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(), V);
139 // If we found the entry, return it...
140 if (I != Relationships.end() && I->getValue() == V)
143 // Insert and return the new relationship...
144 return *Relationships.insert(I, V);
147 const Relation *requestRelation(Value *V) const {
148 // Binary search for V's entry...
149 std::vector<Relation>::const_iterator I =
150 std::lower_bound(Relationships.begin(), Relationships.end(), V);
151 if (I != Relationships.end() && I->getValue() == V)
156 // print - Output information about this value relation...
157 void print(std::ostream &OS, Value *V) const;
161 // RegionInfo - Keeps track of all of the value relationships for a region. A
162 // region is the are dominated by a basic block. RegionInfo's keep track of
163 // the RegionInfo for their dominator, because anything known in a dominator
164 // is known to be true in a dominated block as well.
169 // ValueMap - Tracks the ValueInformation known for this region
170 typedef std::map<Value*, ValueInfo> ValueMapTy;
173 RegionInfo(BasicBlock *bb) : BB(bb) {}
175 // getEntryBlock - Return the block that dominates all of the members of
177 BasicBlock *getEntryBlock() const { return BB; }
179 // empty - return true if this region has no information known about it.
180 bool empty() const { return ValueMap.empty(); }
182 const RegionInfo &operator=(const RegionInfo &RI) {
183 ValueMap = RI.ValueMap;
187 // print - Output information about this region...
188 void print(std::ostream &OS) const;
191 // Allow external access.
192 typedef ValueMapTy::iterator iterator;
193 iterator begin() { return ValueMap.begin(); }
194 iterator end() { return ValueMap.end(); }
196 ValueInfo &getValueInfo(Value *V) {
197 ValueMapTy::iterator I = ValueMap.lower_bound(V);
198 if (I != ValueMap.end() && I->first == V) return I->second;
199 return ValueMap.insert(I, std::make_pair(V, V->getType()))->second;
202 const ValueInfo *requestValueInfo(Value *V) const {
203 ValueMapTy::const_iterator I = ValueMap.find(V);
204 if (I != ValueMap.end()) return &I->second;
208 /// removeValueInfo - Remove anything known about V from our records. This
209 /// works whether or not we know anything about V.
211 void removeValueInfo(Value *V) {
216 /// CEE - Correlated Expression Elimination
217 class CEE : public FunctionPass {
218 std::map<Value*, unsigned> RankMap;
219 std::map<BasicBlock*, RegionInfo> RegionInfoMap;
223 virtual bool runOnFunction(Function &F);
225 // We don't modify the program, so we preserve all analyses
226 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
227 AU.addRequired<DominatorSet>();
228 AU.addRequired<DominatorTree>();
229 AU.addRequiredID(BreakCriticalEdgesID);
232 // print - Implement the standard print form to print out analysis
234 virtual void print(std::ostream &O, const Module *M) const;
237 RegionInfo &getRegionInfo(BasicBlock *BB) {
238 std::map<BasicBlock*, RegionInfo>::iterator I
239 = RegionInfoMap.lower_bound(BB);
240 if (I != RegionInfoMap.end() && I->first == BB) return I->second;
241 return RegionInfoMap.insert(I, std::make_pair(BB, BB))->second;
244 void BuildRankMap(Function &F);
245 unsigned getRank(Value *V) const {
246 if (isa<Constant>(V)) return 0;
247 std::map<Value*, unsigned>::const_iterator I = RankMap.find(V);
248 if (I != RankMap.end()) return I->second;
249 return 0; // Must be some other global thing
252 bool TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks);
254 bool ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
257 void ForwardSuccessorTo(TerminatorInst *TI, unsigned Succ, BasicBlock *D,
259 void ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
260 BasicBlock *RegionDominator);
261 void CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
262 std::vector<BasicBlock*> &RegionExitBlocks);
263 void InsertRegionExitMerges(PHINode *NewPHI, Instruction *OldVal,
264 const std::vector<BasicBlock*> &RegionExitBlocks);
266 void PropagateBranchInfo(BranchInst *BI);
267 void PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI);
268 void PropagateRelation(Instruction::BinaryOps Opcode, Value *Op0,
269 Value *Op1, RegionInfo &RI);
270 void UpdateUsersOfValue(Value *V, RegionInfo &RI);
271 void IncorporateInstruction(Instruction *Inst, RegionInfo &RI);
272 void ComputeReplacements(RegionInfo &RI);
275 // getSetCCResult - Given a setcc instruction, determine if the result is
276 // determined by facts we already know about the region under analysis.
277 // Return KnownTrue, KnownFalse, or Unknown based on what we can determine.
