1 //===- CodeExtractor.cpp - Pull code region into a new 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 interface to tear out a code region, such as an
11 // individual loop or a parallel section, into a new function, replacing it with
12 // a call to the new function.
14 //===----------------------------------------------------------------------===//
16 #include "llvm/Transforms/Utils/FunctionUtils.h"
17 #include "llvm/Constants.h"
18 #include "llvm/DerivedTypes.h"
19 #include "llvm/Instructions.h"
20 #include "llvm/Intrinsics.h"
21 #include "llvm/LLVMContext.h"
22 #include "llvm/Module.h"
23 #include "llvm/Pass.h"
24 #include "llvm/Analysis/Dominators.h"
25 #include "llvm/Analysis/LoopInfo.h"
26 #include "llvm/Analysis/Verifier.h"
27 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
28 #include "llvm/Support/CommandLine.h"
29 #include "llvm/Support/Compiler.h"
30 #include "llvm/Support/Debug.h"
31 #include "llvm/Support/ErrorHandling.h"
32 #include "llvm/Support/raw_ostream.h"
33 #include "llvm/ADT/StringExtras.h"
38 // Provide a command-line option to aggregate function arguments into a struct
39 // for functions produced by the code extractor. This is useful when converting
40 // extracted functions to pthread-based code, as only one argument (void*) can
41 // be passed in to pthread_create().
43 AggregateArgsOpt("aggregate-extracted-args", cl::Hidden,
44 cl::desc("Aggregate arguments to code-extracted functions"));
47 class VISIBILITY_HIDDEN CodeExtractor {
48 typedef std::vector<Value*> Values;
49 std::set<BasicBlock*> BlocksToExtract;
52 unsigned NumExitBlocks;
55 CodeExtractor(DominatorTree* dt = 0, bool AggArgs = false)
56 : DT(dt), AggregateArgs(AggArgs||AggregateArgsOpt), NumExitBlocks(~0U) {}
58 Function *ExtractCodeRegion(const std::vector<BasicBlock*> &code);
60 bool isEligible(const std::vector<BasicBlock*> &code);
63 /// definedInRegion - Return true if the specified value is defined in the
65 bool definedInRegion(Value *V) const {
66 if (Instruction *I = dyn_cast<Instruction>(V))
67 if (BlocksToExtract.count(I->getParent()))
72 /// definedInCaller - Return true if the specified value is defined in the
73 /// function being code extracted, but not in the region being extracted.
74 /// These values must be passed in as live-ins to the function.
75 bool definedInCaller(Value *V) const {
76 if (isa<Argument>(V)) return true;
77 if (Instruction *I = dyn_cast<Instruction>(V))
78 if (!BlocksToExtract.count(I->getParent()))
83 void severSplitPHINodes(BasicBlock *&Header);
84 void splitReturnBlocks();
85 void findInputsOutputs(Values &inputs, Values &outputs);
87 Function *constructFunction(const Values &inputs,
88 const Values &outputs,
90 BasicBlock *newRootNode, BasicBlock *newHeader,
91 Function *oldFunction, Module *M);
93 void moveCodeToFunction(Function *newFunction);
95 void emitCallAndSwitchStatement(Function *newFunction,
96 BasicBlock *newHeader,
103 /// severSplitPHINodes - If a PHI node has multiple inputs from outside of the
104 /// region, we need to split the entry block of the region so that the PHI node
105 /// is easier to deal with.
106 void CodeExtractor::severSplitPHINodes(BasicBlock *&Header) {
107 bool HasPredsFromRegion = false;
108 unsigned NumPredsOutsideRegion = 0;
110 if (Header != &Header->getParent()->getEntryBlock()) {
111 PHINode *PN = dyn_cast<PHINode>(Header->begin());
112 if (!PN) return; // No PHI nodes.
114 // If the header node contains any PHI nodes, check to see if there is more
115 // than one entry from outside the region. If so, we need to sever the
116 // header block into two.
117 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
118 if (BlocksToExtract.count(PN->getIncomingBlock(i)))
119 HasPredsFromRegion = true;
121 ++NumPredsOutsideRegion;
123 // If there is one (or fewer) predecessor from outside the region, we don't
124 // need to do anything special.
