1 //===- CorrelatedExprs.cpp - Pass to detect and eliminated c.e.'s ---------===//
3 // Correlated Expression Elimination propagates information from conditional
4 // branches to blocks dominated by destinations of the branch. It propagates
5 // information from the condition check itself into the body of the branch,
6 // allowing transformations like these for example:
9 // ... 4*i; // constant propagation
13 // X = M-N; // = M-M == 0;
15 // This is called Correlated Expression Elimination because we eliminate or
16 // simplify expressions that are correlated with the direction of a branch. In
17 // this way we use static information to give us some information about the
18 // dynamic value of a variable.
20 //===----------------------------------------------------------------------===//
22 #include "llvm/Transforms/Scalar.h"
23 #include "llvm/Pass.h"
24 #include "llvm/Function.h"
25 #include "llvm/iTerminators.h"
26 #include "llvm/iPHINode.h"
27 #include "llvm/iOperators.h"
28 #include "llvm/ConstantHandling.h"
29 #include "llvm/Assembly/Writer.h"
30 #include "llvm/Analysis/Dominators.h"
31 #include "llvm/Transforms/Utils/Local.h"
32 #include "llvm/Support/ConstantRange.h"
33 #include "llvm/Support/CFG.h"
34 #include "Support/Debug.h"
35 #include "Support/PostOrderIterator.h"
36 #include "Support/Statistic.h"
40 Statistic<> NumSetCCRemoved("cee", "Number of setcc instruction eliminated");
41 Statistic<> NumOperandsCann("cee", "Number of operands canonicalized");
42 Statistic<> BranchRevectors("cee", "Number of branches revectored");
46 Value *Val; // Relation to what value?
47 Instruction::BinaryOps Rel; // SetCC relation, or Add if no information
49 Relation(Value *V) : Val(V), Rel(Instruction::Add) {}
50 bool operator<(const Relation &R) const { return Val < R.Val; }
51 Value *getValue() const { return Val; }
52 Instruction::BinaryOps getRelation() const { return Rel; }
54 // contradicts - Return true if the relationship specified by the operand
55 // contradicts already known information.
57 bool contradicts(Instruction::BinaryOps Rel, const ValueInfo &VI) const;
59 // incorporate - Incorporate information in the argument into this relation
60 // entry. This assumes that the information doesn't contradict itself. If
61 // any new information is gained, true is returned, otherwise false is
62 // returned to indicate that nothing was updated.
64 bool incorporate(Instruction::BinaryOps Rel, ValueInfo &VI);
66 // KnownResult - Whether or not this condition determines the result of a
67 // setcc in the program. False & True are intentionally 0 & 1 so we can
68 // convert to bool by casting after checking for unknown.
70 enum KnownResult { KnownFalse = 0, KnownTrue = 1, Unknown = 2 };
72 // getImpliedResult - If this relationship between two values implies that
73 // the specified relationship is true or false, return that. If we cannot
74 // determine the result required, return Unknown.
76 KnownResult getImpliedResult(Instruction::BinaryOps Rel) const;
78 // print - Output this relation to the specified stream
79 void print(std::ostream &OS) const;
84 // ValueInfo - One instance of this record exists for every value with
85 // relationships between other values. It keeps track of all of the
86 // relationships to other values in the program (specified with Relation) that
87 // are known to be valid in a region.
90 // RelationShips - this value is know to have the specified relationships to
91 // other values. There can only be one entry per value, and this list is
92 // kept sorted by the Val field.
93 std::vector<Relation> Relationships;
95 // If information about this value is known or propagated from constant
96 // expressions, this range contains the possible values this value may hold.
99 // If we find that this value is equal to another value that has a lower
100 // rank, this value is used as it's replacement.
104 ValueInfo(const Type *Ty)
105 : Bounds(Ty->isIntegral() ? Ty : Type::IntTy), Replacement(0) {}
107 // getBounds() - Return the constant bounds of the value...
108 const ConstantRange &getBounds() const { return Bounds; }
109 ConstantRange &getBounds() { return Bounds; }
111 const std::vector<Relation> &getRelationships() { return Relationships; }
113 // getReplacement - Return the value this value is to be replaced with if it
114 // exists, otherwise return null.
116 Value *getReplacement() const { return Replacement; }
118 // setReplacement - Used by the replacement calculation pass to figure out
119 // what to replace this value with, if anything.
121 void setReplacement(Value *Repl) { Replacement = Repl; }
123 // getRelation - return the relationship entry for the specified value.
124 // This can invalidate references to other Relation's, so use it carefully.
126 Relation &getRelation(Value *V) {
127 // Binary search for V's entry...
128 std::vector<Relation>::iterator I =
129 std::lower_bound(Relationships.begin(), Relationships.end(), V);
131 // If we found the entry, return it...
132 if (I != Relationships.end() && I->getValue() == V)
135 // Insert and return the new relationship...
136 return *Relationships.insert(I, V);
139 const Relation *requestRelation(Value *V) const {
140 // Binary search for V's entry...
141 std::vector<Relation>::const_iterator I =
142 std::lower_bound(Relationships.begin(), Relationships.end(), V);
143 if (I != Relationships.end() && I->getValue() == V)
148 // print - Output information about this value relation...
149 void print(std::ostream &OS, Value *V) const;
153 // RegionInfo - Keeps track of all of the value relationships for a region. A
154 // region is the are dominated by a basic block. RegionInfo's keep track of
155 // the RegionInfo for their dominator, because anything known in a dominator
156 // is known to be true in a dominated block as well.
161 // ValueMap - Tracks the ValueInformation known for this region
162 typedef std::map<Value*, ValueInfo> ValueMapTy;
165 RegionInfo(BasicBlock *bb) : BB(bb) {}
167 // getEntryBlock - Return the block that dominates all of the members of
169 BasicBlock *getEntryBlock() const { return BB; }
171 // empty - return true if this region has no information known about it.
172 bool empty() const { return ValueMap.empty(); }
174 const RegionInfo &operator=(const RegionInfo &RI) {
175 ValueMap = RI.ValueMap;
179 // print - Output information about this region...
