1 //===- CloneFunction.cpp - Clone a function into another function ---------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the CloneFunctionInto interface, which is used as the
11 // low-level function cloner. This is used by the CloneFunction and function
12 // inliner to do the dirty work of copying the body of a function around.
14 //===----------------------------------------------------------------------===//
16 #include "llvm/ADT/SetVector.h"
17 #include "llvm/ADT/SmallVector.h"
18 #include "llvm/Analysis/ConstantFolding.h"
19 #include "llvm/Analysis/InstructionSimplify.h"
20 #include "llvm/Analysis/LoopInfo.h"
21 #include "llvm/IR/CFG.h"
22 #include "llvm/IR/Constants.h"
23 #include "llvm/IR/DebugInfo.h"
24 #include "llvm/IR/DerivedTypes.h"
25 #include "llvm/IR/Function.h"
26 #include "llvm/IR/GlobalVariable.h"
27 #include "llvm/IR/Instructions.h"
28 #include "llvm/IR/IntrinsicInst.h"
29 #include "llvm/IR/LLVMContext.h"
30 #include "llvm/IR/Metadata.h"
31 #include "llvm/IR/Module.h"
32 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
33 #include "llvm/Transforms/Utils/Cloning.h"
34 #include "llvm/Transforms/Utils/Local.h"
35 #include "llvm/Transforms/Utils/ValueMapper.h"
39 /// See comments in Cloning.h.
40 BasicBlock *llvm::CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap,
41 const Twine &NameSuffix, Function *F,
42 ClonedCodeInfo *CodeInfo,
43 DebugInfoFinder *DIFinder) {
44 DenseMap<const MDNode *, MDNode *> Cache;
45 BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "", F);
46 if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
48 bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
49 Module *TheModule = F ? F->getParent() : nullptr;
51 // Loop over all instructions, and copy them over.
52 for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end();
55 if (DIFinder && TheModule) {
56 if (auto *DDI = dyn_cast<DbgDeclareInst>(II))
57 DIFinder->processDeclare(*TheModule, DDI);
58 else if (auto *DVI = dyn_cast<DbgValueInst>(II))
59 DIFinder->processValue(*TheModule, DVI);
61 if (auto DbgLoc = II->getDebugLoc())
62 DIFinder->processLocation(*TheModule, DbgLoc.get());
65 Instruction *NewInst = II->clone();
67 NewInst->setName(II->getName()+NameSuffix);
68 NewBB->getInstList().push_back(NewInst);
69 VMap[&*II] = NewInst; // Add instruction map to value.
71 hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
72 if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
73 if (isa<ConstantInt>(AI->getArraySize()))
74 hasStaticAllocas = true;
76 hasDynamicAllocas = true;
81 CodeInfo->ContainsCalls |= hasCalls;
82 CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
83 CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
84 BB != &BB->getParent()->getEntryBlock();
89 // Clone OldFunc into NewFunc, transforming the old arguments into references to
92 void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
93 ValueToValueMapTy &VMap,
94 bool ModuleLevelChanges,
95 SmallVectorImpl<ReturnInst*> &Returns,
96 const char *NameSuffix, ClonedCodeInfo *CodeInfo,
97 ValueMapTypeRemapper *TypeMapper,
98 ValueMaterializer *Materializer) {
99 assert(NameSuffix && "NameSuffix cannot be null!");
102 for (const Argument &I : OldFunc->args())
103 assert(VMap.count(&I) && "No mapping from source argument specified!");
106 // Copy all attributes other than those stored in the AttributeList. We need
107 // to remap the parameter indices of the AttributeList.
108 AttributeList NewAttrs = NewFunc->getAttributes();
109 NewFunc->copyAttributesFrom(OldFunc);
110 NewFunc->setAttributes(NewAttrs);
112 // Fix up the personality function that got copied over.
113 if (OldFunc->hasPersonalityFn())
114 NewFunc->setPersonalityFn(
115 MapValue(OldFunc->getPersonalityFn(), VMap,
116 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
117 TypeMapper, Materializer));
119 SmallVector<AttributeSet, 4> NewArgAttrs(NewFunc->arg_size());
120 AttributeList OldAttrs = OldFunc->getAttributes();
122 // Clone any argument attributes that are present in the VMap.
