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 #define DEBUG_TYPE "cee"
30 #include "llvm/Transforms/Scalar.h"
31 #include "llvm/Constants.h"
32 #include "llvm/Pass.h"
33 #include "llvm/Function.h"
34 #include "llvm/Instructions.h"
35 #include "llvm/Type.h"
36 #include "llvm/DerivedTypes.h"
37 #include "llvm/Analysis/ConstantFolding.h"
38 #include "llvm/Analysis/Dominators.h"
39 #include "llvm/Assembly/Writer.h"
40 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
41 #include "llvm/Support/CFG.h"
42 #include "llvm/Support/Compiler.h"
43 #include "llvm/Support/ConstantRange.h"
44 #include "llvm/Support/Debug.h"
45 #include "llvm/ADT/PostOrderIterator.h"
46 #include "llvm/ADT/Statistic.h"
50 STATISTIC(NumCmpRemoved, "Number of cmp instruction eliminated");
51 STATISTIC(NumOperandsCann, "Number of operands canonicalized");
52 STATISTIC(BranchRevectors, "Number of branches revectored");
56 class VISIBILITY_HIDDEN Relation {
57 Value *Val; // Relation to what value?
58 unsigned Rel; // SetCC or ICmp relation, or Add if no information
60 Relation(Value *V) : Val(V), Rel(Instruction::Add) {}
61 bool operator<(const Relation &R) const { return Val < R.Val; }
62 Value *getValue() const { return Val; }
63 unsigned getRelation() const { return Rel; }
65 // contradicts - Return true if the relationship specified by the operand
66 // contradicts already known information.
68 bool contradicts(unsigned Rel, const ValueInfo &VI) const;
70 // incorporate - Incorporate information in the argument into this relation
71 // entry. This assumes that the information doesn't contradict itself. If
72 // any new information is gained, true is returned, otherwise false is
73 // returned to indicate that nothing was updated.
75 bool incorporate(unsigned Rel, ValueInfo &VI);
77 // KnownResult - Whether or not this condition determines the result of a
78 // setcc or icmp in the program. False & True are intentionally 0 & 1
79 // so we can convert to bool by casting after checking for unknown.
81 enum KnownResult { KnownFalse = 0, KnownTrue = 1, Unknown = 2 };
83 // getImpliedResult - If this relationship between two values implies that
84 // the specified relationship is true or false, return that. If we cannot
85 // determine the result required, return Unknown.
87 KnownResult getImpliedResult(unsigned Rel) const;
89 // print - Output this relation to the specified stream
90 void print(std::ostream &OS) const;
95 // ValueInfo - One instance of this record exists for every value with
96 // relationships between other values. It keeps track of all of the
97 // relationships to other values in the program (specified with Relation) that
98 // are known to be valid in a region.
100 class VISIBILITY_HIDDEN ValueInfo {
101 // RelationShips - this value is know to have the specified relationships to
102 // other values. There can only be one entry per value, and this list is
103 // kept sorted by the Val field.
104 std::vector<Relation> Relationships;
106 // If information about this value is known or propagated from constant
107 // expressions, this range contains the possible values this value may hold.
108 ConstantRange Bounds;
110 // If we find that this value is equal to another value that has a lower
111 // rank, this value is used as it's replacement.
115 ValueInfo(const Type *Ty)
116 : Bounds(Ty->isInteger() ? cast<IntegerType>(Ty)->getBitWidth() : 32),
119 // getBounds() - Return the constant bounds of the value...
120 const ConstantRange &getBounds() const { return Bounds; }
121 ConstantRange &getBounds() { return Bounds; }
123 const std::vector<Relation> &getRelationships() { return Relationships; }
125 // getReplacement - Return the value this value is to be replaced with if it
126 // exists, otherwise return null.
128 Value *getReplacement() const { return Replacement; }
130 // setReplacement - Used by the replacement calculation pass to figure out
131 // what to replace this value with, if anything.
133 void setReplacement(Value *Repl) { Replacement = Repl; }
135 // getRelation - return the relationship entry for the specified value.
136 // This can invalidate references to other Relations, so use it carefully.
138 Relation &getRelation(Value *V) {
139 // Binary search for V's entry...
140 std::vector<Relation>::iterator I =
141 std::lower_bound(Relationships.begin(), Relationships.end(),
144 // If we found the entry, return it...
145 if (I != Relationships.end() && I->getValue() == V)
148 // Insert and return the new relationship...
149 return *Relationships.insert(I, V);
152 const Relation *requestRelation(Value *V) const {
153 // Binary search for V's entry...
154 std::vector<Relation>::const_iterator I =
155 std::lower_bound(Relationships.begin(), Relationships.end(),
157 if (I != Relationships.end() && I->getValue() == V)
162 // print - Output information about this value relation...
163 void print(std::ostream &OS, Value *V) const;
167 // RegionInfo - Keeps track of all of the value relationships for a region. A
168 // region is the are dominated by a basic block. RegionInfo's keep track of
169 // the RegionInfo for their dominator, because anything known in a dominator
170 // is known to be true in a dominated block as well.
172 class VISIBILITY_HIDDEN RegionInfo {
175 // ValueMap - Tracks the ValueInformation known for this region
176 typedef std::map<Value*, ValueInfo> ValueMapTy;
179 RegionInfo(BasicBlock *bb) : BB(bb) {}
181 // getEntryBlock - Return the block that dominates all of the members of
183 BasicBlock *getEntryBlock() const { return BB; }
185 // empty - return true if this region has no information known about it.
186 bool empty() const { return ValueMap.empty(); }
188 const RegionInfo &operator=(const RegionInfo &RI) {
189 ValueMap = RI.ValueMap;
193 // print - Output information about this region...
194 void print(std::ostream &OS) const;
197 // Allow external access.
198 typedef ValueMapTy::iterator iterator;
199 iterator begin() { return ValueMap.begin(); }
200 iterator end() { return ValueMap.end(); }
202 ValueInfo &getValueInfo(Value *V) {
203 ValueMapTy::iterator I = ValueMap.lower_bound(V);
204 if (I != ValueMap.end() && I->first == V) return I->second;
205 return ValueMap.insert(I, std::make_pair(V, V->getType()))->second;
208 const ValueInfo *requestValueInfo(Value *V) const {
209 ValueMapTy::const_iterator I = ValueMap.find(V);
210 if (I != ValueMap.end()) return &I->second;
214 /// removeValueInfo - Remove anything known about V from our records. This
215 /// works whether or not we know anything about V.