180 void print(std::ostream &OS) const;
183 // Allow external access.
184 typedef ValueMapTy::iterator iterator;
185 iterator begin() { return ValueMap.begin(); }
186 iterator end() { return ValueMap.end(); }
188 ValueInfo &getValueInfo(Value *V) {
189 ValueMapTy::iterator I = ValueMap.lower_bound(V);
190 if (I != ValueMap.end() && I->first == V) return I->second;
191 return ValueMap.insert(I, std::make_pair(V, V->getType()))->second;
194 const ValueInfo *requestValueInfo(Value *V) const {
195 ValueMapTy::const_iterator I = ValueMap.find(V);
196 if (I != ValueMap.end()) return &I->second;
200 /// removeValueInfo - Remove anything known about V from our records. This
201 /// works whether or not we know anything about V.
203 void removeValueInfo(Value *V) {
208 /// CEE - Correlated Expression Elimination
209 class CEE : public FunctionPass {
210 std::map<Value*, unsigned> RankMap;
211 std::map<BasicBlock*, RegionInfo> RegionInfoMap;
215 virtual bool runOnFunction(Function &F);
217 // We don't modify the program, so we preserve all analyses
218 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
219 AU.addRequired<DominatorSet>();
220 AU.addRequired<DominatorTree>();
221 AU.addRequiredID(BreakCriticalEdgesID);
224 // print - Implement the standard print form to print out analysis
226 virtual void print(std::ostream &O, const Module *M) const;
229 RegionInfo &getRegionInfo(BasicBlock *BB) {
230 std::map<BasicBlock*, RegionInfo>::iterator I
231 = RegionInfoMap.lower_bound(BB);
232 if (I != RegionInfoMap.end() && I->first == BB) return I->second;
233 return RegionInfoMap.insert(I, std::make_pair(BB, BB))->second;
236 void BuildRankMap(Function &F);
237 unsigned getRank(Value *V) const {
238 if (isa<Constant>(V) || isa<GlobalValue>(V)) return 0;
239 std::map<Value*, unsigned>::const_iterator I = RankMap.find(V);
240 if (I != RankMap.end()) return I->second;
241 return 0; // Must be some other global thing
244 bool TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks);
246 bool ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
249 void ForwardSuccessorTo(TerminatorInst *TI, unsigned Succ, BasicBlock *D,
251 void ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
252 BasicBlock *RegionDominator);
253 void CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
254 std::vector<BasicBlock*> &RegionExitBlocks);
255 void InsertRegionExitMerges(PHINode *NewPHI, Instruction *OldVal,
256 const std::vector<BasicBlock*> &RegionExitBlocks);
258 void PropagateBranchInfo(BranchInst *BI);
259 void PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI);
260 void PropagateRelation(Instruction::BinaryOps Opcode, Value *Op0,
261 Value *Op1, RegionInfo &RI);
262 void UpdateUsersOfValue(Value *V, RegionInfo &RI);
263 void IncorporateInstruction(Instruction *Inst, RegionInfo &RI);
264 void ComputeReplacements(RegionInfo &RI);
267 // getSetCCResult - Given a setcc instruction, determine if the result is
268 // determined by facts we already know about the region under analysis.
269 // Return KnownTrue, KnownFalse, or Unknown based on what we can determine.
271 Relation::KnownResult getSetCCResult(SetCondInst *SC, const RegionInfo &RI);
274 bool SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI);
275 bool SimplifyInstruction(Instruction *Inst, const RegionInfo &RI);
277 RegisterOpt<CEE> X("cee", "Correlated Expression Elimination");
280 Pass *createCorrelatedExpressionEliminationPass() { return new CEE(); }
283 bool CEE::runOnFunction(Function &F) {
284 // Build a rank map for the function...
287 // Traverse the dominator tree, computing information for each node in the
288 // tree. Note that our traversal will not even touch unreachable basic
290 DS = &getAnalysis<DominatorSet>();
291 DT = &getAnalysis<DominatorTree>();
293 std::set<BasicBlock*> VisitedBlocks;
294 bool Changed = TransformRegion(&F.getEntryBlock(), VisitedBlocks);
296 RegionInfoMap.clear();
301 // TransformRegion - Transform the region starting with BB according to the
302 // calculated region information for the block. Transforming the region
303 // involves analyzing any information this block provides to successors,
304 // propagating the information to successors, and finally transforming
307 // This method processes the function in depth first order, which guarantees
308 // that we process the immediate dominator of a block before the block itself.
309 // Because we are passing information from immediate dominators down to
310 // dominatees, we obviously have to process the information source before the
311 // information consumer.
313 bool CEE::TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks){
314 // Prevent infinite recursion...
315 if (VisitedBlocks.count(BB)) return false;
316 VisitedBlocks.insert(BB);
318 // Get the computed region information for this block...
319 RegionInfo &RI = getRegionInfo(BB);
321 // Compute the replacement information for this block...
322 ComputeReplacements(RI);
324 // If debugging, print computed region information...
325 DEBUG(RI.print(std::cerr));
327 // Simplify the contents of this block...
328 bool Changed = SimplifyBasicBlock(*BB, RI);
330 // Get the terminator of this basic block...
331 TerminatorInst *TI = BB->getTerminator();
333 // Loop over all of the blocks that this block is the immediate dominator for.
334 // Because all information known in this region is also known in all of the
335 // blocks that are dominated by this one, we can safely propagate the
336 // information down now.
338 DominatorTree::Node *BBN = (*DT)[BB];
339 if (!RI.empty()) // Time opt: only propagate if we can change something
340 for (unsigned i = 0, e = BBN->getChildren().size(); i != e; ++i) {
341 BasicBlock *Dominated = BBN->getChildren()[i]->getBlock();
342 assert(RegionInfoMap.find(Dominated) == RegionInfoMap.end() &&
343 "RegionInfo should be calculated in dominanace order!");
344 getRegionInfo(Dominated) = RI;
347 // Now that all of our successors have information if they deserve it,
348 // propagate any information our terminator instruction finds to our
350 if (BranchInst *BI = dyn_cast<BranchInst>(TI))
351 if (BI->isConditional())
352 PropagateBranchInfo(BI);
354 // If this is a branch to a block outside our region that simply performs
355 // another conditional branch, one whose outcome is known inside of this
356 // region, then vector this outgoing edge directly to the known destination.
