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;
228 static char ID; // Pass identification, replacement for typeid
229 CEE() : FunctionPass((intptr_t)&ID) {}
231 virtual bool runOnFunction(Function &F);
233 // We don't modify the program, so we preserve all analyses
234 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
235 AU.addRequired<DominatorTree>();
236 AU.addRequiredID(BreakCriticalEdgesID);
239 // print - Implement the standard print form to print out analysis
241 virtual void print(std::ostream &O, const Module *M) const;
244 RegionInfo &getRegionInfo(BasicBlock *BB) {
245 std::map<BasicBlock*, RegionInfo>::iterator I
246 = RegionInfoMap.lower_bound(BB);
247 if (I != RegionInfoMap.end() && I->first == BB) return I->second;
248 return RegionInfoMap.insert(I, std::make_pair(BB, BB))->second;
251 void BuildRankMap(Function &F);
252 unsigned getRank(Value *V) const {
253 if (isa<Constant>(V)) return 0;
254 std::map<Value*, unsigned>::const_iterator I = RankMap.find(V);
255 if (I != RankMap.end()) return I->second;
256 return 0; // Must be some other global thing
259 bool TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks);
261 bool ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
264 void ForwardSuccessorTo(TerminatorInst *TI, unsigned Succ, BasicBlock *D,
266 void ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
267 BasicBlock *RegionDominator);
268 void CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
269 std::vector<BasicBlock*> &RegionExitBlocks);
270 void InsertRegionExitMerges(PHINode *NewPHI, Instruction *OldVal,
271 const std::vector<BasicBlock*> &RegionExitBlocks);
273 void PropagateBranchInfo(BranchInst *BI);
274 void PropagateSwitchInfo(SwitchInst *SI);
275 void PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI);
276 void PropagateRelation(unsigned Opcode, Value *Op0,
277 Value *Op1, RegionInfo &RI);
278 void UpdateUsersOfValue(Value *V, RegionInfo &RI);
279 void IncorporateInstruction(Instruction *Inst, RegionInfo &RI);
280 void ComputeReplacements(RegionInfo &RI);
282 // getCmpResult - Given a icmp instruction, determine if the result is
283 // determined by facts we already know about the region under analysis.
284 // Return KnownTrue, KnownFalse, or UnKnown based on what we can determine.
285 Relation::KnownResult getCmpResult(CmpInst *ICI, const RegionInfo &RI);
287 bool SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI);
288 bool SimplifyInstruction(Instruction *Inst, const RegionInfo &RI);
292 RegisterPass<CEE> X("cee", "Correlated Expression Elimination");
295 FunctionPass *llvm::createCorrelatedExpressionEliminationPass() {
300 bool CEE::runOnFunction(Function &F) {
301 // Build a rank map for the function...
304 // Traverse the dominator tree, computing information for each node in the
305 // tree. Note that our traversal will not even touch unreachable basic
307 DT = &getAnalysis<DominatorTree>();
309 std::set<BasicBlock*> VisitedBlocks;
310 bool Changed = TransformRegion(&F.getEntryBlock(), VisitedBlocks);
312 RegionInfoMap.clear();
317 // TransformRegion - Transform the region starting with BB according to the
318 // calculated region information for the block. Transforming the region
319 // involves analyzing any information this block provides to successors,
320 // propagating the information to successors, and finally transforming
323 // This method processes the function in depth first order, which guarantees
324 // that we process the immediate dominator of a block before the block itself.
325 // Because we are passing information from immediate dominators down to
326 // dominatees, we obviously have to process the information source before the
327 // information consumer.
329 bool CEE::TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks){
330 // Prevent infinite recursion...
331 if (VisitedBlocks.count(BB)) return false;
332 VisitedBlocks.insert(BB);
334 // Get the computed region information for this block...
335 RegionInfo &RI = getRegionInfo(BB);
337 // Compute the replacement information for this block...
338 ComputeReplacements(RI);
340 // If debugging, print computed region information...
341 DEBUG(RI.print(*cerr.stream()));
343 // Simplify the contents of this block...
344 bool Changed = SimplifyBasicBlock(*BB, RI);
346 // Get the terminator of this basic block...
347 TerminatorInst *TI = BB->getTerminator();
349 // Loop over all of the blocks that this block is the immediate dominator for.
350 // Because all information known in this region is also known in all of the
351 // blocks that are dominated by this one, we can safely propagate the
352 // information down now.
354 DomTreeNode *BBDom = DT->getNode(BB);
355 if (!RI.empty()) { // Time opt: only propagate if we can change something
356 for (std::vector<DomTreeNode*>::iterator DI = BBDom->begin(),
357 E = BBDom->end(); DI != E; ++DI) {
358 BasicBlock *ChildBB = (*DI)->getBlock();
359 assert(RegionInfoMap.find(ChildBB) == RegionInfoMap.end() &&
360 "RegionInfo should be calculated in dominanace order!");
361 getRegionInfo(ChildBB) = RI;
365 // Now that all of our successors have information if they deserve it,
366 // propagate any information our terminator instruction finds to our
368 if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
369 if (BI->isConditional())
370 PropagateBranchInfo(BI);
371 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
372 PropagateSwitchInfo(SI);
375 // If this is a branch to a block outside our region that simply performs
376 // another conditional branch, one whose outcome is known inside of this
377 // region, then vector this outgoing edge directly to the known destination.
379 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
380 while (ForwardCorrelatedEdgeDestination(TI, i, RI)) {
385 // Now that all of our successors have information, recursively process them.
386 for (std::vector<DomTreeNode*>::iterator DI = BBDom->begin(),
387 E = BBDom->end(); DI != E; ++DI) {
388 BasicBlock *ChildBB = (*DI)->getBlock();
389 Changed |= TransformRegion(ChildBB, VisitedBlocks);
395 // isBlockSimpleEnoughForCheck to see if the block is simple enough for us to
396 // revector the conditional branch in the bottom of the block, do so now.
398 static bool isBlockSimpleEnough(BasicBlock *BB) {
399 assert(isa<BranchInst>(BB->getTerminator()));
400 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
401 assert(BI->isConditional());
403 // Check the common case first: empty block, or block with just a setcc.
