1 //===- CorrelatedExprs.cpp - Pass to detect and eliminated c.e.'s ---------===//
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 // Correlated Expression Elimination propagates information from conditional
11 // branches to blocks dominated by destinations of the branch. It propagates
12 // information from the condition check itself into the body of the branch,
13 // allowing transformations like these for example:
16 // ... 4*i; // constant propagation
20 // X = M-N; // = M-M == 0;
22 // This is called Correlated Expression Elimination because we eliminate or
23 // simplify expressions that are correlated with the direction of a branch. In
24 // this way we use static information to give us some information about the
25 // dynamic value of a variable.
27 //===----------------------------------------------------------------------===//
29 #include "llvm/Transforms/Scalar.h"
30 #include "llvm/Constants.h"
31 #include "llvm/Pass.h"
32 #include "llvm/Function.h"
33 #include "llvm/Instructions.h"
34 #include "llvm/Type.h"
35 #include "llvm/Analysis/Dominators.h"
36 #include "llvm/Assembly/Writer.h"
37 #include "llvm/Transforms/Utils/Local.h"
38 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
39 #include "llvm/Support/ConstantRange.h"
40 #include "llvm/Support/CFG.h"
41 #include "llvm/Support/Debug.h"
42 #include "llvm/ADT/PostOrderIterator.h"
43 #include "llvm/ADT/Statistic.h"
48 Statistic NumSetCCRemoved("cee", "Number of setcc instruction eliminated");
49 Statistic NumOperandsCann("cee", "Number of operands canonicalized");
50 Statistic BranchRevectors("cee", "Number of branches revectored");
54 Value *Val; // Relation to what value?
55 Instruction::BinaryOps Rel; // SetCC relation, or Add if no information
57 Relation(Value *V) : Val(V), Rel(Instruction::Add) {}
58 bool operator<(const Relation &R) const { return Val < R.Val; }
59 Value *getValue() const { return Val; }
60 Instruction::BinaryOps getRelation() const { return Rel; }
62 // contradicts - Return true if the relationship specified by the operand
63 // contradicts already known information.
65 bool contradicts(Instruction::BinaryOps Rel, const ValueInfo &VI) const;
67 // incorporate - Incorporate information in the argument into this relation
68 // entry. This assumes that the information doesn't contradict itself. If
69 // any new information is gained, true is returned, otherwise false is
70 // returned to indicate that nothing was updated.
72 bool incorporate(Instruction::BinaryOps Rel, ValueInfo &VI);
74 // KnownResult - Whether or not this condition determines the result of a
75 // setcc in the program. False & True are intentionally 0 & 1 so we can
76 // convert to bool by casting after checking for unknown.
78 enum KnownResult { KnownFalse = 0, KnownTrue = 1, Unknown = 2 };
80 // getImpliedResult - If this relationship between two values implies that
81 // the specified relationship is true or false, return that. If we cannot
82 // determine the result required, return Unknown.
84 KnownResult getImpliedResult(Instruction::BinaryOps Rel) const;
86 // print - Output this relation to the specified stream
87 void print(std::ostream &OS) const;
92 // ValueInfo - One instance of this record exists for every value with
93 // relationships between other values. It keeps track of all of the
94 // relationships to other values in the program (specified with Relation) that
95 // are known to be valid in a region.
98 // RelationShips - this value is know to have the specified relationships to
99 // other values. There can only be one entry per value, and this list is
100 // kept sorted by the Val field.
101 std::vector<Relation> Relationships;
103 // If information about this value is known or propagated from constant
104 // expressions, this range contains the possible values this value may hold.
105 ConstantRange Bounds;
107 // If we find that this value is equal to another value that has a lower
108 // rank, this value is used as it's replacement.
112 ValueInfo(const Type *Ty)
113 : Bounds(Ty->isIntegral() ? Ty : Type::IntTy), Replacement(0) {}
115 // getBounds() - Return the constant bounds of the value...
116 const ConstantRange &getBounds() const { return Bounds; }
117 ConstantRange &getBounds() { return Bounds; }
119 const std::vector<Relation> &getRelationships() { return Relationships; }
121 // getReplacement - Return the value this value is to be replaced with if it
122 // exists, otherwise return null.
124 Value *getReplacement() const { return Replacement; }
126 // setReplacement - Used by the replacement calculation pass to figure out
127 // what to replace this value with, if anything.
129 void setReplacement(Value *Repl) { Replacement = Repl; }
131 // getRelation - return the relationship entry for the specified value.
132 // This can invalidate references to other Relations, so use it carefully.
134 Relation &getRelation(Value *V) {
135 // Binary search for V's entry...
136 std::vector<Relation>::iterator I =
137 std::lower_bound(Relationships.begin(), Relationships.end(),
140 // If we found the entry, return it...
141 if (I != Relationships.end() && I->getValue() == V)
144 // Insert and return the new relationship...
145 return *Relationships.insert(I, V);
148 const Relation *requestRelation(Value *V) const {
149 // Binary search for V's entry...
150 std::vector<Relation>::const_iterator I =
151 std::lower_bound(Relationships.begin(), Relationships.end(),
153 if (I != Relationships.end() && I->getValue() == V)
158 // print - Output information about this value relation...
159 void print(std::ostream &OS, Value *V) const;
163 // RegionInfo - Keeps track of all of the value relationships for a region. A
164 // region is the are dominated by a basic block. RegionInfo's keep track of
165 // the RegionInfo for their dominator, because anything known in a dominator
166 // is known to be true in a dominated block as well.
171 // ValueMap - Tracks the ValueInformation known for this region
172 typedef std::map<Value*, ValueInfo> ValueMapTy;
175 RegionInfo(BasicBlock *bb) : BB(bb) {}
177 // getEntryBlock - Return the block that dominates all of the members of
179 BasicBlock *getEntryBlock() const { return BB; }
181 // empty - return true if this region has no information known about it.
182 bool empty() const { return ValueMap.empty(); }
184 const RegionInfo &operator=(const RegionInfo &RI) {
185 ValueMap = RI.ValueMap;
189 // print - Output information about this region...
