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Diffstat (limited to 'lib/Transforms/Scalar/CorrelatedExprs.cpp')
| -rw-r--r-- | lib/Transforms/Scalar/CorrelatedExprs.cpp | 1487 |
1 files changed, 1487 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/CorrelatedExprs.cpp b/lib/Transforms/Scalar/CorrelatedExprs.cpp new file mode 100644 index 0000000..655f9eb --- /dev/null +++ b/lib/Transforms/Scalar/CorrelatedExprs.cpp @@ -0,0 +1,1487 @@ +//===- CorrelatedExprs.cpp - Pass to detect and eliminated c.e.'s ---------===// +// +// The LLVM Compiler Infrastructure +// +// This file was developed by the LLVM research group and is distributed under +// the University of Illinois Open Source License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// Correlated Expression Elimination propagates information from conditional +// branches to blocks dominated by destinations of the branch. It propagates +// information from the condition check itself into the body of the branch, +// allowing transformations like these for example: +// +// if (i == 7) +// ... 4*i; // constant propagation +// +// M = i+1; N = j+1; +// if (i == j) +// X = M-N; // = M-M == 0; +// +// This is called Correlated Expression Elimination because we eliminate or +// simplify expressions that are correlated with the direction of a branch. In +// this way we use static information to give us some information about the +// dynamic value of a variable. +// +//===----------------------------------------------------------------------===// + +#define DEBUG_TYPE "cee" +#include "llvm/Transforms/Scalar.h" +#include "llvm/Constants.h" +#include "llvm/Pass.h" +#include "llvm/Function.h" +#include "llvm/Instructions.h" +#include "llvm/Type.h" +#include "llvm/DerivedTypes.h" +#include "llvm/Analysis/ConstantFolding.h" +#include "llvm/Analysis/Dominators.h" +#include "llvm/Assembly/Writer.h" +#include "llvm/Transforms/Utils/BasicBlockUtils.h" +#include "llvm/Support/CFG.h" +#include "llvm/Support/Compiler.h" +#include "llvm/Support/ConstantRange.h" +#include "llvm/Support/Debug.h" +#include "llvm/ADT/PostOrderIterator.h" +#include "llvm/ADT/Statistic.h" +#include <algorithm> +using namespace llvm; + +STATISTIC(NumCmpRemoved, "Number of cmp instruction eliminated"); +STATISTIC(NumOperandsCann, "Number of operands canonicalized"); +STATISTIC(BranchRevectors, "Number of branches revectored"); + +namespace { + class ValueInfo; + class VISIBILITY_HIDDEN Relation { + Value *Val; // Relation to what value? + unsigned Rel; // SetCC or ICmp relation, or Add if no information + public: + Relation(Value *V) : Val(V), Rel(Instruction::Add) {} + bool operator<(const Relation &R) const { return Val < R.Val; } + Value *getValue() const { return Val; } + unsigned getRelation() const { return Rel; } + + // contradicts - Return true if the relationship specified by the operand + // contradicts already known information. + // + bool contradicts(unsigned Rel, const ValueInfo &VI) const; + + // incorporate - Incorporate information in the argument into this relation + // entry. This assumes that the information doesn't contradict itself. If + // any new information is gained, true is returned, otherwise false is + // returned to indicate that nothing was updated. + // + bool incorporate(unsigned Rel, ValueInfo &VI); + + // KnownResult - Whether or not this condition determines the result of a + // setcc or icmp in the program. False & True are intentionally 0 & 1 + // so we can convert to bool by casting after checking for unknown. + // + enum KnownResult { KnownFalse = 0, KnownTrue = 1, Unknown = 2 }; + + // getImpliedResult - If this relationship between two values implies that + // the specified relationship is true or false, return that. If we cannot + // determine the result required, return Unknown. + // + KnownResult getImpliedResult(unsigned Rel) const; + + // print - Output this relation to the specified stream + void print(std::ostream &OS) const; + void dump() const; + }; + + + // ValueInfo - One instance of this record exists for every value with + // relationships between other values. It keeps track of all of the + // relationships to other values in the program (specified with Relation) that + // are known to be valid in a region. + // + class VISIBILITY_HIDDEN ValueInfo { + // RelationShips - this value is know to have the specified relationships to + // other values. There can only be one entry per value, and this list is + // kept sorted by the Val field. + std::vector<Relation> Relationships; + + // If information about this value is known or propagated from constant + // expressions, this range contains the possible values this value may hold. + ConstantRange Bounds; + + // If we find that this value is equal to another value that has a lower + // rank, this value is used as it's replacement. + // + Value *Replacement; + public: + ValueInfo(const Type *Ty) + : Bounds(Ty->isInteger() ? cast<IntegerType>(Ty)->getBitWidth() : 32), + Replacement(0) {} + + // getBounds() - Return the constant bounds of the value... + const ConstantRange &getBounds() const { return Bounds; } + ConstantRange &getBounds() { return Bounds; } + + const std::vector<Relation> &getRelationships() { return Relationships; } + + // getReplacement - Return the value this value is to be replaced with if it + // exists, otherwise return null. + // + Value *getReplacement() const { return Replacement; } + + // setReplacement - Used by the replacement calculation pass to figure out + // what to replace this value with, if anything. + // + void setReplacement(Value *Repl) { Replacement = Repl; } + + // getRelation - return the relationship entry for the specified value. + // This can invalidate references to other Relations, so use it carefully. + // + Relation &getRelation(Value *V) { + // Binary search for V's entry... + std::vector<Relation>::iterator I = + std::lower_bound(Relationships.begin(), Relationships.end(), + Relation(V)); + + // If we found the entry, return it... + if (I != Relationships.end() && I->getValue() == V) + return *I; + + // Insert and return the new relationship... + return *Relationships.insert(I, V); + } + + const Relation *requestRelation(Value *V) const { + // Binary search for V's entry... + std::vector<Relation>::const_iterator I = + std::lower_bound(Relationships.begin(), Relationships.end(), + Relation(V)); + if (I != Relationships.end() && I->getValue() == V) + return &*I; + return 0; + } + + // print - Output information about this value relation... + void print(std::ostream &OS, Value *V) const; + void dump() const; + }; + + // RegionInfo - Keeps track of all of the value relationships for a region. A + // region is the are dominated by a basic block. RegionInfo's keep track of + // the RegionInfo for their dominator, because anything known in a dominator + // is known to be true in a dominated block as well. + // + class VISIBILITY_HIDDEN RegionInfo { + BasicBlock *BB; + + // ValueMap - Tracks the ValueInformation known for this region + typedef std::map<Value*, ValueInfo> ValueMapTy; + ValueMapTy ValueMap; + public: + RegionInfo(BasicBlock *bb) : BB(bb) {} + + // getEntryBlock - Return the block that dominates all of the members of + // this region. + BasicBlock *getEntryBlock() const { return BB; } + + // empty - return true if this region has no information known about it. + bool empty() const { return ValueMap.empty(); } + + const RegionInfo &operator=(const RegionInfo &RI) { + ValueMap = RI.ValueMap; + return *this; + } + + // print - Output information about this region... + void print(std::ostream &OS) const; + void dump() const; + + // Allow external access. + typedef ValueMapTy::iterator iterator; + iterator begin() { return ValueMap.begin(); } + iterator