217 void removeValueInfo(Value *V) {
222 /// CEE - Correlated Expression Elimination
223 class VISIBILITY_HIDDEN CEE : public FunctionPass {
224 std::map<Value*, unsigned> RankMap;
225 std::map<BasicBlock*, RegionInfo> RegionInfoMap;
229 virtual bool runOnFunction(Function &F);
231 // We don't modify the program, so we preserve all analyses
232 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
233 AU.addRequired<ETForest>();
234 AU.addRequired<DominatorTree>();
235 AU.addRequiredID(BreakCriticalEdgesID);
238 // print - Implement the standard print form to print out analysis
240 virtual void print(std::ostream &O, const Module *M) const;
243 RegionInfo &getRegionInfo(BasicBlock *BB) {
244 std::map<BasicBlock*, RegionInfo>::iterator I
245 = RegionInfoMap.lower_bound(BB);
246 if (I != RegionInfoMap.end() && I->first == BB) return I->second;
247 return RegionInfoMap.insert(I, std::make_pair(BB, BB))->second;
250 void BuildRankMap(Function &F);
251 unsigned getRank(Value *V) const {
252 if (isa<Constant>(V)) return 0;
253 std::map<Value*, unsigned>::const_iterator I = RankMap.find(V);
254 if (I != RankMap.end()) return I->second;
255 return 0; // Must be some other global thing
258 bool TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks);
260 bool ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
263 void ForwardSuccessorTo(TerminatorInst *TI, unsigned Succ, BasicBlock *D,
265 void ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
266 BasicBlock *RegionDominator);
267 void CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
268 std::vector<BasicBlock*> &RegionExitBlocks);
269 void InsertRegionExitMerges(PHINode *NewPHI, Instruction *OldVal,
270 const std::vector<BasicBlock*> &RegionExitBlocks);
272 void PropagateBranchInfo(BranchInst *BI);
273 void PropagateSwitchInfo(SwitchInst *SI);
274 void PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI);
275 void PropagateRelation(unsigned Opcode, Value *Op0,
276 Value *Op1, RegionInfo &RI);
277 void UpdateUsersOfValue(Value *V, RegionInfo &RI);
278 void IncorporateInstruction(Instruction *Inst, RegionInfo &RI);
279 void ComputeReplacements(RegionInfo &RI);
281 // getCmpResult - Given a icmp instruction, determine if the result is
282 // determined by facts we already know about the region under analysis.
283 // Return KnownTrue, KnownFalse, or UnKnown based on what we can determine.
284 Relation::KnownResult getCmpResult(CmpInst *ICI, const RegionInfo &RI);
286 bool SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI);
287 bool SimplifyInstruction(Instruction *Inst, const RegionInfo &RI);
289 RegisterPass<CEE> X("cee", "Correlated Expression Elimination");
292 FunctionPass *llvm::createCorrelatedExpressionEliminationPass() {
297 bool CEE::runOnFunction(Function &F) {
298 // Build a rank map for the function...
301 // Traverse the dominator tree, computing information for each node in the
302 // tree. Note that our traversal will not even touch unreachable basic
304 EF = &getAnalysis<ETForest>();
305 DT = &getAnalysis<DominatorTree>();
307 std::set<BasicBlock*> VisitedBlocks;
308 bool Changed = TransformRegion(&F.getEntryBlock(), VisitedBlocks);
310 RegionInfoMap.clear();
315 // TransformRegion - Transform the region starting with BB according to the
316 // calculated region information for the block. Transforming the region
317 // involves analyzing any information this block provides to successors,
318 // propagating the information to successors, and finally transforming
321 // This method processes the function in depth first order, which guarantees
322 // that we process the immediate dominator of a block before the block itself.
323 // Because we are passing information from immediate dominators down to
324 // dominatees, we obviously have to process the information source before the
325 // information consumer.
327 bool CEE::TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks){
328 // Prevent infinite recursion...
329 if (VisitedBlocks.count(BB)) return false;
330 VisitedBlocks.insert(BB);
332 // Get the computed region information for this block...
333 RegionInfo &RI = getRegionInfo(BB);
335 // Compute the replacement information for this block...
336 ComputeReplacements(RI);
338 // If debugging, print computed region information...
339 DEBUG(RI.print(*cerr.stream()));
341 // Simplify the contents of this block...
342 bool Changed = SimplifyBasicBlock(*BB, RI);
344 // Get the terminator of this basic block...
345 TerminatorInst *TI = BB->getTerminator();
347 // Loop over all of the blocks that this block is the immediate dominator for.
348 // Because all information known in this region is also known in all of the
349 // blocks that are dominated by this one, we can safely propagate the
350 // information down now.
352 DominatorTree::Node *BBN = (*DT)[BB];
353 if (!RI.empty()) // Time opt: only propagate if we can change something
354 for (unsigned i = 0, e = BBN->getChildren().size(); i != e; ++i) {
355 BasicBlock *Dominated = BBN->getChildren()[i]->getBlock();
356 assert(RegionInfoMap.find(Dominated) == RegionInfoMap.end() &&
357 "RegionInfo should be calculated in dominanace order!");
358 getRegionInfo(Dominated) = RI;
361 // Now that all of our successors have information if they deserve it,
362 // propagate any information our terminator instruction finds to our
364 if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
365 if (BI->isConditional())
366 PropagateBranchInfo(BI);
367 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
368 PropagateSwitchInfo(SI);
371 // If this is a branch to a block outside our region that simply performs
372 // another conditional branch, one whose outcome is known inside of this
373 // region, then vector this outgoing edge directly to the known destination.
375 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
376 while (ForwardCorrelatedEdgeDestination(TI, i, RI)) {
381 // Now that all of our successors have information, recursively process them.
382 for (unsigned i = 0, e = BBN->getChildren().size(); i != e; ++i)
383 Changed |= TransformRegion(BBN->getChildren()[i]->getBlock(),VisitedBlocks);
388 // isBlockSimpleEnoughForCheck to see if the block is simple enough for us to
389 // revector the conditional branch in the bottom of the block, do so now.
391 static bool isBlockSimpleEnough(BasicBlock *BB) {
392 assert(isa<BranchInst>(BB->getTerminator()));
393 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
394 assert(BI->isConditional());
396 // Check the common case first: empty block, or block with just a setcc.
397 if (BB->size() == 1 ||
398 (BB->size() == 2 && &BB->front() == BI->getCondition() &&
399 BI->getCondition()->hasOneUse()))
402 // Check the more complex case now...
403 BasicBlock::iterator I = BB->begin();
405 // FIXME: This should be reenabled once the regression with SIM is fixed!
407 // PHI Nodes are ok, just skip over them...
408 while (isa<PHINode>(*I)) ++I;
411 // Accept the setcc instruction...
412 if (&*I == BI->getCondition())
415 // Nothing else is acceptable here yet. We must not revector... unless we are
416 // at the terminator instruction.
424 bool CEE::ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
426 // If this successor is a simple block not in the current region, which
427 // contains only a conditional branch, we decide if the outcome of the branch
428 // can be determined from information inside of the region. Instead of going
429 // to this block, we can instead go to the destination we know is the right
433 // Check to see if we dominate the block. If so, this block will get the
434 // condition turned to a constant anyway.
436 //if (EF->dominates(RI.getEntryBlock(), BB))
439 BasicBlock *BB = TI->getParent();
441 // Get the destination block of this edge...
442 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
444 // Make sure that the block ends with a conditional branch and is simple
445 // enough for use to be able to revector over.
