1 //===- CloneFunction.cpp - Clone a function into another function ---------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file implements the CloneFunctionInto interface, which is used as the
10 // low-level function cloner. This is used by the CloneFunction and function
11 // inliner to do the dirty work of copying the body of a function around.
12 //
13 //===----------------------------------------------------------------------===//
14
15 #include "llvm/ADT/SetVector.h"
16 #include "llvm/ADT/SmallVector.h"
17 #include "llvm/Analysis/ConstantFolding.h"
18 #include "llvm/Analysis/DomTreeUpdater.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/Cloning.h"
34 #include "llvm/Transforms/Utils/Local.h"
35 #include "llvm/Transforms/Utils/ValueMapper.h"
36 #include <map>
37 using namespace llvm;
38
39 /// See comments in Cloning.h.
CloneBasicBlock(const BasicBlock * BB,ValueToValueMapTy & VMap,const Twine & NameSuffix,Function * F,ClonedCodeInfo * CodeInfo,DebugInfoFinder * DIFinder)40 BasicBlock *llvm::CloneBasicBlock(const BasicBlock *BB, ValueToValueMapTy &VMap,
41 const Twine &NameSuffix, Function *F,
42 ClonedCodeInfo *CodeInfo,
43 DebugInfoFinder *DIFinder) {
44 DenseMap<const MDNode *, MDNode *> Cache;
45 BasicBlock *NewBB = BasicBlock::Create(BB->getContext(), "", F);
46 if (BB->hasName())
47 NewBB->setName(BB->getName() + NameSuffix);
48
49 bool hasCalls = false, hasDynamicAllocas = false;
50 Module *TheModule = F ? F->getParent() : nullptr;
51
52 // Loop over all instructions, and copy them over.
53 for (const Instruction &I : *BB) {
54 if (DIFinder && TheModule)
55 DIFinder->processInstruction(*TheModule, I);
56
57 Instruction *NewInst = I.clone();
58 if (I.hasName())
59 NewInst->setName(I.getName() + NameSuffix);
60 NewBB->getInstList().push_back(NewInst);
61 VMap[&I] = NewInst; // Add instruction map to value.
62
63 hasCalls |= (isa<CallInst>(I) && !isa<DbgInfoIntrinsic>(I));
64 if (const AllocaInst *AI = dyn_cast<AllocaInst>(&I)) {
65 if (!AI->isStaticAlloca()) {
66 hasDynamicAllocas = true;
67 }
68 }
69 }
70
71 if (CodeInfo) {
72 CodeInfo->ContainsCalls |= hasCalls;
73 CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
74 }
75 return NewBB;
76 }
77
78 // Clone OldFunc into NewFunc, transforming the old arguments into references to
79 // VMap values.
80 //
CloneFunctionInto(Function * NewFunc,const Function * OldFunc,ValueToValueMapTy & VMap,bool ModuleLevelChanges,SmallVectorImpl<ReturnInst * > & Returns,const char * NameSuffix,ClonedCodeInfo * CodeInfo,ValueMapTypeRemapper * TypeMapper,ValueMaterializer * Materializer)81 void llvm::CloneFunctionInto(Function *NewFunc, const Function *OldFunc,
82 ValueToValueMapTy &VMap,
83 bool ModuleLevelChanges,
84 SmallVectorImpl<ReturnInst*> &Returns,
85 const char *NameSuffix, ClonedCodeInfo *CodeInfo,
86 ValueMapTypeRemapper *TypeMapper,
87 ValueMaterializer *Materializer) {
88 assert(NameSuffix && "NameSuffix cannot be null!");
89
90 #ifndef NDEBUG
91 for (const Argument &I : OldFunc->args())
92 assert(VMap.count(&I) && "No mapping from source argument specified!");
93 #endif
94
95 // Copy all attributes other than those stored in the AttributeList. We need
96 // to remap the parameter indices of the AttributeList.
97 AttributeList NewAttrs = NewFunc->getAttributes();
98 NewFunc->copyAttributesFrom(OldFunc);
99 NewFunc->setAttributes(NewAttrs);
100
101 // Fix up the personality function that got copied over.
102 if (OldFunc->hasPersonalityFn())
103 NewFunc->setPersonalityFn(
104 MapValue(OldFunc->getPersonalityFn(), VMap,
105 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
106 TypeMapper, Materializer));
107
108 SmallVector<AttributeSet, 4> NewArgAttrs(NewFunc->arg_size());
109 AttributeList OldAttrs = OldFunc->getAttributes();
110
111 // Clone any argument attributes that are present in the VMap.
112 for (const Argument &OldArg : OldFunc->args()) {
113 if (Argument *NewArg = dyn_cast<Argument>(VMap[&OldArg])) {
114 NewArgAttrs[NewArg->getArgNo()] =
115 OldAttrs.getParamAttributes(OldArg.getArgNo());
116 }
117 }
118
119 NewFunc->setAttributes(
120 AttributeList::get(NewFunc->getContext(), OldAttrs.getFnAttributes(),
121 OldAttrs.getRetAttributes(), NewArgAttrs));
122
123 bool MustCloneSP =
124 OldFunc->getParent() && OldFunc->getParent() == NewFunc->getParent();
125 DISubprogram *SP = OldFunc->getSubprogram();
126 if (SP) {
127 assert(!MustCloneSP || ModuleLevelChanges);
128 // Add mappings for some DebugInfo nodes that we don't want duplicated
129 // even if they're distinct.
