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/Pass.h"
31 #include "llvm/Function.h"
32 #include "llvm/iTerminators.h"
33 #include "llvm/iPHINode.h"
34 #include "llvm/iOperators.h"
35 #include "llvm/ConstantHandling.h"
36 #include "llvm/Assembly/Writer.h"
37 #include "llvm/Analysis/Dominators.h"
38 #include "llvm/Transforms/Utils/Local.h"
39 #include "llvm/Support/ConstantRange.h"
40 #include "llvm/Support/CFG.h"
41 #include "Support/Debug.h"
42 #include "Support/PostOrderIterator.h"
43 #include "Support/Statistic.h"
47 Statistic<> NumSetCCRemoved("cee", "Number of setcc instruction eliminated");
48 Statistic<> NumOperandsCann("cee", "Number of operands canonicalized");
49 Statistic<> BranchRevectors("cee", "Number of branches revectored");
53 Value *Val; // Relation to what value?
54 Instruction::BinaryOps Rel; // SetCC relation, or Add if no information
56 Relation(Value *V) : Val(V), Rel(Instruction::Add) {}
57 bool operator<(const Relation &R) const { return Val < R.Val; }
58 Value *getValue() const { return Val; }
59 Instruction::BinaryOps getRelation() const { return Rel; }
61 // contradicts - Return true if the relationship specified by the operand
62 // contradicts already known information.
64 bool contradicts(Instruction::BinaryOps Rel, const ValueInfo &VI) const;
66 // incorporate - Incorporate information in the argument into this relation
67 // entry. This assumes that the information doesn't contradict itself. If
68 // any new information is gained, true is returned, otherwise false is
69 // returned to indicate that nothing was updated.
71 bool incorporate(Instruction::BinaryOps Rel, ValueInfo &VI);
73 // KnownResult - Whether or not this condition determines the result of a
74 // setcc in the program. False & True are intentionally 0 & 1 so we can
75 // convert to bool by casting after checking for unknown.
77 enum KnownResult { KnownFalse = 0, KnownTrue = 1, Unknown = 2 };
79 // getImpliedResult - If this relationship between two values implies that
80 // the specified relationship is true or false, return that. If we cannot
81 // determine the result required, return Unknown.
83 KnownResult getImpliedResult(Instruction::BinaryOps Rel) const;
85 // print - Output this relation to the specified stream
86 void print(std::ostream &OS) const;
91 // ValueInfo - One instance of this record exists for every value with
92 // relationships between other values. It keeps track of all of the
93 // relationships to other values in the program (specified with Relation) that
94 // are known to be valid in a region.
97 // RelationShips - this value is know to have the specified relationships to
98 // other values. There can only be one entry per value, and this list is
99 // kept sorted by the Val field.
100 std::vector<Relation> Relationships;
102 // If information about this value is known or propagated from constant
103 // expressions, this range contains the possible values this value may hold.
104 ConstantRange Bounds;
106 // If we find that this value is equal to another value that has a lower
107 // rank, this value is used as it's replacement.
111 ValueInfo(const Type *Ty)
112 : Bounds(Ty->isIntegral() ? Ty : Type::IntTy), Replacement(0) {}
114 // getBounds() - Return the constant bounds of the value...
115 const ConstantRange &getBounds() const { return Bounds; }
116 ConstantRange &getBounds() { return Bounds; }
118 const std::vector<Relation> &getRelationships() { return Relationships; }
120 // getReplacement - Return the value this value is to be replaced with if it
121 // exists, otherwise return null.
123 Value *getReplacement() const { return Replacement; }
125 // setReplacement - Used by the replacement calculation pass to figure out
126 // what to replace this value with, if anything.
128 void setReplacement(Value *Repl) { Replacement = Repl; }
130 // getRelation - return the relationship entry for the specified value.
131 // This can invalidate references to other Relations, so use it carefully.
133 Relation &getRelation(Value *V) {
134 // Binary search for V's entry...
135 std::vector<Relation>::iterator I =
136 std::lower_bound(Relationships.begin(), Relationships.end(), V);
138 // If we found the entry, return it...
139 if (I != Relationships.end() && I->getValue() == V)
142 // Insert and return the new relationship...
143 return *Relationships.insert(I, V);
146 const Relation *requestRelation(Value *V) const {
147 // Binary search for V's entry...
148 std::vector<Relation>::const_iterator I =
149 std::lower_bound(Relationships.begin(), Relationships.end(), V);
150 if (I != Relationships.end() && I->getValue() == V)
155 // print - Output information about this value relation...
156 void print(std::ostream &OS, Value *V) const;
160 // RegionInfo - Keeps track of all of the value relationships for a region. A
161 // region is the are dominated by a basic block. RegionInfo's keep track of
162 // the RegionInfo for their dominator, because anything known in a dominator
163 // is known to be true in a dominated block as well.
168 // ValueMap - Tracks the ValueInformation known for this region
169 typedef std::map<Value*, ValueInfo> ValueMapTy;
172 RegionInfo(BasicBlock *bb) : BB(bb) {}
174 // getEntryBlock - Return the block that dominates all of the members of
176 BasicBlock *getEntryBlock() const { return BB; }
178 // empty - return true if this region has no information known about it.
179 bool empty() const { return ValueMap.empty(); }
181 const RegionInfo &operator=(const RegionInfo &RI) {
182 ValueMap = RI.ValueMap;
186 // print - Output information about this region...
187 void print(std::ostream &OS) const;
190 // Allow external access.
191 typedef ValueMapTy::iterator iterator;
192 iterator begin() { return ValueMap.begin(); }
193 iterator end() { return ValueMap.end(); }
195 ValueInfo &getValueInfo(Value *V) {
196 ValueMapTy::iterator I = ValueMap.lower_bound(V);
197 if (I != ValueMap.end() && I->first == V) return I->second;
198 return ValueMap.insert(I, std::make_pair(V, V->getType()))->second;
201 const ValueInfo *requestValueInfo(Value *V) const {
202 ValueMapTy::const_iterator I = ValueMap.find(V);
203 if (I != ValueMap.end()) return &I->second;
207 /// removeValueInfo - Remove anything known about V from our records. This
208 /// works whether or not we know anything about V.
