LLVM  7.0.0svn
ShrinkWrap.cpp
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1 //===- ShrinkWrap.cpp - Compute safe point for prolog/epilog insertion ----===//
2 //
3 // The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 //
10 // This pass looks for safe point where the prologue and epilogue can be
11 // inserted.
12 // The safe point for the prologue (resp. epilogue) is called Save
13 // (resp. Restore).
14 // A point is safe for prologue (resp. epilogue) if and only if
15 // it 1) dominates (resp. post-dominates) all the frame related operations and
16 // between 2) two executions of the Save (resp. Restore) point there is an
17 // execution of the Restore (resp. Save) point.
18 //
19 // For instance, the following points are safe:
20 // for (int i = 0; i < 10; ++i) {
21 // Save
22 // ...
23 // Restore
24 // }
25 // Indeed, the execution looks like Save -> Restore -> Save -> Restore ...
26 // And the following points are not:
27 // for (int i = 0; i < 10; ++i) {
28 // Save
29 // ...
30 // }
31 // for (int i = 0; i < 10; ++i) {
32 // ...
33 // Restore
34 // }
35 // Indeed, the execution looks like Save -> Save -> ... -> Restore -> Restore.
36 //
37 // This pass also ensures that the safe points are 3) cheaper than the regular
38 // entry and exits blocks.
39 //
40 // Property #1 is ensured via the use of MachineDominatorTree and
41 // MachinePostDominatorTree.
42 // Property #2 is ensured via property #1 and MachineLoopInfo, i.e., both
43 // points must be in the same loop.
44 // Property #3 is ensured via the MachineBlockFrequencyInfo.
45 //
46 // If this pass found points matching all these properties, then
47 // MachineFrameInfo is updated with this information.
48 //
49 //===----------------------------------------------------------------------===//
50 
51 #include "llvm/ADT/BitVector.h"
53 #include "llvm/ADT/SetVector.h"
54 #include "llvm/ADT/SmallVector.h"
55 #include "llvm/ADT/Statistic.h"
56 #include "llvm/Analysis/CFG.h"
75 #include "llvm/IR/Attributes.h"
76 #include "llvm/IR/Function.h"
77 #include "llvm/MC/MCAsmInfo.h"
78 #include "llvm/Pass.h"
80 #include "llvm/Support/Debug.h"
84 #include <cassert>
85 #include <cstdint>
86 #include <memory>
87 
88 using namespace llvm;
89 
90 #define DEBUG_TYPE "shrink-wrap"
91 
92 STATISTIC(NumFunc, "Number of functions");
93 STATISTIC(NumCandidates, "Number of shrink-wrapping candidates");
94 STATISTIC(NumCandidatesDropped,
95  "Number of shrink-wrapping candidates dropped because of frequency");
96 
98 EnableShrinkWrapOpt("enable-shrink-wrap", cl::Hidden,
99  cl::desc("enable the shrink-wrapping pass"));
100 
101 namespace {
102 
103 /// Class to determine where the safe point to insert the
104 /// prologue and epilogue are.
105 /// Unlike the paper from Fred C. Chow, PLDI'88, that introduces the
106 /// shrink-wrapping term for prologue/epilogue placement, this pass
107 /// does not rely on expensive data-flow analysis. Instead we use the
108 /// dominance properties and loop information to decide which point
109 /// are safe for such insertion.
110 class ShrinkWrap : public MachineFunctionPass {
111  /// Hold callee-saved information.
112  RegisterClassInfo RCI;
115 
116  /// Current safe point found for the prologue.
117  /// The prologue will be inserted before the first instruction
118  /// in this basic block.
119  MachineBasicBlock *Save;
120 
121  /// Current safe point found for the epilogue.
122  /// The epilogue will be inserted before the first terminator instruction
123  /// in this basic block.
124  MachineBasicBlock *Restore;
125 
126  /// Hold the information of the basic block frequency.