130 auto &MD = VMap.MD();
131 MD[SP->getUnit()].reset(SP->getUnit());
132 MD[SP->getType()].reset(SP->getType());
133 MD[SP->getFile()].reset(SP->getFile());
134 // If we're not cloning into the same module, no need to clone the
135 // subprogram
136 if (!MustCloneSP)
137 MD[SP].reset(SP);
138 }
139
140 // Everything else beyond this point deals with function instructions,
141 // so if we are dealing with a function declaration, we're done.
142 if (OldFunc->isDeclaration())
143 return;
144
145 // When we remap instructions, we want to avoid duplicating inlined
146 // DISubprograms, so record all subprograms we find as we duplicate
147 // instructions and then freeze them in the MD map.
148 // We also record information about dbg.value and dbg.declare to avoid
149 // duplicating the types.
150 DebugInfoFinder DIFinder;
151
152 // Loop over all of the basic blocks in the function, cloning them as
153 // appropriate. Note that we save BE this way in order to handle cloning of
154 // recursive functions into themselves.
155 for (Function::const_iterator BI = OldFunc->begin(), BE = OldFunc->end();
156 BI != BE; ++BI) {
157 const BasicBlock &BB = *BI;
158
159 // Create a new basic block and copy instructions into it!
160 BasicBlock *CBB = CloneBasicBlock(&BB, VMap, NameSuffix, NewFunc, CodeInfo,
161 ModuleLevelChanges ? &DIFinder : nullptr);
162
163 // Add basic block mapping.
164 VMap[&BB] = CBB;
165
166 // It is only legal to clone a function if a block address within that
167 // function is never referenced outside of the function. Given that, we
168 // want to map block addresses from the old function to block addresses in
169 // the clone. (This is different from the generic ValueMapper
170 // implementation, which generates an invalid blockaddress when
171 // cloning a function.)
172 if (BB.hasAddressTaken()) {
173 Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
174 const_cast<BasicBlock*>(&BB));
175 VMap[OldBBAddr] = BlockAddress::get(NewFunc, CBB);
176 }
177
178 // Note return instructions for the caller.
179 if (ReturnInst *RI = dyn_cast<ReturnInst>(CBB->getTerminator()))
180 Returns.push_back(RI);
181 }
182
183 for (DISubprogram *ISP : DIFinder.subprograms())
184 if (ISP != SP)
185 VMap.MD()[ISP].reset(ISP);
186
187 for (DICompileUnit *CU : DIFinder.compile_units())
188 VMap.MD()[CU].reset(CU);
189
190 for (DIType *Type : DIFinder.types())
191 VMap.MD()[Type].reset(Type);
192
193 // Duplicate the metadata that is attached to the cloned function.
194 // Subprograms/CUs/types that were already mapped to themselves won't be
195 // duplicated.
196 SmallVector<std::pair<unsigned, MDNode *>, 1> MDs;
197 OldFunc->getAllMetadata(MDs);
198 for (auto MD : MDs) {
199 NewFunc->addMetadata(
200 MD.first,
201 *MapMetadata(MD.second, VMap,
202 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
203 TypeMapper, Materializer));
204 }
205
206 // Loop over all of the instructions in the function, fixing up operand
207 // references as we go. This uses VMap to do all the hard work.
208 for (Function::iterator BB =
209 cast<BasicBlock>(VMap[&OldFunc->front()])->getIterator(),
210 BE = NewFunc->end();
211 BB != BE; ++BB)
212 // Loop over all instructions, fixing each one as we find it...
213 for (Instruction &II : *BB)
214 RemapInstruction(&II, VMap,
215 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
216 TypeMapper, Materializer);
217
218 // Register all DICompileUnits of the old parent module in the new parent module
219 auto* OldModule = OldFunc->getParent();
220 auto* NewModule = NewFunc->getParent();
221 if (OldModule && NewModule && OldModule != NewModule && DIFinder.compile_unit_count()) {
222 auto* NMD = NewModule->getOrInsertNamedMetadata("llvm.dbg.cu");
223 // Avoid multiple insertions of the same DICompileUnit to NMD.
224 SmallPtrSet<const void*, 8> Visited;
225 for (auto* Operand : NMD->operands())
226 Visited.insert(Operand);
227 for (auto* Unit : DIFinder.compile_units())
228 // VMap.MD()[Unit] == Unit
229 if (Visited.insert(Unit).second)
230 NMD->addOperand(Unit);
231 }
232 }
233
234 /// Return a copy of the specified function and add it to that function's
235 /// module. Also, any references specified in the VMap are changed to refer to
236 /// their mapped value instead of the original one. If any of the arguments to
237 /// the function are in the VMap, the arguments are deleted from the resultant
238 /// function. The VMap is updated to include mappings from all of the
239 /// instructions and basicblocks in the function from their old to new values.
