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 AttributeSet OldAttrs = OldFunc->getAttributes();
99 // Clone any argument attributes that are present in the VMap.
100 for (const Argument &OldArg : OldFunc->args())
101 if (Argument *NewArg = dyn_cast<Argument>(VMap[&OldArg])) {
103 OldAttrs.getParamAttributes(OldArg.getArgNo() + 1);
104 if (attrs.getNumSlots() > 0)
105 NewArg->addAttr(attrs);
108 NewFunc->setAttributes(
109 NewFunc->getAttributes()
110 .addAttributes(NewFunc->getContext(), AttributeSet::ReturnIndex,
111 OldAttrs.getRetAttributes())
112 .addAttributes(NewFunc->getContext(), AttributeSet::FunctionIndex,
113 OldAttrs.getFnAttributes()));
115 // Loop over all of the basic blocks in the function, cloning them as
116 // appropriate. Note that we save BE this way in order to handle cloning of
117 // recursive functions into themselves.
119 for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
121 const BasicBlock &BB = *BI;
123 // Create a new basic block and copy instructions into it!
124 BasicBlock *CBB = CloneBasicBlock(&BB, VMap, NameSuffix, NewFunc, CodeInfo);
126 // Add basic block mapping.
129 // It is only legal to clone a function if a block address within that
130 // function is never referenced outside of the function. Given that, we
131 // want to map block addresses from the old function to block addresses in
132 // the clone. (This is different from the generic ValueMapper
133 // implementation, which generates an invalid blockaddress when
134 // cloning a function.)
135 if (BB.hasAddressTaken()) {
136 Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
137 const_cast<BasicBlock*>(&BB));
138 VMap[OldBBAddr] = BlockAddress::get(NewFunc, CBB);
141 // Note return instructions for the caller.
142 if (ReturnInst *RI = dyn_cast<ReturnInst>(CBB->getTerminator()))
143 Returns.push_back(RI);
146 // Loop over all of the instructions in the function, fixing up operand
147 // references as we go. This uses VMap to do all the hard work.
148 for (Function::iterator BB =
149 cast<BasicBlock>(VMap[&OldFunc->front()])->getIterator(),
152 // Loop over all instructions, fixing each one as we find it...
153 for (Instruction &II : *BB)
154 RemapInstruction(&II, VMap,
155 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
156 TypeMapper, Materializer);
159 // Find the MDNode which corresponds to the subprogram data that described F.
160 static DISubprogram *FindSubprogram(const Function *F,
161 DebugInfoFinder &Finder) {
162 for (DISubprogram *Subprogram : Finder.subprograms()) {
163 if (Subprogram->describes(F))
169 // Add an operand to an existing MDNode. The new operand will be added at the
170 // back of the operand list.
171 static void AddOperand(DICompileUnit *CU, DISubprogramArray SPs,
173 SmallVector<Metadata *, 16> NewSPs;
174 NewSPs.reserve(SPs.size() + 1);
176 NewSPs.push_back(SP);
177 NewSPs.push_back(NewSP);
178 CU->replaceSubprograms(MDTuple::get(CU->getContext(), NewSPs));
181 // Clone the module-level debug info associated with OldFunc. The cloned data
182 // will point to NewFunc instead.
183 static void CloneDebugInfoMetadata(Function *NewFunc, const Function *OldFunc,
184 ValueToValueMapTy &VMap) {
185 DebugInfoFinder Finder;
186 Finder.processModule(*OldFunc->getParent());
188 const DISubprogram *OldSubprogramMDNode = FindSubprogram(OldFunc, Finder);
189 if (!OldSubprogramMDNode) return;
191 auto *NewSubprogram =
192 cast<DISubprogram>(MapMetadata(OldSubprogramMDNode, VMap));
193 NewFunc->setSubprogram(NewSubprogram);
195 for (auto *CU : Finder.compile_units()) {
196 auto Subprograms = CU->getSubprograms();
197 // If the compile unit's function list contains the old function, it should
198 // also contain the new one.
