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, ConstantInt::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 ConstantInt *CB = cast<ConstantInt>(PredicateVI.getReplacement());
489 // Forward to the successor that corresponds to the branch we will take.
490 ForwardSuccessorTo(TI, SuccNo,
491 BI->getSuccessor(!CB->getBoolValue()), NewRI);
498 static Value *getReplacementOrValue(Value *V, RegionInfo &RI) {
499 if (const ValueInfo *VI = RI.requestValueInfo(V))
500 if (Value *Repl = VI->getReplacement())
505 /// ForwardSuccessorTo - We have found that we can forward successor # 'SuccNo'
506 /// of Terminator 'TI' to the 'Dest' BasicBlock. This method performs the
507 /// mechanics of updating SSA information and revectoring the branch.
509 void CEE::ForwardSuccessorTo(TerminatorInst *TI, unsigned SuccNo,
510 BasicBlock *Dest, RegionInfo &RI) {
511 // If there are any PHI nodes in the Dest BB, we must duplicate the entry
512 // in the PHI node for the old successor to now include an entry from the
513 // current basic block.
515 BasicBlock *OldSucc = TI->getSuccessor(SuccNo);
516 BasicBlock *BB = TI->getParent();
518 DOUT << "Forwarding branch in basic block %" << BB->getName()
519 << " from block %" << OldSucc->getName() << " to block %"
520 << Dest->getName() << "\n"
521 << "Before forwarding: " << *BB->getParent();
523 // Because we know that there cannot be critical edges in the flow graph, and
524 // that OldSucc has multiple outgoing edges, this means that Dest cannot have
525 // multiple incoming edges.
528 pred_iterator DPI = pred_begin(Dest); ++DPI;
529 assert(DPI == pred_end(Dest) && "Critical edge found!!");
532 // Loop over any PHI nodes in the destination, eliminating them, because they
533 // may only have one input.
535 while (PHINode *PN = dyn_cast<PHINode>(&Dest->front())) {
536 assert(PN->getNumIncomingValues() == 1 && "Crit edge found!");
537 // Eliminate the PHI node
538 PN->replaceAllUsesWith(PN->getIncomingValue(0));
539 Dest->getInstList().erase(PN);
542 // If there are values defined in the "OldSucc" basic block, we need to insert
543 // PHI nodes in the regions we are dealing with to emulate them. This can
544 // insert dead phi nodes, but it is more trouble to see if they are used than
545 // to just blindly insert them.
547 if (EF->dominates(OldSucc, Dest)) {
548 // RegionExitBlocks - Find all of the blocks that are not dominated by Dest,
549 // but have predecessors that are. Additionally, prune down the set to only
550 // include blocks that are dominated by OldSucc as well.
552 std::vector<BasicBlock*> RegionExitBlocks;
553 CalculateRegionExitBlocks(Dest, OldSucc, RegionExitBlocks);
555 for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end();
557 if (I->getType() != Type::VoidTy) {
558 // Create and insert the PHI node into the top of Dest.
559 PHINode *NewPN = new PHINode(I->getType(), I->getName()+".fw_merge",
561 // There is definitely an edge from OldSucc... add the edge now
562 NewPN->addIncoming(I, OldSucc);
564 // There is also an edge from BB now, add the edge with the calculated
565 // value from the RI.
566 NewPN->addIncoming(getReplacementOrValue(I, RI), BB);
568 // Make everything in the Dest region use the new PHI node now...
569 ReplaceUsesOfValueInRegion(I, NewPN, Dest);
571 // Make sure that exits out of the region dominated by NewPN get PHI
572 // nodes that merge the values as appropriate.
573 InsertRegionExitMerges(NewPN, I, RegionExitBlocks);
577 // If there were PHI nodes in OldSucc, we need to remove the entry for this
578 // edge from the PHI node, and we need to replace any references to the PHI
579 // node with a new value.
581 for (BasicBlock::iterator I = OldSucc->begin(); isa<PHINode>(I); ) {
582 PHINode *PN = cast<PHINode>(I);
584 // Get the value flowing across the old edge and remove the PHI node entry
585 // for this edge: we are about to remove the edge! Don't remove the PHI
586 // node yet though if this is the last edge into it.
587 Value *EdgeValue = PN->removeIncomingValue(BB, false);
589 // Make sure that anything that used to use PN now refers to EdgeValue
590 ReplaceUsesOfValueInRegion(PN, EdgeValue, Dest);
592 // If there is only one value left coming into the PHI node, replace the PHI
593 // node itself with the one incoming value left.
595 if (PN->getNumIncomingValues() == 1) {
596 assert(PN->getNumIncomingValues() == 1);
597 PN->replaceAllUsesWith(PN->getIncomingValue(0));
598 PN->getParent()->getInstList().erase(PN);
599 I = OldSucc->begin();
600 } else if (PN->getNumIncomingValues() == 0) { // Nuke the PHI
601 // If we removed the last incoming value to this PHI, nuke the PHI node
603 PN->replaceAllUsesWith(Constant::getNullValue(PN->getType()));
604 PN->getParent()->getInstList().erase(PN);
605 I = OldSucc->begin();
607 ++I; // Otherwise, move on to the next PHI node
611 // Actually revector the branch now...