404 if (BB->size() == 1 ||
405 (BB->size() == 2 && &BB->front() == BI->getCondition() &&
406 BI->getCondition()->hasOneUse()))
409 // Check the more complex case now...
410 BasicBlock::iterator I = BB->begin();
412 // FIXME: This should be reenabled once the regression with SIM is fixed!
414 // PHI Nodes are ok, just skip over them...
415 while (isa<PHINode>(*I)) ++I;
418 // Accept the setcc instruction...
419 if (&*I == BI->getCondition())
422 // Nothing else is acceptable here yet. We must not revector... unless we are
423 // at the terminator instruction.
431 bool CEE::ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
433 // If this successor is a simple block not in the current region, which
434 // contains only a conditional branch, we decide if the outcome of the branch
435 // can be determined from information inside of the region. Instead of going
436 // to this block, we can instead go to the destination we know is the right
440 // Check to see if we dominate the block. If so, this block will get the
441 // condition turned to a constant anyway.
443 //if (EF->dominates(RI.getEntryBlock(), BB))
446 BasicBlock *BB = TI->getParent();
448 // Get the destination block of this edge...
449 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
451 // Make sure that the block ends with a conditional branch and is simple
452 // enough for use to be able to revector over.
453 BranchInst *BI = dyn_cast<BranchInst>(OldSucc->getTerminator());
454 if (BI == 0 || !BI->isConditional() || !isBlockSimpleEnough(OldSucc))
457 // We can only forward the branch over the block if the block ends with a
458 // cmp we can determine the outcome for.
460 // FIXME: we can make this more generic. Code below already handles more
462 if (!isa<CmpInst>(BI->getCondition()))
465 // Make a new RegionInfo structure so that we can simulate the effect of the
466 // PHI nodes in the block we are skipping over...
468 RegionInfo NewRI(RI);
470 // Remove value information for all of the values we are simulating... to make
471 // sure we don't have any stale information.
472 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
473 if (I->getType() != Type::VoidTy)
474 NewRI.removeValueInfo(I);
476 // Put the newly discovered information into the RegionInfo...
477 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
478 if (PHINode *PN = dyn_cast<PHINode>(I)) {
479 int OpNum = PN->getBasicBlockIndex(BB);
480 assert(OpNum != -1 && "PHI doesn't have incoming edge for predecessor!?");
481 PropagateEquality(PN, PN->getIncomingValue(OpNum), NewRI);
482 } else if (CmpInst *CI = dyn_cast<CmpInst>(I)) {
483 Relation::KnownResult Res = getCmpResult(CI, NewRI);
484 if (Res == Relation::Unknown) return false;
485 PropagateEquality(CI, ConstantInt::get(Type::Int1Ty, Res), NewRI);
487 assert(isa<BranchInst>(*I) && "Unexpected instruction type!");
490 // Compute the facts implied by what we have discovered...
491 ComputeReplacements(NewRI);
493 ValueInfo &PredicateVI = NewRI.getValueInfo(BI->getCondition());
494 if (PredicateVI.getReplacement() &&
495 isa<Constant>(PredicateVI.getReplacement()) &&
496 !isa<GlobalValue>(PredicateVI.getReplacement())) {
497 ConstantInt *CB = cast<ConstantInt>(PredicateVI.getReplacement());
499 // Forward to the successor that corresponds to the branch we will take.
500 ForwardSuccessorTo(TI, SuccNo,
501 BI->getSuccessor(!CB->getZExtValue()), NewRI);
508 static Value *getReplacementOrValue(Value *V, RegionInfo &RI) {
509 if (const ValueInfo *VI = RI.requestValueInfo(V))
510 if (Value *Repl = VI->getReplacement())
515 /// ForwardSuccessorTo - We have found that we can forward successor # 'SuccNo'
516 /// of Terminator 'TI' to the 'Dest' BasicBlock. This method performs the
517 /// mechanics of updating SSA information and revectoring the branch.
519 void CEE::ForwardSuccessorTo(TerminatorInst *TI, unsigned SuccNo,
520 BasicBlock *Dest, RegionInfo &RI) {
521 // If there are any PHI nodes in the Dest BB, we must duplicate the entry
522 // in the PHI node for the old successor to now include an entry from the
523 // current basic block.
525 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
526 BasicBlock *BB = TI->getParent();
528 DOUT << "Forwarding branch in basic block %" << BB->getName()
529 << " from block %" << OldSucc->getName() << " to block %"
530 << Dest->getName() << "\n"
531 << "Before forwarding: " << *BB->getParent();
533 // Because we know that there cannot be critical edges in the flow graph, and
534 // that OldSucc has multiple outgoing edges, this means that Dest cannot have
535 // multiple incoming edges.
538 pred_iterator DPI = pred_begin(Dest); ++DPI;
539 assert(DPI == pred_end(Dest) && "Critical edge found!!");
542 // Loop over any PHI nodes in the destination, eliminating them, because they
543 // may only have one input.
545 while (PHINode *PN = dyn_cast<PHINode>(&Dest->front())) {
546 assert(PN->getNumIncomingValues() == 1 && "Crit edge found!");
547 // Eliminate the PHI node
548 PN->replaceAllUsesWith(PN->getIncomingValue(0));
549 Dest->getInstList().erase(PN);
552 // If there are values defined in the "OldSucc" basic block, we need to insert
553 // PHI nodes in the regions we are dealing with to emulate them. This can
554 // insert dead phi nodes, but it is more trouble to see if they are used than
555 // to just blindly insert them.
557 if (DT->dominates(OldSucc, Dest)) {
558 // RegionExitBlocks - Find all of the blocks that are not dominated by Dest,
559 // but have predecessors that are. Additionally, prune down the set to only
560 // include blocks that are dominated by OldSucc as well.
562 std::vector<BasicBlock*> RegionExitBlocks;
563 CalculateRegionExitBlocks(Dest, OldSucc, RegionExitBlocks);
565 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end();
567 if (I->getType() != Type::VoidTy) {
568 // Create and insert the PHI node into the top of Dest.
569 PHINode *NewPN = new PHINode(I->getType(), I->getName()+".fw_merge",
571 // There is definitely an edge from OldSucc... add the edge now
572 NewPN->addIncoming(I, OldSucc);
574 // There is also an edge from BB now, add the edge with the calculated
575 // value from the RI.
