1 //===- PromoteMemoryToRegister.cpp - Convert allocas to registers ---------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file promote memory references to be register references. It promotes
11 // alloca instructions which only have loads and stores as uses. An alloca is
12 // transformed by using dominator frontiers to place PHI nodes, then traversing
13 // the function in depth-first order to rewrite loads and stores as appropriate.
14 // This is just the standard SSA construction algorithm to construct "pruned"
17 //===----------------------------------------------------------------------===//
19 #include "llvm/Transforms/Utils/PromoteMemToReg.h"
20 #include "llvm/Constants.h"
21 #include "llvm/DerivedTypes.h"
22 #include "llvm/Function.h"
23 #include "llvm/Instructions.h"
24 #include "llvm/Analysis/Dominators.h"
25 #include "llvm/Analysis/AliasSetTracker.h"
26 #include "llvm/ADT/StringExtras.h"
27 #include "llvm/Transforms/Utils/Local.h"
28 #include "llvm/Support/CFG.h"
29 #include "llvm/Support/StableBasicBlockNumbering.h"
33 /// isAllocaPromotable - Return true if this alloca is legal for promotion.
34 /// This is true if there are only loads and stores to the alloca.
36 bool llvm::isAllocaPromotable(const AllocaInst *AI, const TargetData &TD) {
37 // FIXME: If the memory unit is of pointer or integer type, we can permit
38 // assignments to subsections of the memory unit.
40 // Only allow direct loads and stores...
41 for (Value::use_const_iterator UI = AI->use_begin(), UE = AI->use_end();
42 UI != UE; ++UI) // Loop over all of the uses of the alloca
43 if (isa<LoadInst>(*UI)) {
45 } else if (const StoreInst *SI = dyn_cast<StoreInst>(*UI)) {
46 if (SI->getOperand(0) == AI)
47 return false; // Don't allow a store OF the AI, only INTO the AI.
49 return false; // Not a load or store.
56 struct PromoteMem2Reg {
57 /// Allocas - The alloca instructions being promoted.
59 std::vector<AllocaInst*> Allocas;
61 DominanceFrontier &DF;
64 /// AST - An AliasSetTracker object to update. If null, don't update it.
68 /// AllocaLookup - Reverse mapping of Allocas.
70 std::map<AllocaInst*, unsigned> AllocaLookup;
72 /// NewPhiNodes - The PhiNodes we're adding.
74 std::map<BasicBlock*, std::vector<PHINode*> > NewPhiNodes;
76 /// PointerAllocaValues - If we are updating an AliasSetTracker, then for
77 /// each alloca that is of pointer type, we keep track of what to copyValue
78 /// to the inserted PHI nodes here.
80 std::vector<Value*> PointerAllocaValues;
82 /// Visited - The set of basic blocks the renamer has already visited.
84 std::set<BasicBlock*> Visited;
86 /// BBNumbers - Contains a stable numbering of basic blocks to avoid
87 /// non-determinstic behavior.
88 StableBasicBlockNumbering BBNumbers;
91 PromoteMem2Reg(const std::vector<AllocaInst*> &A, DominatorTree &dt,
92 DominanceFrontier &df, const TargetData &td,
94 : Allocas(A), DT(dt), DF(df), TD(td), AST(ast) {}
98 /// dominates - Return true if I1 dominates I2 using the DominatorTree.
100 bool dominates(Instruction *I1, Instruction *I2) const {
101 if (InvokeInst *II = dyn_cast<InvokeInst>(I1))
102 I1 = II->getNormalDest()->begin();
103 return DT[I1->getParent()]->dominates(DT[I2->getParent()]);
107 void MarkDominatingPHILive(BasicBlock *BB, unsigned AllocaNum,
108 std::set<PHINode*> &DeadPHINodes);
109 void PromoteLocallyUsedAlloca(BasicBlock *BB, AllocaInst *AI);
110 void PromoteLocallyUsedAllocas(BasicBlock *BB,
111 const std::vector<AllocaInst*> &AIs);
113 void RenamePass(BasicBlock *BB, BasicBlock *Pred,
114 std::vector<Value*> &IncVals);
115 bool QueuePhiNode(BasicBlock *BB, unsigned AllocaIdx, unsigned &Version,
116 std::set<PHINode*> &InsertedPHINodes);
118 } // end of anonymous namespace
120 void PromoteMem2Reg::run() {
121 Function &F = *DF.getRoot()->getParent();
123 // LocallyUsedAllocas - Keep track of all of the alloca instructions which are
124 // only used in a single basic block. These instructions can be efficiently
125 // promoted by performing a single linear scan over that one block. Since
126 // individual basic blocks are sometimes large, we group together all allocas
127 // that are live in a single basic block by the basic block they are live in.
