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/Analysis/Dominators.h"
37 #include "llvm/Assembly/Writer.h"
38 #include "llvm/Transforms/Utils/Local.h"
39 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
40 #include "llvm/Support/ConstantRange.h"
41 #include "llvm/Support/CFG.h"
42 #include "llvm/Support/Debug.h"
43 #include "llvm/ADT/PostOrderIterator.h"
44 #include "llvm/ADT/Statistic.h"
48 STATISTIC(NumCmpRemoved, "Number of cmp instruction eliminated");
49 STATISTIC(NumOperandsCann, "Number of operands canonicalized");
50 STATISTIC(BranchRevectors, "Number of branches revectored");
55 Value *Val; // Relation to what value?
56 unsigned Rel; // SetCC or ICmp relation, or Add if no information
58 Relation(Value *V) : Val(V), Rel(Instruction::Add) {}
59 bool operator<(const Relation &R) const { return Val < R.Val; }
60 Value *getValue() const { return Val; }
61 unsigned getRelation() const { return Rel; }
63 // contradicts - Return true if the relationship specified by the operand
64 // contradicts already known information.
66 bool contradicts(unsigned Rel, const ValueInfo &VI) const;
68 // incorporate - Incorporate information in the argument into this relation
69 // entry. This assumes that the information doesn't contradict itself. If
70 // any new information is gained, true is returned, otherwise false is
71 // returned to indicate that nothing was updated.
73 bool incorporate(unsigned Rel, ValueInfo &VI);
75 // KnownResult - Whether or not this condition determines the result of a
76 // setcc or icmp in the program. False & True are intentionally 0 & 1
77 // so we can convert to bool by casting after checking for unknown.
79 enum KnownResult { KnownFalse = 0, KnownTrue = 1, Unknown = 2 };
81 // getImpliedResult - If this relationship between two values implies that
82 // the specified relationship is true or false, return that. If we cannot
83 // determine the result required, return Unknown.
85 KnownResult getImpliedResult(unsigned Rel) const;
87 // print - Output this relation to the specified stream
88 void print(std::ostream &OS) const;
93 // ValueInfo - One instance of this record exists for every value with
94 // relationships between other values. It keeps track of all of the
95 // relationships to other values in the program (specified with Relation) that
96 // are known to be valid in a region.
99 // RelationShips - this value is know to have the specified relationships to
100 // other values. There can only be one entry per value, and this list is
101 // kept sorted by the Val field.
102 std::vector<Relation> Relationships;
104 // If information about this value is known or propagated from constant
105 // expressions, this range contains the possible values this value may hold.
106 ConstantRange Bounds;
108 // If we find that this value is equal to another value that has a lower
109 // rank, this value is used as it's replacement.
113 ValueInfo(const Type *Ty)
114 : Bounds(Ty->isIntegral() ? Ty : Type::Int32Ty), Replacement(0) {}
116 // getBounds() - Return the constant bounds of the value...
117 const ConstantRange &getBounds() const { return Bounds; }
118 ConstantRange &getBounds() { return Bounds; }
120 const std::vector<Relation> &getRelationships() { return Relationships; }
122 // getReplacement - Return the value this value is to be replaced with if it
123 // exists, otherwise return null.
125 Value *getReplacement() const { return Replacement; }
127 // setReplacement - Used by the replacement calculation pass to figure out
128 // what to replace this value with, if anything.
130 void setReplacement(Value *Repl) { Replacement = Repl; }
132 // getRelation - return the relationship entry for the specified value.
133 // This can invalidate references to other Relations, so use it carefully.
135 Relation &getRelation(Value *V) {
136 // Binary search for V's entry...
137 std::vector<Relation>::iterator I =
138 std::lower_bound(Relationships.begin(), Relationships.end(),
141 // If we found the entry, return it...
142 if (I != Relationships.end() && I->getValue() == V)
145 // Insert and return the new relationship...
146 return *Relationships.insert(I, V);
149 const Relation *requestRelation(Value *V) const {
150 // Binary search for V's entry...
151 std::vector<Relation>::const_iterator I =
152 std::lower_bound(Relationships.begin(), Relationships.end(),
154 if (I != Relationships.end() && I->getValue() == V)
159 // print - Output information about this value relation...
160 void print(std::ostream &OS, Value *V) const;
164 // RegionInfo - Keeps track of all of the value relationships for a region. A
165 // region is the are dominated by a basic block. RegionInfo's keep track of
166 // the RegionInfo for their dominator, because anything known in a dominator
167 // is known to be true in a dominated block as well.
172 // ValueMap - Tracks the ValueInformation known for this region
173 typedef std::map<Value*, ValueInfo> ValueMapTy;
176 RegionInfo(BasicBlock *bb) : BB(bb) {}
178 // getEntryBlock - Return the block that dominates all of the members of
180 BasicBlock *getEntryBlock() const { return BB; }
182 // empty - return true if this region has no information known about it.
183 bool empty() const { return ValueMap.empty(); }
185 const RegionInfo &operator=(const RegionInfo &RI) {
186 ValueMap = RI.ValueMap;
190 // print - Output information about this region...
191 void print(std::ostream &OS) const;
194 // Allow external access.
195 typedef ValueMapTy::iterator iterator;
196 iterator begin() { return ValueMap.begin(); }
197 iterator end() { return ValueMap.end(); }
199 ValueInfo &getValueInfo(Value *V) {
200 ValueMapTy::iterator I = ValueMap.lower_bound(V);
201 if (I != ValueMap.end() && I->first == V) return I->second;
202 return ValueMap.insert(I, std::make_pair(V, V->getType()))->second;
205 const ValueInfo *requestValueInfo(Value *V) const {
206 ValueMapTy::const_iterator I = ValueMap.find(V);
207 if (I != ValueMap.end()) return &I->second;
211 /// removeValueInfo - Remove anything known about V from our records. This
212 /// works whether or not we know anything about V.
