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/Transforms/Utils/Cloning.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/Local.h"
34 #include "llvm/Transforms/Utils/ValueMapper.h"
38 /// See comments in Cloning.h.
39 BasicBlock *llvm::CloneBasicBlock(const BasicBlock *BB,
40 ValueToValueMapTy &VMap,
41 const Twine &NameSuffix, Function *F,
42 ClonedCodeInfo *CodeInfo) {
43 BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "", F);
44 if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
46 bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
48 // Loop over all instructions, and copy them over.
49 for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end();
51 Instruction *NewInst = II->clone();
53 NewInst->setName(II->getName()+NameSuffix);
54 NewBB->getInstList().push_back(NewInst);
55 VMap[&*II] = NewInst; // Add instruction map to value.
57 hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
58 if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
59 if (isa<ConstantInt>(AI->getArraySize()))
60 hasStaticAllocas = true;
62 hasDynamicAllocas = true;
67 CodeInfo->ContainsCalls |= hasCalls;
68 CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
69 CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
70 BB != &BB->getParent()->getEntryBlock();
75 // Clone OldFunc into NewFunc, transforming the old arguments into references to
78 void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
79 ValueToValueMapTy &VMap,
80 bool ModuleLevelChanges,
81 SmallVectorImpl<ReturnInst*> &Returns,
82 const char *NameSuffix, ClonedCodeInfo *CodeInfo,
83 ValueMapTypeRemapper *TypeMapper,
84 ValueMaterializer *Materializer) {
85 assert(NameSuffix && "NameSuffix cannot be null!");
88 for (const Argument &I : OldFunc->args())
89 assert(VMap.count(&I) && "No mapping from source argument specified!");
92 // Copy all attributes other than those stored in the AttributeSet. We need
93 // to remap the parameter indices of the AttributeSet.
94 AttributeSet NewAttrs = NewFunc->getAttributes();
95 NewFunc->copyAttributesFrom(OldFunc);
96 NewFunc->setAttributes(NewAttrs);
98 // Fix up the personality function that got copied over.
99 if (OldFunc->hasPersonalityFn())
100 NewFunc->setPersonalityFn(
101 MapValue(OldFunc->getPersonalityFn(), VMap,
102 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
103 TypeMapper, Materializer));
105 AttributeSet OldAttrs = OldFunc->getAttributes();
106 // Clone any argument attributes that are present in the VMap.
107 for (const Argument &OldArg : OldFunc->args())
108 if (Argument *NewArg = dyn_cast<Argument>(VMap[&OldArg])) {
110 OldAttrs.getParamAttributes(OldArg.getArgNo() + 1);
111 if (attrs.getNumSlots() > 0)
112 NewArg->addAttr(attrs);
115 NewFunc->setAttributes(
116 NewFunc->getAttributes()
117 .addAttributes(NewFunc->getContext(), AttributeSet::ReturnIndex,
118 OldAttrs.getRetAttributes())
119 .addAttributes(NewFunc->getContext(), AttributeSet::FunctionIndex,
120 OldAttrs.getFnAttributes()));
122 // Loop over all of the basic blocks in the function, cloning them as
123 // appropriate. Note that we save BE this way in order to handle cloning of
124 // recursive functions into themselves.
126 for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
128 const BasicBlock &BB = *BI;
130 // Create a new basic block and copy instructions into it!
131 BasicBlock *CBB = CloneBasicBlock(&BB, VMap, NameSuffix, NewFunc, CodeInfo);
133 // Add basic block mapping.
136 // It is only legal to clone a function if a block address within that
137 // function is never referenced outside of the function. Given that, we
138 // want to map block addresses from the old function to block addresses in
139 // the clone. (This is different from the generic ValueMapper
140 // implementation, which generates an invalid blockaddress when
141 // cloning a function.)
142 if (BB.hasAddressTaken()) {
143 Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
144 const_cast<BasicBlock*>(&BB));
145 VMap[OldBBAddr] = BlockAddress::get(NewFunc, CBB);
148 // Note return instructions for the caller.