446 BranchInst *BI = dyn_cast<BranchInst>(OldSucc->getTerminator());
447 if (BI == 0 || !BI->isConditional() || !isBlockSimpleEnough(OldSucc))
450 // We can only forward the branch over the block if the block ends with a
451 // cmp we can determine the outcome for.
453 // FIXME: we can make this more generic. Code below already handles more
455 if (!isa<CmpInst>(BI->getCondition()))
458 // Make a new RegionInfo structure so that we can simulate the effect of the
459 // PHI nodes in the block we are skipping over...
461 RegionInfo NewRI(RI);
463 // Remove value information for all of the values we are simulating... to make
464 // sure we don't have any stale information.
465 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
466 if (I->getType() != Type::VoidTy)
467 NewRI.removeValueInfo(I);
469 // Put the newly discovered information into the RegionInfo...
470 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
471 if (PHINode *PN = dyn_cast<PHINode>(I)) {
472 int OpNum = PN->getBasicBlockIndex(BB);
473 assert(OpNum != -1 && "PHI doesn't have incoming edge for predecessor!?");
474 PropagateEquality(PN, PN->getIncomingValue(OpNum), NewRI);
475 } else if (CmpInst *CI = dyn_cast<CmpInst>(I)) {
476 Relation::KnownResult Res = getCmpResult(CI, NewRI);
477 if (Res == Relation::Unknown) return false;
478 PropagateEquality(CI, ConstantInt::get(Type::Int1Ty, Res), NewRI);
480 assert(isa<BranchInst>(*I) && "Unexpected instruction type!");
483 // Compute the facts implied by what we have discovered...
484 ComputeReplacements(NewRI);
486 ValueInfo &PredicateVI = NewRI.getValueInfo(BI->getCondition());
487 if (PredicateVI.getReplacement() &&
488 isa<Constant>(PredicateVI.getReplacement()) &&
489 !isa<GlobalValue>(PredicateVI.getReplacement())) {
490 ConstantInt *CB = cast<ConstantInt>(PredicateVI.getReplacement());
492 // Forward to the successor that corresponds to the branch we will take.
493 ForwardSuccessorTo(TI, SuccNo,
494 BI->getSuccessor(!CB->getZExtValue()), NewRI);
501 static Value *getReplacementOrValue(Value *V, RegionInfo &RI) {
502 if (const ValueInfo *VI = RI.requestValueInfo(V))
503 if (Value *Repl = VI->getReplacement())
508 /// ForwardSuccessorTo - We have found that we can forward successor # 'SuccNo'
509 /// of Terminator 'TI' to the 'Dest' BasicBlock. This method performs the
510 /// mechanics of updating SSA information and revectoring the branch.
512 void CEE::ForwardSuccessorTo(TerminatorInst *TI, unsigned SuccNo,
513 BasicBlock *Dest, RegionInfo &RI) {
514 // If there are any PHI nodes in the Dest BB, we must duplicate the entry
515 // in the PHI node for the old successor to now include an entry from the
516 // current basic block.
518 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
519 BasicBlock *BB = TI->getParent();
521 DOUT << "Forwarding branch in basic block %" << BB->getName()
522 << " from block %" << OldSucc->getName() << " to block %"
523 << Dest->getName() << "\n"
524 << "Before forwarding: " << *BB->getParent();
526 // Because we know that there cannot be critical edges in the flow graph, and
527 // that OldSucc has multiple outgoing edges, this means that Dest cannot have
528 // multiple incoming edges.
531 pred_iterator DPI = pred_begin(Dest); ++DPI;
532 assert(DPI == pred_end(Dest) && "Critical edge found!!");
535 // Loop over any PHI nodes in the destination, eliminating them, because they
536 // may only have one input.
538 while (PHINode *PN = dyn_cast<PHINode>(&Dest->front())) {
539 assert(PN->getNumIncomingValues() == 1 && "Crit edge found!");
540 // Eliminate the PHI node
541 PN->replaceAllUsesWith(PN->getIncomingValue(0));
542 Dest->getInstList().erase(PN);
545 // If there are values defined in the "OldSucc" basic block, we need to insert
546 // PHI nodes in the regions we are dealing with to emulate them. This can
547 // insert dead phi nodes, but it is more trouble to see if they are used than
548 // to just blindly insert them.
550 if (EF->dominates(OldSucc, Dest)) {
551 // RegionExitBlocks - Find all of the blocks that are not dominated by Dest,
552 // but have predecessors that are. Additionally, prune down the set to only
553 // include blocks that are dominated by OldSucc as well.
555 std::vector<BasicBlock*> RegionExitBlocks;
556 CalculateRegionExitBlocks(Dest, OldSucc, RegionExitBlocks);
558 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end();
560 if (I->getType() != Type::VoidTy) {
561 // Create and insert the PHI node into the top of Dest.
562 PHINode *NewPN = new PHINode(I->getType(), I->getName()+".fw_merge",
564 // There is definitely an edge from OldSucc... add the edge now
565 NewPN->addIncoming(I, OldSucc);
567 // There is also an edge from BB now, add the edge with the calculated
568 // value from the RI.
569 NewPN->addIncoming(getReplacementOrValue(I, RI), BB);
571 // Make everything in the Dest region use the new PHI node now...
572 ReplaceUsesOfValueInRegion(I, NewPN, Dest);
574 // Make sure that exits out of the region dominated by NewPN get PHI
575 // nodes that merge the values as appropriate.
576 InsertRegionExitMerges(NewPN, I, RegionExitBlocks);
580 // If there were PHI nodes in OldSucc, we need to remove the entry for this
581 // edge from the PHI node, and we need to replace any references to the PHI
582 // node with a new value.
584 for (BasicBlock::iterator I = OldSucc->begin(); isa<PHINode>(I); ) {
585 PHINode *PN = cast<PHINode>(I);
587 // Get the value flowing across the old edge and remove the PHI node entry
588 // for this edge: we are about to remove the edge! Don't remove the PHI
589 // node yet though if this is the last edge into it.
590 Value *EdgeValue = PN->removeIncomingValue(BB, false);
592 // Make sure that anything that used to use PN now refers to EdgeValue
593 ReplaceUsesOfValueInRegion(PN, EdgeValue, Dest);
595 // If there is only one value left coming into the PHI node, replace the PHI
596 // node itself with the one incoming value left.
598 if (PN->getNumIncomingValues() == 1) {
599 assert(PN->getNumIncomingValues() == 1);
600 PN->replaceAllUsesWith(PN->getIncomingValue(0));
601 PN->getParent()->getInstList().erase(PN);
602 I = OldSucc->begin();
603 } else if (PN->getNumIncomingValues() == 0) { // Nuke the PHI
604 // If we removed the last incoming value to this PHI, nuke the PHI node
606 PN->replaceAllUsesWith(Constant::getNullValue(PN->getType()));
607 PN->getParent()->getInstList().erase(PN);
608 I = OldSucc->begin();
610 ++I; // Otherwise, move on to the next PHI node
614 // Actually revector the branch now...