123 for (const Argument &OldArg : OldFunc->args()) {
124 if (Argument *NewArg = dyn_cast<Argument>(VMap[&OldArg])) {
125 NewArgAttrs[NewArg->getArgNo()] =
126 OldAttrs.getParamAttributes(OldArg.getArgNo());
130 NewFunc->setAttributes(
131 AttributeList::get(NewFunc->getContext(), OldAttrs.getFnAttributes(),
132 OldAttrs.getRetAttributes(), NewArgAttrs));
135 OldFunc->getParent() && OldFunc->getParent() == NewFunc->getParent();
136 DISubprogram *SP = OldFunc->getSubprogram();
138 assert(!MustCloneSP || ModuleLevelChanges);
139 // Add mappings for some DebugInfo nodes that we don't want duplicated
140 // even if they're distinct.
141 auto &MD = VMap.MD();
142 MD[SP->getUnit()].reset(SP->getUnit());
143 MD[SP->getType()].reset(SP->getType());
144 MD[SP->getFile()].reset(SP->getFile());
145 // If we're not cloning into the same module, no need to clone the
151 SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
152 OldFunc->getAllMetadata(MDs);
153 for (auto MD : MDs) {
154 NewFunc->addMetadata(
156 *MapMetadata(MD.second, VMap,
157 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
158 TypeMapper, Materializer));
161 // When we remap instructions, we want to avoid duplicating inlined
162 // DISubprograms, so record all subprograms we find as we duplicate
163 // instructions and then freeze them in the MD map.
164 // We also record information about dbg.value and dbg.declare to avoid
165 // duplicating the types.
166 DebugInfoFinder DIFinder;
168 // Loop over all of the basic blocks in the function, cloning them as
169 // appropriate. Note that we save BE this way in order to handle cloning of
170 // recursive functions into themselves.
172 for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
174 const BasicBlock &BB = *BI;
176 // Create a new basic block and copy instructions into it!
177 BasicBlock *CBB = CloneBasicBlock(&BB, VMap, NameSuffix, NewFunc, CodeInfo,
178 SP ? &DIFinder : nullptr);
180 // Add basic block mapping.
183 // It is only legal to clone a function if a block address within that
184 // function is never referenced outside of the function. Given that, we
185 // want to map block addresses from the old function to block addresses in
186 // the clone. (This is different from the generic ValueMapper
187 // implementation, which generates an invalid blockaddress when
188 // cloning a function.)
189 if (BB.hasAddressTaken()) {
190 Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
191 const_cast<BasicBlock*>(&BB));
192 VMap[OldBBAddr] = BlockAddress::get(NewFunc, CBB);
195 // Note return instructions for the caller.
196 if (ReturnInst *RI = dyn_cast<ReturnInst>(CBB->getTerminator()))
197 Returns.push_back(RI);
200 for (DISubprogram *ISP : DIFinder.subprograms()) {
202 VMap.MD()[ISP].reset(ISP);
206 for (auto *Type : DIFinder.types()) {
207 VMap.MD()[Type].reset(Type);
210 // Loop over all of the instructions in the function, fixing up operand
211 // references as we go. This uses VMap to do all the hard work.
212 for (Function::iterator BB =
213 cast<BasicBlock>(VMap[&OldFunc->front()])->getIterator(),
216 // Loop over all instructions, fixing each one as we find it...
217 for (Instruction &II : *BB)
218 RemapInstruction(&II, VMap,
219 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
220 TypeMapper, Materializer);
223 /// Return a copy of the specified function and add it to that function's
224 /// module. Also, any references specified in the VMap are changed to refer to
225 /// their mapped value instead of the original one. If any of the arguments to
226 /// the function are in the VMap, the arguments are deleted from the resultant
227 /// function. The VMap is updated to include mappings from all of the
228 /// instructions and basicblocks in the function from their old to new values.
230 Function *llvm::CloneFunction(Function *F, ValueToValueMapTy &VMap,
231 ClonedCodeInfo *CodeInfo) {
232 std::vector<Type*> ArgTypes;
234 // The user might be deleting arguments to the function by specifying them in
235 // the VMap. If so, we need to not add the arguments to the arg ty vector
237 for (const Argument &I : F->args())
238 if (VMap.count(&I) == 0) // Haven't mapped the argument to anything yet?
239 ArgTypes.push_back(I.getType());
241 // Create a new function type...
242 FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(),
243 ArgTypes, F->getFunctionType()->isVarArg());
245 // Create the new function...