210 void removeValueInfo(Value *V) {
215 /// CEE - Correlated Expression Elimination
216 class CEE : public FunctionPass {
217 std::map<Value*, unsigned> RankMap;
218 std::map<BasicBlock*, RegionInfo> RegionInfoMap;
222 virtual bool runOnFunction(Function &F);
224 // We don't modify the program, so we preserve all analyses
225 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
226 AU.addRequired<DominatorSet>();
227 AU.addRequired<DominatorTree>();
228 AU.addRequiredID(BreakCriticalEdgesID);
231 // print - Implement the standard print form to print out analysis
233 virtual void print(std::ostream &O, const Module *M) const;
236 RegionInfo &getRegionInfo(BasicBlock *BB) {
237 std::map<BasicBlock*, RegionInfo>::iterator I
238 = RegionInfoMap.lower_bound(BB);
239 if (I != RegionInfoMap.end() && I->first == BB) return I->second;
240 return RegionInfoMap.insert(I, std::make_pair(BB, BB))->second;
243 void BuildRankMap(Function &F);
244 unsigned getRank(Value *V) const {
245 if (isa<Constant>(V) || isa<GlobalValue>(V)) return 0;
246 std::map<Value*, unsigned>::const_iterator I = RankMap.find(V);
247 if (I != RankMap.end()) return I->second;
248 return 0; // Must be some other global thing
251 bool TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks);
253 bool ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
256 void ForwardSuccessorTo(TerminatorInst *TI, unsigned Succ, BasicBlock *D,
258 void ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
259 BasicBlock *RegionDominator);
260 void CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
261 std::vector<BasicBlock*> &RegionExitBlocks);
262 void InsertRegionExitMerges(PHINode *NewPHI, Instruction *OldVal,
263 const std::vector<BasicBlock*> &RegionExitBlocks);
265 void PropagateBranchInfo(BranchInst *BI);
266 void PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI);
267 void PropagateRelation(Instruction::BinaryOps Opcode, Value *Op0,
268 Value *Op1, RegionInfo &RI);
269 void UpdateUsersOfValue(Value *V, RegionInfo &RI);
270 void IncorporateInstruction(Instruction *Inst, RegionInfo &RI);
271 void ComputeReplacements(RegionInfo &RI);
274 // getSetCCResult - Given a setcc instruction, determine if the result is
275 // determined by facts we already know about the region under analysis.
276 // Return KnownTrue, KnownFalse, or Unknown based on what we can determine.
278 Relation::KnownResult getSetCCResult(SetCondInst *SC, const RegionInfo &RI);
281 bool SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI);
282 bool SimplifyInstruction(Instruction *Inst, const RegionInfo &RI);
284 RegisterOpt<CEE> X("cee", "Correlated Expression Elimination");
287 Pass *createCorrelatedExpressionEliminationPass() { return new CEE(); }
290 bool CEE::runOnFunction(Function &F) {
291 // Build a rank map for the function...
294 // Traverse the dominator tree, computing information for each node in the
295 // tree. Note that our traversal will not even touch unreachable basic
297 DS = &getAnalysis<DominatorSet>();
298 DT = &getAnalysis<DominatorTree>();
300 std::set<BasicBlock*> VisitedBlocks;
301 bool Changed = TransformRegion(&F.getEntryBlock(), VisitedBlocks);
303 RegionInfoMap.clear();
308 // TransformRegion - Transform the region starting with BB according to the
309 // calculated region information for the block. Transforming the region
310 // involves analyzing any information this block provides to successors,
311 // propagating the information to successors, and finally transforming
314 // This method processes the function in depth first order, which guarantees
315 // that we process the immediate dominator of a block before the block itself.
316 // Because we are passing information from immediate dominators down to
317 // dominatees, we obviously have to process the information source before the
318 // information consumer.
320 bool CEE::TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks){
321 // Prevent infinite recursion...
322 if (VisitedBlocks.count(BB)) return false;
323 VisitedBlocks.insert(BB);
325 // Get the computed region information for this block...
326 RegionInfo &RI = getRegionInfo(BB);
328 // Compute the replacement information for this block...
329 ComputeReplacements(RI);
331 // If debugging, print computed region information...
332 DEBUG(RI.print(std::cerr));
334 // Simplify the contents of this block...
335 bool Changed = SimplifyBasicBlock(*BB, RI);
337 // Get the terminator of this basic block...
338 TerminatorInst *TI = BB->getTerminator();
340 // Loop over all of the blocks that this block is the immediate dominator for.
341 // Because all information known in this region is also known in all of the
342 // blocks that are dominated by this one, we can safely propagate the
343 // information down now.
345 DominatorTree::Node *BBN = (*DT)[BB];
346 if (!RI.empty()) // Time opt: only propagate if we can change something
347 for (unsigned i = 0, e = BBN->getChildren().size(); i != e; ++i) {
348 BasicBlock *Dominated = BBN->getChildren()[i]->getBlock();
349 assert(RegionInfoMap.find(Dominated) == RegionInfoMap.end() &&
350 "RegionInfo should be calculated in dominanace order!");
351 getRegionInfo(Dominated) = RI;
354 // Now that all of our successors have information if they deserve it,
355 // propagate any information our terminator instruction finds to our
357 if (BranchInst *BI = dyn_cast<BranchInst>(TI))
358 if (BI->isConditional())
359 PropagateBranchInfo(BI);
361 // If this is a branch to a block outside our region that simply performs
362 // another conditional branch, one whose outcome is known inside of this
363 // region, then vector this outgoing edge directly to the known destination.
365 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
366 while (ForwardCorrelatedEdgeDestination(TI, i, RI)) {
371 // Now that all of our successors have information, recursively process them.
