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/CodeExtractor.h"
17 #include "llvm/ADT/STLExtras.h"
18 #include "llvm/ADT/SetVector.h"
19 #include "llvm/ADT/StringExtras.h"
20 #include "llvm/Analysis/LoopInfo.h"
21 #include "llvm/Analysis/RegionInfo.h"
22 #include "llvm/Analysis/RegionIterator.h"
23 #include "llvm/IR/Constants.h"
24 #include "llvm/IR/DerivedTypes.h"
25 #include "llvm/IR/Dominators.h"
26 #include "llvm/IR/Instructions.h"
27 #include "llvm/IR/Intrinsics.h"
28 #include "llvm/IR/LLVMContext.h"
29 #include "llvm/IR/Module.h"
30 #include "llvm/IR/Verifier.h"
31 #include "llvm/Pass.h"
32 #include "llvm/Support/CommandLine.h"
33 #include "llvm/Support/Debug.h"
34 #include "llvm/Support/ErrorHandling.h"
35 #include "llvm/Support/raw_ostream.h"
36 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
41 #define DEBUG_TYPE "code-extractor"
43 // Provide a command-line option to aggregate function arguments into a struct
44 // for functions produced by the code extractor. This is useful when converting
45 // extracted functions to pthread-based code, as only one argument (void*) can
46 // be passed in to pthread_create().
48 AggregateArgsOpt("aggregate-extracted-args", cl::Hidden,
49 cl::desc("Aggregate arguments to code-extracted functions"));
51 /// \brief Test whether a block is valid for extraction.
52 static bool isBlockValidForExtraction(const BasicBlock &BB) {
53 // Landing pads must be in the function where they were inserted for cleanup.
57 // Don't hoist code containing allocas, invokes, or vastarts.
58 for (BasicBlock::const_iterator I = BB.begin(), E = BB.end(); I != E; ++I) {
59 if (isa<AllocaInst>(I) || isa<InvokeInst>(I))
61 if (const CallInst *CI = dyn_cast<CallInst>(I))
62 if (const Function *F = CI->getCalledFunction())
63 if (F->getIntrinsicID() == Intrinsic::vastart)
70 /// \brief Build a set of blocks to extract if the input blocks are viable.
71 template <typename IteratorT>
72 static SetVector<BasicBlock *> buildExtractionBlockSet(IteratorT BBBegin,
74 SetVector<BasicBlock *> Result;
76 assert(BBBegin != BBEnd);
78 // Loop over the blocks, adding them to our set-vector, and aborting with an
79 // empty set if we encounter invalid blocks.
81 if (!Result.insert(*BBBegin))
82 llvm_unreachable("Repeated basic blocks in extraction input");
84 if (!isBlockValidForExtraction(**BBBegin)) {
88 } while (++BBBegin != BBEnd);
91 for (SetVector<BasicBlock *>::iterator I = std::next(Result.begin()),
94 for (pred_iterator PI = pred_begin(*I), PE = pred_end(*I);
96 assert(Result.count(*PI) &&
97 "No blocks in this region may have entries from outside the region"
98 " except for the first block!");
104 /// \brief Helper to call buildExtractionBlockSet with an ArrayRef.
105 static SetVector<BasicBlock *>
106 buildExtractionBlockSet(ArrayRef<BasicBlock *> BBs) {
107 return buildExtractionBlockSet(BBs.begin(), BBs.end());
110 /// \brief Helper to call buildExtractionBlockSet with a RegionNode.
111 static SetVector<BasicBlock *>
112 buildExtractionBlockSet(const RegionNode &RN) {
113 if (!RN.isSubRegion())
114 // Just a single BasicBlock.
