xref: /freebsd/contrib/llvm-project/llvm/lib/Transforms/Scalar/CallSiteSplitting.cpp (revision ec0ea6efa1ad229d75c394c1a9b9cac33af2b1d3)
1 //===- CallSiteSplitting.cpp ----------------------------------------------===//
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 file implements a transformation that tries to split a call-site to pass
10 // more constrained arguments if its argument is predicated in the control flow
11 // so that we can expose better context to the later passes (e.g, inliner, jump
12 // threading, or IPA-CP based function cloning, etc.).
13 // As of now we support two cases :
14 //
15 // 1) Try to a split call-site with constrained arguments, if any constraints
16 // on any argument can be found by following the single predecessors of the
17 // all site's predecessors. Currently this pass only handles call-sites with 2
18 // predecessors. For example, in the code below, we try to split the call-site
19 // since we can predicate the argument(ptr) based on the OR condition.
20 //
21 // Split from :
22 //   if (!ptr || c)
23 //     callee(ptr);
24 // to :
25 //   if (!ptr)
26 //     callee(null)         // set the known constant value
27 //   else if (c)
28 //     callee(nonnull ptr)  // set non-null attribute in the argument
29 //
30 // 2) We can also split a call-site based on constant incoming values of a PHI
31 // For example,
32 // from :
33 //   Header:
34 //    %c = icmp eq i32 %i1, %i2
35 //    br i1 %c, label %Tail, label %TBB
36 //   TBB:
37 //    br label Tail%
38 //   Tail:
39 //    %p = phi i32 [ 0, %Header], [ 1, %TBB]
40 //    call void @bar(i32 %p)
41 // to
42 //   Header:
43 //    %c = icmp eq i32 %i1, %i2
44 //    br i1 %c, label %Tail-split0, label %TBB
45 //   TBB:
46 //    br label %Tail-split1
47 //   Tail-split0:
48 //    call void @bar(i32 0)
49 //    br label %Tail
50 //   Tail-split1:
51 //    call void @bar(i32 1)
52 //    br label %Tail
53 //   Tail:
54 //    %p = phi i32 [ 0, %Tail-split0 ], [ 1, %Tail-split1 ]
55 //
56 //===----------------------------------------------------------------------===//
57 
58 #include "llvm/Transforms/Scalar/CallSiteSplitting.h"
59 #include "llvm/ADT/Statistic.h"
60 #include "llvm/Analysis/TargetLibraryInfo.h"
61 #include "llvm/Analysis/TargetTransformInfo.h"
62 #include "llvm/IR/IntrinsicInst.h"
63 #include "llvm/IR/PatternMatch.h"
64 #include "llvm/InitializePasses.h"
65 #include "llvm/Support/CommandLine.h"
66 #include "llvm/Support/Debug.h"
67 #include "llvm/Transforms/Scalar.h"
68 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
69 #include "llvm/Transforms/Utils/Cloning.h"
70 #include "llvm/Transforms/Utils/Local.h"
71 
72 using namespace llvm;
73 using namespace PatternMatch;
74 
75 #define DEBUG_TYPE "callsite-splitting"
76 
77 STATISTIC(NumCallSiteSplit, "Number of call-site split");
78 
79 /// Only allow instructions before a call, if their CodeSize cost is below
80 /// DuplicationThreshold. Those instructions need to be duplicated in all
81 /// split blocks.
82 static cl::opt<unsigned>
83     DuplicationThreshold("callsite-splitting-duplication-threshold", cl::Hidden,
84                          cl::desc("Only allow instructions before a call, if "
85                                   "their cost is below DuplicationThreshold"),
86                          cl::init(5));
87 
88 static void addNonNullAttribute(CallBase &CB, Value *Op) {
89   unsigned ArgNo = 0;
90   for (auto &I : CB.args()) {
91     if (&*I == Op)
92       CB.addParamAttr(ArgNo, Attribute::NonNull);
93     ++ArgNo;
94   }
95 }
96 
97 static void setConstantInArgument(CallBase &CB, Value *Op,
98                                   Constant *ConstValue) {
99   unsigned ArgNo = 0;
100   for (auto &I : CB.args()) {
101     if (&*I == Op) {
102       // It is possible we have already added the non-null attribute to the
103       // parameter by using an earlier constraining condition.