128 std::map<BasicBlock*, std::vector<AllocaInst*> > LocallyUsedAllocas;
130 if (AST) PointerAllocaValues.resize(Allocas.size());
132 for (unsigned AllocaNum = 0; AllocaNum != Allocas.size(); ++AllocaNum) {
133 AllocaInst *AI = Allocas[AllocaNum];
135 assert(isAllocaPromotable(AI, TD) &&
136 "Cannot promote non-promotable alloca!");
137 assert(AI->getParent()->getParent() == &F &&
138 "All allocas should be in the same function, which is same as DF!");
140 if (AI->use_empty()) {
141 // If there are no uses of the alloca, just delete it now.
142 if (AST) AST->deleteValue(AI);
143 AI->getParent()->getInstList().erase(AI);
145 // Remove the alloca from the Allocas list, since it has been processed
146 Allocas[AllocaNum] = Allocas.back();
152 // Calculate the set of read and write-locations for each alloca. This is
153 // analogous to finding the 'uses' and 'definitions' of each variable.
154 std::vector<BasicBlock*> DefiningBlocks;
155 std::vector<BasicBlock*> UsingBlocks;
157 BasicBlock *OnlyBlock = 0;
158 bool OnlyUsedInOneBlock = true;
160 // As we scan the uses of the alloca instruction, keep track of stores, and
161 // decide whether all of the loads and stores to the alloca are within the
163 Value *AllocaPointerVal = 0;
164 for (Value::use_iterator U =AI->use_begin(), E = AI->use_end(); U != E;++U){
165 Instruction *User = cast<Instruction>(*U);
166 if (StoreInst *SI = dyn_cast<StoreInst>(User)) {
167 // Remember the basic blocks which define new values for the alloca
168 DefiningBlocks.push_back(SI->getParent());
169 AllocaPointerVal = SI->getOperand(0);
170 } else if (LoadInst *LI = dyn_cast<LoadInst>(User)) {
171 // Otherwise it must be a load instruction, keep track of variable reads
172 UsingBlocks.push_back(LI->getParent());
173 AllocaPointerVal = LI;
176 if (OnlyUsedInOneBlock) {
178 OnlyBlock = User->getParent();
179 else if (OnlyBlock != User->getParent())
180 OnlyUsedInOneBlock = false;
184 // If the alloca is only read and written in one basic block, just perform a
185 // linear sweep over the block to eliminate it.
186 if (OnlyUsedInOneBlock) {
187 LocallyUsedAllocas[OnlyBlock].push_back(AI);
189 // Remove the alloca from the Allocas list, since it will be processed.
190 Allocas[AllocaNum] = Allocas.back();
197 PointerAllocaValues[AllocaNum] = AllocaPointerVal;
199 // If we haven't computed a numbering for the BB's in the function, do so
201 BBNumbers.compute(F);
203 // Compute the locations where PhiNodes need to be inserted. Look at the
204 // dominance frontier of EACH basic-block we have a write in.
206 unsigned CurrentVersion = 0;
207 std::set<PHINode*> InsertedPHINodes;
208 std::vector<unsigned> DFBlocks;
209 while (!DefiningBlocks.empty()) {
210 BasicBlock *BB = DefiningBlocks.back();
211 DefiningBlocks.pop_back();
213 // Look up the DF for this write, add it to PhiNodes
214 DominanceFrontier::const_iterator it = DF.find(BB);
215 if (it != DF.end()) {
216 const DominanceFrontier::DomSetType &S = it->second;
218 // In theory we don't need the indirection through the DFBlocks vector.
219 // In practice, the order of calling QueuePhiNode would depend on the
220 // (unspecified) ordering of basic blocks in the dominance frontier,
221 // which would give PHI nodes non-determinstic subscripts. Fix this by
222 // processing blocks in order of the occurance in the function.
223 for (DominanceFrontier::DomSetType::const_iterator P = S.begin(),
224 PE = S.end(); P != PE; ++P)
225 DFBlocks.push_back(BBNumbers.getNumber(*P));
227 // Sort by which the block ordering in the function.
