LLVM  6.0.0svn
CoroFrame.cpp
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1 //===- CoroFrame.cpp - Builds and manipulates coroutine frame -------------===//
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 // This file contains classes used to discover if for a particular value
10 // there from sue to definition that crosses a suspend block.
11 //
12 // Using the information discovered we form a Coroutine Frame structure to
13 // contain those values. All uses of those values are replaced with appropriate
14 // GEP + load from the coroutine frame. At the point of the definition we spill
15 // the value into the coroutine frame.
16 //
17 // TODO: pack values tightly using liveness info.
18 //===----------------------------------------------------------------------===//
19 
20 #include "CoroInternal.h"
21 #include "llvm/ADT/BitVector.h"
22 #include "llvm/IR/CFG.h"
23 #include "llvm/IR/Dominators.h"
24 #include "llvm/IR/IRBuilder.h"
25 #include "llvm/IR/InstIterator.h"
26 #include "llvm/Support/Debug.h"
31 
32 using namespace llvm;
33 
34 // The "coro-suspend-crossing" flag is very noisy. There is another debug type,
35 // "coro-frame", which results in leaner debug spew.
36 #define DEBUG_TYPE "coro-suspend-crossing"
37 
38 enum { SmallVectorThreshold = 32 };
39 
40 // Provides two way mapping between the blocks and numbers.
41 namespace {
42 class BlockToIndexMapping {
44 
45 public:
46  size_t size() const { return V.size(); }
47 
48  BlockToIndexMapping(Function &F) {
49  for (BasicBlock &BB : F)
50  V.push_back(&BB);
51  std::sort(V.begin(), V.end());
52  }
53 
54  size_t blockToIndex(BasicBlock *BB) const {
55  auto *I = std::lower_bound(V.begin(), V.end(), BB);
56  assert(I != V.end() && *I == BB && "BasicBlockNumberng: Unknown block");
57  return I - V.begin();
58  }
59 
60  BasicBlock *indexToBlock(unsigned Index) const { return V[Index]; }
61 };
62 } // end anonymous namespace
63 
64 // The SuspendCrossingInfo maintains data that allows to answer a question
65 // whether given two BasicBlocks A and B there is a path from A to B that
66 // passes through a suspend point.
67 //
68 // For every basic block 'i' it maintains a BlockData that consists of:
69 // Consumes: a bit vector which contains a set of indices of blocks that can
70 // reach block 'i'
71 // Kills: a bit vector which contains a set of indices of blocks that can
72 // reach block 'i', but one of the path will cross a suspend point
73 // Suspend: a boolean indicating whether block 'i' contains a suspend point.
74 // End: a boolean indicating whether block 'i' contains a coro.end intrinsic.
75 //
76 namespace {
77 struct SuspendCrossingInfo {
78  BlockToIndexMapping Mapping;
79 
80  struct BlockData {
81  BitVector Consumes;
82  BitVector Kills;
83  bool Suspend = false;
84  bool End = false;
85  };
87 
88  iterator_range<succ_iterator> successors(BlockData const &BD) const {
89  BasicBlock *BB = Mapping.indexToBlock(&BD - &Block[0]);
90  return llvm::successors(BB);
91  }
92 
93  BlockData &getBlockData(BasicBlock *BB) {
94  return Block[Mapping.blockToIndex(BB)];
95  }
96 
97  void dump() const;
98  void dump(StringRef Label, BitVector const &BV) const;
99 
100  SuspendCrossingInfo(Function &F, coro::Shape &Shape);
101 
102  bool hasPathCrossingSuspendPoint(BasicBlock *DefBB, BasicBlock *UseBB) const {
103  size_t const DefIndex = Mapping.blockToIndex(DefBB);
104  size_t const UseIndex = Mapping.blockToIndex(UseBB);
105 
106  assert(Block[UseIndex].Consumes[DefIndex] && "use must consume def");
107  bool const Result = Block[UseIndex].Kills[DefIndex];
108  DEBUG(dbgs() << UseBB->getName() << " => " << DefBB->getName()
109  << " answer is " << Result << "\n");
110  return Result;
111  }
112 
113  bool isDefinitionAcrossSuspend(BasicBlock *DefBB, User *U) const {
114  auto *I = cast<Instruction>(U);
115 
116  // We rewrote PHINodes, so that only the ones with exactly one incoming
117  // value need to be analyzed.
118  if (auto *PN = dyn_cast<PHINode>(I))
119  if (PN->getNumIncomingValues() > 1)
120  return false;
121 
122  BasicBlock *UseBB = I->getParent();
123  return hasPathCrossingSuspendPoint(DefBB, UseBB);
124  }
125 
126  bool isDefinitionAcrossSuspend(Argument &A, User *U) const {
127  return isDefinitionAcrossSuspend(&A.getParent()->getEntryBlock(), U);
128  }
129 
130  bool isDefinitionAcrossSuspend(Instruction &I, User *U) const {
131  return isDefinitionAcrossSuspend(I.getParent(), U);
132  }
133 };
134 } // end anonymous namespace
135 
136 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
138  BitVector const &BV) const {
139  dbgs() << Label << ":";
140  for (size_t I = 0, N = BV.size(); I < N; ++I)
141  if (BV[I])
142  dbgs() << " " << Mapping.indexToBlock(I)->getName();
143  dbgs() << "\n";
144 }
145 
147  for (size_t I = 0, N = Block.size(); I < N; ++I) {
148  BasicBlock *const B = Mapping.indexToBlock(I);
149  dbgs() << B->getName() << ":\n";
150  dump(" Consumes", Block[I].Consumes);
151  dump(" Kills", Block[I].Kills);
152  }
153  dbgs() << "\n";
154 }
155 #endif
156 
157 SuspendCrossingInfo::SuspendCrossingInfo(Function &F, coro::Shape &Shape)
158  : Mapping(F) {
159  const size_t N = Mapping.size();
160  Block.resize(N);
161 
162  // Initialize every block so that it consumes itself
163  for (size_t I = 0; I < N; ++I) {
164  auto &B = Block[I];
165  B.Consumes.resize(N);
166  B.Kills.resize(N);
167  B.Consumes.set(I);
168  }
169 
170  // Mark all CoroEnd Blocks. We do not propagate Kills beyond coro.ends as
171  // the code beyond coro.end is reachable during initial invocation of the
172  // coroutine.