190 void print(std::ostream &OS) const;
193 // Allow external access.
194 typedef ValueMapTy::iterator iterator;
195 iterator begin() { return ValueMap.begin(); }
196 iterator end() { return ValueMap.end(); }
198 ValueInfo &getValueInfo(Value *V) {
199 ValueMapTy::iterator I = ValueMap.lower_bound(V);
200 if (I != ValueMap.end() && I->first == V) return I->second;
201 return ValueMap.insert(I, std::make_pair(V, V->getType()))->second;
204 const ValueInfo *requestValueInfo(Value *V) const {
205 ValueMapTy::const_iterator I = ValueMap.find(V);
206 if (I != ValueMap.end()) return &I->second;
210 /// removeValueInfo - Remove anything known about V from our records. This
211 /// works whether or not we know anything about V.
213 void removeValueInfo(Value *V) {
218 /// CEE - Correlated Expression Elimination
219 class CEE : public FunctionPass {
220 std::map<Value*, unsigned> RankMap;
221 std::map<BasicBlock*, RegionInfo> RegionInfoMap;
225 virtual bool runOnFunction(Function &F);
227 // We don't modify the program, so we preserve all analyses
228 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
229 AU.addRequired<ETForest>();
230 AU.addRequired<DominatorTree>();
231 AU.addRequiredID(BreakCriticalEdgesID);
234 // print - Implement the standard print form to print out analysis
236 virtual void print(std::ostream &O, const Module *M) const;
239 RegionInfo &getRegionInfo(BasicBlock *BB) {
240 std::map<BasicBlock*, RegionInfo>::iterator I
241 = RegionInfoMap.lower_bound(BB);
242 if (I != RegionInfoMap.end() && I->first == BB) return I->second;
243 return RegionInfoMap.insert(I, std::make_pair(BB, BB))->second;
246 void BuildRankMap(Function &F);
247 unsigned getRank(Value *V) const {
248 if (isa<Constant>(V)) return 0;
249 std::map<Value*, unsigned>::const_iterator I = RankMap.find(V);
250 if (I != RankMap.end()) return I->second;
251 return 0; // Must be some other global thing
254 bool TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks);
256 bool ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
259 void ForwardSuccessorTo(TerminatorInst *TI, unsigned Succ, BasicBlock *D,
261 void ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
262 BasicBlock *RegionDominator);
263 void CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
264 std::vector<BasicBlock*> &RegionExitBlocks);
265 void InsertRegionExitMerges(PHINode *NewPHI, Instruction *OldVal,
266 const std::vector<BasicBlock*> &RegionExitBlocks);
268 void PropagateBranchInfo(BranchInst *BI);
269 void PropagateSwitchInfo(SwitchInst *SI);
270 void PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI);
271 void PropagateRelation(Instruction::BinaryOps Opcode, Value *Op0,
272 Value *Op1, RegionInfo &RI);
273 void UpdateUsersOfValue(Value *V, RegionInfo &RI);
274 void IncorporateInstruction(Instruction *Inst, RegionInfo &RI);
275 void ComputeReplacements(RegionInfo &RI);
278 // getSetCCResult - Given a setcc instruction, determine if the result is
279 // determined by facts we already know about the region under analysis.
280 // Return KnownTrue, KnownFalse, or Unknown based on what we can determine.
282 Relation::KnownResult getSetCCResult(SetCondInst *SC, const RegionInfo &RI);
285 bool SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI);
286 bool SimplifyInstruction(Instruction *Inst, const RegionInfo &RI);
288 RegisterPass<CEE> X("cee", "Correlated Expression Elimination");
291 FunctionPass *llvm::createCorrelatedExpressionEliminationPass() {
296 bool CEE::runOnFunction(Function &F) {
297 // Build a rank map for the function...
300 // Traverse the dominator tree, computing information for each node in the
301 // tree. Note that our traversal will not even touch unreachable basic
303 EF = &getAnalysis<ETForest>();
304 DT = &getAnalysis<DominatorTree>();
306 std::set<BasicBlock*> VisitedBlocks;
307 bool Changed = TransformRegion(&F.getEntryBlock(), VisitedBlocks);
309 RegionInfoMap.clear();
314 // TransformRegion - Transform the region starting with BB according to the
315 // calculated region information for the block. Transforming the region
316 // involves analyzing any information this block provides to successors,
317 // propagating the information to successors, and finally transforming
320 // This method processes the function in depth first order, which guarantees
321 // that we process the immediate dominator of a block before the block itself.
322 // Because we are passing information from immediate dominators down to
323 // dominatees, we obviously have to process the information source before the
324 // information consumer.
326 bool CEE::TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks){
327 // Prevent infinite recursion...
328 if (VisitedBlocks.count(BB)) return false;
329 VisitedBlocks.insert(BB);
331 // Get the computed region information for this block...
332 RegionInfo &RI = getRegionInfo(BB);
334 // Compute the replacement information for this block...
335 ComputeReplacements(RI);
337 // If debugging, print computed region information...
338 DEBUG(RI.print(*cerr.stream()));
340 // Simplify the contents of this block...
341 bool Changed = SimplifyBasicBlock(*BB, RI);
343 // Get the terminator of this basic block...
344 TerminatorInst *TI = BB->getTerminator();
346 // Loop over all of the blocks that this block is the immediate dominator for.
347 // Because all information known in this region is also known in all of the
348 // blocks that are dominated by this one, we can safely propagate the
349 // information down now.
351 DominatorTree::Node *BBN = (*DT)[BB];
352 if (!RI.empty()) // Time opt: only propagate if we can change something
353 for (unsigned i = 0, e = BBN->getChildren().size(); i != e; ++i) {
354 BasicBlock *Dominated = BBN->getChildren()[i]->getBlock();
355 assert(RegionInfoMap.find(Dominated) == RegionInfoMap.end() &&
356 "RegionInfo should be calculated in dominanace order!");
357 getRegionInfo(Dominated) = RI;
360 // Now that all of our successors have information if they deserve it,
361 // propagate any information our terminator instruction finds to our
363 if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
364 if (BI->isConditional())
365 PropagateBranchInfo(BI);
366 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
367 PropagateSwitchInfo(SI);
370 // If this is a branch to a block outside our region that simply performs
371 // another conditional branch, one whose outcome is known inside of this
372 // region, then vector this outgoing edge directly to the known destination.
