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 AttributeSet OldAttrs = OldFunc->getAttributes();
93 // Clone any argument attributes that are present in the VMap.
94 for (Function::const_arg_iterator I = OldFunc->arg_begin(),
95 E = OldFunc->arg_end();
97 if (Argument *Anew = dyn_cast<Argument>(VMap[I])) {
99 OldAttrs.getParamAttributes(I->getArgNo() + 1);
100 if (attrs.getNumSlots() > 0)
101 Anew->addAttr(attrs);
104 NewFunc->setAttributes(NewFunc->getAttributes()
105 .addAttributes(NewFunc->getContext(),
106 AttributeSet::ReturnIndex,
107 OldAttrs.getRetAttributes()));
108 NewFunc->setAttributes(NewFunc->getAttributes()
109 .addAttributes(NewFunc->getContext(),
110 AttributeSet::FunctionIndex,
111 OldAttrs.getFnAttributes()));
113 // Loop over all of the basic blocks in the function, cloning them as
114 // appropriate. Note that we save BE this way in order to handle cloning of
115 // recursive functions into themselves.
117 for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
119 const BasicBlock &BB = *BI;
121 // Create a new basic block and copy instructions into it!
122 BasicBlock *CBB = CloneBasicBlock(&BB, VMap, NameSuffix, NewFunc, CodeInfo);
124 // Add basic block mapping.
127 // It is only legal to clone a function if a block address within that
128 // function is never referenced outside of the function. Given that, we
129 // want to map block addresses from the old function to block addresses in
130 // the clone. (This is different from the generic ValueMapper
131 // implementation, which generates an invalid blockaddress when
132 // cloning a function.)
133 if (BB.hasAddressTaken()) {
134 Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
135 const_cast<BasicBlock*>(&BB));
136 VMap[OldBBAddr] = BlockAddress::get(NewFunc, CBB);
139 // Note return instructions for the caller.
140 if (ReturnInst *RI = dyn_cast<ReturnInst>(CBB->getTerminator()))
141 Returns.push_back(RI);
144 // Loop over all of the instructions in the function, fixing up operand
145 // references as we go. This uses VMap to do all the hard work.
146 for (Function::iterator BB = cast<BasicBlock>(VMap[OldFunc->begin()]),
147 BE = NewFunc->end(); BB != BE; ++BB)
148 // Loop over all instructions, fixing each one as we find it...
149 for (BasicBlock::iterator II = BB->begin(); II != BB->end(); ++II)
150 RemapInstruction(II, VMap,
151 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
152 TypeMapper, Materializer);
155 // Find the MDNode which corresponds to the DISubprogram data that described F.
156 static MDNode* FindSubprogram(const Function *F, DebugInfoFinder &Finder) {
157 for (DISubprogram Subprogram : Finder.subprograms()) {
158 if (Subprogram.describes(F)) return Subprogram;
163 // Add an operand to an existing MDNode. The new operand will be added at the
164 // back of the operand list.
165 static void AddOperand(MDNode *Node, Value *Operand) {
166 SmallVector<Value*, 16> Operands;
167 for (unsigned i = 0; i < Node->getNumOperands(); i++) {
168 Operands.push_back(Node->getOperand(i));
170 Operands.push_back(Operand);
171 MDNode *NewNode = MDNode::get(Node->getContext(), Operands);
172 Node->replaceAllUsesWith(NewNode);
175 // Clone the module-level debug info associated with OldFunc. The cloned data
176 // will point to NewFunc instead.
177 static void CloneDebugInfoMetadata(Function *NewFunc, const Function *OldFunc,
178 ValueToValueMapTy &VMap) {
179 DebugInfoFinder Finder;
180 Finder.processModule(*OldFunc->getParent());
182 const MDNode *OldSubprogramMDNode = FindSubprogram(OldFunc, Finder);
183 if (!OldSubprogramMDNode) return;
185 // Ensure that OldFunc appears in the map.