279 Relation::KnownResult getSetCCResult(SetCondInst *SC, const RegionInfo &RI);
282 bool SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI);
283 bool SimplifyInstruction(Instruction *Inst, const RegionInfo &RI);
285 RegisterOpt<CEE> X("cee", "Correlated Expression Elimination");
288 FunctionPass *llvm::createCorrelatedExpressionEliminationPass() {
293 bool CEE::runOnFunction(Function &F) {
294 // Build a rank map for the function...
297 // Traverse the dominator tree, computing information for each node in the
298 // tree. Note that our traversal will not even touch unreachable basic
300 DS = &getAnalysis<DominatorSet>();
301 DT = &getAnalysis<DominatorTree>();
303 std::set<BasicBlock*> VisitedBlocks;
304 bool Changed = TransformRegion(&F.getEntryBlock(), VisitedBlocks);
306 RegionInfoMap.clear();
311 // TransformRegion - Transform the region starting with BB according to the
312 // calculated region information for the block. Transforming the region
313 // involves analyzing any information this block provides to successors,
314 // propagating the information to successors, and finally transforming
317 // This method processes the function in depth first order, which guarantees
318 // that we process the immediate dominator of a block before the block itself.
319 // Because we are passing information from immediate dominators down to
320 // dominatees, we obviously have to process the information source before the
321 // information consumer.
323 bool CEE::TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks){
324 // Prevent infinite recursion...
325 if (VisitedBlocks.count(BB)) return false;
326 VisitedBlocks.insert(BB);
328 // Get the computed region information for this block...
329 RegionInfo &RI = getRegionInfo(BB);
331 // Compute the replacement information for this block...
332 ComputeReplacements(RI);
334 // If debugging, print computed region information...
335 DEBUG(RI.print(std::cerr));
337 // Simplify the contents of this block...
338 bool Changed = SimplifyBasicBlock(*BB, RI);
340 // Get the terminator of this basic block...
341 TerminatorInst *TI = BB->getTerminator();
343 // Loop over all of the blocks that this block is the immediate dominator for.
344 // Because all information known in this region is also known in all of the
345 // blocks that are dominated by this one, we can safely propagate the
346 // information down now.
348 DominatorTree::Node *BBN = (*DT)[BB];
349 if (!RI.empty()) // Time opt: only propagate if we can change something
350 for (unsigned i = 0, e = BBN->getChildren().size(); i != e; ++i) {
351 BasicBlock *Dominated = BBN->getChildren()[i]->getBlock();
352 assert(RegionInfoMap.find(Dominated) == RegionInfoMap.end() &&
353 "RegionInfo should be calculated in dominanace order!");
354 getRegionInfo(Dominated) = RI;
357 // Now that all of our successors have information if they deserve it,
358 // propagate any information our terminator instruction finds to our
360 if (BranchInst *BI = dyn_cast<BranchInst>(TI))
361 if (BI->isConditional())
362 PropagateBranchInfo(BI);
364 // If this is a branch to a block outside our region that simply performs
365 // another conditional branch, one whose outcome is known inside of this
366 // region, then vector this outgoing edge directly to the known destination.
368 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
369 while (ForwardCorrelatedEdgeDestination(TI, i, RI)) {
374 // Now that all of our successors have information, recursively process them.
375 for (unsigned i = 0, e = BBN->getChildren().size(); i != e; ++i)
376 Changed |= TransformRegion(BBN->getChildren()[i]->getBlock(),VisitedBlocks);
381 // isBlockSimpleEnoughForCheck to see if the block is simple enough for us to
382 // revector the conditional branch in the bottom of the block, do so now.
384 static bool isBlockSimpleEnough(BasicBlock *BB) {
385 assert(isa<BranchInst>(BB->getTerminator()));
386 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
387 assert(BI->isConditional());
389 // Check the common case first: empty block, or block with just a setcc.
390 if (BB->size() == 1 ||
391 (BB->size() == 2 && &BB->front() == BI->getCondition() &&
392 BI->getCondition()->hasOneUse()))
395 // Check the more complex case now...
396 BasicBlock::iterator I = BB->begin();
398 // FIXME: This should be reenabled once the regression with SIM is fixed!
400 // PHI Nodes are ok, just skip over them...
401 while (isa<PHINode>(*I)) ++I;
404 // Accept the setcc instruction...
405 if (&*I == BI->getCondition())
408 // Nothing else is acceptable here yet. We must not revector... unless we are
409 // at the terminator instruction.
417 bool CEE::ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
419 // If this successor is a simple block not in the current region, which
420 // contains only a conditional branch, we decide if the outcome of the branch
421 // can be determined from information inside of the region. Instead of going
422 // to this block, we can instead go to the destination we know is the right
426 // Check to see if we dominate the block. If so, this block will get the
427 // condition turned to a constant anyway.