127  /// Use to check the profitability of the new points.
129 
130  /// Hold the loop information. Used to determine if Save and Restore
131  /// are in the same loop.
132  MachineLoopInfo *MLI;
133 
134  // Emit remarks.
135  MachineOptimizationRemarkEmitter *ORE = nullptr;
136 
137  /// Frequency of the Entry block.
138  uint64_t EntryFreq;
139 
140  /// Current opcode for frame setup.
141  unsigned FrameSetupOpcode;
142 
143  /// Current opcode for frame destroy.
144  unsigned FrameDestroyOpcode;
145 
146  /// Stack pointer register, used by llvm.{savestack,restorestack}
147  unsigned SP;
148 
149  /// Entry block.
150  const MachineBasicBlock *Entry;
151 
152  using SetOfRegs = SmallSetVector<unsigned, 16>;
153 
154  /// Registers that need to be saved for the current function.
155  mutable SetOfRegs CurrentCSRs;
156 
157  /// Current MachineFunction.
158  MachineFunction *MachineFunc;
159 
160  /// Check if \p MI uses or defines a callee-saved register or
161  /// a frame index. If this is the case, this means \p MI must happen
162  /// after Save and before Restore.
163  bool useOrDefCSROrFI(const MachineInstr &MI, RegScavenger *RS) const;
164 
165  const SetOfRegs &getCurrentCSRs(RegScavenger *RS) const {
166  if (CurrentCSRs.empty()) {
167  BitVector SavedRegs;
168  const TargetFrameLowering *TFI =
169  MachineFunc->getSubtarget().getFrameLowering();
170 
171  TFI->determineCalleeSaves(*MachineFunc, SavedRegs, RS);
172 
173  for (int Reg = SavedRegs.find_first(); Reg != -1;
174  Reg = SavedRegs.find_next(Reg))
175  CurrentCSRs.insert((unsigned)Reg);
176  }
177  return CurrentCSRs;
178  }
179 
180  /// Update the Save and Restore points such that \p MBB is in
181  /// the region that is dominated by Save and post-dominated by Restore
182  /// and Save and Restore still match the safe point definition.
183  /// Such point may not exist and Save and/or Restore may be null after
184  /// this call.
185  void updateSaveRestorePoints(MachineBasicBlock &MBB, RegScavenger *RS);
186 
187  /// Initialize the pass for \p MF.
188  void init(MachineFunction &MF) {
189  RCI.runOnMachineFunction(MF);
190  MDT = &getAnalysis<MachineDominatorTree>();
191  MPDT = &getAnalysis<MachinePostDominatorTree>();
192  Save = nullptr;
193  Restore = nullptr;
194  MBFI = &getAnalysis<MachineBlockFrequencyInfo>();
195  MLI = &getAnalysis<MachineLoopInfo>();
196  ORE = &getAnalysis<MachineOptimizationRemarkEmitterPass>().getORE();
197  EntryFreq = MBFI->getEntryFreq();
198  const TargetSubtargetInfo &Subtarget = MF.getSubtarget();
199  const TargetInstrInfo &TII = *Subtarget.getInstrInfo();
200  FrameSetupOpcode = TII.getCallFrameSetupOpcode();
201  FrameDestroyOpcode = TII.getCallFrameDestroyOpcode();
203  Entry = &MF.front();
204  CurrentCSRs.clear();
205  MachineFunc = &MF;
206 
207  ++NumFunc;
208  }
209 
210  /// Check whether or not Save and Restore points are still interesting for
211  /// shrink-wrapping.
212  bool ArePointsInteresting() const { return Save != Entry && Save && Restore; }
213 
214  /// Check if shrink wrapping is enabled for this target and function.
