;
1505  MachineBasicBlock *MBB = MI->getParent();
1506  MachineBasicBlock *DestBB = MI->getOperand(0).getMBB();
1507  // Use BL to implement far jump.
1508  unsigned BimmX16MaxDisp = ((1 << 16)-1) * 2;
1509  if (isBBInRange(MI, DestBB, BimmX16MaxDisp)) {
1510  Br.MaxDisp = BimmX16MaxDisp;
1511  MI->setDesc(TII->get(Mips::BimmX16));
1512  }
1513  else {
1514  // need to give the math a more careful look here
1515  // this is really a segment address and not
1516  // a PC relative address. FIXME. But I think that
1517  // just reducing the bits by 1 as I've done is correct.
1518  // The basic block we are branching too much be longword aligned.
1519  // we know that RA is saved because we always save it right now.
1520  // this requirement will be relaxed later but we also have an alternate
1521  // way to implement this that I will implement that does not need jal.
1522  // We should have a way to back out this alignment restriction if we "can" later.
1523  // but it is not harmful.
1524  //
1525  DestBB->setAlignment(llvm::Align(4));
1526  Br.MaxDisp = ((1<<24)-1) * 2;
1527  MI->setDesc(TII->get(Mips::JalB16));
1528  }
1529  BBInfo[MBB->getNumber()].Size += 2;
1530  adjustBBOffsetsAfter(MBB);
1531  HasFarJump = true;
1532  ++NumUBrFixed;
1533 
1534  LLVM_DEBUG(dbgs() << " Changed B to long jump " << *MI);
1535 
1536  return true;
1537 }
1538 
1539 /// fixupConditionalBr - Fix up a conditional branch whose destination is too
1540 /// far away to fit in its displacement field. It is converted to an inverse
1541 /// conditional branch + an unconditional branch to the destination.
1542 bool
1543 MipsConstantIslands::fixupConditionalBr(ImmBranch &Br) {
1544  MachineInstr *MI = Br.MI;
1545  unsigned TargetOperand = branchTargetOperand(MI);
1546  MachineBasicBlock *DestBB = MI->getOperand(TargetOperand).getMBB();
1547  unsigned Opcode = MI->getOpcode();
1548  unsigned LongFormOpcode = longformBranchOpcode(Opcode);
1549  unsigned LongFormMaxOff = branchMaxOffsets(LongFormOpcode);
1550 
1551  // Check to see if the DestBB is already in-range.
1552  if (isBBInRange(MI, DestBB, LongFormMaxOff)) {
1553  Br.MaxDisp = LongFormMaxOff;
1554  MI->setDesc(TII->get(LongFormOpcode));
1555  return true;
1556  }
1557 
1558  // Add an unconditional branch to the destination and invert the branch
1559  // condition to jump over it:
1560  // bteqz L1
1561  // =>
1562  // bnez L2
1563  // b L1
1564  // L2:
1565 
1566  // If the branch is at the end of its MBB and that has a fall-through block,
1567  // direct the updated conditional branch to the fall-through block. Otherwise,
1568  // split the MBB before the next instruction.
1569  MachineBasicBlock *MBB = MI->getParent();
1570  MachineInstr *BMI = &MBB->back();
1571  bool NeedSplit = (BMI != MI) || !BBHasFallthrough(MBB);
1572  unsigned OppositeBranchOpcode = TII->getOppositeBranchOpc(Opcode);
1573 
1574  ++NumCBrFixed;
1575  if (BMI != MI) {
1576  if (std::next(MachineBasicBlock::iterator(MI)) == std::prev(MBB->end()) &&
1577  BMI->isUnconditionalBranch()) {
1578  // Last MI in the BB is an unconditional branch. Can we simply invert the
1579  // condition and swap destinations:
1580  // beqz L1
1581  // b L2
1582  // =>
1583  // bnez L2
1584  // b L1
1585  unsigned BMITargetOperand = branchTargetOperand(BMI);
1586  MachineBasicBlock *NewDest =
1587  BMI->getOperand(BMITargetOperand).getMBB();
1588  if (isBBInRange(MI, NewDest, Br.MaxDisp)) {
1589  LLVM_DEBUG(
1590  dbgs() << " Invert Bcc condition and swap its destination with "
1591  << *BMI);
1592  MI->setDesc(TII->get(OppositeBranchOpcode));
1593  BMI->getOperand(BMITargetOperand).setMBB(DestBB);
1594  MI->getOperand(TargetOperand).setMBB(NewDest);
1595  return true;
1596  }
1597  }
1598  }
1599 
1600  if (NeedSplit) {
1601  splitBlockBeforeInstr(*MI);
1602  // No need for the branch to the next block. We're adding an unconditional
1603  // branch to the destination.
1604  int delta = TII->getInstSizeInBytes(MBB->back());
1605  BBInfo[MBB->getNumber()].Size -= delta;
1606  MBB->back().eraseFromParent();
1607  // BBInfo[SplitBB].Offset is wrong temporarily, fixed below
1608  }
1609  MachineBasicBlock *NextBB = &*++MBB->getIterator();
1610 
1611  LLVM_DEBUG(dbgs() << " Insert B to " << printMBBReference(*DestBB)
1612  << " also invert condition and change dest. to "
1613  << printMBBReference(*NextBB) << "\n");
1614 
1615  // Insert a new conditional branch and a new unconditional branch.
1616  // Also update the ImmBranch as well as adding a new entry for the new branch.