372 for (unsigned i = 0, e = BBN->getChildren().size(); i != e; ++i)
373 Changed |= TransformRegion(BBN->getChildren()[i]->getBlock(),VisitedBlocks);
378 // isBlockSimpleEnoughForCheck to see if the block is simple enough for us to
379 // revector the conditional branch in the bottom of the block, do so now.
381 static bool isBlockSimpleEnough(BasicBlock *BB) {
382 assert(isa<BranchInst>(BB->getTerminator()));
383 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
384 assert(BI->isConditional());
386 // Check the common case first: empty block, or block with just a setcc.
387 if (BB->size() == 1 ||
388 (BB->size() == 2 && &BB->front() == BI->getCondition() &&
389 BI->getCondition()->hasOneUse()))
392 // Check the more complex case now...
393 BasicBlock::iterator I = BB->begin();
395 // FIXME: This should be reenabled once the regression with SIM is fixed!
397 // PHI Nodes are ok, just skip over them...
398 while (isa<PHINode>(*I)) ++I;
401 // Accept the setcc instruction...
402 if (&*I == BI->getCondition())
405 // Nothing else is acceptable here yet. We must not revector... unless we are
406 // at the terminator instruction.
414 bool CEE::ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
416 // If this successor is a simple block not in the current region, which
417 // contains only a conditional branch, we decide if the outcome of the branch
418 // can be determined from information inside of the region. Instead of going
419 // to this block, we can instead go to the destination we know is the right
423 // Check to see if we dominate the block. If so, this block will get the
424 // condition turned to a constant anyway.
426 //if (DS->dominates(RI.getEntryBlock(), BB))
429 BasicBlock *BB = TI->getParent();
431 // Get the destination block of this edge...
432 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
434 // Make sure that the block ends with a conditional branch and is simple
435 // enough for use to be able to revector over.
436 BranchInst *BI = dyn_cast<BranchInst>(OldSucc->getTerminator());
437 if (BI == 0 || !BI->isConditional() || !isBlockSimpleEnough(OldSucc))
440 // We can only forward the branch over the block if the block ends with a
441 // setcc we can determine the outcome for.
443 // FIXME: we can make this more generic. Code below already handles more
445 SetCondInst *SCI = dyn_cast<SetCondInst>(BI->getCondition());
446 if (SCI == 0) return false;
448 // Make a new RegionInfo structure so that we can simulate the effect of the
449 // PHI nodes in the block we are skipping over...
451 RegionInfo NewRI(RI);
453 // Remove value information for all of the values we are simulating... to make
454 // sure we don't have any stale information.
455 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
456 if (I->getType() != Type::VoidTy)
457 NewRI.removeValueInfo(I);
459 // Put the newly discovered information into the RegionInfo...
460 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
461 if (PHINode *PN = dyn_cast<PHINode>(I)) {
462 int OpNum = PN->getBasicBlockIndex(BB);
463 assert(OpNum != -1 && "PHI doesn't have incoming edge for predecessor!?");
464 PropagateEquality(PN, PN->getIncomingValue(OpNum), NewRI);
465 } else if (SetCondInst *SCI = dyn_cast<SetCondInst>(I)) {
466 Relation::KnownResult Res = getSetCCResult(SCI, NewRI);
467 if (Res == Relation::Unknown) return false;
468 PropagateEquality(SCI, ConstantBool::get(Res), NewRI);
470 assert(isa<BranchInst>(*I) && "Unexpected instruction type!");
473 // Compute the facts implied by what we have discovered...
474 ComputeReplacements(NewRI);
476 ValueInfo &PredicateVI = NewRI.getValueInfo(BI->getCondition());
477 if (PredicateVI.getReplacement() &&
478 isa<Constant>(PredicateVI.getReplacement())) {
479 ConstantBool *CB = cast<ConstantBool>(PredicateVI.getReplacement());
481 // Forward to the successor that corresponds to the branch we will take.
482 ForwardSuccessorTo(TI, SuccNo, BI->getSuccessor(!CB->getValue()), NewRI);
489 static Value *getReplacementOrValue(Value *V, RegionInfo &RI) {
490 if (const ValueInfo *VI = RI.requestValueInfo(V))
491 if (Value *Repl = VI->getReplacement())
496 /// ForwardSuccessorTo - We have found that we can forward successor # 'SuccNo'
497 /// of Terminator 'TI' to the 'Dest' BasicBlock. This method performs the
498 /// mechanics of updating SSA information and revectoring the branch.
500 void CEE::ForwardSuccessorTo(TerminatorInst *TI, unsigned SuccNo,
501 BasicBlock *Dest, RegionInfo &RI) {
502 // If there are any PHI nodes in the Dest BB, we must duplicate the entry
503 // in the PHI node for the old successor to now include an entry from the
504 // current basic block.
506 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
507 BasicBlock *BB = TI->getParent();
509 DEBUG(std::cerr << "Forwarding branch in basic block %" << BB->getName()
510 << " from block %" << OldSucc->getName() << " to block %"
511 << Dest->getName() << "\n");
513 DEBUG(std::cerr << "Before forwarding: " << *BB->getParent());
515 // Because we know that there cannot be critical edges in the flow graph, and
516 // that OldSucc has multiple outgoing edges, this means that Dest cannot have
517 // multiple incoming edges.
520 pred_iterator DPI = pred_begin(Dest); ++DPI;
521 assert(DPI == pred_end(Dest) && "Critical edge found!!");
524 // Loop over any PHI nodes in the destination, eliminating them, because they
525 // may only have one input.
527 while (PHINode *PN = dyn_cast<PHINode>(&Dest->front())) {
528 assert(PN->getNumIncomingValues() == 1 && "Crit edge found!");
529 // Eliminate the PHI node
530 PN->replaceAllUsesWith(PN->getIncomingValue(0));
531 Dest->getInstList().erase(PN);
534 // If there are values defined in the "OldSucc" basic block, we need to insert
535 // PHI nodes in the regions we are dealing with to emulate them. This can
536 // insert dead phi nodes, but it is more trouble to see if they are used than
537 // to just blindly insert them.