429 //if (DS->dominates(RI.getEntryBlock(), BB))
432 BasicBlock *BB = TI->getParent();
434 // Get the destination block of this edge...
435 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
437 // Make sure that the block ends with a conditional branch and is simple
438 // enough for use to be able to revector over.
439 BranchInst *BI = dyn_cast<BranchInst>(OldSucc->getTerminator());
440 if (BI == 0 || !BI->isConditional() || !isBlockSimpleEnough(OldSucc))
443 // We can only forward the branch over the block if the block ends with a
444 // setcc we can determine the outcome for.
446 // FIXME: we can make this more generic. Code below already handles more
448 SetCondInst *SCI = dyn_cast<SetCondInst>(BI->getCondition());
449 if (SCI == 0) return false;
451 // Make a new RegionInfo structure so that we can simulate the effect of the
452 // PHI nodes in the block we are skipping over...
454 RegionInfo NewRI(RI);
456 // Remove value information for all of the values we are simulating... to make
457 // sure we don't have any stale information.
458 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
459 if (I->getType() != Type::VoidTy)
460 NewRI.removeValueInfo(I);
462 // Put the newly discovered information into the RegionInfo...
463 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
464 if (PHINode *PN = dyn_cast<PHINode>(I)) {
465 int OpNum = PN->getBasicBlockIndex(BB);
466 assert(OpNum != -1 && "PHI doesn't have incoming edge for predecessor!?");
467 PropagateEquality(PN, PN->getIncomingValue(OpNum), NewRI);
468 } else if (SetCondInst *SCI = dyn_cast<SetCondInst>(I)) {
469 Relation::KnownResult Res = getSetCCResult(SCI, NewRI);
470 if (Res == Relation::Unknown) return false;
471 PropagateEquality(SCI, ConstantBool::get(Res), NewRI);
473 assert(isa<BranchInst>(*I) && "Unexpected instruction type!");
476 // Compute the facts implied by what we have discovered...
477 ComputeReplacements(NewRI);
479 ValueInfo &PredicateVI = NewRI.getValueInfo(BI->getCondition());
480 if (PredicateVI.getReplacement() &&
481 isa<Constant>(PredicateVI.getReplacement()) &&
482 !isa<GlobalValue>(PredicateVI.getReplacement())) {
483 ConstantBool *CB = cast<ConstantBool>(PredicateVI.getReplacement());
485 // Forward to the successor that corresponds to the branch we will take.
486 ForwardSuccessorTo(TI, SuccNo, BI->getSuccessor(!CB->getValue()), NewRI);
493 static Value *getReplacementOrValue(Value *V, RegionInfo &RI) {
494 if (const ValueInfo *VI = RI.requestValueInfo(V))
495 if (Value *Repl = VI->getReplacement())
500 /// ForwardSuccessorTo - We have found that we can forward successor # 'SuccNo'
501 /// of Terminator 'TI' to the 'Dest' BasicBlock. This method performs the
502 /// mechanics of updating SSA information and revectoring the branch.
504 void CEE::ForwardSuccessorTo(TerminatorInst *TI, unsigned SuccNo,
505 BasicBlock *Dest, RegionInfo &RI) {
506 // If there are any PHI nodes in the Dest BB, we must duplicate the entry
507 // in the PHI node for the old successor to now include an entry from the
508 // current basic block.
510 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
511 BasicBlock *BB = TI->getParent();
513 DEBUG(std::cerr << "Forwarding branch in basic block %" << BB->getName()
514 << " from block %" << OldSucc->getName() << " to block %"
515 << Dest->getName() << "\n");
517 DEBUG(std::cerr << "Before forwarding: " << *BB->getParent());
519 // Because we know that there cannot be critical edges in the flow graph, and
520 // that OldSucc has multiple outgoing edges, this means that Dest cannot have
521 // multiple incoming edges.
524 pred_iterator DPI = pred_begin(Dest); ++DPI;
525 assert(DPI == pred_end(Dest) && "Critical edge found!!");
528 // Loop over any PHI nodes in the destination, eliminating them, because they
529 // may only have one input.
531 while (PHINode *PN = dyn_cast<PHINode>(&Dest->front())) {
532 assert(PN->getNumIncomingValues() == 1 && "Crit edge found!");
533 // Eliminate the PHI node
534 PN->replaceAllUsesWith(PN->getIncomingValue(0));
535 Dest->getInstList().erase(PN);
538 // If there are values defined in the "OldSucc" basic block, we need to insert
539 // PHI nodes in the regions we are dealing with to emulate them. This can
540 // insert dead phi nodes, but it is more trouble to see if they are used than
541 // to just blindly insert them.