612 TI->setSuccessor(SuccNo, Dest);
614 // If we just introduced a critical edge in the flow graph, make sure to break
616 SplitCriticalEdge(TI, SuccNo, this);
618 // Make sure that we don't introduce critical edges from oldsucc now!
619 for (unsigned i = 0, e = OldSucc->getTerminator()->getNumSuccessors();
621 SplitCriticalEdge(OldSucc->getTerminator(), i, this);
623 // Since we invalidated the CFG, recalculate the dominator set so that it is
624 // useful for later processing!
625 // FIXME: This is much worse than it really should be!
628 DOUT << "After forwarding: " << *BB->getParent();
631 /// ReplaceUsesOfValueInRegion - This method replaces all uses of Orig with uses
632 /// of New. It only affects instructions that are defined in basic blocks that
633 /// are dominated by Head.
635 void CEE::ReplaceUsesOfValueInRegion(Value *Orig, Value *New,
636 BasicBlock *RegionDominator) {
637 assert(Orig != New && "Cannot replace value with itself");
638 std::vector<Instruction*> InstsToChange;
639 std::vector<PHINode*> PHIsToChange;
640 InstsToChange.reserve(Orig->getNumUses());
642 // Loop over instructions adding them to InstsToChange vector, this allows us
643 // an easy way to avoid invalidating the use_iterator at a bad time.
644 for (Value::use_iterator I = Orig->use_begin(), E = Orig->use_end();
646 if (Instruction *User = dyn_cast<Instruction>(*I))
647 if (EF->dominates(RegionDominator, User->getParent()))
648 InstsToChange.push_back(User);
649 else if (PHINode *PN = dyn_cast<PHINode>(User)) {
650 PHIsToChange.push_back(PN);
653 // PHIsToChange contains PHI nodes that use Orig that do not live in blocks
654 // dominated by orig. If the block the value flows in from is dominated by
655 // RegionDominator, then we rewrite the PHI
656 for (unsigned i = 0, e = PHIsToChange.size(); i != e; ++i) {
657 PHINode *PN = PHIsToChange[i];
658 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
659 if (PN->getIncomingValue(j) == Orig &&
660 EF->dominates(RegionDominator, PN->getIncomingBlock(j)))
661 PN->setIncomingValue(j, New);
664 // Loop over the InstsToChange list, replacing all uses of Orig with uses of
665 // New. This list contains all of the instructions in our region that use
667 for (unsigned i = 0, e = InstsToChange.size(); i != e; ++i)
668 if (PHINode *PN = dyn_cast<PHINode>(InstsToChange[i])) {
669 // PHINodes must be handled carefully. If the PHI node itself is in the
670 // region, we have to make sure to only do the replacement for incoming
671 // values that correspond to basic blocks in the region.
672 for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j)
673 if (PN->getIncomingValue(j) == Orig &&
674 EF->dominates(RegionDominator, PN->getIncomingBlock(j)))
675 PN->setIncomingValue(j, New);
678 InstsToChange[i]->replaceUsesOfWith(Orig, New);
682 static void CalcRegionExitBlocks(BasicBlock *Header, BasicBlock *BB,
683 std::set<BasicBlock*> &Visited,
685 std::vector<BasicBlock*> &RegionExitBlocks) {
686 if (Visited.count(BB)) return;
689 if (EF.dominates(Header, BB)) { // Block in the region, recursively traverse
690 for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I)
691 CalcRegionExitBlocks(Header, *I, Visited, EF, RegionExitBlocks);
693 // Header does not dominate this block, but we have a predecessor that does
694 // dominate us. Add ourself to the list.
695 RegionExitBlocks.push_back(BB);
699 /// CalculateRegionExitBlocks - Find all of the blocks that are not dominated by
700 /// BB, but have predecessors that are. Additionally, prune down the set to
701 /// only include blocks that are dominated by OldSucc as well.
703 void CEE::CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc,
704 std::vector<BasicBlock*> &RegionExitBlocks){
705 std::set<BasicBlock*> Visited; // Don't infinite loop
707 // Recursively calculate blocks we are interested in...
708 CalcRegionExitBlocks(BB, BB, Visited, *EF, RegionExitBlocks);
710 // Filter out blocks that are not dominated by OldSucc...
711 for (unsigned i = 0; i != RegionExitBlocks.size(); ) {
712 if (EF->dominates(OldSucc, RegionExitBlocks[i]))
713 ++i; // Block is ok, keep it.
715 // Move to end of list...
716 std::swap(RegionExitBlocks[i], RegionExitBlocks.back());
717 RegionExitBlocks.pop_back(); // Nuke the end
722 void CEE::InsertRegionExitMerges(PHINode *BBVal, Instruction *OldVal,
723 const std::vector<BasicBlock*> &RegionExitBlocks) {
724 assert(BBVal->getType() == OldVal->getType() && "Should be derived values!");
725 BasicBlock *BB = BBVal->getParent();
727 // Loop over all of the blocks we have to place PHIs in, doing it.