374 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
375 while (ForwardCorrelatedEdgeDestination(TI, i, RI)) {
380 // Now that all of our successors have information, recursively process them.
381 for (unsigned i = 0, e = BBN->getChildren().size(); i != e; ++i)
382 Changed |= TransformRegion(BBN->getChildren()[i]->getBlock(),VisitedBlocks);
387 // isBlockSimpleEnoughForCheck to see if the block is simple enough for us to
388 // revector the conditional branch in the bottom of the block, do so now.
390 static bool isBlockSimpleEnough(BasicBlock *BB) {
391 assert(isa<BranchInst>(BB->getTerminator()));
392 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
393 assert(BI->isConditional());
395 // Check the common case first: empty block, or block with just a setcc.
396 if (BB->size() == 1 ||
397 (BB->size() == 2 && &BB->front() == BI->getCondition() &&
398 BI->getCondition()->hasOneUse()))
401 // Check the more complex case now...
402 BasicBlock::iterator I = BB->begin();
404 // FIXME: This should be reenabled once the regression with SIM is fixed!
406 // PHI Nodes are ok, just skip over them...
407 while (isa<PHINode>(*I)) ++I;
410 // Accept the setcc instruction...
411 if (&*I == BI->getCondition())
414 // Nothing else is acceptable here yet. We must not revector... unless we are
415 // at the terminator instruction.
423 bool CEE::ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
425 // If this successor is a simple block not in the current region, which
426 // contains only a conditional branch, we decide if the outcome of the branch
427 // can be determined from information inside of the region. Instead of going
428 // to this block, we can instead go to the destination we know is the right
432 // Check to see if we dominate the block. If so, this block will get the
433 // condition turned to a constant anyway.
435 //if (EF->dominates(RI.getEntryBlock(), BB))
438 BasicBlock *BB = TI->getParent();
440 // Get the destination block of this edge...
441 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
443 // Make sure that the block ends with a conditional branch and is simple
444 // enough for use to be able to revector over.
445 BranchInst *BI = dyn_cast<BranchInst>(OldSucc->getTerminator());
446 if (BI == 0 || !BI->isConditional() || !isBlockSimpleEnough(OldSucc))
449 // We can only forward the branch over the block if the block ends with a
450 // setcc we can determine the outcome for.
452 // FIXME: we can make this more generic. Code below already handles more
454 SetCondInst *SCI = dyn_cast<SetCondInst>(BI->getCondition());
455 if (SCI == 0) return false;
457 // Make a new RegionInfo structure so that we can simulate the effect of the
458 // PHI nodes in the block we are skipping over...
460 RegionInfo NewRI(RI);
462 // Remove value information for all of the values we are simulating... to make
463 // sure we don't have any stale information.
464 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
465 if (I->getType() != Type::VoidTy)
466 NewRI.removeValueInfo(I);
468 // Put the newly discovered information into the RegionInfo...
469 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
470 if (PHINode *PN = dyn_cast<PHINode>(I)) {
471 int OpNum = PN->getBasicBlockIndex(BB);
472 assert(OpNum != -1 && "PHI doesn't have incoming edge for predecessor!?");
473 PropagateEquality(PN, PN->getIncomingValue(OpNum), NewRI);
474 } else if (SetCondInst *SCI = dyn_cast<SetCondInst>(I)) {
475 Relation::KnownResult Res = getSetCCResult(SCI, NewRI);
476 if (Res == Relation::Unknown) return false;
477 PropagateEquality(SCI, ConstantBool::get(Res), NewRI);
479 assert(isa<BranchInst>(*I) && "Unexpected instruction type!");
482 // Compute the facts implied by what we have discovered...
483 ComputeReplacements(NewRI);
485 ValueInfo &PredicateVI = NewRI.getValueInfo(BI->getCondition());
486 if (PredicateVI.getReplacement() &&
487 isa<Constant>(PredicateVI.getReplacement()) &&
488 !isa<GlobalValue>(PredicateVI.getReplacement())) {
489 ConstantBool *CB = cast<ConstantBool>(PredicateVI.getReplacement());
491 // Forward to the successor that corresponds to the branch we will take.
492 ForwardSuccessorTo(TI, SuccNo, BI->getSuccessor(!CB->getValue()), NewRI);
499 static Value *getReplacementOrValue(Value *V, RegionInfo &RI) {
500 if (const ValueInfo *VI = RI.requestValueInfo(V))
501 if (Value *Repl = VI->getReplacement())
506 /// ForwardSuccessorTo - We have found that we can forward successor # 'SuccNo'
507 /// of Terminator 'TI' to the 'Dest' BasicBlock. This method performs the
508 /// mechanics of updating SSA information and revectoring the branch.
510 void CEE::ForwardSuccessorTo(TerminatorInst *TI, unsigned SuccNo,
511 BasicBlock *Dest, RegionInfo &RI) {
512 // If there are any PHI nodes in the Dest BB, we must duplicate the entry
513 // in the PHI node for the old successor to now include an entry from the
514 // current basic block.
516 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
517 BasicBlock *BB = TI->getParent();
519 DOUT << "Forwarding branch in basic block %" << BB->getName()
520 << " from block %" << OldSucc->getName() << " to block %"
521 << Dest->getName() << "\n"
522 << "Before forwarding: " << *BB->getParent();
524 // Because we know that there cannot be critical edges in the flow graph, and
525 // that OldSucc has multiple outgoing edges, this means that Dest cannot have
526 // multiple incoming edges.
529 pred_iterator DPI = pred_begin(Dest); ++DPI;
530 assert(DPI == pred_end(Dest) && "Critical edge found!!");
533 // Loop over any PHI nodes in the destination, eliminating them, because they
534 // may only have one input.