543 if (DS->dominates(OldSucc, Dest)) {
544 // RegionExitBlocks - Find all of the blocks that are not dominated by Dest,
545 // but have predecessors that are. Additionally, prune down the set to only
546 // include blocks that are dominated by OldSucc as well.
548 std::vector<BasicBlock*> RegionExitBlocks;
549 CalculateRegionExitBlocks(Dest, OldSucc, RegionExitBlocks);
551 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end();
553 if (I->getType() != Type::VoidTy) {
554 // Create and insert the PHI node into the top of Dest.
555 PHINode *NewPN = new PHINode(I->getType(), I->getName()+".fw_merge",
557 // There is definitely an edge from OldSucc... add the edge now
558 NewPN->addIncoming(I, OldSucc);
560 // There is also an edge from BB now, add the edge with the calculated
561 // value from the RI.
562 NewPN->addIncoming(getReplacementOrValue(I, RI), BB);
564 // Make everything in the Dest region use the new PHI node now...
565 ReplaceUsesOfValueInRegion(I, NewPN, Dest);
567 // Make sure that exits out of the region dominated by NewPN get PHI
568 // nodes that merge the values as appropriate.
569 InsertRegionExitMerges(NewPN, I, RegionExitBlocks);
573 // If there were PHI nodes in OldSucc, we need to remove the entry for this
574 // edge from the PHI node, and we need to replace any references to the PHI
575 // node with a new value.
577 for (BasicBlock::iterator I = OldSucc->begin(); isa<PHINode>(I); ) {
578 PHINode *PN = cast<PHINode>(I);
580 // Get the value flowing across the old edge and remove the PHI node entry
581 // for this edge: we are about to remove the edge! Don't remove the PHI
582 // node yet though if this is the last edge into it.
583 Value *EdgeValue = PN->removeIncomingValue(BB, false);
585 // Make sure that anything that used to use PN now refers to EdgeValue
586 ReplaceUsesOfValueInRegion(PN, EdgeValue, Dest);
588 // If there is only one value left coming into the PHI node, replace the PHI
589 // node itself with the one incoming value left.
591 if (PN->getNumIncomingValues() == 1) {
592 assert(PN->getNumIncomingValues() == 1);
593 PN->replaceAllUsesWith(PN->getIncomingValue(0));
594 PN->getParent()->getInstList().erase(PN);
595 I = OldSucc->begin();
596 } else if (PN->getNumIncomingValues() == 0) { // Nuke the PHI
597 // If we removed the last incoming value to this PHI, nuke the PHI node
599 PN->replaceAllUsesWith(Constant::getNullValue(PN->getType()));
600 PN->getParent()->getInstList().erase(PN);
601 I = OldSucc->begin();
603 ++I; // Otherwise, move on to the next PHI node
607 // Actually revector the branch now...
608 TI->setSuccessor(SuccNo, Dest);
610 // If we just introduced a critical edge in the flow graph, make sure to break
612 SplitCriticalEdge(TI, SuccNo, this);
614 // Make sure that we don't introduce critical edges from oldsucc now!
615 for (unsigned i = 0, e = OldSucc->getTerminator()->getNumSuccessors();
617 if (isCriticalEdge(OldSucc->getTerminator(), i))
618 SplitCriticalEdge(OldSucc->getTerminator(), i, this);
620 // Since we invalidated the CFG, recalculate the dominator set so that it is
621 // useful for later processing!
622 // FIXME: This is much worse than it really should be!
625 DEBUG(std::cerr << "After forwarding: " << *BB->getParent());
628 /// ReplaceUsesOfValueInRegion - This method replaces all uses of Orig with uses
629 /// of New. It only affects instructions that are defined in basic blocks that
630 /// are dominated by Head.
632 void CEE::ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
633 BasicBlock *RegionDominator) {
634 assert(Orig != New && "Cannot replace value with itself");
635 std::vector<Instruction*> InstsToChange;
636 std::vector<PHINode*> PHIsToChange;
637 InstsToChange.reserve(Orig->use_size());
639 // Loop over instructions adding them to InstsToChange vector, this allows us
640 // an easy way to avoid invalidating the use_iterator at a bad time.