125 if (NumPredsOutsideRegion <= 1) return;
128 // Otherwise, we need to split the header block into two pieces: one
129 // containing PHI nodes merging values from outside of the region, and a
130 // second that contains all of the code for the block and merges back any
131 // incoming values from inside of the region.
132 BasicBlock::iterator AfterPHIs = Header->getFirstNonPHI();
133 BasicBlock *NewBB = Header->splitBasicBlock(AfterPHIs,
134 Header->getName()+".ce");
136 // We only want to code extract the second block now, and it becomes the new
137 // header of the region.
138 BasicBlock *OldPred = Header;
139 BlocksToExtract.erase(OldPred);
140 BlocksToExtract.insert(NewBB);
143 // Okay, update dominator sets. The blocks that dominate the new one are the
144 // blocks that dominate TIBB plus the new block itself.
146 DT->splitBlock(NewBB);
148 // Okay, now we need to adjust the PHI nodes and any branches from within the
149 // region to go to the new header block instead of the old header block.
150 if (HasPredsFromRegion) {
151 PHINode *PN = cast<PHINode>(OldPred->begin());
152 // Loop over all of the predecessors of OldPred that are in the region,
153 // changing them to branch to NewBB instead.
154 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
155 if (BlocksToExtract.count(PN->getIncomingBlock(i))) {
156 TerminatorInst *TI = PN->getIncomingBlock(i)->getTerminator();
157 TI->replaceUsesOfWith(OldPred, NewBB);
160 // Okay, everthing within the region is now branching to the right block, we
161 // just have to update the PHI nodes now, inserting PHI nodes into NewBB.
162 for (AfterPHIs = OldPred->begin(); isa<PHINode>(AfterPHIs); ++AfterPHIs) {
163 PHINode *PN = cast<PHINode>(AfterPHIs);
164 // Create a new PHI node in the new region, which has an incoming value
165 // from OldPred of PN.
166 PHINode *NewPN = PHINode::Create(PN->getType(), PN->getName()+".ce",
168 NewPN->addIncoming(PN, OldPred);
170 // Loop over all of the incoming value in PN, moving them to NewPN if they
171 // are from the extracted region.
172 for (unsigned i = 0; i != PN->getNumIncomingValues(); ++i) {
173 if (BlocksToExtract.count(PN->getIncomingBlock(i))) {
174 NewPN->addIncoming(PN->getIncomingValue(i), PN->getIncomingBlock(i));
175 PN->removeIncomingValue(i);
183 void CodeExtractor::splitReturnBlocks() {
184 for (std::set<BasicBlock*>::iterator I = BlocksToExtract.begin(),
185 E = BlocksToExtract.end(); I != E; ++I)
186 if (ReturnInst *RI = dyn_cast<ReturnInst>((*I)->getTerminator()))
187 (*I)->splitBasicBlock(RI, (*I)->getName()+".ret");
190 // findInputsOutputs - Find inputs to, outputs from the code region.
192 void CodeExtractor::findInputsOutputs(Values &inputs, Values &outputs) {
193 std::set<BasicBlock*> ExitBlocks;
194 for (std::set<BasicBlock*>::const_iterator ci = BlocksToExtract.begin(),
195 ce = BlocksToExtract.end(); ci != ce; ++ci) {
196 BasicBlock *BB = *ci;
198 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
199 // If a used value is defined outside the region, it's an input. If an
200 // instruction is used outside the region, it's an output.
201 for (User::op_iterator O = I->op_begin(), E = I->op_end(); O != E; ++O)
202 if (definedInCaller(*O))
203 inputs.push_back(*O);
205 // Consider uses of this instruction (outputs).
206 for (Value::use_iterator UI = I->use_begin(), E = I->use_end();
208 if (!definedInRegion(*UI)) {
209 outputs.push_back(I);
214 // Keep track of the exit blocks from the region.
215 TerminatorInst *TI = BB->getTerminator();
216 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
217 if (!BlocksToExtract.count(TI->getSuccessor(i)))
218 ExitBlocks.insert(TI->getSuccessor(i));
219 } // for: basic blocks
221 NumExitBlocks = ExitBlocks.size();
223 // Eliminate duplicates.