228 std::sort(DFBlocks.begin(), DFBlocks.end());
230 for (unsigned i = 0, e = DFBlocks.size(); i != e; ++i) {
231 BasicBlock *BB = BBNumbers.getBlock(DFBlocks[i]);
232 if (QueuePhiNode(BB, AllocaNum, CurrentVersion, InsertedPHINodes))
233 DefiningBlocks.push_back(BB);
239 // Now that we have inserted PHI nodes along the Iterated Dominance Frontier
240 // of the writes to the variable, scan through the reads of the variable,
241 // marking PHI nodes which are actually necessary as alive (by removing them
242 // from the InsertedPHINodes set). This is not perfect: there may PHI
243 // marked alive because of loads which are dominated by stores, but there
244 // will be no unmarked PHI nodes which are actually used.
246 for (unsigned i = 0, e = UsingBlocks.size(); i != e; ++i)
247 MarkDominatingPHILive(UsingBlocks[i], AllocaNum, InsertedPHINodes);
250 // If there are any PHI nodes which are now known to be dead, remove them!
251 for (std::set<PHINode*>::iterator I = InsertedPHINodes.begin(),
252 E = InsertedPHINodes.end(); I != E; ++I) {
254 std::vector<PHINode*> &BBPNs = NewPhiNodes[PN->getParent()];
255 BBPNs[AllocaNum] = 0;
257 // Check to see if we just removed the last inserted PHI node from this
258 // basic block. If so, remove the entry for the basic block.
259 bool HasOtherPHIs = false;
260 for (unsigned i = 0, e = BBPNs.size(); i != e; ++i)
266 NewPhiNodes.erase(PN->getParent());
268 if (AST && isa<PointerType>(PN->getType()))
269 AST->deleteValue(PN);
270 PN->getParent()->getInstList().erase(PN);
273 // Keep the reverse mapping of the 'Allocas' array.
274 AllocaLookup[Allocas[AllocaNum]] = AllocaNum;
277 // Process all allocas which are only used in a single basic block.
278 for (std::map<BasicBlock*, std::vector<AllocaInst*> >::iterator I =
279 LocallyUsedAllocas.begin(), E = LocallyUsedAllocas.end(); I != E; ++I){
280 const std::vector<AllocaInst*> &Allocas = I->second;
281 assert(!Allocas.empty() && "empty alloca list??");
283 // It's common for there to only be one alloca in the list. Handle it
285 if (Allocas.size() == 1)
286 PromoteLocallyUsedAlloca(I->first, Allocas[0]);
288 PromoteLocallyUsedAllocas(I->first, Allocas);
292 return; // All of the allocas must have been trivial!
294 // Set the incoming values for the basic block to be null values for all of
295 // the alloca's. We do this in case there is a load of a value that has not
296 // been stored yet. In this case, it will get this null value.
298 std::vector<Value *> Values(Allocas.size());
299 for (unsigned i = 0, e = Allocas.size(); i != e; ++i)
300 Values[i] = UndefValue::get(Allocas[i]->getAllocatedType());
302 // Walks all basic blocks in the function performing the SSA rename algorithm
303 // and inserting the phi nodes we marked as necessary
305 RenamePass(F.begin(), 0, Values);
307 // The renamer uses the Visited set to avoid infinite loops. Clear it now.
310 // Remove the allocas themselves from the function...
311 for (unsigned i = 0, e = Allocas.size(); i != e; ++i) {
312 Instruction *A = Allocas[i];
314 // If there are any uses of the alloca instructions left, they must be in
315 // sections of dead code that were not processed on the dominance frontier.
316 // Just delete the users now.
319 A->replaceAllUsesWith(UndefValue::get(A->getType()));
320 if (AST) AST->deleteValue(A);
321 A->getParent()->getInstList().erase(A);
324 // At this point, the renamer has added entries to PHI nodes for all reachable
325 // code. Unfortunately, there may be blocks which are not reachable, which
326 // the renamer hasn't traversed. If this is the case, the PHI nodes may not
327 // have incoming values for all predecessors. Loop over all PHI nodes we have
328 // created, inserting undef values if they are missing any incoming values.