115 return buildExtractionBlockSet(RN.getNodeAs<BasicBlock>());
117 const Region &R = *RN.getNodeAs<Region>();
119 return buildExtractionBlockSet(R.block_begin(), R.block_end());
122 CodeExtractor::CodeExtractor(BasicBlock *BB, bool AggregateArgs)
123 : DT(nullptr), AggregateArgs(AggregateArgs||AggregateArgsOpt),
124 Blocks(buildExtractionBlockSet(BB)), NumExitBlocks(~0U) {}
126 CodeExtractor::CodeExtractor(ArrayRef<BasicBlock *> BBs, DominatorTree *DT,
128 : DT(DT), AggregateArgs(AggregateArgs||AggregateArgsOpt),
129 Blocks(buildExtractionBlockSet(BBs)), NumExitBlocks(~0U) {}
131 CodeExtractor::CodeExtractor(DominatorTree &DT, Loop &L, bool AggregateArgs)
132 : DT(&DT), AggregateArgs(AggregateArgs||AggregateArgsOpt),
133 Blocks(buildExtractionBlockSet(L.getBlocks())), NumExitBlocks(~0U) {}
135 CodeExtractor::CodeExtractor(DominatorTree &DT, const RegionNode &RN,
137 : DT(&DT), AggregateArgs(AggregateArgs||AggregateArgsOpt),
138 Blocks(buildExtractionBlockSet(RN)), NumExitBlocks(~0U) {}
140 /// definedInRegion - Return true if the specified value is defined in the
141 /// extracted region.
142 static bool definedInRegion(const SetVector<BasicBlock *> &Blocks, Value *V) {
143 if (Instruction *I = dyn_cast<Instruction>(V))
144 if (Blocks.count(I->getParent()))
149 /// definedInCaller - Return true if the specified value is defined in the
150 /// function being code extracted, but not in the region being extracted.
151 /// These values must be passed in as live-ins to the function.
152 static bool definedInCaller(const SetVector<BasicBlock *> &Blocks, Value *V) {
153 if (isa<Argument>(V)) return true;
154 if (Instruction *I = dyn_cast<Instruction>(V))
155 if (!Blocks.count(I->getParent()))
160 void CodeExtractor::findInputsOutputs(ValueSet &Inputs,
161 ValueSet &Outputs) const {
162 for (BasicBlock *BB : Blocks) {
163 // If a used value is defined outside the region, it's an input. If an
164 // instruction is used outside the region, it's an output.
165 for (Instruction &II : *BB) {
166 for (User::op_iterator OI = II.op_begin(), OE = II.op_end(); OI != OE;
168 if (definedInCaller(Blocks, *OI))
171 for (User *U : II.users())
172 if (!definedInRegion(Blocks, U)) {
180 /// severSplitPHINodes - If a PHI node has multiple inputs from outside of the
181 /// region, we need to split the entry block of the region so that the PHI node
182 /// is easier to deal with.
183 void CodeExtractor::severSplitPHINodes(BasicBlock *&Header) {
184 unsigned NumPredsFromRegion = 0;
185 unsigned NumPredsOutsideRegion = 0;
187 if (Header != &Header->getParent()->getEntryBlock()) {
188 PHINode *PN = dyn_cast<PHINode>(Header->begin());
189 if (!PN) return; // No PHI nodes.
191 // If the header node contains any PHI nodes, check to see if there is more
192 // than one entry from outside the region. If so, we need to sever the
193 // header block into two.
194 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
195 if (Blocks.count(PN->getIncomingBlock(i)))
196 ++NumPredsFromRegion;
198 ++NumPredsOutsideRegion;
200 // If there is one (or fewer) predecessor from outside the region, we don't
201 // need to do anything special.
202 if (NumPredsOutsideRegion <= 1) return;
205 // Otherwise, we need to split the header block into two pieces: one
206 // containing PHI nodes merging values from outside of the region, and a
207 // second that contains all of the code for the block and merges back any
208 // incoming values from inside of the region.
209 BasicBlock::iterator AfterPHIs = Header->getFirstNonPHI()->getIterator();
210 BasicBlock *NewBB = Header->splitBasicBlock(AfterPHIs,
211 Header->getName()+".ce");
213 // We only want to code extract the second block now, and it becomes the new
214 // header of the region.
215 BasicBlock *OldPred = Header;
216 Blocks.remove(OldPred);
217 Blocks.insert(NewBB);
220 // Okay, update dominator sets. The blocks that dominate the new one are the
221 // blocks that dominate TIBB plus the new block itself.
223 DT->splitBlock(NewBB);
225 // Okay, now we need to adjust the PHI nodes and any branches from within the
226 // region to go to the new header block instead of the old header block.