224 std::sort(inputs.begin(), inputs.end());
225 inputs.erase(std::unique(inputs.begin(), inputs.end()), inputs.end());
226 std::sort(outputs.begin(), outputs.end());
227 outputs.erase(std::unique(outputs.begin(), outputs.end()), outputs.end());
230 /// constructFunction - make a function based on inputs and outputs, as follows:
231 /// f(in0, ..., inN, out0, ..., outN)
233 Function *CodeExtractor::constructFunction(const Values &inputs,
234 const Values &outputs,
236 BasicBlock *newRootNode,
237 BasicBlock *newHeader,
238 Function *oldFunction,
240 DEBUG(errs() << "inputs: " << inputs.size() << "\n");
241 DEBUG(errs() << "outputs: " << outputs.size() << "\n");
243 // This function returns unsigned, outputs will go back by reference.
244 switch (NumExitBlocks) {
246 case 1: RetTy = Type::getVoidTy(header->getContext()); break;
247 case 2: RetTy = Type::getInt1Ty(header->getContext()); break;
248 default: RetTy = Type::getInt16Ty(header->getContext()); break;
251 std::vector<const Type*> paramTy;
253 // Add the types of the input values to the function's argument list
254 for (Values::const_iterator i = inputs.begin(),
255 e = inputs.end(); i != e; ++i) {
256 const Value *value = *i;
257 DEBUG(errs() << "value used in func: " << *value << "\n");
258 paramTy.push_back(value->getType());
261 // Add the types of the output values to the function's argument list.
262 for (Values::const_iterator I = outputs.begin(), E = outputs.end();
264 DEBUG(errs() << "instr used in func: " << **I << "\n");
266 paramTy.push_back((*I)->getType());
268 paramTy.push_back(PointerType::getUnqual((*I)->getType()));
271 DEBUG(errs() << "Function type: " << *RetTy << " f(");
272 for (std::vector<const Type*>::iterator i = paramTy.begin(),
273 e = paramTy.end(); i != e; ++i)
274 DEBUG(errs() << **i << ", ");
275 DEBUG(errs() << ")\n");
277 if (AggregateArgs && (inputs.size() + outputs.size() > 0)) {
278 PointerType *StructPtr =
279 PointerType::getUnqual(StructType::get(M->getContext(), paramTy));
281 paramTy.push_back(StructPtr);
283 const FunctionType *funcType =
284 FunctionType::get(RetTy, paramTy, false);
286 // Create the new function
287 Function *newFunction = Function::Create(funcType,
288 GlobalValue::InternalLinkage,
289 oldFunction->getName() + "_" +
290 header->getName(), M);
291 // If the old function is no-throw, so is the new one.
292 if (oldFunction->doesNotThrow())
293 newFunction->setDoesNotThrow(true);
295 newFunction->getBasicBlockList().push_back(newRootNode);
297 // Create an iterator to name all of the arguments we inserted.
298 Function::arg_iterator AI = newFunction->arg_begin();
300 // Rewrite all users of the inputs in the extracted region to use the
301 // arguments (or appropriate addressing into struct) instead.
302 for (unsigned i = 0, e = inputs.size(); i != e; ++i) {
306 Idx[0] = Constant::getNullValue(Type::getInt32Ty(header->getContext()));
307 Idx[1] = ConstantInt::get(Type::getInt32Ty(header->getContext()), i);
308 TerminatorInst *TI = newFunction->begin()->getTerminator();
309 GetElementPtrInst *GEP =
310 GetElementPtrInst::Create(AI, Idx, Idx+2,
311 "gep_" + inputs[i]->getName(), TI);
312 RewriteVal = new LoadInst(GEP, "loadgep_" + inputs[i]->getName(), TI);
316 std::vector<User*> Users(inputs[i]->use_begin(), inputs[i]->use_end());
317 for (std::vector<User*>::iterator use = Users.begin(), useE = Users.end();
319 if (Instruction* inst = dyn_cast<Instruction>(*use))
320 if (BlocksToExtract.count(inst->getParent()))
321 inst->replaceUsesOfWith(inputs[i], RewriteVal);
324 // Set names for input and output arguments.