240 ///
CloneFunction(Function * F,ValueToValueMapTy & VMap,ClonedCodeInfo * CodeInfo)241 Function *llvm::CloneFunction(Function *F, ValueToValueMapTy &VMap,
242 ClonedCodeInfo *CodeInfo) {
243 std::vector<Type*> ArgTypes;
244
245 // The user might be deleting arguments to the function by specifying them in
246 // the VMap. If so, we need to not add the arguments to the arg ty vector
247 //
248 for (const Argument &I : F->args())
249 if (VMap.count(&I) == 0) // Haven't mapped the argument to anything yet?
250 ArgTypes.push_back(I.getType());
251
252 // Create a new function type...
253 FunctionType *FTy = FunctionType::get(F->getFunctionType()->getReturnType(),
254 ArgTypes, F->getFunctionType()->isVarArg());
255
256 // Create the new function...
257 Function *NewF = Function::Create(FTy, F->getLinkage(), F->getAddressSpace(),
258 F->getName(), F->getParent());
259
260 // Loop over the arguments, copying the names of the mapped arguments over...
261 Function::arg_iterator DestI = NewF->arg_begin();
262 for (const Argument & I : F->args())
263 if (VMap.count(&I) == 0) { // Is this argument preserved?
264 DestI->setName(I.getName()); // Copy the name over...
265 VMap[&I] = &*DestI++; // Add mapping to VMap
266 }
267
268 SmallVector<ReturnInst*, 8> Returns; // Ignore returns cloned.
269 CloneFunctionInto(NewF, F, VMap, F->getSubprogram() != nullptr, Returns, "",
270 CodeInfo);
271
272 return NewF;
273 }
274
275
276
277 namespace {
278 /// This is a private class used to implement CloneAndPruneFunctionInto.
279 struct PruningFunctionCloner {
280 Function *NewFunc;
281 const Function *OldFunc;
282 ValueToValueMapTy &VMap;
283 bool ModuleLevelChanges;
284 const char *NameSuffix;
285 ClonedCodeInfo *CodeInfo;
286
287 public:
PruningFunctionCloner__anon310110550111::PruningFunctionCloner288 PruningFunctionCloner(Function *newFunc, const Function *oldFunc,
289 ValueToValueMapTy &valueMap, bool moduleLevelChanges,
290 const char *nameSuffix, ClonedCodeInfo *codeInfo)
291 : NewFunc(newFunc), OldFunc(oldFunc), VMap(valueMap),
292 ModuleLevelChanges(moduleLevelChanges), NameSuffix(nameSuffix),
293 CodeInfo(codeInfo) {}
294
295 /// The specified block is found to be reachable, clone it and
296 /// anything that it can reach.
297 void CloneBlock(const BasicBlock *BB,
298 BasicBlock::const_iterator StartingInst,
299 std::vector<const BasicBlock*> &ToClone);
300 };
301 }
302
303 /// The specified block is found to be reachable, clone it and
304 /// anything that it can reach.
CloneBlock(const BasicBlock * BB,BasicBlock::const_iterator StartingInst,std::vector<const BasicBlock * > & ToClone)305 void PruningFunctionCloner::CloneBlock(const BasicBlock *BB,
306 BasicBlock::const_iterator StartingInst,
307 std::vector<const BasicBlock*> &ToClone){
308 WeakTrackingVH &BBEntry = VMap[BB];
309
310 // Have we already cloned this block?
311 if (BBEntry) return;
312
313 // Nope, clone it now.
314 BasicBlock *NewBB;
315 BBEntry = NewBB = BasicBlock::Create(BB->getContext());
316 if (BB->hasName()) NewBB->setName(BB->getName()+NameSuffix);
317
318 // It is only legal to clone a function if a block address within that
319 // function is never referenced outside of the function. Given that, we
320 // want to map block addresses from the old function to block addresses in
321 // the clone. (This is different from the generic ValueMapper
322 // implementation, which generates an invalid blockaddress when
323 // cloning a function.)
324 //
325 // Note that we don't need to fix the mapping for unreachable blocks;
326 // the default mapping there is safe.
327 if (BB->hasAddressTaken()) {
328 Constant *OldBBAddr = BlockAddress::get(const_cast<Function*>(OldFunc),
329 const_cast<BasicBlock*>(BB));
330 VMap[OldBBAddr] = BlockAddress::get(NewFunc, NewBB);
331 }
332
333 bool hasCalls = false, hasDynamicAllocas = false, hasStaticAllocas = false;
334
335 // Loop over all instructions, and copy them over, DCE'ing as we go. This
336 // loop doesn't include the terminator.
337 for (BasicBlock::const_iterator II = StartingInst, IE = --BB->end();
338 II != IE; ++II) {
339
340 Instruction *NewInst = II->clone();
341
342 // Eagerly remap operands to the newly cloned instruction, except for PHI
343 // nodes for which we defer processing until we update the CFG.
344 if (!isa<PHINode>(NewInst)) {
345 RemapInstruction(NewInst, VMap,
346 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
347
348 // If we can simplify this instruction to some other value, simply add
349 // a mapping to that value rather than inserting a new instruction into
350 // the basic block.