247 Function::Create(FTy, F->getLinkage(), F->getName(), F->getParent());
249 // Loop over the arguments, copying the names of the mapped arguments over...
250 Function::arg_iterator DestI = NewF->arg_begin();
251 for (const Argument & I : F->args())
252 if (VMap.count(&I) == 0) { // Is this argument preserved?
253 DestI->setName(I.getName()); // Copy the name over...
254 VMap[&I] = &*DestI++; // Add mapping to VMap
257 SmallVector<ReturnInst*, 8> Returns; // Ignore returns cloned.
258 CloneFunctionInto(NewF, F, VMap, F->getSubprogram() != nullptr, Returns, "",
267 /// This is a private class used to implement CloneAndPruneFunctionInto.
268 struct PruningFunctionCloner {
270 const Function *OldFunc;
271 ValueToValueMapTy &VMap;
272 bool ModuleLevelChanges;
273 const char *NameSuffix;
274 ClonedCodeInfo *CodeInfo;
277 PruningFunctionCloner(Function *newFunc, const Function *oldFunc,
278 ValueToValueMapTy &valueMap, bool moduleLevelChanges,
279 const char *nameSuffix, ClonedCodeInfo *codeInfo)
280 : NewFunc(newFunc), OldFunc(oldFunc), VMap(valueMap),
281 ModuleLevelChanges(moduleLevelChanges), NameSuffix(nameSuffix),
282 CodeInfo(codeInfo) {}
284 /// The specified block is found to be reachable, clone it and
285 /// anything that it can reach.
286 void CloneBlock(const BasicBlock *BB,
287 BasicBlock::const_iterator StartingInst,
288 std::vector<const BasicBlock*> &ToClone);
292 /// The specified block is found to be reachable, clone it and
293 /// anything that it can reach.
294 void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
295 BasicBlock::const_iterator StartingInst,
296 std::vector<const BasicBlock*> &ToClone){
297 WeakTrackingVH &BBEntry = VMap[BB];
299 // Have we already cloned this block?
302 // Nope, clone it now.
304 BBEntry = NewBB = BasicBlock::Create(BB->getContext());
305 if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
307 // It is only legal to clone a function if a block address within that
308 // function is never referenced outside of the function. Given that, we
309 // want to map block addresses from the old function to block addresses in
310 // the clone. (This is different from the generic ValueMapper
311 // implementation, which generates an invalid blockaddress when
312 // cloning a function.)
314 // Note that we don't need to fix the mapping for unreachable blocks;
315 // the default mapping there is safe.
316 if (BB->hasAddressTaken()) {
317 Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
318 const_cast<BasicBlock*>(BB));
319 VMap[OldBBAddr] = BlockAddress::get(NewFunc, NewBB);
322 bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
324 // Loop over all instructions, and copy them over, DCE'ing as we go. This
325 // loop doesn't include the terminator.
326 for (BasicBlock::const_iterator II = StartingInst, IE = --BB->end();
329 Instruction *NewInst = II->clone();
331 // Eagerly remap operands to the newly cloned instruction, except for PHI
332 // nodes for which we defer processing until we update the CFG.
333 if (!isa<PHINode>(NewInst)) {
334 RemapInstruction(NewInst, VMap,
335 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
337 // If we can simplify this instruction to some other value, simply add
338 // a mapping to that value rather than inserting a new instruction into
341 SimplifyInstruction(NewInst, BB->getModule()->getDataLayout())) {
342 // On the off-chance that this simplifies to an instruction in the old
343 // function, map it back into the new function.
344 if (NewFunc != OldFunc)
345 if (Value *MappedV = VMap.lookup(V))
348 if (!NewInst->mayHaveSideEffects()) {
350 NewInst->deleteValue();
357 NewInst->setName(II->getName()+NameSuffix);
358 VMap[&*II] = NewInst; // Add instruction map to value.
359 NewBB->getInstList().push_back(NewInst);
360 hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
363 if (auto CS = ImmutableCallSite(&*II))
364 if (CS.hasOperandBundles())
365 CodeInfo->OperandBundleCallSites.push_back(NewInst);
367 if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
368 if (isa<ConstantInt>(AI->getArraySize()))
369 hasStaticAllocas = true;
371 hasDynamicAllocas = true;
375 // Finally, clone over the terminator.
376 const TerminatorInst *OldTI = BB->getTerminator();
377 bool TerminatorDone = false;
378 if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) {
379 if (BI->isConditional()) {
380 // If the condition was a known constant in the callee...