215  static bool isShrinkWrapEnabled(const MachineFunction &MF);
216 
217 public:
218  static char ID;
219 
220  ShrinkWrap() : MachineFunctionPass(ID) {
222  }
223 
224  void getAnalysisUsage(AnalysisUsage &AU) const override {
225  AU.setPreservesAll();
232  }
233 
234  MachineFunctionProperties getRequiredProperties() const override {
237  }
238 
239  StringRef getPassName() const override { return "Shrink Wrapping analysis"; }
240 
241  /// Perform the shrink-wrapping analysis and update
242  /// the MachineFrameInfo attached to \p MF with the results.
243  bool runOnMachineFunction(MachineFunction &MF) override;
244 };
245 
246 } // end anonymous namespace
247 
248 char ShrinkWrap::ID = 0;
249 
251 
252 INITIALIZE_PASS_BEGIN(ShrinkWrap, DEBUG_TYPE, "Shrink Wrap Pass", false, false)
258 INITIALIZE_PASS_END(ShrinkWrap, DEBUG_TYPE, "Shrink Wrap Pass", false, false)
259 
260 bool ShrinkWrap::useOrDefCSROrFI(const MachineInstr &MI,
261  RegScavenger *RS) const {
262  if (MI.getOpcode() == FrameSetupOpcode ||
263  MI.getOpcode() == FrameDestroyOpcode) {
264  LLVM_DEBUG(dbgs() << "Frame instruction: " << MI << '\n');
265  return true;
266  }
267  for (const MachineOperand &MO : MI.operands()) {
268  bool UseOrDefCSR = false;
269  if (MO.isReg()) {
270  // Ignore instructions like DBG_VALUE which don't read/def the register.
271  if (!MO.isDef() && !MO.readsReg())
272  continue;
273  unsigned PhysReg = MO.getReg();
274  if (!PhysReg)
275  continue;
277  "Unallocated register?!");
278  // The stack pointer is not normally described as a callee-saved register
279  // in calling convention definitions, so we need to watch for it
280  // separately. An SP mentioned by a call instruction, we can ignore,
281  // though, as it's harmless and we do not want to effectively disable tail
282  // calls by forcing the restore point to post-dominate them.
283  UseOrDefCSR = (!MI.isCall() && PhysReg == SP) ||
284  RCI.getLastCalleeSavedAlias(PhysReg);
285  } else if (MO.isRegMask()) {
286  // Check if this regmask clobbers any of the CSRs.
287  for (unsigned Reg : getCurrentCSRs(RS)) {
288  if (MO.clobbersPhysReg(Reg)) {
289  UseOrDefCSR = true;
290  break;
291  }
292  }
293  }
294  // Skip FrameIndex operands in DBG_VALUE instructions.
295  if (UseOrDefCSR || (MO.isFI() && !MI.isDebugValue())) {
296  LLVM_DEBUG(dbgs() << "Use or define CSR(" << UseOrDefCSR << ") or FI("
297  << MO.isFI() << "): " << MI << '\n');
298  return true;
299  }
300  }
301  return false;
302 }
303 
304 /// Helper function to find the immediate (post) dominator.
305 template <typename ListOfBBs, typename DominanceAnalysis>
306 static MachineBasicBlock *FindIDom(MachineBasicBlock &Block, ListOfBBs BBs,
307  DominanceAnalysis &Dom) {
308  MachineBasicBlock *IDom = &Block;
309  for (MachineBasicBlock *BB : BBs) {
310  IDom = Dom.findNearestCommonDominator(IDom, BB);
311  if (!IDom)
312  break;
313  }
314  if (IDom == &Block)
315  return nullptr;
316  return IDom;
317 }
318 
319 void ShrinkWrap::updateSaveRestorePoints(MachineBasicBlock &MBB,
320  RegScavenger *RS) {
321  // Get rid of the easy cases first.
322  if (!Save)
323  Save = &MBB;
324  else
325  Save = MDT->findNearestCommonDominator(Save, &MBB);
326 
327  if (!Save) {
328  LLVM_DEBUG(dbgs() << "Found a block that is not reachable from Entry\n");
329  return;
330  }
331 
332  if (!Restore)
333  Restore = &MBB;
334  else if (MPDT->getNode(&MBB)) // If the block is not in the post dom tree, it
335  // means the block never returns. If that's the
336  // case, we don't want to call
337  // `findNearestCommonDominator`, which will
338  // return `Restore`.
