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/IR/CFG.h"
21 #include "llvm/IR/Constants.h"
22 #include "llvm/IR/DebugInfo.h"
23 #include "llvm/IR/DerivedTypes.h"
24 #include "llvm/IR/Function.h"
25 #include "llvm/IR/GlobalVariable.h"
26 #include "llvm/IR/Instructions.h"
27 #include "llvm/IR/IntrinsicInst.h"
28 #include "llvm/IR/LLVMContext.h"
29 #include "llvm/IR/Metadata.h"
30 #include "llvm/IR/Module.h"
31 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
32 #include "llvm/Transforms/Utils/Local.h"
33 #include "llvm/Transforms/Utils/ValueMapper.h"
37 // CloneBasicBlock - See comments in Cloning.h
38 BasicBlock *llvm::CloneBasicBlock(const BasicBlock *BB,
39 ValueToValueMapTy &VMap,
40 const Twine &NameSuffix, Function *F,
41 ClonedCodeInfo *CodeInfo) {
42 BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "", F);
43 if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
45 bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
47 // Loop over all instructions, and copy them over.
48 for (BasicBlock::const_iterator II = BB->begin(), IE = BB->end();
50 Instruction *NewInst = II->clone();
52 NewInst->setName(II->getName()+NameSuffix);
53 NewBB->getInstList().push_back(NewInst);
54 VMap[II] = NewInst; // Add instruction map to value.
56 hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
57 if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
58 if (isa<ConstantInt>(AI->getArraySize()))
59 hasStaticAllocas = true;
61 hasDynamicAllocas = true;
66 CodeInfo->ContainsCalls |= hasCalls;
67 CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
68 CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
69 BB != &BB->getParent()->getEntryBlock();
74 // Clone OldFunc into NewFunc, transforming the old arguments into references to
77 void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
78 ValueToValueMapTy &VMap,
79 bool ModuleLevelChanges,
80 SmallVectorImpl<ReturnInst*> &Returns,
81 const char *NameSuffix, ClonedCodeInfo *CodeInfo,
82 ValueMapTypeRemapper *TypeMapper,
83 ValueMaterializer *Materializer) {
84 assert(NameSuffix && "NameSuffix cannot be null!");
87 for (Function::const_arg_iterator I = OldFunc->arg_begin(),
88 E = OldFunc->arg_end(); I != E; ++I)
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 = cast<BasicBlock>(VMap[OldFunc->begin()]),
149 BE = NewFunc->end(); BB != BE; ++BB)
150 // Loop over all instructions, fixing each one as we find it...
151 for (BasicBlock::iterator II = BB->begin(); II != BB->end(); ++II)
152 RemapInstruction(II, VMap,
153 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
154 TypeMapper, Materializer);
157 // Find the MDNode which corresponds to the DISubprogram data that described F.
158 static MDNode* FindSubprogram(const Function *F, DebugInfoFinder &Finder) {
159 for (DISubprogram Subprogram : Finder.subprograms()) {
160 if (Subprogram.describes(F)) return Subprogram;
165 // Add an operand to an existing MDNode. The new operand will be added at the
166 // back of the operand list.
167 static void AddOperand(DICompileUnit CU, DIArray SPs, Metadata *NewSP) {
168 SmallVector<Metadata *, 16> NewSPs;
169 NewSPs.reserve(SPs->getNumOperands() + 1);
170 for (unsigned I = 0, E = SPs->getNumOperands(); I != E; ++I)
171 NewSPs.push_back(SPs->getOperand(I));
172 NewSPs.push_back(NewSP);
173 CU.replaceSubprograms(DIArray(MDNode::get(CU->getContext(), NewSPs)));
176 // Clone the module-level debug info associated with OldFunc. The cloned data
177 // will point to NewFunc instead.