576 NewPN->addIncoming(getReplacementOrValue(I, RI), BB);
578 // Make everything in the Dest region use the new PHI node now...
579 ReplaceUsesOfValueInRegion(I, NewPN, Dest);
581 // Make sure that exits out of the region dominated by NewPN get PHI
582 // nodes that merge the values as appropriate.
583 InsertRegionExitMerges(NewPN, I, RegionExitBlocks);
587 // If there were PHI nodes in OldSucc, we need to remove the entry for this
588 // edge from the PHI node, and we need to replace any references to the PHI
589 // node with a new value.
591 for (BasicBlock::iterator I = OldSucc->begin(); isa<PHINode>(I); ) {
592 PHINode *PN = cast<PHINode>(I);
594 // Get the value flowing across the old edge and remove the PHI node entry
595 // for this edge: we are about to remove the edge! Don't remove the PHI
596 // node yet though if this is the last edge into it.
597 Value *EdgeValue = PN->removeIncomingValue(BB, false);
599 // Make sure that anything that used to use PN now refers to EdgeValue
600 ReplaceUsesOfValueInRegion(PN, EdgeValue, Dest);
602 // If there is only one value left coming into the PHI node, replace the PHI
603 // node itself with the one incoming value left.
605 if (PN->getNumIncomingValues() == 1) {
606 assert(PN->getNumIncomingValues() == 1);
607 PN->replaceAllUsesWith(PN->getIncomingValue(0));
608 PN->getParent()->getInstList().erase(PN);
609 I = OldSucc->begin();
610 } else if (PN->getNumIncomingValues() == 0) { // Nuke the PHI
611 // If we removed the last incoming value to this PHI, nuke the PHI node
613 PN->replaceAllUsesWith(Constant::getNullValue(PN->getType()));
614 PN->getParent()->getInstList().erase(PN);
615 I = OldSucc->begin();
617 ++I; // Otherwise, move on to the next PHI node
621 // Actually revector the branch now...
622 TI->setSuccessor(SuccNo, Dest);
624 // If we just introduced a critical edge in the flow graph, make sure to break
626 SplitCriticalEdge(TI, SuccNo, this);
628 // Make sure that we don't introduce critical edges from oldsucc now!
629 for (unsigned i = 0, e = OldSucc->getTerminator()->getNumSuccessors();
631 SplitCriticalEdge(OldSucc->getTerminator(), i, this);
633 // Since we invalidated the CFG, recalculate the dominator set so that it is
634 // useful for later processing!
635 // FIXME: This is much worse than it really should be!
638 DOUT << "After forwarding: " << *BB->getParent();
641 /// ReplaceUsesOfValueInRegion - This method replaces all uses of Orig with uses
642 /// of New. It only affects instructions that are defined in basic blocks that
643 /// are dominated by Head.
645 void CEE::ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
646 BasicBlock *RegionDominator) {
647 assert(Orig != New && "Cannot replace value with itself");
648 std::vector<Instruction*> InstsToChange;
649 std::vector<PHINode*> PHIsToChange;
650 InstsToChange.reserve(Orig->getNumUses());
652 // Loop over instructions adding them to InstsToChange vector, this allows us
653 // an easy way to avoid invalidating the use_iterator at a bad time.
654 for (Value::use_iterator I = Orig->use_begin(), E = Orig->use_end();
656 if (Instruction *User = dyn_cast<Instruction>(*I))
657 if (DT->dominates(RegionDominator, User->getParent()))
658 InstsToChange.push_back(User);
659 else if (PHINode *PN = dyn_cast<PHINode>(User)) {
660 PHIsToChange.push_back(PN);
663 // PHIsToChange contains PHI nodes that use Orig that do not live in blocks
664 // dominated by orig. If the block the value flows in from is dominated by
665 // RegionDominator, then we rewrite the PHI
666 for (unsigned i = 0, e = PHIsToChange.size(); i != e; ++i) {
667 PHINode *PN = PHIsToChange[i];
668 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
669 if (PN->getIncomingValue(j) == Orig &&
670 DT->dominates(RegionDominator, PN->getIncomingBlock(j)))
671 PN->setIncomingValue(j, New);
674 // Loop over the InstsToChange list, replacing all uses of Orig with uses of
675 // New. This list contains all of the instructions in our region that use
677 for (unsigned i = 0, e = InstsToChange.size(); i != e; ++i)
678 if (PHINode *PN = dyn_cast<PHINode>(InstsToChange[i])) {
679 // PHINodes must be handled carefully. If the PHI node itself is in the
680 // region, we have to make sure to only do the replacement for incoming
681 // values that correspond to basic blocks in the region.
682 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
683 if (PN->getIncomingValue(j) == Orig &&
684 DT->dominates(RegionDominator, PN->getIncomingBlock(j)))
685 PN->setIncomingValue(j, New);
688 InstsToChange[i]->replaceUsesOfWith(Orig, New);
692 static void CalcRegionExitBlocks(BasicBlock *Header, BasicBlock *BB,
693 std::set<BasicBlock*> &Visited,
695 std::vector<BasicBlock*> &RegionExitBlocks) {
696 if (Visited.count(BB)) return;
699 if (DT.dominates(Header, BB)) { // Block in the region, recursively traverse
700 for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
701 CalcRegionExitBlocks(Header, *I, Visited, DT, RegionExitBlocks);
703 // Header does not dominate this block, but we have a predecessor that does
704 // dominate us. Add ourself to the list.
705 RegionExitBlocks.push_back(BB);
709 /// CalculateRegionExitBlocks - Find all of the blocks that are not dominated by
710 /// BB, but have predecessors that are. Additionally, prune down the set to
711 /// only include blocks that are dominated by OldSucc as well.
713 void CEE::CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
714 std::vector<BasicBlock*> &RegionExitBlocks){
715 std::set<BasicBlock*> Visited; // Don't infinite loop
717 // Recursively calculate blocks we are interested in...
718 CalcRegionExitBlocks(BB, BB, Visited, *DT, RegionExitBlocks);
720 // Filter out blocks that are not dominated by OldSucc...