104       CB.removeParamAttr(ArgNo, Attribute::NonNull);
105       CB.setArgOperand(ArgNo, ConstValue);
106     }
107     ++ArgNo;
108   }
109 }
110 
111 static bool isCondRelevantToAnyCallArgument(ICmpInst *Cmp, CallBase &CB) {
112   assert(isa<Constant>(Cmp->getOperand(1)) && "Expected a constant operand.");
113   Value *Op0 = Cmp->getOperand(0);
114   unsigned ArgNo = 0;
115   for (auto I = CB.arg_begin(), E = CB.arg_end(); I != E; ++I, ++ArgNo) {
116     // Don't consider constant or arguments that are already known non-null.
117     if (isa<Constant>(*I) || CB.paramHasAttr(ArgNo, Attribute::NonNull))
118       continue;
119 
120     if (*I == Op0)
121       return true;
122   }
123   return false;
124 }
125 
126 typedef std::pair<ICmpInst *, unsigned> ConditionTy;
127 typedef SmallVector<ConditionTy, 2> ConditionsTy;
128 
129 /// If From has a conditional jump to To, add the condition to Conditions,
130 /// if it is relevant to any argument at CB.
131 static void recordCondition(CallBase &CB, BasicBlock *From, BasicBlock *To,
132                             ConditionsTy &Conditions) {
133   auto *BI = dyn_cast<BranchInst>(From->getTerminator());
134   if (!BI || !BI->isConditional())
135     return;
136 
137   CmpInst::Predicate Pred;
138   Value *Cond = BI->getCondition();
139   if (!match(Cond, m_ICmp(Pred, m_Value(), m_Constant())))
140     return;
141 
142   ICmpInst *Cmp = cast<ICmpInst>(Cond);
143   if (Pred == ICmpInst::ICMP_EQ || Pred == ICmpInst::ICMP_NE)
144     if (isCondRelevantToAnyCallArgument(Cmp, CB))
145       Conditions.push_back({Cmp, From->getTerminator()->getSuccessor(0) == To
146                                      ? Pred
147                                      : Cmp->getInversePredicate()});
148 }
149 
150 /// Record ICmp conditions relevant to any argument in CB following Pred's
151 /// single predecessors. If there are conflicting conditions along a path, like
152 /// x == 1 and x == 0, the first condition will be used. We stop once we reach
153 /// an edge to StopAt.
154 static void recordConditions(CallBase &CB, BasicBlock *Pred,
155                              ConditionsTy &Conditions, BasicBlock *StopAt) {
156   BasicBlock *From = Pred;
157   BasicBlock *To = Pred;
158   SmallPtrSet<BasicBlock *, 4> Visited;
159   while (To != StopAt && !Visited.count(From->getSinglePredecessor()) &&
160          (From = From->getSinglePredecessor())) {
161     recordCondition(CB, From, To, Conditions);
162     Visited.insert(From);
163     To = From;
164   }
165 }
166 
167 static void addConditions(CallBase &CB, const ConditionsTy &Conditions) {
168   for (auto &Cond : Conditions) {
169     Value *Arg = Cond.first->getOperand(0);
170     Constant *ConstVal = cast<Constant>(Cond.first->getOperand(1));
171     if (Cond.second == ICmpInst::ICMP_EQ)
172       setConstantInArgument(CB, Arg, ConstVal);
173     else if (ConstVal->getType()->isPointerTy() && ConstVal->isNullValue()) {
174       assert(Cond.second == ICmpInst::ICMP_NE);
175       addNonNullAttribute(CB, Arg);
176     }
177   }
178 }
179 
180 static SmallVector<BasicBlock *, 2> getTwoPredecessors(BasicBlock *BB) {
181   SmallVector<BasicBlock *, 2> Preds(predecessors((BB)));
182   assert(Preds.size() == 2 && "Expected exactly 2 predecessors!");
183   return Preds;
184 }
185 
186 static bool canSplitCallSite(CallBase &CB, TargetTransformInfo &TTI) {
187   if (CB.isConvergent() || CB.cannotDuplicate())
188     return false;
189 
190   // FIXME: As of now we handle only CallInst. InvokeInst could be handled
191   // without too much effort.
192   if (!isa<CallInst>(CB))
193     return false;
194 
195   BasicBlock *CallSiteBB = CB.getParent();
196   // Need 2 predecessors and cannot split an edge from an IndirectBrInst.