214 void removeValueInfo(Value *V) {
219 /// CEE - Correlated Expression Elimination
220 class CEE : public FunctionPass {
221 std::map<Value*, unsigned> RankMap;
222 std::map<BasicBlock*, RegionInfo> RegionInfoMap;
226 virtual bool runOnFunction(Function &F);
228 // We don't modify the program, so we preserve all analyses
229 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
230 AU.addRequired<ETForest>();
231 AU.addRequired<DominatorTree>();
232 AU.addRequiredID(BreakCriticalEdgesID);
235 // print - Implement the standard print form to print out analysis
237 virtual void print(std::ostream &O, const Module *M) const;
240 RegionInfo &getRegionInfo(BasicBlock *BB) {
241 std::map<BasicBlock*, RegionInfo>::iterator I
242 = RegionInfoMap.lower_bound(BB);
243 if (I != RegionInfoMap.end() && I->first == BB) return I->second;
244 return RegionInfoMap.insert(I, std::make_pair(BB, BB))->second;
247 void BuildRankMap(Function &F);
248 unsigned getRank(Value *V) const {
249 if (isa<Constant>(V)) return 0;
250 std::map<Value*, unsigned>::const_iterator I = RankMap.find(V);
251 if (I != RankMap.end()) return I->second;
252 return 0; // Must be some other global thing
255 bool TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks);
257 bool ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
260 void ForwardSuccessorTo(TerminatorInst *TI, unsigned Succ, BasicBlock *D,
262 void ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
263 BasicBlock *RegionDominator);
264 void CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
265 std::vector<BasicBlock*> &RegionExitBlocks);
266 void InsertRegionExitMerges(PHINode *NewPHI, Instruction *OldVal,
267 const std::vector<BasicBlock*> &RegionExitBlocks);
269 void PropagateBranchInfo(BranchInst *BI);
270 void PropagateSwitchInfo(SwitchInst *SI);
271 void PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI);
272 void PropagateRelation(unsigned Opcode, Value *Op0,
273 Value *Op1, RegionInfo &RI);
274 void UpdateUsersOfValue(Value *V, RegionInfo &RI);
275 void IncorporateInstruction(Instruction *Inst, RegionInfo &RI);
276 void ComputeReplacements(RegionInfo &RI);
278 // getCmpResult - Given a icmp instruction, determine if the result is
279 // determined by facts we already know about the region under analysis.
280 // Return KnownTrue, KnownFalse, or UnKnown based on what we can determine.
281 Relation::KnownResult getCmpResult(CmpInst *ICI, const RegionInfo &RI);
283 bool SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI);
284 bool SimplifyInstruction(Instruction *Inst, const RegionInfo &RI);
286 RegisterPass<CEE> X("cee", "Correlated Expression Elimination");
289 FunctionPass *llvm::createCorrelatedExpressionEliminationPass() {
294 bool CEE::runOnFunction(Function &F) {
295 // Build a rank map for the function...
298 // Traverse the dominator tree, computing information for each node in the
299 // tree. Note that our traversal will not even touch unreachable basic
301 EF = &getAnalysis<ETForest>();
302 DT = &getAnalysis<DominatorTree>();
304 std::set<BasicBlock*> VisitedBlocks;
305 bool Changed = TransformRegion(&F.getEntryBlock(), VisitedBlocks);
307 RegionInfoMap.clear();
312 // TransformRegion - Transform the region starting with BB according to the
313 // calculated region information for the block. Transforming the region
314 // involves analyzing any information this block provides to successors,
315 // propagating the information to successors, and finally transforming
318 // This method processes the function in depth first order, which guarantees
319 // that we process the immediate dominator of a block before the block itself.
320 // Because we are passing information from immediate dominators down to
321 // dominatees, we obviously have to process the information source before the
322 // information consumer.
324 bool CEE::TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks){
325 // Prevent infinite recursion...
326 if (VisitedBlocks.count(BB)) return false;
327 VisitedBlocks.insert(BB);
329 // Get the computed region information for this block...
330 RegionInfo &RI = getRegionInfo(BB);
332 // Compute the replacement information for this block...
333 ComputeReplacements(RI);
335 // If debugging, print computed region information...
336 DEBUG(RI.print(*cerr.stream()));
338 // Simplify the contents of this block...
339 bool Changed = SimplifyBasicBlock(*BB, RI);
341 // Get the terminator of this basic block...
342 TerminatorInst *TI = BB->getTerminator();
344 // Loop over all of the blocks that this block is the immediate dominator for.
345 // Because all information known in this region is also known in all of the
346 // blocks that are dominated by this one, we can safely propagate the
347 // information down now.
349 DominatorTree::Node *BBN = (*DT)[BB];
350 if (!RI.empty()) // Time opt: only propagate if we can change something
351 for (unsigned i = 0, e = BBN->getChildren().size(); i != e; ++i) {
352 BasicBlock *Dominated = BBN->getChildren()[i]->getBlock();
353 assert(RegionInfoMap.find(Dominated) == RegionInfoMap.end() &&
354 "RegionInfo should be calculated in dominanace order!");
355 getRegionInfo(Dominated) = RI;
358 // Now that all of our successors have information if they deserve it,
359 // propagate any information our terminator instruction finds to our
361 if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
362 if (BI->isConditional())
363 PropagateBranchInfo(BI);
364 } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) {
365 PropagateSwitchInfo(SI);
368 // If this is a branch to a block outside our region that simply performs
369 // another conditional branch, one whose outcome is known inside of this
370 // region, then vector this outgoing edge directly to the known destination.
372 for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i)
373 while (ForwardCorrelatedEdgeDestination(TI, i, RI)) {
378 // Now that all of our successors have information, recursively process them.
379 for (unsigned i = 0, e = BBN->getChildren().size(); i != e; ++i)
380 Changed |= TransformRegion(BBN->getChildren()[i]->getBlock(),VisitedBlocks);
385 // isBlockSimpleEnoughForCheck to see if the block is simple enough for us to
386 // revector the conditional branch in the bottom of the block, do so now.
388 static bool isBlockSimpleEnough(BasicBlock *BB) {
389 assert(isa<BranchInst>(BB->getTerminator()));
390 BranchInst *BI = cast<BranchInst>(BB->getTerminator());
391 assert(BI->isConditional());
393 // Check the common case first: empty block, or block with just a setcc.
394 if (BB->size() == 1 ||
395 (BB->size() == 2 && &BB->front() == BI->getCondition() &&
396 BI->getCondition()->hasOneUse()))
399 // Check the more complex case now...
400 BasicBlock::iterator I = BB->begin();
402 // FIXME: This should be reenabled once the regression with SIM is fixed!
404 // PHI Nodes are ok, just skip over them...
405 while (isa<PHINode>(*I)) ++I;
408 // Accept the setcc instruction...
409 if (&*I == BI->getCondition())
412 // Nothing else is acceptable here yet. We must not revector... unless we are
413 // at the terminator instruction.
421 bool CEE::ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo,
423 // If this successor is a simple block not in the current region, which
424 // contains only a conditional branch, we decide if the outcome of the branch
425 // can be determined from information inside of the region. Instead of going
426 // to this block, we can instead go to the destination we know is the right
430 // Check to see if we dominate the block. If so, this block will get the
431 // condition turned to a constant anyway.
433 //if (EF->dominates(RI.getEntryBlock(), BB))
436 BasicBlock *BB = TI->getParent();
438 // Get the destination block of this edge...
439 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
441 // Make sure that the block ends with a conditional branch and is simple
442 // enough for use to be able to revector over.
443 BranchInst *BI = dyn_cast<BranchInst>(OldSucc->getTerminator());
444 if (BI == 0 || !BI->isConditional() || !isBlockSimpleEnough(OldSucc))
447 // We can only forward the branch over the block if the block ends with a
448 // cmp we can determine the outcome for.