178 static void CloneDebugInfoMetadata(Function *NewFunc, const Function *OldFunc,
179 ValueToValueMapTy &VMap) {
180 DebugInfoFinder Finder;
181 Finder.processModule(*OldFunc->getParent());
183 const MDNode *OldSubprogramMDNode = FindSubprogram(OldFunc, Finder);
184 if (!OldSubprogramMDNode) return;
186 // Ensure that OldFunc appears in the map.
187 // (if it's already there it must point to NewFunc anyway)
188 VMap[OldFunc] = NewFunc;
189 DISubprogram NewSubprogram(MapMetadata(OldSubprogramMDNode, VMap));
191 for (DICompileUnit CU : Finder.compile_units()) {
192 DIArray Subprograms(CU.getSubprograms());
194 // If the compile unit's function list contains the old function, it should
195 // also contain the new one.
196 for (unsigned i = 0; i < Subprograms.getNumElements(); i++) {
197 if ((MDNode*)Subprograms.getElement(i) == OldSubprogramMDNode) {
198 AddOperand(CU, Subprograms, NewSubprogram);
205 /// CloneFunction - Return a copy of the specified function, but without
206 /// embedding the function into another module. Also, any references specified
207 /// in the VMap are changed to refer to their mapped value instead of the
208 /// original one. If any of the arguments to the function are in the VMap,
209 /// the arguments are deleted from the resultant function. The VMap is
210 /// updated to include mappings from all of the instructions and basicblocks in
211 /// the function from their old to new values.
213 Function *llvm::CloneFunction(const Function *F, ValueToValueMapTy &VMap,
214 bool ModuleLevelChanges,
215 ClonedCodeInfo *CodeInfo) {
216 std::vector<Type*> ArgTypes;
218 // The user might be deleting arguments to the function by specifying them in
219 // the VMap. If so, we need to not add the arguments to the arg ty vector
221 for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
223 if (VMap.count(I) == 0) // Haven't mapped the argument to anything yet?
224 ArgTypes.push_back(I->getType());
226 // Create a new function type...
227 FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(),
228 ArgTypes, F->getFunctionType()->isVarArg());
230 // Create the new function...
231 Function *NewF = Function::Create(FTy, F->getLinkage(), F->getName());
233 // Loop over the arguments, copying the names of the mapped arguments over...
234 Function::arg_iterator DestI = NewF->arg_begin();
235 for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
237 if (VMap.count(I) == 0) { // Is this argument preserved?
238 DestI->setName(I->getName()); // Copy the name over...
239 VMap[I] = DestI++; // Add mapping to VMap
242 if (ModuleLevelChanges)
243 CloneDebugInfoMetadata(NewF, F, VMap);
245 SmallVector<ReturnInst*, 8> Returns; // Ignore returns cloned.
246 CloneFunctionInto(NewF, F, VMap, ModuleLevelChanges, Returns, "", CodeInfo);
253 /// PruningFunctionCloner - This class is a private class used to implement
254 /// the CloneAndPruneFunctionInto method.
255 struct PruningFunctionCloner {
257 const Function *OldFunc;
258 ValueToValueMapTy &VMap;
259 bool ModuleLevelChanges;
260 const char *NameSuffix;
261 ClonedCodeInfo *CodeInfo;
262 const DataLayout *DL;
263 CloningDirector *Director;
264 ValueMapTypeRemapper *TypeMapper;
265 ValueMaterializer *Materializer;
268 PruningFunctionCloner(Function *newFunc, const Function *oldFunc,
269 ValueToValueMapTy &valueMap,
270 bool moduleLevelChanges,
271 const char *nameSuffix,
272 ClonedCodeInfo *codeInfo,
273 const DataLayout *DL,
274 CloningDirector *Director)
275 : NewFunc(newFunc), OldFunc(oldFunc),
276 VMap(valueMap), ModuleLevelChanges(moduleLevelChanges),
277 NameSuffix(nameSuffix), CodeInfo(codeInfo), DL(DL),
279 // These are optional components. The Director may return null.