325 if (!AggregateArgs) {
326 AI = newFunction->arg_begin();
327 for (unsigned i = 0, e = inputs.size(); i != e; ++i, ++AI)
328 AI->setName(inputs[i]->getName());
329 for (unsigned i = 0, e = outputs.size(); i != e; ++i, ++AI)
330 AI->setName(outputs[i]->getName()+".out");
333 // Rewrite branches to basic blocks outside of the loop to new dummy blocks
334 // within the new function. This must be done before we lose track of which
335 // blocks were originally in the code region.
336 std::vector<User*> Users(header->use_begin(), header->use_end());
337 for (unsigned i = 0, e = Users.size(); i != e; ++i)
338 // The BasicBlock which contains the branch is not in the region
339 // modify the branch target to a new block
340 if (TerminatorInst *TI = dyn_cast<TerminatorInst>(Users[i]))
341 if (!BlocksToExtract.count(TI->getParent()) &&
342 TI->getParent()->getParent() == oldFunction)
343 TI->replaceUsesOfWith(header, newHeader);
348 /// emitCallAndSwitchStatement - This method sets up the caller side by adding
349 /// the call instruction, splitting any PHI nodes in the header block as
352 emitCallAndSwitchStatement(Function *newFunction, BasicBlock *codeReplacer,
353 Values &inputs, Values &outputs) {
354 // Emit a call to the new function, passing in: *pointer to struct (if
355 // aggregating parameters), or plan inputs and allocated memory for outputs
356 std::vector<Value*> params, StructValues, ReloadOutputs;
358 LLVMContext &Context = newFunction->getContext();
360 // Add inputs as params, or to be filled into the struct
361 for (Values::iterator i = inputs.begin(), e = inputs.end(); i != e; ++i)
363 StructValues.push_back(*i);
365 params.push_back(*i);
367 // Create allocas for the outputs
368 for (Values::iterator i = outputs.begin(), e = outputs.end(); i != e; ++i) {
370 StructValues.push_back(*i);
373 new AllocaInst((*i)->getType(), 0, (*i)->getName()+".loc",
374 codeReplacer->getParent()->begin()->begin());
375 ReloadOutputs.push_back(alloca);
376 params.push_back(alloca);
380 AllocaInst *Struct = 0;
381 if (AggregateArgs && (inputs.size() + outputs.size() > 0)) {
382 std::vector<const Type*> ArgTypes;
383 for (Values::iterator v = StructValues.begin(),
384 ve = StructValues.end(); v != ve; ++v)
385 ArgTypes.push_back((*v)->getType());
387 // Allocate a struct at the beginning of this function
388 Type *StructArgTy = StructType::get(newFunction->getContext(), ArgTypes);
390 new AllocaInst(StructArgTy, 0, "structArg",
391 codeReplacer->getParent()->begin()->begin());
392 params.push_back(Struct);
394 for (unsigned i = 0, e = inputs.size(); i != e; ++i) {
396 Idx[0] = Constant::getNullValue(Type::getInt32Ty(Context));
397 Idx[1] = ConstantInt::get(Type::getInt32Ty(Context), i);
398 GetElementPtrInst *GEP =
399 GetElementPtrInst::Create(Struct, Idx, Idx + 2,
400 "gep_" + StructValues[i]->getName());
401 codeReplacer->getInstList().push_back(GEP);
402 StoreInst *SI = new StoreInst(StructValues[i], GEP);
403 codeReplacer->getInstList().push_back(SI);
407 // Emit the call to the function
408 CallInst *call = CallInst::Create(newFunction, params.begin(), params.end(),
409 NumExitBlocks > 1 ? "targetBlock" : "");
410 codeReplacer->getInstList().push_back(call);
412 Function::arg_iterator OutputArgBegin = newFunction->arg_begin();
413 unsigned FirstOut = inputs.size();
415 std::advance(OutputArgBegin, inputs.size());
417 // Reload the outputs passed in by reference
418 for (unsigned i = 0, e = outputs.size(); i != e; ++i) {
422 Idx[0] = Constant::getNullValue(Type::getInt32Ty(Context));
423 Idx[1] = ConstantInt::get(Type::getInt32Ty(Context), FirstOut + i);
424 GetElementPtrInst *GEP
425 = GetElementPtrInst::Create(Struct, Idx, Idx + 2,
426 "gep_reload_" + outputs[i]->getName());
427 codeReplacer->getInstList().push_back(GEP);
430 Output = ReloadOutputs[i];
432 LoadInst *load = new LoadInst(Output, outputs[i]->getName()+".reload");
433 codeReplacer->getInstList().push_back(load);
434 std::vector<User*> Users(outputs[i]->use_begin(), outputs[i]->use_end());
435 for (unsigned u = 0, e = Users.size(); u != e; ++u) {
436 Instruction *inst = cast<Instruction>(Users[u]);
437 if (!BlocksToExtract.count(inst->getParent()))
438 inst->replaceUsesOfWith(outputs[i], load);
442 // Now we can emit a switch statement using the call as a value.