450 // FIXME: we can make this more generic. Code below already handles more
452 if (!isa<CmpInst>(BI->getCondition()))
455 // Make a new RegionInfo structure so that we can simulate the effect of the
456 // PHI nodes in the block we are skipping over...
458 RegionInfo NewRI(RI);
460 // Remove value information for all of the values we are simulating... to make
461 // sure we don't have any stale information.
462 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
463 if (I->getType() != Type::VoidTy)
464 NewRI.removeValueInfo(I);
466 // Put the newly discovered information into the RegionInfo...
467 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I)
468 if (PHINode *PN = dyn_cast<PHINode>(I)) {
469 int OpNum = PN->getBasicBlockIndex(BB);
470 assert(OpNum != -1 && "PHI doesn't have incoming edge for predecessor!?");
471 PropagateEquality(PN, PN->getIncomingValue(OpNum), NewRI);
472 } else if (CmpInst *CI = dyn_cast<CmpInst>(I)) {
473 Relation::KnownResult Res = getCmpResult(CI, NewRI);
474 if (Res == Relation::Unknown) return false;
475 PropagateEquality(CI, ConstantBool::get(Res), NewRI);
477 assert(isa<BranchInst>(*I) && "Unexpected instruction type!");
480 // Compute the facts implied by what we have discovered...
481 ComputeReplacements(NewRI);
483 ValueInfo &PredicateVI = NewRI.getValueInfo(BI->getCondition());
484 if (PredicateVI.getReplacement() &&
485 isa<Constant>(PredicateVI.getReplacement()) &&
486 !isa<GlobalValue>(PredicateVI.getReplacement())) {
487 ConstantBool *CB = cast<ConstantBool>(PredicateVI.getReplacement());
489 // Forward to the successor that corresponds to the branch we will take.
490 ForwardSuccessorTo(TI, SuccNo, BI->getSuccessor(!CB->getValue()), NewRI);
497 static Value *getReplacementOrValue(Value *V, RegionInfo &RI) {
498 if (const ValueInfo *VI = RI.requestValueInfo(V))
499 if (Value *Repl = VI->getReplacement())
504 /// ForwardSuccessorTo - We have found that we can forward successor # 'SuccNo'
505 /// of Terminator 'TI' to the 'Dest' BasicBlock. This method performs the
506 /// mechanics of updating SSA information and revectoring the branch.
508 void CEE::ForwardSuccessorTo(TerminatorInst *TI, unsigned SuccNo,
509 BasicBlock *Dest, RegionInfo &RI) {
510 // If there are any PHI nodes in the Dest BB, we must duplicate the entry
511 // in the PHI node for the old successor to now include an entry from the
512 // current basic block.
514 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
515 BasicBlock *BB = TI->getParent();
517 DOUT << "Forwarding branch in basic block %" << BB->getName()
518 << " from block %" << OldSucc->getName() << " to block %"
519 << Dest->getName() << "\n"
520 << "Before forwarding: " << *BB->getParent();
522 // Because we know that there cannot be critical edges in the flow graph, and
523 // that OldSucc has multiple outgoing edges, this means that Dest cannot have
524 // multiple incoming edges.
527 pred_iterator DPI = pred_begin(Dest); ++DPI;
528 assert(DPI == pred_end(Dest) && "Critical edge found!!");
531 // Loop over any PHI nodes in the destination, eliminating them, because they
532 // may only have one input.
534 while (PHINode *PN = dyn_cast<PHINode>(&Dest->front())) {
535 assert(PN->getNumIncomingValues() == 1 && "Crit edge found!");
536 // Eliminate the PHI node
537 PN->replaceAllUsesWith(PN->getIncomingValue(0));
538 Dest->getInstList().erase(PN);
541 // If there are values defined in the "OldSucc" basic block, we need to insert
542 // PHI nodes in the regions we are dealing with to emulate them. This can
543 // insert dead phi nodes, but it is more trouble to see if they are used than
544 // to just blindly insert them.
546 if (EF->dominates(OldSucc, Dest)) {
547 // RegionExitBlocks - Find all of the blocks that are not dominated by Dest,
548 // but have predecessors that are. Additionally, prune down the set to only
549 // include blocks that are dominated by OldSucc as well.
551 std::vector<BasicBlock*> RegionExitBlocks;
552 CalculateRegionExitBlocks(Dest, OldSucc, RegionExitBlocks);
554 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end();
556 if (I->getType() != Type::VoidTy) {
557 // Create and insert the PHI node into the top of Dest.
558 PHINode *NewPN = new PHINode(I->getType(), I->getName()+".fw_merge",
560 // There is definitely an edge from OldSucc... add the edge now
561 NewPN->addIncoming(I, OldSucc);
563 // There is also an edge from BB now, add the edge with the calculated
564 // value from the RI.
565 NewPN->addIncoming(getReplacementOrValue(I, RI), BB);
567 // Make everything in the Dest region use the new PHI node now...
568 ReplaceUsesOfValueInRegion(I, NewPN, Dest);
570 // Make sure that exits out of the region dominated by NewPN get PHI
571 // nodes that merge the values as appropriate.
572 InsertRegionExitMerges(NewPN, I, RegionExitBlocks);
576 // If there were PHI nodes in OldSucc, we need to remove the entry for this
577 // edge from the PHI node, and we need to replace any references to the PHI
578 // node with a new value.
580 for (BasicBlock::iterator I = OldSucc->begin(); isa<PHINode>(I); ) {
581 PHINode *PN = cast<PHINode>(I);
583 // Get the value flowing across the old edge and remove the PHI node entry
584 // for this edge: we are about to remove the edge! Don't remove the PHI
585 // node yet though if this is the last edge into it.
586 Value *EdgeValue = PN->removeIncomingValue(BB, false);
588 // Make sure that anything that used to use PN now refers to EdgeValue
589 ReplaceUsesOfValueInRegion(PN, EdgeValue, Dest);
591 // If there is only one value left coming into the PHI node, replace the PHI
592 // node itself with the one incoming value left.
594 if (PN->getNumIncomingValues() == 1) {
595 assert(PN->getNumIncomingValues() == 1);
596 PN->replaceAllUsesWith(PN->getIncomingValue(0));
597 PN->getParent()->getInstList().erase(PN);
598 I = OldSucc->begin();
599 } else if (PN->getNumIncomingValues() == 0) { // Nuke the PHI
600 // If we removed the last incoming value to this PHI, nuke the PHI node
602 PN->replaceAllUsesWith(Constant::getNullValue(PN->getType()));
603 PN->getParent()->getInstList().erase(PN);
604 I = OldSucc->begin();
606 ++I; // Otherwise, move on to the next PHI node
610 // Actually revector the branch now...
611 TI->setSuccessor(SuccNo, Dest);
613 // If we just introduced a critical edge in the flow graph, make sure to break
615 SplitCriticalEdge(TI, SuccNo, this);
617 // Make sure that we don't introduce critical edges from oldsucc now!