358 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
359 while (ForwardCorrelatedEdgeDestination(TI, i, RI)) {
364 // Now that all of our successors have information, recursively process them.
365 for (unsigned i = 0, e = BBN->getChildren().size(); i != e; ++i)
366 Changed |= TransformRegion(BBN->getChildren()[i]->getBlock(),VisitedBlocks);
371 // isBlockSimpleEnoughForCheck to see if the block is simple enough for us to
372 // revector the conditional branch in the bottom of the block, do so now.
374 static bool isBlockSimpleEnough(BasicBlock *BB) {
375 assert(isa<BranchInst>(BB->getTerminator()));
376 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
377 assert(BI->isConditional());
379 // Check the common case first: empty block, or block with just a setcc.
380 if (BB->size() == 1 ||
381 (BB->size() == 2 && &BB->front() == BI->getCondition() &&
382 BI->getCondition()->use_size() == 1))
385 // Check the more complex case now...
386 BasicBlock::iterator I = BB->begin();
388 // FIXME: This should be reenabled once the regression with SIM is fixed!
390 // PHI Nodes are ok, just skip over them...
391 while (isa<PHINode>(*I)) ++I;
394 // Accept the setcc instruction...
395 if (&*I == BI->getCondition())
398 // Nothing else is acceptable here yet. We must not revector... unless we are
399 // at the terminator instruction.
407 bool CEE::ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
409 // If this successor is a simple block not in the current region, which
410 // contains only a conditional branch, we decide if the outcome of the branch
411 // can be determined from information inside of the region. Instead of going
412 // to this block, we can instead go to the destination we know is the right
416 // Check to see if we dominate the block. If so, this block will get the
417 // condition turned to a constant anyway.
419 //if (DS->dominates(RI.getEntryBlock(), BB))
422 BasicBlock *BB = TI->getParent();
424 // Get the destination block of this edge...
425 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
427 // Make sure that the block ends with a conditional branch and is simple
428 // enough for use to be able to revector over.
429 BranchInst *BI = dyn_cast<BranchInst>(OldSucc->getTerminator());
430 if (BI == 0 || !BI->isConditional() || !isBlockSimpleEnough(OldSucc))
433 // We can only forward the branch over the block if the block ends with a
434 // setcc we can determine the outcome for.
436 // FIXME: we can make this more generic. Code below already handles more
438 SetCondInst *SCI = dyn_cast<SetCondInst>(BI->getCondition());
439 if (SCI == 0) return false;
441 // Make a new RegionInfo structure so that we can simulate the effect of the
442 // PHI nodes in the block we are skipping over...
444 RegionInfo NewRI(RI);
446 // Remove value information for all of the values we are simulating... to make
447 // sure we don't have any stale information.
448 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
449 if (I->getType() != Type::VoidTy)
450 NewRI.removeValueInfo(I);
452 // Put the newly discovered information into the RegionInfo...
453 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
454 if (PHINode *PN = dyn_cast<PHINode>(I)) {
455 int OpNum = PN->getBasicBlockIndex(BB);
456 assert(OpNum != -1 && "PHI doesn't have incoming edge for predecessor!?");
457 PropagateEquality(PN, PN->getIncomingValue(OpNum), NewRI);
458 } else if (SetCondInst *SCI = dyn_cast<SetCondInst>(I)) {
459 Relation::KnownResult Res = getSetCCResult(SCI, NewRI);
460 if (Res == Relation::Unknown) return false;
461 PropagateEquality(SCI, ConstantBool::get(Res), NewRI);
463 assert(isa<BranchInst>(*I) && "Unexpected instruction type!");
466 // Compute the facts implied by what we have discovered...
467 ComputeReplacements(NewRI);
469 ValueInfo &PredicateVI = NewRI.getValueInfo(BI->getCondition());
470 if (PredicateVI.getReplacement() &&
471 isa<Constant>(PredicateVI.getReplacement())) {
472 ConstantBool *CB = cast<ConstantBool>(PredicateVI.getReplacement());
474 // Forward to the successor that corresponds to the branch we will take.
475 ForwardSuccessorTo(TI, SuccNo, BI->getSuccessor(!CB->getValue()), NewRI);
482 static Value *getReplacementOrValue(Value *V, RegionInfo &RI) {
483 if (const ValueInfo *VI = RI.requestValueInfo(V))
484 if (Value *Repl = VI->getReplacement())
489 /// ForwardSuccessorTo - We have found that we can forward successor # 'SuccNo'
490 /// of Terminator 'TI' to the 'Dest' BasicBlock. This method performs the
491 /// mechanics of updating SSA information and revectoring the branch.
493 void CEE::ForwardSuccessorTo(TerminatorInst *TI, unsigned SuccNo,
494 BasicBlock *Dest, RegionInfo &RI) {
495 // If there are any PHI nodes in the Dest BB, we must duplicate the entry
496 // in the PHI node for the old successor to now include an entry from the
497 // current basic block.
499 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
500 BasicBlock *BB = TI->getParent();
502 DEBUG(std::cerr << "Forwarding branch in basic block %" << BB->getName()
503 << " from block %" << OldSucc->getName() << " to block %"
504 << Dest->getName() << "\n");
506 DEBUG(std::cerr << "Before forwarding: " << *BB->getParent());
508 // Because we know that there cannot be critical edges in the flow graph, and
509 // that OldSucc has multiple outgoing edges, this means that Dest cannot have
510 // multiple incoming edges.
513 pred_iterator DPI = pred_begin(Dest); ++DPI;
514 assert(DPI == pred_end(Dest) && "Critical edge found!!");
517 // Loop over any PHI nodes in the destination, eliminating them, because they
518 // may only have one input.