186 // (if it's already there it must point to NewFunc anyway)
187 VMap[OldFunc] = NewFunc;
188 DISubprogram NewSubprogram(MapValue(OldSubprogramMDNode, VMap));
190 for (DICompileUnit CU : Finder.compile_units()) {
191 DIArray Subprograms(CU.getSubprograms());
193 // If the compile unit's function list contains the old function, it should
194 // also contain the new one.
195 for (unsigned i = 0; i < Subprograms.getNumElements(); i++) {
196 if ((MDNode*)Subprograms.getElement(i) == OldSubprogramMDNode) {
197 AddOperand(Subprograms, NewSubprogram);
203 /// CloneFunction - Return a copy of the specified function, but without
204 /// embedding the function into another module. Also, any references specified
205 /// in the VMap are changed to refer to their mapped value instead of the
206 /// original one. If any of the arguments to the function are in the VMap,
207 /// the arguments are deleted from the resultant function. The VMap is
208 /// updated to include mappings from all of the instructions and basicblocks in
209 /// the function from their old to new values.
211 Function *llvm::CloneFunction(const Function *F, ValueToValueMapTy &VMap,
212 bool ModuleLevelChanges,
213 ClonedCodeInfo *CodeInfo) {
214 std::vector<Type*> ArgTypes;
216 // The user might be deleting arguments to the function by specifying them in
217 // the VMap. If so, we need to not add the arguments to the arg ty vector
219 for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
221 if (VMap.count(I) == 0) // Haven't mapped the argument to anything yet?
222 ArgTypes.push_back(I->getType());
224 // Create a new function type...
225 FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(),
226 ArgTypes, F->getFunctionType()->isVarArg());
228 // Create the new function...
229 Function *NewF = Function::Create(FTy, F->getLinkage(), F->getName());
231 // Loop over the arguments, copying the names of the mapped arguments over...
232 Function::arg_iterator DestI = NewF->arg_begin();
233 for (Function::const_arg_iterator I = F->arg_begin(), E = F->arg_end();
235 if (VMap.count(I) == 0) { // Is this argument preserved?
236 DestI->setName(I->getName()); // Copy the name over...
237 VMap[I] = DestI++; // Add mapping to VMap
240 if (ModuleLevelChanges)
241 CloneDebugInfoMetadata(NewF, F, VMap);
243 SmallVector<ReturnInst*, 8> Returns; // Ignore returns cloned.
244 CloneFunctionInto(NewF, F, VMap, ModuleLevelChanges, Returns, "", CodeInfo);
251 /// PruningFunctionCloner - This class is a private class used to implement
252 /// the CloneAndPruneFunctionInto method.
253 struct PruningFunctionCloner {
255 const Function *OldFunc;
256 ValueToValueMapTy &VMap;
257 bool ModuleLevelChanges;
258 const char *NameSuffix;
259 ClonedCodeInfo *CodeInfo;
260 const DataLayout *DL;
262 PruningFunctionCloner(Function *newFunc, const Function *oldFunc,
263 ValueToValueMapTy &valueMap,
264 bool moduleLevelChanges,
265 const char *nameSuffix,
266 ClonedCodeInfo *codeInfo,
267 const DataLayout *DL)
268 : NewFunc(newFunc), OldFunc(oldFunc),
269 VMap(valueMap), ModuleLevelChanges(moduleLevelChanges),
270 NameSuffix(nameSuffix), CodeInfo(codeInfo), DL(DL) {
273 /// CloneBlock - The specified block is found to be reachable, clone it and
274 /// anything that it can reach.
275 void CloneBlock(const BasicBlock *BB,
276 std::vector<const BasicBlock*> &ToClone);
280 /// CloneBlock - The specified block is found to be reachable, clone it and
281 /// anything that it can reach.
282 void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
283 std::vector<const BasicBlock*> &ToClone){
284 WeakVH &BBEntry = VMap[BB];
286 // Have we already cloned this block?
289 // Nope, clone it now.
291 BBEntry = NewBB = BasicBlock::Create(BB->getContext());
292 if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
294 // It is only legal to clone a function if a block address within that
295 // function is never referenced outside of the function. Given that, we
296 // want to map block addresses from the old function to block addresses in
297 // the clone. (This is different from the generic ValueMapper
298 // implementation, which generates an invalid blockaddress when
299 // cloning a function.)