536 while (PHINode *PN = dyn_cast<PHINode>(&Dest->front())) {
537 assert(PN->getNumIncomingValues() == 1 && "Crit edge found!");
538 // Eliminate the PHI node
539 PN->replaceAllUsesWith(PN->getIncomingValue(0));
540 Dest->getInstList().erase(PN);
543 // If there are values defined in the "OldSucc" basic block, we need to insert
544 // PHI nodes in the regions we are dealing with to emulate them. This can
545 // insert dead phi nodes, but it is more trouble to see if they are used than
546 // to just blindly insert them.
548 if (EF->dominates(OldSucc, Dest)) {
549 // RegionExitBlocks - Find all of the blocks that are not dominated by Dest,
550 // but have predecessors that are. Additionally, prune down the set to only
551 // include blocks that are dominated by OldSucc as well.
553 std::vector<BasicBlock*> RegionExitBlocks;
554 CalculateRegionExitBlocks(Dest, OldSucc, RegionExitBlocks);
556 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end();
558 if (I->getType() != Type::VoidTy) {
559 // Create and insert the PHI node into the top of Dest.
560 PHINode *NewPN = new PHINode(I->getType(), I->getName()+".fw_merge",
562 // There is definitely an edge from OldSucc... add the edge now
563 NewPN->addIncoming(I, OldSucc);
565 // There is also an edge from BB now, add the edge with the calculated
566 // value from the RI.
567 NewPN->addIncoming(getReplacementOrValue(I, RI), BB);
569 // Make everything in the Dest region use the new PHI node now...
570 ReplaceUsesOfValueInRegion(I, NewPN, Dest);
572 // Make sure that exits out of the region dominated by NewPN get PHI
573 // nodes that merge the values as appropriate.
574 InsertRegionExitMerges(NewPN, I, RegionExitBlocks);
578 // If there were PHI nodes in OldSucc, we need to remove the entry for this
579 // edge from the PHI node, and we need to replace any references to the PHI
580 // node with a new value.
582 for (BasicBlock::iterator I = OldSucc->begin(); isa<PHINode>(I); ) {
583 PHINode *PN = cast<PHINode>(I);
585 // Get the value flowing across the old edge and remove the PHI node entry
586 // for this edge: we are about to remove the edge! Don't remove the PHI
587 // node yet though if this is the last edge into it.
588 Value *EdgeValue = PN->removeIncomingValue(BB, false);
590 // Make sure that anything that used to use PN now refers to EdgeValue
591 ReplaceUsesOfValueInRegion(PN, EdgeValue, Dest);
593 // If there is only one value left coming into the PHI node, replace the PHI
594 // node itself with the one incoming value left.
596 if (PN->getNumIncomingValues() == 1) {
597 assert(PN->getNumIncomingValues() == 1);
598 PN->replaceAllUsesWith(PN->getIncomingValue(0));
599 PN->getParent()->getInstList().erase(PN);
600 I = OldSucc->begin();
601 } else if (PN->getNumIncomingValues() == 0) { // Nuke the PHI
602 // If we removed the last incoming value to this PHI, nuke the PHI node
604 PN->replaceAllUsesWith(Constant::getNullValue(PN->getType()));
605 PN->getParent()->getInstList().erase(PN);
606 I = OldSucc->begin();
608 ++I; // Otherwise, move on to the next PHI node
612 // Actually revector the branch now...
613 TI->setSuccessor(SuccNo, Dest);
615 // If we just introduced a critical edge in the flow graph, make sure to break
617 SplitCriticalEdge(TI, SuccNo, this);
619 // Make sure that we don't introduce critical edges from oldsucc now!
620 for (unsigned i = 0, e = OldSucc->getTerminator()->getNumSuccessors();
622 SplitCriticalEdge(OldSucc->getTerminator(), i, this);
624 // Since we invalidated the CFG, recalculate the dominator set so that it is
625 // useful for later processing!
626 // FIXME: This is much worse than it really should be!
629 DOUT << "After forwarding: " << *BB->getParent();
632 /// ReplaceUsesOfValueInRegion - This method replaces all uses of Orig with uses
633 /// of New. It only affects instructions that are defined in basic blocks that
634 /// are dominated by Head.
636 void CEE::ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
637 BasicBlock *RegionDominator) {
638 assert(Orig != New && "Cannot replace value with itself");
639 std::vector<Instruction*> InstsToChange;
640 std::vector<PHINode*> PHIsToChange;
641 InstsToChange.reserve(Orig->getNumUses());
643 // Loop over instructions adding them to InstsToChange vector, this allows us
644 // an easy way to avoid invalidating the use_iterator at a bad time.
645 for (Value::use_iterator I = Orig->use_begin(), E = Orig->use_end();
647 if (Instruction *User = dyn_cast<Instruction>(*I))
648 if (EF->dominates(RegionDominator, User->getParent()))
649 InstsToChange.push_back(User);
650 else if (PHINode *PN = dyn_cast<PHINode>(User)) {
651 PHIsToChange.push_back(PN);
654 // PHIsToChange contains PHI nodes that use Orig that do not live in blocks
655 // dominated by orig. If the block the value flows in from is dominated by
656 // RegionDominator, then we rewrite the PHI
657 for (unsigned i = 0, e = PHIsToChange.size(); i != e; ++i) {
658 PHINode *PN = PHIsToChange[i];
659 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
660 if (PN->getIncomingValue(j) == Orig &&
661 EF->dominates(RegionDominator, PN->getIncomingBlock(j)))
662 PN->setIncomingValue(j, New);
665 // Loop over the InstsToChange list, replacing all uses of Orig with uses of
666 // New. This list contains all of the instructions in our region that use
668 for (unsigned i = 0, e = InstsToChange.size(); i != e; ++i)
669 if (PHINode *PN = dyn_cast<PHINode>(InstsToChange[i])) {
670 // PHINodes must be handled carefully. If the PHI node itself is in the
671 // region, we have to make sure to only do the replacement for incoming
672 // values that correspond to basic blocks in the region.