539 if (DS->dominates(OldSucc, Dest)) {
540 // RegionExitBlocks - Find all of the blocks that are not dominated by Dest,
541 // but have predecessors that are. Additionally, prune down the set to only
542 // include blocks that are dominated by OldSucc as well.
544 std::vector<BasicBlock*> RegionExitBlocks;
545 CalculateRegionExitBlocks(Dest, OldSucc, RegionExitBlocks);
547 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end();
549 if (I->getType() != Type::VoidTy) {
550 // Create and insert the PHI node into the top of Dest.
551 PHINode *NewPN = new PHINode(I->getType(), I->getName()+".fw_merge",
553 // There is definitely an edge from OldSucc... add the edge now
554 NewPN->addIncoming(I, OldSucc);
556 // There is also an edge from BB now, add the edge with the calculated
557 // value from the RI.
558 NewPN->addIncoming(getReplacementOrValue(I, RI), BB);
560 // Make everything in the Dest region use the new PHI node now...
561 ReplaceUsesOfValueInRegion(I, NewPN, Dest);
563 // Make sure that exits out of the region dominated by NewPN get PHI
564 // nodes that merge the values as appropriate.
565 InsertRegionExitMerges(NewPN, I, RegionExitBlocks);
569 // If there were PHI nodes in OldSucc, we need to remove the entry for this
570 // edge from the PHI node, and we need to replace any references to the PHI
571 // node with a new value.
573 for (BasicBlock::iterator I = OldSucc->begin();
574 PHINode *PN = dyn_cast<PHINode>(I); ) {
576 // Get the value flowing across the old edge and remove the PHI node entry
577 // for this edge: we are about to remove the edge! Don't remove the PHI
578 // node yet though if this is the last edge into it.
579 Value *EdgeValue = PN->removeIncomingValue(BB, false);
581 // Make sure that anything that used to use PN now refers to EdgeValue
582 ReplaceUsesOfValueInRegion(PN, EdgeValue, Dest);
584 // If there is only one value left coming into the PHI node, replace the PHI
585 // node itself with the one incoming value left.
587 if (PN->getNumIncomingValues() == 1) {
588 assert(PN->getNumIncomingValues() == 1);
589 PN->replaceAllUsesWith(PN->getIncomingValue(0));
590 PN->getParent()->getInstList().erase(PN);
591 I = OldSucc->begin();
592 } else if (PN->getNumIncomingValues() == 0) { // Nuke the PHI
593 // If we removed the last incoming value to this PHI, nuke the PHI node
595 PN->replaceAllUsesWith(Constant::getNullValue(PN->getType()));
596 PN->getParent()->getInstList().erase(PN);
597 I = OldSucc->begin();
599 ++I; // Otherwise, move on to the next PHI node
603 // Actually revector the branch now...
604 TI->setSuccessor(SuccNo, Dest);
606 // If we just introduced a critical edge in the flow graph, make sure to break
608 if (isCriticalEdge(TI, SuccNo))
609 SplitCriticalEdge(TI, SuccNo, this);
611 // Make sure that we don't introduce critical edges from oldsucc now!
612 for (unsigned i = 0, e = OldSucc->getTerminator()->getNumSuccessors();
614 if (isCriticalEdge(OldSucc->getTerminator(), i))
615 SplitCriticalEdge(OldSucc->getTerminator(), i, this);
617 // Since we invalidated the CFG, recalculate the dominator set so that it is
618 // useful for later processing!
619 // FIXME: This is much worse than it really should be!
622 DEBUG(std::cerr << "After forwarding: " << *BB->getParent());
625 /// ReplaceUsesOfValueInRegion - This method replaces all uses of Orig with uses
626 /// of New. It only affects instructions that are defined in basic blocks that
627 /// are dominated by Head.
629 void CEE::ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
630 BasicBlock *RegionDominator) {
631 assert(Orig != New && "Cannot replace value with itself");
632 std::vector<Instruction*> InstsToChange;
633 std::vector<PHINode*> PHIsToChange;
634 InstsToChange.reserve(Orig->use_size());
636 // Loop over instructions adding them to InstsToChange vector, this allows us
637 // an easy way to avoid invalidating the use_iterator at a bad time.
638 for (Value::use_iterator I = Orig->use_begin(), E = Orig->use_end();
640 if (Instruction *User = dyn_cast<Instruction>(*I))
641 if (DS->dominates(RegionDominator, User->getParent()))
642 InstsToChange.push_back(User);
643 else if (PHINode *PN = dyn_cast<PHINode>(User)) {
644 PHIsToChange.push_back(PN);
647 // PHIsToChange contains PHI nodes that use Orig that do not live in blocks
648 // dominated by orig. If the block the value flows in from is dominated by
649 // RegionDominator, then we rewrite the PHI
650 for (unsigned i = 0, e = PHIsToChange.size(); i != e; ++i) {
651 PHINode *PN = PHIsToChange[i];
652 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
653 if (PN->getIncomingValue(j) == Orig &&
654 DS->dominates(RegionDominator, PN->getIncomingBlock(j)))
655 PN->setIncomingValue(j, New);
658 // Loop over the InstsToChange list, replacing all uses of Orig with uses of
659 // New. This list contains all of the instructions in our region that use
661 for (unsigned i = 0, e = InstsToChange.size(); i != e; ++i)
662 if (PHINode *PN = dyn_cast<PHINode>(InstsToChange[i])) {
663 // PHINodes must be handled carefully. If the PHI node itself is in the
664 // region, we have to make sure to only do the replacement for incoming
665 // values that correspond to basic blocks in the region.
666 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
667 if (PN->getIncomingValue(j) == Orig &&
668 DS->dominates(RegionDominator, PN->getIncomingBlock(j)))
669 PN->setIncomingValue(j, New);
672 InstsToChange[i]->replaceUsesOfWith(Orig, New);
676 static void CalcRegionExitBlocks(BasicBlock *Header, BasicBlock *BB,
677 std::set<BasicBlock*> &Visited,
679 std::vector<BasicBlock*> &RegionExitBlocks) {
680 if (Visited.count(BB)) return;
683 if (DS.dominates(Header, BB)) { // Block in the region, recursively traverse
684 for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
685 CalcRegionExitBlocks(Header, *I, Visited, DS, RegionExitBlocks);
687 // Header does not dominate this block, but we have a predecessor that does
688 // dominate us. Add ourself to the list.