351 if (Value *V =
352 SimplifyInstruction(NewInst, BB->getModule()->getDataLayout())) {
353 // On the off-chance that this simplifies to an instruction in the old
354 // function, map it back into the new function.
355 if (NewFunc != OldFunc)
356 if (Value *MappedV = VMap.lookup(V))
357 V = MappedV;
358
359 if (!NewInst->mayHaveSideEffects()) {
360 VMap[&*II] = V;
361 NewInst->deleteValue();
362 continue;
363 }
364 }
365 }
366
367 if (II->hasName())
368 NewInst->setName(II->getName()+NameSuffix);
369 VMap[&*II] = NewInst; // Add instruction map to value.
370 NewBB->getInstList().push_back(NewInst);
371 hasCalls |= (isa<CallInst>(II) && !isa<DbgInfoIntrinsic>(II));
372
373 if (CodeInfo)
374 if (auto *CB = dyn_cast<CallBase>(&*II))
375 if (CB->hasOperandBundles())
376 CodeInfo->OperandBundleCallSites.push_back(NewInst);
377
378 if (const AllocaInst *AI = dyn_cast<AllocaInst>(II)) {
379 if (isa<ConstantInt>(AI->getArraySize()))
380 hasStaticAllocas = true;
381 else
382 hasDynamicAllocas = true;
383 }
384 }
385
386 // Finally, clone over the terminator.
387 const Instruction *OldTI = BB->getTerminator();
388 bool TerminatorDone = false;
389 if (const BranchInst *BI = dyn_cast<BranchInst>(OldTI)) {
390 if (BI->isConditional()) {
391 // If the condition was a known constant in the callee...
392 ConstantInt *Cond = dyn_cast<ConstantInt>(BI->getCondition());
393 // Or is a known constant in the caller...
394 if (!Cond) {
395 Value *V = VMap.lookup(BI->getCondition());
396 Cond = dyn_cast_or_null<ConstantInt>(V);
397 }
398
399 // Constant fold to uncond branch!
400 if (Cond) {
401 BasicBlock *Dest = BI->getSuccessor(!Cond->getZExtValue());
402 VMap[OldTI] = BranchInst::Create(Dest, NewBB);
403 ToClone.push_back(Dest);
404 TerminatorDone = true;
405 }
406 }
407 } else if (const SwitchInst *SI = dyn_cast<SwitchInst>(OldTI)) {
408 // If switching on a value known constant in the caller.
409 ConstantInt *Cond = dyn_cast<ConstantInt>(SI->getCondition());
410 if (!Cond) { // Or known constant after constant prop in the callee...
411 Value *V = VMap.lookup(SI->getCondition());
412 Cond = dyn_cast_or_null<ConstantInt>(V);
413 }
414 if (Cond) { // Constant fold to uncond branch!
415 SwitchInst::ConstCaseHandle Case = *SI->findCaseValue(Cond);
416 BasicBlock *Dest = const_cast<BasicBlock*>(Case.getCaseSuccessor());
417 VMap[OldTI] = BranchInst::Create(Dest, NewBB);
418 ToClone.push_back(Dest);
419 TerminatorDone = true;
420 }
421 }
422
423 if (!TerminatorDone) {
424 Instruction *NewInst = OldTI->clone();
425 if (OldTI->hasName())
426 NewInst->setName(OldTI->getName()+NameSuffix);
427 NewBB->getInstList().push_back(NewInst);
428 VMap[OldTI] = NewInst; // Add instruction map to value.
429
430 if (CodeInfo)
431 if (auto *CB = dyn_cast<CallBase>(OldTI))
432 if (CB->hasOperandBundles())
433 CodeInfo->OperandBundleCallSites.push_back(NewInst);
434
435 // Recursively clone any reachable successor blocks.
436 const Instruction *TI = BB->getTerminator();
437 for (const BasicBlock *Succ : successors(TI))
438 ToClone.push_back(Succ);
439 }
440
441 if (CodeInfo) {
442 CodeInfo->ContainsCalls |= hasCalls;
443 CodeInfo->ContainsDynamicAllocas |= hasDynamicAllocas;
444 CodeInfo->ContainsDynamicAllocas |= hasStaticAllocas &&
445 BB != &BB->getParent()->front();
446 }
447 }
448
449 /// This works like CloneAndPruneFunctionInto, except that it does not clone the
450 /// entire function. Instead it starts at an instruction provided by the caller
451 /// and copies (and prunes) only the code reachable from that instruction.
CloneAndPruneIntoFromInst(Function * NewFunc,const Function * OldFunc,const Instruction * StartingInst,ValueToValueMapTy & VMap,bool ModuleLevelChanges,SmallVectorImpl<ReturnInst * > & Returns,const char * NameSuffix,ClonedCodeInfo * CodeInfo)452 void llvm::CloneAndPruneIntoFromInst(Function *NewFunc, const Function *OldFunc,
453 const Instruction *StartingInst,
454 ValueToValueMapTy &VMap,
455 bool ModuleLevelChanges,
456 SmallVectorImpl<ReturnInst *> &Returns,
457 const char *NameSuffix,
458 ClonedCodeInfo *CodeInfo) {
459 assert(NameSuffix && "NameSuffix cannot be null!");
460
461 ValueMapTypeRemapper *TypeMapper = nullptr;
462 ValueMaterializer *Materializer = nullptr;
463
464 #ifndef NDEBUG
465 // If the cloning starts at the beginning of the function, verify that
466 // the function arguments are mapped.