199 for (auto *SP : Subprograms) {
200 if (SP == OldSubprogramMDNode) {
201 AddOperand(CU, Subprograms, NewSubprogram);
208 /// Return a copy of the specified function, but without
209 /// embedding the function into another module. Also, any references specified
210 /// in the VMap are changed to refer to their mapped value instead of the
211 /// original one. If any of the arguments to the function are in the VMap,
212 /// the arguments are deleted from the resultant function. The VMap is
213 /// updated to include mappings from all of the instructions and basicblocks in
214 /// the function from their old to new values.
216 Function *llvm::CloneFunction(const Function *F, ValueToValueMapTy &VMap,
217 bool ModuleLevelChanges,
218 ClonedCodeInfo *CodeInfo) {
219 std::vector<Type*> ArgTypes;
221 // The user might be deleting arguments to the function by specifying them in
222 // the VMap. If so, we need to not add the arguments to the arg ty vector
224 for (const Argument &I : F->args())
225 if (VMap.count(&I) == 0) // Haven't mapped the argument to anything yet?
226 ArgTypes.push_back(I.getType());
228 // Create a new function type...
229 FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(),
230 ArgTypes, F->getFunctionType()->isVarArg());
232 // Create the new function...
233 Function *NewF = Function::Create(FTy, F->getLinkage(), F->getName());
235 // Loop over the arguments, copying the names of the mapped arguments over...
236 Function::arg_iterator DestI = NewF->arg_begin();
237 for (const Argument & I : F->args())
238 if (VMap.count(&I) == 0) { // Is this argument preserved?
239 DestI->setName(I.getName()); // Copy the name over...
240 VMap[&I] = &*DestI++; // Add mapping to VMap
243 if (ModuleLevelChanges)
244 CloneDebugInfoMetadata(NewF, F, VMap);
246 SmallVector<ReturnInst*, 8> Returns; // Ignore returns cloned.
247 CloneFunctionInto(NewF, F, VMap, ModuleLevelChanges, Returns, "", CodeInfo);
254 /// This is a private class used to implement CloneAndPruneFunctionInto.
255 struct PruningFunctionCloner {
257 const Function *OldFunc;
258 ValueToValueMapTy &VMap;
259 bool ModuleLevelChanges;
260 const char *NameSuffix;
261 ClonedCodeInfo *CodeInfo;
262 CloningDirector *Director;
263 ValueMapTypeRemapper *TypeMapper;
264 ValueMaterializer *Materializer;
267 PruningFunctionCloner(Function *newFunc, const Function *oldFunc,
268 ValueToValueMapTy &valueMap, bool moduleLevelChanges,
269 const char *nameSuffix, ClonedCodeInfo *codeInfo,
270 CloningDirector *Director)
271 : NewFunc(newFunc), OldFunc(oldFunc), VMap(valueMap),
272 ModuleLevelChanges(moduleLevelChanges), NameSuffix(nameSuffix),
273 CodeInfo(codeInfo), Director(Director) {
274 // These are optional components. The Director may return null.
276 TypeMapper = Director->getTypeRemapper();
277 Materializer = Director->getValueMaterializer();
279 TypeMapper = nullptr;
280 Materializer = nullptr;
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 WeakVH &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();
328 // If the "Director" remaps the instruction, don't clone it.
330 CloningDirector::CloningAction Action =
331 Director->handleInstruction(VMap, &*II, NewBB);
332 // If the cloning director says stop, we want to stop everything, not
333 // just break out of the loop (which would cause the terminator to be
334 // cloned). The cloning director is responsible for inserting a proper
335 // terminator into the new basic block in this case.
336 if (Action == CloningDirector::StopCloningBB)
338 // If the cloning director says skip, continue to the next instruction.
339 // In this case, the cloning director is responsible for mapping the
340 // skipped instruction to some value that is defined in the new
342 if (Action == CloningDirector::SkipInstruction)
346 Instruction *NewInst = II->clone();
348 // Eagerly remap operands to the newly cloned instruction, except for PHI
349 // nodes for which we defer processing until we update the CFG.