728 for (unsigned i = 0, e = RegionExitBlocks.size(); i != e; ++i) {
729 BasicBlock *FBlock = RegionExitBlocks[i]; // Block on the frontier
731 // Create the new PHI node
732 PHINode *NewPN = new PHINode(BBVal->getType(),
733 OldVal->getName()+".fw_frontier",
736 // Add an incoming value for every predecessor of the block...
737 for (pred_iterator PI = pred_begin(FBlock), PE = pred_end(FBlock);
739 // If the incoming edge is from the region dominated by BB, use BBVal,
740 // otherwise use OldVal.
741 NewPN->addIncoming(EF->dominates(BB, *PI) ? BBVal : OldVal, *PI);
744 // Now make everyone dominated by this block use this new value!
745 ReplaceUsesOfValueInRegion(OldVal, NewPN, FBlock);
751 // BuildRankMap - This method builds the rank map data structure which gives
752 // each instruction/value in the function a value based on how early it appears
753 // in the function. We give constants and globals rank 0, arguments are
754 // numbered starting at one, and instructions are numbered in reverse post-order
755 // from where the arguments leave off. This gives instructions in loops higher
756 // values than instructions not in loops.
758 void CEE::BuildRankMap(Function &F) {
759 unsigned Rank = 1; // Skip rank zero.
761 // Number the arguments...
762 for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I)
765 // Number the instructions in reverse post order...
766 ReversePostOrderTraversal<Function*> RPOT(&F);
767 for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(),
768 E = RPOT.end(); I != E; ++I)
769 for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end();
771 if (BBI->getType() != Type::VoidTy)
772 RankMap[BBI] = Rank++;
776 // PropagateBranchInfo - When this method is invoked, we need to propagate
777 // information derived from the branch condition into the true and false
778 // branches of BI. Since we know that there aren't any critical edges in the
779 // flow graph, this can proceed unconditionally.
781 void CEE::PropagateBranchInfo(BranchInst *BI) {
782 assert(BI->isConditional() && "Must be a conditional branch!");
784 // Propagate information into the true block...
786 PropagateEquality(BI->getCondition(), ConstantInt::getTrue(),
787 getRegionInfo(BI->getSuccessor(0)));
789 // Propagate information into the false block...
791 PropagateEquality(BI->getCondition(), ConstantInt::getFalse(),
792 getRegionInfo(BI->getSuccessor(1)));
796 // PropagateSwitchInfo - We need to propagate the value tested by the
797 // switch statement through each case block.
799 void CEE::PropagateSwitchInfo(SwitchInst *SI) {
800 // Propagate information down each of our non-default case labels. We
801 // don't yet propagate information down the default label, because a
802 // potentially large number of inequality constraints provide less
803 // benefit per unit work than a single equality constraint.
805 Value *cond = SI->getCondition();
806 for (unsigned i = 1; i < SI->getNumSuccessors(); ++i)
807 PropagateEquality(cond, SI->getSuccessorValue(i),
808 getRegionInfo(SI->getSuccessor(i)));
812 // PropagateEquality - If we discover that two values are equal to each other in
813 // a specified region, propagate this knowledge recursively.
815 void CEE::PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI) {
816 if (Op0 == Op1) return; // Gee whiz. Are these really equal each other?
818 if (isa<Constant>(Op0)) // Make sure the constant is always Op1
821 // Make sure we don't already know these are equal, to avoid infinite loops...
822 ValueInfo &VI = RI.getValueInfo(Op0);
824 // Get information about the known relationship between Op0 & Op1
825 Relation &KnownRelation = VI.getRelation(Op1);
827 // If we already know they're equal, don't reprocess...
828 if (KnownRelation.getRelation() == FCmpInst::FCMP_OEQ ||
829 KnownRelation.getRelation() == ICmpInst::ICMP_EQ)
832 // If this is boolean, check to see if one of the operands is a constant. If
833 // it's a constant, then see if the other one is one of a setcc instruction,
834 // an AND, OR, or XOR instruction.
836 if (Op1->getType() == Type::Int1Ty)
837 if (ConstantInt *CB = dyn_cast<ConstantInt>(Op1)) {
839 if (Instruction *Inst = dyn_cast<Instruction>(Op0)) {
840 // If we know that this instruction is an AND instruction, and the result
841 // is true, this means that both operands to the OR are known to be true
844 if (CB->getBoolValue() && Inst->getOpcode() == Instruction::And) {
845 PropagateEquality(Inst->getOperand(0), CB, RI);
846 PropagateEquality(Inst->getOperand(1), CB, RI);
849 // If we know that this instruction is an OR instruction, and the result
850 // is false, this means that both operands to the OR are know to be false
853 if (!CB->getBoolValue() && Inst->getOpcode() == Instruction::Or) {
854 PropagateEquality(Inst->getOperand(0), CB, RI);
855 PropagateEquality(Inst->getOperand(1), CB, RI);
858 // If we know that this instruction is a NOT instruction, we know that the
859 // operand is known to be the inverse of whatever the current value is.