173  for (auto *CE : Shape.CoroEnds)
174  getBlockData(CE->getParent()).End = true;
175 
176  // Mark all suspend blocks and indicate that they kill everything they
177  // consume. Note, that crossing coro.save also requires a spill, as any code
178  // between coro.save and coro.suspend may resume the coroutine and all of the
179  // state needs to be saved by that time.
180  auto markSuspendBlock = [&](IntrinsicInst *BarrierInst) {
181  BasicBlock *SuspendBlock = BarrierInst->getParent();
182  auto &B = getBlockData(SuspendBlock);
183  B.Suspend = true;
184  B.Kills |= B.Consumes;
185  };
186  for (CoroSuspendInst *CSI : Shape.CoroSuspends) {
187  markSuspendBlock(CSI);
188  markSuspendBlock(CSI->getCoroSave());
189  }
190 
191  // Iterate propagating consumes and kills until they stop changing.
192  int Iteration = 0;
193  (void)Iteration;
194 
195  bool Changed;
196  do {
197  DEBUG(dbgs() << "iteration " << ++Iteration);
198  DEBUG(dbgs() << "==============\n");
199 
200  Changed = false;
201  for (size_t I = 0; I < N; ++I) {
202  auto &B = Block[I];
203  for (BasicBlock *SI : successors(B)) {
204 
205  auto SuccNo = Mapping.blockToIndex(SI);
206 
207  // Saved Consumes and Kills bitsets so that it is easy to see
208  // if anything changed after propagation.
209  auto &S = Block[SuccNo];
210  auto SavedConsumes = S.Consumes;
211  auto SavedKills = S.Kills;
212 
213  // Propagate Kills and Consumes from block B into its successor S.
214  S.Consumes |= B.Consumes;
215  S.Kills |= B.Kills;
216 
217  // If block B is a suspend block, it should propagate kills into the
218  // its successor for every block B consumes.
219  if (B.Suspend) {
220  S.Kills |= B.Consumes;
221  }
222  if (S.Suspend) {
223  // If block S is a suspend block, it should kill all of the blocks it
224  // consumes.
225  S.Kills |= S.Consumes;
226  } else if (S.End) {
227  // If block S is an end block, it should not propagate kills as the
228  // blocks following coro.end() are reached during initial invocation
229  // of the coroutine while all the data are still available on the
230  // stack or in the registers.
231  S.Kills.reset();
232  } else {
233  // This is reached when S block it not Suspend nor coro.end and it
234  // need to make sure that it is not in the kill set.
235  S.Kills.reset(SuccNo);
236  }
237 
238  // See if anything changed.
239  Changed |= (S.Kills != SavedKills) || (S.Consumes != SavedConsumes);
240 
241  if (S.Kills != SavedKills) {
242  DEBUG(dbgs() << "\nblock " << I << " follower " << SI->getName()
243  << "\n");
244  DEBUG(dump("S.Kills", S.Kills));
245  DEBUG(dump("SavedKills", SavedKills));
246  }
247  if (S.Consumes != SavedConsumes) {
248  DEBUG(dbgs() << "\nblock " << I << " follower " << SI << "\n");
249  DEBUG(dump("S.Consume", S.Consumes));
250  DEBUG(dump("SavedCons", SavedConsumes));
251  }
252  }
253  }
254  } while (Changed);
255  DEBUG(dump());
256 }
257 
258 #undef DEBUG_TYPE // "coro-suspend-crossing"
259 #define DEBUG_TYPE "coro-frame"
260 
261 // We build up the list of spills for every case where a use is separated
262 // from the definition by a suspend point.
263 
264 namespace {
265 class Spill {
266  Value *Def;
267  Instruction *User;
268 
269 public:
270  Spill(Value *Def, llvm::User *U) : Def(Def), User(cast<Instruction>(U)) {}
271 
272  Value *def() const { return Def; }
273  Instruction *user() const { return User; }
274  BasicBlock *userBlock() const { return User->getParent(); }
275 };
276 } // namespace
277 
278 // Note that there may be more than one record with the same value of Def in
279 // the SpillInfo vector.
281 
282 #ifndef NDEBUG
283 static void dump(StringRef Title, SpillInfo const &Spills) {
284  dbgs() << "------------- " << Title << "--------------\n";
285  Value *CurrentValue = nullptr;
286  for (auto const &E : Spills) {
287  if (CurrentValue != E.def()) {
288  CurrentValue = E.def();
289  CurrentValue->dump();
290  }
291  dbgs() << " user: ";
292  E.user()->dump();
293  }
294 }
295 #endif
296 
297 // Build a struct that will keep state for an active coroutine.
298 // struct f.frame {
299 // ResumeFnTy ResumeFnAddr;
300 // ResumeFnTy DestroyFnAddr;
301 // int ResumeIndex;
302 // ... promise (if present) ...
303 // ... spills ...
304 // };
306  SpillInfo &Spills) {
307  LLVMContext &C = F.getContext();
309  Name.append(".Frame");
310  StructType *FrameTy = StructType::create(C, Name);
311  auto *FramePtrTy = FrameTy->getPointerTo();
312  auto *FnTy = FunctionType::get(Type::getVoidTy(C), FramePtrTy,
313  /*IsVarArgs=*/false);
314  auto *FnPtrTy = FnTy->getPointerTo();
315 
316  // Figure out how wide should be an integer type storing the suspend index.