467 if (!StartingInst)
468 for (const Argument &II : OldFunc->args())
469 assert(VMap.count(&II) && "No mapping from source argument specified!");
470 #endif
471
472 PruningFunctionCloner PFC(NewFunc, OldFunc, VMap, ModuleLevelChanges,
473 NameSuffix, CodeInfo);
474 const BasicBlock *StartingBB;
475 if (StartingInst)
476 StartingBB = StartingInst->getParent();
477 else {
478 StartingBB = &OldFunc->getEntryBlock();
479 StartingInst = &StartingBB->front();
480 }
481
482 // Clone the entry block, and anything recursively reachable from it.
483 std::vector<const BasicBlock*> CloneWorklist;
484 PFC.CloneBlock(StartingBB, StartingInst->getIterator(), CloneWorklist);
485 while (!CloneWorklist.empty()) {
486 const BasicBlock *BB = CloneWorklist.back();
487 CloneWorklist.pop_back();
488 PFC.CloneBlock(BB, BB->begin(), CloneWorklist);
489 }
490
491 // Loop over all of the basic blocks in the old function. If the block was
492 // reachable, we have cloned it and the old block is now in the value map:
493 // insert it into the new function in the right order. If not, ignore it.
494 //
495 // Defer PHI resolution until rest of function is resolved.
496 SmallVector<const PHINode*, 16> PHIToResolve;
497 for (const BasicBlock &BI : *OldFunc) {
498 Value *V = VMap.lookup(&BI);
499 BasicBlock *NewBB = cast_or_null<BasicBlock>(V);
500 if (!NewBB) continue; // Dead block.
501
502 // Add the new block to the new function.
503 NewFunc->getBasicBlockList().push_back(NewBB);
504
505 // Handle PHI nodes specially, as we have to remove references to dead
506 // blocks.
507 for (const PHINode &PN : BI.phis()) {
508 // PHI nodes may have been remapped to non-PHI nodes by the caller or
509 // during the cloning process.
510 if (isa<PHINode>(VMap[&PN]))
511 PHIToResolve.push_back(&PN);
512 else
513 break;
514 }
515
516 // Finally, remap the terminator instructions, as those can't be remapped
517 // until all BBs are mapped.
518 RemapInstruction(NewBB->getTerminator(), VMap,
519 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges,
520 TypeMapper, Materializer);
521 }
522
523 // Defer PHI resolution until rest of function is resolved, PHI resolution
524 // requires the CFG to be up-to-date.
525 for (unsigned phino = 0, e = PHIToResolve.size(); phino != e; ) {
526 const PHINode *OPN = PHIToResolve[phino];
527 unsigned NumPreds = OPN->getNumIncomingValues();
528 const BasicBlock *OldBB = OPN->getParent();
529 BasicBlock *NewBB = cast<BasicBlock>(VMap[OldBB]);
530
531 // Map operands for blocks that are live and remove operands for blocks
532 // that are dead.
533 for (; phino != PHIToResolve.size() &&
534 PHIToResolve[phino]->getParent() == OldBB; ++phino) {
535 OPN = PHIToResolve[phino];
536 PHINode *PN = cast<PHINode>(VMap[OPN]);
537 for (unsigned pred = 0, e = NumPreds; pred != e; ++pred) {
538 Value *V = VMap.lookup(PN->getIncomingBlock(pred));
539 if (BasicBlock *MappedBlock = cast_or_null<BasicBlock>(V)) {
540 Value *InVal = MapValue(PN->getIncomingValue(pred),
541 VMap,
542 ModuleLevelChanges ? RF_None : RF_NoModuleLevelChanges);
543 assert(InVal && "Unknown input value?");
544 PN->setIncomingValue(pred, InVal);
545 PN->setIncomingBlock(pred, MappedBlock);
546 } else {
547 PN->removeIncomingValue(pred, false);
548 --pred; // Revisit the next entry.
549 --e;
550 }
551 }
552 }
553
554 // The loop above has removed PHI entries for those blocks that are dead
555 // and has updated others. However, if a block is live (i.e. copied over)
556 // but its terminator has been changed to not go to this block, then our
557 // phi nodes will have invalid entries. Update the PHI nodes in this
558 // case.
559 PHINode *PN = cast<PHINode>(NewBB->begin());
560 NumPreds = pred_size(NewBB);
561 if (NumPreds != PN->getNumIncomingValues()) {
562 assert(NumPreds < PN->getNumIncomingValues());
563 // Count how many times each predecessor comes to this block.
564 std::map<BasicBlock*, unsigned> PredCount;
565 for (pred_iterator PI = pred_begin(NewBB), E = pred_end(NewBB);
566 PI != E; ++PI)
567 --PredCount[*PI];
568
569 // Figure out how many entries to remove from each PHI.