149 if (ReturnInst *RI = dyn_cast<ReturnInst>(CBB->getTerminator()))
150 Returns.push_back(RI);
153 // Loop over all of the instructions in the function, fixing up operand
154 // references as we go. This uses VMap to do all the hard work.
155 for (Function::iterator BB =
156 cast<BasicBlock>(VMap[&OldFunc->front()])->getIterator(),
159 // Loop over all instructions, fixing each one as we find it...
160 for (Instruction &II : *BB)
161 RemapInstruction(&II, VMap,
162 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
163 TypeMapper, Materializer);
166 // Find the MDNode which corresponds to the subprogram data that described F.
167 static DISubprogram *FindSubprogram(const Function *F,
168 DebugInfoFinder &Finder) {
169 for (DISubprogram *Subprogram : Finder.subprograms()) {
170 if (Subprogram->describes(F))
176 // Add an operand to an existing MDNode. The new operand will be added at the
177 // back of the operand list.
178 static void AddOperand(DICompileUnit *CU, DISubprogramArray SPs,
180 SmallVector<Metadata *, 16> NewSPs;
181 NewSPs.reserve(SPs.size() + 1);
183 NewSPs.push_back(SP);
184 NewSPs.push_back(NewSP);
185 CU->replaceSubprograms(MDTuple::get(CU->getContext(), NewSPs));
188 // Clone the module-level debug info associated with OldFunc. The cloned data
189 // will point to NewFunc instead.
190 static void CloneDebugInfoMetadata(Function *NewFunc, const Function *OldFunc,
191 ValueToValueMapTy &VMap) {
192 DebugInfoFinder Finder;
193 Finder.processModule(*OldFunc->getParent());
195 const DISubprogram *OldSubprogramMDNode = FindSubprogram(OldFunc, Finder);
196 if (!OldSubprogramMDNode) return;
198 auto *NewSubprogram =
199 cast<DISubprogram>(MapMetadata(OldSubprogramMDNode, VMap));
200 NewFunc->setSubprogram(NewSubprogram);
202 for (auto *CU : Finder.compile_units()) {
203 auto Subprograms = CU->getSubprograms();
204 // If the compile unit's function list contains the old function, it should
205 // also contain the new one.
206 for (auto *SP : Subprograms) {
207 if (SP == OldSubprogramMDNode) {
208 AddOperand(CU, Subprograms, NewSubprogram);
215 /// Return a copy of the specified function, but without
216 /// embedding the function into another module. Also, any references specified
217 /// in the VMap are changed to refer to their mapped value instead of the
218 /// original one. If any of the arguments to the function are in the VMap,
219 /// the arguments are deleted from the resultant function. The VMap is
220 /// updated to include mappings from all of the instructions and basicblocks in
221 /// the function from their old to new values.
223 Function *llvm::CloneFunction(const Function *F, ValueToValueMapTy &VMap,
224 bool ModuleLevelChanges,
225 ClonedCodeInfo *CodeInfo) {
226 std::vector<Type*> ArgTypes;
228 // The user might be deleting arguments to the function by specifying them in
229 // the VMap. If so, we need to not add the arguments to the arg ty vector
231 for (const Argument &I : F->args())
232 if (VMap.count(&I) == 0) // Haven't mapped the argument to anything yet?
233 ArgTypes.push_back(I.getType());
235 // Create a new function type...
236 FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(),
237 ArgTypes, F->getFunctionType()->isVarArg());
239 // Create the new function...
240 Function *NewF = Function::Create(FTy, F->getLinkage(), F->getName());
242 // Loop over the arguments, copying the names of the mapped arguments over...
243 Function::arg_iterator DestI = NewF->arg_begin();
244 for (const Argument & I : F->args())
245 if (VMap.count(&I) == 0) { // Is this argument preserved?