520 while (PHINode *PN = dyn_cast<PHINode>(&Dest->front())) {
521 assert(PN->getNumIncomingValues() == 1 && "Crit edge found!");
522 // Eliminate the PHI node
523 PN->replaceAllUsesWith(PN->getIncomingValue(0));
524 Dest->getInstList().erase(PN);
527 // If there are values defined in the "OldSucc" basic block, we need to insert
528 // PHI nodes in the regions we are dealing with to emulate them. This can
529 // insert dead phi nodes, but it is more trouble to see if they are used than
530 // to just blindly insert them.
532 if (DS->dominates(OldSucc, Dest)) {
533 // RegionExitBlocks - Find all of the blocks that are not dominated by Dest,
534 // but have predecessors that are. Additionally, prune down the set to only
535 // include blocks that are dominated by OldSucc as well.
537 std::vector<BasicBlock*> RegionExitBlocks;
538 CalculateRegionExitBlocks(Dest, OldSucc, RegionExitBlocks);
540 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end();
542 if (I->getType() != Type::VoidTy) {
543 // Create and insert the PHI node into the top of Dest.
544 PHINode *NewPN = new PHINode(I->getType(), I->getName()+".fw_merge",
546 // There is definitely an edge from OldSucc... add the edge now
547 NewPN->addIncoming(I, OldSucc);
549 // There is also an edge from BB now, add the edge with the calculated
550 // value from the RI.
551 NewPN->addIncoming(getReplacementOrValue(I, RI), BB);
553 // Make everything in the Dest region use the new PHI node now...
554 ReplaceUsesOfValueInRegion(I, NewPN, Dest);
556 // Make sure that exits out of the region dominated by NewPN get PHI
557 // nodes that merge the values as appropriate.
558 InsertRegionExitMerges(NewPN, I, RegionExitBlocks);
562 // If there were PHI nodes in OldSucc, we need to remove the entry for this
563 // edge from the PHI node, and we need to replace any references to the PHI
564 // node with a new value.
566 for (BasicBlock::iterator I = OldSucc->begin();
567 PHINode *PN = dyn_cast<PHINode>(I); ) {
569 // Get the value flowing across the old edge and remove the PHI node entry
570 // for this edge: we are about to remove the edge! Don't remove the PHI
571 // node yet though if this is the last edge into it.
572 Value *EdgeValue = PN->removeIncomingValue(BB, false);
574 // Make sure that anything that used to use PN now refers to EdgeValue
575 ReplaceUsesOfValueInRegion(PN, EdgeValue, Dest);
577 // If there is only one value left coming into the PHI node, replace the PHI
578 // node itself with the one incoming value left.
580 if (PN->getNumIncomingValues() == 1) {
581 assert(PN->getNumIncomingValues() == 1);
582 PN->replaceAllUsesWith(PN->getIncomingValue(0));
583 PN->getParent()->getInstList().erase(PN);
584 I = OldSucc->begin();
585 } else if (PN->getNumIncomingValues() == 0) { // Nuke the PHI
586 // If we removed the last incoming value to this PHI, nuke the PHI node
588 PN->replaceAllUsesWith(Constant::getNullValue(PN->getType()));
589 PN->getParent()->getInstList().erase(PN);
590 I = OldSucc->begin();
592 ++I; // Otherwise, move on to the next PHI node
596 // Actually revector the branch now...
597 TI->setSuccessor(SuccNo, Dest);
599 // If we just introduced a critical edge in the flow graph, make sure to break
601 if (isCriticalEdge(TI, SuccNo))
602 SplitCriticalEdge(TI, SuccNo, this);
604 // Make sure that we don't introduce critical edges from oldsucc now!
605 for (unsigned i = 0, e = OldSucc->getTerminator()->getNumSuccessors();
607 if (isCriticalEdge(OldSucc->getTerminator(), i))
608 SplitCriticalEdge(OldSucc->getTerminator(), i, this);
610 // Since we invalidated the CFG, recalculate the dominator set so that it is
611 // useful for later processing!
612 // FIXME: This is much worse than it really should be!
615 DEBUG(std::cerr << "After forwarding: " << *BB->getParent());
618 /// ReplaceUsesOfValueInRegion - This method replaces all uses of Orig with uses
619 /// of New. It only affects instructions that are defined in basic blocks that
620 /// are dominated by Head.
622 void CEE::ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
623 BasicBlock *RegionDominator) {
624 assert(Orig != New && "Cannot replace value with itself");
625 std::vector<Instruction*> InstsToChange;
626 std::vector<PHINode*> PHIsToChange;
627 InstsToChange.reserve(Orig->use_size());
629 // Loop over instructions adding them to InstsToChange vector, this allows us
630 // an easy way to avoid invalidating the use_iterator at a bad time.
631 for (Value::use_iterator I = Orig->use_begin(), E = Orig->use_end();
633 if (Instruction *User = dyn_cast<Instruction>(*I))
634 if (DS->dominates(RegionDominator, User->getParent()))
635 InstsToChange.push_back(User);
636 else if (PHINode *PN = dyn_cast<PHINode>(User)) {
637 PHIsToChange.push_back(PN);
640 // PHIsToChange contains PHI nodes that use Orig that do not live in blocks
641 // dominated by orig. If the block the value flows in from is dominated by
642 // RegionDominator, then we rewrite the PHI
643 for (unsigned i = 0, e = PHIsToChange.size(); i != e; ++i) {
644 PHINode *PN = PHIsToChange[i];
645 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
646 if (PN->getIncomingValue(j) == Orig &&
647 DS->dominates(RegionDominator, PN->getIncomingBlock(j)))
648 PN->setIncomingValue(j, New);
651 // Loop over the InstsToChange list, replacing all uses of Orig with uses of
652 // New. This list contains all of the instructions in our region that use
654 for (unsigned i = 0, e = InstsToChange.size(); i != e; ++i)
655 if (PHINode *PN = dyn_cast<PHINode>(InstsToChange[i])) {
656 // PHINodes must be handled carefully. If the PHI node itself is in the
657 // region, we have to make sure to only do the replacement for incoming
658 // values that correspond to basic blocks in the region.