689 RegionExitBlocks.push_back(BB);
693 /// CalculateRegionExitBlocks - Find all of the blocks that are not dominated by
694 /// BB, but have predecessors that are. Additionally, prune down the set to
695 /// only include blocks that are dominated by OldSucc as well.
697 void CEE::CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
698 std::vector<BasicBlock*> &RegionExitBlocks){
699 std::set<BasicBlock*> Visited; // Don't infinite loop
701 // Recursively calculate blocks we are interested in...
702 CalcRegionExitBlocks(BB, BB, Visited, *DS, RegionExitBlocks);
704 // Filter out blocks that are not dominated by OldSucc...
705 for (unsigned i = 0; i != RegionExitBlocks.size(); ) {
706 if (DS->dominates(OldSucc, RegionExitBlocks[i]))
707 ++i; // Block is ok, keep it.
709 // Move to end of list...
710 std::swap(RegionExitBlocks[i], RegionExitBlocks.back());
711 RegionExitBlocks.pop_back(); // Nuke the end
716 void CEE::InsertRegionExitMerges(PHINode *BBVal, Instruction *OldVal,
717 const std::vector<BasicBlock*> &RegionExitBlocks) {
718 assert(BBVal->getType() == OldVal->getType() && "Should be derived values!");
719 BasicBlock *BB = BBVal->getParent();
720 BasicBlock *OldSucc = OldVal->getParent();
722 // Loop over all of the blocks we have to place PHIs in, doing it.
723 for (unsigned i = 0, e = RegionExitBlocks.size(); i != e; ++i) {
724 BasicBlock *FBlock = RegionExitBlocks[i]; // Block on the frontier
726 // Create the new PHI node
727 PHINode *NewPN = new PHINode(BBVal->getType(),
728 OldVal->getName()+".fw_frontier",
731 // Add an incoming value for every predecessor of the block...
732 for (pred_iterator PI = pred_begin(FBlock), PE = pred_end(FBlock);
734 // If the incoming edge is from the region dominated by BB, use BBVal,
735 // otherwise use OldVal.
736 NewPN->addIncoming(DS->dominates(BB, *PI) ? BBVal : OldVal, *PI);
739 // Now make everyone dominated by this block use this new value!
740 ReplaceUsesOfValueInRegion(OldVal, NewPN, FBlock);
746 // BuildRankMap - This method builds the rank map data structure which gives
747 // each instruction/value in the function a value based on how early it appears
748 // in the function. We give constants and globals rank 0, arguments are
749 // numbered starting at one, and instructions are numbered in reverse post-order
750 // from where the arguments leave off. This gives instructions in loops higher
751 // values than instructions not in loops.
753 void CEE::BuildRankMap(Function &F) {
754 unsigned Rank = 1; // Skip rank zero.
756 // Number the arguments...
757 for (Function::aiterator I = F.abegin(), E = F.aend(); I != E; ++I)
760 // Number the instructions in reverse post order...
761 ReversePostOrderTraversal<Function*> RPOT(&F);
762 for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
763 E = RPOT.end(); I != E; ++I)
764 for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end();
766 if (BBI->getType() != Type::VoidTy)
767 RankMap[BBI] = Rank++;
771 // PropagateBranchInfo - When this method is invoked, we need to propagate
772 // information derived from the branch condition into the true and false
773 // branches of BI. Since we know that there aren't any critical edges in the
774 // flow graph, this can proceed unconditionally.
776 void CEE::PropagateBranchInfo(BranchInst *BI) {
777 assert(BI->isConditional() && "Must be a conditional branch!");
779 // Propagate information into the true block...
781 PropagateEquality(BI->getCondition(), ConstantBool::True,
782 getRegionInfo(BI->getSuccessor(0)));
784 // Propagate information into the false block...
786 PropagateEquality(BI->getCondition(), ConstantBool::False,
787 getRegionInfo(BI->getSuccessor(1)));
791 // PropagateEquality - If we discover that two values are equal to each other in
792 // a specified region, propagate this knowledge recursively.
794 void CEE::PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI) {
795 if (Op0 == Op1) return; // Gee whiz. Are these really equal each other?
797 if (isa<Constant>(Op0)) // Make sure the constant is always Op1
800 // Make sure we don't already know these are equal, to avoid infinite loops...
801 ValueInfo &VI = RI.getValueInfo(Op0);
803 // Get information about the known relationship between Op0 & Op1
804 Relation &KnownRelation = VI.getRelation(Op1);
806 // If we already know they're equal, don't reprocess...
807 if (KnownRelation.getRelation() == Instruction::SetEQ)
810 // If this is boolean, check to see if one of the operands is a constant. If
811 // it's a constant, then see if the other one is one of a setcc instruction,
812 // an AND, OR, or XOR instruction.
814 if (ConstantBool *CB = dyn_cast<ConstantBool>(Op1)) {
816 if (Instruction *Inst = dyn_cast<Instruction>(Op0)) {
817 // If we know that this instruction is an AND instruction, and the result
818 // is true, this means that both operands to the OR are known to be true
821 if (CB->getValue() && Inst->getOpcode() == Instruction::And) {
822 PropagateEquality(Inst->getOperand(0), CB, RI);
823 PropagateEquality(Inst->getOperand(1), CB, RI);
826 // If we know that this instruction is an OR instruction, and the result
827 // is false, this means that both operands to the OR are know to be false
830 if (!CB->getValue() && Inst->getOpcode() == Instruction::Or) {
831 PropagateEquality(Inst->getOperand(0), CB, RI);
832 PropagateEquality(Inst->getOperand(1), CB, RI);
835 // If we know that this instruction is a NOT instruction, we know that the
836 // operand is known to be the inverse of whatever the current value is.