721 for (unsigned i = 0; i != RegionExitBlocks.size(); ) {
722 if (DT->dominates(OldSucc, RegionExitBlocks[i]))
723 ++i; // Block is ok, keep it.
725 // Move to end of list...
726 std::swap(RegionExitBlocks[i], RegionExitBlocks.back());
727 RegionExitBlocks.pop_back(); // Nuke the end
732 void CEE::InsertRegionExitMerges(PHINode *BBVal, Instruction *OldVal,
733 const std::vector<BasicBlock*> &RegionExitBlocks) {
734 assert(BBVal->getType() == OldVal->getType() && "Should be derived values!");
735 BasicBlock *BB = BBVal->getParent();
737 // Loop over all of the blocks we have to place PHIs in, doing it.
738 for (unsigned i = 0, e = RegionExitBlocks.size(); i != e; ++i) {
739 BasicBlock *FBlock = RegionExitBlocks[i]; // Block on the frontier
741 // Create the new PHI node
742 PHINode *NewPN = new PHINode(BBVal->getType(),
743 OldVal->getName()+".fw_frontier",
746 // Add an incoming value for every predecessor of the block...
747 for (pred_iterator PI = pred_begin(FBlock), PE = pred_end(FBlock);
749 // If the incoming edge is from the region dominated by BB, use BBVal,
750 // otherwise use OldVal.
751 NewPN->addIncoming(DT->dominates(BB, *PI) ? BBVal : OldVal, *PI);
754 // Now make everyone dominated by this block use this new value!
755 ReplaceUsesOfValueInRegion(OldVal, NewPN, FBlock);
761 // BuildRankMap - This method builds the rank map data structure which gives
762 // each instruction/value in the function a value based on how early it appears
763 // in the function. We give constants and globals rank 0, arguments are
764 // numbered starting at one, and instructions are numbered in reverse post-order
765 // from where the arguments leave off. This gives instructions in loops higher
766 // values than instructions not in loops.
768 void CEE::BuildRankMap(Function &F) {
769 unsigned Rank = 1; // Skip rank zero.
771 // Number the arguments...
772 for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
775 // Number the instructions in reverse post order...
776 ReversePostOrderTraversal<Function*> RPOT(&F);
777 for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
778 E = RPOT.end(); I != E; ++I)
779 for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end();
781 if (BBI->getType() != Type::VoidTy)
782 RankMap[BBI] = Rank++;
786 // PropagateBranchInfo - When this method is invoked, we need to propagate
787 // information derived from the branch condition into the true and false
788 // branches of BI. Since we know that there aren't any critical edges in the
789 // flow graph, this can proceed unconditionally.
791 void CEE::PropagateBranchInfo(BranchInst *BI) {
792 assert(BI->isConditional() && "Must be a conditional branch!");
794 // Propagate information into the true block...
796 PropagateEquality(BI->getCondition(), ConstantInt::getTrue(),
797 getRegionInfo(BI->getSuccessor(0)));
799 // Propagate information into the false block...
801 PropagateEquality(BI->getCondition(), ConstantInt::getFalse(),
802 getRegionInfo(BI->getSuccessor(1)));
806 // PropagateSwitchInfo - We need to propagate the value tested by the
807 // switch statement through each case block.
809 void CEE::PropagateSwitchInfo(SwitchInst *SI) {
810 // Propagate information down each of our non-default case labels. We
811 // don't yet propagate information down the default label, because a
812 // potentially large number of inequality constraints provide less
813 // benefit per unit work than a single equality constraint.
815 Value *cond = SI->getCondition();
816 for (unsigned i = 1; i < SI->getNumSuccessors(); ++i)
817 PropagateEquality(cond, SI->getSuccessorValue(i),
818 getRegionInfo(SI->getSuccessor(i)));
822 // PropagateEquality - If we discover that two values are equal to each other in
823 // a specified region, propagate this knowledge recursively.
825 void CEE::PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI) {
826 if (Op0 == Op1) return; // Gee whiz. Are these really equal each other?
828 if (isa<Constant>(Op0)) // Make sure the constant is always Op1
831 // Make sure we don't already know these are equal, to avoid infinite loops...
832 ValueInfo &VI = RI.getValueInfo(Op0);
834 // Get information about the known relationship between Op0 & Op1
835 Relation &KnownRelation = VI.getRelation(Op1);
837 // If we already know they're equal, don't reprocess...
838 if (KnownRelation.getRelation() == FCmpInst::FCMP_OEQ ||
839 KnownRelation.getRelation() == ICmpInst::ICMP_EQ)
842 // If this is boolean, check to see if one of the operands is a constant. If
843 // it's a constant, then see if the other one is one of a setcc instruction,
844 // an AND, OR, or XOR instruction.
846 ConstantInt *CB = dyn_cast<ConstantInt>(Op1);
847 if (CB && Op1->getType() == Type::Int1Ty) {
848 if (Instruction *Inst = dyn_cast<Instruction>(Op0)) {
849 // If we know that this instruction is an AND instruction, and the
850 // result is true, this means that both operands to the OR are known
851 // to be true as well.
853 if (CB->getZExtValue() && Inst->getOpcode() == Instruction::And) {
854 PropagateEquality(Inst->getOperand(0), CB, RI);
855 PropagateEquality(Inst->getOperand(1), CB, RI);
858 // If we know that this instruction is an OR instruction, and the result
859 // is false, this means that both operands to the OR are know to be
862 if (!CB->getZExtValue() && Inst->getOpcode() == Instruction::Or) {
863 PropagateEquality(Inst->getOperand(0), CB, RI);
864 PropagateEquality(Inst->getOperand(1), CB, RI);
867 // If we know that this instruction is a NOT instruction, we know that
868 // the operand is known to be the inverse of whatever the current
871 if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(Inst))
872 if (BinaryOperator::isNot(BOp))
873 PropagateEquality(BinaryOperator::getNotArgument(BOp),
874 ConstantInt::get(Type::Int1Ty,
875 !CB->getZExtValue()), RI);
877 // If we know the value of a FCmp instruction, propagate the information
878 // about the relation into this region as well.
880 if (FCmpInst *FCI = dyn_cast<FCmpInst>(Inst)) {
881 if (CB->getZExtValue()) { // If we know the condition is true...