618 for (unsigned i = 0, e = OldSucc->getTerminator()->getNumSuccessors();
620 SplitCriticalEdge(OldSucc->getTerminator(), i, this);
622 // Since we invalidated the CFG, recalculate the dominator set so that it is
623 // useful for later processing!
624 // FIXME: This is much worse than it really should be!
627 DOUT << "After forwarding: " << *BB->getParent();
630 /// ReplaceUsesOfValueInRegion - This method replaces all uses of Orig with uses
631 /// of New. It only affects instructions that are defined in basic blocks that
632 /// are dominated by Head.
634 void CEE::ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
635 BasicBlock *RegionDominator) {
636 assert(Orig != New && "Cannot replace value with itself");
637 std::vector<Instruction*> InstsToChange;
638 std::vector<PHINode*> PHIsToChange;
639 InstsToChange.reserve(Orig->getNumUses());
641 // Loop over instructions adding them to InstsToChange vector, this allows us
642 // an easy way to avoid invalidating the use_iterator at a bad time.
643 for (Value::use_iterator I = Orig->use_begin(), E = Orig->use_end();
645 if (Instruction *User = dyn_cast<Instruction>(*I))
646 if (EF->dominates(RegionDominator, User->getParent()))
647 InstsToChange.push_back(User);
648 else if (PHINode *PN = dyn_cast<PHINode>(User)) {
649 PHIsToChange.push_back(PN);
652 // PHIsToChange contains PHI nodes that use Orig that do not live in blocks
653 // dominated by orig. If the block the value flows in from is dominated by
654 // RegionDominator, then we rewrite the PHI
655 for (unsigned i = 0, e = PHIsToChange.size(); i != e; ++i) {
656 PHINode *PN = PHIsToChange[i];
657 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
658 if (PN->getIncomingValue(j) == Orig &&
659 EF->dominates(RegionDominator, PN->getIncomingBlock(j)))
660 PN->setIncomingValue(j, New);
663 // Loop over the InstsToChange list, replacing all uses of Orig with uses of
664 // New. This list contains all of the instructions in our region that use
666 for (unsigned i = 0, e = InstsToChange.size(); i != e; ++i)
667 if (PHINode *PN = dyn_cast<PHINode>(InstsToChange[i])) {
668 // PHINodes must be handled carefully. If the PHI node itself is in the
669 // region, we have to make sure to only do the replacement for incoming
670 // values that correspond to basic blocks in the region.
671 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
672 if (PN->getIncomingValue(j) == Orig &&
673 EF->dominates(RegionDominator, PN->getIncomingBlock(j)))
674 PN->setIncomingValue(j, New);
677 InstsToChange[i]->replaceUsesOfWith(Orig, New);
681 static void CalcRegionExitBlocks(BasicBlock *Header, BasicBlock *BB,
682 std::set<BasicBlock*> &Visited,
684 std::vector<BasicBlock*> &RegionExitBlocks) {
685 if (Visited.count(BB)) return;
688 if (EF.dominates(Header, BB)) { // Block in the region, recursively traverse
689 for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
690 CalcRegionExitBlocks(Header, *I, Visited, EF, RegionExitBlocks);
692 // Header does not dominate this block, but we have a predecessor that does
693 // dominate us. Add ourself to the list.
694 RegionExitBlocks.push_back(BB);
698 /// CalculateRegionExitBlocks - Find all of the blocks that are not dominated by
699 /// BB, but have predecessors that are. Additionally, prune down the set to
700 /// only include blocks that are dominated by OldSucc as well.
702 void CEE::CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
703 std::vector<BasicBlock*> &RegionExitBlocks){
704 std::set<BasicBlock*> Visited; // Don't infinite loop
706 // Recursively calculate blocks we are interested in...
707 CalcRegionExitBlocks(BB, BB, Visited, *EF, RegionExitBlocks);
709 // Filter out blocks that are not dominated by OldSucc...
710 for (unsigned i = 0; i != RegionExitBlocks.size(); ) {
711 if (EF->dominates(OldSucc, RegionExitBlocks[i]))
712 ++i; // Block is ok, keep it.
714 // Move to end of list...
715 std::swap(RegionExitBlocks[i], RegionExitBlocks.back());
716 RegionExitBlocks.pop_back(); // Nuke the end
721 void CEE::InsertRegionExitMerges(PHINode *BBVal, Instruction *OldVal,
722 const std::vector<BasicBlock*> &RegionExitBlocks) {
723 assert(BBVal->getType() == OldVal->getType() && "Should be derived values!");
724 BasicBlock *BB = BBVal->getParent();
726 // Loop over all of the blocks we have to place PHIs in, doing it.
727 for (unsigned i = 0, e = RegionExitBlocks.size(); i != e; ++i) {
728 BasicBlock *FBlock = RegionExitBlocks[i]; // Block on the frontier
730 // Create the new PHI node
731 PHINode *NewPN = new PHINode(BBVal->getType(),
732 OldVal->getName()+".fw_frontier",
735 // Add an incoming value for every predecessor of the block...
736 for (pred_iterator PI = pred_begin(FBlock), PE = pred_end(FBlock);
738 // If the incoming edge is from the region dominated by BB, use BBVal,
739 // otherwise use OldVal.
740 NewPN->addIncoming(EF->dominates(BB, *PI) ? BBVal : OldVal, *PI);
743 // Now make everyone dominated by this block use this new value!
744 ReplaceUsesOfValueInRegion(OldVal, NewPN, FBlock);
750 // BuildRankMap - This method builds the rank map data structure which gives
751 // each instruction/value in the function a value based on how early it appears
752 // in the function. We give constants and globals rank 0, arguments are
753 // numbered starting at one, and instructions are numbered in reverse post-order
754 // from where the arguments leave off. This gives instructions in loops higher
755 // values than instructions not in loops.
757 void CEE::BuildRankMap(Function &F) {
758 unsigned Rank = 1; // Skip rank zero.
760 // Number the arguments...
761 for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
764 // Number the instructions in reverse post order...
765 ReversePostOrderTraversal<Function*> RPOT(&F);
766 for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
767 E = RPOT.end(); I != E; ++I)
768 for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end();
770 if (BBI->getType() != Type::VoidTy)
771 RankMap[BBI] = Rank++;
775 // PropagateBranchInfo - When this method is invoked, we need to propagate
776 // information derived from the branch condition into the true and false
777 // branches of BI. Since we know that there aren't any critical edges in the
778 // flow graph, this can proceed unconditionally.
780 void CEE::PropagateBranchInfo(BranchInst *BI) {
781 assert(BI->isConditional() && "Must be a conditional branch!");
783 // Propagate information into the true block...
785 PropagateEquality(BI->getCondition(), ConstantBool::getTrue(),
786 getRegionInfo(BI->getSuccessor(0)));
788 // Propagate information into the false block...
790 PropagateEquality(BI->getCondition(), ConstantBool::getFalse(),
791 getRegionInfo(BI->getSuccessor(1)));
795 // PropagateSwitchInfo - We need to propagate the value tested by the
796 // switch statement through each case block.