641 for (Value::use_iterator I = Orig->use_begin(), E = Orig->use_end();
643 if (Instruction *User = dyn_cast<Instruction>(*I))
644 if (DS->dominates(RegionDominator, User->getParent()))
645 InstsToChange.push_back(User);
646 else if (PHINode *PN = dyn_cast<PHINode>(User)) {
647 PHIsToChange.push_back(PN);
650 // PHIsToChange contains PHI nodes that use Orig that do not live in blocks
651 // dominated by orig. If the block the value flows in from is dominated by
652 // RegionDominator, then we rewrite the PHI
653 for (unsigned i = 0, e = PHIsToChange.size(); i != e; ++i) {
654 PHINode *PN = PHIsToChange[i];
655 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
656 if (PN->getIncomingValue(j) == Orig &&
657 DS->dominates(RegionDominator, PN->getIncomingBlock(j)))
658 PN->setIncomingValue(j, New);
661 // Loop over the InstsToChange list, replacing all uses of Orig with uses of
662 // New. This list contains all of the instructions in our region that use
664 for (unsigned i = 0, e = InstsToChange.size(); i != e; ++i)
665 if (PHINode *PN = dyn_cast<PHINode>(InstsToChange[i])) {
666 // PHINodes must be handled carefully. If the PHI node itself is in the
667 // region, we have to make sure to only do the replacement for incoming
668 // values that correspond to basic blocks in the region.
669 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
670 if (PN->getIncomingValue(j) == Orig &&
671 DS->dominates(RegionDominator, PN->getIncomingBlock(j)))
672 PN->setIncomingValue(j, New);
675 InstsToChange[i]->replaceUsesOfWith(Orig, New);
679 static void CalcRegionExitBlocks(BasicBlock *Header, BasicBlock *BB,
680 std::set<BasicBlock*> &Visited,
682 std::vector<BasicBlock*> &RegionExitBlocks) {
683 if (Visited.count(BB)) return;
686 if (DS.dominates(Header, BB)) { // Block in the region, recursively traverse
687 for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
688 CalcRegionExitBlocks(Header, *I, Visited, DS, RegionExitBlocks);
690 // Header does not dominate this block, but we have a predecessor that does
691 // dominate us. Add ourself to the list.
692 RegionExitBlocks.push_back(BB);
696 /// CalculateRegionExitBlocks - Find all of the blocks that are not dominated by
697 /// BB, but have predecessors that are. Additionally, prune down the set to
698 /// only include blocks that are dominated by OldSucc as well.
700 void CEE::CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
701 std::vector<BasicBlock*> &RegionExitBlocks){
702 std::set<BasicBlock*> Visited; // Don't infinite loop
704 // Recursively calculate blocks we are interested in...
705 CalcRegionExitBlocks(BB, BB, Visited, *DS, RegionExitBlocks);
707 // Filter out blocks that are not dominated by OldSucc...
708 for (unsigned i = 0; i != RegionExitBlocks.size(); ) {
709 if (DS->dominates(OldSucc, RegionExitBlocks[i]))
710 ++i; // Block is ok, keep it.
712 // Move to end of list...
713 std::swap(RegionExitBlocks[i], RegionExitBlocks.back());
714 RegionExitBlocks.pop_back(); // Nuke the end
719 void CEE::InsertRegionExitMerges(PHINode *BBVal, Instruction *OldVal,
720 const std::vector<BasicBlock*> &RegionExitBlocks) {
721 assert(BBVal->getType() == OldVal->getType() && "Should be derived values!");
722 BasicBlock *BB = BBVal->getParent();
723 BasicBlock *OldSucc = OldVal->getParent();
725 // Loop over all of the blocks we have to place PHIs in, doing it.
726 for (unsigned i = 0, e = RegionExitBlocks.size(); i != e; ++i) {
727 BasicBlock *FBlock = RegionExitBlocks[i]; // Block on the frontier
729 // Create the new PHI node
730 PHINode *NewPN = new PHINode(BBVal->getType(),
731 OldVal->getName()+".fw_frontier",
734 // Add an incoming value for every predecessor of the block...
735 for (pred_iterator PI = pred_begin(FBlock), PE = pred_end(FBlock);
737 // If the incoming edge is from the region dominated by BB, use BBVal,
738 // otherwise use OldVal.
739 NewPN->addIncoming(DS->dominates(BB, *PI) ? BBVal : OldVal, *PI);
742 // Now make everyone dominated by this block use this new value!
743 ReplaceUsesOfValueInRegion(OldVal, NewPN, FBlock);
749 // BuildRankMap - This method builds the rank map data structure which gives
750 // each instruction/value in the function a value based on how early it appears
751 // in the function. We give constants and globals rank 0, arguments are
752 // numbered starting at one, and instructions are numbered in reverse post-order
753 // from where the arguments leave off. This gives instructions in loops higher
754 // values than instructions not in loops.
756 void CEE::BuildRankMap(Function &F) {
757 unsigned Rank = 1; // Skip rank zero.
759 // Number the arguments...