381 ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
382 // Or is a known constant in the caller...
384 Value *V = VMap.lookup(BI->getCondition());
385 Cond = dyn_cast_or_null<ConstantInt>(V);
388 // Constant fold to uncond branch!
390 BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue());
391 VMap[OldTI] = BranchInst::Create(Dest, NewBB);
392 ToClone.push_back(Dest);
393 TerminatorDone = true;
396 } else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) {
397 // If switching on a value known constant in the caller.
398 ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition());
399 if (!Cond) { // Or known constant after constant prop in the callee...
400 Value *V = VMap.lookup(SI->getCondition());
401 Cond = dyn_cast_or_null<ConstantInt>(V);
403 if (Cond) { // Constant fold to uncond branch!
404 SwitchInst::ConstCaseHandle Case = *SI->findCaseValue(Cond);
405 BasicBlock *Dest = const_cast<BasicBlock*>(Case.getCaseSuccessor());
406 VMap[OldTI] = BranchInst::Create(Dest, NewBB);
407 ToClone.push_back(Dest);
408 TerminatorDone = true;
412 if (!TerminatorDone) {
413 Instruction *NewInst = OldTI->clone();
414 if (OldTI->hasName())
415 NewInst->setName(OldTI->getName()+NameSuffix);
416 NewBB->getInstList().push_back(NewInst);
417 VMap[OldTI] = NewInst; // Add instruction map to value.
420 if (auto CS = ImmutableCallSite(OldTI))
421 if (CS.hasOperandBundles())
422 CodeInfo->OperandBundleCallSites.push_back(NewInst);
424 // Recursively clone any reachable successor blocks.
425 const TerminatorInst *TI = BB->getTerminator();
426 for (const BasicBlock *Succ : TI->successors())
427 ToClone.push_back(Succ);
431 CodeInfo->ContainsCalls |= hasCalls;
432 CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
433 CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
434 BB != &BB->getParent()->front();
438 /// This works like CloneAndPruneFunctionInto, except that it does not clone the
439 /// entire function. Instead it starts at an instruction provided by the caller
440 /// and copies (and prunes) only the code reachable from that instruction.
441 void llvm::CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc,
442 const Instruction *StartingInst,
443 ValueToValueMapTy &VMap,
444 bool ModuleLevelChanges,
445 SmallVectorImpl<ReturnInst *> &Returns,
446 const char *NameSuffix,
447 ClonedCodeInfo *CodeInfo) {
448 assert(NameSuffix && "NameSuffix cannot be null!");
450 ValueMapTypeRemapper *TypeMapper = nullptr;
451 ValueMaterializer *Materializer = nullptr;
454 // If the cloning starts at the beginning of the function, verify that
455 // the function arguments are mapped.
457 for (const Argument &II : OldFunc->args())
458 assert(VMap.count(&II) && "No mapping from source argument specified!");
461 PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges,
462 NameSuffix, CodeInfo);
463 const BasicBlock *StartingBB;
465 StartingBB = StartingInst->getParent();
467 StartingBB = &OldFunc->getEntryBlock();
468 StartingInst = &StartingBB->front();
471 // Clone the entry block, and anything recursively reachable from it.
472 std::vector<const BasicBlock*> CloneWorklist;
473 PFC.CloneBlock(StartingBB, StartingInst->getIterator(), CloneWorklist);
474 while (!CloneWorklist.empty()) {
475 const BasicBlock *BB = CloneWorklist.back();
476 CloneWorklist.pop_back();
477 PFC.CloneBlock(BB, BB->begin(), CloneWorklist);
480 // Loop over all of the basic blocks in the old function. If the block was
481 // reachable, we have cloned it and the old block is now in the value map:
482 // insert it into the new function in the right order. If not, ignore it.
484 // Defer PHI resolution until rest of function is resolved.
485 SmallVector<const PHINode*, 16> PHIToResolve;
486 for (const BasicBlock &BI : *OldFunc) {
487 Value *V = VMap.lookup(&BI);
488 BasicBlock *NewBB = cast_or_null<BasicBlock>(V);
489 if (!NewBB) continue; // Dead block.
491 // Add the new block to the new function.
492 NewFunc->getBasicBlockList().push_back(NewBB);
494 // Handle PHI nodes specially, as we have to remove references to dead
496 for (const PHINode &PN : BI.phis()) {
497 // PHI nodes may have been remapped to non-PHI nodes by the caller or
498 // during the cloning process.