339  Restore = MPDT->findNearestCommonDominator(Restore, &MBB);
340  else
341  Restore = nullptr; // Abort, we can't find a restore point in this case.
342 
343  // Make sure we would be able to insert the restore code before the
344  // terminator.
345  if (Restore == &MBB) {
346  for (const MachineInstr &Terminator : MBB.terminators()) {
347  if (!useOrDefCSROrFI(Terminator, RS))
348  continue;
349  // One of the terminator needs to happen before the restore point.
350  if (MBB.succ_empty()) {
351  Restore = nullptr; // Abort, we can't find a restore point in this case.
352  break;
353  }
354  // Look for a restore point that post-dominates all the successors.
355  // The immediate post-dominator is what we are looking for.
356  Restore = FindIDom<>(*Restore, Restore->successors(), *MPDT);
357  break;
358  }
359  }
360 
361  if (!Restore) {
362  LLVM_DEBUG(
363  dbgs() << "Restore point needs to be spanned on several blocks\n");
364  return;
365  }
366 
367  // Make sure Save and Restore are suitable for shrink-wrapping:
368  // 1. all path from Save needs to lead to Restore before exiting.
369  // 2. all path to Restore needs to go through Save from Entry.
370  // We achieve that by making sure that:
371  // A. Save dominates Restore.
372  // B. Restore post-dominates Save.
373  // C. Save and Restore are in the same loop.
374  bool SaveDominatesRestore = false;
375  bool RestorePostDominatesSave = false;
376  while (Save && Restore &&
377  (!(SaveDominatesRestore = MDT->dominates(Save, Restore)) ||
378  !(RestorePostDominatesSave = MPDT->dominates(Restore, Save)) ||
379  // Post-dominance is not enough in loops to ensure that all uses/defs
380  // are after the prologue and before the epilogue at runtime.
381  // E.g.,
382  // while(1) {
383  // Save
384  // Restore
385  // if (...)
386  // break;
387  // use/def CSRs
388  // }
389  // All the uses/defs of CSRs are dominated by Save and post-dominated
390  // by Restore. However, the CSRs uses are still reachable after
391  // Restore and before Save are executed.
392  //
393  // For now, just push the restore/save points outside of loops.
394  // FIXME: Refine the criteria to still find interesting cases
395  // for loops.
396  MLI->getLoopFor(Save) || MLI->getLoopFor(Restore))) {
397  // Fix (A).
398  if (!SaveDominatesRestore) {
399  Save = MDT->findNearestCommonDominator(Save, Restore);
400  continue;
401  }
402  // Fix (B).
403  if (!RestorePostDominatesSave)
404  Restore = MPDT->findNearestCommonDominator(Restore, Save);
405 
406  // Fix (C).
407  if (Save && Restore &&
408  (MLI->getLoopFor(Save) || MLI->getLoopFor(Restore))) {
409  if (MLI->getLoopDepth(Save) > MLI->getLoopDepth(Restore)) {
410  // Push Save outside of this loop if immediate dominator is different
411  // from save block. If immediate dominator is not different, bail out.
412  Save = FindIDom<>(*Save, Save->predecessors(), *MDT);
413  if (!Save)
414  break;
415  } else {
416  // If the loop does not exit, there is no point in looking
417  // for a post-dominator outside the loop.
419  MLI->getLoopFor(Restore)->getExitingBlocks(ExitBlocks);
420  // Push Restore outside of this loop.
421  // Look for the immediate post-dominator of the loop exits.