673 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
674 if (PN->getIncomingValue(j) == Orig &&
675 EF->dominates(RegionDominator, PN->getIncomingBlock(j)))
676 PN->setIncomingValue(j, New);
679 InstsToChange[i]->replaceUsesOfWith(Orig, New);
683 static void CalcRegionExitBlocks(BasicBlock *Header, BasicBlock *BB,
684 std::set<BasicBlock*> &Visited,
686 std::vector<BasicBlock*> &RegionExitBlocks) {
687 if (Visited.count(BB)) return;
690 if (EF.dominates(Header, BB)) { // Block in the region, recursively traverse
691 for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
692 CalcRegionExitBlocks(Header, *I, Visited, EF, RegionExitBlocks);
694 // Header does not dominate this block, but we have a predecessor that does
695 // dominate us. Add ourself to the list.
696 RegionExitBlocks.push_back(BB);
700 /// CalculateRegionExitBlocks - Find all of the blocks that are not dominated by
701 /// BB, but have predecessors that are. Additionally, prune down the set to
702 /// only include blocks that are dominated by OldSucc as well.
704 void CEE::CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
705 std::vector<BasicBlock*> &RegionExitBlocks){
706 std::set<BasicBlock*> Visited; // Don't infinite loop
708 // Recursively calculate blocks we are interested in...
709 CalcRegionExitBlocks(BB, BB, Visited, *EF, RegionExitBlocks);
711 // Filter out blocks that are not dominated by OldSucc...
712 for (unsigned i = 0; i != RegionExitBlocks.size(); ) {
713 if (EF->dominates(OldSucc, RegionExitBlocks[i]))
714 ++i; // Block is ok, keep it.
716 // Move to end of list...
717 std::swap(RegionExitBlocks[i], RegionExitBlocks.back());
718 RegionExitBlocks.pop_back(); // Nuke the end
723 void CEE::InsertRegionExitMerges(PHINode *BBVal, Instruction *OldVal,
724 const std::vector<BasicBlock*> &RegionExitBlocks) {
725 assert(BBVal->getType() == OldVal->getType() && "Should be derived values!");
726 BasicBlock *BB = BBVal->getParent();
728 // Loop over all of the blocks we have to place PHIs in, doing it.
729 for (unsigned i = 0, e = RegionExitBlocks.size(); i != e; ++i) {
730 BasicBlock *FBlock = RegionExitBlocks[i]; // Block on the frontier
732 // Create the new PHI node
733 PHINode *NewPN = new PHINode(BBVal->getType(),
734 OldVal->getName()+".fw_frontier",
737 // Add an incoming value for every predecessor of the block...
738 for (pred_iterator PI = pred_begin(FBlock), PE = pred_end(FBlock);
740 // If the incoming edge is from the region dominated by BB, use BBVal,
741 // otherwise use OldVal.
742 NewPN->addIncoming(EF->dominates(BB, *PI) ? BBVal : OldVal, *PI);
745 // Now make everyone dominated by this block use this new value!
746 ReplaceUsesOfValueInRegion(OldVal, NewPN, FBlock);
752 // BuildRankMap - This method builds the rank map data structure which gives
753 // each instruction/value in the function a value based on how early it appears
754 // in the function. We give constants and globals rank 0, arguments are
755 // numbered starting at one, and instructions are numbered in reverse post-order
756 // from where the arguments leave off. This gives instructions in loops higher
757 // values than instructions not in loops.
759 void CEE::BuildRankMap(Function &F) {
760 unsigned Rank = 1; // Skip rank zero.
762 // Number the arguments...
763 for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
766 // Number the instructions in reverse post order...
767 ReversePostOrderTraversal<Function*> RPOT(&F);
768 for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
769 E = RPOT.end(); I != E; ++I)
770 for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end();
772 if (BBI->getType() != Type::VoidTy)
773 RankMap[BBI] = Rank++;
777 // PropagateBranchInfo - When this method is invoked, we need to propagate
778 // information derived from the branch condition into the true and false
779 // branches of BI. Since we know that there aren't any critical edges in the
780 // flow graph, this can proceed unconditionally.
782 void CEE::PropagateBranchInfo(BranchInst *BI) {
783 assert(BI->isConditional() && "Must be a conditional branch!");
785 // Propagate information into the true block...
787 PropagateEquality(BI->getCondition(), ConstantBool::getTrue(),
788 getRegionInfo(BI->getSuccessor(0)));
790 // Propagate information into the false block...
792 PropagateEquality(BI->getCondition(), ConstantBool::getFalse(),
793 getRegionInfo(BI->getSuccessor(1)));
797 // PropagateSwitchInfo - We need to propagate the value tested by the
798 // switch statement through each case block.
800 void CEE::PropagateSwitchInfo(SwitchInst *SI) {
801 // Propagate information down each of our non-default case labels. We
802 // don't yet propagate information down the default label, because a
803 // potentially large number of inequality constraints provide less
804 // benefit per unit work than a single equality constraint.
806 Value *cond = SI->getCondition();
807 for (unsigned i = 1; i < SI->getNumSuccessors(); ++i)
808 PropagateEquality(cond, SI->getSuccessorValue(i),
809 getRegionInfo(SI->getSuccessor(i)));
813 // PropagateEquality - If we discover that two values are equal to each other in
814 // a specified region, propagate this knowledge recursively.
816 void CEE::PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI) {
817 if (Op0 == Op1) return; // Gee whiz. Are these really equal each other?
819 if (isa<Constant>(Op0)) // Make sure the constant is always Op1
822 // Make sure we don't already know these are equal, to avoid infinite loops...
823 ValueInfo &VI = RI.getValueInfo(Op0);
825 // Get information about the known relationship between Op0 & Op1
826 Relation &KnownRelation = VI.getRelation(Op1);
828 // If we already know they're equal, don't reprocess...