798 void CEE::PropagateSwitchInfo(SwitchInst *SI) {
799 // Propagate information down each of our non-default case labels. We
800 // don't yet propagate information down the default label, because a
801 // potentially large number of inequality constraints provide less
802 // benefit per unit work than a single equality constraint.
804 Value *cond = SI->getCondition();
805 for (unsigned i = 1; i < SI->getNumSuccessors(); ++i)
806 PropagateEquality(cond, SI->getSuccessorValue(i),
807 getRegionInfo(SI->getSuccessor(i)));
811 // PropagateEquality - If we discover that two values are equal to each other in
812 // a specified region, propagate this knowledge recursively.
814 void CEE::PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI) {
815 if (Op0 == Op1) return; // Gee whiz. Are these really equal each other?
817 if (isa<Constant>(Op0)) // Make sure the constant is always Op1
820 // Make sure we don't already know these are equal, to avoid infinite loops...
821 ValueInfo &VI = RI.getValueInfo(Op0);
823 // Get information about the known relationship between Op0 & Op1
824 Relation &KnownRelation = VI.getRelation(Op1);
826 // If we already know they're equal, don't reprocess...
827 if (KnownRelation.getRelation() == FCmpInst::FCMP_OEQ ||
828 KnownRelation.getRelation() == ICmpInst::ICMP_EQ)
831 // If this is boolean, check to see if one of the operands is a constant. If
832 // it's a constant, then see if the other one is one of a setcc instruction,
833 // an AND, OR, or XOR instruction.
835 if (ConstantBool *CB = dyn_cast<ConstantBool>(Op1)) {
837 if (Instruction *Inst = dyn_cast<Instruction>(Op0)) {
838 // If we know that this instruction is an AND instruction, and the result
839 // is true, this means that both operands to the OR are known to be true
842 if (CB->getValue() && Inst->getOpcode() == Instruction::And) {
843 PropagateEquality(Inst->getOperand(0), CB, RI);
844 PropagateEquality(Inst->getOperand(1), CB, RI);
847 // If we know that this instruction is an OR instruction, and the result
848 // is false, this means that both operands to the OR are know to be false
851 if (!CB->getValue() && Inst->getOpcode() == Instruction::Or) {
852 PropagateEquality(Inst->getOperand(0), CB, RI);
853 PropagateEquality(Inst->getOperand(1), CB, RI);
856 // If we know that this instruction is a NOT instruction, we know that the
857 // operand is known to be the inverse of whatever the current value is.
859 if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(Inst))
860 if (BinaryOperator::isNot(BOp))
861 PropagateEquality(BinaryOperator::getNotArgument(BOp),
862 ConstantBool::get(!CB->getValue()), RI);
864 // If we know the value of a FCmp instruction, propagate the information
865 // about the relation into this region as well.
867 if (FCmpInst *FCI = dyn_cast<FCmpInst>(Inst)) {
868 if (CB->getValue()) { // If we know the condition is true...
869 // Propagate info about the LHS to the RHS & RHS to LHS
870 PropagateRelation(FCI->getPredicate(), FCI->getOperand(0),
871 FCI->getOperand(1), RI);
872 PropagateRelation(FCI->getSwappedPredicate(),
873 FCI->getOperand(1), FCI->getOperand(0), RI);
875 } else { // If we know the condition is false...
876 // We know the opposite of the condition is true...
877 FCmpInst::Predicate C = FCI->getInversePredicate();
879 PropagateRelation(C, FCI->getOperand(0), FCI->getOperand(1), RI);
880 PropagateRelation(FCmpInst::getSwappedPredicate(C),
881 FCI->getOperand(1), FCI->getOperand(0), RI);
885 // If we know the value of a ICmp instruction, propagate the information
886 // about the relation into this region as well.
888 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Inst)) {
889 if (CB->getValue()) { // If we know the condition is true...
890 // Propagate info about the LHS to the RHS & RHS to LHS
891 PropagateRelation(ICI->getPredicate(), ICI->getOperand(0),
892 ICI->getOperand(1), RI);
893 PropagateRelation(ICI->getSwappedPredicate(), ICI->getOperand(1),
894 ICI->getOperand(1), RI);
896 } else { // If we know the condition is false ...
897 // We know the opposite of the condition is true...
898 ICmpInst::Predicate C = ICI->getInversePredicate();
900 PropagateRelation(C, ICI->getOperand(0), ICI->getOperand(1), RI);
901 PropagateRelation(ICmpInst::getSwappedPredicate(C),
902 ICI->getOperand(1), ICI->getOperand(0), RI);
908 // Propagate information about Op0 to Op1 & visa versa
909 PropagateRelation(ICmpInst::ICMP_EQ, Op0, Op1, RI);
910 PropagateRelation(ICmpInst::ICMP_EQ, Op1, Op0, RI);
911 PropagateRelation(FCmpInst::FCMP_OEQ, Op0, Op1, RI);
912 PropagateRelation(FCmpInst::FCMP_OEQ, Op1, Op0, RI);
916 // PropagateRelation - We know that the specified relation is true in all of the
917 // blocks in the specified region. Propagate the information about Op0 and
918 // anything derived from it into this region.
920 void CEE::PropagateRelation(unsigned Opcode, Value *Op0,
921 Value *Op1, RegionInfo &RI) {
922 assert(Op0->getType() == Op1->getType() && "Equal types expected!");
924 // Constants are already pretty well understood. We will apply information
925 // about the constant to Op1 in another call to PropagateRelation.
927 if (isa<Constant>(Op0)) return;
929 // Get the region information for this block to update...
930 ValueInfo &VI = RI.getValueInfo(Op0);
932 // Get information about the known relationship between Op0 & Op1
933 Relation &Op1R = VI.getRelation(Op1);
935 // Quick bailout for common case if we are reprocessing an instruction...
936 if (Op1R.getRelation() == Opcode)
939 // If we already have information that contradicts the current information we
940 // are propagating, ignore this info. Something bad must have happened!
942 if (Op1R.contradicts(Opcode, VI)) {
943 Op1R.contradicts(Opcode, VI);
944 cerr << "Contradiction found for opcode: "
945 << ((isa<ICmpInst>(Op0)||isa<ICmpInst>(Op1)) ?
946 Instruction::getOpcodeName(Instruction::ICmp) :
947 Instruction::getOpcodeName(Opcode))
949 Op1R.print(*cerr.stream());
953 // If the information propagated is new, then we want process the uses of this
954 // instruction to propagate the information down to them.
956 if (Op1R.incorporate(Opcode, VI))
957 UpdateUsersOfValue(Op0, RI);
961 // UpdateUsersOfValue - The information about V in this region has been updated.
962 // Propagate this to all consumers of the value.
