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 // Ensure that OldFunc appears in the map.
192 // (if it's already there it must point to NewFunc anyway)
193 VMap[OldFunc] = NewFunc;
194 auto *NewSubprogram =
195 cast<DISubprogram>(MapMetadata(OldSubprogramMDNode, VMap));
197 for (auto *CU : Finder.compile_units()) {
198 auto Subprograms = CU->getSubprograms();
199 // If the compile unit's function list contains the old function, it should
200 // also contain the new one.
201 for (auto *SP : Subprograms) {
202 if (SP == OldSubprogramMDNode) {
203 AddOperand(CU, Subprograms, NewSubprogram);
210 /// Return a copy of the specified function, but without
211 /// embedding the function into another module. Also, any references specified
212 /// in the VMap are changed to refer to their mapped value instead of the
213 /// original one. If any of the arguments to the function are in the VMap,
214 /// the arguments are deleted from the resultant function. The VMap is
215 /// updated to include mappings from all of the instructions and basicblocks in
216 /// the function from their old to new values.
218 Function *llvm::CloneFunction(const Function *F, ValueToValueMapTy &VMap,
219 bool ModuleLevelChanges,
220 ClonedCodeInfo *CodeInfo) {
221 std::vector<Type*> ArgTypes;
223 // The user might be deleting arguments to the function by specifying them in
224 // the VMap. If so, we need to not add the arguments to the arg ty vector
226 for (const Argument &I : F->args())
227 if (VMap.count(&I) == 0) // Haven't mapped the argument to anything yet?
228 ArgTypes.push_back(I.getType());
230 // Create a new function type...
231 FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(),
232 ArgTypes, F->getFunctionType()->isVarArg());
234 // Create the new function...
235 Function *NewF = Function::Create(FTy, F->getLinkage(), F->getName());
237 // Loop over the arguments, copying the names of the mapped arguments over...
238 Function::arg_iterator DestI = NewF->arg_begin();
239 for (const Argument & I : F->args())
240 if (VMap.count(&I) == 0) { // Is this argument preserved?
241 DestI->setName(I.getName()); // Copy the name over...
242 VMap[&I] = &*DestI++; // Add mapping to VMap
245 if (ModuleLevelChanges)
246 CloneDebugInfoMetadata(NewF, F, VMap);
248 SmallVector<ReturnInst*, 8> Returns; // Ignore returns cloned.
249 CloneFunctionInto(NewF, F, VMap, ModuleLevelChanges, Returns, "", CodeInfo);
256 /// This is a private class used to implement CloneAndPruneFunctionInto.
257 struct PruningFunctionCloner {
259 const Function *OldFunc;
260 ValueToValueMapTy &VMap;
261 bool ModuleLevelChanges;
262 const char *NameSuffix;
263 ClonedCodeInfo *CodeInfo;
264 CloningDirector *Director;
265 ValueMapTypeRemapper *TypeMapper;
266 ValueMaterializer *Materializer;
269 PruningFunctionCloner(Function *newFunc, const Function *oldFunc,
270 ValueToValueMapTy &valueMap, bool moduleLevelChanges,
271 const char *nameSuffix, ClonedCodeInfo *codeInfo,
272 CloningDirector *Director)
273 : NewFunc(newFunc), OldFunc(oldFunc), VMap(valueMap),
274 ModuleLevelChanges(moduleLevelChanges), NameSuffix(nameSuffix),
275 CodeInfo(codeInfo), Director(Director) {
276 // These are optional components. The Director may return null.
278 TypeMapper = Director->getTypeRemapper();
279 Materializer = Director->getValueMaterializer();
281 TypeMapper = nullptr;
282 Materializer = nullptr;
286 /// The specified block is found to be reachable, clone it and
287 /// anything that it can reach.
288 void CloneBlock(const BasicBlock *BB,
289 BasicBlock::const_iterator StartingInst,
290 std::vector<const BasicBlock*> &ToClone);
294 /// The specified block is found to be reachable, clone it and
295 /// anything that it can reach.
296 void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
297 BasicBlock::const_iterator StartingInst,
298 std::vector<const BasicBlock*> &ToClone){
299 WeakVH &BBEntry = VMap[BB];
301 // Have we already cloned this block?
304 // Nope, clone it now.
306 BBEntry = NewBB = BasicBlock::Create(BB->getContext());
307 if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
309 // It is only legal to clone a function if a block address within that
310 // function is never referenced outside of the function. Given that, we
311 // want to map block addresses from the old function to block addresses in
312 // the clone. (This is different from the generic ValueMapper
313 // implementation, which generates an invalid blockaddress when
314 // cloning a function.)
316 // Note that we don't need to fix the mapping for unreachable blocks;
317 // the default mapping there is safe.