861 if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(Inst))
862 if (BinaryOperator::isNot(BOp))
863 PropagateEquality(BinaryOperator::getNotArgument(BOp),
864 ConstantInt::get(!CB->getBoolValue()), RI);
866 // If we know the value of a FCmp instruction, propagate the information
867 // about the relation into this region as well.
869 if (FCmpInst *FCI = dyn_cast<FCmpInst>(Inst)) {
870 if (CB->getBoolValue()) { // If we know the condition is true...
871 // Propagate info about the LHS to the RHS & RHS to LHS
872 PropagateRelation(FCI->getPredicate(), FCI->getOperand(0),
873 FCI->getOperand(1), RI);
874 PropagateRelation(FCI->getSwappedPredicate(),
875 FCI->getOperand(1), FCI->getOperand(0), RI);
877 } else { // If we know the condition is false...
878 // We know the opposite of the condition is true...
879 FCmpInst::Predicate C = FCI->getInversePredicate();
881 PropagateRelation(C, FCI->getOperand(0), FCI->getOperand(1), RI);
882 PropagateRelation(FCmpInst::getSwappedPredicate(C),
883 FCI->getOperand(1), FCI->getOperand(0), RI);
887 // If we know the value of a ICmp instruction, propagate the information
888 // about the relation into this region as well.
890 if (ICmpInst *ICI = dyn_cast<ICmpInst>(Inst)) {
891 if (CB->getBoolValue()) { // If we know the condition is true...
892 // Propagate info about the LHS to the RHS & RHS to LHS
893 PropagateRelation(ICI->getPredicate(), ICI->getOperand(0),
894 ICI->getOperand(1), RI);
895 PropagateRelation(ICI->getSwappedPredicate(), ICI->getOperand(1),
896 ICI->getOperand(1), RI);
898 } else { // If we know the condition is false ...
899 // We know the opposite of the condition is true...
900 ICmpInst::Predicate C = ICI->getInversePredicate();
902 PropagateRelation(C, ICI->getOperand(0), ICI->getOperand(1), RI);
903 PropagateRelation(ICmpInst::getSwappedPredicate(C),
904 ICI->getOperand(1), ICI->getOperand(0), RI);
910 // Propagate information about Op0 to Op1 & visa versa
911 PropagateRelation(ICmpInst::ICMP_EQ, Op0, Op1, RI);
912 PropagateRelation(ICmpInst::ICMP_EQ, Op1, Op0, RI);
913 PropagateRelation(FCmpInst::FCMP_OEQ, Op0, Op1, RI);
914 PropagateRelation(FCmpInst::FCMP_OEQ, Op1, Op0, RI);
918 // PropagateRelation - We know that the specified relation is true in all of the
919 // blocks in the specified region. Propagate the information about Op0 and
920 // anything derived from it into this region.
922 void CEE::PropagateRelation(unsigned Opcode, Value *Op0,
923 Value *Op1, RegionInfo &RI) {
924 assert(Op0->getType() == Op1->getType() && "Equal types expected!");
926 // Constants are already pretty well understood. We will apply information
927 // about the constant to Op1 in another call to PropagateRelation.
929 if (isa<Constant>(Op0)) return;
931 // Get the region information for this block to update...
932 ValueInfo &VI = RI.getValueInfo(Op0);
934 // Get information about the known relationship between Op0 & Op1
935 Relation &Op1R = VI.getRelation(Op1);
937 // Quick bailout for common case if we are reprocessing an instruction...
938 if (Op1R.getRelation() == Opcode)
941 // If we already have information that contradicts the current information we
942 // are propagating, ignore this info. Something bad must have happened!
944 if (Op1R.contradicts(Opcode, VI)) {
945 Op1R.contradicts(Opcode, VI);
946 cerr << "Contradiction found for opcode: "
947 << ((isa<ICmpInst>(Op0)||isa<ICmpInst>(Op1)) ?
948 Instruction::getOpcodeName(Instruction::ICmp) :
949 Instruction::getOpcodeName(Opcode))
951 Op1R.print(*cerr.stream());
955 // If the information propagated is new, then we want process the uses of this
956 // instruction to propagate the information down to them.
958 if (Op1R.incorporate(Opcode, VI))
959 UpdateUsersOfValue(Op0, RI);
963 // UpdateUsersOfValue - The information about V in this region has been updated.
964 // Propagate this to all consumers of the value.
966 void CEE::UpdateUsersOfValue(Value *V, RegionInfo &RI) {
967 for (Value::use_iterator I = V->use_begin(), E = V->use_end();
969 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
970 // If this is an instruction using a value that we know something about,
971 // try to propagate information to the value produced by the
972 // instruction. We can only do this if it is an instruction we can
973 // propagate information for (a setcc for example), and we only WANT to
974 // do this if the instruction dominates this region.
976 // If the instruction doesn't dominate this region, then it cannot be
977 // used in this region and we don't care about it. If the instruction
978 // is IN this region, then we will simplify the instruction before we
979 // get to uses of it anyway, so there is no reason to bother with it
980 // here. This check is also effectively checking to make sure that Inst
981 // is in the same function as our region (in case V is a global f.e.).