615 TI->setSuccessor(SuccNo, Dest);
617 // If we just introduced a critical edge in the flow graph, make sure to break
619 SplitCriticalEdge(TI, SuccNo, this);
621 // Make sure that we don't introduce critical edges from oldsucc now!
622 for (unsigned i = 0, e = OldSucc->getTerminator()->getNumSuccessors();
624 SplitCriticalEdge(OldSucc->getTerminator(), i, this);
626 // Since we invalidated the CFG, recalculate the dominator set so that it is
627 // useful for later processing!
628 // FIXME: This is much worse than it really should be!
631 DOUT << "After forwarding: " << *BB->getParent();
634 /// ReplaceUsesOfValueInRegion - This method replaces all uses of Orig with uses
635 /// of New. It only affects instructions that are defined in basic blocks that
636 /// are dominated by Head.
638 void CEE::ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
639 BasicBlock *RegionDominator) {
640 assert(Orig != New && "Cannot replace value with itself");
641 std::vector<Instruction*> InstsToChange;
642 std::vector<PHINode*> PHIsToChange;
643 InstsToChange.reserve(Orig->getNumUses());
645 // Loop over instructions adding them to InstsToChange vector, this allows us
646 // an easy way to avoid invalidating the use_iterator at a bad time.
647 for (Value::use_iterator I = Orig->use_begin(), E = Orig->use_end();
649 if (Instruction *User = dyn_cast<Instruction>(*I))
650 if (EF->dominates(RegionDominator, User->getParent()))
651 InstsToChange.push_back(User);
652 else if (PHINode *PN = dyn_cast<PHINode>(User)) {
653 PHIsToChange.push_back(PN);
656 // PHIsToChange contains PHI nodes that use Orig that do not live in blocks
657 // dominated by orig. If the block the value flows in from is dominated by
658 // RegionDominator, then we rewrite the PHI
659 for (unsigned i = 0, e = PHIsToChange.size(); i != e; ++i) {
660 PHINode *PN = PHIsToChange[i];
661 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
662 if (PN->getIncomingValue(j) == Orig &&
663 EF->dominates(RegionDominator, PN->getIncomingBlock(j)))
664 PN->setIncomingValue(j, New);
667 // Loop over the InstsToChange list, replacing all uses of Orig with uses of
668 // New. This list contains all of the instructions in our region that use
670 for (unsigned i = 0, e = InstsToChange.size(); i != e; ++i)
671 if (PHINode *PN = dyn_cast<PHINode>(InstsToChange[i])) {
672 // PHINodes must be handled carefully. If the PHI node itself is in the
673 // region, we have to make sure to only do the replacement for incoming
674 // values that correspond to basic blocks in the region.
675 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
676 if (PN->getIncomingValue(j) == Orig &&
677 EF->dominates(RegionDominator, PN->getIncomingBlock(j)))
678 PN->setIncomingValue(j, New);
681 InstsToChange[i]->replaceUsesOfWith(Orig, New);
685 static void CalcRegionExitBlocks(BasicBlock *Header, BasicBlock *BB,
686 std::set<BasicBlock*> &Visited,
688 std::vector<BasicBlock*> &RegionExitBlocks) {
689 if (Visited.count(BB)) return;
692 if (EF.dominates(Header, BB)) { // Block in the region, recursively traverse
693 for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
694 CalcRegionExitBlocks(Header, *I, Visited, EF, RegionExitBlocks);
696 // Header does not dominate this block, but we have a predecessor that does
697 // dominate us. Add ourself to the list.
698 RegionExitBlocks.push_back(BB);
702 /// CalculateRegionExitBlocks - Find all of the blocks that are not dominated by
703 /// BB, but have predecessors that are. Additionally, prune down the set to
704 /// only include blocks that are dominated by OldSucc as well.
706 void CEE::CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
707 std::vector<BasicBlock*> &RegionExitBlocks){
708 std::set<BasicBlock*> Visited; // Don't infinite loop
710 // Recursively calculate blocks we are interested in...
711 CalcRegionExitBlocks(BB, BB, Visited, *EF, RegionExitBlocks);
713 // Filter out blocks that are not dominated by OldSucc...
714 for (unsigned i = 0; i != RegionExitBlocks.size(); ) {
715 if (EF->dominates(OldSucc, RegionExitBlocks[i]))
716 ++i; // Block is ok, keep it.
718 // Move to end of list...
719 std::swap(RegionExitBlocks[i], RegionExitBlocks.back());
720 RegionExitBlocks.pop_back(); // Nuke the end
725 void CEE::InsertRegionExitMerges(PHINode *BBVal, Instruction *OldVal,
726 const std::vector<BasicBlock*> &RegionExitBlocks) {
727 assert(BBVal->getType() == OldVal->getType() && "Should be derived values!");
728 BasicBlock *BB = BBVal->getParent();
730 // Loop over all of the blocks we have to place PHIs in, doing it.
731 for (unsigned i = 0, e = RegionExitBlocks.size(); i != e; ++i) {
732 BasicBlock *FBlock = RegionExitBlocks[i]; // Block on the frontier
734 // Create the new PHI node
735 PHINode *NewPN = new PHINode(BBVal->getType(),
736 OldVal->getName()+".fw_frontier",
739 // Add an incoming value for every predecessor of the block...
740 for (pred_iterator PI = pred_begin(FBlock), PE = pred_end(FBlock);
742 // If the incoming edge is from the region dominated by BB, use BBVal,
743 // otherwise use OldVal.
744 NewPN->addIncoming(EF->dominates(BB, *PI) ? BBVal : OldVal, *PI);
747 // Now make everyone dominated by this block use this new value!
748 ReplaceUsesOfValueInRegion(OldVal, NewPN, FBlock);
754 // BuildRankMap - This method builds the rank map data structure which gives
755 // each instruction/value in the function a value based on how early it appears
756 // in the function. We give constants and globals rank 0, arguments are
757 // numbered starting at one, and instructions are numbered in reverse post-order
758 // from where the arguments leave off. This gives instructions in loops higher
759 // values than instructions not in loops.
761 void CEE::BuildRankMap(Function &F) {
762 unsigned Rank = 1; // Skip rank zero.
764 // Number the arguments...
765 for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
768 // Number the instructions in reverse post order...
769 ReversePostOrderTraversal<Function*> RPOT(&F);
770 for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
771 E = RPOT.end(); I != E; ++I)
772 for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end();
774 if (BBI->getType() != Type::VoidTy)
775 RankMap[BBI] = Rank++;
779 // PropagateBranchInfo - When this method is invoked, we need to propagate
780 // information derived from the branch condition into the true and false
781 // branches of BI. Since we know that there aren't any critical edges in the
782 // flow graph, this can proceed unconditionally.
784 void CEE::PropagateBranchInfo(BranchInst *BI) {
785 assert(BI->isConditional() && "Must be a conditional branch!");
787 // Propagate information into the true block...
789 PropagateEquality(BI->getCondition(), ConstantInt::getTrue(),
790 getRegionInfo(BI->getSuccessor(0)));
792 // Propagate information into the false block...