246 DestI->setName(I.getName()); // Copy the name over...
247 VMap[&I] = &*DestI++; // Add mapping to VMap
250 if (ModuleLevelChanges)
251 CloneDebugInfoMetadata(NewF, F, VMap);
253 SmallVector<ReturnInst*, 8> Returns; // Ignore returns cloned.
254 CloneFunctionInto(NewF, F, VMap, ModuleLevelChanges, Returns, "", CodeInfo);
261 /// This is a private class used to implement CloneAndPruneFunctionInto.
262 struct PruningFunctionCloner {
264 const Function *OldFunc;
265 ValueToValueMapTy &VMap;
266 bool ModuleLevelChanges;
267 const char *NameSuffix;
268 ClonedCodeInfo *CodeInfo;
269 CloningDirector *Director;
270 ValueMapTypeRemapper *TypeMapper;
271 ValueMaterializer *Materializer;
274 PruningFunctionCloner(Function *newFunc, const Function *oldFunc,
275 ValueToValueMapTy &valueMap, bool moduleLevelChanges,
276 const char *nameSuffix, ClonedCodeInfo *codeInfo,
277 CloningDirector *Director)
278 : NewFunc(newFunc), OldFunc(oldFunc), VMap(valueMap),
279 ModuleLevelChanges(moduleLevelChanges), NameSuffix(nameSuffix),
280 CodeInfo(codeInfo), Director(Director) {
281 // These are optional components. The Director may return null.
283 TypeMapper = Director->getTypeRemapper();
284 Materializer = Director->getValueMaterializer();
286 TypeMapper = nullptr;
287 Materializer = nullptr;
291 /// The specified block is found to be reachable, clone it and
292 /// anything that it can reach.
293 void CloneBlock(const BasicBlock *BB,
294 BasicBlock::const_iterator StartingInst,
295 std::vector<const BasicBlock*> &ToClone);
299 /// The specified block is found to be reachable, clone it and
300 /// anything that it can reach.
301 void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
302 BasicBlock::const_iterator StartingInst,
303 std::vector<const BasicBlock*> &ToClone){
304 WeakVH &BBEntry = VMap[BB];
306 // Have we already cloned this block?
309 // Nope, clone it now.
311 BBEntry = NewBB = BasicBlock::Create(BB->getContext());
312 if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
314 // It is only legal to clone a function if a block address within that
315 // function is never referenced outside of the function. Given that, we
316 // want to map block addresses from the old function to block addresses in
317 // the clone. (This is different from the generic ValueMapper
318 // implementation, which generates an invalid blockaddress when
319 // cloning a function.)
321 // Note that we don't need to fix the mapping for unreachable blocks;
322 // the default mapping there is safe.
323 if (BB->hasAddressTaken()) {
324 Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
325 const_cast<BasicBlock*>(BB));
326 VMap[OldBBAddr] = BlockAddress::get(NewFunc, NewBB);
329 bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
331 // Loop over all instructions, and copy them over, DCE'ing as we go. This
332 // loop doesn't include the terminator.
333 for (BasicBlock::const_iterator II = StartingInst, IE = --BB->end();
335 // If the "Director" remaps the instruction, don't clone it.
337 CloningDirector::CloningAction Action =
338 Director->handleInstruction(VMap, &*II, NewBB);
339 // If the cloning director says stop, we want to stop everything, not
340 // just break out of the loop (which would cause the terminator to be
341 // cloned). The cloning director is responsible for inserting a proper
342 // terminator into the new basic block in this case.
343 if (Action == CloningDirector::StopCloningBB)
345 // If the cloning director says skip, continue to the next instruction.
346 // In this case, the cloning director is responsible for mapping the
347 // skipped instruction to some value that is defined in the new
349 if (Action == CloningDirector::SkipInstruction)
353 Instruction *NewInst = II->clone();
355 // Eagerly remap operands to the newly cloned instruction, except for PHI
356 // nodes for which we defer processing until we update the CFG.
357 if (!isa<PHINode>(NewInst)) {
358 RemapInstruction(NewInst, VMap,
359 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
360 TypeMapper, Materializer);
362 // If we can simplify this instruction to some other value, simply add
363 // a mapping to that value rather than inserting a new instruction into
366 SimplifyInstruction(NewInst, BB->getModule()->getDataLayout())) {
367 // On the off-chance that this simplifies to an instruction in the old
368 // function, map it back into the new function.