964 void CEE::UpdateUsersOfValue(Value *V, RegionInfo &RI) {
965 for (Value::use_iterator I = V->use_begin(), E = V->use_end();
967 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
968 // If this is an instruction using a value that we know something about,
969 // try to propagate information to the value produced by the
970 // instruction. We can only do this if it is an instruction we can
971 // propagate information for (a setcc for example), and we only WANT to
972 // do this if the instruction dominates this region.
974 // If the instruction doesn't dominate this region, then it cannot be
975 // used in this region and we don't care about it. If the instruction
976 // is IN this region, then we will simplify the instruction before we
977 // get to uses of it anyway, so there is no reason to bother with it
978 // here. This check is also effectively checking to make sure that Inst
979 // is in the same function as our region (in case V is a global f.e.).
981 if (EF->properlyDominates(Inst->getParent(), RI.getEntryBlock()))
982 IncorporateInstruction(Inst, RI);
986 // IncorporateInstruction - We just updated the information about one of the
987 // operands to the specified instruction. Update the information about the
988 // value produced by this instruction
990 void CEE::IncorporateInstruction(Instruction *Inst, RegionInfo &RI) {
991 if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) {
992 // See if we can figure out a result for this instruction...
993 Relation::KnownResult Result = getCmpResult(CI, RI);
994 if (Result != Relation::Unknown) {
995 PropagateEquality(CI, ConstantBool::get(Result != 0), RI);
1001 // ComputeReplacements - Some values are known to be equal to other values in a
1002 // region. For example if there is a comparison of equality between a variable
1003 // X and a constant C, we can replace all uses of X with C in the region we are
1004 // interested in. We generalize this replacement to replace variables with
1005 // other variables if they are equal and there is a variable with lower rank
1006 // than the current one. This offers a canonicalizing property that exposes
1007 // more redundancies for later transformations to take advantage of.
1009 void CEE::ComputeReplacements(RegionInfo &RI) {
1010 // Loop over all of the values in the region info map...
1011 for (RegionInfo::iterator I = RI.begin(), E = RI.end(); I != E; ++I) {
1012 ValueInfo &VI = I->second;
1014 // If we know that this value is a particular constant, set Replacement to
1016 Value *Replacement = VI.getBounds().getSingleElement();
1018 // If this value is not known to be some constant, figure out the lowest
1019 // rank value that it is known to be equal to (if anything).
1021 if (Replacement == 0) {
1022 // Find out if there are any equality relationships with values of lower
1023 // rank than VI itself...
1024 unsigned MinRank = getRank(I->first);
1026 // Loop over the relationships known about Op0.
1027 const std::vector<Relation> &Relationships = VI.getRelationships();
1028 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
1029 if (Relationships[i].getRelation() == FCmpInst::FCMP_OEQ) {
1030 unsigned R = getRank(Relationships[i].getValue());
1033 Replacement = Relationships[i].getValue();
1036 else if (Relationships[i].getRelation() == ICmpInst::ICMP_EQ) {
1037 unsigned R = getRank(Relationships[i].getValue());
1040 Replacement = Relationships[i].getValue();
1045 // If we found something to replace this value with, keep track of it.
1047 VI.setReplacement(Replacement);
1051 // SimplifyBasicBlock - Given information about values in region RI, simplify
1052 // the instructions in the specified basic block.
1054 bool CEE::SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI) {
1055 bool Changed = false;
1056 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ) {
1057 Instruction *Inst = I++;
1059 // Convert instruction arguments to canonical forms...
1060 Changed |= SimplifyInstruction(Inst, RI);
1062 if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) {
1063 // Try to simplify a setcc instruction based on inherited information
1064 Relation::KnownResult Result = getCmpResult(CI, RI);
1065 if (Result != Relation::Unknown) {
1066 DEBUG(cerr << "Replacing icmp with " << Result
1067 << " constant: " << *CI);
1069 CI->replaceAllUsesWith(ConstantBool::get((bool)Result));
1070 // The instruction is now dead, remove it from the program.
1071 CI->getParent()->getInstList().erase(CI);
1081 // SimplifyInstruction - Inspect the operands of the instruction, converting
1082 // them to their canonical form if possible. This takes care of, for example,
1083 // replacing a value 'X' with a constant 'C' if the instruction in question is
1084 // dominated by a true seteq 'X', 'C'.
1086 bool CEE::SimplifyInstruction(Instruction *I, const RegionInfo &RI) {
1087 bool Changed = false;
1089 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1090 if (const ValueInfo *VI = RI.requestValueInfo(I->getOperand(i)))
1091 if (Value *Repl = VI->getReplacement()) {
1092 // If we know if a replacement with lower rank than Op0, make the
1094 DOUT << "In Inst: " << *I << " Replacing operand #" << i
1095 << " with " << *Repl << "\n";
1096 I->setOperand(i, Repl);
1104 // getCmpResult - Try to simplify a cmp instruction based on information
1105 // inherited from a dominating icmp instruction. V is one of the operands to
1106 // the icmp instruction, and VI is the set of information known about it. We
1107 // take two cases into consideration here. If the comparison is against a
1108 // constant value, we can use the constant range to see if the comparison is
1109 // possible to succeed. If it is not a comparison against a constant, we check
1110 // to see if there is a known relationship between the two values. If so, we
1111 // may be able to eliminate the check.
1113 Relation::KnownResult CEE::getCmpResult(CmpInst *CI,
1114 const RegionInfo &RI) {
1115 Value *Op0 = CI->getOperand(0), *Op1 = CI->getOperand(1);
1116 unsigned short predicate = CI->getPredicate();
1118 if (isa<Constant>(Op0)) {
1119 if (isa<Constant>(Op1)) {
1120 if (Constant *Result = ConstantFoldInstruction(CI)) {
1121 // Wow, this is easy, directly eliminate the ICmpInst.
1122 DEBUG(cerr << "Replacing cmp with constant fold: " << *CI);
1123 return cast<ConstantBool>(Result)->getValue()
1124 ? Relation::KnownTrue : Relation::KnownFalse;
1127 // We want to swap this instruction so that operand #0 is the constant.
1128 std::swap(Op0, Op1);
1129 if (isa<ICmpInst>(CI))
1130 predicate = cast<ICmpInst>(CI)->getSwappedPredicate();
1132 predicate = cast<FCmpInst>(CI)->getSwappedPredicate();
1136 // Try to figure out what the result of this comparison will be...
1137 Relation::KnownResult Result = Relation::Unknown;
1139 // We have to know something about the relationship to prove anything...
1140 if (const ValueInfo *Op0VI = RI.requestValueInfo(Op0)) {
1142 // At this point, we know that if we have a constant argument that it is in
1143 // Op1. Check to see if we know anything about comparing value with a
1144 // constant, and if we can use this info to fold the icmp.
1146 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(Op1)) {
1147 // Check to see if we already know the result of this comparison...