227 if (NumPredsFromRegion) {
228 PHINode *PN = cast<PHINode>(OldPred->begin());
229 // Loop over all of the predecessors of OldPred that are in the region,
230 // changing them to branch to NewBB instead.
231 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
232 if (Blocks.count(PN->getIncomingBlock(i))) {
233 TerminatorInst *TI = PN->getIncomingBlock(i)->getTerminator();
234 TI->replaceUsesOfWith(OldPred, NewBB);
237 // Okay, everything within the region is now branching to the right block, we
238 // just have to update the PHI nodes now, inserting PHI nodes into NewBB.
239 for (AfterPHIs = OldPred->begin(); isa<PHINode>(AfterPHIs); ++AfterPHIs) {
240 PHINode *PN = cast<PHINode>(AfterPHIs);
241 // Create a new PHI node in the new region, which has an incoming value
242 // from OldPred of PN.
243 PHINode *NewPN = PHINode::Create(PN->getType(), 1 + NumPredsFromRegion,
244 PN->getName() + ".ce", &NewBB->front());
245 NewPN->addIncoming(PN, OldPred);
247 // Loop over all of the incoming value in PN, moving them to NewPN if they
248 // are from the extracted region.
249 for (unsigned i = 0; i != PN->getNumIncomingValues(); ++i) {
250 if (Blocks.count(PN->getIncomingBlock(i))) {
251 NewPN->addIncoming(PN->getIncomingValue(i), PN->getIncomingBlock(i));
252 PN->removeIncomingValue(i);
260 void CodeExtractor::splitReturnBlocks() {
261 for (BasicBlock *Block : Blocks)
262 if (ReturnInst *RI = dyn_cast<ReturnInst>(Block->getTerminator())) {
264 Block->splitBasicBlock(RI->getIterator(), Block->getName() + ".ret");
266 // Old dominates New. New node dominates all other nodes dominated
268 DomTreeNode *OldNode = DT->getNode(Block);
269 SmallVector<DomTreeNode *, 8> Children(OldNode->begin(),
272 DomTreeNode *NewNode = DT->addNewBlock(New, Block);
274 for (DomTreeNode *I : Children)
275 DT->changeImmediateDominator(I, NewNode);
280 /// constructFunction - make a function based on inputs and outputs, as follows:
281 /// f(in0, ..., inN, out0, ..., outN)
283 Function *CodeExtractor::constructFunction(const ValueSet &inputs,
284 const ValueSet &outputs,
286 BasicBlock *newRootNode,
287 BasicBlock *newHeader,
288 Function *oldFunction,
290 DEBUG(dbgs() << "inputs: " << inputs.size() << "\n");
291 DEBUG(dbgs() << "outputs: " << outputs.size() << "\n");
293 // This function returns unsigned, outputs will go back by reference.
294 switch (NumExitBlocks) {
296 case 1: RetTy = Type::getVoidTy(header->getContext()); break;
297 case 2: RetTy = Type::getInt1Ty(header->getContext()); break;
298 default: RetTy = Type::getInt16Ty(header->getContext()); break;
301 std::vector<Type*> paramTy;
303 // Add the types of the input values to the function's argument list
304 for (Value *value : inputs) {
305 DEBUG(dbgs() << "value used in func: " << *value << "\n");
306 paramTy.push_back(value->getType());
309 // Add the types of the output values to the function's argument list.
310 for (Value *output : outputs) {
311 DEBUG(dbgs() << "instr used in func: " << *output << "\n");
313 paramTy.push_back(output->getType());
315 paramTy.push_back(PointerType::getUnqual(output->getType()));
319 dbgs() << "Function type: " << *RetTy << " f(";
320 for (Type *i : paramTy)
321 dbgs() << *i << ", ";
325 StructType *StructTy;
326 if (AggregateArgs && (inputs.size() + outputs.size() > 0)) {
327 StructTy = StructType::get(M->getContext(), paramTy);
329 paramTy.push_back(PointerType::getUnqual(StructTy));
331 FunctionType *funcType =
332 FunctionType::get(RetTy, paramTy, false);
334 // Create the new function
335 Function *newFunction = Function::Create(funcType,
336 GlobalValue::InternalLinkage,
337 oldFunction->getName() + "_" +
338 header->getName(), M);
339 // If the old function is no-throw, so is the new one.