369 if (Value *MappedV = VMap.lookup(V))
379 NewInst->setName(II->getName()+NameSuffix);
380 VMap[&*II] = NewInst; // Add instruction map to value.
381 NewBB->getInstList().push_back(NewInst);
382 hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
383 if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
384 if (isa<ConstantInt>(AI->getArraySize()))
385 hasStaticAllocas = true;
387 hasDynamicAllocas = true;
391 // Finally, clone over the terminator.
392 const TerminatorInst *OldTI = BB->getTerminator();
393 bool TerminatorDone = false;
395 CloningDirector::CloningAction Action
396 = Director->handleInstruction(VMap, OldTI, NewBB);
397 // If the cloning director says stop, we want to stop everything, not
398 // just break out of the loop (which would cause the terminator to be
399 // cloned). The cloning director is responsible for inserting a proper
400 // terminator into the new basic block in this case.
401 if (Action == CloningDirector::StopCloningBB)
403 if (Action == CloningDirector::CloneSuccessors) {
404 // If the director says to skip with a terminate instruction, we still
405 // need to clone this block's successors.
406 const TerminatorInst *TI = NewBB->getTerminator();
407 for (const BasicBlock *Succ : TI->successors())
408 ToClone.push_back(Succ);
411 assert(Action != CloningDirector::SkipInstruction &&
412 "SkipInstruction is not valid for terminators.");
414 if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) {
415 if (BI->isConditional()) {
416 // If the condition was a known constant in the callee...
417 ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
418 // Or is a known constant in the caller...
420 Value *V = VMap[BI->getCondition()];
421 Cond = dyn_cast_or_null<ConstantInt>(V);
424 // Constant fold to uncond branch!
426 BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue());
427 VMap[OldTI] = BranchInst::Create(Dest, NewBB);
428 ToClone.push_back(Dest);
429 TerminatorDone = true;
432 } else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) {
433 // If switching on a value known constant in the caller.
434 ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition());
435 if (!Cond) { // Or known constant after constant prop in the callee...
436 Value *V = VMap[SI->getCondition()];
437 Cond = dyn_cast_or_null<ConstantInt>(V);
439 if (Cond) { // Constant fold to uncond branch!
440 SwitchInst::ConstCaseIt Case = SI->findCaseValue(Cond);
441 BasicBlock *Dest = const_cast<BasicBlock*>(Case.getCaseSuccessor());
442 VMap[OldTI] = BranchInst::Create(Dest, NewBB);
443 ToClone.push_back(Dest);
444 TerminatorDone = true;
448 if (!TerminatorDone) {
449 Instruction *NewInst = OldTI->clone();
450 if (OldTI->hasName())
451 NewInst->setName(OldTI->getName()+NameSuffix);
452 NewBB->getInstList().push_back(NewInst);
453 VMap[OldTI] = NewInst; // Add instruction map to value.
455 // Recursively clone any reachable successor blocks.
456 const TerminatorInst *TI = BB->getTerminator();
457 for (const BasicBlock *Succ : TI->successors())
458 ToClone.push_back(Succ);
462 CodeInfo->ContainsCalls |= hasCalls;
463 CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
464 CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
465 BB != &BB->getParent()->front();
469 /// This works like CloneAndPruneFunctionInto, except that it does not clone the
470 /// entire function. Instead it starts at an instruction provided by the caller
471 /// and copies (and prunes) only the code reachable from that instruction.
472 void llvm::CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc,
473 const Instruction *StartingInst,
474 ValueToValueMapTy &VMap,
475 bool ModuleLevelChanges,
476 SmallVectorImpl<ReturnInst *> &Returns,
477 const char *NameSuffix,
478 ClonedCodeInfo *CodeInfo,
479 CloningDirector *Director) {
480 assert(NameSuffix && "NameSuffix cannot be null!");
482 ValueMapTypeRemapper *TypeMapper = nullptr;
483 ValueMaterializer *Materializer = nullptr;
486 TypeMapper = Director->getTypeRemapper();
487 Materializer = Director->getValueMaterializer();
491 // If the cloning starts at the beginning of the function, verify that
492 // the function arguments are mapped.