197   SmallVector<BasicBlock *, 2> Preds(predecessors(CallSiteBB));
198   if (Preds.size() != 2 || isa<IndirectBrInst>(Preds[0]->getTerminator()) ||
199       isa<IndirectBrInst>(Preds[1]->getTerminator()))
200     return false;
201 
202   // BasicBlock::canSplitPredecessors is more aggressive, so checking for
203   // BasicBlock::isEHPad as well.
204   if (!CallSiteBB->canSplitPredecessors() || CallSiteBB->isEHPad())
205     return false;
206 
207   // Allow splitting a call-site only when the CodeSize cost of the
208   // instructions before the call is less then DuplicationThreshold. The
209   // instructions before the call will be duplicated in the split blocks and
210   // corresponding uses will be updated.
211   InstructionCost Cost = 0;
212   for (auto &InstBeforeCall :
213        llvm::make_range(CallSiteBB->begin(), CB.getIterator())) {
214     Cost += TTI.getInstructionCost(&InstBeforeCall,
215                                    TargetTransformInfo::TCK_CodeSize);
216     if (Cost >= DuplicationThreshold)
217       return false;
218   }
219 
220   return true;
221 }
222 
223 static Instruction *cloneInstForMustTail(Instruction *I, Instruction *Before,
224                                          Value *V) {
225   Instruction *Copy = I->clone();
226   Copy->setName(I->getName());
227   Copy->insertBefore(Before);
228   if (V)
229     Copy->setOperand(0, V);
230   return Copy;
231 }
232 
233 /// Copy mandatory `musttail` return sequence that follows original `CI`, and
234 /// link it up to `NewCI` value instead:
235 ///
236 ///   * (optional) `bitcast NewCI to ...`
237 ///   * `ret bitcast or NewCI`
238 ///
239 /// Insert this sequence right before `SplitBB`'s terminator, which will be
240 /// cleaned up later in `splitCallSite` below.
241 static void copyMustTailReturn(BasicBlock *SplitBB, Instruction *CI,
242                                Instruction *NewCI) {
243   bool IsVoid = SplitBB->getParent()->getReturnType()->isVoidTy();
244   auto II = std::next(CI->getIterator());
245 
246   BitCastInst* BCI = dyn_cast<BitCastInst>(&*II);
247   if (BCI)
248     ++II;
249 
250   ReturnInst* RI = dyn_cast<ReturnInst>(&*II);
251   assert(RI && "`musttail` call must be followed by `ret` instruction");
252 
253   Instruction *TI = SplitBB->getTerminator();
254   Value *V = NewCI;
255   if (BCI)
256     V = cloneInstForMustTail(BCI, TI, V);
257   cloneInstForMustTail(RI, TI, IsVoid ? nullptr : V);
258 
259   // FIXME: remove TI here, `DuplicateInstructionsInSplitBetween` has a bug
260   // that prevents doing this now.
261 }
262 
263 /// For each (predecessor, conditions from predecessors) pair, it will split the
264 /// basic block containing the call site, hook it up to the predecessor and
265 /// replace the call instruction with new call instructions, which contain
266 /// constraints based on the conditions from their predecessors.
267 /// For example, in the IR below with an OR condition, the call-site can
268 /// be split. In this case, Preds for Tail is [(Header, a == null),
269 /// (TBB, a != null, b == null)]. Tail is replaced by 2 split blocks, containing
270 /// CallInst1, which has constraints based on the conditions from Head and
271 /// CallInst2, which has constraints based on the conditions coming from TBB.
272 ///
273 /// From :
274 ///
275 ///   Header:
276 ///     %c = icmp eq i32* %a, null
277 ///     br i1 %c %Tail, %TBB
278 ///   TBB:
279 ///     %c2 = icmp eq i32* %b, null
280 ///     br i1 %c %Tail, %End
281 ///   Tail:
282 ///     %ca = call i1  @callee (i32* %a, i32* %b)
283 ///
284 ///  to :
285 ///
286 ///   Header:                          // PredBB1 is Header
287 ///     %c = icmp eq i32* %a, null
288 ///     br i1 %c %Tail-split1, %TBB
289 ///   TBB:                             // PredBB2 is TBB
290 ///     %c2 = icmp eq i32* %b, null
291 ///     br i1 %c %Tail-split2, %End
292 ///   Tail-split1:
293 ///     %ca1 = call @callee (i32* null, i32* %b)         // CallInst1
294 ///    br %Tail
295 ///   Tail-split2:
296 ///     %ca2 = call @callee (i32* nonnull %a, i32* null) // CallInst2
297 ///    br %Tail
298 ///   Tail:
299 ///    %p = phi i1 [%ca1, %Tail-split1],[%ca2, %Tail-split2]
300 ///
301 /// Note that in case any arguments at the call-site are constrained by its
302 /// predecessors, new call-sites with more constrained arguments will be
303 /// created in createCallSitesOnPredicatedArgument().