317  unsigned IndexBits = std::max(1U, Log2_64_Ceil(Shape.CoroSuspends.size()));
318  Type *PromiseType = Shape.PromiseAlloca
319  ? Shape.PromiseAlloca->getType()->getElementType()
320  : Type::getInt1Ty(C);
321  SmallVector<Type *, 8> Types{FnPtrTy, FnPtrTy, PromiseType,
322  Type::getIntNTy(C, IndexBits)};
323  Value *CurrentDef = nullptr;
324 
325  // Create an entry for every spilled value.
326  for (auto const &S : Spills) {
327  if (CurrentDef == S.def())
328  continue;
329 
330  CurrentDef = S.def();
331  // PromiseAlloca was already added to Types array earlier.
332  if (CurrentDef == Shape.PromiseAlloca)
333  continue;
334 
335  Type *Ty = nullptr;
336  if (auto *AI = dyn_cast<AllocaInst>(CurrentDef))
337  Ty = AI->getAllocatedType();
338  else
339  Ty = CurrentDef->getType();
340 
341  Types.push_back(Ty);
342  }
343  FrameTy->setBody(Types);
344 
345  return FrameTy;
346 }
347 
348 // We need to make room to insert a spill after initial PHIs, but before
349 // catchswitch instruction. Placing it before violates the requirement that
350 // catchswitch, like all other EHPads must be the first nonPHI in a block.
351 //
352 // Split away catchswitch into a separate block and insert in its place:
353 //
354 // cleanuppad <InsertPt> cleanupret.
355 //
356 // cleanupret instruction will act as an insert point for the spill.
358  BasicBlock *CurrentBlock = CatchSwitch->getParent();
359  BasicBlock *NewBlock = CurrentBlock->splitBasicBlock(CatchSwitch);
360  CurrentBlock->getTerminator()->eraseFromParent();
361 
362  auto *CleanupPad =
363  CleanupPadInst::Create(CatchSwitch->getParentPad(), {}, "", CurrentBlock);
364  auto *CleanupRet =
365  CleanupReturnInst::Create(CleanupPad, NewBlock, CurrentBlock);
366  return CleanupRet;
367 }
368 
369 // Replace all alloca and SSA values that are accessed across suspend points
370 // with GetElementPointer from coroutine frame + loads and stores. Create an
371 // AllocaSpillBB that will become the new entry block for the resume parts of
372 // the coroutine:
373 //
374 // %hdl = coro.begin(...)
375 // whatever
376 //
377 // becomes:
378 //
379 // %hdl = coro.begin(...)
380 // %FramePtr = bitcast i8* hdl to %f.frame*
381 // br label %AllocaSpillBB
382 //
383 // AllocaSpillBB:
384 // ; geps corresponding to allocas that were moved to coroutine frame
385 // br label PostSpill
386 //
387 // PostSpill:
388 // whatever
389 //
390 //
391 static Instruction *insertSpills(SpillInfo &Spills, coro::Shape &Shape) {
392  auto *CB = Shape.CoroBegin;
393  IRBuilder<> Builder(CB->getNextNode());
394  PointerType *FramePtrTy = Shape.FrameTy->getPointerTo();
395  auto *FramePtr =
396  cast<Instruction>(Builder.CreateBitCast(CB, FramePtrTy, "FramePtr"));
397  Type *FrameTy = FramePtrTy->getElementType();
398 
399  Value *CurrentValue = nullptr;
400  BasicBlock *CurrentBlock = nullptr;
401  Value *CurrentReload = nullptr;
402  unsigned Index = coro::Shape::LastKnownField;
403 
404  // We need to keep track of any allocas that need "spilling"
405  // since they will live in the coroutine frame now, all access to them
406  // need to be changed, not just the access across suspend points
407  // we remember allocas and their indices to be handled once we processed
408  // all the spills.
410  // Promise alloca (if present) has a fixed field number (Shape::PromiseField)
411  if (Shape.PromiseAlloca)
413 
414  // Create a load instruction to reload the spilled value from the coroutine
415  // frame.
416  auto CreateReload = [&](Instruction *InsertBefore) {
417  Builder.SetInsertPoint(InsertBefore);
418  auto *G = Builder.CreateConstInBoundsGEP2_32(FrameTy, FramePtr, 0, Index,
419  CurrentValue->getName() +
420  Twine(".reload.addr"));
421  return isa<AllocaInst>(CurrentValue)
422  ? G
423  : Builder.CreateLoad(G,
424  CurrentValue->getName() + Twine(".reload"));
425  };
426 
427  for (auto const &E : Spills) {
428  // If we have not seen the value, generate a spill.
429  if (CurrentValue != E.def()) {
430  CurrentValue = E.def();
431  CurrentBlock = nullptr;
432  CurrentReload = nullptr;
433 
434  ++Index;
435 
436  if (auto *AI = dyn_cast<AllocaInst>(CurrentValue)) {
437  // Spilled AllocaInst will be replaced with GEP from the coroutine frame
438  // there is no spill required.
439  Allocas.emplace_back(AI, Index);
440  if (!AI->isStaticAlloca())
441  report_fatal_error("Coroutines cannot handle non static allocas yet");
442  } else {
443  // Otherwise, create a store instruction storing the value into the
444  // coroutine frame.
445 
446  Instruction *InsertPt = nullptr;
447  if (isa<Argument>(CurrentValue)) {
448  // For arguments, we will place the store instruction right after
449  // the coroutine frame pointer instruction, i.e. bitcast of
450  // coro.begin from i8* to %f.frame*.
451  InsertPt = FramePtr->getNextNode();
452  } else if (auto *II = dyn_cast<InvokeInst>(CurrentValue)) {
453  // If we are spilling the result of the invoke instruction, split the
454  // normal edge and insert the spill in the new block.