422  MachineBasicBlock *IPdom = Restore;
423  for (MachineBasicBlock *LoopExitBB: ExitBlocks) {
424  IPdom = FindIDom<>(*IPdom, LoopExitBB->successors(), *MPDT);
425  if (!IPdom)
426  break;
427  }
428  // If the immediate post-dominator is not in a less nested loop,
429  // then we are stuck in a program with an infinite loop.
430  // In that case, we will not find a safe point, hence, bail out.
431  if (IPdom && MLI->getLoopDepth(IPdom) < MLI->getLoopDepth(Restore))
432  Restore = IPdom;
433  else {
434  Restore = nullptr;
435  break;
436  }
437  }
438  }
439  }
440 }
441 
443  StringRef RemarkName, StringRef RemarkMessage,
444  const DiagnosticLocation &Loc,
445  const MachineBasicBlock *MBB) {
446  ORE->emit([&]() {
447  return MachineOptimizationRemarkMissed(DEBUG_TYPE, RemarkName, Loc, MBB)
448  << RemarkMessage;
449  });
450 
451  LLVM_DEBUG(dbgs() << RemarkMessage << '\n');
452  return false;
453 }
454 
455 bool ShrinkWrap::runOnMachineFunction(MachineFunction &MF) {
456  if (skipFunction(MF.getFunction()) || MF.empty() || !isShrinkWrapEnabled(MF))
457  return false;
458 
459  LLVM_DEBUG(dbgs() << "**** Analysing " << MF.getName() << '\n');
460 
461  init(MF);
462 
464  if (containsIrreducibleCFG<MachineBasicBlock *>(RPOT, *MLI)) {
465  // If MF is irreducible, a block may be in a loop without
466  // MachineLoopInfo reporting it. I.e., we may use the
467  // post-dominance property in loops, which lead to incorrect
468  // results. Moreover, we may miss that the prologue and
469  // epilogue are not in the same loop, leading to unbalanced
470  // construction/deconstruction of the stack frame.
471  return giveUpWithRemarks(ORE, "UnsupportedIrreducibleCFG",
472  "Irreducible CFGs are not supported yet.",
473  MF.getFunction().getSubprogram(), &MF.front());
474  }
475 
477  std::unique_ptr<RegScavenger> RS(
478  TRI->requiresRegisterScavenging(MF) ? new RegScavenger() : nullptr);
479 
480  for (MachineBasicBlock &MBB : MF) {
481  LLVM_DEBUG(dbgs() << "Look into: " << MBB.getNumber() << ' '
482  << MBB.getName() << '\n');
483 
484  if (MBB.isEHFuncletEntry())
485  return giveUpWithRemarks(ORE, "UnsupportedEHFunclets",
486  "EH Funclets are not supported yet.",
487  MBB.front().getDebugLoc(), &MBB);
488 
489  if (MBB.isEHPad()) {
490  // Push the prologue and epilogue outside of
491  // the region that may throw by making sure
492  // that all the landing pads are at least at the
493  // boundary of the save and restore points.
494  // The problem with exceptions is that the throw
495  // is not properly modeled and in particular, a
496  // basic block can jump out from the middle.
497  updateSaveRestorePoints(MBB, RS.get());
498  if (!ArePointsInteresting()) {
499  LLVM_DEBUG(dbgs() << "EHPad prevents shrink-wrapping\n");
500  return false;
501  }
502  continue;
503  }
504 
505  for (const MachineInstr &MI : MBB) {
506  if (!useOrDefCSROrFI(MI, RS.get()))
507  continue;
508  // Save (resp. restore) point must dominate (resp. post dominate)
509  // MI. Look for the proper basic block for those.
510  updateSaveRestorePoints(MBB, RS.get());
511  // If we are at a point where we cannot improve the placement of
512  // save/restore instructions, just give up.
513  if (!ArePointsInteresting()) {
514  LLVM_DEBUG(dbgs() << "No Shrink wrap candidate found\n");
515  return false;
516  }
517  // No need to look for other instructions, this basic block
518  // will already be part of the handled region.