304 static void splitCallSite(
305     CallBase &CB,
306     const SmallVectorImpl<std::pair<BasicBlock *, ConditionsTy>> &Preds,
307     DomTreeUpdater &DTU) {
308   BasicBlock *TailBB = CB.getParent();
309   bool IsMustTailCall = CB.isMustTailCall();
310 
311   PHINode *CallPN = nullptr;
312 
313   // `musttail` calls must be followed by optional `bitcast`, and `ret`. The
314   // split blocks will be terminated right after that so there're no users for
315   // this phi in a `TailBB`.
316   if (!IsMustTailCall && !CB.use_empty()) {
317     CallPN = PHINode::Create(CB.getType(), Preds.size(), "phi.call");
318     CallPN->setDebugLoc(CB.getDebugLoc());
319   }
320 
321   LLVM_DEBUG(dbgs() << "split call-site : " << CB << " into \n");
322 
323   assert(Preds.size() == 2 && "The ValueToValueMaps array has size 2.");
324   // ValueToValueMapTy is neither copy nor moveable, so we use a simple array
325   // here.
326   ValueToValueMapTy ValueToValueMaps[2];
327   for (unsigned i = 0; i < Preds.size(); i++) {
328     BasicBlock *PredBB = Preds[i].first;
329     BasicBlock *SplitBlock = DuplicateInstructionsInSplitBetween(
330         TailBB, PredBB, &*std::next(CB.getIterator()), ValueToValueMaps[i],
331         DTU);
332     assert(SplitBlock && "Unexpected new basic block split.");
333 
334     auto *NewCI =
335         cast<CallBase>(&*std::prev(SplitBlock->getTerminator()->getIterator()));
336     addConditions(*NewCI, Preds[i].second);
337 
338     // Handle PHIs used as arguments in the call-site.
339     for (PHINode &PN : TailBB->phis()) {
340       unsigned ArgNo = 0;
341       for (auto &CI : CB.args()) {
342         if (&*CI == &PN) {
343           NewCI->setArgOperand(ArgNo, PN.getIncomingValueForBlock(SplitBlock));
344         }
345         ++ArgNo;
346       }
347     }
348     LLVM_DEBUG(dbgs() << "    " << *NewCI << " in " << SplitBlock->getName()
349                       << "\n");
350     if (CallPN)
351       CallPN->addIncoming(NewCI, SplitBlock);
352 
353     // Clone and place bitcast and return instructions before `TI`
354     if (IsMustTailCall)
355       copyMustTailReturn(SplitBlock, &CB, NewCI);
356   }
357 
358   NumCallSiteSplit++;
359 
360   // FIXME: remove TI in `copyMustTailReturn`
361   if (IsMustTailCall) {
362     // Remove superfluous `br` terminators from the end of the Split blocks
363     // NOTE: Removing terminator removes the SplitBlock from the TailBB's
364     // predecessors. Therefore we must get complete list of Splits before
365     // attempting removal.
366     SmallVector<BasicBlock *, 2> Splits(predecessors((TailBB)));
367     assert(Splits.size() == 2 && "Expected exactly 2 splits!");
368     for (unsigned i = 0; i < Splits.size(); i++) {
369       Splits[i]->getTerminator()->eraseFromParent();
370       DTU.applyUpdatesPermissive({{DominatorTree::Delete, Splits[i], TailBB}});
371     }
372 
373     // Erase the tail block once done with musttail patching
374     DTU.deleteBB(TailBB);
375     return;
376   }
377 
378   auto *OriginalBegin = &*TailBB->begin();
379   // Replace users of the original call with a PHI mering call-sites split.
380   if (CallPN) {
381     CallPN->insertBefore(OriginalBegin);
382     CB.replaceAllUsesWith(CallPN);
383   }
384 
385   // Remove instructions moved to split blocks from TailBB, from the duplicated
386   // call instruction to the beginning of the basic block. If an instruction
387   // has any uses, add a new PHI node to combine the values coming from the
388   // split blocks. The new PHI nodes are placed before the first original
389   // instruction, so we do not end up deleting them. By using reverse-order, we
390   // do not introduce unnecessary PHI nodes for def-use chains from the call
391   // instruction to the beginning of the block.