760 for (Function::aiterator I = F.abegin(), E = F.aend(); I != E; ++I)
763 // Number the instructions in reverse post order...
764 ReversePostOrderTraversal<Function*> RPOT(&F);
765 for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
766 E = RPOT.end(); I != E; ++I)
767 for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end();
769 if (BBI->getType() != Type::VoidTy)
770 RankMap[BBI] = Rank++;
774 // PropagateBranchInfo - When this method is invoked, we need to propagate
775 // information derived from the branch condition into the true and false
776 // branches of BI. Since we know that there aren't any critical edges in the
777 // flow graph, this can proceed unconditionally.
779 void CEE::PropagateBranchInfo(BranchInst *BI) {
780 assert(BI->isConditional() && "Must be a conditional branch!");
782 // Propagate information into the true block...
784 PropagateEquality(BI->getCondition(), ConstantBool::True,
785 getRegionInfo(BI->getSuccessor(0)));
787 // Propagate information into the false block...
789 PropagateEquality(BI->getCondition(), ConstantBool::False,
790 getRegionInfo(BI->getSuccessor(1)));
794 // PropagateEquality - If we discover that two values are equal to each other in
795 // a specified region, propagate this knowledge recursively.
797 void CEE::PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI) {
798 if (Op0 == Op1) return; // Gee whiz. Are these really equal each other?
800 if (isa<Constant>(Op0)) // Make sure the constant is always Op1
803 // Make sure we don't already know these are equal, to avoid infinite loops...
804 ValueInfo &VI = RI.getValueInfo(Op0);
806 // Get information about the known relationship between Op0 & Op1
807 Relation &KnownRelation = VI.getRelation(Op1);
809 // If we already know they're equal, don't reprocess...
810 if (KnownRelation.getRelation() == Instruction::SetEQ)
813 // If this is boolean, check to see if one of the operands is a constant. If
814 // it's a constant, then see if the other one is one of a setcc instruction,
815 // an AND, OR, or XOR instruction.
817 if (ConstantBool *CB = dyn_cast<ConstantBool>(Op1)) {
819 if (Instruction *Inst = dyn_cast<Instruction>(Op0)) {
820 // If we know that this instruction is an AND instruction, and the result
821 // is true, this means that both operands to the OR are known to be true
824 if (CB->getValue() && Inst->getOpcode() == Instruction::And) {
825 PropagateEquality(Inst->getOperand(0), CB, RI);
826 PropagateEquality(Inst->getOperand(1), CB, RI);
829 // If we know that this instruction is an OR instruction, and the result
830 // is false, this means that both operands to the OR are know to be false
833 if (!CB->getValue() && Inst->getOpcode() == Instruction::Or) {
834 PropagateEquality(Inst->getOperand(0), CB, RI);
835 PropagateEquality(Inst->getOperand(1), CB, RI);
838 // If we know that this instruction is a NOT instruction, we know that the
839 // operand is known to be the inverse of whatever the current value is.
841 if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(Inst))
842 if (BinaryOperator::isNot(BOp))
843 PropagateEquality(BinaryOperator::getNotArgument(BOp),
844 ConstantBool::get(!CB->getValue()), RI);
846 // If we know the value of a SetCC instruction, propagate the information
847 // about the relation into this region as well.
849 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Inst)) {
850 if (CB->getValue()) { // If we know the condition is true...
851 // Propagate info about the LHS to the RHS & RHS to LHS
852 PropagateRelation(SCI->getOpcode(), SCI->getOperand(0),
853 SCI->getOperand(1), RI);
854 PropagateRelation(SCI->getSwappedCondition(),
855 SCI->getOperand(1), SCI->getOperand(0), RI);
857 } else { // If we know the condition is false...
858 // We know the opposite of the condition is true...
859 Instruction::BinaryOps C = SCI->getInverseCondition();
861 PropagateRelation(C, SCI->getOperand(0), SCI->getOperand(1), RI);
862 PropagateRelation(SetCondInst::getSwappedCondition(C),
863 SCI->getOperand(1), SCI->getOperand(0), RI);
869 // Propagate information about Op0 to Op1 & visa versa
870 PropagateRelation(Instruction::SetEQ, Op0, Op1, RI);
871 PropagateRelation(Instruction::SetEQ, Op1, Op0, RI);
875 // PropagateRelation - We know that the specified relation is true in all of the
876 // blocks in the specified region. Propagate the information about Op0 and
877 // anything derived from it into this region.
879 void CEE::PropagateRelation(Instruction::BinaryOps Opcode, Value *Op0,
880 Value *Op1, RegionInfo &RI) {
881 assert(Op0->getType() == Op1->getType() && "Equal types expected!");
883 // Constants are already pretty well understood. We will apply information
884 // about the constant to Op1 in another call to PropagateRelation.