882 // Propagate info about the LHS to the RHS & RHS to LHS
883 PropagateRelation(FCI->getPredicate(), FCI->getOperand(0),
884 FCI->getOperand(1), RI);
885 PropagateRelation(FCI->getSwappedPredicate(),
886 FCI->getOperand(1), FCI->getOperand(0), RI);
888 } else { // If we know the condition is false...
889 // We know the opposite of the condition is true...
890 FCmpInst::Predicate C = FCI->getInversePredicate();
892 PropagateRelation(C, FCI->getOperand(0), FCI->getOperand(1), RI);
893 PropagateRelation(FCmpInst::getSwappedPredicate(C),
894 FCI->getOperand(1), FCI->getOperand(0), RI);
898 // If we know the value of a ICmp instruction, propagate the information
899 // about the relation into this region as well.
901 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Inst)) {
902 if (CB->getZExtValue()) { // If we know the condition is true...
903 // Propagate info about the LHS to the RHS & RHS to LHS
904 PropagateRelation(ICI->getPredicate(), ICI->getOperand(0),
905 ICI->getOperand(1), RI);
906 PropagateRelation(ICI->getSwappedPredicate(), ICI->getOperand(1),
907 ICI->getOperand(1), RI);
909 } else { // If we know the condition is false ...
910 // We know the opposite of the condition is true...
911 ICmpInst::Predicate C = ICI->getInversePredicate();
913 PropagateRelation(C, ICI->getOperand(0), ICI->getOperand(1), RI);
914 PropagateRelation(ICmpInst::getSwappedPredicate(C),
915 ICI->getOperand(1), ICI->getOperand(0), RI);
921 // Propagate information about Op0 to Op1 & visa versa
922 PropagateRelation(ICmpInst::ICMP_EQ, Op0, Op1, RI);
923 PropagateRelation(ICmpInst::ICMP_EQ, Op1, Op0, RI);
924 PropagateRelation(FCmpInst::FCMP_OEQ, Op0, Op1, RI);
925 PropagateRelation(FCmpInst::FCMP_OEQ, Op1, Op0, RI);
929 // PropagateRelation - We know that the specified relation is true in all of the
930 // blocks in the specified region. Propagate the information about Op0 and
931 // anything derived from it into this region.
933 void CEE::PropagateRelation(unsigned Opcode, Value *Op0,
934 Value *Op1, RegionInfo &RI) {
935 assert(Op0->getType() == Op1->getType() && "Equal types expected!");
937 // Constants are already pretty well understood. We will apply information
938 // about the constant to Op1 in another call to PropagateRelation.
940 if (isa<Constant>(Op0)) return;
942 // Get the region information for this block to update...
943 ValueInfo &VI = RI.getValueInfo(Op0);
945 // Get information about the known relationship between Op0 & Op1
946 Relation &Op1R = VI.getRelation(Op1);
948 // Quick bailout for common case if we are reprocessing an instruction...
949 if (Op1R.getRelation() == Opcode)
952 // If we already have information that contradicts the current information we
953 // are propagating, ignore this info. Something bad must have happened!
955 if (Op1R.contradicts(Opcode, VI)) {
956 Op1R.contradicts(Opcode, VI);
957 cerr << "Contradiction found for opcode: "
958 << ((isa<ICmpInst>(Op0)||isa<ICmpInst>(Op1)) ?
959 Instruction::getOpcodeName(Instruction::ICmp) :
960 Instruction::getOpcodeName(Opcode))
962 Op1R.print(*cerr.stream());
966 // If the information propagated is new, then we want process the uses of this
967 // instruction to propagate the information down to them.
969 if (Op1R.incorporate(Opcode, VI))
970 UpdateUsersOfValue(Op0, RI);
974 // UpdateUsersOfValue - The information about V in this region has been updated.
975 // Propagate this to all consumers of the value.
977 void CEE::UpdateUsersOfValue(Value *V, RegionInfo &RI) {
978 for (Value::use_iterator I = V->use_begin(), E = V->use_end();
980 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
981 // If this is an instruction using a value that we know something about,
982 // try to propagate information to the value produced by the
983 // instruction. We can only do this if it is an instruction we can
984 // propagate information for (a setcc for example), and we only WANT to
985 // do this if the instruction dominates this region.
987 // If the instruction doesn't dominate this region, then it cannot be
988 // used in this region and we don't care about it. If the instruction
989 // is IN this region, then we will simplify the instruction before we
990 // get to uses of it anyway, so there is no reason to bother with it
991 // here. This check is also effectively checking to make sure that Inst
992 // is in the same function as our region (in case V is a global f.e.).
994 if (DT->properlyDominates(Inst->getParent(), RI.getEntryBlock()))
995 IncorporateInstruction(Inst, RI);
999 // IncorporateInstruction - We just updated the information about one of the
1000 // operands to the specified instruction. Update the information about the
1001 // value produced by this instruction
1003 void CEE::IncorporateInstruction(Instruction *Inst, RegionInfo &RI) {
1004 if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) {
1005 // See if we can figure out a result for this instruction...
1006 Relation::KnownResult Result = getCmpResult(CI, RI);
1007 if (Result != Relation::Unknown) {
1008 PropagateEquality(CI, ConstantInt::get(Type::Int1Ty, Result != 0), RI);
1014 // ComputeReplacements - Some values are known to be equal to other values in a
1015 // region. For example if there is a comparison of equality between a variable
1016 // X and a constant C, we can replace all uses of X with C in the region we are
1017 // interested in. We generalize this replacement to replace variables with
1018 // other variables if they are equal and there is a variable with lower rank
1019 // than the current one. This offers a canonicalizing property that exposes
1020 // more redundancies for later transformations to take advantage of.
1022 void CEE::ComputeReplacements(RegionInfo &RI) {
1023 // Loop over all of the values in the region info map...
1024 for (RegionInfo::iterator I = RI.begin(), E = RI.end(); I != E; ++I) {
1025 ValueInfo &VI = I->second;
1027 // If we know that this value is a particular constant, set Replacement to
1029 Value *Replacement = 0;
1030 const APInt * Rplcmnt = VI.getBounds().getSingleElement();
1032 Replacement = ConstantInt::get(*Rplcmnt);
1034 // If this value is not known to be some constant, figure out the lowest
1035 // rank value that it is known to be equal to (if anything).