392   auto I = CB.getReverseIterator();
393   while (I != TailBB->rend()) {
394     Instruction *CurrentI = &*I++;
395     if (!CurrentI->use_empty()) {
396       // If an existing PHI has users after the call, there is no need to create
397       // a new one.
398       if (isa<PHINode>(CurrentI))
399         continue;
400       PHINode *NewPN = PHINode::Create(CurrentI->getType(), Preds.size());
401       NewPN->setDebugLoc(CurrentI->getDebugLoc());
402       for (auto &Mapping : ValueToValueMaps)
403         NewPN->addIncoming(Mapping[CurrentI],
404                            cast<Instruction>(Mapping[CurrentI])->getParent());
405       NewPN->insertBefore(&*TailBB->begin());
406       CurrentI->replaceAllUsesWith(NewPN);
407     }
408     CurrentI->eraseFromParent();
409     // We are done once we handled the first original instruction in TailBB.
410     if (CurrentI == OriginalBegin)
411       break;
412   }
413 }
414 
415 // Return true if the call-site has an argument which is a PHI with only
416 // constant incoming values.
417 static bool isPredicatedOnPHI(CallBase &CB) {
418   BasicBlock *Parent = CB.getParent();
419   if (&CB != Parent->getFirstNonPHIOrDbg())
420     return false;
421 
422   for (auto &PN : Parent->phis()) {
423     for (auto &Arg : CB.args()) {
424       if (&*Arg != &PN)
425         continue;
426       assert(PN.getNumIncomingValues() == 2 &&
427              "Unexpected number of incoming values");
428       if (PN.getIncomingBlock(0) == PN.getIncomingBlock(1))
429         return false;
430       if (PN.getIncomingValue(0) == PN.getIncomingValue(1))
431         continue;
432       if (isa<Constant>(PN.getIncomingValue(0)) &&
433           isa<Constant>(PN.getIncomingValue(1)))
434         return true;
435     }
436   }
437   return false;
438 }
439 
440 using PredsWithCondsTy = SmallVector<std::pair<BasicBlock *, ConditionsTy>, 2>;
441 
442 // Check if any of the arguments in CS are predicated on a PHI node and return
443 // the set of predecessors we should use for splitting.
444 static PredsWithCondsTy shouldSplitOnPHIPredicatedArgument(CallBase &CB) {
445   if (!isPredicatedOnPHI(CB))
446     return {};
447 
448   auto Preds = getTwoPredecessors(CB.getParent());
449   return {{Preds[0], {}}, {Preds[1], {}}};
450 }
451 
452 // Checks if any of the arguments in CS are predicated in a predecessor and
453 // returns a list of predecessors with the conditions that hold on their edges
454 // to CS.
455 static PredsWithCondsTy shouldSplitOnPredicatedArgument(CallBase &CB,
456                                                         DomTreeUpdater &DTU) {
457   auto Preds = getTwoPredecessors(CB.getParent());
458   if (Preds[0] == Preds[1])
459     return {};
460 
461   // We can stop recording conditions once we reached the immediate dominator
462   // for the block containing the call site. Conditions in predecessors of the
463   // that node will be the same for all paths to the call site and splitting
464   // is not beneficial.
465   assert(DTU.hasDomTree() && "We need a DTU with a valid DT!");
466   auto *CSDTNode = DTU.getDomTree().getNode(CB.getParent());
467   BasicBlock *StopAt = CSDTNode ? CSDTNode->getIDom()->getBlock() : nullptr;
468 
469   SmallVector<std::pair<BasicBlock *, ConditionsTy>, 2> PredsCS;
470   for (auto *Pred : make_range(Preds.rbegin(), Preds.rend())) {
471     ConditionsTy Conditions;
472     // Record condition on edge BB(CS) <- Pred
473     recordCondition(CB, Pred, CB.getParent(), Conditions);
474     // Record conditions following Pred's single predecessors.
475     recordConditions(CB, Pred, Conditions, StopAt);
476     PredsCS.push_back({Pred, Conditions});
477   }
478 
479   if (all_of(PredsCS, [](const std::pair<BasicBlock *, ConditionsTy> &P) {
480         return P.second.empty();
481       }))
482     return {};
483 
484   return PredsCS;
485 }
486 
487 static bool tryToSplitCallSite(CallBase &CB, TargetTransformInfo &TTI,
488                                DomTreeUpdater &DTU) {
489   // Check if we can split the call site.