659 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
660 if (PN->getIncomingValue(j) == Orig &&
661 DS->dominates(RegionDominator, PN->getIncomingBlock(j)))
662 PN->setIncomingValue(j, New);
665 InstsToChange[i]->replaceUsesOfWith(Orig, New);
669 static void CalcRegionExitBlocks(BasicBlock *Header, BasicBlock *BB,
670 std::set<BasicBlock*> &Visited,
672 std::vector<BasicBlock*> &RegionExitBlocks) {
673 if (Visited.count(BB)) return;
676 if (DS.dominates(Header, BB)) { // Block in the region, recursively traverse
677 for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
678 CalcRegionExitBlocks(Header, *I, Visited, DS, RegionExitBlocks);
680 // Header does not dominate this block, but we have a predecessor that does
681 // dominate us. Add ourself to the list.
682 RegionExitBlocks.push_back(BB);
686 /// CalculateRegionExitBlocks - Find all of the blocks that are not dominated by
687 /// BB, but have predecessors that are. Additionally, prune down the set to
688 /// only include blocks that are dominated by OldSucc as well.
690 void CEE::CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
691 std::vector<BasicBlock*> &RegionExitBlocks){
692 std::set<BasicBlock*> Visited; // Don't infinite loop
694 // Recursively calculate blocks we are interested in...
695 CalcRegionExitBlocks(BB, BB, Visited, *DS, RegionExitBlocks);
697 // Filter out blocks that are not dominated by OldSucc...
698 for (unsigned i = 0; i != RegionExitBlocks.size(); ) {
699 if (DS->dominates(OldSucc, RegionExitBlocks[i]))
700 ++i; // Block is ok, keep it.
702 // Move to end of list...
703 std::swap(RegionExitBlocks[i], RegionExitBlocks.back());
704 RegionExitBlocks.pop_back(); // Nuke the end
709 void CEE::InsertRegionExitMerges(PHINode *BBVal, Instruction *OldVal,
710 const std::vector<BasicBlock*> &RegionExitBlocks) {
711 assert(BBVal->getType() == OldVal->getType() && "Should be derived values!");
712 BasicBlock *BB = BBVal->getParent();
713 BasicBlock *OldSucc = OldVal->getParent();
715 // Loop over all of the blocks we have to place PHIs in, doing it.
716 for (unsigned i = 0, e = RegionExitBlocks.size(); i != e; ++i) {
717 BasicBlock *FBlock = RegionExitBlocks[i]; // Block on the frontier
719 // Create the new PHI node
720 PHINode *NewPN = new PHINode(BBVal->getType(),
721 OldVal->getName()+".fw_frontier",
724 // Add an incoming value for every predecessor of the block...
725 for (pred_iterator PI = pred_begin(FBlock), PE = pred_end(FBlock);
727 // If the incoming edge is from the region dominated by BB, use BBVal,
728 // otherwise use OldVal.
729 NewPN->addIncoming(DS->dominates(BB, *PI) ? BBVal : OldVal, *PI);
732 // Now make everyone dominated by this block use this new value!
733 ReplaceUsesOfValueInRegion(OldVal, NewPN, FBlock);
739 // BuildRankMap - This method builds the rank map data structure which gives
740 // each instruction/value in the function a value based on how early it appears
741 // in the function. We give constants and globals rank 0, arguments are
742 // numbered starting at one, and instructions are numbered in reverse post-order
743 // from where the arguments leave off. This gives instructions in loops higher
744 // values than instructions not in loops.
746 void CEE::BuildRankMap(Function &F) {
747 unsigned Rank = 1; // Skip rank zero.
749 // Number the arguments...
750 for (Function::aiterator I = F.abegin(), E = F.aend(); I != E; ++I)
753 // Number the instructions in reverse post order...
754 ReversePostOrderTraversal<Function*> RPOT(&F);
755 for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
756 E = RPOT.end(); I != E; ++I)
757 for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end();
759 if (BBI->getType() != Type::VoidTy)
760 RankMap[BBI] = Rank++;
764 // PropagateBranchInfo - When this method is invoked, we need to propagate
765 // information derived from the branch condition into the true and false
766 // branches of BI. Since we know that there aren't any critical edges in the
767 // flow graph, this can proceed unconditionally.
769 void CEE::PropagateBranchInfo(BranchInst *BI) {
770 assert(BI->isConditional() && "Must be a conditional branch!");
772 // Propagate information into the true block...
774 PropagateEquality(BI->getCondition(), ConstantBool::True,
775 getRegionInfo(BI->getSuccessor(0)));
777 // Propagate information into the false block...
779 PropagateEquality(BI->getCondition(), ConstantBool::False,
780 getRegionInfo(BI->getSuccessor(1)));
784 // PropagateEquality - If we discover that two values are equal to each other in
785 // a specified region, propagate this knowledge recursively.
787 void CEE::PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI) {
788 if (Op0 == Op1) return; // Gee whiz. Are these really equal each other?
790 if (isa<Constant>(Op0)) // Make sure the constant is always Op1
793 // Make sure we don't already know these are equal, to avoid infinite loops...
794 ValueInfo &VI = RI.getValueInfo(Op0);
796 // Get information about the known relationship between Op0 & Op1
797 Relation &KnownRelation = VI.getRelation(Op1);
799 // If we already know they're equal, don't reprocess...
800 if (KnownRelation.getRelation() == Instruction::SetEQ)
803 // If this is boolean, check to see if one of the operands is a constant. If
804 // it's a constant, then see if the other one is one of a setcc instruction,
805 // an AND, OR, or XOR instruction.
807 if (ConstantBool *CB = dyn_cast<ConstantBool>(Op1)) {
809 if (Instruction *Inst = dyn_cast<Instruction>(Op0)) {
810 // If we know that this instruction is an AND instruction, and the result
811 // is true, this means that both operands to the OR are known to be true
814 if (CB->getValue() && Inst->getOpcode() == Instruction::And) {
815 PropagateEquality(Inst->getOperand(0), CB, RI);
816 PropagateEquality(Inst->getOperand(1), CB, RI);
819 // If we know that this instruction is an OR instruction, and the result
820 // is false, this means that both operands to the OR are know to be false
823 if (!CB->getValue() && Inst->getOpcode() == Instruction::Or) {
824 PropagateEquality(Inst->getOperand(0), CB, RI);
825 PropagateEquality(Inst->getOperand(1), CB, RI);
828 // If we know that this instruction is a NOT instruction, we know that the
829 // operand is known to be the inverse of whatever the current value is.