570 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
571 ++PredCount[PN->getIncomingBlock(i)];
572
573 // At this point, the excess predecessor entries are positive in the
574 // map. Loop over all of the PHIs and remove excess predecessor
575 // entries.
576 BasicBlock::iterator I = NewBB->begin();
577 for (; (PN = dyn_cast<PHINode>(I)); ++I) {
578 for (const auto &PCI : PredCount) {
579 BasicBlock *Pred = PCI.first;
580 for (unsigned NumToRemove = PCI.second; NumToRemove; --NumToRemove)
581 PN->removeIncomingValue(Pred, false);
582 }
583 }
584 }
585
586 // If the loops above have made these phi nodes have 0 or 1 operand,
587 // replace them with undef or the input value. We must do this for
588 // correctness, because 0-operand phis are not valid.
589 PN = cast<PHINode>(NewBB->begin());
590 if (PN->getNumIncomingValues() == 0) {
591 BasicBlock::iterator I = NewBB->begin();
592 BasicBlock::const_iterator OldI = OldBB->begin();
593 while ((PN = dyn_cast<PHINode>(I++))) {
594 Value *NV = UndefValue::get(PN->getType());
595 PN->replaceAllUsesWith(NV);
596 assert(VMap[&*OldI] == PN && "VMap mismatch");
597 VMap[&*OldI] = NV;
598 PN->eraseFromParent();
599 ++OldI;
600 }
601 }
602 }
603
604 // Make a second pass over the PHINodes now that all of them have been
605 // remapped into the new function, simplifying the PHINode and performing any
606 // recursive simplifications exposed. This will transparently update the
607 // WeakTrackingVH in the VMap. Notably, we rely on that so that if we coalesce
608 // two PHINodes, the iteration over the old PHIs remains valid, and the
609 // mapping will just map us to the new node (which may not even be a PHI
610 // node).
611 const DataLayout &DL = NewFunc->getParent()->getDataLayout();
612 SmallSetVector<const Value *, 8> Worklist;
613 for (unsigned Idx = 0, Size = PHIToResolve.size(); Idx != Size; ++Idx)
614 if (isa<PHINode>(VMap[PHIToResolve[Idx]]))
615 Worklist.insert(PHIToResolve[Idx]);
616
617 // Note that we must test the size on each iteration, the worklist can grow.
618 for (unsigned Idx = 0; Idx != Worklist.size(); ++Idx) {
619 const Value *OrigV = Worklist[Idx];
620 auto *I = dyn_cast_or_null<Instruction>(VMap.lookup(OrigV));
621 if (!I)
622 continue;
623
624 // Skip over non-intrinsic callsites, we don't want to remove any nodes from
625 // the CGSCC.
626 CallBase *CB = dyn_cast<CallBase>(I);
627 if (CB && CB->getCalledFunction() &&
628 !CB->getCalledFunction()->isIntrinsic())
629 continue;
630
631 // See if this instruction simplifies.
632 Value *SimpleV = SimplifyInstruction(I, DL);
633 if (!SimpleV)
634 continue;
635
636 // Stash away all the uses of the old instruction so we can check them for
637 // recursive simplifications after a RAUW. This is cheaper than checking all
638 // uses of To on the recursive step in most cases.
639 for (const User *U : OrigV->users())
640 Worklist.insert(cast<Instruction>(U));
641
642 // Replace the instruction with its simplified value.
643 I->replaceAllUsesWith(SimpleV);
644
645 // If the original instruction had no side effects, remove it.
646 if (isInstructionTriviallyDead(I))
647 I->eraseFromParent();
648 else
649 VMap[OrigV] = I;
650 }
651
652 // Now that the inlined function body has been fully constructed, go through
653 // and zap unconditional fall-through branches. This happens all the time when
654 // specializing code: code specialization turns conditional branches into
655 // uncond branches, and this code folds them.
656 Function::iterator Begin = cast<BasicBlock>(VMap[StartingBB])->getIterator();
657 Function::iterator I = Begin;
658 while (I != NewFunc->end()) {
659 // We need to simplify conditional branches and switches with a constant
660 // operand. We try to prune these out when cloning, but if the
661 // simplification required looking through PHI nodes, those are only
662 // available after forming the full basic block. That may leave some here,
663 // and we still want to prune the dead code as early as possible.
664 //
665 // Do the folding before we check if the block is dead since we want code
666 // like
667 // bb:
668 // br i1 undef, label %bb, label %bb
669 // to be simplified to
670 // bb:
671 // br label %bb
672 // before we call I->getSinglePredecessor().
673 ConstantFoldTerminator(&*I);
674
675 // Check if this block has become dead during inlining or other
676 // simplifications. Note that the first block will appear dead, as it has
677 // not yet been wired up properly.
678 if (I != Begin && (pred_empty(&*I) || I->getSinglePredecessor() == &*I)) {
679 BasicBlock *DeadBB = &*I++;
680 DeleteDeadBlock(DeadBB);
681 continue;
682 }
683
684 BranchInst *BI = dyn_cast<BranchInst>(I->getTerminator());
685 if (!BI || BI->isConditional()) { ++I; continue; }
686
687 BasicBlock *Dest = BI->getSuccessor(0);
688 if (!Dest->getSinglePredecessor()) {
689 ++I; continue;
690 }
691
692 // We shouldn't be able to get single-entry PHI nodes here, as instsimplify
693 // above should have zapped all of them..