499 if (isa<PHINode>(VMap[&PN]))
500 PHIToResolve.push_back(&PN);
505 // Finally, remap the terminator instructions, as those can't be remapped
506 // until all BBs are mapped.
507 RemapInstruction(NewBB->getTerminator(), VMap,
508 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
509 TypeMapper, Materializer);
512 // Defer PHI resolution until rest of function is resolved, PHI resolution
513 // requires the CFG to be up-to-date.
514 for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
515 const PHINode *OPN = PHIToResolve[phino];
516 unsigned NumPreds = OPN->getNumIncomingValues();
517 const BasicBlock *OldBB = OPN->getParent();
518 BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]);
520 // Map operands for blocks that are live and remove operands for blocks
522 for (; phino != PHIToResolve.size() &&
523 PHIToResolve[phino]->getParent() == OldBB; ++phino) {
524 OPN = PHIToResolve[phino];
525 PHINode *PN = cast<PHINode>(VMap[OPN]);
526 for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
527 Value *V = VMap.lookup(PN->getIncomingBlock(pred));
528 if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) {
529 Value *InVal = MapValue(PN->getIncomingValue(pred),
531 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
532 assert(InVal && "Unknown input value?");
533 PN->setIncomingValue(pred, InVal);
534 PN->setIncomingBlock(pred, MappedBlock);
536 PN->removeIncomingValue(pred, false);
537 --pred; // Revisit the next entry.
543 // The loop above has removed PHI entries for those blocks that are dead
544 // and has updated others. However, if a block is live (i.e. copied over)
545 // but its terminator has been changed to not go to this block, then our
546 // phi nodes will have invalid entries. Update the PHI nodes in this
548 PHINode *PN = cast<PHINode>(NewBB->begin());
549 NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB));
550 if (NumPreds != PN->getNumIncomingValues()) {
551 assert(NumPreds < PN->getNumIncomingValues());
552 // Count how many times each predecessor comes to this block.
553 std::map<BasicBlock*, unsigned> PredCount;
554 for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
558 // Figure out how many entries to remove from each PHI.
559 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
560 ++PredCount[PN->getIncomingBlock(i)];
562 // At this point, the excess predecessor entries are positive in the
563 // map. Loop over all of the PHIs and remove excess predecessor
565 BasicBlock::iterator I = NewBB->begin();
566 for (; (PN = dyn_cast<PHINode>(I)); ++I) {
567 for (const auto &PCI : PredCount) {
568 BasicBlock *Pred = PCI.first;
569 for (unsigned NumToRemove = PCI.second; NumToRemove; --NumToRemove)
570 PN->removeIncomingValue(Pred, false);
575 // If the loops above have made these phi nodes have 0 or 1 operand,
576 // replace them with undef or the input value. We must do this for
577 // correctness, because 0-operand phis are not valid.
578 PN = cast<PHINode>(NewBB->begin());
579 if (PN->getNumIncomingValues() == 0) {
580 BasicBlock::iterator I = NewBB->begin();
581 BasicBlock::const_iterator OldI = OldBB->begin();
582 while ((PN = dyn_cast<PHINode>(I++))) {
583 Value *NV = UndefValue::get(PN->getType());
584 PN->replaceAllUsesWith(NV);
585 assert(VMap[&*OldI] == PN && "VMap mismatch");
587 PN->eraseFromParent();
593 // Make a second pass over the PHINodes now that all of them have been
594 // remapped into the new function, simplifying the PHINode and performing any
595 // recursive simplifications exposed. This will transparently update the
596 // WeakTrackingVH in the VMap. Notably, we rely on that so that if we coalesce
597 // two PHINodes, the iteration over the old PHIs remains valid, and the
598 // mapping will just map us to the new node (which may not even be a PHI
600 const DataLayout &DL = NewFunc->getParent()->getDataLayout();
601 SmallSetVector<const Value *, 8> Worklist;
602 for (unsigned Idx = 0, Size = PHIToResolve.size(); Idx != Size; ++Idx)
603 if (isa<PHINode>(VMap[PHIToResolve[Idx]]))
604 Worklist.insert(PHIToResolve[Idx]);
606 // Note that we must test the size on each iteration, the worklist can grow.