983 if (EF->properlyDominates(Inst->getParent(), RI.getEntryBlock()))
984 IncorporateInstruction(Inst, RI);
988 // IncorporateInstruction - We just updated the information about one of the
989 // operands to the specified instruction. Update the information about the
990 // value produced by this instruction
992 void CEE::IncorporateInstruction(Instruction *Inst, RegionInfo &RI) {
993 if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) {
994 // See if we can figure out a result for this instruction...
995 Relation::KnownResult Result = getCmpResult(CI, RI);
996 if (Result != Relation::Unknown) {
997 PropagateEquality(CI, ConstantInt::get(Result != 0), RI);
1003 // ComputeReplacements - Some values are known to be equal to other values in a
1004 // region. For example if there is a comparison of equality between a variable
1005 // X and a constant C, we can replace all uses of X with C in the region we are
1006 // interested in. We generalize this replacement to replace variables with
1007 // other variables if they are equal and there is a variable with lower rank
1008 // than the current one. This offers a canonicalizing property that exposes
1009 // more redundancies for later transformations to take advantage of.
1011 void CEE::ComputeReplacements(RegionInfo &RI) {
1012 // Loop over all of the values in the region info map...
1013 for (RegionInfo::iterator I = RI.begin(), E = RI.end(); I != E; ++I) {
1014 ValueInfo &VI = I->second;
1016 // If we know that this value is a particular constant, set Replacement to
1018 Value *Replacement = VI.getBounds().getSingleElement();
1020 // If this value is not known to be some constant, figure out the lowest
1021 // rank value that it is known to be equal to (if anything).
1023 if (Replacement == 0) {
1024 // Find out if there are any equality relationships with values of lower
1025 // rank than VI itself...
1026 unsigned MinRank = getRank(I->first);
1028 // Loop over the relationships known about Op0.
1029 const std::vector<Relation> &Relationships = VI.getRelationships();
1030 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
1031 if (Relationships[i].getRelation() == FCmpInst::FCMP_OEQ) {
1032 unsigned R = getRank(Relationships[i].getValue());
1035 Replacement = Relationships[i].getValue();
1038 else if (Relationships[i].getRelation() == ICmpInst::ICMP_EQ) {
1039 unsigned R = getRank(Relationships[i].getValue());
1042 Replacement = Relationships[i].getValue();
1047 // If we found something to replace this value with, keep track of it.
1049 VI.setReplacement(Replacement);
1053 // SimplifyBasicBlock - Given information about values in region RI, simplify
1054 // the instructions in the specified basic block.
1056 bool CEE::SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI) {
1057 bool Changed = false;
1058 for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ) {
1059 Instruction *Inst = I++;
1061 // Convert instruction arguments to canonical forms...
1062 Changed |= SimplifyInstruction(Inst, RI);
1064 if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) {
1065 // Try to simplify a setcc instruction based on inherited information
1066 Relation::KnownResult Result = getCmpResult(CI, RI);
1067 if (Result != Relation::Unknown) {
1068 DEBUG(cerr << "Replacing icmp with " << Result
1069 << " constant: " << *CI);
1071 CI->replaceAllUsesWith(ConstantInt::get((bool)Result));
1072 // The instruction is now dead, remove it from the program.
1073 CI->getParent()->getInstList().erase(CI);
1083 // SimplifyInstruction - Inspect the operands of the instruction, converting
1084 // them to their canonical form if possible. This takes care of, for example,
1085 // replacing a value 'X' with a constant 'C' if the instruction in question is
1086 // dominated by a true seteq 'X', 'C'.
1088 bool CEE::SimplifyInstruction(Instruction *I, const RegionInfo &RI) {
1089 bool Changed = false;
1091 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
1092 if (const ValueInfo *VI = RI.requestValueInfo(I->getOperand(i)))
1093 if (Value *Repl = VI->getReplacement()) {
1094 // If we know if a replacement with lower rank than Op0, make the
1096 DOUT << "In Inst: " << *I << " Replacing operand #" << i
1097 << " with " << *Repl << "\n";
1098 I->setOperand(i, Repl);
1106 // getCmpResult - Try to simplify a cmp instruction based on information
1107 // inherited from a dominating icmp instruction. V is one of the operands to
1108 // the icmp instruction, and VI is the set of information known about it. We
1109 // take two cases into consideration here. If the comparison is against a
1110 // constant value, we can use the constant range to see if the comparison is
1111 // possible to succeed. If it is not a comparison against a constant, we check
1112 // to see if there is a known relationship between the two values. If so, we
1113 // may be able to eliminate the check.
1115 Relation::KnownResult CEE::getCmpResult(CmpInst *CI,
1116 const RegionInfo &RI) {
1117 Value *Op0 = CI->getOperand(0), *Op1 = CI->getOperand(1);
1118 unsigned short predicate = CI->getPredicate();
1120 if (isa<Constant>(Op0)) {
1121 if (isa<Constant>(Op1)) {
1122 if (Constant *Result = ConstantFoldInstruction(CI)) {
1123 // Wow, this is easy, directly eliminate the ICmpInst.