340 if (oldFunction->doesNotThrow())
341 newFunction->setDoesNotThrow();
343 newFunction->getBasicBlockList().push_back(newRootNode);
345 // Create an iterator to name all of the arguments we inserted.
346 Function::arg_iterator AI = newFunction->arg_begin();
348 // Rewrite all users of the inputs in the extracted region to use the
349 // arguments (or appropriate addressing into struct) instead.
350 for (unsigned i = 0, e = inputs.size(); i != e; ++i) {
354 Idx[0] = Constant::getNullValue(Type::getInt32Ty(header->getContext()));
355 Idx[1] = ConstantInt::get(Type::getInt32Ty(header->getContext()), i);
356 TerminatorInst *TI = newFunction->begin()->getTerminator();
357 GetElementPtrInst *GEP = GetElementPtrInst::Create(
358 StructTy, &*AI, Idx, "gep_" + inputs[i]->getName(), TI);
359 RewriteVal = new LoadInst(GEP, "loadgep_" + inputs[i]->getName(), TI);
363 std::vector<User*> Users(inputs[i]->user_begin(), inputs[i]->user_end());
364 for (User *use : Users)
365 if (Instruction *inst = dyn_cast<Instruction>(use))
366 if (Blocks.count(inst->getParent()))
367 inst->replaceUsesOfWith(inputs[i], RewriteVal);
370 // Set names for input and output arguments.
371 if (!AggregateArgs) {
372 AI = newFunction->arg_begin();
373 for (unsigned i = 0, e = inputs.size(); i != e; ++i, ++AI)
374 AI->setName(inputs[i]->getName());
375 for (unsigned i = 0, e = outputs.size(); i != e; ++i, ++AI)
376 AI->setName(outputs[i]->getName()+".out");
379 // Rewrite branches to basic blocks outside of the loop to new dummy blocks
380 // within the new function. This must be done before we lose track of which
381 // blocks were originally in the code region.
382 std::vector<User*> Users(header->user_begin(), header->user_end());
383 for (unsigned i = 0, e = Users.size(); i != e; ++i)
384 // The BasicBlock which contains the branch is not in the region
385 // modify the branch target to a new block
386 if (TerminatorInst *TI = dyn_cast<TerminatorInst>(Users[i]))
387 if (!Blocks.count(TI->getParent()) &&
388 TI->getParent()->getParent() == oldFunction)
389 TI->replaceUsesOfWith(header, newHeader);
394 /// FindPhiPredForUseInBlock - Given a value and a basic block, find a PHI
395 /// that uses the value within the basic block, and return the predecessor
396 /// block associated with that use, or return 0 if none is found.
397 static BasicBlock* FindPhiPredForUseInBlock(Value* Used, BasicBlock* BB) {
398 for (Use &U : Used->uses()) {
399 PHINode *P = dyn_cast<PHINode>(U.getUser());
400 if (P && P->getParent() == BB)
401 return P->getIncomingBlock(U);
407 /// emitCallAndSwitchStatement - This method sets up the caller side by adding
408 /// the call instruction, splitting any PHI nodes in the header block as
411 emitCallAndSwitchStatement(Function *newFunction, BasicBlock *codeReplacer,
412 ValueSet &inputs, ValueSet &outputs) {
413 // Emit a call to the new function, passing in: *pointer to struct (if
414 // aggregating parameters), or plan inputs and allocated memory for outputs
415 std::vector<Value*> params, StructValues, ReloadOutputs, Reloads;
417 LLVMContext &Context = newFunction->getContext();
419 // Add inputs as params, or to be filled into the struct
420 for (Value *input : inputs)
422 StructValues.push_back(input);
424 params.push_back(input);
426 // Create allocas for the outputs
427 for (Value *output : outputs) {
429 StructValues.push_back(output);
432 new AllocaInst(output->getType(), nullptr, output->getName() + ".loc",
433 &codeReplacer->getParent()->front().front());
434 ReloadOutputs.push_back(alloca);
435 params.push_back(alloca);
439 StructType *StructArgTy = nullptr;