607 for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) {
608 const Value *OrigV = Worklist[Idx];
609 auto *I = dyn_cast_or_null<Instruction>(VMap.lookup(OrigV));
613 // Skip over non-intrinsic callsites, we don't want to remove any nodes from
615 CallSite CS = CallSite(I);
616 if (CS && CS.getCalledFunction() && !CS.getCalledFunction()->isIntrinsic())
619 // See if this instruction simplifies.
620 Value *SimpleV = SimplifyInstruction(I, DL);
624 // Stash away all the uses of the old instruction so we can check them for
625 // recursive simplifications after a RAUW. This is cheaper than checking all
626 // uses of To on the recursive step in most cases.
627 for (const User *U : OrigV->users())
628 Worklist.insert(cast<Instruction>(U));
630 // Replace the instruction with its simplified value.
631 I->replaceAllUsesWith(SimpleV);
633 // If the original instruction had no side effects, remove it.
634 if (isInstructionTriviallyDead(I))
635 I->eraseFromParent();
640 // Now that the inlined function body has been fully constructed, go through
641 // and zap unconditional fall-through branches. This happens all the time when
642 // specializing code: code specialization turns conditional branches into
643 // uncond branches, and this code folds them.
644 Function::iterator Begin = cast<BasicBlock>(VMap[StartingBB])->getIterator();
645 Function::iterator I = Begin;
646 while (I != NewFunc->end()) {
647 // Check if this block has become dead during inlining or other
648 // simplifications. Note that the first block will appear dead, as it has
649 // not yet been wired up properly.
650 if (I != Begin && (pred_begin(&*I) == pred_end(&*I) ||
651 I->getSinglePredecessor() == &*I)) {
652 BasicBlock *DeadBB = &*I++;
653 DeleteDeadBlock(DeadBB);
657 // We need to simplify conditional branches and switches with a constant
658 // operand. We try to prune these out when cloning, but if the
659 // simplification required looking through PHI nodes, those are only
660 // available after forming the full basic block. That may leave some here,
661 // and we still want to prune the dead code as early as possible.
662 ConstantFoldTerminator(&*I);
664 BranchInst *BI = dyn_cast<BranchInst>(I->getTerminator());
665 if (!BI || BI->isConditional()) { ++I; continue; }
667 BasicBlock *Dest = BI->getSuccessor(0);
668 if (!Dest->getSinglePredecessor()) {
672 // We shouldn't be able to get single-entry PHI nodes here, as instsimplify
673 // above should have zapped all of them..
674 assert(!isa<PHINode>(Dest->begin()));
676 // We know all single-entry PHI nodes in the inlined function have been
677 // removed, so we just need to splice the blocks.
678 BI->eraseFromParent();
680 // Make all PHI nodes that referred to Dest now refer to I as their source.
681 Dest->replaceAllUsesWith(&*I);
683 // Move all the instructions in the succ to the pred.
684 I->getInstList().splice(I->end(), Dest->getInstList());
686 // Remove the dest block.
687 Dest->eraseFromParent();
689 // Do not increment I, iteratively merge all things this block branches to.
692 // Make a final pass over the basic blocks from the old function to gather
693 // any return instructions which survived folding. We have to do this here
694 // because we can iteratively remove and merge returns above.
695 for (Function::iterator I = cast<BasicBlock>(VMap[StartingBB])->getIterator(),
698 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator()))
699 Returns.push_back(RI);
703 /// This works exactly like CloneFunctionInto,
704 /// except that it does some simple constant prop and DCE on the fly. The
705 /// effect of this is to copy significantly less code in cases where (for
706 /// example) a function call with constant arguments is inlined, and those
707 /// constant arguments cause a significant amount of code in the callee to be
708 /// dead. Since this doesn't produce an exact copy of the input, it can't be
709 /// used for things like CloneFunction or CloneModule.
710 void llvm::CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
711 ValueToValueMapTy &VMap,
712 bool ModuleLevelChanges,
713 SmallVectorImpl<ReturnInst*> &Returns,
714 const char *NameSuffix,
715 ClonedCodeInfo *CodeInfo,
716 Instruction *TheCall) {
717 CloneAndPruneIntoFromInst(NewFunc, OldFunc, &OldFunc->front().front(), VMap,
718 ModuleLevelChanges, Returns, NameSuffix, CodeInfo);
721 /// \brief Remaps instructions in \p Blocks using the mapping in \p VMap.