1124 DEBUG(cerr << "Replacing cmp with constant fold: " << *CI);
1125 return cast<ConstantInt>(Result)->getBoolValue()
1126 ? Relation::KnownTrue : Relation::KnownFalse;
1129 // We want to swap this instruction so that operand #0 is the constant.
1130 std::swap(Op0, Op1);
1131 if (isa<ICmpInst>(CI))
1132 predicate = cast<ICmpInst>(CI)->getSwappedPredicate();
1134 predicate = cast<FCmpInst>(CI)->getSwappedPredicate();
1138 // Try to figure out what the result of this comparison will be...
1139 Relation::KnownResult Result = Relation::Unknown;
1141 // We have to know something about the relationship to prove anything...
1142 if (const ValueInfo *Op0VI = RI.requestValueInfo(Op0)) {
1144 // At this point, we know that if we have a constant argument that it is in
1145 // Op1. Check to see if we know anything about comparing value with a
1146 // constant, and if we can use this info to fold the icmp.
1148 if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
1149 // Check to see if we already know the result of this comparison...
1150 ConstantRange R = ConstantRange(predicate, C);
1151 ConstantRange Int = R.intersectWith(Op0VI->getBounds(),
1152 ICmpInst::isSignedPredicate(ICmpInst::Predicate(predicate)));
1154 // If the intersection of the two ranges is empty, then the condition
1155 // could never be true!
1157 if (Int.isEmptySet()) {
1158 Result = Relation::KnownFalse;
1160 // Otherwise, if VI.getBounds() (the possible values) is a subset of R
1161 // (the allowed values) then we know that the condition must always be
1164 } else if (Int == Op0VI->getBounds()) {
1165 Result = Relation::KnownTrue;
1168 // If we are here, we know that the second argument is not a constant
1169 // integral. See if we know anything about Op0 & Op1 that allows us to
1170 // fold this anyway.
1172 // Do we have value information about Op0 and a relation to Op1?
1173 if (const Relation *Op2R = Op0VI->requestRelation(Op1))
1174 Result = Op2R->getImpliedResult(predicate);
1180 //===----------------------------------------------------------------------===//
1181 // Relation Implementation
1182 //===----------------------------------------------------------------------===//
1184 // contradicts - Return true if the relationship specified by the operand
1185 // contradicts already known information.
1187 bool Relation::contradicts(unsigned Op,
1188 const ValueInfo &VI) const {
1189 assert (Op != Instruction::Add && "Invalid relation argument!");
1191 // If this is a relationship with a constant, make sure that this relationship
1192 // does not contradict properties known about the bounds of the constant.
1194 if (ConstantInt *C = dyn_cast<ConstantInt>(Val))
1195 if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
1196 Op <= ICmpInst::LAST_ICMP_PREDICATE)
1197 if (ConstantRange(Op, C).intersectWith(VI.getBounds(),
1198 ICmpInst::isSignedPredicate(ICmpInst::Predicate(Op))).isEmptySet())
1202 default: assert(0 && "Unknown Relationship code!");
1203 case Instruction::Add: return false; // Nothing known, nothing contradicts
1204 case ICmpInst::ICMP_EQ:
1205 return Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_SLT ||
1206 Op == ICmpInst::ICMP_UGT || Op == ICmpInst::ICMP_SGT ||
1207 Op == ICmpInst::ICMP_NE;
1208 case ICmpInst::ICMP_NE: return Op == ICmpInst::ICMP_EQ;
1209 case ICmpInst::ICMP_ULE:
1210 case ICmpInst::ICMP_SLE: return Op == ICmpInst::ICMP_UGT ||
1211 Op == ICmpInst::ICMP_SGT;
1212 case ICmpInst::ICMP_UGE:
1213 case ICmpInst::ICMP_SGE: return Op == ICmpInst::ICMP_ULT ||
1214 Op == ICmpInst::ICMP_SLT;
1215 case ICmpInst::ICMP_ULT:
1216 case ICmpInst::ICMP_SLT:
1217 return Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_UGT ||
1218 Op == ICmpInst::ICMP_SGT || Op == ICmpInst::ICMP_UGE ||
1219 Op == ICmpInst::ICMP_SGE;
1220 case ICmpInst::ICMP_UGT:
1221 case ICmpInst::ICMP_SGT:
1222 return Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_ULT ||
1223 Op == ICmpInst::ICMP_SLT || Op == ICmpInst::ICMP_ULE ||
1224 Op == ICmpInst::ICMP_SLE;
1225 case FCmpInst::FCMP_OEQ:
1226 return Op == FCmpInst::FCMP_OLT || Op == FCmpInst::FCMP_OGT ||
1227 Op == FCmpInst::FCMP_ONE;
1228 case FCmpInst::FCMP_ONE: return Op == FCmpInst::FCMP_OEQ;
1229 case FCmpInst::FCMP_OLE: return Op == FCmpInst::FCMP_OGT;
1230 case FCmpInst::FCMP_OGE: return Op == FCmpInst::FCMP_OLT;
1231 case FCmpInst::FCMP_OLT:
1232 return Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OGT ||
1233 Op == FCmpInst::FCMP_OGE;
1234 case FCmpInst::FCMP_OGT:
1235 return Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OLT ||
1236 Op == FCmpInst::FCMP_OLE;
1240 // incorporate - Incorporate information in the argument into this relation
1241 // entry. This assumes that the information doesn't contradict itself. If any
1242 // new information is gained, true is returned, otherwise false is returned to
1243 // indicate that nothing was updated.