794 PropagateEquality(BI->getCondition(), ConstantInt::getFalse(),
795 getRegionInfo(BI->getSuccessor(1)));
799 // PropagateSwitchInfo - We need to propagate the value tested by the
800 // switch statement through each case block.
802 void CEE::PropagateSwitchInfo(SwitchInst *SI) {
803 // Propagate information down each of our non-default case labels. We
804 // don't yet propagate information down the default label, because a
805 // potentially large number of inequality constraints provide less
806 // benefit per unit work than a single equality constraint.
808 Value *cond = SI->getCondition();
809 for (unsigned i = 1; i < SI->getNumSuccessors(); ++i)
810 PropagateEquality(cond, SI->getSuccessorValue(i),
811 getRegionInfo(SI->getSuccessor(i)));
815 // PropagateEquality - If we discover that two values are equal to each other in
816 // a specified region, propagate this knowledge recursively.
818 void CEE::PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI) {
819 if (Op0 == Op1) return; // Gee whiz. Are these really equal each other?
821 if (isa<Constant>(Op0)) // Make sure the constant is always Op1
824 // Make sure we don't already know these are equal, to avoid infinite loops...
825 ValueInfo &VI = RI.getValueInfo(Op0);
827 // Get information about the known relationship between Op0 & Op1
828 Relation &KnownRelation = VI.getRelation(Op1);
830 // If we already know they're equal, don't reprocess...
831 if (KnownRelation.getRelation() == FCmpInst::FCMP_OEQ ||
832 KnownRelation.getRelation() == ICmpInst::ICMP_EQ)
835 // If this is boolean, check to see if one of the operands is a constant. If
836 // it's a constant, then see if the other one is one of a setcc instruction,
837 // an AND, OR, or XOR instruction.
839 ConstantInt *CB = dyn_cast<ConstantInt>(Op1);
840 if (CB && Op1->getType() == Type::Int1Ty) {
841 if (Instruction *Inst = dyn_cast<Instruction>(Op0)) {
842 // If we know that this instruction is an AND instruction, and the
843 // result is true, this means that both operands to the OR are known
844 // to be true as well.
846 if (CB->getZExtValue() && Inst->getOpcode() == Instruction::And) {
847 PropagateEquality(Inst->getOperand(0), CB, RI);
848 PropagateEquality(Inst->getOperand(1), CB, RI);
851 // If we know that this instruction is an OR instruction, and the result
852 // is false, this means that both operands to the OR are know to be
855 if (!CB->getZExtValue() && Inst->getOpcode() == Instruction::Or) {
856 PropagateEquality(Inst->getOperand(0), CB, RI);
857 PropagateEquality(Inst->getOperand(1), CB, RI);
860 // If we know that this instruction is a NOT instruction, we know that
861 // the operand is known to be the inverse of whatever the current
864 if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(Inst))
865 if (BinaryOperator::isNot(BOp))
866 PropagateEquality(BinaryOperator::getNotArgument(BOp),
867 ConstantInt::get(Type::Int1Ty,
868 !CB->getZExtValue()), RI);
870 // If we know the value of a FCmp instruction, propagate the information
871 // about the relation into this region as well.
873 if (FCmpInst *FCI = dyn_cast<FCmpInst>(Inst)) {
874 if (CB->getZExtValue()) { // If we know the condition is true...
875 // Propagate info about the LHS to the RHS & RHS to LHS
876 PropagateRelation(FCI->getPredicate(), FCI->getOperand(0),
877 FCI->getOperand(1), RI);
878 PropagateRelation(FCI->getSwappedPredicate(),
879 FCI->getOperand(1), FCI->getOperand(0), RI);
881 } else { // If we know the condition is false...
882 // We know the opposite of the condition is true...
883 FCmpInst::Predicate C = FCI->getInversePredicate();
885 PropagateRelation(C, FCI->getOperand(0), FCI->getOperand(1), RI);
886 PropagateRelation(FCmpInst::getSwappedPredicate(C),
887 FCI->getOperand(1), FCI->getOperand(0), RI);
891 // If we know the value of a ICmp instruction, propagate the information
892 // about the relation into this region as well.
894 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Inst)) {
895 if (CB->getZExtValue()) { // If we know the condition is true...
896 // Propagate info about the LHS to the RHS & RHS to LHS
897 PropagateRelation(ICI->getPredicate(), ICI->getOperand(0),
898 ICI->getOperand(1), RI);
899 PropagateRelation(ICI->getSwappedPredicate(), ICI->getOperand(1),
900 ICI->getOperand(1), RI);
902 } else { // If we know the condition is false ...
903 // We know the opposite of the condition is true...
904 ICmpInst::Predicate C = ICI->getInversePredicate();
906 PropagateRelation(C, ICI->getOperand(0), ICI->getOperand(1), RI);
907 PropagateRelation(ICmpInst::getSwappedPredicate(C),
908 ICI->getOperand(1), ICI->getOperand(0), RI);
914 // Propagate information about Op0 to Op1 & visa versa
915 PropagateRelation(ICmpInst::ICMP_EQ, Op0, Op1, RI);
916 PropagateRelation(ICmpInst::ICMP_EQ, Op1, Op0, RI);
917 PropagateRelation(FCmpInst::FCMP_OEQ, Op0, Op1, RI);
918 PropagateRelation(FCmpInst::FCMP_OEQ, Op1, Op0, RI);
922 // PropagateRelation - We know that the specified relation is true in all of the
923 // blocks in the specified region. Propagate the information about Op0 and
924 // anything derived from it into this region.
926 void CEE::PropagateRelation(unsigned Opcode, Value *Op0,
927 Value *Op1, RegionInfo &RI) {
928 assert(Op0->getType() == Op1->getType() && "Equal types expected!");
930 // Constants are already pretty well understood. We will apply information
931 // about the constant to Op1 in another call to PropagateRelation.
933 if (isa<Constant>(Op0)) return;
935 // Get the region information for this block to update...
936 ValueInfo &VI = RI.getValueInfo(Op0);
938 // Get information about the known relationship between Op0 & Op1
939 Relation &Op1R = VI.getRelation(Op1);
941 // Quick bailout for common case if we are reprocessing an instruction...
942 if (Op1R.getRelation() == Opcode)
945 // If we already have information that contradicts the current information we
946 // are propagating, ignore this info. Something bad must have happened!
948 if (Op1R.contradicts(Opcode, VI)) {
949 Op1R.contradicts(Opcode, VI);
950 cerr << "Contradiction found for opcode: "
951 << ((isa<ICmpInst>(Op0)||isa<ICmpInst>(Op1)) ?
952 Instruction::getOpcodeName(Instruction::ICmp) :
953 Instruction::getOpcodeName(Opcode))
955 Op1R.print(*cerr.stream());
959 // If the information propagated is new, then we want process the uses of this
960 // instruction to propagate the information down to them.
962 if (Op1R.incorporate(Opcode, VI))
963 UpdateUsersOfValue(Op0, RI);
967 // UpdateUsersOfValue - The information about V in this region has been updated.
968 // Propagate this to all consumers of the value.