494 for (const Argument &II : OldFunc->args())
495 assert(VMap.count(&II) && "No mapping from source argument specified!");
498 PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges,
499 NameSuffix, CodeInfo, Director);
500 const BasicBlock *StartingBB;
502 StartingBB = StartingInst->getParent();
504 StartingBB = &OldFunc->getEntryBlock();
505 StartingInst = &StartingBB->front();
508 // Clone the entry block, and anything recursively reachable from it.
509 std::vector<const BasicBlock*> CloneWorklist;
510 PFC.CloneBlock(StartingBB, StartingInst->getIterator(), CloneWorklist);
511 while (!CloneWorklist.empty()) {
512 const BasicBlock *BB = CloneWorklist.back();
513 CloneWorklist.pop_back();
514 PFC.CloneBlock(BB, BB->begin(), CloneWorklist);
517 // Loop over all of the basic blocks in the old function. If the block was
518 // reachable, we have cloned it and the old block is now in the value map:
519 // insert it into the new function in the right order. If not, ignore it.
521 // Defer PHI resolution until rest of function is resolved.
522 SmallVector<const PHINode*, 16> PHIToResolve;
523 for (const BasicBlock &BI : *OldFunc) {
524 Value *V = VMap[&BI];
525 BasicBlock *NewBB = cast_or_null<BasicBlock>(V);
526 if (!NewBB) continue; // Dead block.
528 // Add the new block to the new function.
529 NewFunc->getBasicBlockList().push_back(NewBB);
531 // Handle PHI nodes specially, as we have to remove references to dead
533 for (BasicBlock::const_iterator I = BI.begin(), E = BI.end(); I != E; ++I) {
534 // PHI nodes may have been remapped to non-PHI nodes by the caller or
535 // during the cloning process.
536 if (const PHINode *PN = dyn_cast<PHINode>(I)) {
537 if (isa<PHINode>(VMap[PN]))
538 PHIToResolve.push_back(PN);
546 // Finally, remap the terminator instructions, as those can't be remapped
547 // until all BBs are mapped.
548 RemapInstruction(NewBB->getTerminator(), VMap,
549 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
550 TypeMapper, Materializer);
553 // Defer PHI resolution until rest of function is resolved, PHI resolution
554 // requires the CFG to be up-to-date.
555 for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
556 const PHINode *OPN = PHIToResolve[phino];
557 unsigned NumPreds = OPN->getNumIncomingValues();
558 const BasicBlock *OldBB = OPN->getParent();
559 BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]);
561 // Map operands for blocks that are live and remove operands for blocks
563 for (; phino != PHIToResolve.size() &&
564 PHIToResolve[phino]->getParent() == OldBB; ++phino) {
565 OPN = PHIToResolve[phino];
566 PHINode *PN = cast<PHINode>(VMap[OPN]);
567 for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
568 Value *V = VMap[PN->getIncomingBlock(pred)];
569 if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) {
570 Value *InVal = MapValue(PN->getIncomingValue(pred),
572 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
573 assert(InVal && "Unknown input value?");
574 PN->setIncomingValue(pred, InVal);
575 PN->setIncomingBlock(pred, MappedBlock);
577 PN->removeIncomingValue(pred, false);
578 --pred, --e; // Revisit the next entry.
583 // The loop above has removed PHI entries for those blocks that are dead
584 // and has updated others. However, if a block is live (i.e. copied over)
585 // but its terminator has been changed to not go to this block, then our
586 // phi nodes will have invalid entries. Update the PHI nodes in this
588 PHINode *PN = cast<PHINode>(NewBB->begin());
589 NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB));
590 if (NumPreds != PN->getNumIncomingValues()) {
591 assert(NumPreds < PN->getNumIncomingValues());
592 // Count how many times each predecessor comes to this block.