519  break;
520  }
521  }
522  if (!ArePointsInteresting()) {
523  // If the points are not interesting at this point, then they must be null
524  // because it means we did not encounter any frame/CSR related code.
525  // Otherwise, we would have returned from the previous loop.
526  assert(!Save && !Restore && "We miss a shrink-wrap opportunity?!");
527  LLVM_DEBUG(dbgs() << "Nothing to shrink-wrap\n");
528  return false;
529  }
530 
531  LLVM_DEBUG(dbgs() << "\n ** Results **\nFrequency of the Entry: " << EntryFreq
532  << '\n');
533 
534  const TargetFrameLowering *TFI = MF.getSubtarget().getFrameLowering();
535  do {
536  LLVM_DEBUG(dbgs() << "Shrink wrap candidates (#, Name, Freq):\nSave: "
537  << Save->getNumber() << ' ' << Save->getName() << ' '
538  << MBFI->getBlockFreq(Save).getFrequency()
539  << "\nRestore: " << Restore->getNumber() << ' '
540  << Restore->getName() << ' '
541  << MBFI->getBlockFreq(Restore).getFrequency() << '\n');
542 
543  bool IsSaveCheap, TargetCanUseSaveAsPrologue = false;
544  if (((IsSaveCheap = EntryFreq >= MBFI->getBlockFreq(Save).getFrequency()) &&
545  EntryFreq >= MBFI->getBlockFreq(Restore).getFrequency()) &&
546  ((TargetCanUseSaveAsPrologue = TFI->canUseAsPrologue(*Save)) &&
547  TFI->canUseAsEpilogue(*Restore)))
548  break;
549  LLVM_DEBUG(
550  dbgs() << "New points are too expensive or invalid for the target\n");
551  MachineBasicBlock *NewBB;
552  if (!IsSaveCheap || !TargetCanUseSaveAsPrologue) {
553  Save = FindIDom<>(*Save, Save->predecessors(), *MDT);
554  if (!Save)
555  break;
556  NewBB = Save;
557  } else {
558  // Restore is expensive.
559  Restore = FindIDom<>(*Restore, Restore->successors(), *MPDT);
560  if (!Restore)
561  break;
562  NewBB = Restore;
563  }
564  updateSaveRestorePoints(*NewBB, RS.get());
565  } while (Save && Restore);
566 
567  if (!ArePointsInteresting()) {
568  ++NumCandidatesDropped;
569  return false;
570  }
571 
572  LLVM_DEBUG(dbgs() << "Final shrink wrap candidates:\nSave: "
573  << Save->getNumber() << ' ' << Save->getName()
574  << "\nRestore: " << Restore->getNumber() << ' '
575  << Restore->getName() << '\n');
576 
577  MachineFrameInfo &MFI = MF.getFrameInfo();
578  MFI.setSavePoint(Save);
579  MFI.setRestorePoint(Restore);
580  ++NumCandidates;
581  return false;
582 }
583 
584 bool ShrinkWrap::isShrinkWrapEnabled(const MachineFunction &MF) {
586 
587  switch (EnableShrinkWrapOpt) {
588  case cl::BOU_UNSET:
589  return TFI->enableShrinkWrapping(MF) &&
590  // Windows with CFI has some limitations that make it impossible
591  // to use shrink-wrapping.
593  // Sanitizers look at the value of the stack at the location
594  // of the crash. Since a crash can happen anywhere, the
595  // frame must be lowered before anything else happen for the
596  // sanitizers to be able to get a correct stack frame.
597  !(MF.getFunction().hasFnAttribute(Attribute::SanitizeAddress) ||
598  MF.getFunction().hasFnAttribute(Attribute::SanitizeThread) ||
599  MF.getFunction().hasFnAttribute(Attribute::SanitizeMemory) ||
600  MF.getFunction().hasFnAttribute(Attribute::SanitizeHWAddress));
601  // If EnableShrinkWrap is set, it takes precedence on whatever the
602  // target sets. The rational is that we assume we want to test
603  // something related to shrink-wrapping.