970 void CEE::UpdateUsersOfValue(Value *V, RegionInfo &RI) {
971 for (Value::use_iterator I = V->use_begin(), E = V->use_end();
973 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
974 // If this is an instruction using a value that we know something about,
975 // try to propagate information to the value produced by the
976 // instruction. We can only do this if it is an instruction we can
977 // propagate information for (a setcc for example), and we only WANT to
978 // do this if the instruction dominates this region.
980 // If the instruction doesn't dominate this region, then it cannot be
981 // used in this region and we don't care about it. If the instruction
982 // is IN this region, then we will simplify the instruction before we
983 // get to uses of it anyway, so there is no reason to bother with it
984 // here. This check is also effectively checking to make sure that Inst
985 // is in the same function as our region (in case V is a global f.e.).
987 if (EF->properlyDominates(Inst->getParent(), RI.getEntryBlock()))
988 IncorporateInstruction(Inst, RI);
992 // IncorporateInstruction - We just updated the information about one of the
993 // operands to the specified instruction. Update the information about the
994 // value produced by this instruction
996 void CEE::IncorporateInstruction(Instruction *Inst, RegionInfo &RI) {
997 if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) {
998 // See if we can figure out a result for this instruction...
999 Relation::KnownResult Result = getCmpResult(CI, RI);
1000 if (Result != Relation::Unknown) {
1001 PropagateEquality(CI, ConstantInt::get(Type::Int1Ty, Result != 0), RI);
1007 // ComputeReplacements - Some values are known to be equal to other values in a
1008 // region. For example if there is a comparison of equality between a variable
1009 // X and a constant C, we can replace all uses of X with C in the region we are
1010 // interested in. We generalize this replacement to replace variables with
1011 // other variables if they are equal and there is a variable with lower rank
1012 // than the current one. This offers a canonicalizing property that exposes
1013 // more redundancies for later transformations to take advantage of.
1015 void CEE::ComputeReplacements(RegionInfo &RI) {
1016 // Loop over all of the values in the region info map...
1017 for (RegionInfo::iterator I = RI.begin(), E = RI.end(); I != E; ++I) {
1018 ValueInfo &VI = I->second;
1020 // If we know that this value is a particular constant, set Replacement to
1022 Value *Replacement = 0;
1023 const APInt * Rplcmnt = VI.getBounds().getSingleElement();
1025 Replacement = ConstantInt::get(*Rplcmnt);
1027 // If this value is not known to be some constant, figure out the lowest
1028 // rank value that it is known to be equal to (if anything).
1030 if (Replacement == 0) {
1031 // Find out if there are any equality relationships with values of lower
1032 // rank than VI itself...
1033 unsigned MinRank = getRank(I->first);
1035 // Loop over the relationships known about Op0.
1036 const std::vector<Relation> &Relationships = VI.getRelationships();
1037 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
1038 if (Relationships[i].getRelation() == FCmpInst::FCMP_OEQ) {
1039 unsigned R = getRank(Relationships[i].getValue());
1042 Replacement = Relationships[i].getValue();
1045 else if (Relationships[i].getRelation() == ICmpInst::ICMP_EQ) {
1046 unsigned R = getRank(Relationships[i].getValue());
1049 Replacement = Relationships[i].getValue();
1054 // If we found something to replace this value with, keep track of it.
1056 VI.setReplacement(Replacement);
1060 // SimplifyBasicBlock - Given information about values in region RI, simplify
1061 // the instructions in the specified basic block.
1063 bool CEE::SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI) {
1064 bool Changed = false;
1065 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ) {
1066 Instruction *Inst = I++;
1068 // Convert instruction arguments to canonical forms...
1069 Changed |= SimplifyInstruction(Inst, RI);
1071 if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) {
1072 // Try to simplify a setcc instruction based on inherited information
1073 Relation::KnownResult Result = getCmpResult(CI, RI);
1074 if (Result != Relation::Unknown) {
1075 DEBUG(cerr << "Replacing icmp with " << Result
1076 << " constant: " << *CI);
1078 CI->replaceAllUsesWith(ConstantInt::get(Type::Int1Ty, (bool)Result));
1079 // The instruction is now dead, remove it from the program.
1080 CI->getParent()->getInstList().erase(CI);
1090 // SimplifyInstruction - Inspect the operands of the instruction, converting
1091 // them to their canonical form if possible. This takes care of, for example,
1092 // replacing a value 'X' with a constant 'C' if the instruction in question is
1093 // dominated by a true seteq 'X', 'C'.
1095 bool CEE::SimplifyInstruction(Instruction *I, const RegionInfo &RI) {
1096 bool Changed = false;
1098 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1099 if (const ValueInfo *VI = RI.requestValueInfo(I->getOperand(i)))
1100 if (Value *Repl = VI->getReplacement()) {
1101 // If we know if a replacement with lower rank than Op0, make the
1103 DOUT << "In Inst: " << *I << " Replacing operand #" << i
1104 << " with " << *Repl << "\n";
1105 I->setOperand(i, Repl);
1113 // getCmpResult - Try to simplify a cmp instruction based on information
1114 // inherited from a dominating icmp instruction. V is one of the operands to
1115 // the icmp instruction, and VI is the set of information known about it. We
1116 // take two cases into consideration here. If the comparison is against a
1117 // constant value, we can use the constant range to see if the comparison is
1118 // possible to succeed. If it is not a comparison against a constant, we check
1119 // to see if there is a known relationship between the two values. If so, we
1120 // may be able to eliminate the check.
1122 Relation::KnownResult CEE::getCmpResult(CmpInst *CI,
1123 const RegionInfo &RI) {
1124 Value *Op0 = CI->getOperand(0), *Op1 = CI->getOperand(1);
1125 unsigned short predicate = CI->getPredicate();
1127 if (isa<Constant>(Op0)) {
1128 if (isa<Constant>(Op1)) {
1129 if (Constant *Result = ConstantFoldInstruction(CI)) {
1130 // Wow, this is easy, directly eliminate the ICmpInst.
1131 DEBUG(cerr << "Replacing cmp with constant fold: " << *CI);
1132 return cast<ConstantInt>(Result)->getZExtValue()
1133 ? Relation::KnownTrue : Relation::KnownFalse;
1136 // We want to swap this instruction so that operand #0 is the constant.
1137 std::swap(Op0, Op1);
1138 if (isa<ICmpInst>(CI))
1139 predicate = cast<ICmpInst>(CI)->getSwappedPredicate();
1141 predicate = cast<FCmpInst>(CI)->getSwappedPredicate();
1145 // Try to figure out what the result of this comparison will be...
1146 Relation::KnownResult Result = Relation::Unknown;
1148 // We have to know something about the relationship to prove anything...
1149 if (const ValueInfo *Op0VI = RI.requestValueInfo(Op0)) {
1151 // At this point, we know that if we have a constant argument that it is in
1152 // Op1. Check to see if we know anything about comparing value with a
1153 // constant, and if we can use this info to fold the icmp.
1155 if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
1156 // Check to see if we already know the result of this comparison...