831 if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(Inst))
832 if (BinaryOperator::isNot(BOp))
833 PropagateEquality(BinaryOperator::getNotArgument(BOp),
834 ConstantBool::get(!CB->getValue()), RI);
836 // If we know the value of a SetCC instruction, propagate the information
837 // about the relation into this region as well.
839 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Inst)) {
840 if (CB->getValue()) { // If we know the condition is true...
841 // Propagate info about the LHS to the RHS & RHS to LHS
842 PropagateRelation(SCI->getOpcode(), SCI->getOperand(0),
843 SCI->getOperand(1), RI);
844 PropagateRelation(SCI->getSwappedCondition(),
845 SCI->getOperand(1), SCI->getOperand(0), RI);
847 } else { // If we know the condition is false...
848 // We know the opposite of the condition is true...
849 Instruction::BinaryOps C = SCI->getInverseCondition();
851 PropagateRelation(C, SCI->getOperand(0), SCI->getOperand(1), RI);
852 PropagateRelation(SetCondInst::getSwappedCondition(C),
853 SCI->getOperand(1), SCI->getOperand(0), RI);
859 // Propagate information about Op0 to Op1 & visa versa
860 PropagateRelation(Instruction::SetEQ, Op0, Op1, RI);
861 PropagateRelation(Instruction::SetEQ, Op1, Op0, RI);
865 // PropagateRelation - We know that the specified relation is true in all of the
866 // blocks in the specified region. Propagate the information about Op0 and
867 // anything derived from it into this region.
869 void CEE::PropagateRelation(Instruction::BinaryOps Opcode, Value *Op0,
870 Value *Op1, RegionInfo &RI) {
871 assert(Op0->getType() == Op1->getType() && "Equal types expected!");
873 // Constants are already pretty well understood. We will apply information
874 // about the constant to Op1 in another call to PropagateRelation.
876 if (isa<Constant>(Op0)) return;
878 // Get the region information for this block to update...
879 ValueInfo &VI = RI.getValueInfo(Op0);
881 // Get information about the known relationship between Op0 & Op1
882 Relation &Op1R = VI.getRelation(Op1);
884 // Quick bailout for common case if we are reprocessing an instruction...
885 if (Op1R.getRelation() == Opcode)
888 // If we already have information that contradicts the current information we
889 // are propagating, ignore this info. Something bad must have happened!
891 if (Op1R.contradicts(Opcode, VI)) {
892 Op1R.contradicts(Opcode, VI);
893 std::cerr << "Contradiction found for opcode: "
894 << Instruction::getOpcodeName(Opcode) << "\n";
895 Op1R.print(std::cerr);
899 // If the information propogted is new, then we want process the uses of this
900 // instruction to propagate the information down to them.
902 if (Op1R.incorporate(Opcode, VI))
903 UpdateUsersOfValue(Op0, RI);
907 // UpdateUsersOfValue - The information about V in this region has been updated.
908 // Propagate this to all consumers of the value.
910 void CEE::UpdateUsersOfValue(Value *V, RegionInfo &RI) {
911 for (Value::use_iterator I = V->use_begin(), E = V->use_end();
913 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
914 // If this is an instruction using a value that we know something about,
915 // try to propagate information to the value produced by the
916 // instruction. We can only do this if it is an instruction we can
917 // propagate information for (a setcc for example), and we only WANT to
918 // do this if the instruction dominates this region.
920 // If the instruction doesn't dominate this region, then it cannot be
921 // used in this region and we don't care about it. If the instruction
922 // is IN this region, then we will simplify the instruction before we
923 // get to uses of it anyway, so there is no reason to bother with it
924 // here. This check is also effectively checking to make sure that Inst
925 // is in the same function as our region (in case V is a global f.e.).
927 if (DS->properlyDominates(Inst->getParent(), RI.getEntryBlock()))
928 IncorporateInstruction(Inst, RI);
932 // IncorporateInstruction - We just updated the information about one of the
933 // operands to the specified instruction. Update the information about the
934 // value produced by this instruction
936 void CEE::IncorporateInstruction(Instruction *Inst, RegionInfo &RI) {
937 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Inst)) {
938 // See if we can figure out a result for this instruction...
939 Relation::KnownResult Result = getSetCCResult(SCI, RI);
940 if (Result != Relation::Unknown) {
941 PropagateEquality(SCI, Result ? ConstantBool::True : ConstantBool::False,
948 // ComputeReplacements - Some values are known to be equal to other values in a
949 // region. For example if there is a comparison of equality between a variable
950 // X and a constant C, we can replace all uses of X with C in the region we are
951 // interested in. We generalize this replacement to replace variables with
952 // other variables if they are equal and there is a variable with lower rank
953 // than the current one. This offers a canonicalizing property that exposes
954 // more redundancies for later transformations to take advantage of.
956 void CEE::ComputeReplacements(RegionInfo &RI) {
957 // Loop over all of the values in the region info map...
958 for (RegionInfo::iterator I = RI.begin(), E = RI.end(); I != E; ++I) {
959 ValueInfo &VI = I->second;
961 // If we know that this value is a particular constant, set Replacement to
963 Value *Replacement = VI.getBounds().getSingleElement();
965 // If this value is not known to be some constant, figure out the lowest
966 // rank value that it is known to be equal to (if anything).
968 if (Replacement == 0) {
969 // Find out if there are any equality relationships with values of lower
970 // rank than VI itself...
971 unsigned MinRank = getRank(I->first);
973 // Loop over the relationships known about Op0.
974 const std::vector<Relation> &Relationships = VI.getRelationships();
975 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
976 if (Relationships[i].getRelation() == Instruction::SetEQ) {
977 unsigned R = getRank(Relationships[i].getValue());
980 Replacement = Relationships[i].getValue();
985 // If we found something to replace this value with, keep track of it.