443 SwitchInst *TheSwitch =
444 SwitchInst::Create(Constant::getNullValue(Type::getInt16Ty(Context)),
445 codeReplacer, 0, codeReplacer);
447 // Since there may be multiple exits from the original region, make the new
448 // function return an unsigned, switch on that number. This loop iterates
449 // over all of the blocks in the extracted region, updating any terminator
450 // instructions in the to-be-extracted region that branch to blocks that are
451 // not in the region to be extracted.
452 std::map<BasicBlock*, BasicBlock*> ExitBlockMap;
454 unsigned switchVal = 0;
455 for (std::set<BasicBlock*>::const_iterator i = BlocksToExtract.begin(),
456 e = BlocksToExtract.end(); i != e; ++i) {
457 TerminatorInst *TI = (*i)->getTerminator();
458 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
459 if (!BlocksToExtract.count(TI->getSuccessor(i))) {
460 BasicBlock *OldTarget = TI->getSuccessor(i);
461 // add a new basic block which returns the appropriate value
462 BasicBlock *&NewTarget = ExitBlockMap[OldTarget];
464 // If we don't already have an exit stub for this non-extracted
465 // destination, create one now!
466 NewTarget = BasicBlock::Create(Context,
467 OldTarget->getName() + ".exitStub",
469 unsigned SuccNum = switchVal++;
472 switch (NumExitBlocks) {
474 case 1: break; // No value needed.
475 case 2: // Conditional branch, return a bool
476 brVal = ConstantInt::get(Type::getInt1Ty(Context), !SuccNum);
479 brVal = ConstantInt::get(Type::getInt16Ty(Context), SuccNum);
483 ReturnInst *NTRet = ReturnInst::Create(Context, brVal, NewTarget);
485 // Update the switch instruction.
486 TheSwitch->addCase(ConstantInt::get(Type::getInt16Ty(Context),
490 // Restore values just before we exit
491 Function::arg_iterator OAI = OutputArgBegin;
492 for (unsigned out = 0, e = outputs.size(); out != e; ++out) {
493 // For an invoke, the normal destination is the only one that is
494 // dominated by the result of the invocation
495 BasicBlock *DefBlock = cast<Instruction>(outputs[out])->getParent();
497 bool DominatesDef = true;
499 if (InvokeInst *Invoke = dyn_cast<InvokeInst>(outputs[out])) {
500 DefBlock = Invoke->getNormalDest();
502 // Make sure we are looking at the original successor block, not
503 // at a newly inserted exit block, which won't be in the dominator
505 for (std::map<BasicBlock*, BasicBlock*>::iterator I =
506 ExitBlockMap.begin(), E = ExitBlockMap.end(); I != E; ++I)
507 if (DefBlock == I->second) {
512 // In the extract block case, if the block we are extracting ends
513 // with an invoke instruction, make sure that we don't emit a
514 // store of the invoke value for the unwind block.
515 if (!DT && DefBlock != OldTarget)
516 DominatesDef = false;
520 DominatesDef = DT->dominates(DefBlock, OldTarget);
525 Idx[0] = Constant::getNullValue(Type::getInt32Ty(Context));
526 Idx[1] = ConstantInt::get(Type::getInt32Ty(Context),
528 GetElementPtrInst *GEP =
529 GetElementPtrInst::Create(OAI, Idx, Idx + 2,
530 "gep_" + outputs[out]->getName(),
532 new StoreInst(outputs[out], GEP, NTRet);
534 new StoreInst(outputs[out], OAI, NTRet);
537 // Advance output iterator even if we don't emit a store
538 if (!AggregateArgs) ++OAI;
542 // rewrite the original branch instruction with this new target
543 TI->setSuccessor(i, NewTarget);
547 // Now that we've done the deed, simplify the switch instruction.