1037 if (Replacement == 0) {
1038 // Find out if there are any equality relationships with values of lower
1039 // rank than VI itself...
1040 unsigned MinRank = getRank(I->first);
1042 // Loop over the relationships known about Op0.
1043 const std::vector<Relation> &Relationships = VI.getRelationships();
1044 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
1045 if (Relationships[i].getRelation() == FCmpInst::FCMP_OEQ) {
1046 unsigned R = getRank(Relationships[i].getValue());
1049 Replacement = Relationships[i].getValue();
1052 else if (Relationships[i].getRelation() == ICmpInst::ICMP_EQ) {
1053 unsigned R = getRank(Relationships[i].getValue());
1056 Replacement = Relationships[i].getValue();
1061 // If we found something to replace this value with, keep track of it.
1063 VI.setReplacement(Replacement);
1067 // SimplifyBasicBlock - Given information about values in region RI, simplify
1068 // the instructions in the specified basic block.
1070 bool CEE::SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI) {
1071 bool Changed = false;
1072 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ) {
1073 Instruction *Inst = I++;
1075 // Convert instruction arguments to canonical forms...
1076 Changed |= SimplifyInstruction(Inst, RI);
1078 if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) {
1079 // Try to simplify a setcc instruction based on inherited information
1080 Relation::KnownResult Result = getCmpResult(CI, RI);
1081 if (Result != Relation::Unknown) {
1082 DEBUG(cerr << "Replacing icmp with " << Result
1083 << " constant: " << *CI);
1085 CI->replaceAllUsesWith(ConstantInt::get(Type::Int1Ty, (bool)Result));
1086 // The instruction is now dead, remove it from the program.
1087 CI->getParent()->getInstList().erase(CI);
1097 // SimplifyInstruction - Inspect the operands of the instruction, converting
1098 // them to their canonical form if possible. This takes care of, for example,
1099 // replacing a value 'X' with a constant 'C' if the instruction in question is
1100 // dominated by a true seteq 'X', 'C'.
1102 bool CEE::SimplifyInstruction(Instruction *I, const RegionInfo &RI) {
1103 bool Changed = false;
1105 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1106 if (const ValueInfo *VI = RI.requestValueInfo(I->getOperand(i)))
1107 if (Value *Repl = VI->getReplacement()) {
1108 // If we know if a replacement with lower rank than Op0, make the
1110 DOUT << "In Inst: " << *I << " Replacing operand #" << i
1111 << " with " << *Repl << "\n";
1112 I->setOperand(i, Repl);
1120 // getCmpResult - Try to simplify a cmp instruction based on information
1121 // inherited from a dominating icmp instruction. V is one of the operands to
1122 // the icmp instruction, and VI is the set of information known about it. We
1123 // take two cases into consideration here. If the comparison is against a
1124 // constant value, we can use the constant range to see if the comparison is
1125 // possible to succeed. If it is not a comparison against a constant, we check
1126 // to see if there is a known relationship between the two values. If so, we
1127 // may be able to eliminate the check.
1129 Relation::KnownResult CEE::getCmpResult(CmpInst *CI,
1130 const RegionInfo &RI) {
1131 Value *Op0 = CI->getOperand(0), *Op1 = CI->getOperand(1);
1132 unsigned short predicate = CI->getPredicate();
1134 if (isa<Constant>(Op0)) {
1135 if (isa<Constant>(Op1)) {
1136 if (Constant *Result = ConstantFoldInstruction(CI)) {
1137 // Wow, this is easy, directly eliminate the ICmpInst.
1138 DEBUG(cerr << "Replacing cmp with constant fold: " << *CI);
1139 return cast<ConstantInt>(Result)->getZExtValue()
1140 ? Relation::KnownTrue : Relation::KnownFalse;
1143 // We want to swap this instruction so that operand #0 is the constant.
1144 std::swap(Op0, Op1);
1145 if (isa<ICmpInst>(CI))
1146 predicate = cast<ICmpInst>(CI)->getSwappedPredicate();
1148 predicate = cast<FCmpInst>(CI)->getSwappedPredicate();
1152 // Try to figure out what the result of this comparison will be...
1153 Relation::KnownResult Result = Relation::Unknown;
1155 // We have to know something about the relationship to prove anything...
1156 if (const ValueInfo *Op0VI = RI.requestValueInfo(Op0)) {
1158 // At this point, we know that if we have a constant argument that it is in
1159 // Op1. Check to see if we know anything about comparing value with a
1160 // constant, and if we can use this info to fold the icmp.
1162 if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
1163 // Check to see if we already know the result of this comparison...
1164 ICmpInst::Predicate ipred = ICmpInst::Predicate(predicate);
1165 ConstantRange R = ICmpInst::makeConstantRange(ipred, C->getValue());
1166 ConstantRange Int = R.intersectWith(Op0VI->getBounds());
1168 // If the intersection of the two ranges is empty, then the condition
1169 // could never be true!
1171 if (Int.isEmptySet()) {
1172 Result = Relation::KnownFalse;
1174 // Otherwise, if VI.getBounds() (the possible values) is a subset of R
1175 // (the allowed values) then we know that the condition must always be
1178 } else if (Int == Op0VI->getBounds()) {
1179 Result = Relation::KnownTrue;
1182 // If we are here, we know that the second argument is not a constant
1183 // integral. See if we know anything about Op0 & Op1 that allows us to
1184 // fold this anyway.
1186 // Do we have value information about Op0 and a relation to Op1?
1187 if (const Relation *Op2R = Op0VI->requestRelation(Op1))
1188 Result = Op2R->getImpliedResult(predicate);
1194 //===----------------------------------------------------------------------===//
1195 // Relation Implementation
1196 //===----------------------------------------------------------------------===//
1198 // contradicts - Return true if the relationship specified by the operand
1199 // contradicts already known information.
1201 bool Relation::contradicts(unsigned Op,
1202 const ValueInfo &VI) const {
1203 assert (Op != Instruction::Add && "Invalid relation argument!");
1205 // If this is a relationship with a constant, make sure that this relationship
1206 // does not contradict properties known about the bounds of the constant.