604  case cl::BOU_TRUE:
605  return true;
606  case cl::BOU_FALSE:
607  return false;
608  }
609  llvm_unreachable("Invalid shrink-wrapping state");
610 }
Pass interface - Implemented by all &#39;passes&#39;.
Definition: Pass.h:81
bool usesWindowsCFI() const
Definition: MCAsmInfo.h:579
void setSavePoint(MachineBasicBlock *NewSave)
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
virtual bool enableShrinkWrapping(const MachineFunction &MF) const
Returns true if the target will correctly handle shrink wrapping.
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
virtual const TargetRegisterInfo * getRegisterInfo() const
getRegisterInfo - If register information is available, return it.
const DebugLoc & getDebugLoc() const
Returns the debug location id of this MachineInstr.
Definition: MachineInstr.h:285
unsigned Reg
virtual const TargetLowering * getTargetLowering() const
uint64_t getFrequency() const
Returns the frequency as a fixpoint number scaled by the entry frequency.
MachineBlockFrequencyInfo pass uses BlockFrequencyInfoImpl implementation to estimate machine basic b...
bool hasFnAttribute(Attribute::AttrKind Kind) const
Return true if the function has the attribute.
Definition: Function.h:307
STATISTIC(NumFunctions, "Total number of functions")
unsigned const TargetRegisterInfo * TRI
unsigned getCallFrameDestroyOpcode() const
iterator_range< succ_iterator > successors()
virtual void determineCalleeSaves(MachineFunction &MF, BitVector &SavedRegs, RegScavenger *RS=nullptr) const
This method determines which of the registers reported by TargetRegisterInfo::getCalleeSavedRegs() sh...
void emit(DiagnosticInfoOptimizationBase &OptDiag)
Emit an optimization remark.
AnalysisUsage & addRequired()
#define INITIALIZE_PASS_DEPENDENCY(depName)
Definition: PassSupport.h:51
MachineFunctionPass - This class adapts the FunctionPass interface to allow convenient creation of pa...
const HexagonInstrInfo * TII
virtual bool canUseAsEpilogue(const MachineBasicBlock &MBB) const
Check whether or not the given MBB can be used as a epilogue for the target.
int find_first() const
find_first - Returns the index of the first set bit, -1 if none of the bits are set.
Definition: BitVector.h:332
const TargetMachine & getTarget() const
getTarget - Return the target machine this machine code is compiled with
int find_next(unsigned Prev) const
find_next - Returns the index of the next set bit following the "Prev" bit.
Definition: BitVector.h:340
This file contains the simple types necessary to represent the attributes associated with functions a...
iterator_range< iterator > terminators()
The MachineFrameInfo class represents an abstract stack frame until prolog/epilog code is inserted...
#define DEBUG_TYPE
Definition: ShrinkWrap.cpp:90
int getNumber() const
MachineBasicBlocks are uniquely numbered at the function level, unless they&#39;re not in a MachineFuncti...
virtual const TargetInstrInfo * getInstrInfo() const
MachineBasicBlock * findNearestCommonDominator(MachineBasicBlock *A, MachineBasicBlock *B)
findNearestCommonDominator - Find nearest common dominator basic block for basic block A and B...
StringRef getName() const
getName - Return the name of the corresponding LLVM function.
TargetInstrInfo - Interface to description of machine instruction set.
===- MachineOptimizationRemarkEmitter.h - Opt Diagnostics -*- C++ -*-—===//
initializer< Ty > init(const Ty &Val)
Definition: CommandLine.h:410
This file declares the machine register scavenger class.
StringRef getName() const
Return the name of the corresponding LLVM basic block, or an empty string.
const TargetSubtargetInfo & getSubtarget() const
getSubtarget - Return the subtarget for which this machine code is being compiled.
void getAnalysisUsage(AnalysisUsage &AU) const override
getAnalysisUsage - Subclasses that override getAnalysisUsage must call this.