1157 ICmpInst::Predicate ipred = ICmpInst::Predicate(predicate);
1158 ConstantRange R = ICmpInst::makeConstantRange(ipred, C->getValue());
1159 ConstantRange Int = R.intersectWith(Op0VI->getBounds());
1161 // If the intersection of the two ranges is empty, then the condition
1162 // could never be true!
1164 if (Int.isEmptySet()) {
1165 Result = Relation::KnownFalse;
1167 // Otherwise, if VI.getBounds() (the possible values) is a subset of R
1168 // (the allowed values) then we know that the condition must always be
1171 } else if (Int == Op0VI->getBounds()) {
1172 Result = Relation::KnownTrue;
1175 // If we are here, we know that the second argument is not a constant
1176 // integral. See if we know anything about Op0 & Op1 that allows us to
1177 // fold this anyway.
1179 // Do we have value information about Op0 and a relation to Op1?
1180 if (const Relation *Op2R = Op0VI->requestRelation(Op1))
1181 Result = Op2R->getImpliedResult(predicate);
1187 //===----------------------------------------------------------------------===//
1188 // Relation Implementation
1189 //===----------------------------------------------------------------------===//
1191 // contradicts - Return true if the relationship specified by the operand
1192 // contradicts already known information.
1194 bool Relation::contradicts(unsigned Op,
1195 const ValueInfo &VI) const {
1196 assert (Op != Instruction::Add && "Invalid relation argument!");
1198 // If this is a relationship with a constant, make sure that this relationship
1199 // does not contradict properties known about the bounds of the constant.
1201 if (ConstantInt *C = dyn_cast<ConstantInt>(Val))
1202 if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
1203 Op <= ICmpInst::LAST_ICMP_PREDICATE) {
1204 ICmpInst::Predicate ipred = ICmpInst::Predicate(Op);
1205 if (ICmpInst::makeConstantRange(ipred, C->getValue())
1206 .intersectWith(VI.getBounds()).isEmptySet())
1211 default: assert(0 && "Unknown Relationship code!");
1212 case Instruction::Add: return false; // Nothing known, nothing contradicts
1213 case ICmpInst::ICMP_EQ:
1214 return Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_SLT ||
1215 Op == ICmpInst::ICMP_UGT || Op == ICmpInst::ICMP_SGT ||
1216 Op == ICmpInst::ICMP_NE;
1217 case ICmpInst::ICMP_NE: return Op == ICmpInst::ICMP_EQ;
1218 case ICmpInst::ICMP_ULE:
1219 case ICmpInst::ICMP_SLE: return Op == ICmpInst::ICMP_UGT ||
1220 Op == ICmpInst::ICMP_SGT;
1221 case ICmpInst::ICMP_UGE:
1222 case ICmpInst::ICMP_SGE: return Op == ICmpInst::ICMP_ULT ||
1223 Op == ICmpInst::ICMP_SLT;
1224 case ICmpInst::ICMP_ULT:
1225 case ICmpInst::ICMP_SLT:
1226 return Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_UGT ||
1227 Op == ICmpInst::ICMP_SGT || Op == ICmpInst::ICMP_UGE ||
1228 Op == ICmpInst::ICMP_SGE;
1229 case ICmpInst::ICMP_UGT:
1230 case ICmpInst::ICMP_SGT:
1231 return Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_ULT ||
1232 Op == ICmpInst::ICMP_SLT || Op == ICmpInst::ICMP_ULE ||
1233 Op == ICmpInst::ICMP_SLE;
1234 case FCmpInst::FCMP_OEQ:
1235 return Op == FCmpInst::FCMP_OLT || Op == FCmpInst::FCMP_OGT ||
1236 Op == FCmpInst::FCMP_ONE;
1237 case FCmpInst::FCMP_ONE: return Op == FCmpInst::FCMP_OEQ;
1238 case FCmpInst::FCMP_OLE: return Op == FCmpInst::FCMP_OGT;
1239 case FCmpInst::FCMP_OGE: return Op == FCmpInst::FCMP_OLT;
1240 case FCmpInst::FCMP_OLT:
1241 return Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OGT ||
1242 Op == FCmpInst::FCMP_OGE;
1243 case FCmpInst::FCMP_OGT:
1244 return Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OLT ||
1245 Op == FCmpInst::FCMP_OLE;
1249 // incorporate - Incorporate information in the argument into this relation
1250 // entry. This assumes that the information doesn't contradict itself. If any
1251 // new information is gained, true is returned, otherwise false is returned to
1252 // indicate that nothing was updated.
1254 bool Relation::incorporate(unsigned Op, ValueInfo &VI) {
1255 assert(!contradicts(Op, VI) &&
1256 "Cannot incorporate contradictory information!");
1258 // If this is a relationship with a constant, make sure that we update the
1259 // range that is possible for the value to have...
1261 if (ConstantInt *C = dyn_cast<ConstantInt>(Val))
1262 if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
1263 Op <= ICmpInst::LAST_ICMP_PREDICATE) {
1264 ICmpInst::Predicate ipred = ICmpInst::Predicate(Op);
1266 ICmpInst::makeConstantRange(ipred, C->getValue())
1267 .intersectWith(VI.getBounds());
1271 default: assert(0 && "Unknown prior value!");
1272 case Instruction::Add: Rel = Op; return true;
1273 case ICmpInst::ICMP_EQ:
1274 case ICmpInst::ICMP_NE:
1275 case ICmpInst::ICMP_ULT:
1276 case ICmpInst::ICMP_SLT:
1277 case ICmpInst::ICMP_UGT:
1278 case ICmpInst::ICMP_SGT: return false; // Nothing is more precise
1279 case ICmpInst::ICMP_ULE:
1280 case ICmpInst::ICMP_SLE:
1281 if (Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_ULT ||
1282 Op == ICmpInst::ICMP_SLT) {
1285 } else if (Op == ICmpInst::ICMP_NE) {
1286 Rel = Rel == ICmpInst::ICMP_ULE ? ICmpInst::ICMP_ULT :
1291 case ICmpInst::ICMP_UGE:
1292 case ICmpInst::ICMP_SGE:
1293 if (Op == ICmpInst::ICMP_EQ || ICmpInst::ICMP_UGT ||
1294 Op == ICmpInst::ICMP_SGT) {
1297 } else if (Op == ICmpInst::ICMP_NE) {
1298 Rel = Rel == ICmpInst::ICMP_UGE ? ICmpInst::ICMP_UGT :
1303 case FCmpInst::FCMP_OEQ: return false; // Nothing is more precise
1304 case FCmpInst::FCMP_ONE: return false; // Nothing is more precise
1305 case FCmpInst::FCMP_OLT: return false; // Nothing is more precise
1306 case FCmpInst::FCMP_OGT: return false; // Nothing is more precise
1307 case FCmpInst::FCMP_OLE:
1308 if (Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OLT) {
1311 } else if (Op == FCmpInst::FCMP_ONE) {
1312 Rel = FCmpInst::FCMP_OLT;
1316 case FCmpInst::FCMP_OGE:
1317 return Op == FCmpInst::FCMP_OLT;
1318 if (Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OGT) {
1321 } else if (Op == FCmpInst::FCMP_ONE) {
1322 Rel = FCmpInst::FCMP_OGT;
1329 // getImpliedResult - If this relationship between two values implies that
1330 // the specified relationship is true or false, return that. If we cannot
1331 // determine the result required, return Unknown.