1148 ConstantRange R = ConstantRange(predicate, C);
1149 ConstantRange Int = R.intersectWith(Op0VI->getBounds(),
1150 ICmpInst::isSignedPredicate(ICmpInst::Predicate(predicate)));
1152 // If the intersection of the two ranges is empty, then the condition
1153 // could never be true!
1155 if (Int.isEmptySet()) {
1156 Result = Relation::KnownFalse;
1158 // Otherwise, if VI.getBounds() (the possible values) is a subset of R
1159 // (the allowed values) then we know that the condition must always be
1162 } else if (Int == Op0VI->getBounds()) {
1163 Result = Relation::KnownTrue;
1166 // If we are here, we know that the second argument is not a constant
1167 // integral. See if we know anything about Op0 & Op1 that allows us to
1168 // fold this anyway.
1170 // Do we have value information about Op0 and a relation to Op1?
1171 if (const Relation *Op2R = Op0VI->requestRelation(Op1))
1172 Result = Op2R->getImpliedResult(predicate);
1178 //===----------------------------------------------------------------------===//
1179 // Relation Implementation
1180 //===----------------------------------------------------------------------===//
1182 // contradicts - Return true if the relationship specified by the operand
1183 // contradicts already known information.
1185 bool Relation::contradicts(unsigned Op,
1186 const ValueInfo &VI) const {
1187 assert (Op != Instruction::Add && "Invalid relation argument!");
1189 // If this is a relationship with a constant, make sure that this relationship
1190 // does not contradict properties known about the bounds of the constant.
1192 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(Val))
1193 if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
1194 Op <= ICmpInst::LAST_ICMP_PREDICATE)
1195 if (ConstantRange(Op, C).intersectWith(VI.getBounds(),
1196 ICmpInst::isSignedPredicate(ICmpInst::Predicate(Op))).isEmptySet())
1200 default: assert(0 && "Unknown Relationship code!");
1201 case Instruction::Add: return false; // Nothing known, nothing contradicts
1202 case ICmpInst::ICMP_EQ:
1203 return Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_SLT ||
1204 Op == ICmpInst::ICMP_UGT || Op == ICmpInst::ICMP_SGT ||
1205 Op == ICmpInst::ICMP_NE;
1206 case ICmpInst::ICMP_NE: return Op == ICmpInst::ICMP_EQ;
1207 case ICmpInst::ICMP_ULE:
1208 case ICmpInst::ICMP_SLE: return Op == ICmpInst::ICMP_UGT ||
1209 Op == ICmpInst::ICMP_SGT;
1210 case ICmpInst::ICMP_UGE:
1211 case ICmpInst::ICMP_SGE: return Op == ICmpInst::ICMP_ULT ||
1212 Op == ICmpInst::ICMP_SLT;
1213 case ICmpInst::ICMP_ULT:
1214 case ICmpInst::ICMP_SLT:
1215 return Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_UGT ||
1216 Op == ICmpInst::ICMP_SGT || Op == ICmpInst::ICMP_UGE ||
1217 Op == ICmpInst::ICMP_SGE;
1218 case ICmpInst::ICMP_UGT:
1219 case ICmpInst::ICMP_SGT:
1220 return Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_ULT ||
1221 Op == ICmpInst::ICMP_SLT || Op == ICmpInst::ICMP_ULE ||
1222 Op == ICmpInst::ICMP_SLE;
1223 case FCmpInst::FCMP_OEQ:
1224 return Op == FCmpInst::FCMP_OLT || Op == FCmpInst::FCMP_OGT ||
1225 Op == FCmpInst::FCMP_ONE;
1226 case FCmpInst::FCMP_ONE: return Op == FCmpInst::FCMP_OEQ;
1227 case FCmpInst::FCMP_OLE: return Op == FCmpInst::FCMP_OGT;
1228 case FCmpInst::FCMP_OGE: return Op == FCmpInst::FCMP_OLT;
1229 case FCmpInst::FCMP_OLT:
1230 return Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OGT ||
1231 Op == FCmpInst::FCMP_OGE;
1232 case FCmpInst::FCMP_OGT:
1233 return Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OLT ||
1234 Op == FCmpInst::FCMP_OLE;
1238 // incorporate - Incorporate information in the argument into this relation
1239 // entry. This assumes that the information doesn't contradict itself. If any
1240 // new information is gained, true is returned, otherwise false is returned to
1241 // indicate that nothing was updated.
1243 bool Relation::incorporate(unsigned Op, ValueInfo &VI) {
1244 assert(!contradicts(Op, VI) &&
1245 "Cannot incorporate contradictory information!");
1247 // If this is a relationship with a constant, make sure that we update the
1248 // range that is possible for the value to have...
1250 if (ConstantIntegral *C = dyn_cast<ConstantIntegral>(Val))
1251 if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
1252 Op <= ICmpInst::LAST_ICMP_PREDICATE)
1253 VI.getBounds() = ConstantRange(Op, C).intersectWith(VI.getBounds(),
1254 ICmpInst::isSignedPredicate(ICmpInst::Predicate(Op)));
1257 default: assert(0 && "Unknown prior value!");
1258 case Instruction::Add: Rel = Op; return true;
1259 case ICmpInst::ICMP_EQ:
1260 case ICmpInst::ICMP_NE:
1261 case ICmpInst::ICMP_ULT:
1262 case ICmpInst::ICMP_SLT:
1263 case ICmpInst::ICMP_UGT:
1264 case ICmpInst::ICMP_SGT: return false; // Nothing is more precise
1265 case ICmpInst::ICMP_ULE:
1266 case ICmpInst::ICMP_SLE:
1267 if (Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_ULT ||
1268 Op == ICmpInst::ICMP_SLT) {
1271 } else if (Op == ICmpInst::ICMP_NE) {
1272 Rel = Rel == ICmpInst::ICMP_ULE ? ICmpInst::ICMP_ULT :
1277 case ICmpInst::ICMP_UGE:
1278 case ICmpInst::ICMP_SGE:
1279 if (Op == ICmpInst::ICMP_EQ || ICmpInst::ICMP_UGT ||
1280 Op == ICmpInst::ICMP_SGT) {
1283 } else if (Op == ICmpInst::ICMP_NE) {
1284 Rel = Rel == ICmpInst::ICMP_UGE ? ICmpInst::ICMP_UGT :
1289 case FCmpInst::FCMP_OEQ: return false; // Nothing is more precise
1290 case FCmpInst::FCMP_ONE: return false; // Nothing is more precise
1291 case FCmpInst::FCMP_OLT: return false; // Nothing is more precise
1292 case FCmpInst::FCMP_OGT: return false; // Nothing is more precise
1293 case FCmpInst::FCMP_OLE:
1294 if (Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OLT) {
1297 } else if (Op == FCmpInst::FCMP_ONE) {
1298 Rel = FCmpInst::FCMP_OLT;
1302 case FCmpInst::FCMP_OGE:
1303 return Op == FCmpInst::FCMP_OLT;
1304 if (Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OGT) {
1307 } else if (Op == FCmpInst::FCMP_ONE) {
1308 Rel = FCmpInst::FCMP_OGT;
1315 // getImpliedResult - If this relationship between two values implies that
1316 // the specified relationship is true or false, return that. If we cannot
1317 // determine the result required, return Unknown.