694 assert(!isa<PHINode>(Dest->begin()));
695
696 // We know all single-entry PHI nodes in the inlined function have been
697 // removed, so we just need to splice the blocks.
698 BI->eraseFromParent();
699
700 // Make all PHI nodes that referred to Dest now refer to I as their source.
701 Dest->replaceAllUsesWith(&*I);
702
703 // Move all the instructions in the succ to the pred.
704 I->getInstList().splice(I->end(), Dest->getInstList());
705
706 // Remove the dest block.
707 Dest->eraseFromParent();
708
709 // Do not increment I, iteratively merge all things this block branches to.
710 }
711
712 // Make a final pass over the basic blocks from the old function to gather
713 // any return instructions which survived folding. We have to do this here
714 // because we can iteratively remove and merge returns above.
715 for (Function::iterator I = cast<BasicBlock>(VMap[StartingBB])->getIterator(),
716 E = NewFunc->end();
717 I != E; ++I)
718 if (ReturnInst *RI = dyn_cast<ReturnInst>(I->getTerminator()))
719 Returns.push_back(RI);
720 }
721
722
723 /// This works exactly like CloneFunctionInto,
724 /// except that it does some simple constant prop and DCE on the fly. The
725 /// effect of this is to copy significantly less code in cases where (for
726 /// example) a function call with constant arguments is inlined, and those
727 /// constant arguments cause a significant amount of code in the callee to be
728 /// dead. Since this doesn't produce an exact copy of the input, it can't be
729 /// used for things like CloneFunction or CloneModule.
CloneAndPruneFunctionInto(Function * NewFunc,const Function * OldFunc,ValueToValueMapTy & VMap,bool ModuleLevelChanges,SmallVectorImpl<ReturnInst * > & Returns,const char * NameSuffix,ClonedCodeInfo * CodeInfo,Instruction * TheCall)730 void llvm::CloneAndPruneFunctionInto(Function *NewFunc, const Function *OldFunc,
731 ValueToValueMapTy &VMap,
732 bool ModuleLevelChanges,
733 SmallVectorImpl<ReturnInst*> &Returns,
734 const char *NameSuffix,
735 ClonedCodeInfo *CodeInfo,
736 Instruction *TheCall) {
737 CloneAndPruneIntoFromInst(NewFunc, OldFunc, &OldFunc->front().front(), VMap,
738 ModuleLevelChanges, Returns, NameSuffix, CodeInfo);
739 }
740
741 /// Remaps instructions in \p Blocks using the mapping in \p VMap.
remapInstructionsInBlocks(const SmallVectorImpl<BasicBlock * > & Blocks,ValueToValueMapTy & VMap)742 void llvm::remapInstructionsInBlocks(
743 const SmallVectorImpl<BasicBlock *> &Blocks, ValueToValueMapTy &VMap) {
744 // Rewrite the code to refer to itself.
745 for (auto *BB : Blocks)
746 for (auto &Inst : *BB)
747 RemapInstruction(&Inst, VMap,
748 RF_NoModuleLevelChanges | RF_IgnoreMissingLocals);
749 }
750
751 /// Clones a loop \p OrigLoop. Returns the loop and the blocks in \p
752 /// Blocks.
753 ///
754 /// Updates LoopInfo and DominatorTree assuming the loop is dominated by block
755 /// \p LoopDomBB. Insert the new blocks before block specified in \p Before.
cloneLoopWithPreheader(BasicBlock * Before,BasicBlock * LoopDomBB,Loop * OrigLoop,ValueToValueMapTy & VMap,const Twine & NameSuffix,LoopInfo * LI,DominatorTree * DT,SmallVectorImpl<BasicBlock * > & Blocks)756 Loop *llvm::cloneLoopWithPreheader(BasicBlock *Before, BasicBlock *LoopDomBB,
757 Loop *OrigLoop, ValueToValueMapTy &VMap,
758 const Twine &NameSuffix, LoopInfo *LI,
759 DominatorTree *DT,
760 SmallVectorImpl<BasicBlock *> &Blocks) {
761 Function *F = OrigLoop->getHeader()->getParent();
762 Loop *ParentLoop = OrigLoop->getParentLoop();
763 DenseMap<Loop *, Loop *> LMap;
764
765 Loop *NewLoop = LI->AllocateLoop();
766 LMap[OrigLoop] = NewLoop;
767 if (ParentLoop)
768 ParentLoop->addChildLoop(NewLoop);
769 else
770 LI->addTopLevelLoop(NewLoop);
771
772 BasicBlock *OrigPH = OrigLoop->getLoopPreheader();
773 assert(OrigPH && "No preheader");
774 BasicBlock *NewPH = CloneBasicBlock(OrigPH, VMap, NameSuffix, F);
775 // To rename the loop PHIs.
776 VMap[OrigPH] = NewPH;
777 Blocks.push_back(NewPH);
778
779 // Update LoopInfo.