1617  if (MI->getNumExplicitOperands() == 2) {
1618  BuildMI(MBB, DebugLoc(), TII->get(OppositeBranchOpcode))
1619  .addReg(MI->getOperand(0).getReg())
1620  .addMBB(NextBB);
1621  } else {
1622  BuildMI(MBB, DebugLoc(), TII->get(OppositeBranchOpcode))
1623  .addMBB(NextBB);
1624  }
1625  Br.MI = &MBB->back();
1626  BBInfo[MBB->getNumber()].Size += TII->getInstSizeInBytes(MBB->back());
1627  BuildMI(MBB, DebugLoc(), TII->get(Br.UncondBr)).addMBB(DestBB);
1628  BBInfo[MBB->getNumber()].Size += TII->getInstSizeInBytes(MBB->back());
1629  unsigned MaxDisp = getUnconditionalBrDisp(Br.UncondBr);
1630  ImmBranches.push_back(ImmBranch(&MBB->back(), MaxDisp, false, Br.UncondBr));
1631 
1632  // Remove the old conditional branch. It may or may not still be in MBB.
1633  BBInfo[MI->getParent()->getNumber()].Size -= TII->getInstSizeInBytes(*MI);
1634  MI->eraseFromParent();
1635  adjustBBOffsetsAfter(MBB);
1636  return true;
1637 }
1638 
1639 void MipsConstantIslands::prescanForConstants() {
1640  unsigned J = 0;
1641  (void)J;
1643  MF->begin(), E = MF->end(); B != E; ++B) {
1645  B->instr_begin(), EB = B->instr_end(); I != EB; ++I) {
1646  switch(I->getDesc().getOpcode()) {
1647  case Mips::LwConstant32: {
1648  PrescannedForConstants = true;
1649  LLVM_DEBUG(dbgs() << "constant island constant " << *I << "\n");
1650  J = I->getNumOperands();
1651  LLVM_DEBUG(dbgs() << "num operands " << J << "\n");
1652  MachineOperand& Literal = I->getOperand(1);
1653  if (Literal.isImm()) {
1654  int64_t V = Literal.getImm();
1655  LLVM_DEBUG(dbgs() << "literal " << V << "\n");
1656  Type *Int32Ty =
1657  Type::getInt32Ty(MF->getFunction().getContext());
1658  const Constant *C = ConstantInt::get(Int32Ty, V);
1659  unsigned index = MCP->getConstantPoolIndex(C, 4);
1660  I->getOperand(2).ChangeToImmediate(index);
1661  LLVM_DEBUG(dbgs() << "constant island constant " << *I << "\n");
1662  I->setDesc(TII->get(Mips::LwRxPcTcp16));
1663  I->RemoveOperand(1);
1664  I->RemoveOperand(1);
1665  I->addOperand(MachineOperand::CreateCPI(index, 0));
1666  I->addOperand(MachineOperand::CreateImm(4));
1667  }
1668  break;
1669  }
1670  default:
1671  break;
1672  }
1673  }
1674  }
1675 }
1676 
1677 /// Returns a pass that converts branches to long branches.
1679  return new MipsConstantIslands();
1680 }
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:1261
unsigned Log2(Align A)
Returns the log2 of the alignment.
Definition: Alignment.h:150
uint64_t CallInst * C
A parsed version of the target data layout string in and methods for querying it. ...
Definition: DataLayout.h:111
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:476
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:124
unsigned Offset
Offset - Distance from the beginning of the function to the beginning of this basic block...
static unsigned int branchMaxOffsets(unsigned int Opcode)
STATISTIC(NumFunctions, "Total number of functions")
A debug info location.
Definition: DebugLoc.h: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.
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
const MachineInstrBuilder & addConstantPoolIndex(unsigned Idx, int Offset=0, unsigned TargetFlags=0) const
MachineInstrBundleIterator< MachineInstr, true > reverse_iterator
int getNumber() const
MachineBasicBlocks are uniquely numbered at the function level, unless they&#39;re not in a MachineFuncti...
uint64_t value() const
This is a hole in the type system and should not be abused.
Definition: Alignment.h:75
instr_iterator insert(instr_iterator I, MachineInstr *M)
Insert MI into the instruction list before I, possibly inside a bundle.
uint64_t offsetToAlignment(uint64_t Value, llvm::Align Align)
Returns the offset to the next integer (mod 2**64) that is greater than or equal to Value and is a mu...
Definition: Alignment.h:145
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
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
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...
void setAlignment(llvm::Align A)
Set alignment of the basic block.
void setMBB(MachineBasicBlock *MBB)
static MachineOperand CreateCPI(unsigned Idx, int Offset, unsigned TargetFlags=0)
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.
static constexpr const Align None()
Returns a default constructed Align which corresponds to no alignment.
Definition: Alignment.h:82
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:1186
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.
This struct is a compact representation of a valid (non-zero power of two) alignment.
Definition: Alignment.h:40
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:1146
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
unsigned Size
Size - Size of the basic block in bytes.
APFloat neg(APFloat X)
Returns the negated value of the argument.
Definition: APFloat.h:1234
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:653
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
llvm::Align getAlignment() const
Return alignment of the basic block.
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:697
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:470
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...
unsigned postOffset(llvm::Align Align=llvm::Align::None()) const
Compute the offset immediately following this block.
uint32_t Size
Definition: Profile.cpp:46
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
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