1208 if (ConstantInt *C = dyn_cast<ConstantInt>(Val))
1209 if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
1210 Op <= ICmpInst::LAST_ICMP_PREDICATE) {
1211 ICmpInst::Predicate ipred = ICmpInst::Predicate(Op);
1212 if (ICmpInst::makeConstantRange(ipred, C->getValue())
1213 .intersectWith(VI.getBounds()).isEmptySet())
1218 default: assert(0 && "Unknown Relationship code!");
1219 case Instruction::Add: return false; // Nothing known, nothing contradicts
1220 case ICmpInst::ICMP_EQ:
1221 return Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_SLT ||
1222 Op == ICmpInst::ICMP_UGT || Op == ICmpInst::ICMP_SGT ||
1223 Op == ICmpInst::ICMP_NE;
1224 case ICmpInst::ICMP_NE: return Op == ICmpInst::ICMP_EQ;
1225 case ICmpInst::ICMP_ULE:
1226 case ICmpInst::ICMP_SLE: return Op == ICmpInst::ICMP_UGT ||
1227 Op == ICmpInst::ICMP_SGT;
1228 case ICmpInst::ICMP_UGE:
1229 case ICmpInst::ICMP_SGE: return Op == ICmpInst::ICMP_ULT ||
1230 Op == ICmpInst::ICMP_SLT;
1231 case ICmpInst::ICMP_ULT:
1232 case ICmpInst::ICMP_SLT:
1233 return Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_UGT ||
1234 Op == ICmpInst::ICMP_SGT || Op == ICmpInst::ICMP_UGE ||
1235 Op == ICmpInst::ICMP_SGE;
1236 case ICmpInst::ICMP_UGT:
1237 case ICmpInst::ICMP_SGT:
1238 return Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_ULT ||
1239 Op == ICmpInst::ICMP_SLT || Op == ICmpInst::ICMP_ULE ||
1240 Op == ICmpInst::ICMP_SLE;
1241 case FCmpInst::FCMP_OEQ:
1242 return Op == FCmpInst::FCMP_OLT || Op == FCmpInst::FCMP_OGT ||
1243 Op == FCmpInst::FCMP_ONE;
1244 case FCmpInst::FCMP_ONE: return Op == FCmpInst::FCMP_OEQ;
1245 case FCmpInst::FCMP_OLE: return Op == FCmpInst::FCMP_OGT;
1246 case FCmpInst::FCMP_OGE: return Op == FCmpInst::FCMP_OLT;
1247 case FCmpInst::FCMP_OLT:
1248 return Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OGT ||
1249 Op == FCmpInst::FCMP_OGE;
1250 case FCmpInst::FCMP_OGT:
1251 return Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OLT ||
1252 Op == FCmpInst::FCMP_OLE;
1256 // incorporate - Incorporate information in the argument into this relation
1257 // entry. This assumes that the information doesn't contradict itself. If any
1258 // new information is gained, true is returned, otherwise false is returned to
1259 // indicate that nothing was updated.
1261 bool Relation::incorporate(unsigned Op, ValueInfo &VI) {
1262 assert(!contradicts(Op, VI) &&
1263 "Cannot incorporate contradictory information!");
1265 // If this is a relationship with a constant, make sure that we update the
1266 // range that is possible for the value to have...
1268 if (ConstantInt *C = dyn_cast<ConstantInt>(Val))
1269 if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
1270 Op <= ICmpInst::LAST_ICMP_PREDICATE) {
1271 ICmpInst::Predicate ipred = ICmpInst::Predicate(Op);
1273 ICmpInst::makeConstantRange(ipred, C->getValue())
1274 .intersectWith(VI.getBounds());
1278 default: assert(0 && "Unknown prior value!");
1279 case Instruction::Add: Rel = Op; return true;
1280 case ICmpInst::ICMP_EQ:
1281 case ICmpInst::ICMP_NE:
1282 case ICmpInst::ICMP_ULT:
1283 case ICmpInst::ICMP_SLT:
1284 case ICmpInst::ICMP_UGT:
1285 case ICmpInst::ICMP_SGT: return false; // Nothing is more precise
1286 case ICmpInst::ICMP_ULE:
1287 case ICmpInst::ICMP_SLE:
1288 if (Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_ULT ||
1289 Op == ICmpInst::ICMP_SLT) {
1292 } else if (Op == ICmpInst::ICMP_NE) {
1293 Rel = Rel == ICmpInst::ICMP_ULE ? ICmpInst::ICMP_ULT :
1298 case ICmpInst::ICMP_UGE:
1299 case ICmpInst::ICMP_SGE:
1300 if (Op == ICmpInst::ICMP_EQ || ICmpInst::ICMP_UGT ||
1301 Op == ICmpInst::ICMP_SGT) {
1304 } else if (Op == ICmpInst::ICMP_NE) {
1305 Rel = Rel == ICmpInst::ICMP_UGE ? ICmpInst::ICMP_UGT :
1310 case FCmpInst::FCMP_OEQ: return false; // Nothing is more precise
1311 case FCmpInst::FCMP_ONE: return false; // Nothing is more precise
1312 case FCmpInst::FCMP_OLT: return false; // Nothing is more precise
1313 case FCmpInst::FCMP_OGT: return false; // Nothing is more precise
1314 case FCmpInst::FCMP_OLE:
1315 if (Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OLT) {
1318 } else if (Op == FCmpInst::FCMP_ONE) {
1319 Rel = FCmpInst::FCMP_OLT;
1323 case FCmpInst::FCMP_OGE:
1324 if (Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OGT) {
1327 } else if (Op == FCmpInst::FCMP_ONE) {
1328 Rel = FCmpInst::FCMP_OGT;
1335 // getImpliedResult - If this relationship between two values implies that
1336 // the specified relationship is true or false, return that. If we cannot
1337 // determine the result required, return Unknown.