829 if (KnownRelation.getRelation() == Instruction::SetEQ)
832 // If this is boolean, check to see if one of the operands is a constant. If
833 // it's a constant, then see if the other one is one of a setcc instruction,
834 // an AND, OR, or XOR instruction.
836 if (ConstantBool *CB = dyn_cast<ConstantBool>(Op1)) {
838 if (Instruction *Inst = dyn_cast<Instruction>(Op0)) {
839 // If we know that this instruction is an AND instruction, and the result
840 // is true, this means that both operands to the OR are known to be true
843 if (CB->getValue() && Inst->getOpcode() == Instruction::And) {
844 PropagateEquality(Inst->getOperand(0), CB, RI);
845 PropagateEquality(Inst->getOperand(1), CB, RI);
848 // If we know that this instruction is an OR instruction, and the result
849 // is false, this means that both operands to the OR are know to be false
852 if (!CB->getValue() && Inst->getOpcode() == Instruction::Or) {
853 PropagateEquality(Inst->getOperand(0), CB, RI);
854 PropagateEquality(Inst->getOperand(1), CB, RI);
857 // If we know that this instruction is a NOT instruction, we know that the
858 // operand is known to be the inverse of whatever the current value is.
860 if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(Inst))
861 if (BinaryOperator::isNot(BOp))
862 PropagateEquality(BinaryOperator::getNotArgument(BOp),
863 ConstantBool::get(!CB->getValue()), RI);
865 // If we know the value of a SetCC instruction, propagate the information
866 // about the relation into this region as well.
868 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Inst)) {
869 if (CB->getValue()) { // If we know the condition is true...
870 // Propagate info about the LHS to the RHS & RHS to LHS
871 PropagateRelation(SCI->getOpcode(), SCI->getOperand(0),
872 SCI->getOperand(1), RI);
873 PropagateRelation(SCI->getSwappedCondition(),
874 SCI->getOperand(1), SCI->getOperand(0), RI);
876 } else { // If we know the condition is false...
877 // We know the opposite of the condition is true...
878 Instruction::BinaryOps C = SCI->getInverseCondition();
880 PropagateRelation(C, SCI->getOperand(0), SCI->getOperand(1), RI);
881 PropagateRelation(SetCondInst::getSwappedCondition(C),
882 SCI->getOperand(1), SCI->getOperand(0), RI);
888 // Propagate information about Op0 to Op1 & visa versa
889 PropagateRelation(Instruction::SetEQ, Op0, Op1, RI);
890 PropagateRelation(Instruction::SetEQ, Op1, Op0, RI);
894 // PropagateRelation - We know that the specified relation is true in all of the
895 // blocks in the specified region. Propagate the information about Op0 and
896 // anything derived from it into this region.
898 void CEE::PropagateRelation(Instruction::BinaryOps Opcode, Value *Op0,
899 Value *Op1, RegionInfo &RI) {
900 assert(Op0->getType() == Op1->getType() && "Equal types expected!");
902 // Constants are already pretty well understood. We will apply information
903 // about the constant to Op1 in another call to PropagateRelation.
905 if (isa<Constant>(Op0)) return;
907 // Get the region information for this block to update...
908 ValueInfo &VI = RI.getValueInfo(Op0);
910 // Get information about the known relationship between Op0 & Op1
911 Relation &Op1R = VI.getRelation(Op1);
913 // Quick bailout for common case if we are reprocessing an instruction...
914 if (Op1R.getRelation() == Opcode)
917 // If we already have information that contradicts the current information we
918 // are propagating, ignore this info. Something bad must have happened!
920 if (Op1R.contradicts(Opcode, VI)) {
921 Op1R.contradicts(Opcode, VI);
922 cerr << "Contradiction found for opcode: "
923 << Instruction::getOpcodeName(Opcode) << "\n";
924 Op1R.print(*cerr.stream());
928 // If the information propagated is new, then we want process the uses of this
929 // instruction to propagate the information down to them.
931 if (Op1R.incorporate(Opcode, VI))
932 UpdateUsersOfValue(Op0, RI);
936 // UpdateUsersOfValue - The information about V in this region has been updated.
937 // Propagate this to all consumers of the value.
939 void CEE::UpdateUsersOfValue(Value *V, RegionInfo &RI) {
940 for (Value::use_iterator I = V->use_begin(), E = V->use_end();
942 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
943 // If this is an instruction using a value that we know something about,
944 // try to propagate information to the value produced by the
945 // instruction. We can only do this if it is an instruction we can
946 // propagate information for (a setcc for example), and we only WANT to
947 // do this if the instruction dominates this region.
949 // If the instruction doesn't dominate this region, then it cannot be
950 // used in this region and we don't care about it. If the instruction
951 // is IN this region, then we will simplify the instruction before we
952 // get to uses of it anyway, so there is no reason to bother with it
953 // here. This check is also effectively checking to make sure that Inst
954 // is in the same function as our region (in case V is a global f.e.).
956 if (EF->properlyDominates(Inst->getParent(), RI.getEntryBlock()))
957 IncorporateInstruction(Inst, RI);
961 // IncorporateInstruction - We just updated the information about one of the
962 // operands to the specified instruction. Update the information about the
963 // value produced by this instruction
965 void CEE::IncorporateInstruction(Instruction *Inst, RegionInfo &RI) {
966 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Inst)) {
967 // See if we can figure out a result for this instruction...
968 Relation::KnownResult Result = getSetCCResult(SCI, RI);
969 if (Result != Relation::Unknown) {
970 PropagateEquality(SCI, ConstantBool::get(Result != 0), RI);
976 // ComputeReplacements - Some values are known to be equal to other values in a
977 // region. For example if there is a comparison of equality between a variable
978 // X and a constant C, we can replace all uses of X with C in the region we are
979 // interested in. We generalize this replacement to replace variables with
980 // other variables if they are equal and there is a variable with lower rank
981 // than the current one. This offers a canonicalizing property that exposes
982 // more redundancies for later transformations to take advantage of.
984 void CEE::ComputeReplacements(RegionInfo &RI) {
985 // Loop over all of the values in the region info map...