DISubprogram * getSubprogram() const
Get the attached subprogram.
Definition: Metadata.cpp:1508
static cl::opt< cl::boolOrDefault > EnableShrinkWrapOpt("enable-shrink-wrap", cl::Hidden, cl::desc("enable the shrink-wrapping pass"))
const MCAsmInfo * getMCAsmInfo() const
Return target specific asm information.
BlockFrequency getBlockFreq(const MachineBasicBlock *MBB) const
getblockFreq - Return block frequency.
unsigned getCallFrameSetupOpcode() const
These methods return the opcode of the frame setup/destroy instructions if they exist (-1 otherwise)...
Represent the analysis usage information of a pass.
void runOnMachineFunction(const MachineFunction &MF)
runOnFunction - Prepare to answer questions about MF.
void initializeShrinkWrapPass(PassRegistry &)
TargetRegisterInfo base class - We assume that the target defines a static array of TargetRegisterDes...
const MachineBasicBlock & front() const
static MachineBasicBlock * FindIDom(MachineBasicBlock &Block, ListOfBBs BBs, DominanceAnalysis &Dom)
Helper function to find the immediate (post) dominator.
Definition: ShrinkWrap.cpp:306
INITIALIZE_PASS_END(RegBankSelect, DEBUG_TYPE, "Assign register bank of generic virtual registers", false, false) RegBankSelect
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
A SetVector that performs no allocations if smaller than a certain size.
Definition: SetVector.h:298
The optimization diagnostic interface.
PostDominatorTree Class - Concrete subclass of DominatorTree that is used to compute the post-dominat...
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:861
bool dominates(const MachineDomTreeNode *A, const MachineDomTreeNode *B) const
Information about stack frame layout on the target.
#define INITIALIZE_PASS_BEGIN(passName, arg, name, cfg, analysis)
Definition: PassSupport.h:48
const Function & getFunction() const
Return the LLVM function that this machine code represents.
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:133
void setPreservesAll()
Set by analyses that do not transform their input at all.
MachineFunctionProperties & set(Property P)
TargetSubtargetInfo - Generic base class for all target subtargets.
Representation of each machine instruction.
Definition: MachineInstr.h:60
static bool giveUpWithRemarks(MachineOptimizationRemarkEmitter *ORE, StringRef RemarkName, StringRef RemarkMessage, const DiagnosticLocation &Loc, const MachineBasicBlock *MBB)
Definition: ShrinkWrap.cpp:442
static bool isPhysicalRegister(unsigned Reg)
Return true if the specified register number is in the physical register namespace.
bool isEHPad() const
Returns true if the block is a landing pad.
bool isEHFuncletEntry() const
Returns true if this is the entry block of an EH funclet.
virtual const TargetFrameLowering * getFrameLowering() const
virtual bool canUseAsPrologue(const MachineBasicBlock &MBB) const
Check whether or not the given MBB can be used as a prologue for the target.
unsigned getLastCalleeSavedAlias(unsigned PhysReg) const
getLastCalleeSavedAlias - Returns the last callee saved register that overlaps PhysReg, or 0 if Reg doesn&#39;t overlap a CalleeSavedAliases.
Diagnostic information for missed-optimization remarks.
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
aarch64 promote const
unsigned getStackPointerRegisterToSaveRestore() const
If a physical register, this specifies the register that llvm.savestack/llvm.restorestack should save...
IRTranslator LLVM IR MI
char & ShrinkWrapID
ShrinkWrap pass. Look for the best place to insert save and restore.
Definition: ShrinkWrap.cpp:250
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49
#define LLVM_DEBUG(X)
Definition: Debug.h:119
DominatorTree Class - Concrete subclass of DominatorTreeBase that is used to compute a normal dominat...
Properties which a MachineFunction may have at a given point in time.
This file describes how to lower LLVM code to machine code.