1339 Relation::KnownResult
1340 Relation::getImpliedResult(unsigned Op) const {
1341 if (Rel == Op) return KnownTrue;
1342 if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
1343 Op <= ICmpInst::LAST_ICMP_PREDICATE) {
1344 if (Rel == unsigned(ICmpInst::getInversePredicate(ICmpInst::Predicate(Op))))
1346 } else if (Op <= FCmpInst::LAST_FCMP_PREDICATE) {
1347 if (Rel == unsigned(FCmpInst::getInversePredicate(FCmpInst::Predicate(Op))))
1352 default: assert(0 && "Unknown prior value!");
1353 case ICmpInst::ICMP_EQ:
1354 if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_SLE ||
1355 Op == ICmpInst::ICMP_UGE || Op == ICmpInst::ICMP_SGE) return KnownTrue;
1356 if (Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_SLT ||
1357 Op == ICmpInst::ICMP_UGT || Op == ICmpInst::ICMP_SGT) return KnownFalse;
1359 case ICmpInst::ICMP_ULT:
1360 case ICmpInst::ICMP_SLT:
1361 if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_SLE ||
1362 Op == ICmpInst::ICMP_NE) return KnownTrue;
1363 if (Op == ICmpInst::ICMP_EQ) return KnownFalse;
1365 case ICmpInst::ICMP_UGT:
1366 case ICmpInst::ICMP_SGT:
1367 if (Op == ICmpInst::ICMP_UGE || Op == ICmpInst::ICMP_SGE ||
1368 Op == ICmpInst::ICMP_NE) return KnownTrue;
1369 if (Op == ICmpInst::ICMP_EQ) return KnownFalse;
1371 case FCmpInst::FCMP_OEQ:
1372 if (Op == FCmpInst::FCMP_OLE || Op == FCmpInst::FCMP_OGE) return KnownTrue;
1373 if (Op == FCmpInst::FCMP_OLT || Op == FCmpInst::FCMP_OGT) return KnownFalse;
1375 case FCmpInst::FCMP_OLT:
1376 if (Op == FCmpInst::FCMP_ONE || Op == FCmpInst::FCMP_OLE) return KnownTrue;
1377 if (Op == FCmpInst::FCMP_OEQ) return KnownFalse;
1379 case FCmpInst::FCMP_OGT:
1380 if (Op == FCmpInst::FCMP_ONE || Op == FCmpInst::FCMP_OGE) return KnownTrue;
1381 if (Op == FCmpInst::FCMP_OEQ) return KnownFalse;
1383 case ICmpInst::ICMP_NE:
1384 case ICmpInst::ICMP_SLE:
1385 case ICmpInst::ICMP_ULE:
1386 case ICmpInst::ICMP_UGE:
1387 case ICmpInst::ICMP_SGE:
1388 case FCmpInst::FCMP_ONE:
1389 case FCmpInst::FCMP_OLE:
1390 case FCmpInst::FCMP_OGE:
1391 case FCmpInst::FCMP_FALSE:
1392 case FCmpInst::FCMP_ORD:
1393 case FCmpInst::FCMP_UNO:
1394 case FCmpInst::FCMP_UEQ:
1395 case FCmpInst::FCMP_UGT:
1396 case FCmpInst::FCMP_UGE:
1397 case FCmpInst::FCMP_ULT:
1398 case FCmpInst::FCMP_ULE:
1399 case FCmpInst::FCMP_UNE:
1400 case FCmpInst::FCMP_TRUE:
1407 //===----------------------------------------------------------------------===//
1408 // Printing Support...
1409 //===----------------------------------------------------------------------===//
1411 // print - Implement the standard print form to print out analysis information.
1412 void CEE::print(std::ostream &O, const Module *M) const {
1413 O << "\nPrinting Correlated Expression Info:\n";
1414 for (std::map<BasicBlock*, RegionInfo>::const_iterator I =
1415 RegionInfoMap.begin(), E = RegionInfoMap.end(); I != E; ++I)
1419 // print - Output information about this region...
1420 void RegionInfo::print(std::ostream &OS) const {
1421 if (ValueMap.empty()) return;
1423 OS << " RegionInfo for basic block: " << BB->getName() << "\n";
1424 for (std::map<Value*, ValueInfo>::const_iterator
1425 I = ValueMap.begin(), E = ValueMap.end(); I != E; ++I)
1426 I->second.print(OS, I->first);
1430 // print - Output information about this value relation...
1431 void ValueInfo::print(std::ostream &OS, Value *V) const {
1432 if (Relationships.empty()) return;
1435 OS << " ValueInfo for: ";
1436 WriteAsOperand(OS, V);
1438 OS << "\n Bounds = " << Bounds << "\n";
1440 OS << " Replacement = ";
1441 WriteAsOperand(OS, Replacement);
1444 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
1445 Relationships[i].print(OS);
1448 // print - Output this relation to the specified stream
1449 void Relation::print(std::ostream &OS) const {
1452 default: OS << "*UNKNOWN*"; break;
1453 case ICmpInst::ICMP_EQ:
1454 case FCmpInst::FCMP_ORD:
1455 case FCmpInst::FCMP_UEQ:
1456 case FCmpInst::FCMP_OEQ: OS << "== "; break;
1457 case ICmpInst::ICMP_NE:
1458 case FCmpInst::FCMP_UNO:
1459 case FCmpInst::FCMP_UNE:
1460 case FCmpInst::FCMP_ONE: OS << "!= "; break;
1461 case ICmpInst::ICMP_ULT:
1462 case ICmpInst::ICMP_SLT:
1463 case FCmpInst::FCMP_ULT:
1464 case FCmpInst::FCMP_OLT: OS << "< "; break;
1465 case ICmpInst::ICMP_UGT:
1466 case ICmpInst::ICMP_SGT:
1467 case FCmpInst::FCMP_UGT:
1468 case FCmpInst::FCMP_OGT: OS << "> "; break;
1469 case ICmpInst::ICMP_ULE:
1470 case ICmpInst::ICMP_SLE:
1471 case FCmpInst::FCMP_ULE:
1472 case FCmpInst::FCMP_OLE: OS << "<= "; break;
1473 case ICmpInst::ICMP_UGE:
1474 case ICmpInst::ICMP_SGE:
1475 case FCmpInst::FCMP_UGE:
1476 case FCmpInst::FCMP_OGE: OS << ">= "; break;
1479 WriteAsOperand(OS, Val);
1483 // Don't inline these methods or else we won't be able to call them from GDB!
1484 void Relation::dump() const { print(*cerr.stream()); }
1485 void ValueInfo::dump() const { print(*cerr.stream(), 0); }
1486 void RegionInfo::dump() const { print(*cerr.stream()); }