1245 bool Relation::incorporate(unsigned Op, ValueInfo &VI) {
1246 assert(!contradicts(Op, VI) &&
1247 "Cannot incorporate contradictory information!");
1249 // If this is a relationship with a constant, make sure that we update the
1250 // range that is possible for the value to have...
1252 if (ConstantInt *C = dyn_cast<ConstantInt>(Val))
1253 if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
1254 Op <= ICmpInst::LAST_ICMP_PREDICATE)
1255 VI.getBounds() = ConstantRange(Op, C).intersectWith(VI.getBounds(),
1256 ICmpInst::isSignedPredicate(ICmpInst::Predicate(Op)));
1259 default: assert(0 && "Unknown prior value!");
1260 case Instruction::Add: Rel = Op; return true;
1261 case ICmpInst::ICMP_EQ:
1262 case ICmpInst::ICMP_NE:
1263 case ICmpInst::ICMP_ULT:
1264 case ICmpInst::ICMP_SLT:
1265 case ICmpInst::ICMP_UGT:
1266 case ICmpInst::ICMP_SGT: return false; // Nothing is more precise
1267 case ICmpInst::ICMP_ULE:
1268 case ICmpInst::ICMP_SLE:
1269 if (Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_ULT ||
1270 Op == ICmpInst::ICMP_SLT) {
1273 } else if (Op == ICmpInst::ICMP_NE) {
1274 Rel = Rel == ICmpInst::ICMP_ULE ? ICmpInst::ICMP_ULT :
1279 case ICmpInst::ICMP_UGE:
1280 case ICmpInst::ICMP_SGE:
1281 if (Op == ICmpInst::ICMP_EQ || ICmpInst::ICMP_UGT ||
1282 Op == ICmpInst::ICMP_SGT) {
1285 } else if (Op == ICmpInst::ICMP_NE) {
1286 Rel = Rel == ICmpInst::ICMP_UGE ? ICmpInst::ICMP_UGT :
1291 case FCmpInst::FCMP_OEQ: return false; // Nothing is more precise
1292 case FCmpInst::FCMP_ONE: return false; // Nothing is more precise
1293 case FCmpInst::FCMP_OLT: return false; // Nothing is more precise
1294 case FCmpInst::FCMP_OGT: return false; // Nothing is more precise
1295 case FCmpInst::FCMP_OLE:
1296 if (Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OLT) {
1299 } else if (Op == FCmpInst::FCMP_ONE) {
1300 Rel = FCmpInst::FCMP_OLT;
1304 case FCmpInst::FCMP_OGE:
1305 return Op == FCmpInst::FCMP_OLT;
1306 if (Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OGT) {
1309 } else if (Op == FCmpInst::FCMP_ONE) {
1310 Rel = FCmpInst::FCMP_OGT;
1317 // getImpliedResult - If this relationship between two values implies that
1318 // the specified relationship is true or false, return that. If we cannot
1319 // determine the result required, return Unknown.
1321 Relation::KnownResult
1322 Relation::getImpliedResult(unsigned Op) const {
1323 if (Rel == Op) return KnownTrue;
1324 if (Op >= ICmpInst::FIRST_ICMP_PREDICATE &&
1325 Op <= ICmpInst::LAST_ICMP_PREDICATE) {
1326 if (Rel == unsigned(ICmpInst::getInversePredicate(ICmpInst::Predicate(Op))))
1328 } else if (Op <= FCmpInst::LAST_FCMP_PREDICATE) {
1329 if (Rel == unsigned(FCmpInst::getInversePredicate(FCmpInst::Predicate(Op))))
1334 default: assert(0 && "Unknown prior value!");
1335 case ICmpInst::ICMP_EQ:
1336 if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_SLE ||
1337 Op == ICmpInst::ICMP_UGE || Op == ICmpInst::ICMP_SGE) return KnownTrue;
1338 if (Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_SLT ||
1339 Op == ICmpInst::ICMP_UGT || Op == ICmpInst::ICMP_SGT) return KnownFalse;
1341 case ICmpInst::ICMP_ULT:
1342 case ICmpInst::ICMP_SLT:
1343 if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_SLE ||
1344 Op == ICmpInst::ICMP_NE) return KnownTrue;
1345 if (Op == ICmpInst::ICMP_EQ) return KnownFalse;
1347 case ICmpInst::ICMP_UGT:
1348 case ICmpInst::ICMP_SGT:
1349 if (Op == ICmpInst::ICMP_UGE || Op == ICmpInst::ICMP_SGE ||
1350 Op == ICmpInst::ICMP_NE) return KnownTrue;
1351 if (Op == ICmpInst::ICMP_EQ) return KnownFalse;
1353 case FCmpInst::FCMP_OEQ:
1354 if (Op == FCmpInst::FCMP_OLE || Op == FCmpInst::FCMP_OGE) return KnownTrue;
1355 if (Op == FCmpInst::FCMP_OLT || Op == FCmpInst::FCMP_OGT) return KnownFalse;
1357 case FCmpInst::FCMP_OLT:
1358 if (Op == FCmpInst::FCMP_ONE || Op == FCmpInst::FCMP_OLE) return KnownTrue;
1359 if (Op == FCmpInst::FCMP_OEQ) return KnownFalse;
1361 case FCmpInst::FCMP_OGT:
1362 if (Op == FCmpInst::FCMP_ONE || Op == FCmpInst::FCMP_OGE) return KnownTrue;
1363 if (Op == FCmpInst::FCMP_OEQ) return KnownFalse;
1365 case ICmpInst::ICMP_NE:
1366 case ICmpInst::ICMP_SLE:
1367 case ICmpInst::ICMP_ULE:
1368 case ICmpInst::ICMP_UGE:
1369 case ICmpInst::ICMP_SGE:
1370 case FCmpInst::FCMP_ONE:
1371 case FCmpInst::FCMP_OLE:
1372 case FCmpInst::FCMP_OGE:
1373 case FCmpInst::FCMP_FALSE:
1374 case FCmpInst::FCMP_ORD:
1375 case FCmpInst::FCMP_UNO:
1376 case FCmpInst::FCMP_UEQ:
1377 case FCmpInst::FCMP_UGT:
1378 case FCmpInst::FCMP_UGE:
1379 case FCmpInst::FCMP_ULT:
1380 case FCmpInst::FCMP_ULE:
1381 case FCmpInst::FCMP_UNE:
1382 case FCmpInst::FCMP_TRUE:
1389 //===----------------------------------------------------------------------===//
1390 // Printing Support...
1391 //===----------------------------------------------------------------------===//
1393 // print - Implement the standard print form to print out analysis information.
1394 void CEE::print(std::ostream &O, const Module *M) const {
1395 O << "\nPrinting Correlated Expression Info:\n";
1396 for (std::map<BasicBlock*, RegionInfo>::const_iterator I =
1397 RegionInfoMap.begin(), E = RegionInfoMap.end(); I != E; ++I)
1401 // print - Output information about this region...
1402 void RegionInfo::print(std::ostream &OS) const {
1403 if (ValueMap.empty()) return;
1405 OS << " RegionInfo for basic block: " << BB->getName() << "\n";
1406 for (std::map<Value*, ValueInfo>::const_iterator
1407 I = ValueMap.begin(), E = ValueMap.end(); I != E; ++I)
1408 I->second.print(OS, I->first);
1412 // print - Output information about this value relation...
1413 void ValueInfo::print(std::ostream &OS, Value *V) const {
1414 if (Relationships.empty()) return;
1417 OS << " ValueInfo for: ";
1418 WriteAsOperand(OS, V);
1420 OS << "\n Bounds = " << Bounds << "\n";
1422 OS << " Replacement = ";
1423 WriteAsOperand(OS, Replacement);
1426 for (unsigned i = 0, e = Relationships.size(); i != e; ++i)
1427 Relationships[i].print(OS);
1430 // print - Output this relation to the specified stream
1431 void Relation::print(std::ostream &OS) const {
1434 default: OS << "*UNKNOWN*"; break;
1435 case ICmpInst::ICMP_EQ:
1436 case FCmpInst::FCMP_ORD:
1437 case FCmpInst::FCMP_UEQ:
1438 case FCmpInst::FCMP_OEQ: OS << "== "; break;
1439 case ICmpInst::ICMP_NE:
1440 case FCmpInst::FCMP_UNO:
1441 case FCmpInst::FCMP_UNE:
1442 case FCmpInst::FCMP_ONE: OS << "!= "; break;
1443 case ICmpInst::ICMP_ULT:
1444 case ICmpInst::ICMP_SLT:
1445 case FCmpInst::FCMP_ULT:
1446 case FCmpInst::FCMP_OLT: OS << "< "; break;
1447 case ICmpInst::ICMP_UGT:
1448 case ICmpInst::ICMP_SGT:
1449 case FCmpInst::FCMP_UGT:
1450 case FCmpInst::FCMP_OGT: OS << "> "; break;
1451 case ICmpInst::ICMP_ULE:
1452 case ICmpInst::ICMP_SLE:
1453 case FCmpInst::FCMP_ULE:
1454 case FCmpInst::FCMP_OLE: OS << "<= "; break;
1455 case ICmpInst::ICMP_UGE:
1456 case ICmpInst::ICMP_SGE:
1457 case FCmpInst::FCMP_UGE:
1458 case FCmpInst::FCMP_OGE: OS << ">= "; break;
1461 WriteAsOperand(OS, Val);
1465 // Don't inline these methods or else we won't be able to call them from GDB!
1466 void Relation::dump() const { print(*cerr.stream()); }
1467 void ValueInfo::dump() const { print(*cerr.stream(), 0); }
1468 void RegionInfo::dump() const { print(*cerr.stream()); }