886 if (isa<Constant>(Op0)) return;
888 // Get the region information for this block to update...
889 ValueInfo &VI = RI.getValueInfo(Op0);
891 // Get information about the known relationship between Op0 & Op1
892 Relation &Op1R = VI.getRelation(Op1);
894 // Quick bailout for common case if we are reprocessing an instruction...
895 if (Op1R.getRelation() == Opcode)
898 // If we already have information that contradicts the current information we
899 // are propagating, ignore this info. Something bad must have happened!
901 if (Op1R.contradicts(Opcode, VI)) {
902 Op1R.contradicts(Opcode, VI);
903 std::cerr << "Contradiction found for opcode: "
904 << Instruction::getOpcodeName(Opcode) << "\n";
905 Op1R.print(std::cerr);
909 // If the information propagated is new, then we want process the uses of this
910 // instruction to propagate the information down to them.
912 if (Op1R.incorporate(Opcode, VI))
913 UpdateUsersOfValue(Op0, RI);
917 // UpdateUsersOfValue - The information about V in this region has been updated.
918 // Propagate this to all consumers of the value.
920 void CEE::UpdateUsersOfValue(Value *V, RegionInfo &RI) {
921 for (Value::use_iterator I = V->use_begin(), E = V->use_end();
923 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
924 // If this is an instruction using a value that we know something about,
925 // try to propagate information to the value produced by the
926 // instruction. We can only do this if it is an instruction we can
927 // propagate information for (a setcc for example), and we only WANT to
928 // do this if the instruction dominates this region.
930 // If the instruction doesn't dominate this region, then it cannot be
931 // used in this region and we don't care about it. If the instruction
932 // is IN this region, then we will simplify the instruction before we
933 // get to uses of it anyway, so there is no reason to bother with it
934 // here. This check is also effectively checking to make sure that Inst
935 // is in the same function as our region (in case V is a global f.e.).
937 if (DS->properlyDominates(Inst->getParent(), RI.getEntryBlock()))
938 IncorporateInstruction(Inst, RI);
942 // IncorporateInstruction - We just updated the information about one of the
943 // operands to the specified instruction. Update the information about the
944 // value produced by this instruction
946 void CEE::IncorporateInstruction(Instruction *Inst, RegionInfo &RI) {
947 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Inst)) {
948 // See if we can figure out a result for this instruction...
949 Relation::KnownResult Result = getSetCCResult(SCI, RI);
950 if (Result != Relation::Unknown) {
951 PropagateEquality(SCI, Result ? ConstantBool::True : ConstantBool::False,
958 // ComputeReplacements - Some values are known to be equal to other values in a
959 // region. For example if there is a comparison of equality between a variable
960 // X and a constant C, we can replace all uses of X with C in the region we are
961 // interested in. We generalize this replacement to replace variables with
962 // other variables if they are equal and there is a variable with lower rank
963 // than the current one. This offers a canonicalizing property that exposes
964 // more redundancies for later transformations to take advantage of.
966 void CEE::ComputeReplacements(RegionInfo &RI) {
967 // Loop over all of the values in the region info map...
968 for (RegionInfo::iterator I = RI.begin(), E = RI.end(); I != E; ++I) {
969 ValueInfo &VI = I->second;
971 // If we know that this value is a particular constant, set Replacement to
973 Value *Replacement = VI.getBounds().getSingleElement();
975 // If this value is not known to be some constant, figure out the lowest
976 // rank value that it is known to be equal to (if anything).
978 if (Replacement == 0) {
979 // Find out if there are any equality relationships with values of lower
980 // rank than VI itself...
981 unsigned MinRank = getRank(I->first);
983 // Loop over the relationships known about Op0.
984 const std::vector<Relation> &Relationships = VI.getRelationships();
985 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
986 if (Relationships[i].getRelation() == Instruction::SetEQ) {
987 unsigned R = getRank(Relationships[i].getValue());
990 Replacement = Relationships[i].getValue();
995 // If we found something to replace this value with, keep track of it.
997 VI.setReplacement(Replacement);
1001 // SimplifyBasicBlock - Given information about values in region RI, simplify
1002 // the instructions in the specified basic block.
1004 bool CEE::SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI) {
1005 bool Changed = false;
1006 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ) {
1007 Instruction *Inst = I++;
1009 // Convert instruction arguments to canonical forms...