330 for (std::map<BasicBlock*, std::vector<PHINode *> >::iterator I =
331 NewPhiNodes.begin(), E = NewPhiNodes.end(); I != E; ++I) {
333 std::vector<BasicBlock*> Preds(pred_begin(I->first), pred_end(I->first));
334 std::vector<PHINode*> &PNs = I->second;
335 assert(!PNs.empty() && "Empty PHI node list??");
337 // Loop over all of the PHI nodes and see if there are any that we can get
338 // rid of because they merge all of the same incoming values. This can
339 // happen due to undef values coming into the PHI nodes.
340 PHINode *SomePHI = 0;
341 for (unsigned i = 0, e = PNs.size(); i != e; ++i)
343 if (Value *V = hasConstantValue(PNs[i])) {
344 if (!isa<Instruction>(V) || dominates(cast<Instruction>(V), PNs[i])) {
345 if (AST && isa<PointerType>(PNs[i]->getType()))
346 AST->deleteValue(PNs[i]);
347 PNs[i]->replaceAllUsesWith(V);
348 PNs[i]->eraseFromParent();
356 // Only do work here if there the PHI nodes are missing incoming values. We
357 // know that all PHI nodes that were inserted in a block will have the same
358 // number of incoming values, so we can just check any PHI node.
359 if (SomePHI && Preds.size() != SomePHI->getNumIncomingValues()) {
360 // Ok, now we know that all of the PHI nodes are missing entries for some
361 // basic blocks. Start by sorting the incoming predecessors for efficient
363 std::sort(Preds.begin(), Preds.end());
365 // Now we loop through all BB's which have entries in SomePHI and remove
366 // them from the Preds list.
367 for (unsigned i = 0, e = SomePHI->getNumIncomingValues(); i != e; ++i) {
368 // Do a log(n) search of the Preds list for the entry we want.
369 std::vector<BasicBlock*>::iterator EntIt =
370 std::lower_bound(Preds.begin(), Preds.end(),
371 SomePHI->getIncomingBlock(i));
372 assert(EntIt != Preds.end() && *EntIt == SomePHI->getIncomingBlock(i)&&
373 "PHI node has entry for a block which is not a predecessor!");
379 // At this point, the blocks left in the preds list must have dummy
380 // entries inserted into every PHI nodes for the block.
381 for (unsigned i = 0, e = PNs.size(); i != e; ++i)
382 if (PHINode *PN = PNs[i]) {
383 Value *UndefVal = UndefValue::get(PN->getType());
384 for (unsigned pred = 0, e = Preds.size(); pred != e; ++pred)
385 PN->addIncoming(UndefVal, Preds[pred]);
391 // MarkDominatingPHILive - Mem2Reg wants to construct "pruned" SSA form, not
392 // "minimal" SSA form. To do this, it inserts all of the PHI nodes on the IDF
393 // as usual (inserting the PHI nodes in the DeadPHINodes set), then processes
394 // each read of the variable. For each block that reads the variable, this
395 // function is called, which removes used PHI nodes from the DeadPHINodes set.
396 // After all of the reads have been processed, any PHI nodes left in the
397 // DeadPHINodes set are removed.
399 void PromoteMem2Reg::MarkDominatingPHILive(BasicBlock *BB, unsigned AllocaNum,
400 std::set<PHINode*> &DeadPHINodes) {
401 // Scan the immediate dominators of this block looking for a block which has a
402 // PHI node for Alloca num. If we find it, mark the PHI node as being alive!
403 for (DominatorTree::Node *N = DT[BB]; N; N = N->getIDom()) {
404 BasicBlock *DomBB = N->getBlock();
405 std::map<BasicBlock*, std::vector<PHINode*> >::iterator
406 I = NewPhiNodes.find(DomBB);
407 if (I != NewPhiNodes.end() && I->second[AllocaNum]) {
408 // Ok, we found an inserted PHI node which dominates this value.
409 PHINode *DominatingPHI = I->second[AllocaNum];
411 // Find out if we previously thought it was dead.
412 std::set<PHINode*>::iterator DPNI = DeadPHINodes.find(DominatingPHI);
413 if (DPNI != DeadPHINodes.end()) {
414 // Ok, until now, we thought this PHI node was dead. Mark it as being
416 DeadPHINodes.erase(DPNI);
418 // Now that we have marked the PHI node alive, also mark any PHI nodes
419 // which it might use as being alive as well.