318 if (BB->hasAddressTaken()) {
319 Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
320 const_cast<BasicBlock*>(BB));
321 VMap[OldBBAddr] = BlockAddress::get(NewFunc, NewBB);
324 bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
326 // Loop over all instructions, and copy them over, DCE'ing as we go. This
327 // loop doesn't include the terminator.
328 for (BasicBlock::const_iterator II = StartingInst, IE = --BB->end();
330 // If the "Director" remaps the instruction, don't clone it.
332 CloningDirector::CloningAction Action =
333 Director->handleInstruction(VMap, &*II, NewBB);
334 // If the cloning director says stop, we want to stop everything, not
335 // just break out of the loop (which would cause the terminator to be
336 // cloned). The cloning director is responsible for inserting a proper
337 // terminator into the new basic block in this case.
338 if (Action == CloningDirector::StopCloningBB)
340 // If the cloning director says skip, continue to the next instruction.
341 // In this case, the cloning director is responsible for mapping the
342 // skipped instruction to some value that is defined in the new
344 if (Action == CloningDirector::SkipInstruction)
348 Instruction *NewInst = II->clone();
350 // Eagerly remap operands to the newly cloned instruction, except for PHI
351 // nodes for which we defer processing until we update the CFG.
352 if (!isa<PHINode>(NewInst)) {
353 RemapInstruction(NewInst, VMap,
354 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
355 TypeMapper, Materializer);
357 // If we can simplify this instruction to some other value, simply add
358 // a mapping to that value rather than inserting a new instruction into
361 SimplifyInstruction(NewInst, BB->getModule()->getDataLayout())) {
362 // On the off-chance that this simplifies to an instruction in the old
363 // function, map it back into the new function.
364 if (Value *MappedV = VMap.lookup(V))
374 NewInst->setName(II->getName()+NameSuffix);
375 VMap[&*II] = NewInst; // Add instruction map to value.
376 NewBB->getInstList().push_back(NewInst);
377 hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
378 if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
379 if (isa<ConstantInt>(AI->getArraySize()))
380 hasStaticAllocas = true;
382 hasDynamicAllocas = true;
386 // Finally, clone over the terminator.
387 const TerminatorInst *OldTI = BB->getTerminator();
388 bool TerminatorDone = false;
390 CloningDirector::CloningAction Action
391 = Director->handleInstruction(VMap, OldTI, NewBB);
392 // If the cloning director says stop, we want to stop everything, not
393 // just break out of the loop (which would cause the terminator to be
394 // cloned). The cloning director is responsible for inserting a proper
395 // terminator into the new basic block in this case.
396 if (Action == CloningDirector::StopCloningBB)
398 if (Action == CloningDirector::CloneSuccessors) {
399 // If the director says to skip with a terminate instruction, we still
400 // need to clone this block's successors.
401 const TerminatorInst *TI = NewBB->getTerminator();
402 for (const BasicBlock *Succ : TI->successors())
403 ToClone.push_back(Succ);
406 assert(Action != CloningDirector::SkipInstruction &&
407 "SkipInstruction is not valid for terminators.");
409 if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) {
410 if (BI->isConditional()) {
411 // If the condition was a known constant in the callee...
412 ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
413 // Or is a known constant in the caller...
415 Value *V = VMap[BI->getCondition()];
416 Cond = dyn_cast_or_null<ConstantInt>(V);
419 // Constant fold to uncond branch!
421 BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue());
422 VMap[OldTI] = BranchInst::Create(Dest, NewBB);
423 ToClone.push_back(Dest);
424 TerminatorDone = true;
427 } else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) {
428 // If switching on a value known constant in the caller.
429 ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition());
430 if (!Cond) { // Or known constant after constant prop in the callee...
431 Value *V = VMap[SI->getCondition()];
432 Cond = dyn_cast_or_null<ConstantInt>(V);
434 if (Cond) { // Constant fold to uncond branch!
435 SwitchInst::ConstCaseIt Case = SI->findCaseValue(Cond);
436 BasicBlock *Dest = const_cast<BasicBlock*>(Case.getCaseSuccessor());
437 VMap[OldTI] = BranchInst::Create(Dest, NewBB);
438 ToClone.push_back(Dest);
439 TerminatorDone = true;
443 if (!TerminatorDone) {
444 Instruction *NewInst = OldTI->clone();
445 if (OldTI->hasName())
446 NewInst->setName(OldTI->getName()+NameSuffix);
447 NewBB->getInstList().push_back(NewInst);
448 VMap[OldTI] = NewInst; // Add instruction map to value.
450 // Recursively clone any reachable successor blocks.