end() { return ValueMap.end(); } + + ValueInfo &getValueInfo(Value *V) { + ValueMapTy::iterator I = ValueMap.lower_bound(V); + if (I != ValueMap.end() && I->first == V) return I->second; + return ValueMap.insert(I, std::make_pair(V, V->getType()))->second; + } + + const ValueInfo *requestValueInfo(Value *V) const { + ValueMapTy::const_iterator I = ValueMap.find(V); + if (I != ValueMap.end()) return &I->second; + return 0; + } + + /// removeValueInfo - Remove anything known about V from our records. This + /// works whether or not we know anything about V. + /// + void removeValueInfo(Value *V) { + ValueMap.erase(V); + } + }; + + /// CEE - Correlated Expression Elimination + class VISIBILITY_HIDDEN CEE : public FunctionPass { + std::map<Value*, unsigned> RankMap; + std::map<BasicBlock*, RegionInfo> RegionInfoMap; + DominatorTree *DT; + public: + static char ID; // Pass identification, replacement for typeid + CEE() : FunctionPass((intptr_t)&ID) {} + + virtual bool runOnFunction(Function &F); + + // We don't modify the program, so we preserve all analyses + virtual void getAnalysisUsage(AnalysisUsage &AU) const { + AU.addRequired<DominatorTree>(); + AU.addRequiredID(BreakCriticalEdgesID); + }; + + // print - Implement the standard print form to print out analysis + // information. + virtual void print(std::ostream &O, const Module *M) const; + + private: + RegionInfo &getRegionInfo(BasicBlock *BB) { + std::map<BasicBlock*, RegionInfo>::iterator I + = RegionInfoMap.lower_bound(BB); + if (I != RegionInfoMap.end() && I->first == BB) return I->second; + return RegionInfoMap.insert(I, std::make_pair(BB, BB))->second; + } + + void BuildRankMap(Function &F); + unsigned getRank(Value *V) const { + if (isa<Constant>(V)) return 0; + std::map<Value*, unsigned>::const_iterator I = RankMap.find(V); + if (I != RankMap.end()) return I->second; + return 0; // Must be some other global thing + } + + bool TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks); + + bool ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo, + RegionInfo &RI); + + void ForwardSuccessorTo(TerminatorInst *TI, unsigned Succ, BasicBlock *D, + RegionInfo &RI); + void ReplaceUsesOfValueInRegion(Value *Orig, Value *New, + BasicBlock *RegionDominator); + void CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc, + std::vector<BasicBlock*> &RegionExitBlocks); + void InsertRegionExitMerges(PHINode *NewPHI, Instruction *OldVal, + const std::vector<BasicBlock*> &RegionExitBlocks); + + void PropagateBranchInfo(BranchInst *BI); + void PropagateSwitchInfo(SwitchInst *SI); + void PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI); + void PropagateRelation(unsigned Opcode, Value *Op0, + Value *Op1, RegionInfo &RI); + void UpdateUsersOfValue(Value *V, RegionInfo &RI); + void IncorporateInstruction(Instruction *Inst, RegionInfo &RI); + void ComputeReplacements(RegionInfo &RI); + + // getCmpResult - Given a icmp instruction, determine if the result is + // determined by facts we already know about the region under analysis. + // Return KnownTrue, KnownFalse, or UnKnown based on what we can determine. + Relation::KnownResult getCmpResult(CmpInst *ICI, const RegionInfo &RI); + + bool SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI); + bool SimplifyInstruction(Instruction *Inst, const RegionInfo &RI); + }; + + char CEE::ID = 0; + RegisterPass<CEE> X("cee", "Correlated Expression Elimination"); +} + +FunctionPass *llvm::createCorrelatedExpressionEliminationPass() { + return new CEE(); +} + + +bool CEE::runOnFunction(Function &F) { + // Build a rank map for the function... + BuildRankMap(F); + + // Traverse the dominator tree, computing information for each node in the + // tree. Note that our traversal will not even touch unreachable basic + // blocks. + DT = &getAnalysis<DominatorTree>(); + + std::set<BasicBlock*> VisitedBlocks; + bool Changed = TransformRegion(&F.getEntryBlock(), VisitedBlocks); + + RegionInfoMap.clear(); + RankMap.clear(); + return Changed; +} + +// TransformRegion - Transform the region starting with BB according to the +// calculated region information for the block. Transforming the region +// involves analyzing any information this block provides to successors, +// propagating the information to successors, and finally transforming +// successors. +// +// This method processes the function in depth first order, which guarantees +// that we process the immediate dominator of a block before the block itself. +// Because we are passing information from immediate dominators down to +// dominatees, we obviously have to process the information source before the +// information consumer. +// +bool CEE::TransformRegion(BasicBlock *BB, std::set<BasicBlock*> &VisitedBlocks){ + // Prevent infinite recursion... + if (VisitedBlocks.count(BB)) return false; + VisitedBlocks.insert(BB); + + // Get the computed region information for this block... + RegionInfo &RI = getRegionInfo(BB); + + // Compute the replacement information for this block... + ComputeReplacements(RI); + + // If debugging, print computed region information... + DEBUG(RI.print(*cerr.stream())); + + // Simplify the contents of this block... + bool Changed = SimplifyBasicBlock(*BB, RI); + + // Get the terminator of this basic block... + TerminatorInst *TI = BB->getTerminator(); + + // Loop over all of the blocks that this block is the immediate dominator for. + // Because all information known in this region is also known in all of the + // blocks that are dominated by this one, we can safely propagate the + // information down now. + // + DomTreeNode *BBDom = DT->getNode(BB); + if (!RI.empty()) { // Time opt: only propagate if we can change something + for (std::vector<DomTreeNode*>::iterator DI = BBDom->begin(), + E = BBDom->end(); DI != E; ++DI) { + BasicBlock *ChildBB = (*DI)->getBlock(); + assert(RegionInfoMap.find(ChildBB) == RegionInfoMap.end() && + "RegionInfo should be calculated in dominanace order!"); + getRegionInfo(ChildBB) = RI; + } + } + + // Now that all of our successors have information if they deserve it, + // propagate any information our terminator instruction finds to our + // successors. + if (BranchInst *BI = dyn_cast<BranchInst>(TI)) { + if (BI->isConditional()) + PropagateBranchInfo(BI); + } else if (SwitchInst *SI = dyn_cast<SwitchInst>(TI)) { + PropagateSwitchInfo(SI); + } + + // If this is a branch to a block outside our region that simply performs + // another conditional branch, one whose outcome is known inside of this + // region, then vector this outgoing edge directly to the known destination. + // + for (unsigned i = 0, e = TI->getNumSuccessors(); i != e; ++i) + while (ForwardCorrelatedEdgeDestination(TI, i, RI)) { + ++BranchRevectors; + Changed = true; + } + + // Now that all of our successors have information, recursively process them. + for (std::vector<DomTreeNode*>::iterator DI = BBDom->begin(), + E = BBDom->end(); DI != E; ++DI) { + BasicBlock *ChildBB = (*DI)->getBlock(); + Changed |= TransformRegion(ChildBB, VisitedBlocks); + } + + return Changed; +} + +// isBlockSimpleEnoughForCheck to see if the block is simple enough for us to +// revector the conditional branch in the bottom of the block, do so now. +// +static bool isBlockSimpleEnough(BasicBlock *BB) { + assert(isa<BranchInst>(BB->getTerminator())); + BranchInst *BI = cast<BranchInst>(BB->getTerminator()); + assert(BI->isConditional()); + + // Check the common case first: empty block, or block with just a setcc. + if (BB->size() == 1 || + (BB->size() == 2 && &BB->front() == BI->getCondition() && + BI->getCondition()->hasOneUse())) + return true; + + // Check the more complex case now... + BasicBlock::iterator I = BB->begin(); + + // FIXME: This should be reenabled once the regression with SIM is