987 VI.setReplacement(Replacement);
991 // SimplifyBasicBlock - Given information about values in region RI, simplify
992 // the instructions in the specified basic block.
994 bool CEE::SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI) {
995 bool Changed = false;
996 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ) {
997 Instruction *Inst = I++;
999 // Convert instruction arguments to canonical forms...
1000 Changed |= SimplifyInstruction(Inst, RI);
1002 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Inst)) {
1003 // Try to simplify a setcc instruction based on inherited information
1004 Relation::KnownResult Result = getSetCCResult(SCI, RI);
1005 if (Result != Relation::Unknown) {
1006 DEBUG(std::cerr << "Replacing setcc with " << Result
1007 << " constant: " << SCI);
1009 SCI->replaceAllUsesWith(ConstantBool::get((bool)Result));
1010 // The instruction is now dead, remove it from the program.
1011 SCI->getParent()->getInstList().erase(SCI);
1021 // SimplifyInstruction - Inspect the operands of the instruction, converting
1022 // them to their canonical form if possible. This takes care of, for example,
1023 // replacing a value 'X' with a constant 'C' if the instruction in question is
1024 // dominated by a true seteq 'X', 'C'.
1026 bool CEE::SimplifyInstruction(Instruction *I, const RegionInfo &RI) {
1027 bool Changed = false;
1029 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1030 if (const ValueInfo *VI = RI.requestValueInfo(I->getOperand(i)))
1031 if (Value *Repl = VI->getReplacement()) {
1032 // If we know if a replacement with lower rank than Op0, make the
1034 DEBUG(std::cerr << "In Inst: " << I << " Replacing operand #" << i
1035 << " with " << Repl << "\n");
1036 I->setOperand(i, Repl);
1045 // getSetCCResult - Try to simplify a setcc instruction based on information
1046 // inherited from a dominating setcc instruction. V is one of the operands to
1047 // the setcc instruction, and VI is the set of information known about it. We
1048 // take two cases into consideration here. If the comparison is against a
1049 // constant value, we can use the constant range to see if the comparison is
1050 // possible to succeed. If it is not a comparison against a constant, we check
1051 // to see if there is a known relationship between the two values. If so, we
1052 // may be able to eliminate the check.
1054 Relation::KnownResult CEE::getSetCCResult(SetCondInst *SCI,
1055 const RegionInfo &RI) {
1056 Value *Op0 = SCI->getOperand(0), *Op1 = SCI->getOperand(1);
1057 Instruction::BinaryOps Opcode = SCI->getOpcode();
1059 if (isa<Constant>(Op0)) {
1060 if (isa<Constant>(Op1)) {
1061 if (Constant *Result = ConstantFoldInstruction(SCI)) {
1062 // Wow, this is easy, directly eliminate the SetCondInst.
1063 DEBUG(std::cerr << "Replacing setcc with constant fold: " << SCI);
1064 return cast<ConstantBool>(Result)->getValue()
1065 ? Relation::KnownTrue : Relation::KnownFalse;
1068 // We want to swap this instruction so that operand #0 is the constant.
1069 std::swap(Op0, Op1);
1070 Opcode = SCI->getSwappedCondition();
1074 // Try to figure out what the result of this comparison will be...
1075 Relation::KnownResult Result = Relation::Unknown;
1077 // We have to know something about the relationship to prove anything...
1078 if (const ValueInfo *Op0VI = RI.requestValueInfo(Op0)) {
1080 // At this point, we know that if we have a constant argument that it is in
1081 // Op1. Check to see if we know anything about comparing value with a
1082 // constant, and if we can use this info to fold the setcc.
1084 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(Op1)) {
1085 // Check to see if we already know the result of this comparison...
1086 ConstantRange R = ConstantRange(Opcode, C);
1087 ConstantRange Int = R.intersectWith(Op0VI->getBounds());
1089 // If the intersection of the two ranges is empty, then the condition
1090 // could never be true!
1092 if (Int.isEmptySet()) {
1093 Result = Relation::KnownFalse;
1095 // Otherwise, if VI.getBounds() (the possible values) is a subset of R
1096 // (the allowed values) then we know that the condition must always be
1099 } else if (Int == Op0VI->getBounds()) {
1100 Result = Relation::KnownTrue;
1103 // If we are here, we know that the second argument is not a constant
1104 // integral. See if we know anything about Op0 & Op1 that allows us to
1105 // fold this anyway.
1107 // Do we have value information about Op0 and a relation to Op1?
1108 if (const Relation *Op2R = Op0VI->requestRelation(Op1))
1109 Result = Op2R->getImpliedResult(Opcode);
1115 //===----------------------------------------------------------------------===//
1116 // Relation Implementation
1117 //===----------------------------------------------------------------------===//
1119 // CheckCondition - Return true if the specified condition is false. Bound may
1121 static bool CheckCondition(Constant *Bound, Constant *C,
1122 Instruction::BinaryOps BO) {
1123 assert(C != 0 && "C is not specified!");
1124 if (Bound == 0) return false;
1128 default: assert(0 && "Unknown Condition code!");
1129 case Instruction::SetEQ: Val = *Bound == *C; break;
1130 case Instruction::SetNE: Val = *Bound != *C; break;
1131 case Instruction::SetLT: Val = *Bound < *C; break;
1132 case Instruction::SetGT: Val = *Bound > *C; break;
1133 case Instruction::SetLE: Val = *Bound <= *C; break;
1134 case Instruction::SetGE: Val = *Bound >= *C; break;
1137 // ConstantHandling code may not succeed in the comparison...
1138 if (Val == 0) return false;
1139 return !Val->getValue(); // Return true if the condition is false...
1142 // contradicts - Return true if the relationship specified by the operand
1143 // contradicts already known information.
1145 bool Relation::contradicts(Instruction::BinaryOps Op,
1146 const ValueInfo &VI) const {
1147 assert (Op != Instruction::Add && "Invalid relation argument!");
1149 // If this is a relationship with a constant, make sure that this relationship
1150 // does not contradict properties known about the bounds of the constant.