281 TypeMapper = Director->getTypeRemapper();
282 Materializer = Director->getValueMaterializer();
284 TypeMapper = nullptr;
285 Materializer = nullptr;
289 /// CloneBlock - The specified block is found to be reachable, clone it and
290 /// anything that it can reach.
291 void CloneBlock(const BasicBlock *BB,
292 BasicBlock::const_iterator StartingInst,
293 std::vector<const BasicBlock*> &ToClone);
297 /// CloneBlock - The specified block is found to be reachable, clone it and
298 /// anything that it can reach.
299 void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
300 BasicBlock::const_iterator StartingInst,
301 std::vector<const BasicBlock*> &ToClone){
302 WeakVH &BBEntry = VMap[BB];
304 // Have we already cloned this block?
307 // Nope, clone it now.
309 BBEntry = NewBB = BasicBlock::Create(BB->getContext());
310 if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
312 // It is only legal to clone a function if a block address within that
313 // function is never referenced outside of the function. Given that, we
314 // want to map block addresses from the old function to block addresses in
315 // the clone. (This is different from the generic ValueMapper
316 // implementation, which generates an invalid blockaddress when
317 // cloning a function.)
319 // Note that we don't need to fix the mapping for unreachable blocks;
320 // the default mapping there is safe.
321 if (BB->hasAddressTaken()) {
322 Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
323 const_cast<BasicBlock*>(BB));
324 VMap[OldBBAddr] = BlockAddress::get(NewFunc, NewBB);
327 bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
329 // Loop over all instructions, and copy them over, DCE'ing as we go. This
330 // loop doesn't include the terminator.
331 for (BasicBlock::const_iterator II = StartingInst, IE = --BB->end();
333 // If the "Director" remaps the instruction, don't clone it.
335 CloningDirector::CloningAction Action
336 = Director->handleInstruction(VMap, II, NewBB);
337 // If the cloning director says stop, we want to stop everything, not
338 // just break out of the loop (which would cause the terminator to be
339 // cloned). The cloning director is responsible for inserting a proper
340 // terminator into the new basic block in this case.
341 if (Action == CloningDirector::StopCloningBB)
343 // If the cloning director says skip, continue to the next instruction.
344 // In this case, the cloning director is responsible for mapping the
345 // skipped instruction to some value that is defined in the new
347 if (Action == CloningDirector::SkipInstruction)
351 Instruction *NewInst = II->clone();
353 // Eagerly remap operands to the newly cloned instruction, except for PHI
354 // nodes for which we defer processing until we update the CFG.
355 if (!isa<PHINode>(NewInst)) {
356 RemapInstruction(NewInst, VMap,
357 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
358 TypeMapper, Materializer);
360 // If we can simplify this instruction to some other value, simply add
361 // a mapping to that value rather than inserting a new instruction into
363 if (Value *V = SimplifyInstruction(NewInst, DL)) {
364 // On the off-chance that this simplifies to an instruction in the old
365 // function, map it back into the new function.
366 if (Value *MappedV = VMap.lookup(V))
376 NewInst->setName(II->getName()+NameSuffix);
377 VMap[II] = NewInst; // Add instruction map to value.
378 NewBB->getInstList().push_back(NewInst);
379 hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
380 if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
381 if (isa<ConstantInt>(AI->getArraySize()))
382 hasStaticAllocas = true;
384 hasDynamicAllocas = true;
388 // Finally, clone over the terminator.
389 const TerminatorInst *OldTI = BB->getTerminator();
390 bool TerminatorDone = false;
392 CloningDirector::CloningAction Action
393 = Director->handleInstruction(VMap, OldTI, NewBB);
394 // If the cloning director says stop, we want to stop everything, not
395 // just break out of the loop (which would cause the terminator to be
396 // cloned). The cloning director is responsible for inserting a proper
397 // terminator into the new basic block in this case.