1333 Relation::KnownResult
1334 Relation::getImpliedResult(unsigned Op) const {
1335 if (Rel == Op) return KnownTrue;
1336 if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
1337 Op <= ICmpInst::LAST_ICMP_PREDICATE) {
1338 if (Rel == unsigned(ICmpInst::getInversePredicate(ICmpInst::Predicate(Op))))
1340 } else if (Op <= FCmpInst::LAST_FCMP_PREDICATE) {
1341 if (Rel == unsigned(FCmpInst::getInversePredicate(FCmpInst::Predicate(Op))))
1346 default: assert(0 && "Unknown prior value!");
1347 case ICmpInst::ICMP_EQ:
1348 if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_SLE ||
1349 Op == ICmpInst::ICMP_UGE || Op == ICmpInst::ICMP_SGE) return KnownTrue;
1350 if (Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_SLT ||
1351 Op == ICmpInst::ICMP_UGT || Op == ICmpInst::ICMP_SGT) return KnownFalse;
1353 case ICmpInst::ICMP_ULT:
1354 case ICmpInst::ICMP_SLT:
1355 if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_SLE ||
1356 Op == ICmpInst::ICMP_NE) return KnownTrue;
1357 if (Op == ICmpInst::ICMP_EQ) return KnownFalse;
1359 case ICmpInst::ICMP_UGT:
1360 case ICmpInst::ICMP_SGT:
1361 if (Op == ICmpInst::ICMP_UGE || Op == ICmpInst::ICMP_SGE ||
1362 Op == ICmpInst::ICMP_NE) return KnownTrue;
1363 if (Op == ICmpInst::ICMP_EQ) return KnownFalse;
1365 case FCmpInst::FCMP_OEQ:
1366 if (Op == FCmpInst::FCMP_OLE || Op == FCmpInst::FCMP_OGE) return KnownTrue;
1367 if (Op == FCmpInst::FCMP_OLT || Op == FCmpInst::FCMP_OGT) return KnownFalse;
1369 case FCmpInst::FCMP_OLT:
1370 if (Op == FCmpInst::FCMP_ONE || Op == FCmpInst::FCMP_OLE) return KnownTrue;
1371 if (Op == FCmpInst::FCMP_OEQ) return KnownFalse;
1373 case FCmpInst::FCMP_OGT:
1374 if (Op == FCmpInst::FCMP_ONE || Op == FCmpInst::FCMP_OGE) return KnownTrue;
1375 if (Op == FCmpInst::FCMP_OEQ) return KnownFalse;
1377 case ICmpInst::ICMP_NE:
1378 case ICmpInst::ICMP_SLE:
1379 case ICmpInst::ICMP_ULE:
1380 case ICmpInst::ICMP_UGE:
1381 case ICmpInst::ICMP_SGE:
1382 case FCmpInst::FCMP_ONE:
1383 case FCmpInst::FCMP_OLE:
1384 case FCmpInst::FCMP_OGE:
1385 case FCmpInst::FCMP_FALSE:
1386 case FCmpInst::FCMP_ORD:
1387 case FCmpInst::FCMP_UNO:
1388 case FCmpInst::FCMP_UEQ:
1389 case FCmpInst::FCMP_UGT:
1390 case FCmpInst::FCMP_UGE:
1391 case FCmpInst::FCMP_ULT:
1392 case FCmpInst::FCMP_ULE:
1393 case FCmpInst::FCMP_UNE:
1394 case FCmpInst::FCMP_TRUE:
1401 //===----------------------------------------------------------------------===//
1402 // Printing Support...
1403 //===----------------------------------------------------------------------===//
1405 // print - Implement the standard print form to print out analysis information.
1406 void CEE::print(std::ostream &O, const Module *M) const {
1407 O << "\nPrinting Correlated Expression Info:\n";
1408 for (std::map<BasicBlock*, RegionInfo>::const_iterator I =
1409 RegionInfoMap.begin(), E = RegionInfoMap.end(); I != E; ++I)
1413 // print - Output information about this region...
1414 void RegionInfo::print(std::ostream &OS) const {
1415 if (ValueMap.empty()) return;
1417 OS << " RegionInfo for basic block: " << BB->getName() << "\n";
1418 for (std::map<Value*, ValueInfo>::const_iterator
1419 I = ValueMap.begin(), E = ValueMap.end(); I != E; ++I)
1420 I->second.print(OS, I->first);
1424 // print - Output information about this value relation...
1425 void ValueInfo::print(std::ostream &OS, Value *V) const {
1426 if (Relationships.empty()) return;
1429 OS << " ValueInfo for: ";
1430 WriteAsOperand(OS, V);
1432 OS << "\n Bounds = " << Bounds << "\n";
1434 OS << " Replacement = ";
1435 WriteAsOperand(OS, Replacement);
1438 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
1439 Relationships[i].print(OS);
1442 // print - Output this relation to the specified stream
1443 void Relation::print(std::ostream &OS) const {
1446 default: OS << "*UNKNOWN*"; break;
1447 case ICmpInst::ICMP_EQ:
1448 case FCmpInst::FCMP_ORD:
1449 case FCmpInst::FCMP_UEQ:
1450 case FCmpInst::FCMP_OEQ: OS << "== "; break;
1451 case ICmpInst::ICMP_NE:
1452 case FCmpInst::FCMP_UNO:
1453 case FCmpInst::FCMP_UNE:
1454 case FCmpInst::FCMP_ONE: OS << "!= "; break;
1455 case ICmpInst::ICMP_ULT:
1456 case ICmpInst::ICMP_SLT:
1457 case FCmpInst::FCMP_ULT:
1458 case FCmpInst::FCMP_OLT: OS << "< "; break;
1459 case ICmpInst::ICMP_UGT:
1460 case ICmpInst::ICMP_SGT:
1461 case FCmpInst::FCMP_UGT:
1462 case FCmpInst::FCMP_OGT: OS << "> "; break;
1463 case ICmpInst::ICMP_ULE:
1464 case ICmpInst::ICMP_SLE:
1465 case FCmpInst::FCMP_ULE:
1466 case FCmpInst::FCMP_OLE: OS << "<= "; break;
1467 case ICmpInst::ICMP_UGE:
1468 case ICmpInst::ICMP_SGE:
1469 case FCmpInst::FCMP_UGE:
1470 case FCmpInst::FCMP_OGE: OS << ">= "; break;
1473 WriteAsOperand(OS, Val);
1477 // Don't inline these methods or else we won't be able to call them from GDB!
1478 void Relation::dump() const { print(*cerr.stream()); }
1479 void ValueInfo::dump() const { print(*cerr.stream(), 0); }
1480 void RegionInfo::dump() const { print(*cerr.stream()); }