451 const TerminatorInst *TI = BB->getTerminator();
452 for (const BasicBlock *Succ : TI->successors())
453 ToClone.push_back(Succ);
457 CodeInfo->ContainsCalls |= hasCalls;
458 CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
459 CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
460 BB != &BB->getParent()->front();
464 /// This works like CloneAndPruneFunctionInto, except that it does not clone the
465 /// entire function. Instead it starts at an instruction provided by the caller
466 /// and copies (and prunes) only the code reachable from that instruction.
467 void llvm::CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc,
468 const Instruction *StartingInst,
469 ValueToValueMapTy &VMap,
470 bool ModuleLevelChanges,
471 SmallVectorImpl<ReturnInst *> &Returns,
472 const char *NameSuffix,
473 ClonedCodeInfo *CodeInfo,
474 CloningDirector *Director) {
475 assert(NameSuffix && "NameSuffix cannot be null!");
477 ValueMapTypeRemapper *TypeMapper = nullptr;
478 ValueMaterializer *Materializer = nullptr;
481 TypeMapper = Director->getTypeRemapper();
482 Materializer = Director->getValueMaterializer();
486 // If the cloning starts at the beginning of the function, verify that
487 // the function arguments are mapped.
489 for (const Argument &II : OldFunc->args())
490 assert(VMap.count(&II) && "No mapping from source argument specified!");
493 PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges,
494 NameSuffix, CodeInfo, Director);
495 const BasicBlock *StartingBB;
497 StartingBB = StartingInst->getParent();
499 StartingBB = &OldFunc->getEntryBlock();
500 StartingInst = &StartingBB->front();
503 // Clone the entry block, and anything recursively reachable from it.
504 std::vector<const BasicBlock*> CloneWorklist;
505 PFC.CloneBlock(StartingBB, StartingInst->getIterator(), CloneWorklist);
506 while (!CloneWorklist.empty()) {
507 const BasicBlock *BB = CloneWorklist.back();
508 CloneWorklist.pop_back();
509 PFC.CloneBlock(BB, BB->begin(), CloneWorklist);
512 // Loop over all of the basic blocks in the old function. If the block was
513 // reachable, we have cloned it and the old block is now in the value map:
514 // insert it into the new function in the right order. If not, ignore it.
516 // Defer PHI resolution until rest of function is resolved.
517 SmallVector<const PHINode*, 16> PHIToResolve;
518 for (const BasicBlock &BI : *OldFunc) {
519 Value *V = VMap[&BI];
520 BasicBlock *NewBB = cast_or_null<BasicBlock>(V);
521 if (!NewBB) continue; // Dead block.
523 // Add the new block to the new function.
524 NewFunc->getBasicBlockList().push_back(NewBB);
526 // Handle PHI nodes specially, as we have to remove references to dead
528 for (BasicBlock::const_iterator I = BI.begin(), E = BI.end(); I != E; ++I) {
529 // PHI nodes may have been remapped to non-PHI nodes by the caller or
530 // during the cloning process.
531 if (const PHINode *PN = dyn_cast<PHINode>(I)) {
532 if (isa<PHINode>(VMap[PN]))
533 PHIToResolve.push_back(PN);
541 // Finally, remap the terminator instructions, as those can't be remapped
542 // until all BBs are mapped.
543 RemapInstruction(NewBB->getTerminator(), VMap,
544 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
545 TypeMapper, Materializer);
548 // Defer PHI resolution until rest of function is resolved, PHI resolution
549 // requires the CFG to be up-to-date.
550 for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
551 const PHINode *OPN = PHIToResolve[phino];
552 unsigned NumPreds = OPN->getNumIncomingValues();
553 const BasicBlock *OldBB = OPN->getParent();
554 BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]);
556 // Map operands for blocks that are live and remove operands for blocks
558 for (; phino != PHIToResolve.size() &&
559 PHIToResolve[phino]->getParent() == OldBB; ++phino) {
560 OPN = PHIToResolve[phino];
561 PHINode *PN = cast<PHINode>(VMap[OPN]);
562 for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
563 Value *V = VMap[PN->getIncomingBlock(pred)];
564 if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) {
565 Value *InVal = MapValue(PN->getIncomingValue(pred),
567 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
568 assert(InVal && "Unknown input value?");
569 PN->setIncomingValue(pred, InVal);
570 PN->setIncomingBlock(pred, MappedBlock);
572 PN->removeIncomingValue(pred, false);
573 --pred, --e; // Revisit the next entry.
578 // The loop above has removed PHI entries for those blocks that are dead
579 // and has updated others. However, if a block is live (i.e. copied over)
580 // but its terminator has been changed to not go to this block, then our
581 // phi nodes will have invalid entries. Update the PHI nodes in this
583 PHINode *PN = cast<PHINode>(NewBB->begin());
584 NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB));
585 if (NumPreds != PN->getNumIncomingValues()) {
586 assert(NumPreds < PN->getNumIncomingValues());
587 // Count how many times each predecessor comes to this block.