301 // Note that we don't need to fix the mapping for unreachable blocks;
302 // the default mapping there is safe.
303 if (BB->hasAddressTaken()) {
304 Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
305 const_cast<BasicBlock*>(BB));
306 VMap[OldBBAddr] = BlockAddress::get(NewFunc, NewBB);
310 bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
312 // Loop over all instructions, and copy them over, DCE'ing as we go. This
313 // loop doesn't include the terminator.
314 for (BasicBlock::const_iterator II = BB->begin(), IE = --BB->end();
316 Instruction *NewInst = II->clone();
318 // Eagerly remap operands to the newly cloned instruction, except for PHI
319 // nodes for which we defer processing until we update the CFG.
320 if (!isa<PHINode>(NewInst)) {
321 RemapInstruction(NewInst, VMap,
322 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
324 // If we can simplify this instruction to some other value, simply add
325 // a mapping to that value rather than inserting a new instruction into
327 if (Value *V = SimplifyInstruction(NewInst, DL)) {
328 // On the off-chance that this simplifies to an instruction in the old
329 // function, map it back into the new function.
330 if (Value *MappedV = VMap.lookup(V))
340 NewInst->setName(II->getName()+NameSuffix);
341 VMap[II] = NewInst; // Add instruction map to value.
342 NewBB->getInstList().push_back(NewInst);
343 hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
344 if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
345 if (isa<ConstantInt>(AI->getArraySize()))
346 hasStaticAllocas = true;
348 hasDynamicAllocas = true;
352 // Finally, clone over the terminator.
353 const TerminatorInst *OldTI = BB->getTerminator();
354 bool TerminatorDone = false;
355 if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) {
356 if (BI->isConditional()) {
357 // If the condition was a known constant in the callee...
358 ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
359 // Or is a known constant in the caller...
361 Value *V = VMap[BI->getCondition()];
362 Cond = dyn_cast_or_null<ConstantInt>(V);
365 // Constant fold to uncond branch!
367 BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue());
368 VMap[OldTI] = BranchInst::Create(Dest, NewBB);
369 ToClone.push_back(Dest);
370 TerminatorDone = true;
373 } else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) {
374 // If switching on a value known constant in the caller.
375 ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition());
376 if (Cond == 0) { // Or known constant after constant prop in the callee...
377 Value *V = VMap[SI->getCondition()];
378 Cond = dyn_cast_or_null<ConstantInt>(V);
380 if (Cond) { // Constant fold to uncond branch!
381 SwitchInst::ConstCaseIt Case = SI->findCaseValue(Cond);
382 BasicBlock *Dest = const_cast<BasicBlock*>(Case.getCaseSuccessor());
383 VMap[OldTI] = BranchInst::Create(Dest, NewBB);
384 ToClone.push_back(Dest);
385 TerminatorDone = true;
389 if (!TerminatorDone) {
390 Instruction *NewInst = OldTI->clone();
391 if (OldTI->hasName())
392 NewInst->setName(OldTI->getName()+NameSuffix);
393 NewBB->getInstList().push_back(NewInst);
394 VMap[OldTI] = NewInst; // Add instruction map to value.
396 // Recursively clone any reachable successor blocks.
397 const TerminatorInst *TI = BB->getTerminator();
398 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
399 ToClone.push_back(TI->getSuccessor(i));
403 CodeInfo->ContainsCalls |= hasCalls;
404 CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
405 CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
406 BB != &BB->getParent()->front();
410 /// CloneAndPruneFunctionInto - This works exactly like CloneFunctionInto,
411 /// except that it does some simple constant prop and DCE on the fly. The
412 /// effect of this is to copy significantly less code in cases where (for
413 /// example) a function call with constant arguments is inlined, and those
414 /// constant arguments cause a significant amount of code in the callee to be
415 /// dead. Since this doesn't produce an exact copy of the input, it can't be
416 /// used for things like CloneFunction or CloneModule.