398 if (Action == CloningDirector::StopCloningBB)
400 assert(Action != CloningDirector::SkipInstruction &&
401 "SkipInstruction is not valid for terminators.");
403 if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) {
404 if (BI->isConditional()) {
405 // If the condition was a known constant in the callee...
406 ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
407 // Or is a known constant in the caller...
409 Value *V = VMap[BI->getCondition()];
410 Cond = dyn_cast_or_null<ConstantInt>(V);
413 // Constant fold to uncond branch!
415 BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue());
416 VMap[OldTI] = BranchInst::Create(Dest, NewBB);
417 ToClone.push_back(Dest);
418 TerminatorDone = true;
421 } else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) {
422 // If switching on a value known constant in the caller.
423 ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition());
424 if (!Cond) { // Or known constant after constant prop in the callee...
425 Value *V = VMap[SI->getCondition()];
426 Cond = dyn_cast_or_null<ConstantInt>(V);
428 if (Cond) { // Constant fold to uncond branch!
429 SwitchInst::ConstCaseIt Case = SI->findCaseValue(Cond);
430 BasicBlock *Dest = const_cast<BasicBlock*>(Case.getCaseSuccessor());
431 VMap[OldTI] = BranchInst::Create(Dest, NewBB);
432 ToClone.push_back(Dest);
433 TerminatorDone = true;
437 if (!TerminatorDone) {
438 Instruction *NewInst = OldTI->clone();
439 if (OldTI->hasName())
440 NewInst->setName(OldTI->getName()+NameSuffix);
441 NewBB->getInstList().push_back(NewInst);
442 VMap[OldTI] = NewInst; // Add instruction map to value.
444 // Recursively clone any reachable successor blocks.
445 const TerminatorInst *TI = BB->getTerminator();
446 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
447 ToClone.push_back(TI->getSuccessor(i));
451 CodeInfo->ContainsCalls |= hasCalls;
452 CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
453 CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
454 BB != &BB->getParent()->front();
458 /// CloneAndPruneIntoFromInst - This works like CloneAndPruneFunctionInto, except
459 /// that it does not clone the entire function. Instead it starts at an
460 /// instruction provided by the caller and copies (and prunes) only the code
461 /// reachable from that instruction.
462 void llvm::CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc,
463 const Instruction *StartingInst,
464 ValueToValueMapTy &VMap,
465 bool ModuleLevelChanges,
466 SmallVectorImpl<ReturnInst *> &Returns,
467 const char *NameSuffix,
468 ClonedCodeInfo *CodeInfo,
469 const DataLayout *DL,
470 CloningDirector *Director) {
471 assert(NameSuffix && "NameSuffix cannot be null!");
473 ValueMapTypeRemapper *TypeMapper = nullptr;
474 ValueMaterializer *Materializer = nullptr;
477 TypeMapper = Director->getTypeRemapper();
478 Materializer = Director->getValueMaterializer();
482 // If the cloning starts at the begining of the function, verify that
483 // the function arguments are mapped.
485 for (Function::const_arg_iterator II = OldFunc->arg_begin(),
486 E = OldFunc->arg_end(); II != E; ++II)
487 assert(VMap.count(II) && "No mapping from source argument specified!");
490 PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges,
491 NameSuffix, CodeInfo, DL, Director);
492 const BasicBlock *StartingBB;
494 StartingBB = StartingInst->getParent();
496 StartingBB = &OldFunc->getEntryBlock();
497 StartingInst = StartingBB->begin();
500 // Clone the entry block, and anything recursively reachable from it.
501 std::vector<const BasicBlock*> CloneWorklist;
502 PFC.CloneBlock(StartingBB, StartingInst, CloneWorklist);
503 while (!CloneWorklist.empty()) {
504 const BasicBlock *BB = CloneWorklist.back();
505 CloneWorklist.pop_back();
506 PFC.CloneBlock(BB, BB->begin(), CloneWorklist);
509 // Loop over all of the basic blocks in the old function. If the block was
510 // reachable, we have cloned it and the old block is now in the value map:
511 // insert it into the new function in the right order. If not, ignore it.