455  auto NewBB = SplitEdge(II->getParent(), II->getNormalDest());
456  InsertPt = NewBB->getTerminator();
457  } else if (dyn_cast<PHINode>(CurrentValue)) {
458  // Skip the PHINodes and EH pads instructions.
459  BasicBlock *DefBlock = cast<Instruction>(E.def())->getParent();
460  if (auto *CSI = dyn_cast<CatchSwitchInst>(DefBlock->getTerminator()))
461  InsertPt = splitBeforeCatchSwitch(CSI);
462  else
463  InsertPt = &*DefBlock->getFirstInsertionPt();
464  } else {
465  // For all other values, the spill is placed immediately after
466  // the definition.
467  assert(!isa<TerminatorInst>(E.def()) && "unexpected terminator");
468  InsertPt = cast<Instruction>(E.def())->getNextNode();
469  }
470 
471  Builder.SetInsertPoint(InsertPt);
472  auto *G = Builder.CreateConstInBoundsGEP2_32(
473  FrameTy, FramePtr, 0, Index,
474  CurrentValue->getName() + Twine(".spill.addr"));
475  Builder.CreateStore(CurrentValue, G);
476  }
477  }
478 
479  // If we have not seen the use block, generate a reload in it.
480  if (CurrentBlock != E.userBlock()) {
481  CurrentBlock = E.userBlock();
482  CurrentReload = CreateReload(&*CurrentBlock->getFirstInsertionPt());
483  }
484 
485  // If we have a single edge PHINode, remove it and replace it with a reload
486  // from the coroutine frame. (We already took care of multi edge PHINodes
487  // by rewriting them in the rewritePHIs function).
488  if (auto *PN = dyn_cast<PHINode>(E.user())) {
489  assert(PN->getNumIncomingValues() == 1 && "unexpected number of incoming "
490  "values in the PHINode");
491  PN->replaceAllUsesWith(CurrentReload);
492  PN->eraseFromParent();
493  continue;
494  }
495 
496  // Replace all uses of CurrentValue in the current instruction with reload.
497  E.user()->replaceUsesOfWith(CurrentValue, CurrentReload);
498  }
499 
500  BasicBlock *FramePtrBB = FramePtr->getParent();
501  Shape.AllocaSpillBlock =
502  FramePtrBB->splitBasicBlock(FramePtr->getNextNode(), "AllocaSpillBB");
504  "PostSpill");
505 
506  Builder.SetInsertPoint(&Shape.AllocaSpillBlock->front());
507  // If we found any allocas, replace all of their remaining uses with Geps.
508  for (auto &P : Allocas) {
509  auto *G =
510  Builder.CreateConstInBoundsGEP2_32(FrameTy, FramePtr, 0, P.second);
511  // We are not using ReplaceInstWithInst(P.first, cast<Instruction>(G)) here,
512  // as we are changing location of the instruction.
513  G->takeName(P.first);
514  P.first->replaceAllUsesWith(G);
515  P.first->eraseFromParent();
516  }
517  return FramePtr;
518 }
519 
520 // Sets the unwind edge of an instruction to a particular successor.
521 static void setUnwindEdgeTo(TerminatorInst *TI, BasicBlock *Succ) {
522  if (auto *II = dyn_cast<InvokeInst>(TI))
523  II->setUnwindDest(Succ);
524  else if (auto *CS = dyn_cast<CatchSwitchInst>(TI))
525  CS->setUnwindDest(Succ);
526  else if (auto *CR = dyn_cast<CleanupReturnInst>(TI))
527  CR->setUnwindDest(Succ);
528  else
529  llvm_unreachable("unexpected terminator instruction");
530 }
531 
532 // Replaces all uses of OldPred with the NewPred block in all PHINodes in a
533 // block.
534 static void updatePhiNodes(BasicBlock *DestBB, BasicBlock *OldPred,
535  BasicBlock *NewPred,
536  PHINode *LandingPadReplacement) {
537  unsigned BBIdx = 0;
538  for (BasicBlock::iterator I = DestBB->begin(); isa<PHINode>(I); ++I) {
539  PHINode *PN = cast<PHINode>(I);
540 
541  // We manually update the LandingPadReplacement PHINode and it is the last
542  // PHI Node. So, if we find it, we are done.
543  if (LandingPadReplacement == PN)
544  break;
545 
546  // Reuse the previous value of BBIdx if it lines up. In cases where we
547  // have multiple phi nodes with *lots* of predecessors, this is a speed
548  // win because we don't have to scan the PHI looking for TIBB. This
549  // happens because the BB list of PHI nodes are usually in the same
550  // order.
551  if (PN->getIncomingBlock(BBIdx) != OldPred)
552  BBIdx = PN->getBasicBlockIndex(OldPred);
553 
554  assert(BBIdx != (unsigned)-1 && "Invalid PHI Index!");
555  PN->setIncomingBlock(BBIdx, NewPred);
556  }
557 }
558 
559 // Uses SplitEdge unless the successor block is an EHPad, in which case do EH
560 // specific handling.
562  LandingPadInst *OriginalPad,
563  PHINode *LandingPadReplacement) {
564  auto *PadInst = Succ->getFirstNonPHI();
565  if (!LandingPadReplacement && !PadInst->isEHPad())
566  return SplitEdge(BB, Succ);
567 
568  auto *NewBB = BasicBlock::Create(BB->getContext(), "", BB->getParent(), Succ);
569  setUnwindEdgeTo(BB->getTerminator(), NewBB);
570  updatePhiNodes(Succ, BB, NewBB, LandingPadReplacement);
571 
572  if (LandingPadReplacement) {
573  auto *NewLP = OriginalPad->clone();
574  auto *Terminator = BranchInst::Create(Succ, NewBB);
575  NewLP->insertBefore(Terminator);
576  LandingPadReplacement->addIncoming(NewLP, NewBB);
577  return NewBB;
578  }
579  Value *ParentPad = nullptr;
580  if (auto *FuncletPad = dyn_cast<FuncletPadInst>(PadInst))
581  ParentPad = FuncletPad->getParentPad();
582  else if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(PadInst))
583  ParentPad = CatchSwitch->getParentPad();
584  else
585  llvm_unreachable("handling for other EHPads not implemented yet");
586 
587  auto *NewCleanupPad = CleanupPadInst::Create(ParentPad, {}, "", NewBB);
588  CleanupReturnInst::Create(NewCleanupPad, Succ, NewBB);
589  return NewBB;
590 }
591 
592 static void rewritePHIs(BasicBlock &BB) {
593  // For every incoming edge we will create a block holding all
594  // incoming values in a single PHI nodes.