1010 Changed |= SimplifyInstruction(Inst, RI);
1012 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Inst)) {
1013 // Try to simplify a setcc instruction based on inherited information
1014 Relation::KnownResult Result = getSetCCResult(SCI, RI);
1015 if (Result != Relation::Unknown) {
1016 DEBUG(std::cerr << "Replacing setcc with " << Result
1017 << " constant: " << *SCI);
1019 SCI->replaceAllUsesWith(ConstantBool::get((bool)Result));
1020 // The instruction is now dead, remove it from the program.
1021 SCI->getParent()->getInstList().erase(SCI);
1031 // SimplifyInstruction - Inspect the operands of the instruction, converting
1032 // them to their canonical form if possible. This takes care of, for example,
1033 // replacing a value 'X' with a constant 'C' if the instruction in question is
1034 // dominated by a true seteq 'X', 'C'.
1036 bool CEE::SimplifyInstruction(Instruction *I, const RegionInfo &RI) {
1037 bool Changed = false;
1039 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1040 if (const ValueInfo *VI = RI.requestValueInfo(I->getOperand(i)))
1041 if (Value *Repl = VI->getReplacement()) {
1042 // If we know if a replacement with lower rank than Op0, make the
1044 DEBUG(std::cerr << "In Inst: " << *I << " Replacing operand #" << i
1045 << " with " << *Repl << "\n");
1046 I->setOperand(i, Repl);
1055 // getSetCCResult - Try to simplify a setcc instruction based on information
1056 // inherited from a dominating setcc instruction. V is one of the operands to
1057 // the setcc instruction, and VI is the set of information known about it. We
1058 // take two cases into consideration here. If the comparison is against a
1059 // constant value, we can use the constant range to see if the comparison is
1060 // possible to succeed. If it is not a comparison against a constant, we check
1061 // to see if there is a known relationship between the two values. If so, we
1062 // may be able to eliminate the check.
1064 Relation::KnownResult CEE::getSetCCResult(SetCondInst *SCI,
1065 const RegionInfo &RI) {
1066 Value *Op0 = SCI->getOperand(0), *Op1 = SCI->getOperand(1);
1067 Instruction::BinaryOps Opcode = SCI->getOpcode();
1069 if (isa<Constant>(Op0)) {
1070 if (isa<Constant>(Op1)) {
1071 if (Constant *Result = ConstantFoldInstruction(SCI)) {
1072 // Wow, this is easy, directly eliminate the SetCondInst.
1073 DEBUG(std::cerr << "Replacing setcc with constant fold: " << *SCI);
1074 return cast<ConstantBool>(Result)->getValue()
1075 ? Relation::KnownTrue : Relation::KnownFalse;
1078 // We want to swap this instruction so that operand #0 is the constant.
1079 std::swap(Op0, Op1);
1080 Opcode = SCI->getSwappedCondition();
1084 // Try to figure out what the result of this comparison will be...
1085 Relation::KnownResult Result = Relation::Unknown;
1087 // We have to know something about the relationship to prove anything...
1088 if (const ValueInfo *Op0VI = RI.requestValueInfo(Op0)) {
1090 // At this point, we know that if we have a constant argument that it is in
1091 // Op1. Check to see if we know anything about comparing value with a
1092 // constant, and if we can use this info to fold the setcc.
1094 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(Op1)) {
1095 // Check to see if we already know the result of this comparison...
1096 ConstantRange R = ConstantRange(Opcode, C);
1097 ConstantRange Int = R.intersectWith(Op0VI->getBounds());
1099 // If the intersection of the two ranges is empty, then the condition
1100 // could never be true!
1102 if (Int.isEmptySet()) {
1103 Result = Relation::KnownFalse;
1105 // Otherwise, if VI.getBounds() (the possible values) is a subset of R
1106 // (the allowed values) then we know that the condition must always be
1109 } else if (Int == Op0VI->getBounds()) {
1110 Result = Relation::KnownTrue;
1113 // If we are here, we know that the second argument is not a constant
1114 // integral. See if we know anything about Op0 & Op1 that allows us to
1115 // fold this anyway.
1117 // Do we have value information about Op0 and a relation to Op1?
1118 if (const Relation *Op2R = Op0VI->requestRelation(Op1))
1119 Result = Op2R->getImpliedResult(Opcode);
1125 //===----------------------------------------------------------------------===//
1126 // Relation Implementation
1127 //===----------------------------------------------------------------------===//
1129 // CheckCondition - Return true if the specified condition is false. Bound may
1131 static bool CheckCondition(Constant *Bound, Constant *C,
1132 Instruction::BinaryOps BO) {
1133 assert(C != 0 && "C is not specified!");
1134 if (Bound == 0) return false;
1136 Constant *Val = ConstantExpr::get(BO, Bound, C);
1137 if (ConstantBool *CB = dyn_cast<ConstantBool>(Val))
1138 return !CB->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); }