1319 Relation::KnownResult
1320 Relation::getImpliedResult(unsigned Op) const {
1321 if (Rel == Op) return KnownTrue;
1322 if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
1323 Op <= ICmpInst::LAST_ICMP_PREDICATE) {
1324 if (Rel == unsigned(ICmpInst::getInversePredicate(ICmpInst::Predicate(Op))))
1326 } else if (Op <= FCmpInst::LAST_FCMP_PREDICATE) {
1327 if (Rel == unsigned(FCmpInst::getInversePredicate(FCmpInst::Predicate(Op))))
1332 default: assert(0 && "Unknown prior value!");
1333 case ICmpInst::ICMP_EQ:
1334 if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_SLE ||
1335 Op == ICmpInst::ICMP_UGE || Op == ICmpInst::ICMP_SGE) return KnownTrue;
1336 if (Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_SLT ||
1337 Op == ICmpInst::ICMP_UGT || Op == ICmpInst::ICMP_SGT) return KnownFalse;
1339 case ICmpInst::ICMP_ULT:
1340 case ICmpInst::ICMP_SLT:
1341 if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_SLE ||
1342 Op == ICmpInst::ICMP_NE) return KnownTrue;
1343 if (Op == ICmpInst::ICMP_EQ) return KnownFalse;
1345 case ICmpInst::ICMP_UGT:
1346 case ICmpInst::ICMP_SGT:
1347 if (Op == ICmpInst::ICMP_UGE || Op == ICmpInst::ICMP_SGE ||
1348 Op == ICmpInst::ICMP_NE) return KnownTrue;
1349 if (Op == ICmpInst::ICMP_EQ) return KnownFalse;
1351 case FCmpInst::FCMP_OEQ:
1352 if (Op == FCmpInst::FCMP_OLE || Op == FCmpInst::FCMP_OGE) return KnownTrue;
1353 if (Op == FCmpInst::FCMP_OLT || Op == FCmpInst::FCMP_OGT) return KnownFalse;
1355 case FCmpInst::FCMP_OLT:
1356 if (Op == FCmpInst::FCMP_ONE || Op == FCmpInst::FCMP_OLE) return KnownTrue;
1357 if (Op == FCmpInst::FCMP_OEQ) return KnownFalse;
1359 case FCmpInst::FCMP_OGT:
1360 if (Op == FCmpInst::FCMP_ONE || Op == FCmpInst::FCMP_OGE) return KnownTrue;
1361 if (Op == FCmpInst::FCMP_OEQ) return KnownFalse;
1363 case ICmpInst::ICMP_NE:
1364 case ICmpInst::ICMP_SLE:
1365 case ICmpInst::ICMP_ULE:
1366 case ICmpInst::ICMP_UGE:
1367 case ICmpInst::ICMP_SGE:
1368 case FCmpInst::FCMP_ONE:
1369 case FCmpInst::FCMP_OLE:
1370 case FCmpInst::FCMP_OGE:
1371 case FCmpInst::FCMP_FALSE:
1372 case FCmpInst::FCMP_ORD:
1373 case FCmpInst::FCMP_UNO:
1374 case FCmpInst::FCMP_UEQ:
1375 case FCmpInst::FCMP_UGT:
1376 case FCmpInst::FCMP_UGE:
1377 case FCmpInst::FCMP_ULT:
1378 case FCmpInst::FCMP_ULE:
1379 case FCmpInst::FCMP_UNE:
1380 case FCmpInst::FCMP_TRUE:
1387 //===----------------------------------------------------------------------===//
1388 // Printing Support...
1389 //===----------------------------------------------------------------------===//
1391 // print - Implement the standard print form to print out analysis information.
1392 void CEE::print(std::ostream &O, const Module *M) const {
1393 O << "\nPrinting Correlated Expression Info:\n";
1394 for (std::map<BasicBlock*, RegionInfo>::const_iterator I =
1395 RegionInfoMap.begin(), E = RegionInfoMap.end(); I != E; ++I)
1399 // print - Output information about this region...
1400 void RegionInfo::print(std::ostream &OS) const {
1401 if (ValueMap.empty()) return;
1403 OS << " RegionInfo for basic block: " << BB->getName() << "\n";
1404 for (std::map<Value*, ValueInfo>::const_iterator
1405 I = ValueMap.begin(), E = ValueMap.end(); I != E; ++I)
1406 I->second.print(OS, I->first);
1410 // print - Output information about this value relation...
1411 void ValueInfo::print(std::ostream &OS, Value *V) const {
1412 if (Relationships.empty()) return;
1415 OS << " ValueInfo for: ";
1416 WriteAsOperand(OS, V);
1418 OS << "\n Bounds = " << Bounds << "\n";
1420 OS << " Replacement = ";
1421 WriteAsOperand(OS, Replacement);
1424 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
1425 Relationships[i].print(OS);
1428 // print - Output this relation to the specified stream
1429 void Relation::print(std::ostream &OS) const {
1432 default: OS << "*UNKNOWN*"; break;
1433 case ICmpInst::ICMP_EQ:
1434 case FCmpInst::FCMP_ORD:
1435 case FCmpInst::FCMP_UEQ:
1436 case FCmpInst::FCMP_OEQ: OS << "== "; break;
1437 case ICmpInst::ICMP_NE:
1438 case FCmpInst::FCMP_UNO:
1439 case FCmpInst::FCMP_UNE:
1440 case FCmpInst::FCMP_ONE: OS << "!= "; break;
1441 case ICmpInst::ICMP_ULT:
1442 case ICmpInst::ICMP_SLT:
1443 case FCmpInst::FCMP_ULT:
1444 case FCmpInst::FCMP_OLT: OS << "< "; break;
1445 case ICmpInst::ICMP_UGT:
1446 case ICmpInst::ICMP_SGT:
1447 case FCmpInst::FCMP_UGT:
1448 case FCmpInst::FCMP_OGT: OS << "> "; break;
1449 case ICmpInst::ICMP_ULE:
1450 case ICmpInst::ICMP_SLE:
1451 case FCmpInst::FCMP_ULE:
1452 case FCmpInst::FCMP_OLE: OS << "<= "; break;
1453 case ICmpInst::ICMP_UGE:
1454 case ICmpInst::ICMP_SGE:
1455 case FCmpInst::FCMP_UGE:
1456 case FCmpInst::FCMP_OGE: OS << ">= "; break;
1459 WriteAsOperand(OS, Val);
1463 // Don't inline these methods or else we won't be able to call them from GDB!
1464 void Relation::dump() const { print(*cerr.stream()); }
1465 void ValueInfo::dump() const { print(*cerr.stream(), 0); }
1466 void RegionInfo::dump() const { print(*cerr.stream()); }