fixed! +#if 0 + // PHI Nodes are ok, just skip over them... + while (isa<PHINode>(*I)) ++I; +#endif + + // Accept the setcc instruction... + if (&*I == BI->getCondition()) + ++I; + + // Nothing else is acceptable here yet. We must not revector... unless we are + // at the terminator instruction. + if (&*I == BI) + return true; + + return false; +} + + +bool CEE::ForwardCorrelatedEdgeDestination(TerminatorInst *TI, unsigned SuccNo, + RegionInfo &RI) { + // If this successor is a simple block not in the current region, which + // contains only a conditional branch, we decide if the outcome of the branch + // can be determined from information inside of the region. Instead of going + // to this block, we can instead go to the destination we know is the right + // target. + // + + // Check to see if we dominate the block. If so, this block will get the + // condition turned to a constant anyway. + // + //if (EF->dominates(RI.getEntryBlock(), BB)) + // return 0; + + BasicBlock *BB = TI->getParent(); + + // Get the destination block of this edge... + BasicBlock *OldSucc = TI->getSuccessor(SuccNo); + + // Make sure that the block ends with a conditional branch and is simple + // enough for use to be able to revector over. + BranchInst *BI = dyn_cast<BranchInst>(OldSucc->getTerminator()); + if (BI == 0 || !BI->isConditional() || !isBlockSimpleEnough(OldSucc)) + return false; + + // We can only forward the branch over the block if the block ends with a + // cmp we can determine the outcome for. + // + // FIXME: we can make this more generic. Code below already handles more + // generic case. + if (!isa<CmpInst>(BI->getCondition())) + return false; + + // Make a new RegionInfo structure so that we can simulate the effect of the + // PHI nodes in the block we are skipping over... + // + RegionInfo NewRI(RI); + + // Remove value information for all of the values we are simulating... to make + // sure we don't have any stale information. + for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I) + if (I->getType() != Type::VoidTy) + NewRI.removeValueInfo(I); + + // Put the newly discovered information into the RegionInfo... + for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); I!=E; ++I) + if (PHINode *PN = dyn_cast<PHINode>(I)) { + int OpNum = PN->getBasicBlockIndex(BB); + assert(OpNum != -1 && "PHI doesn't have incoming edge for predecessor!?"); + PropagateEquality(PN, PN->getIncomingValue(OpNum), NewRI); + } else if (CmpInst *CI = dyn_cast<CmpInst>(I)) { + Relation::KnownResult Res = getCmpResult(CI, NewRI); + if (Res == Relation::Unknown) return false; + PropagateEquality(CI, ConstantInt::get(Type::Int1Ty, Res), NewRI); + } else { + assert(isa<BranchInst>(*I) && "Unexpected instruction type!"); + } + + // Compute the facts implied by what we have discovered... + ComputeReplacements(NewRI); + + ValueInfo &PredicateVI = NewRI.getValueInfo(BI->getCondition()); + if (PredicateVI.getReplacement() && + isa<Constant>(PredicateVI.getReplacement()) && + !isa<GlobalValue>(PredicateVI.getReplacement())) { + ConstantInt *CB = cast<ConstantInt>(PredicateVI.getReplacement()); + + // Forward to the successor that corresponds to the branch we will take. + ForwardSuccessorTo(TI, SuccNo, + BI->getSuccessor(!CB->getZExtValue()), NewRI); + return true; + } + + return false; +} + +static Value *getReplacementOrValue(Value *V, RegionInfo &RI) { + if (const ValueInfo *VI = RI.requestValueInfo(V)) + if (Value *Repl = VI->getReplacement()) + return Repl; + return V; +} + +/// ForwardSuccessorTo - We have found that we can forward successor # 'SuccNo' +/// of Terminator 'TI' to the 'Dest' BasicBlock. This method performs the +/// mechanics of updating SSA information and revectoring the branch. +/// +void CEE::ForwardSuccessorTo(TerminatorInst *TI, unsigned SuccNo, + BasicBlock *Dest, RegionInfo &RI) { + // If there are any PHI nodes in the