513 // Defer PHI resolution until rest of function is resolved.
514 SmallVector<const PHINode*, 16> PHIToResolve;
515 for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
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 if (const PHINode *PN = dyn_cast<PHINode>(I))
528 PHIToResolve.push_back(PN);
532 // Finally, remap the terminator instructions, as those can't be remapped
533 // until all BBs are mapped.
534 RemapInstruction(NewBB->getTerminator(), VMap,
535 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
536 TypeMapper, Materializer);
539 // Defer PHI resolution until rest of function is resolved, PHI resolution
540 // requires the CFG to be up-to-date.
541 for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
542 const PHINode *OPN = PHIToResolve[phino];
543 unsigned NumPreds = OPN->getNumIncomingValues();
544 const BasicBlock *OldBB = OPN->getParent();
545 BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]);
547 // Map operands for blocks that are live and remove operands for blocks
549 for (; phino != PHIToResolve.size() &&
550 PHIToResolve[phino]->getParent() == OldBB; ++phino) {
551 OPN = PHIToResolve[phino];
552 PHINode *PN = cast<PHINode>(VMap[OPN]);
553 for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
554 Value *V = VMap[PN->getIncomingBlock(pred)];
555 if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) {
556 Value *InVal = MapValue(PN->getIncomingValue(pred),
558 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
559 assert(InVal && "Unknown input value?");
560 PN->setIncomingValue(pred, InVal);
561 PN->setIncomingBlock(pred, MappedBlock);
563 PN->removeIncomingValue(pred, false);
564 --pred, --e; // Revisit the next entry.
569 // The loop above has removed PHI entries for those blocks that are dead
570 // and has updated others. However, if a block is live (i.e. copied over)
571 // but its terminator has been changed to not go to this block, then our
572 // phi nodes will have invalid entries. Update the PHI nodes in this
574 PHINode *PN = cast<PHINode>(NewBB->begin());
575 NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB));
576 if (NumPreds != PN->getNumIncomingValues()) {
577 assert(NumPreds < PN->getNumIncomingValues());
578 // Count how many times each predecessor comes to this block.
579 std::map<BasicBlock*, unsigned> PredCount;
580 for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
584 // Figure out how many entries to remove from each PHI.
585 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
586 ++PredCount[PN->getIncomingBlock(i)];
588 // At this point, the excess predecessor entries are positive in the
589 // map. Loop over all of the PHIs and remove excess predecessor
591 BasicBlock::iterator I = NewBB->begin();
592 for (; (PN = dyn_cast<PHINode>(I)); ++I) {
593 for (std::map<BasicBlock*, unsigned>::iterator PCI =PredCount.begin(),
594 E = PredCount.end(); PCI != E; ++PCI) {
595 BasicBlock *Pred = PCI->first;
596 for (unsigned NumToRemove = PCI->second; NumToRemove; --NumToRemove)
597 PN->removeIncomingValue(Pred, false);
602 // If the loops above have made these phi nodes have 0 or 1 operand,
603 // replace them with undef or the input value. We must do this for
604 // correctness, because 0-operand phis are not valid.