420 for (pred_iterator PI = pred_begin(DomBB), PE = pred_end(DomBB);
422 MarkDominatingPHILive(*PI, AllocaNum, DeadPHINodes);
428 /// PromoteLocallyUsedAlloca - Many allocas are only used within a single basic
429 /// block. If this is the case, avoid traversing the CFG and inserting a lot of
430 /// potentially useless PHI nodes by just performing a single linear pass over
431 /// the basic block using the Alloca.
433 void PromoteMem2Reg::PromoteLocallyUsedAlloca(BasicBlock *BB, AllocaInst *AI) {
434 assert(!AI->use_empty() && "There are no uses of the alloca!");
436 // Handle degenerate cases quickly.
437 if (AI->hasOneUse()) {
438 Instruction *U = cast<Instruction>(AI->use_back());
439 if (LoadInst *LI = dyn_cast<LoadInst>(U)) {
440 // Must be a load of uninitialized value.
441 LI->replaceAllUsesWith(UndefValue::get(AI->getAllocatedType()));
442 if (AST && isa<PointerType>(LI->getType()))
443 AST->deleteValue(LI);
445 // Otherwise it must be a store which is never read.
446 assert(isa<StoreInst>(U));
448 BB->getInstList().erase(U);
450 // Uses of the uninitialized memory location shall get undef.
451 Value *CurVal = UndefValue::get(AI->getAllocatedType());
453 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
454 Instruction *Inst = I++;
455 if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
456 if (LI->getOperand(0) == AI) {
457 // Loads just returns the "current value"...
458 LI->replaceAllUsesWith(CurVal);
459 if (AST && isa<PointerType>(LI->getType()))
460 AST->deleteValue(LI);
461 BB->getInstList().erase(LI);
463 } else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
464 if (SI->getOperand(1) == AI) {
465 // Store updates the "current value"...
466 CurVal = SI->getOperand(0);
467 BB->getInstList().erase(SI);
473 // After traversing the basic block, there should be no more uses of the
474 // alloca, remove it now.
475 assert(AI->use_empty() && "Uses of alloca from more than one BB??");
476 if (AST) AST->deleteValue(AI);
477 AI->getParent()->getInstList().erase(AI);
480 /// PromoteLocallyUsedAllocas - This method is just like
481 /// PromoteLocallyUsedAlloca, except that it processes multiple alloca
482 /// instructions in parallel. This is important in cases where we have large
483 /// basic blocks, as we don't want to rescan the entire basic block for each
484 /// alloca which is locally used in it (which might be a lot).
485 void PromoteMem2Reg::
486 PromoteLocallyUsedAllocas(BasicBlock *BB, const std::vector<AllocaInst*> &AIs) {
487 std::map<AllocaInst*, Value*> CurValues;
488 for (unsigned i = 0, e = AIs.size(); i != e; ++i)
489 CurValues[AIs[i]] = 0; // Insert with null value
491 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ) {
492 Instruction *Inst = I++;
493 if (LoadInst *LI = dyn_cast<LoadInst>(Inst)) {
494 // Is this a load of an alloca we are tracking?
495 if (AllocaInst *AI = dyn_cast<AllocaInst>(LI->getOperand(0))) {
496 std::map<AllocaInst*, Value*>::iterator AIt = CurValues.find(AI);
497 if (AIt != CurValues.end()) {
498 // Loads just returns the "current value"...
499 if (AIt->second == 0) // Uninitialized value??
500 AIt->second = UndefValue::get(AIt->first->getAllocatedType());
501 LI->replaceAllUsesWith(AIt->second);
502 if (AST && isa<PointerType>(LI->getType()))
503 AST->deleteValue(LI);
504 BB->getInstList().erase(LI);
507 } else if (StoreInst *SI = dyn_cast<StoreInst>(Inst)) {
508 if (AllocaInst *AI = dyn_cast<AllocaInst>(SI->getOperand(1))) {
509 std::map<AllocaInst*, Value*>::iterator AIt = CurValues.find(AI);
510 if (AIt != CurValues.end()) {
511 // Store updates the "current value"...
512 AIt->second = SI->getOperand(0);
513 BB->getInstList().erase(SI);
522 // QueuePhiNode - queues a phi-node to be added to a basic-block for a specific
523 // Alloca returns true if there wasn't already a phi-node for that variable
525 bool PromoteMem2Reg::QueuePhiNode(BasicBlock *BB, unsigned AllocaNo,
527 std::set<PHINode*> &InsertedPHINodes) {
528 // Look up the basic-block in question.