593 std::map<BasicBlock*, unsigned> PredCount;
594 for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
598 // Figure out how many entries to remove from each PHI.
599 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
600 ++PredCount[PN->getIncomingBlock(i)];
602 // At this point, the excess predecessor entries are positive in the
603 // map. Loop over all of the PHIs and remove excess predecessor
605 BasicBlock::iterator I = NewBB->begin();
606 for (; (PN = dyn_cast<PHINode>(I)); ++I) {
607 for (std::map<BasicBlock*, unsigned>::iterator PCI =PredCount.begin(),
608 E = PredCount.end(); PCI != E; ++PCI) {
609 BasicBlock *Pred = PCI->first;
610 for (unsigned NumToRemove = PCI->second; NumToRemove; --NumToRemove)
611 PN->removeIncomingValue(Pred, false);
616 // If the loops above have made these phi nodes have 0 or 1 operand,
617 // replace them with undef or the input value. We must do this for
618 // correctness, because 0-operand phis are not valid.
619 PN = cast<PHINode>(NewBB->begin());
620 if (PN->getNumIncomingValues() == 0) {
621 BasicBlock::iterator I = NewBB->begin();
622 BasicBlock::const_iterator OldI = OldBB->begin();
623 while ((PN = dyn_cast<PHINode>(I++))) {
624 Value *NV = UndefValue::get(PN->getType());
625 PN->replaceAllUsesWith(NV);
626 assert(VMap[&*OldI] == PN && "VMap mismatch");
628 PN->eraseFromParent();
634 // Make a second pass over the PHINodes now that all of them have been
635 // remapped into the new function, simplifying the PHINode and performing any
636 // recursive simplifications exposed. This will transparently update the
637 // WeakVH in the VMap. Notably, we rely on that so that if we coalesce
638 // two PHINodes, the iteration over the old PHIs remains valid, and the
639 // mapping will just map us to the new node (which may not even be a PHI
641 for (unsigned Idx = 0, Size = PHIToResolve.size(); Idx != Size; ++Idx)
642 if (PHINode *PN = dyn_cast<PHINode>(VMap[PHIToResolve[Idx]]))
643 recursivelySimplifyInstruction(PN);
645 // Now that the inlined function body has been fully constructed, go through
646 // and zap unconditional fall-through branches. This happens all the time when
647 // specializing code: code specialization turns conditional branches into
648 // uncond branches, and this code folds them.
649 Function::iterator Begin = cast<BasicBlock>(VMap[StartingBB])->getIterator();
650 Function::iterator I = Begin;
651 while (I != NewFunc->end()) {
652 // Check if this block has become dead during inlining or other
653 // simplifications. Note that the first block will appear dead, as it has
654 // not yet been wired up properly.
655 if (I != Begin && (pred_begin(&*I) == pred_end(&*I) ||
656 I->getSinglePredecessor() == &*I)) {
657 BasicBlock *DeadBB = &*I++;
658 DeleteDeadBlock(DeadBB);
662 // We need to simplify conditional branches and switches with a constant
663 // operand. We try to prune these out when cloning, but if the
664 // simplification required looking through PHI nodes, those are only
665 // available after forming the full basic block. That may leave some here,
666 // and we still want to prune the dead code as early as possible.
667 ConstantFoldTerminator(&*I);
669 BranchInst *BI = dyn_cast<BranchInst>(I->getTerminator());
670 if (!BI || BI->isConditional()) { ++I; continue; }
672 BasicBlock *Dest = BI->getSuccessor(0);
673 if (!Dest->getSinglePredecessor()) {
677 // We shouldn't be able to get single-entry PHI nodes here, as instsimplify
678 // above should have zapped all of them..
679 assert(!isa<PHINode>(Dest->begin()));
681 // We know all single-entry PHI nodes in the inlined function have been
682 // removed, so we just need to splice the blocks.
683 BI->eraseFromParent();
685 // Make all PHI nodes that referred to Dest now refer to I as their source.
686 Dest->replaceAllUsesWith(&*I);
688 // Move all the instructions in the succ to the pred.