490   if (!CB.arg_size() || !canSplitCallSite(CB, TTI))
491     return false;
492 
493   auto PredsWithConds = shouldSplitOnPredicatedArgument(CB, DTU);
494   if (PredsWithConds.empty())
495     PredsWithConds = shouldSplitOnPHIPredicatedArgument(CB);
496   if (PredsWithConds.empty())
497     return false;
498 
499   splitCallSite(CB, PredsWithConds, DTU);
500   return true;
501 }
502 
503 static bool doCallSiteSplitting(Function &F, TargetLibraryInfo &TLI,
504                                 TargetTransformInfo &TTI, DominatorTree &DT) {
505 
506   DomTreeUpdater DTU(&DT, DomTreeUpdater::UpdateStrategy::Lazy);
507   bool Changed = false;
508   for (Function::iterator BI = F.begin(), BE = F.end(); BI != BE;) {
509     BasicBlock &BB = *BI++;
510     auto II = BB.getFirstNonPHIOrDbg()->getIterator();
511     auto IE = BB.getTerminator()->getIterator();
512     // Iterate until we reach the terminator instruction. tryToSplitCallSite
513     // can replace BB's terminator in case BB is a successor of itself. In that
514     // case, IE will be invalidated and we also have to check the current
515     // terminator.
516     while (II != IE && &*II != BB.getTerminator()) {
517       CallBase *CB = dyn_cast<CallBase>(&*II++);
518       if (!CB || isa<IntrinsicInst>(CB) || isInstructionTriviallyDead(CB, &TLI))
519         continue;
520 
521       Function *Callee = CB->getCalledFunction();
522       if (!Callee || Callee->isDeclaration())
523         continue;
524 
525       // Successful musttail call-site splits result in erased CI and erased BB.
526       // Check if such path is possible before attempting the splitting.
527       bool IsMustTail = CB->isMustTailCall();
528 
529       Changed |= tryToSplitCallSite(*CB, TTI, DTU);
530 
531       // There're no interesting instructions after this. The call site
532       // itself might have been erased on splitting.
533       if (IsMustTail)
534         break;
535     }
536   }
537   return Changed;
538 }
539 
540 namespace {
541 struct CallSiteSplittingLegacyPass : public FunctionPass {
542   static char ID;
543   CallSiteSplittingLegacyPass() : FunctionPass(ID) {
544     initializeCallSiteSplittingLegacyPassPass(*PassRegistry::getPassRegistry());
545   }
546 
547   void getAnalysisUsage(AnalysisUsage &AU) const override {
548     AU.addRequired<TargetLibraryInfoWrapperPass>();
549     AU.addRequired<TargetTransformInfoWrapperPass>();
550     AU.addRequired<DominatorTreeWrapperPass>();
551     AU.addPreserved<DominatorTreeWrapperPass>();
552     FunctionPass::getAnalysisUsage(AU);
553   }
554 
555   bool runOnFunction(Function &F) override {
556     if (skipFunction(F))
557       return false;
558 
559     auto &TLI = getAnalysis<TargetLibraryInfoWrapperPass>().getTLI(F);
560     auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
561     auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
562     return doCallSiteSplitting(F, TLI, TTI, DT);
563   }
564 };
565 } // namespace
566 
567 char CallSiteSplittingLegacyPass::ID = 0;
568 INITIALIZE_PASS_BEGIN(CallSiteSplittingLegacyPass, "callsite-splitting",
569                       "Call-site splitting", false, false)
570 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
571 INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
572 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
573 INITIALIZE_PASS_END(CallSiteSplittingLegacyPass, "callsite-splitting",
574                     "Call-site splitting", false, false)
575 FunctionPass *llvm::createCallSiteSplittingPass() {
576   return new CallSiteSplittingLegacyPass();
577 }
578 
579 PreservedAnalyses CallSiteSplittingPass::run(Function &F,
580                                              FunctionAnalysisManager &AM) {
581   auto &TLI = AM.getResult<TargetLibraryAnalysis>(F);
582   auto &TTI = AM.getResult<TargetIRAnalysis>(F);
583   auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
584 
585   if (!doCallSiteSplitting(F, TLI, TTI, DT))
586     return PreservedAnalyses::all();
587   PreservedAnalyses PA;
588   PA.preserve<DominatorTreeAnalysis>();
589   return PA;
590 }
591