1152 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(Val))
1153 if (ConstantRange(Op, C).intersectWith(VI.getBounds()).isEmptySet())
1157 default: assert(0 && "Unknown Relationship code!");
1158 case Instruction::Add: return false; // Nothing known, nothing contradicts
1159 case Instruction::SetEQ:
1160 return Op == Instruction::SetLT || Op == Instruction::SetGT ||
1161 Op == Instruction::SetNE;
1162 case Instruction::SetNE: return Op == Instruction::SetEQ;
1163 case Instruction::SetLE: return Op == Instruction::SetGT;
1164 case Instruction::SetGE: return Op == Instruction::SetLT;
1165 case Instruction::SetLT:
1166 return Op == Instruction::SetEQ || Op == Instruction::SetGT ||
1167 Op == Instruction::SetGE;
1168 case Instruction::SetGT:
1169 return Op == Instruction::SetEQ || Op == Instruction::SetLT ||
1170 Op == Instruction::SetLE;
1174 // incorporate - Incorporate information in the argument into this relation
1175 // entry. This assumes that the information doesn't contradict itself. If any
1176 // new information is gained, true is returned, otherwise false is returned to
1177 // indicate that nothing was updated.
1179 bool Relation::incorporate(Instruction::BinaryOps Op, ValueInfo &VI) {
1180 assert(!contradicts(Op, VI) &&
1181 "Cannot incorporate contradictory information!");
1183 // If this is a relationship with a constant, make sure that we update the
1184 // range that is possible for the value to have...
1186 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(Val))
1187 VI.getBounds() = ConstantRange(Op, C).intersectWith(VI.getBounds());
1190 default: assert(0 && "Unknown prior value!");
1191 case Instruction::Add: Rel = Op; return true;
1192 case Instruction::SetEQ: return false; // Nothing is more precise
1193 case Instruction::SetNE: return false; // Nothing is more precise
1194 case Instruction::SetLT: return false; // Nothing is more precise
1195 case Instruction::SetGT: return false; // Nothing is more precise
1196 case Instruction::SetLE:
1197 if (Op == Instruction::SetEQ || Op == Instruction::SetLT) {
1200 } else if (Op == Instruction::SetNE) {
1201 Rel = Instruction::SetLT;
1205 case Instruction::SetGE: return Op == Instruction::SetLT;
1206 if (Op == Instruction::SetEQ || Op == Instruction::SetGT) {
1209 } else if (Op == Instruction::SetNE) {
1210 Rel = Instruction::SetGT;
1217 // getImpliedResult - If this relationship between two values implies that
1218 // the specified relationship is true or false, return that. If we cannot
1219 // determine the result required, return Unknown.
1221 Relation::KnownResult
1222 Relation::getImpliedResult(Instruction::BinaryOps Op) const {
1223 if (Rel == Op) return KnownTrue;
1224 if (Rel == SetCondInst::getInverseCondition(Op)) return KnownFalse;
1227 default: assert(0 && "Unknown prior value!");
1228 case Instruction::SetEQ:
1229 if (Op == Instruction::SetLE || Op == Instruction::SetGE) return KnownTrue;
1230 if (Op == Instruction::SetLT || Op == Instruction::SetGT) return KnownFalse;
1232 case Instruction::SetLT:
1233 if (Op == Instruction::SetNE || Op == Instruction::SetLE) return KnownTrue;
1234 if (Op == Instruction::SetEQ) return KnownFalse;
1236 case Instruction::SetGT:
1237 if (Op == Instruction::SetNE || Op == Instruction::SetGE) return KnownTrue;
1238 if (Op == Instruction::SetEQ) return KnownFalse;
1240 case Instruction::SetNE:
1241 case Instruction::SetLE:
1242 case Instruction::SetGE:
1243 case Instruction::Add:
1250 //===----------------------------------------------------------------------===//
1251 // Printing Support...
1252 //===----------------------------------------------------------------------===//
1254 // print - Implement the standard print form to print out analysis information.
1255 void CEE::print(std::ostream &O, const Module *M) const {
1256 O << "\nPrinting Correlated Expression Info:\n";
1257 for (std::map<BasicBlock*, RegionInfo>::const_iterator I =
1258 RegionInfoMap.begin(), E = RegionInfoMap.end(); I != E; ++I)
1262 // print - Output information about this region...
1263 void RegionInfo::print(std::ostream &OS) const {
1264 if (ValueMap.empty()) return;
1266 OS << " RegionInfo for basic block: " << BB->getName() << "\n";
1267 for (std::map<Value*, ValueInfo>::const_iterator
1268 I = ValueMap.begin(), E = ValueMap.end(); I != E; ++I)
1269 I->second.print(OS, I->first);
1273 // print - Output information about this value relation...
1274 void ValueInfo::print(std::ostream &OS, Value *V) const {
1275 if (Relationships.empty()) return;
1278 OS << " ValueInfo for: ";
1279 WriteAsOperand(OS, V);
1281 OS << "\n Bounds = " << Bounds << "\n";
1283 OS << " Replacement = ";
1284 WriteAsOperand(OS, Replacement);
1287 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
1288 Relationships[i].print(OS);
1291 // print - Output this relation to the specified stream
1292 void Relation::print(std::ostream &OS) const {
1295 default: OS << "*UNKNOWN*"; break;
1296 case Instruction::SetEQ: OS << "== "; break;
1297 case Instruction::SetNE: OS << "!= "; break;
1298 case Instruction::SetLT: OS << "< "; break;
1299 case Instruction::SetGT: OS << "> "; break;
1300 case Instruction::SetLE: OS << "<= "; break;
1301 case Instruction::SetGE: OS << ">= "; break;
1304 WriteAsOperand(OS, Val);
1308 // Don't inline these methods or else we won't be able to call them from GDB!
1309 void Relation::dump() const { print(std::cerr); }
1310 void ValueInfo::dump() const { print(std::cerr, 0); }
1311 void RegionInfo::dump() const { print(std::cerr); }