588 std::map<BasicBlock*, unsigned> PredCount;
589 for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
593 // Figure out how many entries to remove from each PHI.
594 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
595 ++PredCount[PN->getIncomingBlock(i)];
597 // At this point, the excess predecessor entries are positive in the
598 // map. Loop over all of the PHIs and remove excess predecessor
600 BasicBlock::iterator I = NewBB->begin();
601 for (; (PN = dyn_cast<PHINode>(I)); ++I) {
602 for (std::map<BasicBlock*, unsigned>::iterator PCI =PredCount.begin(),
603 E = PredCount.end(); PCI != E; ++PCI) {
604 BasicBlock *Pred = PCI->first;
605 for (unsigned NumToRemove = PCI->second; NumToRemove; --NumToRemove)
606 PN->removeIncomingValue(Pred, false);
611 // If the loops above have made these phi nodes have 0 or 1 operand,
612 // replace them with undef or the input value. We must do this for
613 // correctness, because 0-operand phis are not valid.
614 PN = cast<PHINode>(NewBB->begin());
615 if (PN->getNumIncomingValues() == 0) {
616 BasicBlock::iterator I = NewBB->begin();
617 BasicBlock::const_iterator OldI = OldBB->begin();
618 while ((PN = dyn_cast<PHINode>(I++))) {
619 Value *NV = UndefValue::get(PN->getType());
620 PN->replaceAllUsesWith(NV);
621 assert(VMap[&*OldI] == PN && "VMap mismatch");
623 PN->eraseFromParent();
629 // Make a second pass over the PHINodes now that all of them have been
630 // remapped into the new function, simplifying the PHINode and performing any
631 // recursive simplifications exposed. This will transparently update the
632 // WeakVH in the VMap. Notably, we rely on that so that if we coalesce
633 // two PHINodes, the iteration over the old PHIs remains valid, and the
634 // mapping will just map us to the new node (which may not even be a PHI
636 for (unsigned Idx = 0, Size = PHIToResolve.size(); Idx != Size; ++Idx)
637 if (PHINode *PN = dyn_cast<PHINode>(VMap[PHIToResolve[Idx]]))
638 recursivelySimplifyInstruction(PN);
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,
722 /// \brief Remaps instructions in \p Blocks using the mapping in \p VMap.
723 void llvm::remapInstructionsInBlocks(
724 const SmallVectorImpl<BasicBlock *> &Blocks, ValueToValueMapTy &VMap) {
725 // Rewrite the code to refer to itself.
726 for (auto *BB : Blocks)
727 for (auto &Inst : *BB)
728 RemapInstruction(&Inst, VMap,
729 RF_NoModuleLevelChanges | RF_IgnoreMissingEntries);
732 /// \brief Clones a loop \p OrigLoop. Returns the loop and the blocks in \p
735 /// Updates LoopInfo and DominatorTree assuming the loop is dominated by block
736 /// \p LoopDomBB. Insert the new blocks before block specified in \p Before.
737 Loop *llvm::cloneLoopWithPreheader(BasicBlock *Before, BasicBlock *LoopDomBB,
738 Loop *OrigLoop, ValueToValueMapTy &VMap,
739 const Twine &NameSuffix, LoopInfo *LI,
741 SmallVectorImpl<BasicBlock *> &Blocks) {
742 Function *F = OrigLoop->getHeader()->getParent();
743 Loop *ParentLoop = OrigLoop->getParentLoop();
745 Loop *NewLoop = new Loop();
747 ParentLoop->addChildLoop(NewLoop);
749 LI->addTopLevelLoop(NewLoop);
751 BasicBlock *OrigPH = OrigLoop->getLoopPreheader();
752 assert(OrigPH && "No preheader");
753 BasicBlock *NewPH = CloneBasicBlock(OrigPH, VMap, NameSuffix, F);
754 // To rename the loop PHIs.
755 VMap[OrigPH] = NewPH;
756 Blocks.push_back(NewPH);
760 ParentLoop->addBasicBlockToLoop(NewPH, *LI);
762 // Update DominatorTree.
763 DT->addNewBlock(NewPH, LoopDomBB);
765 for (BasicBlock *BB : OrigLoop->getBlocks()) {
766 BasicBlock *NewBB = CloneBasicBlock(BB, VMap, NameSuffix, F);
770 NewLoop->addBasicBlockToLoop(NewBB, *LI);
772 // Update DominatorTree.
773 BasicBlock *IDomBB = DT->getNode(BB)->getIDom()->getBlock();
774 DT->addNewBlock(NewBB, cast<BasicBlock>(VMap[IDomBB]));
776 Blocks.push_back(NewBB);
779 // Move them physically from the end of the block list.
780 F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(),
782 F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(),
783 NewLoop->getHeader()->getIterator(), F->end());