548 const Type *OldFnRetTy = TheSwitch->getParent()->getParent()->getReturnType();
549 switch (NumExitBlocks) {
551 // There are no successors (the block containing the switch itself), which
552 // means that previously this was the last part of the function, and hence
553 // this should be rewritten as a `ret'
555 // Check if the function should return a value
556 if (OldFnRetTy == Type::getVoidTy(Context)) {
557 ReturnInst::Create(Context, 0, TheSwitch); // Return void
558 } else if (OldFnRetTy == TheSwitch->getCondition()->getType()) {
559 // return what we have
560 ReturnInst::Create(Context, TheSwitch->getCondition(), TheSwitch);
562 // Otherwise we must have code extracted an unwind or something, just
563 // return whatever we want.
564 ReturnInst::Create(Context,
565 Constant::getNullValue(OldFnRetTy), TheSwitch);
568 TheSwitch->eraseFromParent();
571 // Only a single destination, change the switch into an unconditional
573 BranchInst::Create(TheSwitch->getSuccessor(1), TheSwitch);
574 TheSwitch->eraseFromParent();
577 BranchInst::Create(TheSwitch->getSuccessor(1), TheSwitch->getSuccessor(2),
579 TheSwitch->eraseFromParent();
582 // Otherwise, make the default destination of the switch instruction be one
583 // of the other successors.
584 TheSwitch->setOperand(0, call);
585 TheSwitch->setSuccessor(0, TheSwitch->getSuccessor(NumExitBlocks));
586 TheSwitch->removeCase(NumExitBlocks); // Remove redundant case
591 void CodeExtractor::moveCodeToFunction(Function *newFunction) {
592 Function *oldFunc = (*BlocksToExtract.begin())->getParent();
593 Function::BasicBlockListType &oldBlocks = oldFunc->getBasicBlockList();
594 Function::BasicBlockListType &newBlocks = newFunction->getBasicBlockList();
596 for (std::set<BasicBlock*>::const_iterator i = BlocksToExtract.begin(),
597 e = BlocksToExtract.end(); i != e; ++i) {
598 // Delete the basic block from the old function, and the list of blocks
599 oldBlocks.remove(*i);
601 // Insert this basic block into the new function
602 newBlocks.push_back(*i);
606 /// ExtractRegion - Removes a loop from a function, replaces it with a call to
607 /// new function. Returns pointer to the new function.
611 /// find inputs and outputs for the region
613 /// for inputs: add to function as args, map input instr* to arg#
614 /// for outputs: add allocas for scalars,
615 /// add to func as args, map output instr* to arg#
617 /// rewrite func to use argument #s instead of instr*
619 /// for each scalar output in the function: at every exit, store intermediate
620 /// computed result back into memory.
622 Function *CodeExtractor::
623 ExtractCodeRegion(const std::vector<BasicBlock*> &code) {
624 if (!isEligible(code))
627 // 1) Find inputs, outputs
628 // 2) Construct new function
629 // * Add allocas for defs, pass as args by reference
630 // * Pass in uses as args
631 // 3) Move code region, add call instr to func
633 BlocksToExtract.insert(code.begin(), code.end());
635 Values inputs, outputs;
637 // Assumption: this is a single-entry code region, and the header is the first
638 // block in the region.
639 BasicBlock *header = code[0];
641 for (unsigned i = 1, e = code.size(); i != e; ++i)
642 for (pred_iterator PI = pred_begin(code[i]), E = pred_end(code[i]);
644 assert(BlocksToExtract.count(*PI) &&
645 "No blocks in this region may have entries from outside the region"
646 " except for the first block!");
648 // If we have to split PHI nodes or the entry block, do so now.
649 severSplitPHINodes(header);
651 // If we have any return instructions in the region, split those blocks so
652 // that the return is not in the region.