838 if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(Inst))
839 if (BinaryOperator::isNot(BOp))
840 PropagateEquality(BinaryOperator::getNotArgument(BOp),
841 ConstantBool::get(!CB->getValue()), RI);
843 // If we know the value of a SetCC instruction, propagate the information
844 // about the relation into this region as well.
846 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Inst)) {
847 if (CB->getValue()) { // If we know the condition is true...
848 // Propagate info about the LHS to the RHS & RHS to LHS
849 PropagateRelation(SCI->getOpcode(), SCI->getOperand(0),
850 SCI->getOperand(1), RI);
851 PropagateRelation(SCI->getSwappedCondition(),
852 SCI->getOperand(1), SCI->getOperand(0), RI);
854 } else { // If we know the condition is false...
855 // We know the opposite of the condition is true...
856 Instruction::BinaryOps C = SCI->getInverseCondition();
858 PropagateRelation(C, SCI->getOperand(0), SCI->getOperand(1), RI);
859 PropagateRelation(SetCondInst::getSwappedCondition(C),
860 SCI->getOperand(1), SCI->getOperand(0), RI);
866 // Propagate information about Op0 to Op1 & visa versa
867 PropagateRelation(Instruction::SetEQ, Op0, Op1, RI);
868 PropagateRelation(Instruction::SetEQ, Op1, Op0, RI);
872 // PropagateRelation - We know that the specified relation is true in all of the
873 // blocks in the specified region. Propagate the information about Op0 and
874 // anything derived from it into this region.
876 void CEE::PropagateRelation(Instruction::BinaryOps Opcode, Value *Op0,
877 Value *Op1, RegionInfo &RI) {
878 assert(Op0->getType() == Op1->getType() && "Equal types expected!");
880 // Constants are already pretty well understood. We will apply information
881 // about the constant to Op1 in another call to PropagateRelation.
883 if (isa<Constant>(Op0)) return;
885 // Get the region information for this block to update...
886 ValueInfo &VI = RI.getValueInfo(Op0);
888 // Get information about the known relationship between Op0 & Op1
889 Relation &Op1R = VI.getRelation(Op1);
891 // Quick bailout for common case if we are reprocessing an instruction...
892 if (Op1R.getRelation() == Opcode)
895 // If we already have information that contradicts the current information we
896 // are propagating, ignore this info. Something bad must have happened!
898 if (Op1R.contradicts(Opcode, VI)) {
899 Op1R.contradicts(Opcode, VI);
900 std::cerr << "Contradiction found for opcode: "
901 << Instruction::getOpcodeName(Opcode) << "\n";
902 Op1R.print(std::cerr);
906 // If the information propagated is new, then we want process the uses of this
907 // instruction to propagate the information down to them.
909 if (Op1R.incorporate(Opcode, VI))
910 UpdateUsersOfValue(Op0, RI);
914 // UpdateUsersOfValue - The information about V in this region has been updated.
915 // Propagate this to all consumers of the value.
917 void CEE::UpdateUsersOfValue(Value *V, RegionInfo &RI) {
918 for (Value::use_iterator I = V->use_begin(), E = V->use_end();
920 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
921 // If this is an instruction using a value that we know something about,
922 // try to propagate information to the value produced by the
923 // instruction. We can only do this if it is an instruction we can
924 // propagate information for (a setcc for example), and we only WANT to
925 // do this if the instruction dominates this region.
927 // If the instruction doesn't dominate this region, then it cannot be
928 // used in this region and we don't care about it. If the instruction
929 // is IN this region, then we will simplify the instruction before we
930 // get to uses of it anyway, so there is no reason to bother with it
931 // here. This check is also effectively checking to make sure that Inst
932 // is in the same function as our region (in case V is a global f.e.).
934 if (DS->properlyDominates(Inst->getParent(), RI.getEntryBlock()))
935 IncorporateInstruction(Inst, RI);
939 // IncorporateInstruction - We just updated the information about one of the
940 // operands to the specified instruction. Update the information about the
941 // value produced by this instruction
943 void CEE::IncorporateInstruction(Instruction *Inst, RegionInfo &RI) {
944 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Inst)) {
945 // See if we can figure out a result for this instruction...
946 Relation::KnownResult Result = getSetCCResult(SCI, RI);
947 if (Result != Relation::Unknown) {
948 PropagateEquality(SCI, Result ? ConstantBool::True : ConstantBool::False,
955 // ComputeReplacements - Some values are known to be equal to other values in a
956 // region. For example if there is a comparison of equality between a variable
957 // X and a constant C, we can replace all uses of X with C in the region we are
958 // interested in. We generalize this replacement to replace variables with
959 // other variables if they are equal and there is a variable with lower rank
960 // than the current one. This offers a canonicalizing property that exposes
961 // more redundancies for later transformations to take advantage of.
963 void CEE::ComputeReplacements(RegionInfo &RI) {
964 // Loop over all of the values in the region info map...
965 for (RegionInfo::iterator I = RI.begin(), E = RI.end(); I != E; ++I) {
966 ValueInfo &VI = I->second;
968 // If we know that this value is a particular constant, set Replacement to
970 Value *Replacement = VI.getBounds().getSingleElement();
972 // If this value is not known to be some constant, figure out the lowest
973 // rank value that it is known to be equal to (if anything).
975 if (Replacement == 0) {
976 // Find out if there are any equality relationships with values of lower
977 // rank than VI itself...
978 unsigned MinRank = getRank(I->first);
980 // Loop over the relationships known about Op0.
981 const std::vector<Relation> &Relationships = VI.getRelationships();
982 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
983 if (Relationships[i].getRelation() == Instruction::SetEQ) {
984 unsigned R = getRank(Relationships[i].getValue());
987 Replacement = Relationships[i].getValue();
992 // If we found something to replace this value with, keep track of it.
994 VI.setReplacement(Replacement);
998 // SimplifyBasicBlock - Given information about values in region RI, simplify
999 // the instructions in the specified basic block.