986 for (RegionInfo::iterator I = RI.begin(), E = RI.end(); I != E; ++I) {
987 ValueInfo &VI = I->second;
989 // If we know that this value is a particular constant, set Replacement to
991 Value *Replacement = VI.getBounds().getSingleElement();
993 // If this value is not known to be some constant, figure out the lowest
994 // rank value that it is known to be equal to (if anything).
996 if (Replacement == 0) {
997 // Find out if there are any equality relationships with values of lower
998 // rank than VI itself...
999 unsigned MinRank = getRank(I->first);
1001 // Loop over the relationships known about Op0.
1002 const std::vector<Relation> &Relationships = VI.getRelationships();
1003 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
1004 if (Relationships[i].getRelation() == Instruction::SetEQ) {
1005 unsigned R = getRank(Relationships[i].getValue());
1008 Replacement = Relationships[i].getValue();
1013 // If we found something to replace this value with, keep track of it.
1015 VI.setReplacement(Replacement);
1019 // SimplifyBasicBlock - Given information about values in region RI, simplify
1020 // the instructions in the specified basic block.
1022 bool CEE::SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI) {
1023 bool Changed = false;
1024 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ) {
1025 Instruction *Inst = I++;
1027 // Convert instruction arguments to canonical forms...
1028 Changed |= SimplifyInstruction(Inst, RI);
1030 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Inst)) {
1031 // Try to simplify a setcc instruction based on inherited information
1032 Relation::KnownResult Result = getSetCCResult(SCI, RI);
1033 if (Result != Relation::Unknown) {
1034 DOUT << "Replacing setcc with " << Result << " constant: " << *SCI;
1036 SCI->replaceAllUsesWith(ConstantBool::get((bool)Result));
1037 // The instruction is now dead, remove it from the program.
1038 SCI->getParent()->getInstList().erase(SCI);
1048 // SimplifyInstruction - Inspect the operands of the instruction, converting
1049 // them to their canonical form if possible. This takes care of, for example,
1050 // replacing a value 'X' with a constant 'C' if the instruction in question is
1051 // dominated by a true seteq 'X', 'C'.
1053 bool CEE::SimplifyInstruction(Instruction *I, const RegionInfo &RI) {
1054 bool Changed = false;
1056 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1057 if (const ValueInfo *VI = RI.requestValueInfo(I->getOperand(i)))
1058 if (Value *Repl = VI->getReplacement()) {
1059 // If we know if a replacement with lower rank than Op0, make the
1061 DOUT << "In Inst: " << *I << " Replacing operand #" << i
1062 << " with " << *Repl << "\n";
1063 I->setOperand(i, Repl);
1072 // getSetCCResult - Try to simplify a setcc instruction based on information
1073 // inherited from a dominating setcc instruction. V is one of the operands to
1074 // the setcc instruction, and VI is the set of information known about it. We
1075 // take two cases into consideration here. If the comparison is against a
1076 // constant value, we can use the constant range to see if the comparison is
1077 // possible to succeed. If it is not a comparison against a constant, we check
1078 // to see if there is a known relationship between the two values. If so, we
1079 // may be able to eliminate the check.
1081 Relation::KnownResult CEE::getSetCCResult(SetCondInst *SCI,
1082 const RegionInfo &RI) {
1083 Value *Op0 = SCI->getOperand(0), *Op1 = SCI->getOperand(1);
1084 Instruction::BinaryOps Opcode = SCI->getOpcode();
1086 if (isa<Constant>(Op0)) {
1087 if (isa<Constant>(Op1)) {
1088 if (Constant *Result = ConstantFoldInstruction(SCI)) {
1089 // Wow, this is easy, directly eliminate the SetCondInst.
1090 DOUT << "Replacing setcc with constant fold: " << *SCI;
1091 return cast<ConstantBool>(Result)->getValue()
1092 ? Relation::KnownTrue : Relation::KnownFalse;
1095 // We want to swap this instruction so that operand #0 is the constant.
1096 std::swap(Op0, Op1);
1097 Opcode = SCI->getSwappedCondition();
1101 // Try to figure out what the result of this comparison will be...
1102 Relation::KnownResult Result = Relation::Unknown;
1104 // We have to know something about the relationship to prove anything...
1105 if (const ValueInfo *Op0VI = RI.requestValueInfo(Op0)) {
1107 // At this point, we know that if we have a constant argument that it is in
1108 // Op1. Check to see if we know anything about comparing value with a
1109 // constant, and if we can use this info to fold the setcc.
1111 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(Op1)) {
1112 // Check to see if we already know the result of this comparison...
1113 ConstantRange R = ConstantRange(Opcode, C);
1114 ConstantRange Int = R.intersectWith(Op0VI->getBounds());
1116 // If the intersection of the two ranges is empty, then the condition
1117 // could never be true!
1119 if (Int.isEmptySet()) {
1120 Result = Relation::KnownFalse;
1122 // Otherwise, if VI.getBounds() (the possible values) is a subset of R
1123 // (the allowed values) then we know that the condition must always be
1126 } else if (Int == Op0VI->getBounds()) {
1127 Result = Relation::KnownTrue;
1130 // If we are here, we know that the second argument is not a constant
1131 // integral. See if we know anything about Op0 & Op1 that allows us to
1132 // fold this anyway.
1134 // Do we have value information about Op0 and a relation to Op1?
1135 if (const Relation *Op2R = Op0VI->requestRelation(Op1))
1136 Result = Op2R->getImpliedResult(Opcode);
1142 //===----------------------------------------------------------------------===//
1143 // Relation Implementation
1144 //===----------------------------------------------------------------------===//
1146 // contradicts - Return true if the relationship specified by the operand
1147 // contradicts already known information.
1149 bool Relation::contradicts(Instruction::BinaryOps Op,
1150 const ValueInfo &VI) const {
1151 assert (Op != Instruction::Add && "Invalid relation argument!");
1153 // If this is a relationship with a constant, make sure that this relationship
1154 // does not contradict properties known about the bounds of the constant.