350 if (!isa<PHINode>(NewInst)) {
351 RemapInstruction(NewInst, VMap,
352 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
353 TypeMapper, Materializer);
355 // If we can simplify this instruction to some other value, simply add
356 // a mapping to that value rather than inserting a new instruction into
359 SimplifyInstruction(NewInst, BB->getModule()->getDataLayout())) {
360 // On the off-chance that this simplifies to an instruction in the old
361 // function, map it back into the new function.
362 if (Value *MappedV = VMap.lookup(V))
372 NewInst->setName(II->getName()+NameSuffix);
373 VMap[&*II] = NewInst; // Add instruction map to value.
374 NewBB->getInstList().push_back(NewInst);
375 hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
376 if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
377 if (isa<ConstantInt>(AI->getArraySize()))
378 hasStaticAllocas = true;
380 hasDynamicAllocas = true;
384 // Finally, clone over the terminator.
385 const TerminatorInst *OldTI = BB->getTerminator();
386 bool TerminatorDone = false;
388 CloningDirector::CloningAction Action
389 = Director->handleInstruction(VMap, OldTI, NewBB);
390 // If the cloning director says stop, we want to stop everything, not
391 // just break out of the loop (which would cause the terminator to be
392 // cloned). The cloning director is responsible for inserting a proper
393 // terminator into the new basic block in this case.
394 if (Action == CloningDirector::StopCloningBB)
396 if (Action == CloningDirector::CloneSuccessors) {
397 // If the director says to skip with a terminate instruction, we still
398 // need to clone this block's successors.
399 const TerminatorInst *TI = NewBB->getTerminator();
400 for (const BasicBlock *Succ : TI->successors())
401 ToClone.push_back(Succ);
404 assert(Action != CloningDirector::SkipInstruction &&
405 "SkipInstruction is not valid for terminators.");
407 if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) {
408 if (BI->isConditional()) {
409 // If the condition was a known constant in the callee...
410 ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
411 // Or is a known constant in the caller...
413 Value *V = VMap[BI->getCondition()];
414 Cond = dyn_cast_or_null<ConstantInt>(V);
417 // Constant fold to uncond branch!
419 BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue());
420 VMap[OldTI] = BranchInst::Create(Dest, NewBB);
421 ToClone.push_back(Dest);
422 TerminatorDone = true;
425 } else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) {
426 // If switching on a value known constant in the caller.
427 ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition());
428 if (!Cond) { // Or known constant after constant prop in the callee...
429 Value *V = VMap[SI->getCondition()];
430 Cond = dyn_cast_or_null<ConstantInt>(V);
432 if (Cond) { // Constant fold to uncond branch!
433 SwitchInst::ConstCaseIt Case = SI->findCaseValue(Cond);
434 BasicBlock *Dest = const_cast<BasicBlock*>(Case.getCaseSuccessor());
435 VMap[OldTI] = BranchInst::Create(Dest, NewBB);
436 ToClone.push_back(Dest);
437 TerminatorDone = true;
441 if (!TerminatorDone) {
442 Instruction *NewInst = OldTI->clone();
443 if (OldTI->hasName())
444 NewInst->setName(OldTI->getName()+NameSuffix);
445 NewBB->getInstList().push_back(NewInst);
446 VMap[OldTI] = NewInst; // Add instruction map to value.
448 // Recursively clone any reachable successor blocks.
449 const TerminatorInst *TI = BB->getTerminator();
450 for (const BasicBlock *Succ : TI->successors())
451 ToClone.push_back(Succ);
455 CodeInfo->ContainsCalls |= hasCalls;
456 CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
457 CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
458 BB != &BB->getParent()->front();
462 /// This works like CloneAndPruneFunctionInto, except that it does not clone the
463 /// entire function. Instead it starts at an instruction provided by the caller
464 /// and copies (and prunes) only the code reachable from that instruction.