595  //
596  // loop:
597  // %n.val = phi i32[%n, %entry], [%inc, %loop]
598  //
599  // It will create:
600  //
601  // loop.from.entry:
602  // %n.loop.pre = phi i32 [%n, %entry]
603  // br %label loop
604  // loop.from.loop:
605  // %inc.loop.pre = phi i32 [%inc, %loop]
606  // br %label loop
607  //
608  // After this rewrite, further analysis will ignore any phi nodes with more
609  // than one incoming edge.
610 
611  // TODO: Simplify PHINodes in the basic block to remove duplicate
612  // predecessors.
613 
614  LandingPadInst *LandingPad = nullptr;
615  PHINode *ReplPHI = nullptr;
616  if ((LandingPad = dyn_cast_or_null<LandingPadInst>(BB.getFirstNonPHI()))) {
617  // ehAwareSplitEdge will clone the LandingPad in all the edge blocks.
618  // We replace the original landing pad with a PHINode that will collect the
619  // results from all of them.
620  ReplPHI = PHINode::Create(LandingPad->getType(), 1, "", LandingPad);
621  ReplPHI->takeName(LandingPad);
622  LandingPad->replaceAllUsesWith(ReplPHI);
623  // We will erase the original landing pad at the end of this function after
624  // ehAwareSplitEdge cloned it in the transition blocks.
625  }
626 
628  for (BasicBlock *Pred : Preds) {
629  auto *IncomingBB = ehAwareSplitEdge(Pred, &BB, LandingPad, ReplPHI);
630  IncomingBB->setName(BB.getName() + Twine(".from.") + Pred->getName());
631  auto *PN = cast<PHINode>(&BB.front());
632  do {
633  int Index = PN->getBasicBlockIndex(IncomingBB);
634  Value *V = PN->getIncomingValue(Index);
635  PHINode *InputV = PHINode::Create(
636  V->getType(), 1, V->getName() + Twine(".") + BB.getName(),
637  &IncomingBB->front());
638  InputV->addIncoming(V, Pred);
639  PN->setIncomingValue(Index, InputV);
640  PN = dyn_cast<PHINode>(PN->getNextNode());
641  } while (PN != ReplPHI); // ReplPHI is either null or the PHI that replaced
642  // the landing pad.
643  }
644 
645  if (LandingPad) {
646  // Calls to ehAwareSplitEdge function cloned the original lading pad.
647  // No longer need it.
648  LandingPad->eraseFromParent();
649  }
650 }
651 
652 static void rewritePHIs(Function &F) {
654 
655  for (BasicBlock &BB : F)
656  if (auto *PN = dyn_cast<PHINode>(&BB.front()))
657  if (PN->getNumIncomingValues() > 1)
658  WorkList.push_back(&BB);
659 
660  for (BasicBlock *BB : WorkList)
661  rewritePHIs(*BB);
662 }
663 
664 // Check for instructions that we can recreate on resume as opposed to spill
665 // the result into a coroutine frame.
666 static bool materializable(Instruction &V) {
667  return isa<CastInst>(&V) || isa<GetElementPtrInst>(&V) ||
668  isa<BinaryOperator>(&V) || isa<CmpInst>(&V) || isa<SelectInst>(&V);
669 }
670 
671 // Check for structural coroutine intrinsics that should not be spilled into
672 // the coroutine frame.
674  return isa<CoroIdInst>(&I) || isa<CoroSaveInst>(&I) ||
675  isa<CoroSuspendInst>(&I);
676 }
677 
678 // For every use of the value that is across suspend point, recreate that value
679 // after a suspend point.
681  SpillInfo const &Spills) {
682  BasicBlock *CurrentBlock = nullptr;
683  Instruction *CurrentMaterialization = nullptr;
684  Instruction *CurrentDef = nullptr;
685 
686  for (auto const &E : Spills) {
687  // If it is a new definition, update CurrentXXX variables.
688  if (CurrentDef != E.def()) {
689  CurrentDef = cast<Instruction>(E.def());
690  CurrentBlock = nullptr;
691  CurrentMaterialization = nullptr;
692  }
693 
694  // If we have not seen this block, materialize the value.
695  if (CurrentBlock != E.userBlock()) {
696  CurrentBlock = E.userBlock();
697  CurrentMaterialization = cast<Instruction>(CurrentDef)->clone();
698  CurrentMaterialization->setName(CurrentDef->getName());
699  CurrentMaterialization->insertBefore(
700  &*CurrentBlock->getFirstInsertionPt());
701  }
702 
703  if (auto *PN = dyn_cast<PHINode>(E.user())) {
704  assert(PN->getNumIncomingValues() == 1 && "unexpected number of incoming "
705  "values in the PHINode");
706  PN->replaceAllUsesWith(CurrentMaterialization);
707  PN->eraseFromParent();
708  continue;
709  }
710 
711  // Replace all uses of CurrentDef in the current instruction with the
712  // CurrentMaterialization for the block.
713  E.user()->replaceUsesOfWith(CurrentDef, CurrentMaterialization);
714  }
715 }
716 
717 // Move early uses of spilled variable after CoroBegin.