417 void llvm::CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
418 ValueToValueMapTy &VMap,
419 bool ModuleLevelChanges,
420 SmallVectorImpl<ReturnInst*> &Returns,
421 const char *NameSuffix,
422 ClonedCodeInfo *CodeInfo,
423 const DataLayout *DL,
424 Instruction *TheCall) {
425 assert(NameSuffix && "NameSuffix cannot be null!");
428 for (Function::const_arg_iterator II = OldFunc->arg_begin(),
429 E = OldFunc->arg_end(); II != E; ++II)
430 assert(VMap.count(II) && "No mapping from source argument specified!");
433 PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges,
434 NameSuffix, CodeInfo, DL);
436 // Clone the entry block, and anything recursively reachable from it.
437 std::vector<const BasicBlock*> CloneWorklist;
438 CloneWorklist.push_back(&OldFunc->getEntryBlock());
439 while (!CloneWorklist.empty()) {
440 const BasicBlock *BB = CloneWorklist.back();
441 CloneWorklist.pop_back();
442 PFC.CloneBlock(BB, CloneWorklist);
445 // Loop over all of the basic blocks in the old function. If the block was
446 // reachable, we have cloned it and the old block is now in the value map:
447 // insert it into the new function in the right order. If not, ignore it.
449 // Defer PHI resolution until rest of function is resolved.
450 SmallVector<const PHINode*, 16> PHIToResolve;
451 for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
454 BasicBlock *NewBB = cast_or_null<BasicBlock>(V);
455 if (NewBB == 0) continue; // Dead block.
457 // Add the new block to the new function.
458 NewFunc->getBasicBlockList().push_back(NewBB);
460 // Handle PHI nodes specially, as we have to remove references to dead
462 for (BasicBlock::const_iterator I = BI->begin(), E = BI->end(); I != E; ++I)
463 if (const PHINode *PN = dyn_cast<PHINode>(I))
464 PHIToResolve.push_back(PN);
468 // Finally, remap the terminator instructions, as those can't be remapped
469 // until all BBs are mapped.
470 RemapInstruction(NewBB->getTerminator(), VMap,
471 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
474 // Defer PHI resolution until rest of function is resolved, PHI resolution
475 // requires the CFG to be up-to-date.
476 for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
477 const PHINode *OPN = PHIToResolve[phino];
478 unsigned NumPreds = OPN->getNumIncomingValues();
479 const BasicBlock *OldBB = OPN->getParent();
480 BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]);
482 // Map operands for blocks that are live and remove operands for blocks
484 for (; phino != PHIToResolve.size() &&
485 PHIToResolve[phino]->getParent() == OldBB; ++phino) {
486 OPN = PHIToResolve[phino];
487 PHINode *PN = cast<PHINode>(VMap[OPN]);
488 for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
489 Value *V = VMap[PN->getIncomingBlock(pred)];
490 if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) {
491 Value *InVal = MapValue(PN->getIncomingValue(pred),
493 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
494 assert(InVal && "Unknown input value?");
495 PN->setIncomingValue(pred, InVal);
496 PN->setIncomingBlock(pred, MappedBlock);
498 PN->removeIncomingValue(pred, false);
499 --pred, --e; // Revisit the next entry.
504 // The loop above has removed PHI entries for those blocks that are dead
505 // and has updated others. However, if a block is live (i.e. copied over)
506 // but its terminator has been changed to not go to this block, then our
507 // phi nodes will have invalid entries. Update the PHI nodes in this
509 PHINode *PN = cast<PHINode>(NewBB->begin());
510 NumPreds = std::distance(pred_begin(NewBB), pred_end(NewBB));
511 if (NumPreds != PN->getNumIncomingValues()) {
512 assert(NumPreds < PN->getNumIncomingValues());
513 // Count how many times each predecessor comes to this block.
514 std::map<BasicBlock*, unsigned> PredCount;
515 for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
519 // Figure out how many entries to remove from each PHI.