465 void llvm::CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc,
466 const Instruction *StartingInst,
467 ValueToValueMapTy &VMap,
468 bool ModuleLevelChanges,
469 SmallVectorImpl<ReturnInst *> &Returns,
470 const char *NameSuffix,
471 ClonedCodeInfo *CodeInfo,
472 CloningDirector *Director) {
473 assert(NameSuffix && "NameSuffix cannot be null!");
475 ValueMapTypeRemapper *TypeMapper = nullptr;
476 ValueMaterializer *Materializer = nullptr;
479 TypeMapper = Director->getTypeRemapper();
480 Materializer = Director->getValueMaterializer();
484 // If the cloning starts at the beginning of the function, verify that
485 // the function arguments are mapped.
487 for (const Argument &II : OldFunc->args())
488 assert(VMap.count(&II) && "No mapping from source argument specified!");
491 PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges,
492 NameSuffix, CodeInfo, Director);
493 const BasicBlock *StartingBB;
495 StartingBB = StartingInst->getParent();
497 StartingBB = &OldFunc->getEntryBlock();
498 StartingInst = &StartingBB->front();
501 // Clone the entry block, and anything recursively reachable from it.
502 std::vector<const BasicBlock*> CloneWorklist;
503 PFC.CloneBlock(StartingBB, StartingInst->getIterator(), CloneWorklist);
504 while (!CloneWorklist.empty()) {
505 const BasicBlock *BB = CloneWorklist.back();
506 CloneWorklist.pop_back();
507 PFC.CloneBlock(BB, BB->begin(), CloneWorklist);
510 // Loop over all of the basic blocks in the old function. If the block was
511 // reachable, we have cloned it and the old block is now in the value map:
512 // insert it into the new function in the right order. If not, ignore it.
514 // Defer PHI resolution until rest of function is resolved.
515 SmallVector<const PHINode*, 16> PHIToResolve;
516 for (const BasicBlock &BI : *OldFunc) {
517 Value *V = VMap[&BI];
518 BasicBlock *NewBB = cast_or_null<BasicBlock>(V);
519 if (!NewBB) continue; // Dead block.
521 // Add the new block to the new function.
522 NewFunc->getBasicBlockList().push_back(NewBB);
524 // Handle PHI nodes specially, as we have to remove references to dead
526 for (BasicBlock::const_iterator I = BI.begin(), E = BI.end(); I != E; ++I) {
527 // PHI nodes may have been remapped to non-PHI nodes by the caller or
528 // during the cloning process.
529 if (const PHINode *PN = dyn_cast<PHINode>(I)) {
530 if (isa<PHINode>(VMap[PN]))
531 PHIToResolve.push_back(PN);
539 // Finally, remap the terminator instructions, as those can't be remapped
540 // until all BBs are mapped.
541 RemapInstruction(NewBB->getTerminator(), VMap,
542 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
543 TypeMapper, Materializer);
546 // Defer PHI resolution until rest of function is resolved, PHI resolution
547 // requires the CFG to be up-to-date.
548 for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
549 const PHINode *OPN = PHIToResolve[phino];
550 unsigned NumPreds = OPN->getNumIncomingValues();
551 const BasicBlock *OldBB = OPN->getParent();
552 BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]);
554 // Map operands for blocks that are live and remove operands for blocks
556 for (; phino != PHIToResolve.size() &&
557 PHIToResolve[phino]->getParent() == OldBB; ++phino) {
558 OPN = PHIToResolve[phino];
559 PHINode *PN = cast<PHINode>(VMap[OPN]);
560 for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
561 Value *V = VMap[PN->getIncomingBlock(pred)];
562 if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) {
563 Value *InVal = MapValue(PN->getIncomingValue(pred),
565 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
566 assert(InVal && "Unknown input value?");
567 PN->setIncomingValue(pred, InVal);
568 PN->setIncomingBlock(pred, MappedBlock);
570 PN->removeIncomingValue(pred, false);
571 --pred, --e; // Revisit the next entry.
576 // The loop above has removed PHI entries for those blocks that are dead
577 // and has updated others. However, if a block is live (i.e. copied over)
578 // but its terminator has been changed to not go to this block, then our
579 // phi nodes will have invalid entries. Update the PHI nodes in this
581 PHINode *PN = cast<PHINode>(NewBB->begin());
582 NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB));
583 if (NumPreds != PN->getNumIncomingValues()) {
584 assert(NumPreds < PN->getNumIncomingValues());
585 // Count how many times each predecessor comes to this block.