718 // For example, if a parameter had address taken, we may end up with the code
719 // like:
720 // define @f(i32 %n) {
721 // %n.addr = alloca i32
722 // store %n, %n.addr
723 // ...
724 // call @coro.begin
725 // we need to move the store after coro.begin
726 static void moveSpillUsesAfterCoroBegin(Function &F, SpillInfo const &Spills,
727  CoroBeginInst *CoroBegin) {
728  DominatorTree DT(F);
729  SmallVector<Instruction *, 8> NeedsMoving;
730 
731  Value *CurrentValue = nullptr;
732 
733  for (auto const &E : Spills) {
734  if (CurrentValue == E.def())
735  continue;
736 
737  CurrentValue = E.def();
738 
739  for (User *U : CurrentValue->users()) {
740  Instruction *I = cast<Instruction>(U);
741  if (!DT.dominates(CoroBegin, I)) {
742  // TODO: Make this more robust. Currently if we run into a situation
743  // where simple instruction move won't work we panic and
744  // report_fatal_error.
745  for (User *UI : I->users()) {
746  if (!DT.dominates(CoroBegin, cast<Instruction>(UI)))
747  report_fatal_error("cannot move instruction since its users are not"
748  " dominated by CoroBegin");
749  }
750 
751  DEBUG(dbgs() << "will move: " << *I << "\n");
752  NeedsMoving.push_back(I);
753  }
754  }
755  }
756 
757  Instruction *InsertPt = CoroBegin->getNextNode();
758  for (Instruction *I : NeedsMoving)
759  I->moveBefore(InsertPt);
760 }
761 
762 // Splits the block at a particular instruction unless it is the first
763 // instruction in the block with a single predecessor.
765  auto *BB = I->getParent();
766  if (&BB->front() == I) {
767  if (BB->getSinglePredecessor()) {
768  BB->setName(Name);
769  return BB;
770  }
771  }
772  return BB->splitBasicBlock(I, Name);
773 }
774 
775 // Split above and below a particular instruction so that it
776 // will be all alone by itself in a block.
777 static void splitAround(Instruction *I, const Twine &Name) {
778  splitBlockIfNotFirst(I, Name);
779  splitBlockIfNotFirst(I->getNextNode(), "After" + Name);
780 }
781 
782 void coro::buildCoroutineFrame(Function &F, Shape &Shape) {
783  // Lower coro.dbg.declare to coro.dbg.value, since we are going to rewrite
784  // access to local variables.
785  LowerDbgDeclare(F);
786 
787  Shape.PromiseAlloca = Shape.CoroBegin->getId()->getPromise();
788  if (Shape.PromiseAlloca) {
789  Shape.CoroBegin->getId()->clearPromise();
790  }
791 
792  // Make sure that all coro.save, coro.suspend and the fallthrough coro.end
793  // intrinsics are in their own blocks to simplify the logic of building up
794  // SuspendCrossing data.
795  for (CoroSuspendInst *CSI : Shape.CoroSuspends) {
796  splitAround(CSI->getCoroSave(), "CoroSave");
797  splitAround(CSI, "CoroSuspend");
798  }
799 
800  // Put CoroEnds into their own blocks.
801  for (CoroEndInst *CE : Shape.CoroEnds)
802  splitAround(CE, "CoroEnd");
803 
804  // Transforms multi-edge PHI Nodes, so that any value feeding into a PHI will
805  // never has its definition separated from the PHI by the suspend point.
806  rewritePHIs(F);
807 
808  // Build suspend crossing info.
809  SuspendCrossingInfo Checker(F, Shape);
810 
811  IRBuilder<> Builder(F.getContext());
812  SpillInfo Spills;
813 
814  for (int Repeat = 0; Repeat < 4; ++Repeat) {
815  // See if there are materializable instructions across suspend points.
816  for (Instruction &I : instructions(F))
817  if (materializable(I))
818  for (User *U : I.users())
819  if (Checker.isDefinitionAcrossSuspend(I, U))
820  Spills.emplace_back(&I, U);
821 
822  if (Spills.empty())
823  break;
824 
825  // Rewrite materializable instructions to be materialized at the use point.
826  DEBUG(dump("Materializations", Spills));
827  rewriteMaterializableInstructions(Builder, Spills);
828  Spills.clear();
829  }
830 
831  // Collect the spills for arguments and other not-materializable values.
832  for (Argument &A : F.args())
833  for (User *U : A.users())
834  if (Checker.isDefinitionAcrossSuspend(A, U))
835  Spills.emplace_back(&A, U);
836 
837  for (Instruction &I : instructions(F)) {
838  // Values returned from coroutine structure intrinsics should not be part
839  // of the Coroutine Frame.
840  if (isCoroutineStructureIntrinsic(I) || &I == Shape.CoroBegin)
841  continue;
842  // The Coroutine Promise always included into coroutine frame, no need to
843  // check for suspend crossing.
844  if (Shape.PromiseAlloca == &I)
845  continue;
846 
847  for (User *U : I.users())
848  if (Checker.isDefinitionAcrossSuspend(I, U)) {
849  // We cannot spill a token.
850  if (I.getType()->isTokenTy())
852  "token definition is separated from the use by a suspend point");
853  Spills.emplace_back(&I, U);
854  }
855  }
856  DEBUG(dump("Spills", Spills));
857  moveSpillUsesAfterCoroBegin(F, Spills, Shape.CoroBegin);
858  Shape.FrameTy = buildFrameType(F, Shape, Spills);
859  Shape.FramePtr = insertSpills(Spills, Shape);
860 }
uint64_t CallInst * C
static Instruction * splitBeforeCatchSwitch(CatchSwitchInst *CatchSwitch)
Definition: CoroFrame.cpp:357
SymbolTableList< Instruction >::iterator eraseFromParent()
This method unlinks &#39;this&#39; from the containing basic block and deletes it.