689 I->getInstList().splice(I->end(), Dest->getInstList());
691 // Remove the dest block.
692 Dest->eraseFromParent();
694 // Do not increment I, iteratively merge all things this block branches to.
697 // Make a final pass over the basic blocks from the old function to gather
698 // any return instructions which survived folding. We have to do this here
699 // because we can iteratively remove and merge returns above.
700 for (Function::iterator I = cast<BasicBlock>(VMap[StartingBB])->getIterator(),
703 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator()))
704 Returns.push_back(RI);
708 /// This works exactly like CloneFunctionInto,
709 /// except that it does some simple constant prop and DCE on the fly. The
710 /// effect of this is to copy significantly less code in cases where (for
711 /// example) a function call with constant arguments is inlined, and those
712 /// constant arguments cause a significant amount of code in the callee to be
713 /// dead. Since this doesn't produce an exact copy of the input, it can't be
714 /// used for things like CloneFunction or CloneModule.
715 void llvm::CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
716 ValueToValueMapTy &VMap,
717 bool ModuleLevelChanges,
718 SmallVectorImpl<ReturnInst*> &Returns,
719 const char *NameSuffix,
720 ClonedCodeInfo *CodeInfo,
721 Instruction *TheCall) {
722 CloneAndPruneIntoFromInst(NewFunc, OldFunc, &OldFunc->front().front(), VMap,
723 ModuleLevelChanges, Returns, NameSuffix, CodeInfo,
727 /// \brief Remaps instructions in \p Blocks using the mapping in \p VMap.
728 void llvm::remapInstructionsInBlocks(
729 const SmallVectorImpl<BasicBlock *> &Blocks, ValueToValueMapTy &VMap) {
730 // Rewrite the code to refer to itself.
731 for (auto *BB : Blocks)
732 for (auto &Inst : *BB)
733 RemapInstruction(&Inst, VMap,
734 RF_NoModuleLevelChanges | RF_IgnoreMissingEntries);
737 /// \brief Clones a loop \p OrigLoop. Returns the loop and the blocks in \p
740 /// Updates LoopInfo and DominatorTree assuming the loop is dominated by block
741 /// \p LoopDomBB. Insert the new blocks before block specified in \p Before.
742 Loop *llvm::cloneLoopWithPreheader(BasicBlock *Before, BasicBlock *LoopDomBB,
743 Loop *OrigLoop, ValueToValueMapTy &VMap,
744 const Twine &NameSuffix, LoopInfo *LI,
746 SmallVectorImpl<BasicBlock *> &Blocks) {
747 Function *F = OrigLoop->getHeader()->getParent();
748 Loop *ParentLoop = OrigLoop->getParentLoop();
750 Loop *NewLoop = new Loop();
752 ParentLoop->addChildLoop(NewLoop);
754 LI->addTopLevelLoop(NewLoop);
756 BasicBlock *OrigPH = OrigLoop->getLoopPreheader();
757 assert(OrigPH && "No preheader");
758 BasicBlock *NewPH = CloneBasicBlock(OrigPH, VMap, NameSuffix, F);
759 // To rename the loop PHIs.
760 VMap[OrigPH] = NewPH;
761 Blocks.push_back(NewPH);
765 ParentLoop->addBasicBlockToLoop(NewPH, *LI);
767 // Update DominatorTree.
768 DT->addNewBlock(NewPH, LoopDomBB);
770 for (BasicBlock *BB : OrigLoop->getBlocks()) {
771 BasicBlock *NewBB = CloneBasicBlock(BB, VMap, NameSuffix, F);
775 NewLoop->addBasicBlockToLoop(NewBB, *LI);
777 // Update DominatorTree.
778 BasicBlock *IDomBB = DT->getNode(BB)->getIDom()->getBlock();
779 DT->addNewBlock(NewBB, cast<BasicBlock>(VMap[IDomBB]));
781 Blocks.push_back(NewBB);
784 // Move them physically from the end of the block list.
785 F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(),
787 F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(),
788 NewLoop->getHeader()->getIterator(), F->end());