586 std::map<BasicBlock*, unsigned> PredCount;
587 for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
591 // Figure out how many entries to remove from each PHI.
592 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
593 ++PredCount[PN->getIncomingBlock(i)];
595 // At this point, the excess predecessor entries are positive in the
596 // map. Loop over all of the PHIs and remove excess predecessor
598 BasicBlock::iterator I = NewBB->begin();
599 for (; (PN = dyn_cast<PHINode>(I)); ++I) {
600 for (std::map<BasicBlock*, unsigned>::iterator PCI =PredCount.begin(),
601 E = PredCount.end(); PCI != E; ++PCI) {
602 BasicBlock *Pred = PCI->first;
603 for (unsigned NumToRemove = PCI->second; NumToRemove; --NumToRemove)
604 PN->removeIncomingValue(Pred, false);
609 // If the loops above have made these phi nodes have 0 or 1 operand,
610 // replace them with undef or the input value. We must do this for
611 // correctness, because 0-operand phis are not valid.
612 PN = cast<PHINode>(NewBB->begin());
613 if (PN->getNumIncomingValues() == 0) {
614 BasicBlock::iterator I = NewBB->begin();
615 BasicBlock::const_iterator OldI = OldBB->begin();
616 while ((PN = dyn_cast<PHINode>(I++))) {
617 Value *NV = UndefValue::get(PN->getType());
618 PN->replaceAllUsesWith(NV);
619 assert(VMap[&*OldI] == PN && "VMap mismatch");
621 PN->eraseFromParent();
627 // Make a second pass over the PHINodes now that all of them have been
628 // remapped into the new function, simplifying the PHINode and performing any
629 // recursive simplifications exposed. This will transparently update the
630 // WeakVH in the VMap. Notably, we rely on that so that if we coalesce
631 // two PHINodes, the iteration over the old PHIs remains valid, and the
632 // mapping will just map us to the new node (which may not even be a PHI
634 for (unsigned Idx = 0, Size = PHIToResolve.size(); Idx != Size; ++Idx)
635 if (PHINode *PN = dyn_cast<PHINode>(VMap[PHIToResolve[Idx]]))
636 recursivelySimplifyInstruction(PN);
638 // Now that the inlined function body has been fully constructed, go through
639 // and zap unconditional fall-through branches. This happens all the time when
640 // specializing code: code specialization turns conditional branches into
641 // uncond branches, and this code folds them.
642 Function::iterator Begin = cast<BasicBlock>(VMap[StartingBB])->getIterator();
643 Function::iterator I = Begin;
644 while (I != NewFunc->end()) {
645 // Check if this block has become dead during inlining or other
646 // simplifications. Note that the first block will appear dead, as it has
647 // not yet been wired up properly.
648 if (I != Begin && (pred_begin(&*I) == pred_end(&*I) ||
649 I->getSinglePredecessor() == &*I)) {
650 BasicBlock *DeadBB = &*I++;
651 DeleteDeadBlock(DeadBB);
655 // We need to simplify conditional branches and switches with a constant
656 // operand. We try to prune these out when cloning, but if the
657 // simplification required looking through PHI nodes, those are only
658 // available after forming the full basic block. That may leave some here,
659 // and we still want to prune the dead code as early as possible.
660 ConstantFoldTerminator(&*I);
662 BranchInst *BI = dyn_cast<BranchInst>(I->getTerminator());
663 if (!BI || BI->isConditional()) { ++I; continue; }
665 BasicBlock *Dest = BI->getSuccessor(0);
666 if (!Dest->getSinglePredecessor()) {
670 // We shouldn't be able to get single-entry PHI nodes here, as instsimplify
671 // above should have zapped all of them..
672 assert(!isa<PHINode>(Dest->begin()));
674 // We know all single-entry PHI nodes in the inlined function have been
675 // removed, so we just need to splice the blocks.
676 BI->eraseFromParent();
678 // Make all PHI nodes that referred to Dest now refer to I as their source.
679 Dest->replaceAllUsesWith(&*I);
681 // Move all the instructions in the succ to the pred.