1001 bool CEE::SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI) {
1002 bool Changed = false;
1003 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ) {
1004 Instruction *Inst = I++;
1006 // Convert instruction arguments to canonical forms...
1007 Changed |= SimplifyInstruction(Inst, RI);
1009 if (SetCondInst *SCI = dyn_cast<SetCondInst>(Inst)) {
1010 // Try to simplify a setcc instruction based on inherited information
1011 Relation::KnownResult Result = getSetCCResult(SCI, RI);
1012 if (Result != Relation::Unknown) {
1013 DEBUG(std::cerr << "Replacing setcc with " << Result
1014 << " constant: " << SCI);
1016 SCI->replaceAllUsesWith(ConstantBool::get((bool)Result));
1017 // The instruction is now dead, remove it from the program.
1018 SCI->getParent()->getInstList().erase(SCI);
1028 // SimplifyInstruction - Inspect the operands of the instruction, converting
1029 // them to their canonical form if possible. This takes care of, for example,
1030 // replacing a value 'X' with a constant 'C' if the instruction in question is
1031 // dominated by a true seteq 'X', 'C'.
1033 bool CEE::SimplifyInstruction(Instruction *I, const RegionInfo &RI) {
1034 bool Changed = false;
1036 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1037 if (const ValueInfo *VI = RI.requestValueInfo(I->getOperand(i)))
1038 if (Value *Repl = VI->getReplacement()) {
1039 // If we know if a replacement with lower rank than Op0, make the
1041 DEBUG(std::cerr << "In Inst: " << I << " Replacing operand #" << i
1042 << " with " << Repl << "\n");
1043 I->setOperand(i, Repl);
1052 // getSetCCResult - Try to simplify a setcc instruction based on information
1053 // inherited from a dominating setcc instruction. V is one of the operands to
1054 // the setcc instruction, and VI is the set of information known about it. We
1055 // take two cases into consideration here. If the comparison is against a
1056 // constant value, we can use the constant range to see if the comparison is
1057 // possible to succeed. If it is not a comparison against a constant, we check
1058 // to see if there is a known relationship between the two values. If so, we
1059 // may be able to eliminate the check.
1061 Relation::KnownResult CEE::getSetCCResult(SetCondInst *SCI,
1062 const RegionInfo &RI) {
1063 Value *Op0 = SCI->getOperand(0), *Op1 = SCI->getOperand(1);
1064 Instruction::BinaryOps Opcode = SCI->getOpcode();
1066 if (isa<Constant>(Op0)) {
1067 if (isa<Constant>(Op1)) {
1068 if (Constant *Result = ConstantFoldInstruction(SCI)) {
1069 // Wow, this is easy, directly eliminate the SetCondInst.
1070 DEBUG(std::cerr << "Replacing setcc with constant fold: " << SCI);
1071 return cast<ConstantBool>(Result)->getValue()
1072 ? Relation::KnownTrue : Relation::KnownFalse;
1075 // We want to swap this instruction so that operand #0 is the constant.
1076 std::swap(Op0, Op1);
1077 Opcode = SCI->getSwappedCondition();
1081 // Try to figure out what the result of this comparison will be...
1082 Relation::KnownResult Result = Relation::Unknown;
1084 // We have to know something about the relationship to prove anything...
1085 if (const ValueInfo *Op0VI = RI.requestValueInfo(Op0)) {
1087 // At this point, we know that if we have a constant argument that it is in
1088 // Op1. Check to see if we know anything about comparing value with a
1089 // constant, and if we can use this info to fold the setcc.
1091 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(Op1)) {
1092 // Check to see if we already know the result of this comparison...
1093 ConstantRange R = ConstantRange(Opcode, C);
1094 ConstantRange Int = R.intersectWith(Op0VI->getBounds());
1096 // If the intersection of the two ranges is empty, then the condition
1097 // could never be true!
1099 if (Int.isEmptySet()) {
1100 Result = Relation::KnownFalse;
1102 // Otherwise, if VI.getBounds() (the possible values) is a subset of R
1103 // (the allowed values) then we know that the condition must always be
1106 } else if (Int == Op0VI->getBounds()) {
1107 Result = Relation::KnownTrue;
1110 // If we are here, we know that the second argument is not a constant
1111 // integral. See if we know anything about Op0 & Op1 that allows us to
1112 // fold this anyway.
1114 // Do we have value information about Op0 and a relation to Op1?
1115 if (const Relation *Op2R = Op0VI->requestRelation(Op1))
1116 Result = Op2R->getImpliedResult(Opcode);
1122 //===----------------------------------------------------------------------===//
1123 // Relation Implementation
1124 //===----------------------------------------------------------------------===//
1126 // CheckCondition - Return true if the specified condition is false. Bound may
1128 static bool CheckCondition(Constant *Bound, Constant *C,
1129 Instruction::BinaryOps BO) {
1130 assert(C != 0 && "C is not specified!");
1131 if (Bound == 0) return false;
1135 default: assert(0 && "Unknown Condition code!");
1136 case Instruction::SetEQ: Val = *Bound == *C; break;
1137 case Instruction::SetNE: Val = *Bound != *C; break;
1138 case Instruction::SetLT: Val = *Bound < *C; break;
1139 case Instruction::SetGT: Val = *Bound > *C; break;
1140 case Instruction::SetLE: Val = *Bound <= *C; break;
1141 case Instruction::SetGE: Val = *Bound >= *C; break;
1144 // ConstantHandling code may not succeed in the comparison...
1145 if (Val == 0) return false;
1146 return !Val->getValue(); // Return true if the condition is false...
1149 // contradicts - Return true if the relationship specified by the operand
1150 // contradicts already known information.
1152 bool Relation::contradicts(Instruction::BinaryOps Op,
1153 const ValueInfo &VI) const {
1154 assert (Op != Instruction::Add && "Invalid relation argument!");
1156 // If this is a relationship with a constant, make sure that this relationship
1157 // does not contradict properties known about the bounds of the constant.