780 if (ParentLoop)
781 ParentLoop->addBasicBlockToLoop(NewPH, *LI);
782
783 // Update DominatorTree.
784 DT->addNewBlock(NewPH, LoopDomBB);
785
786 for (Loop *CurLoop : OrigLoop->getLoopsInPreorder()) {
787 Loop *&NewLoop = LMap[CurLoop];
788 if (!NewLoop) {
789 NewLoop = LI->AllocateLoop();
790
791 // Establish the parent/child relationship.
792 Loop *OrigParent = CurLoop->getParentLoop();
793 assert(OrigParent && "Could not find the original parent loop");
794 Loop *NewParentLoop = LMap[OrigParent];
795 assert(NewParentLoop && "Could not find the new parent loop");
796
797 NewParentLoop->addChildLoop(NewLoop);
798 }
799 }
800
801 for (BasicBlock *BB : OrigLoop->getBlocks()) {
802 Loop *CurLoop = LI->getLoopFor(BB);
803 Loop *&NewLoop = LMap[CurLoop];
804 assert(NewLoop && "Expecting new loop to be allocated");
805
806 BasicBlock *NewBB = CloneBasicBlock(BB, VMap, NameSuffix, F);
807 VMap[BB] = NewBB;
808
809 // Update LoopInfo.
810 NewLoop->addBasicBlockToLoop(NewBB, *LI);
811
812 // Add DominatorTree node. After seeing all blocks, update to correct
813 // IDom.
814 DT->addNewBlock(NewBB, NewPH);
815
816 Blocks.push_back(NewBB);
817 }
818
819 for (BasicBlock *BB : OrigLoop->getBlocks()) {
820 // Update loop headers.
821 Loop *CurLoop = LI->getLoopFor(BB);
822 if (BB == CurLoop->getHeader())
823 LMap[CurLoop]->moveToHeader(cast<BasicBlock>(VMap[BB]));
824
825 // Update DominatorTree.
826 BasicBlock *IDomBB = DT->getNode(BB)->getIDom()->getBlock();
827 DT->changeImmediateDominator(cast<BasicBlock>(VMap[BB]),
828 cast<BasicBlock>(VMap[IDomBB]));
829 }
830
831 // Move them physically from the end of the block list.
832 F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(),
833 NewPH);
834 F->getBasicBlockList().splice(Before->getIterator(), F->getBasicBlockList(),
835 NewLoop->getHeader()->getIterator(), F->end());
836
837 return NewLoop;
838 }
839
840 /// Duplicate non-Phi instructions from the beginning of block up to
841 /// StopAt instruction into a split block between BB and its predecessor.
DuplicateInstructionsInSplitBetween(BasicBlock * BB,BasicBlock * PredBB,Instruction * StopAt,ValueToValueMapTy & ValueMapping,DomTreeUpdater & DTU)842 BasicBlock *llvm::DuplicateInstructionsInSplitBetween(
843 BasicBlock *BB, BasicBlock *PredBB, Instruction *StopAt,
844 ValueToValueMapTy &ValueMapping, DomTreeUpdater &DTU) {
845
846 assert(count(successors(PredBB), BB) == 1 &&
847 "There must be a single edge between PredBB and BB!");
848 // We are going to have to map operands from the original BB block to the new
849 // copy of the block 'NewBB'. If there are PHI nodes in BB, evaluate them to
850 // account for entry from PredBB.
851 BasicBlock::iterator BI = BB->begin();
852 for (; PHINode *PN = dyn_cast<PHINode>(BI); ++BI)
853 ValueMapping[PN] = PN->getIncomingValueForBlock(PredBB);
854
855 BasicBlock *NewBB = SplitEdge(PredBB, BB);
856 NewBB->setName(PredBB->getName() + ".split");
857 Instruction *NewTerm = NewBB->getTerminator();
858
859 // FIXME: SplitEdge does not yet take a DTU, so we include the split edge
860 // in the update set here.
861 DTU.applyUpdates({{DominatorTree::Delete, PredBB, BB},
862 {DominatorTree::Insert, PredBB, NewBB},
863 {DominatorTree::Insert, NewBB, BB}});
864
865 // Clone the non-phi instructions of BB into NewBB, keeping track of the
866 // mapping and using it to remap operands in the cloned instructions.
867 // Stop once we see the terminator too. This covers the case where BB's
868 // terminator gets replaced and StopAt == BB's terminator.
869 for (; StopAt != &*BI && BB->getTerminator() != &*BI; ++BI) {
870 Instruction *New = BI->clone();
871 New->setName(BI->getName());
872 New->insertBefore(NewTerm);
873 ValueMapping[&*BI] = New;
874
875 // Remap operands to patch up intra-block references.
876 for (unsigned i = 0, e = New->getNumOperands(); i != e; ++i)
877 if (Instruction *Inst = dyn_cast<Instruction>(New->getOperand(i))) {
878 auto I = ValueMapping.find(Inst);
879 if (I != ValueMapping.end())
880 New->setOperand(i, I->second);
881 }
882 }
883
884 return NewBB;
885 }
886