Definition: Instruction.cpp:69
static IntegerType * getInt1Ty(LLVMContext &C)
Definition: Type.cpp:173
Instruction * FramePtr
Definition: CoroInternal.h:83
void addIncoming(Value *V, BasicBlock *BB)
Add an incoming value to the end of the PHI list.
GCNRegPressure max(const GCNRegPressure &P1, const GCNRegPressure &P2)
This class represents an incoming formal argument to a Function.
Definition: Argument.h:30
CoroBeginInst * CoroBegin
Definition: CoroInternal.h:68
NodeTy * getNextNode()
Get the next node, or nullptr for the list tail.
Definition: ilist_node.h:289
LLVM_ATTRIBUTE_NORETURN void report_fatal_error(Error Err, bool gen_crash_diag=true)
Report a serious error, calling any installed error handler.
Definition: Error.cpp:115
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
#define LLVM_DUMP_METHOD
Mark debug helper function definitions like dump() that should not be stripped from debug builds...
Definition: Compiler.h:449
LLVM_ATTRIBUTE_ALWAYS_INLINE size_type size() const
Definition: SmallVector.h:136
static void updatePhiNodes(BasicBlock *DestBB, BasicBlock *OldPred, BasicBlock *NewPred, PHINode *LandingPadReplacement)
Definition: CoroFrame.cpp:534
static void rewritePHIs(BasicBlock &BB)
Definition: CoroFrame.cpp:592
static void dump(StringRef Title, SpillInfo const &Spills)
Definition: CoroFrame.cpp:283
F(f)
LLVMContext & getContext() const
Get the context in which this basic block lives.
Definition: BasicBlock.cpp:33
iterator begin()
Instruction iterator methods.
Definition: BasicBlock.h:252
void dump() const
Support for debugging, callable in GDB: V->dump()
Definition: AsmWriter.cpp:3641
int getBasicBlockIndex(const BasicBlock *BB) const
Return the first index of the specified basic block in the value list for this PHI.
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
PointerType * getType() const
Overload to return most specific pointer type.
Definition: Instructions.h:97
Class to represent struct types.
Definition: DerivedTypes.h:201
static bool materializable(Instruction &V)
Definition: CoroFrame.cpp:666
PointerType * getPointerTo(unsigned AddrSpace=0) const
Return a pointer to the current type.
Definition: Type.cpp:639
This represents the llvm.coro.suspend instruction.
Definition: CoroInstr.h:266
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:668
void setName(const Twine &Name)
Change the name of the value.
Definition: Value.cpp:286
AllocaInst * getPromise() const
Definition: CoroInstr.h:101
Instruction * clone() const
Create a copy of &#39;this&#39; instruction that is identical in all ways except the following: ...
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:245
auto lower_bound(R &&Range, ForwardIt I) -> decltype(adl_begin(Range))
Provide wrappers to std::lower_bound which take ranges instead of having to pass begin/end explicitly...
Definition: STLExtras.h:904
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:430
Value * getParentPad() const
SmallVector< CoroSuspendInst *, 4 > CoroSuspends
Definition: CoroInternal.h:71
void setBody(ArrayRef< Type *> Elements, bool isPacked=false)
Specify a body for an opaque identified type.
Definition: Type.cpp:356
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:292
Concrete subclass of DominatorTreeBase that is used to compute a normal dominator tree...
Definition: Dominators.h:140
Class to represent pointers.
Definition: DerivedTypes.h:467
const BasicBlock & getEntryBlock() const
Definition: Function.h:572
#define P(N)
The landingpad instruction holds all of the information necessary to generate correct exception handl...
const Instruction * getFirstNonPHI() const
Returns a pointer to the first instruction in this block that is not a PHINode instruction.
Definition: BasicBlock.cpp:171
static GCRegistry::Add< OcamlGC > B("ocaml", "ocaml 3.10-compatible GC")
void dump(const SparseBitVector< ElementSize > &LHS, raw_ostream &out)
Subclasses of this class are all able to terminate a basic block.
Definition: InstrTypes.h:54
static void moveSpillUsesAfterCoroBegin(Function &F, SpillInfo const &Spills, CoroBeginInst *CoroBegin)
Definition: CoroFrame.cpp:726
const_iterator getFirstInsertionPt() const
Returns an iterator to the first instruction in this block that is suitable for inserting a non-PHI i...
Definition: BasicBlock.cpp:200
void insertBefore(Instruction *InsertPos)
Insert an unlinked instruction into a basic block immediately before the specified instruction...
Definition: Instruction.cpp:75
LLVM Basic Block Representation.
Definition: BasicBlock.h:59
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
This is an important class for using LLVM in a threaded context.
Definition: LLVMContext.h:69
static GCRegistry::Add< CoreCLRGC > E("coreclr", "CoreCLR-compatible GC")
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator begin()
Definition: SmallVector.h:116
const Instruction & front() const
Definition: BasicBlock.h:264
Interval::pred_iterator pred_begin(Interval *I)
pred_begin/pred_end - define methods so that Intervals may be used just like BasicBlocks can with the...
Definition: Interval.h:113
static Type * getVoidTy(LLVMContext &C)
Definition: Type.cpp:161
This represents the llvm.coro.end instruction.
Definition: CoroInstr.h:303
static const unsigned End
static FunctionType * get(Type *Result, ArrayRef< Type *> Params, bool isVarArg)
This static method is the primary way of constructing a FunctionType.
Definition: Type.cpp:297
Interval::pred_iterator pred_end(Interval *I)
Definition: Interval.h:116
static BasicBlock * Create(LLVMContext &Context, const Twine &Name="", Function *Parent=nullptr, BasicBlock *InsertBefore=nullptr)
Creates a new BasicBlock.