529 std::vector<PHINode*> &BBPNs = NewPhiNodes[BB];
530 if (BBPNs.empty()) BBPNs.resize(Allocas.size());
532 // If the BB already has a phi node added for the i'th alloca then we're done!
533 if (BBPNs[AllocaNo]) return false;
535 // Create a PhiNode using the dereferenced type... and add the phi-node to the
537 PHINode *PN = new PHINode(Allocas[AllocaNo]->getAllocatedType(),
538 Allocas[AllocaNo]->getName() + "." +
539 utostr(Version++), BB->begin());
540 BBPNs[AllocaNo] = PN;
541 InsertedPHINodes.insert(PN);
543 if (AST && isa<PointerType>(PN->getType()))
544 AST->copyValue(PointerAllocaValues[AllocaNo], PN);
550 // RenamePass - Recursively traverse the CFG of the function, renaming loads and
551 // stores to the allocas which we are promoting. IncomingVals indicates what
552 // value each Alloca contains on exit from the predecessor block Pred.
554 void PromoteMem2Reg::RenamePass(BasicBlock *BB, BasicBlock *Pred,
555 std::vector<Value*> &IncomingVals) {
557 // If this BB needs a PHI node, update the PHI node for each variable we need
559 std::map<BasicBlock*, std::vector<PHINode *> >::iterator
560 BBPNI = NewPhiNodes.find(BB);
561 if (BBPNI != NewPhiNodes.end()) {
562 std::vector<PHINode *> &BBPNs = BBPNI->second;
563 for (unsigned k = 0; k != BBPNs.size(); ++k)
564 if (PHINode *PN = BBPNs[k]) {
565 // Add this incoming value to the PHI node.
566 PN->addIncoming(IncomingVals[k], Pred);
568 // The currently active variable for this block is now the PHI.
569 IncomingVals[k] = PN;
573 // don't revisit nodes
574 if (Visited.count(BB)) return;
579 for (BasicBlock::iterator II = BB->begin(); !isa<TerminatorInst>(II); ) {
580 Instruction *I = II++; // get the instruction, increment iterator
582 if (LoadInst *LI = dyn_cast<LoadInst>(I)) {
583 if (AllocaInst *Src = dyn_cast<AllocaInst>(LI->getPointerOperand())) {
584 std::map<AllocaInst*, unsigned>::iterator AI = AllocaLookup.find(Src);
585 if (AI != AllocaLookup.end()) {
586 Value *V = IncomingVals[AI->second];
588 // walk the use list of this load and replace all uses with r
589 LI->replaceAllUsesWith(V);
590 if (AST && isa<PointerType>(LI->getType()))
591 AST->deleteValue(LI);
592 BB->getInstList().erase(LI);
595 } else if (StoreInst *SI = dyn_cast<StoreInst>(I)) {
596 // Delete this instruction and mark the name as the current holder of the
598 if (AllocaInst *Dest = dyn_cast<AllocaInst>(SI->getPointerOperand())) {
599 std::map<AllocaInst *, unsigned>::iterator ai = AllocaLookup.find(Dest);
600 if (ai != AllocaLookup.end()) {
601 // what value were we writing?
602 IncomingVals[ai->second] = SI->getOperand(0);
603 BB->getInstList().erase(SI);
609 // Recurse to our successors.
610 TerminatorInst *TI = BB->getTerminator();
611 for (unsigned i = 0; i != TI->getNumSuccessors(); i++) {
612 std::vector<Value*> OutgoingVals(IncomingVals);
613 RenamePass(TI->getSuccessor(i), BB, OutgoingVals);
617 /// PromoteMemToReg - Promote the specified list of alloca instructions into
618 /// scalar registers, inserting PHI nodes as appropriate. This function makes
619 /// use of DominanceFrontier information. This function does not modify the CFG
620 /// of the function at all. All allocas must be from the same function.
622 /// If AST is specified, the specified tracker is updated to reflect changes
625 void llvm::PromoteMemToReg(const std::vector<AllocaInst*> &Allocas,
626 DominatorTree &DT, DominanceFrontier &DF,
627 const TargetData &TD, AliasSetTracker *AST) {
628 // If there is nothing to do, bail out...
629 if (Allocas.empty()) return;
630 PromoteMem2Reg(Allocas, DT, DF, TD, AST).run();