1156 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(Val))
1157 if (ConstantRange(Op, C).intersectWith(VI.getBounds()).isEmptySet())
1161 default: assert(0 && "Unknown Relationship code!");
1162 case Instruction::Add: return false; // Nothing known, nothing contradicts
1163 case Instruction::SetEQ:
1164 return Op == Instruction::SetLT || Op == Instruction::SetGT ||
1165 Op == Instruction::SetNE;
1166 case Instruction::SetNE: return Op == Instruction::SetEQ;
1167 case Instruction::SetLE: return Op == Instruction::SetGT;
1168 case Instruction::SetGE: return Op == Instruction::SetLT;
1169 case Instruction::SetLT:
1170 return Op == Instruction::SetEQ || Op == Instruction::SetGT ||
1171 Op == Instruction::SetGE;
1172 case Instruction::SetGT:
1173 return Op == Instruction::SetEQ || Op == Instruction::SetLT ||
1174 Op == Instruction::SetLE;
1178 // incorporate - Incorporate information in the argument into this relation
1179 // entry. This assumes that the information doesn't contradict itself. If any
1180 // new information is gained, true is returned, otherwise false is returned to
1181 // indicate that nothing was updated.
1183 bool Relation::incorporate(Instruction::BinaryOps Op, ValueInfo &VI) {
1184 assert(!contradicts(Op, VI) &&
1185 "Cannot incorporate contradictory information!");
1187 // If this is a relationship with a constant, make sure that we update the
1188 // range that is possible for the value to have...
1190 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(Val))
1191 VI.getBounds() = ConstantRange(Op, C).intersectWith(VI.getBounds());
1194 default: assert(0 && "Unknown prior value!");
1195 case Instruction::Add: Rel = Op; return true;
1196 case Instruction::SetEQ: return false; // Nothing is more precise
1197 case Instruction::SetNE: return false; // Nothing is more precise
1198 case Instruction::SetLT: return false; // Nothing is more precise
1199 case Instruction::SetGT: return false; // Nothing is more precise
1200 case Instruction::SetLE:
1201 if (Op == Instruction::SetEQ || Op == Instruction::SetLT) {
1204 } else if (Op == Instruction::SetNE) {
1205 Rel = Instruction::SetLT;
1209 case Instruction::SetGE: return Op == Instruction::SetLT;
1210 if (Op == Instruction::SetEQ || Op == Instruction::SetGT) {
1213 } else if (Op == Instruction::SetNE) {
1214 Rel = Instruction::SetGT;
1221 // getImpliedResult - If this relationship between two values implies that
1222 // the specified relationship is true or false, return that. If we cannot
1223 // determine the result required, return Unknown.
1225 Relation::KnownResult
1226 Relation::getImpliedResult(Instruction::BinaryOps Op) const {
1227 if (Rel == Op) return KnownTrue;
1228 if (Rel == SetCondInst::getInverseCondition(Op)) return KnownFalse;
1231 default: assert(0 && "Unknown prior value!");
1232 case Instruction::SetEQ:
1233 if (Op == Instruction::SetLE || Op == Instruction::SetGE) return KnownTrue;
1234 if (Op == Instruction::SetLT || Op == Instruction::SetGT) return KnownFalse;
1236 case Instruction::SetLT:
1237 if (Op == Instruction::SetNE || Op == Instruction::SetLE) return KnownTrue;
1238 if (Op == Instruction::SetEQ) return KnownFalse;
1240 case Instruction::SetGT:
1241 if (Op == Instruction::SetNE || Op == Instruction::SetGE) return KnownTrue;
1242 if (Op == Instruction::SetEQ) return KnownFalse;
1244 case Instruction::SetNE:
1245 case Instruction::SetLE:
1246 case Instruction::SetGE:
1247 case Instruction::Add:
1254 //===----------------------------------------------------------------------===//
1255 // Printing Support...
1256 //===----------------------------------------------------------------------===//
1258 // print - Implement the standard print form to print out analysis information.
1259 void CEE::print(std::ostream &O, const Module *M) const {
1260 O << "\nPrinting Correlated Expression Info:\n";
1261 for (std::map<BasicBlock*, RegionInfo>::const_iterator I =
1262 RegionInfoMap.begin(), E = RegionInfoMap.end(); I != E; ++I)
1266 // print - Output information about this region...
1267 void RegionInfo::print(std::ostream &OS) const {
1268 if (ValueMap.empty()) return;
1270 OS << " RegionInfo for basic block: " << BB->getName() << "\n";
1271 for (std::map<Value*, ValueInfo>::const_iterator
1272 I = ValueMap.begin(), E = ValueMap.end(); I != E; ++I)
1273 I->second.print(OS, I->first);
1277 // print - Output information about this value relation...
1278 void ValueInfo::print(std::ostream &OS, Value *V) const {
1279 if (Relationships.empty()) return;
1282 OS << " ValueInfo for: ";
1283 WriteAsOperand(OS, V);
1285 OS << "\n Bounds = " << Bounds << "\n";
1287 OS << " Replacement = ";
1288 WriteAsOperand(OS, Replacement);
1291 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
1292 Relationships[i].print(OS);
1295 // print - Output this relation to the specified stream
1296 void Relation::print(std::ostream &OS) const {
1299 default: OS << "*UNKNOWN*"; break;
1300 case Instruction::SetEQ: OS << "== "; break;
1301 case Instruction::SetNE: OS << "!= "; break;
1302 case Instruction::SetLT: OS << "< "; break;
1303 case Instruction::SetGT: OS << "> "; break;
1304 case Instruction::SetLE: OS << "<= "; break;
1305 case Instruction::SetGE: OS << ">= "; break;
1308 WriteAsOperand(OS, Val);
1312 // Don't inline these methods or else we won't be able to call them from GDB!
1313 void Relation::dump() const { print(*cerr.stream()); }
1314 void ValueInfo::dump() const { print(*cerr.stream(), 0); }
1315 void RegionInfo::dump() const { print(*cerr.stream()); }