520 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
521 ++PredCount[PN->getIncomingBlock(i)];
523 // At this point, the excess predecessor entries are positive in the
524 // map. Loop over all of the PHIs and remove excess predecessor
526 BasicBlock::iterator I = NewBB->begin();
527 for (; (PN = dyn_cast<PHINode>(I)); ++I) {
528 for (std::map<BasicBlock*, unsigned>::iterator PCI =PredCount.begin(),
529 E = PredCount.end(); PCI != E; ++PCI) {
530 BasicBlock *Pred = PCI->first;
531 for (unsigned NumToRemove = PCI->second; NumToRemove; --NumToRemove)
532 PN->removeIncomingValue(Pred, false);
537 // If the loops above have made these phi nodes have 0 or 1 operand,
538 // replace them with undef or the input value. We must do this for
539 // correctness, because 0-operand phis are not valid.
540 PN = cast<PHINode>(NewBB->begin());
541 if (PN->getNumIncomingValues() == 0) {
542 BasicBlock::iterator I = NewBB->begin();
543 BasicBlock::const_iterator OldI = OldBB->begin();
544 while ((PN = dyn_cast<PHINode>(I++))) {
545 Value *NV = UndefValue::get(PN->getType());
546 PN->replaceAllUsesWith(NV);
547 assert(VMap[OldI] == PN && "VMap mismatch");
549 PN->eraseFromParent();
555 // Make a second pass over the PHINodes now that all of them have been
556 // remapped into the new function, simplifying the PHINode and performing any
557 // recursive simplifications exposed. This will transparently update the
558 // WeakVH in the VMap. Notably, we rely on that so that if we coalesce
559 // two PHINodes, the iteration over the old PHIs remains valid, and the
560 // mapping will just map us to the new node (which may not even be a PHI
562 for (unsigned Idx = 0, Size = PHIToResolve.size(); Idx != Size; ++Idx)
563 if (PHINode *PN = dyn_cast<PHINode>(VMap[PHIToResolve[Idx]]))
564 recursivelySimplifyInstruction(PN, DL);
566 // Now that the inlined function body has been fully constructed, go through
567 // and zap unconditional fall-through branches. This happen all the time when
568 // specializing code: code specialization turns conditional branches into
569 // uncond branches, and this code folds them.
570 Function::iterator Begin = cast<BasicBlock>(VMap[&OldFunc->getEntryBlock()]);
571 Function::iterator I = Begin;
572 while (I != NewFunc->end()) {
573 // Check if this block has become dead during inlining or other
574 // simplifications. Note that the first block will appear dead, as it has
575 // not yet been wired up properly.
576 if (I != Begin && (pred_begin(I) == pred_end(I) ||
577 I->getSinglePredecessor() == I)) {
578 BasicBlock *DeadBB = I++;
579 DeleteDeadBlock(DeadBB);
583 // We need to simplify conditional branches and switches with a constant
584 // operand. We try to prune these out when cloning, but if the
585 // simplification required looking through PHI nodes, those are only
586 // available after forming the full basic block. That may leave some here,
587 // and we still want to prune the dead code as early as possible.
588 ConstantFoldTerminator(I);
590 BranchInst *BI = dyn_cast<BranchInst>(I->getTerminator());
591 if (!BI || BI->isConditional()) { ++I; continue; }
593 BasicBlock *Dest = BI->getSuccessor(0);
594 if (!Dest->getSinglePredecessor()) {
598 // We shouldn't be able to get single-entry PHI nodes here, as instsimplify
599 // above should have zapped all of them..
600 assert(!isa<PHINode>(Dest->begin()));
602 // We know all single-entry PHI nodes in the inlined function have been
603 // removed, so we just need to splice the blocks.
604 BI->eraseFromParent();
606 // Make all PHI nodes that referred to Dest now refer to I as their source.
607 Dest->replaceAllUsesWith(I);
609 // Move all the instructions in the succ to the pred.
610 I->getInstList().splice(I->end(), Dest->getInstList());
612 // Remove the dest block.
613 Dest->eraseFromParent();
615 // Do not increment I, iteratively merge all things this block branches to.
618 // Make a final pass over the basic blocks from theh old function to gather
619 // any return instructions which survived folding. We have to do this here
620 // because we can iteratively remove and merge returns above.
621 for (Function::iterator I = cast<BasicBlock>(VMap[&OldFunc->getEntryBlock()]),
624 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator()))
625 Returns.push_back(RI);