655 Function *oldFunction = header->getParent();
657 // This takes place of the original loop
658 BasicBlock *codeReplacer = BasicBlock::Create(header->getContext(),
659 "codeRepl", oldFunction,
662 // The new function needs a root node because other nodes can branch to the
663 // head of the region, but the entry node of a function cannot have preds.
664 BasicBlock *newFuncRoot = BasicBlock::Create(header->getContext(),
666 newFuncRoot->getInstList().push_back(BranchInst::Create(header));
668 // Find inputs to, outputs from the code region.
669 findInputsOutputs(inputs, outputs);
671 // Construct new function based on inputs/outputs & add allocas for all defs.
672 Function *newFunction = constructFunction(inputs, outputs, header,
674 codeReplacer, oldFunction,
675 oldFunction->getParent());
677 emitCallAndSwitchStatement(newFunction, codeReplacer, inputs, outputs);
679 moveCodeToFunction(newFunction);
681 // Loop over all of the PHI nodes in the header block, and change any
682 // references to the old incoming edge to be the new incoming edge.
683 for (BasicBlock::iterator I = header->begin(); isa<PHINode>(I); ++I) {
684 PHINode *PN = cast<PHINode>(I);
685 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
686 if (!BlocksToExtract.count(PN->getIncomingBlock(i)))
687 PN->setIncomingBlock(i, newFuncRoot);
690 // Look at all successors of the codeReplacer block. If any of these blocks
691 // had PHI nodes in them, we need to update the "from" block to be the code
692 // replacer, not the original block in the extracted region.
693 std::vector<BasicBlock*> Succs(succ_begin(codeReplacer),
694 succ_end(codeReplacer));
695 for (unsigned i = 0, e = Succs.size(); i != e; ++i)
696 for (BasicBlock::iterator I = Succs[i]->begin(); isa<PHINode>(I); ++I) {
697 PHINode *PN = cast<PHINode>(I);
698 std::set<BasicBlock*> ProcessedPreds;
699 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
700 if (BlocksToExtract.count(PN->getIncomingBlock(i))) {
701 if (ProcessedPreds.insert(PN->getIncomingBlock(i)).second)
702 PN->setIncomingBlock(i, codeReplacer);
704 // There were multiple entries in the PHI for this block, now there
705 // is only one, so remove the duplicated entries.
706 PN->removeIncomingValue(i, false);
712 //cerr << "NEW FUNCTION: " << *newFunction;
713 // verifyFunction(*newFunction);
715 // cerr << "OLD FUNCTION: " << *oldFunction;
716 // verifyFunction(*oldFunction);
718 DEBUG(if (verifyFunction(*newFunction))
719 llvm_report_error("verifyFunction failed!"));
723 bool CodeExtractor::isEligible(const std::vector<BasicBlock*> &code) {
724 // Deny code region if it contains allocas or vastarts.
725 for (std::vector<BasicBlock*>::const_iterator BB = code.begin(), e=code.end();
727 for (BasicBlock::const_iterator I = (*BB)->begin(), Ie = (*BB)->end();
729 if (isa<AllocaInst>(*I))
731 else if (const CallInst *CI = dyn_cast<CallInst>(I))
732 if (const Function *F = CI->getCalledFunction())
733 if (F->getIntrinsicID() == Intrinsic::vastart)
739 /// ExtractCodeRegion - slurp a sequence of basic blocks into a brand new
742 Function* llvm::ExtractCodeRegion(DominatorTree &DT,
743 const std::vector<BasicBlock*> &code,
744 bool AggregateArgs) {
745 return CodeExtractor(&DT, AggregateArgs).ExtractCodeRegion(code);
748 /// ExtractBasicBlock - slurp a natural loop into a brand new function
750 Function* llvm::ExtractLoop(DominatorTree &DT, Loop *L, bool AggregateArgs) {
751 return CodeExtractor(&DT, AggregateArgs).ExtractCodeRegion(L->getBlocks());
754 /// ExtractBasicBlock - slurp a basic block into a brand new function
756 Function* llvm::ExtractBasicBlock(BasicBlock *BB, bool AggregateArgs) {
757 std::vector<BasicBlock*> Blocks;
758 Blocks.push_back(BB);
759 return CodeExtractor(0, AggregateArgs).ExtractCodeRegion(Blocks);