440 AllocaInst *Struct = nullptr;
441 if (AggregateArgs && (inputs.size() + outputs.size() > 0)) {
442 std::vector<Type*> ArgTypes;
443 for (ValueSet::iterator v = StructValues.begin(),
444 ve = StructValues.end(); v != ve; ++v)
445 ArgTypes.push_back((*v)->getType());
447 // Allocate a struct at the beginning of this function
448 StructArgTy = StructType::get(newFunction->getContext(), ArgTypes);
449 Struct = new AllocaInst(StructArgTy, nullptr, "structArg",
450 &codeReplacer->getParent()->front().front());
451 params.push_back(Struct);
453 for (unsigned i = 0, e = inputs.size(); i != e; ++i) {
455 Idx[0] = Constant::getNullValue(Type::getInt32Ty(Context));
456 Idx[1] = ConstantInt::get(Type::getInt32Ty(Context), i);
457 GetElementPtrInst *GEP = GetElementPtrInst::Create(
458 StructArgTy, Struct, Idx, "gep_" + StructValues[i]->getName());
459 codeReplacer->getInstList().push_back(GEP);
460 StoreInst *SI = new StoreInst(StructValues[i], GEP);
461 codeReplacer->getInstList().push_back(SI);
465 // Emit the call to the function
466 CallInst *call = CallInst::Create(newFunction, params,
467 NumExitBlocks > 1 ? "targetBlock" : "");
468 codeReplacer->getInstList().push_back(call);
470 Function::arg_iterator OutputArgBegin = newFunction->arg_begin();
471 unsigned FirstOut = inputs.size();
473 std::advance(OutputArgBegin, inputs.size());
475 // Reload the outputs passed in by reference
476 for (unsigned i = 0, e = outputs.size(); i != e; ++i) {
477 Value *Output = nullptr;
480 Idx[0] = Constant::getNullValue(Type::getInt32Ty(Context));
481 Idx[1] = ConstantInt::get(Type::getInt32Ty(Context), FirstOut + i);
482 GetElementPtrInst *GEP = GetElementPtrInst::Create(
483 StructArgTy, Struct, Idx, "gep_reload_" + outputs[i]->getName());
484 codeReplacer->getInstList().push_back(GEP);
487 Output = ReloadOutputs[i];
489 LoadInst *load = new LoadInst(Output, outputs[i]->getName()+".reload");
490 Reloads.push_back(load);
491 codeReplacer->getInstList().push_back(load);
492 std::vector<User*> Users(outputs[i]->user_begin(), outputs[i]->user_end());
493 for (unsigned u = 0, e = Users.size(); u != e; ++u) {
494 Instruction *inst = cast<Instruction>(Users[u]);
495 if (!Blocks.count(inst->getParent()))
496 inst->replaceUsesOfWith(outputs[i], load);
500 // Now we can emit a switch statement using the call as a value.
501 SwitchInst *TheSwitch =
502 SwitchInst::Create(Constant::getNullValue(Type::getInt16Ty(Context)),
503 codeReplacer, 0, codeReplacer);
505 // Since there may be multiple exits from the original region, make the new
506 // function return an unsigned, switch on that number. This loop iterates
507 // over all of the blocks in the extracted region, updating any terminator
508 // instructions in the to-be-extracted region that branch to blocks that are
509 // not in the region to be extracted.
510 std::map<BasicBlock*, BasicBlock*> ExitBlockMap;
512 unsigned switchVal = 0;
513 for (BasicBlock *Block : Blocks) {
514 TerminatorInst *TI = Block->getTerminator();
515 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
516 if (!Blocks.count(TI->getSuccessor(i))) {
517 BasicBlock *OldTarget = TI->getSuccessor(i);
518 // add a new basic block which returns the appropriate value
519 BasicBlock *&NewTarget = ExitBlockMap[OldTarget];
521 // If we don't already have an exit stub for this non-extracted
522 // destination, create one now!
523 NewTarget = BasicBlock::Create(Context,
524 OldTarget->getName() + ".exitStub",
526 unsigned SuccNum = switchVal++;
528 Value *brVal = nullptr;
529 switch (NumExitBlocks) {
531 case 1: break; // No value needed.