1159 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(Val))
1160 if (ConstantRange(Op, C).intersectWith(VI.getBounds()).isEmptySet())
1164 default: assert(0 && "Unknown Relationship code!");
1165 case Instruction::Add: return false; // Nothing known, nothing contradicts
1166 case Instruction::SetEQ:
1167 return Op == Instruction::SetLT || Op == Instruction::SetGT ||
1168 Op == Instruction::SetNE;
1169 case Instruction::SetNE: return Op == Instruction::SetEQ;
1170 case Instruction::SetLE: return Op == Instruction::SetGT;
1171 case Instruction::SetGE: return Op == Instruction::SetLT;
1172 case Instruction::SetLT:
1173 return Op == Instruction::SetEQ || Op == Instruction::SetGT ||
1174 Op == Instruction::SetGE;
1175 case Instruction::SetGT:
1176 return Op == Instruction::SetEQ || Op == Instruction::SetLT ||
1177 Op == Instruction::SetLE;
1181 // incorporate - Incorporate information in the argument into this relation
1182 // entry. This assumes that the information doesn't contradict itself. If any
1183 // new information is gained, true is returned, otherwise false is returned to
1184 // indicate that nothing was updated.
1186 bool Relation::incorporate(Instruction::BinaryOps Op, ValueInfo &VI) {
1187 assert(!contradicts(Op, VI) &&
1188 "Cannot incorporate contradictory information!");
1190 // If this is a relationship with a constant, make sure that we update the
1191 // range that is possible for the value to have...
1193 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(Val))
1194 VI.getBounds() = ConstantRange(Op, C).intersectWith(VI.getBounds());
1197 default: assert(0 && "Unknown prior value!");
1198 case Instruction::Add: Rel = Op; return true;
1199 case Instruction::SetEQ: return false; // Nothing is more precise
1200 case Instruction::SetNE: return false; // Nothing is more precise
1201 case Instruction::SetLT: return false; // Nothing is more precise
1202 case Instruction::SetGT: return false; // Nothing is more precise
1203 case Instruction::SetLE:
1204 if (Op == Instruction::SetEQ || Op == Instruction::SetLT) {
1207 } else if (Op == Instruction::SetNE) {
1208 Rel = Instruction::SetLT;
1212 case Instruction::SetGE: return Op == Instruction::SetLT;
1213 if (Op == Instruction::SetEQ || Op == Instruction::SetGT) {
1216 } else if (Op == Instruction::SetNE) {
1217 Rel = Instruction::SetGT;
1224 // getImpliedResult - If this relationship between two values implies that
1225 // the specified relationship is true or false, return that. If we cannot
1226 // determine the result required, return Unknown.
1228 Relation::KnownResult
1229 Relation::getImpliedResult(Instruction::BinaryOps Op) const {
1230 if (Rel == Op) return KnownTrue;
1231 if (Rel == SetCondInst::getInverseCondition(Op)) return KnownFalse;
1234 default: assert(0 && "Unknown prior value!");
1235 case Instruction::SetEQ:
1236 if (Op == Instruction::SetLE || Op == Instruction::SetGE) return KnownTrue;
1237 if (Op == Instruction::SetLT || Op == Instruction::SetGT) return KnownFalse;
1239 case Instruction::SetLT:
1240 if (Op == Instruction::SetNE || Op == Instruction::SetLE) return KnownTrue;
1241 if (Op == Instruction::SetEQ) return KnownFalse;
1243 case Instruction::SetGT:
1244 if (Op == Instruction::SetNE || Op == Instruction::SetGE) return KnownTrue;
1245 if (Op == Instruction::SetEQ) return KnownFalse;
1247 case Instruction::SetNE:
1248 case Instruction::SetLE:
1249 case Instruction::SetGE:
1250 case Instruction::Add:
1257 //===----------------------------------------------------------------------===//
1258 // Printing Support...
1259 //===----------------------------------------------------------------------===//
1261 // print - Implement the standard print form to print out analysis information.
1262 void CEE::print(std::ostream &O, const Module *M) const {
1263 O << "\nPrinting Correlated Expression Info:\n";
1264 for (std::map<BasicBlock*, RegionInfo>::const_iterator I =
1265 RegionInfoMap.begin(), E = RegionInfoMap.end(); I != E; ++I)
1269 // print - Output information about this region...
1270 void RegionInfo::print(std::ostream &OS) const {
1271 if (ValueMap.empty()) return;
1273 OS << " RegionInfo for basic block: " << BB->getName() << "\n";
1274 for (std::map<Value*, ValueInfo>::const_iterator
1275 I = ValueMap.begin(), E = ValueMap.end(); I != E; ++I)
1276 I->second.print(OS, I->first);
1280 // print - Output information about this value relation...
1281 void ValueInfo::print(std::ostream &OS, Value *V) const {
1282 if (Relationships.empty()) return;
1285 OS << " ValueInfo for: ";
1286 WriteAsOperand(OS, V);
1288 OS << "\n Bounds = " << Bounds << "\n";
1290 OS << " Replacement = ";
1291 WriteAsOperand(OS, Replacement);
1294 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
1295 Relationships[i].print(OS);
1298 // print - Output this relation to the specified stream
1299 void Relation::print(std::ostream &OS) const {
1302 default: OS << "*UNKNOWN*"; break;
1303 case Instruction::SetEQ: OS << "== "; break;
1304 case Instruction::SetNE: OS << "!= "; break;
1305 case Instruction::SetLT: OS << "< "; break;
1306 case Instruction::SetGT: OS << "> "; break;
1307 case Instruction::SetLE: OS << "<= "; break;
1308 case Instruction::SetGE: OS << ">= "; break;
1311 WriteAsOperand(OS, Val);
1315 // Don't inline these methods or else we won't be able to call them from GDB!
1316 void Relation::dump() const { print(std::cerr); }
1317 void ValueInfo::dump() const { print(std::cerr, 0); }
1318 void RegionInfo::dump() const { print(std::cerr); }