Definition: BasicBlock.h:101
LLVMContext & getContext() const
getContext - Return a reference to the LLVMContext associated with this function. ...
Definition: Function.cpp:194
bool LowerDbgDeclare(Function &F)
Lowers llvm.dbg.declare intrinsics into appropriate set of llvm.dbg.value intrinsics.
Definition: Local.cpp:1224
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
static bool isCoroutineStructureIntrinsic(Instruction &I)
Definition: CoroFrame.cpp:673
Iterator for intrusive lists based on ilist_node.
StructType * FrameTy
Definition: CoroInternal.h:82
void setIncomingBlock(unsigned i, BasicBlock *BB)
static CleanupPadInst * Create(Value *ParentPad, ArrayRef< Value *> Args=None, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:864
bool dominates(const Instruction *Def, const Use &U) const
Return true if Def dominates a use in User.
Definition: Dominators.cpp:239
const DataFlowGraph & G
Definition: RDFGraph.cpp:211
static IntegerType * getIntNTy(LLVMContext &C, unsigned N)
Definition: Type.cpp:180
void buildCoroutineFrame(Function &F, Shape &Shape)
Definition: CoroFrame.cpp:782
static BranchInst * Create(BasicBlock *IfTrue, Instruction *InsertBefore=nullptr)
static PHINode * Create(Type *Ty, unsigned NumReservedValues, const Twine &NameStr="", Instruction *InsertBefore=nullptr)
Constructors - NumReservedValues is a hint for the number of incoming edges that this phi node will h...
unsigned Log2_64_Ceil(uint64_t Value)
Return the ceil log base 2 of the specified value, 64 if the value is zero.
Definition: MathExtras.h:550
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:132
This class represents the llvm.coro.begin instruction.
Definition: CoroInstr.h:215
A range adaptor for a pair of iterators.
iterator_range< user_iterator > users()
Definition: Value.h:401
static BasicBlock * splitBlockIfNotFirst(Instruction *I, const Twine &Name)
Definition: CoroFrame.cpp:764
void clearPromise()
Definition: CoroInstr.h:108
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator end()
Definition: SmallVector.h:120
static void rewriteMaterializableInstructions(IRBuilder<> &IRB, SpillInfo const &Spills)
Definition: CoroFrame.cpp:680
const Function * getParent() const
Definition: Argument.h:42
void emplace_back(ArgTypes &&... Args)
Definition: SmallVector.h:656
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:220
BasicBlock * getIncomingBlock(unsigned i) const
Return incoming basic block number i.
const Function * getParent() const
Return the enclosing method, or null if none.
Definition: BasicBlock.h:108
static Instruction * insertSpills(SpillInfo &Spills, coro::Shape &Shape)
Definition: CoroFrame.cpp:391
#define I(x, y, z)
Definition: MD5.cpp:58
#define N
LLVM_NODISCARD std::enable_if<!is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:323
size_type size() const
size - Returns the number of bits in this bitvector.
Definition: BitVector.h:170
BasicBlock * splitBasicBlock(iterator I, const Twine &BBName="")
Split the basic block into two basic blocks at the specified instruction.
Definition: BasicBlock.cpp:382
CoroIdInst * getId() const
Definition: CoroInstr.h:219
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
SmallVector< CoroEndInst *, 4 > CoroEnds
Definition: CoroInternal.h:69
LLVM_NODISCARD char front() const
front - Get the first character in the string.
Definition: StringRef.h:142
AllocaInst * PromiseAlloca
Definition: CoroInternal.h:86
static BasicBlock * ehAwareSplitEdge(BasicBlock *BB, BasicBlock *Succ, LandingPadInst *OriginalPad, PHINode *LandingPadReplacement)
Definition: CoroFrame.cpp:561
static StructType * buildFrameType(Function &F, coro::Shape &Shape, SpillInfo &Spills)
Definition: CoroFrame.cpp:305
LLVM Value Representation.
Definition: Value.h:73
succ_range successors(BasicBlock *BB)
Definition: CFG.h:143
static StructType * create(LLVMContext &Context, StringRef Name)
This creates an identified struct.
Definition: Type.cpp:424
static CleanupReturnInst * Create(Value *CleanupPad, BasicBlock *UnwindBB=nullptr, Instruction *InsertBefore=nullptr)
static const Function * getParent(const Value *V)
static const unsigned FramePtr
#define DEBUG(X)
Definition: Debug.h:118
BasicBlock * SplitEdge(BasicBlock *From, BasicBlock *To, DominatorTree *DT=nullptr, LoopInfo *LI=nullptr)
Split the edge connecting specified block.
bool isEHPad() const
Return true if the instruction is a variety of EH-block.
Definition: Instruction.h:538
StringRef - Represent a constant reference to a string, i.e.
Definition: StringRef.h:49
inst_range instructions(Function *F)
Definition: InstIterator.h:134
void sort(Policy policy, RandomAccessIterator Start, RandomAccessIterator End, const Comparator &Comp=Comparator())
Definition: Parallel.h:199
BasicBlock * AllocaSpillBlock
Definition: CoroInternal.h:84
const TerminatorInst * getTerminator() const LLVM_READONLY
Returns the terminator instruction if the block is well formed or null if the block is not well forme...
Definition: BasicBlock.cpp:120
static void setUnwindEdgeTo(TerminatorInst *TI, BasicBlock *Succ)
Definition: CoroFrame.cpp:521
static void splitAround(Instruction *I, const Twine &Name)
Definition: CoroFrame.cpp:777
CoroSaveInst * getCoroSave() const
Definition: CoroInstr.h:270
Type * getElementType() const
Definition: DerivedTypes.h:486
iterator_range< arg_iterator > args()
Definition: Function.h:621
A wrapper class for inspecting calls to intrinsic functions.
Definition: IntrinsicInst.h:44
const BasicBlock * getParent() const
Definition: Instruction.h:66