532 case 2: // Conditional branch, return a bool
533 brVal = ConstantInt::get(Type::getInt1Ty(Context), !SuccNum);
536 brVal = ConstantInt::get(Type::getInt16Ty(Context), SuccNum);
540 ReturnInst *NTRet = ReturnInst::Create(Context, brVal, NewTarget);
542 // Update the switch instruction.
543 TheSwitch->addCase(ConstantInt::get(Type::getInt16Ty(Context),
547 // Restore values just before we exit
548 Function::arg_iterator OAI = OutputArgBegin;
549 for (unsigned out = 0, e = outputs.size(); out != e; ++out) {
550 // For an invoke, the normal destination is the only one that is
551 // dominated by the result of the invocation
552 BasicBlock *DefBlock = cast<Instruction>(outputs[out])->getParent();
554 bool DominatesDef = true;
556 BasicBlock *NormalDest = nullptr;
557 if (auto *Invoke = dyn_cast<InvokeInst>(outputs[out]))
558 NormalDest = Invoke->getNormalDest();
561 DefBlock = NormalDest;
563 // Make sure we are looking at the original successor block, not
564 // at a newly inserted exit block, which won't be in the dominator
566 for (const auto &I : ExitBlockMap)
567 if (DefBlock == I.second) {
572 // In the extract block case, if the block we are extracting ends
573 // with an invoke instruction, make sure that we don't emit a
574 // store of the invoke value for the unwind block.
575 if (!DT && DefBlock != OldTarget)
576 DominatesDef = false;
580 DominatesDef = DT->dominates(DefBlock, OldTarget);
582 // If the output value is used by a phi in the target block,
583 // then we need to test for dominance of the phi's predecessor
584 // instead. Unfortunately, this a little complicated since we
585 // have already rewritten uses of the value to uses of the reload.
586 BasicBlock* pred = FindPhiPredForUseInBlock(Reloads[out],
588 if (pred && DT && DT->dominates(DefBlock, pred))
595 Idx[0] = Constant::getNullValue(Type::getInt32Ty(Context));
596 Idx[1] = ConstantInt::get(Type::getInt32Ty(Context),
598 GetElementPtrInst *GEP = GetElementPtrInst::Create(
599 StructArgTy, &*OAI, Idx, "gep_" + outputs[out]->getName(),
601 new StoreInst(outputs[out], GEP, NTRet);
603 new StoreInst(outputs[out], &*OAI, NTRet);
606 // Advance output iterator even if we don't emit a store
607 if (!AggregateArgs) ++OAI;
611 // rewrite the original branch instruction with this new target
612 TI->setSuccessor(i, NewTarget);
616 // Now that we've done the deed, simplify the switch instruction.
617 Type *OldFnRetTy = TheSwitch->getParent()->getParent()->getReturnType();
618 switch (NumExitBlocks) {
620 // There are no successors (the block containing the switch itself), which
621 // means that previously this was the last part of the function, and hence
622 // this should be rewritten as a `ret'
624 // Check if the function should return a value
625 if (OldFnRetTy->isVoidTy()) {
626 ReturnInst::Create(Context, nullptr, TheSwitch); // Return void
627 } else if (OldFnRetTy == TheSwitch->getCondition()->getType()) {
628 // return what we have
629 ReturnInst::Create(Context, TheSwitch->getCondition(), TheSwitch);
631 // Otherwise we must have code extracted an unwind or something, just
632 // return whatever we want.
633 ReturnInst::Create(Context,
634 Constant::getNullValue(OldFnRetTy), TheSwitch);
637 TheSwitch->eraseFromParent();
640 // Only a single destination, change the switch into an unconditional
642 BranchInst::Create(TheSwitch->getSuccessor(1), TheSwitch);
643 TheSwitch->eraseFromParent();
646 BranchInst::Create(TheSwitch->getSuccessor(1), TheSwitch->getSuccessor(2),
648 TheSwitch->eraseFromParent();
651 // Otherwise, make the default destination of the switch instruction be one
652 // of the other successors.