722 void llvm::remapInstructionsInBlocks(
723 const SmallVectorImpl<BasicBlock *> &Blocks, ValueToValueMapTy &VMap) {
724 // Rewrite the code to refer to itself.
725 for (auto *BB : Blocks)
726 for (auto &Inst : *BB)
727 RemapInstruction(&Inst, VMap,
728 RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
731 /// \brief Clones a loop \p OrigLoop. Returns the loop and the blocks in \p
734 /// Updates LoopInfo and DominatorTree assuming the loop is dominated by block
735 /// \p LoopDomBB. Insert the new blocks before block specified in \p Before.
736 Loop *llvm::cloneLoopWithPreheader(BasicBlock *Before, BasicBlock *LoopDomBB,
737 Loop *OrigLoop, ValueToValueMapTy &VMap,
738 const Twine &NameSuffix, LoopInfo *LI,
740 SmallVectorImpl<BasicBlock *> &Blocks) {
741 assert(OrigLoop->getSubLoops().empty() &&
742 "Loop to be cloned cannot have inner loop");
743 Function *F = OrigLoop->getHeader()->getParent();
744 Loop *ParentLoop = OrigLoop->getParentLoop();
746 Loop *NewLoop = LI->AllocateLoop();
748 ParentLoop->addChildLoop(NewLoop);
750 LI->addTopLevelLoop(NewLoop);
752 BasicBlock *OrigPH = OrigLoop->getLoopPreheader();
753 assert(OrigPH && "No preheader");
754 BasicBlock *NewPH = CloneBasicBlock(OrigPH, VMap, NameSuffix, F);
755 // To rename the loop PHIs.
756 VMap[OrigPH] = NewPH;
757 Blocks.push_back(NewPH);
761 ParentLoop->addBasicBlockToLoop(NewPH, *LI);
763 // Update DominatorTree.
764 DT->addNewBlock(NewPH, LoopDomBB);
766 for (BasicBlock *BB : OrigLoop->getBlocks()) {
767 BasicBlock *NewBB = CloneBasicBlock(BB, VMap, NameSuffix, F);
771 NewLoop->addBasicBlockToLoop(NewBB, *LI);
773 // Add DominatorTree node. After seeing all blocks, update to correct IDom.
774 DT->addNewBlock(NewBB, NewPH);
776 Blocks.push_back(NewBB);
779 for (BasicBlock *BB : OrigLoop->getBlocks()) {
780 // Update DominatorTree.
781 BasicBlock *IDomBB = DT->getNode(BB)->getIDom()->getBlock();
782 DT->changeImmediateDominator(cast<BasicBlock>(VMap[BB]),
783 cast<BasicBlock>(VMap[IDomBB]));
786 // Move them physically from the end of the block list.
787 F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(),
789 F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(),
790 NewLoop->getHeader()->getIterator(), F->end());
795 /// \brief Duplicate non-Phi instructions from the beginning of block up to
796 /// StopAt instruction into a split block between BB and its predecessor.
798 llvm::DuplicateInstructionsInSplitBetween(BasicBlock *BB, BasicBlock *PredBB,
800 ValueToValueMapTy &ValueMapping) {
801 // We are going to have to map operands from the original BB block to the new
802 // copy of the block 'NewBB'. If there are PHI nodes in BB, evaluate them to
803 // account for entry from PredBB.
804 BasicBlock::iterator BI = BB->begin();
805 for (; PHINode *PN = dyn_cast<PHINode>(BI); ++BI)
806 ValueMapping[PN] = PN->getIncomingValueForBlock(PredBB);
808 BasicBlock *NewBB = SplitEdge(PredBB, BB);
809 NewBB->setName(PredBB->getName() + ".split");
810 Instruction *NewTerm = NewBB->getTerminator();
812 // Clone the non-phi instructions of BB into NewBB, keeping track of the
813 // mapping and using it to remap operands in the cloned instructions.
814 for (; StopAt != &*BI; ++BI) {
815 Instruction *New = BI->clone();
816 New->setName(BI->getName());
817 New->insertBefore(NewTerm);
818 ValueMapping[&*BI] = New;
820 // Remap operands to patch up intra-block references.
821 for (unsigned i = 0, e = New->getNumOperands(); i != e; ++i)
822 if (Instruction *Inst = dyn_cast<Instruction>(New->getOperand(i))) {
823 auto I = ValueMapping.find(Inst);
824 if (I != ValueMapping.end())
825 New->setOperand(i, I->second);