605 PN = cast<PHINode>(NewBB->begin());
606 if (PN->getNumIncomingValues() == 0) {
607 BasicBlock::iterator I = NewBB->begin();
608 BasicBlock::const_iterator OldI = OldBB->begin();
609 while ((PN = dyn_cast<PHINode>(I++))) {
610 Value *NV = UndefValue::get(PN->getType());
611 PN->replaceAllUsesWith(NV);
612 assert(VMap[OldI] == PN && "VMap mismatch");
614 PN->eraseFromParent();
620 // Make a second pass over the PHINodes now that all of them have been
621 // remapped into the new function, simplifying the PHINode and performing any
622 // recursive simplifications exposed. This will transparently update the
623 // WeakVH in the VMap. Notably, we rely on that so that if we coalesce
624 // two PHINodes, the iteration over the old PHIs remains valid, and the
625 // mapping will just map us to the new node (which may not even be a PHI
627 for (unsigned Idx = 0, Size = PHIToResolve.size(); Idx != Size; ++Idx)
628 if (PHINode *PN = dyn_cast<PHINode>(VMap[PHIToResolve[Idx]]))
629 recursivelySimplifyInstruction(PN, DL);
631 // Now that the inlined function body has been fully constructed, go through
632 // and zap unconditional fall-through branches. This happen all the time when
633 // specializing code: code specialization turns conditional branches into
634 // uncond branches, and this code folds them.
635 Function::iterator Begin = cast<BasicBlock>(VMap[StartingBB]);
636 Function::iterator I = Begin;
637 while (I != NewFunc->end()) {
638 // Check if this block has become dead during inlining or other
639 // simplifications. Note that the first block will appear dead, as it has
640 // not yet been wired up properly.
641 if (I != Begin && (pred_begin(I) == pred_end(I) ||
642 I->getSinglePredecessor() == I)) {
643 BasicBlock *DeadBB = I++;
644 DeleteDeadBlock(DeadBB);
648 // We need to simplify conditional branches and switches with a constant
649 // operand. We try to prune these out when cloning, but if the
650 // simplification required looking through PHI nodes, those are only
651 // available after forming the full basic block. That may leave some here,
652 // and we still want to prune the dead code as early as possible.
653 ConstantFoldTerminator(I);
655 BranchInst *BI = dyn_cast<BranchInst>(I->getTerminator());
656 if (!BI || BI->isConditional()) { ++I; continue; }
658 BasicBlock *Dest = BI->getSuccessor(0);
659 if (!Dest->getSinglePredecessor()) {
663 // We shouldn't be able to get single-entry PHI nodes here, as instsimplify
664 // above should have zapped all of them..
665 assert(!isa<PHINode>(Dest->begin()));
667 // We know all single-entry PHI nodes in the inlined function have been
668 // removed, so we just need to splice the blocks.
669 BI->eraseFromParent();
671 // Make all PHI nodes that referred to Dest now refer to I as their source.
672 Dest->replaceAllUsesWith(I);
674 // Move all the instructions in the succ to the pred.
675 I->getInstList().splice(I->end(), Dest->getInstList());
677 // Remove the dest block.
678 Dest->eraseFromParent();
680 // Do not increment I, iteratively merge all things this block branches to.
683 // Make a final pass over the basic blocks from theh old function to gather
684 // any return instructions which survived folding. We have to do this here
685 // because we can iteratively remove and merge returns above.
686 for (Function::iterator I = cast<BasicBlock>(VMap[StartingBB]),
689 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator()))
690 Returns.push_back(RI);
694 /// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto,
695 /// except that it does some simple constant prop and DCE on the fly. The
696 /// effect of this is to copy significantly less code in cases where (for
697 /// example) a function call with constant arguments is inlined, and those
698 /// constant arguments cause a significant amount of code in the callee to be
699 /// dead. Since this doesn't produce an exact copy of the input, it can't be
700 /// used for things like CloneFunction or CloneModule.
701 void llvm::CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
702 ValueToValueMapTy &VMap,
703 bool ModuleLevelChanges,
704 SmallVectorImpl<ReturnInst*> &Returns,
705 const char *NameSuffix,
706 ClonedCodeInfo *CodeInfo,
707 const DataLayout *DL,
708 Instruction *TheCall) {
709 CloneAndPruneIntoFromInst(NewFunc, OldFunc, OldFunc->front().begin(),
710 VMap, ModuleLevelChanges, Returns, NameSuffix,
711 CodeInfo, DL, nullptr);