653 TheSwitch->setCondition(call);
654 TheSwitch->setDefaultDest(TheSwitch->getSuccessor(NumExitBlocks));
655 // Remove redundant case
656 TheSwitch->removeCase(SwitchInst::CaseIt(TheSwitch, NumExitBlocks-1));
661 void CodeExtractor::moveCodeToFunction(Function *newFunction) {
662 Function *oldFunc = (*Blocks.begin())->getParent();
663 Function::BasicBlockListType &oldBlocks = oldFunc->getBasicBlockList();
664 Function::BasicBlockListType &newBlocks = newFunction->getBasicBlockList();
666 for (BasicBlock *Block : Blocks) {
667 // Delete the basic block from the old function, and the list of blocks
668 oldBlocks.remove(Block);
670 // Insert this basic block into the new function
671 newBlocks.push_back(Block);
675 Function *CodeExtractor::extractCodeRegion() {
679 ValueSet inputs, outputs;
681 // Assumption: this is a single-entry code region, and the header is the first
682 // block in the region.
683 BasicBlock *header = *Blocks.begin();
685 // If we have to split PHI nodes or the entry block, do so now.
686 severSplitPHINodes(header);
688 // If we have any return instructions in the region, split those blocks so
689 // that the return is not in the region.
692 Function *oldFunction = header->getParent();
694 // This takes place of the original loop
695 BasicBlock *codeReplacer = BasicBlock::Create(header->getContext(),
696 "codeRepl", oldFunction,
699 // The new function needs a root node because other nodes can branch to the
700 // head of the region, but the entry node of a function cannot have preds.
701 BasicBlock *newFuncRoot = BasicBlock::Create(header->getContext(),
703 newFuncRoot->getInstList().push_back(BranchInst::Create(header));
705 // Find inputs to, outputs from the code region.
706 findInputsOutputs(inputs, outputs);
708 SmallPtrSet<BasicBlock *, 1> ExitBlocks;
709 for (BasicBlock *Block : Blocks)
710 for (succ_iterator SI = succ_begin(Block), SE = succ_end(Block); SI != SE;
712 if (!Blocks.count(*SI))
713 ExitBlocks.insert(*SI);
714 NumExitBlocks = ExitBlocks.size();
716 // Construct new function based on inputs/outputs & add allocas for all defs.
717 Function *newFunction = constructFunction(inputs, outputs, header,
719 codeReplacer, oldFunction,
720 oldFunction->getParent());
722 emitCallAndSwitchStatement(newFunction, codeReplacer, inputs, outputs);
724 moveCodeToFunction(newFunction);
726 // Loop over all of the PHI nodes in the header block, and change any
727 // references to the old incoming edge to be the new incoming edge.
728 for (BasicBlock::iterator I = header->begin(); isa<PHINode>(I); ++I) {
729 PHINode *PN = cast<PHINode>(I);
730 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
731 if (!Blocks.count(PN->getIncomingBlock(i)))
732 PN->setIncomingBlock(i, newFuncRoot);
735 // Look at all successors of the codeReplacer block. If any of these blocks
736 // had PHI nodes in them, we need to update the "from" block to be the code
737 // replacer, not the original block in the extracted region.
738 std::vector<BasicBlock*> Succs(succ_begin(codeReplacer),
739 succ_end(codeReplacer));
740 for (unsigned i = 0, e = Succs.size(); i != e; ++i)
741 for (BasicBlock::iterator I = Succs[i]->begin(); isa<PHINode>(I); ++I) {
742 PHINode *PN = cast<PHINode>(I);
743 std::set<BasicBlock*> ProcessedPreds;
744 for (unsigned i = 0, e = PN->getNumIncomingValues(); i != e; ++i)
745 if (Blocks.count(PN->getIncomingBlock(i))) {
746 if (ProcessedPreds.insert(PN->getIncomingBlock(i)).second)
747 PN->setIncomingBlock(i, codeReplacer);
749 // There were multiple entries in the PHI for this block, now there
750 // is only one, so remove the duplicated entries.
751 PN->removeIncomingValue(i, false);
757 //cerr << "NEW FUNCTION: " << *newFunction;
758 // verifyFunction(*newFunction);
760 // cerr << "OLD FUNCTION: " << *oldFunction;
761 // verifyFunction(*oldFunction);
763 DEBUG(if (verifyFunction(*newFunction))
764 report_fatal_error("verifyFunction failed!"));