682 I->getInstList().splice(I->end(), Dest->getInstList());
684 // Remove the dest block.
685 Dest->eraseFromParent();
687 // Do not increment I, iteratively merge all things this block branches to.
690 // Make a final pass over the basic blocks from the old function to gather
691 // any return instructions which survived folding. We have to do this here
692 // because we can iteratively remove and merge returns above.
693 for (Function::iterator I = cast<BasicBlock>(VMap[StartingBB])->getIterator(),
696 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator()))
697 Returns.push_back(RI);
701 /// This works exactly like CloneFunctionInto,
702 /// except that it does some simple constant prop and DCE on the fly. The
703 /// effect of this is to copy significantly less code in cases where (for
704 /// example) a function call with constant arguments is inlined, and those
705 /// constant arguments cause a significant amount of code in the callee to be
706 /// dead. Since this doesn't produce an exact copy of the input, it can't be
707 /// used for things like CloneFunction or CloneModule.
708 void llvm::CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
709 ValueToValueMapTy &VMap,
710 bool ModuleLevelChanges,
711 SmallVectorImpl<ReturnInst*> &Returns,
712 const char *NameSuffix,
713 ClonedCodeInfo *CodeInfo,
714 Instruction *TheCall) {
715 CloneAndPruneIntoFromInst(NewFunc, OldFunc, &OldFunc->front().front(), VMap,
716 ModuleLevelChanges, Returns, NameSuffix, CodeInfo,
720 /// \brief Remaps instructions in \p Blocks using the mapping in \p VMap.
721 void llvm::remapInstructionsInBlocks(
722 const SmallVectorImpl<BasicBlock *> &Blocks, ValueToValueMapTy &VMap) {
723 // Rewrite the code to refer to itself.
724 for (auto *BB : Blocks)
725 for (auto &Inst : *BB)
726 RemapInstruction(&Inst, VMap,
727 RF_NoModuleLevelChanges | RF_IgnoreMissingEntries);
730 /// \brief Clones a loop \p OrigLoop. Returns the loop and the blocks in \p
733 /// Updates LoopInfo and DominatorTree assuming the loop is dominated by block
734 /// \p LoopDomBB. Insert the new blocks before block specified in \p Before.
735 Loop *llvm::cloneLoopWithPreheader(BasicBlock *Before, BasicBlock *LoopDomBB,
736 Loop *OrigLoop, ValueToValueMapTy &VMap,
737 const Twine &NameSuffix, LoopInfo *LI,
739 SmallVectorImpl<BasicBlock *> &Blocks) {
740 Function *F = OrigLoop->getHeader()->getParent();
741 Loop *ParentLoop = OrigLoop->getParentLoop();
743 Loop *NewLoop = new Loop();
745 ParentLoop->addChildLoop(NewLoop);
747 LI->addTopLevelLoop(NewLoop);
749 BasicBlock *OrigPH = OrigLoop->getLoopPreheader();
750 assert(OrigPH && "No preheader");
751 BasicBlock *NewPH = CloneBasicBlock(OrigPH, VMap, NameSuffix, F);
752 // To rename the loop PHIs.
753 VMap[OrigPH] = NewPH;
754 Blocks.push_back(NewPH);
758 ParentLoop->addBasicBlockToLoop(NewPH, *LI);
760 // Update DominatorTree.
761 DT->addNewBlock(NewPH, LoopDomBB);
763 for (BasicBlock *BB : OrigLoop->getBlocks()) {
764 BasicBlock *NewBB = CloneBasicBlock(BB, VMap, NameSuffix, F);
768 NewLoop->addBasicBlockToLoop(NewBB, *LI);
770 // Update DominatorTree.
771 BasicBlock *IDomBB = DT->getNode(BB)->getIDom()->getBlock();
772 DT->addNewBlock(NewBB, cast<BasicBlock>(VMap[IDomBB]));
774 Blocks.push_back(NewBB);
777 // Move them physically from the end of the block list.
778 F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(),
780 F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(),
781 NewLoop->getHeader()->getIterator(), F->end());