Dest BB, we must duplicate the entry + // in the PHI node for the old successor to now include an entry from the + // current basic block. + // + BasicBlock *OldSucc = TI->getSuccessor(SuccNo); + BasicBlock *BB = TI->getParent(); + + DOUT << "Forwarding branch in basic block %" << BB->getName() + << " from block %" << OldSucc->getName() << " to block %" + << Dest->getName() << "\n" + << "Before forwarding: " << *BB->getParent(); + + // Because we know that there cannot be critical edges in the flow graph, and + // that OldSucc has multiple outgoing edges, this means that Dest cannot have + // multiple incoming edges. + // +#ifndef NDEBUG + pred_iterator DPI = pred_begin(Dest); ++DPI; + assert(DPI == pred_end(Dest) && "Critical edge found!!"); +#endif + + // Loop over any PHI nodes in the destination, eliminating them, because they + // may only have one input. + // + while (PHINode *PN = dyn_cast<PHINode>(&Dest->front())) { + assert(PN->getNumIncomingValues() == 1 && "Crit edge found!"); + // Eliminate the PHI node + PN->replaceAllUsesWith(PN->getIncomingValue(0)); + Dest->getInstList().erase(PN); + } + + // If there are values defined in the "OldSucc" basic block, we need to insert + // PHI nodes in the regions we are dealing with to emulate them. This can + // insert dead phi nodes, but it is more trouble to see if they are used than + // to just blindly insert them. + // + if (DT->dominates(OldSucc, Dest)) { + // RegionExitBlocks - Find all of the blocks that are not dominated by Dest, + // but have predecessors that are. Additionally, prune down the set to only + // include blocks that are dominated by OldSucc as well. + // + std::vector<BasicBlock*> RegionExitBlocks; + CalculateRegionExitBlocks(Dest, OldSucc, RegionExitBlocks); + + for (BasicBlock::iterator I = OldSucc->begin(), E = OldSucc->end(); + I != E; ++I) + if (I->getType() != Type::VoidTy) { + // Create and insert the PHI node into the top of Dest. + PHINode *NewPN = new PHINode(I->getType(), I->getName()+".fw_merge", + Dest->begin()); + // There is definitely an edge from OldSucc... add the edge now + NewPN->addIncoming(I, OldSucc); + + // There is also an edge from BB now, add the edge with the calculated + // value from the RI. + NewPN->addIncoming(getReplacementOrValue(I, RI), BB); + + // Make everything in the Dest region use the new PHI node now... + ReplaceUsesOfValueInRegion(I, NewPN, Dest); + + // Make sure that exits out of the region dominated by NewPN get PHI + // nodes that merge the values as appropriate. + InsertRegionExitMerges(NewPN, I, RegionExitBlocks); + } + } + + // If there were PHI nodes in OldSucc, we need to remove the entry for this + // edge from the PHI node, and we need to replace any references to the PHI + // node with a new value. + // + for (BasicBlock::iterator I = OldSucc->begin(); isa<PHINode>(I); ) { + PHINode *PN = cast<PHINode>(I); + + // Get the value flowing across the old edge and remove the PHI node entry + // for this edge: we are about to remove the edge! Don't remove the PHI + // node yet though if this is the last edge into it. + Value *EdgeValue = PN->removeIncomingValue(BB, false); + + // Make sure that anything that used to use PN now refers to EdgeValue + ReplaceUsesOfValueInRegion(PN, EdgeValue, Dest); + + // If there is only one value left coming into the PHI node, replace the PHI + // node itself with the one incoming value left. + // + if (PN->getNumIncomingValues() == 1) { + assert(PN->getNumIncomingValues() == 1); + PN->replaceAllUsesWith(PN->getIncomingValue(0)); + PN->getParent()->getInstList().erase(PN); + I = OldSucc->begin(); + } else if (PN->getNumIncomingValues() == 0) { // Nuke the PHI + // If we removed the last incoming value to this PHI, nuke the PHI node + // now. + PN->replaceAllUsesWith(Constant::getNullValue(PN->getType())); + PN->getParent()->getInstList().erase(PN); + I = OldSucc->begin(); + } else { + ++I; // Otherwise, move on to the next PHI node + } + } + + // Actually revector the branch now... + TI->setSuccessor(SuccNo, Dest); + + // If we just introduced a critical edge in the flow graph, make sure to break + // it right away... + SplitCriticalEdge(TI, SuccNo, this); + + // Make sure that we don't introduce critical edges from oldsucc now! + for (unsigned i = 0, e = OldSucc->getTerminator()->getNumSuccessors(); + i != e; ++i) + SplitCriticalEdge(OldSucc->getTerminator(), i, this); + + // Since we invalidated the CFG, recalculate the dominator set so that it is + // useful for later processing! + // FIXME: This is much worse than it really should be! + //EF->recalculate(); + + DOUT << "After forwarding: " << *BB->getParent(); +} + +/// ReplaceUsesOfValueInRegion - This method replaces all uses of Orig with uses +/// of New. It only affects instructions that are defined in basic blocks that +/// are dominated by Head. +/// +void CEE::ReplaceUsesOfValueInRegion(Value *Orig, Value *New, + BasicBlock *RegionDominator) { + assert(Orig != New && "Cannot replace value with itself"); + std::vector<Instruction*> InstsToChange; + std::vector<PHINode*> PHIsToChange; + InstsToChange.reserve(Orig->getNumUses()); + + // Loop over instructions adding them to InstsToChange vector, this allows us + // an easy way to avoid invalidating the use_iterator at a bad time. + for (Value::use_iterator I = Orig->use_begin(), E = Orig->use_end(); + I != E; ++I) + if (Instruction *User = dyn_cast<Instruction>(*I)) + if (DT->dominates(RegionDominator, User->getParent())) + InstsToChange.push_back(User); + else if (PHINode *PN = dyn_cast<PHINode>(User)) { + PHIsToChange.push_back(PN); + } + + // PHIsToChange contains PHI nodes that use Orig that do not live in blocks + // dominated by orig. If the block the value flows in from is dominated by + // RegionDominator, then we rewrite the PHI + for (unsigned i = 0, e = PHIsToChange.size(); i != e; ++i) { + PHINode *PN = PHIsToChange[i]; + for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j) + if (PN->getIncomingValue(j) == Orig && + DT->dominates(RegionDominator, PN->getIncomingBlock(j))) + PN->setIncomingValue(j, New); + } + + // Loop over the InstsToChange list, replacing all uses of Orig with uses of + // New. This list contains all of the instructions in our region that use + // Orig. + for (unsigned i = 0, e = InstsToChange.size(); i != e; ++i) + if (PHINode *PN = dyn_cast<PHINode>(InstsToChange[i])) { + // PHINodes must be handled carefully. If the PHI node itself is in the + // region, we have to make sure to only do the replacement for incoming + // values that correspond to basic blocks in the region. + for (unsigned j = 0, e = PN->getNumIncomingValues(); j != e; ++j) + if (PN->getIncomingValue(j) == Orig && + DT->dominates(RegionDominator, PN->getIncomingBlock(j))) + PN->setIncomingValue(j, New); + + } else { + InstsToChange[i]->replaceUsesOfWith(Orig, New); + } +} + +static void CalcRegionExitBlocks(BasicBlock *Header, BasicBlock *BB, + std::set<BasicBlock*> &Visited, + DominatorTree &DT, + std::vector<BasicBlock*> &RegionExitBlocks) { + if (Visited.count(BB)) return; + Visited.insert(BB); + + if (DT.dominates(Header, BB)) { // Block in the region, recursively traverse + for (succ_iterator I = succ_begin(BB), E = succ_end(BB); I != E; ++I) + CalcRegionExitBlocks(Header, *I, Visited, DT, RegionExitBlocks); + } else { + // Header does not dominate this block, but we have a predecessor that does + // dominate us. Add ourself to the list. + RegionExitBlocks.push_back(BB); + } +} + +/// CalculateRegionExitBlocks - Find all of the blocks that are not dominated by +/// BB, but have predecessors that are. Additionally, prune down the set to +/// only include blocks that are dominated by OldSucc as well. +/// +void CEE::CalculateRegionExitBlocks(BasicBlock *BB, BasicBlock *OldSucc, + std::vector<BasicBlock*> &RegionExitBlocks){ + std::set<BasicBlock*> Visited; // Don't infinite loop + + // Recursively calculate blocks we are interested in... + CalcRegionExitBlocks(BB, BB, Visited, *DT, RegionExitBlocks); + + // Filter out blocks that are not dominated by OldSucc... + for (unsigned i = 0; i != RegionExitBlocks.size(); ) { + if (DT->dominates(OldSucc, RegionExitBlocks[i])) + ++i; // Block is ok, keep it. + else { + // Move to end of list... + std::swap(RegionExitBlocks[i], RegionExitBlocks.back()); + RegionExitBlocks.pop_back(); // Nuke the end + } + } +} + +void CEE::InsertRegionExitMerges(PHINode *BBVal, Instruction *OldVal, + const std::vector<BasicBlock*> &RegionExitBlocks) { + assert(BBVal->getType() == OldVal->getType() && "Should be derived values!"); + BasicBlock *BB = BBVal->getParent(); + + // Loop over all of the blocks we have to place PHIs in, doing it. + for (unsigned i = 0, e = RegionExitBlocks.size(); i != e; ++i) { + BasicBlock *FBlock = RegionExitBlocks[i]; // Block on the frontier + + // Create the new PHI node + PHINode *NewPN = new PHINode(BBVal->getType(), + OldVal->getName()+".fw_frontier", + FBlock->begin()); + + // Add an incoming value for every predecessor of the block... + for (pred_iterator PI = pred_begin(FBlock), PE = pred_end(FBlock); + PI != PE; ++PI) { + // If the incoming edge is from the region dominated by BB, use BBVal, + // otherwise use OldVal. + NewPN->addIncoming(DT->dominates(BB, *PI) ? BBVal : OldVal, *PI); + } + + // Now make everyone dominated by this block use this new value! + ReplaceUsesOfValueInRegion(OldVal, NewPN, FBlock); + } +} + + + +// BuildRankMap - This method builds the rank map data structure which gives +// each instruction/value in the function a value based on how early it appears +// in the function. We give constants and globals rank 0, arguments are +// numbered starting at one, and instructions are numbered in reverse post-order +// from where the arguments leave off. This gives instructions in loops higher +// values than instructions not in loops. +// +void CEE::BuildRankMap(Function &F) { + unsigned Rank = 1; // Skip rank zero. + + // Number the arguments... + for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I) + RankMap[I] = Rank++; + + // Number the instructions in reverse post order... + ReversePostOrderTraversal<Function*> RPOT(&F); + for (ReversePostOrderTraversal<Function*>::rpo_iterator I = RPOT.begin(), + E = RPOT.end(); I != E; ++I) + for (BasicBlock::iterator BBI = (*I)->begin(), E = (*I)->end(); + BBI != E; ++BBI) + if (BBI->getType() != Type::VoidTy) + RankMap[BBI] = Rank++; +} + + +// PropagateBranchInfo - When this method is invoked, we need to propagate +// information derived from the branch condition into the true and false +// branches of BI. Since we know that there aren't any critical edges in the +// flow graph, this can proceed unconditionally. +// +void CEE::PropagateBranchInfo(BranchInst *BI) { + assert(BI->isConditional() && "Must be a conditional branch!"); + + // Propagate information into the true block... + // + PropagateEquality(BI->getCondition(), ConstantInt::getTrue(), + getRegionInfo(BI->getSuccessor(0))); + + // Propagate information into the false block... + // + PropagateEquality(BI->getCondition(), ConstantInt::getFalse(), + getRegionInfo(BI->getSuccessor(1))); +} + + +// PropagateSwitchInfo - We need to propagate the value tested by the +// switch statement through each case block. +// +void CEE::PropagateSwitchInfo(SwitchInst *SI) { + // Propagate information down each of our non-default case labels. We + // don't yet propagate information down the default label, because a + // potentially large number of inequality constraints provide less + // benefit per unit work than a single equality constraint. + // + Value *cond = SI->getCondition(); + for (unsigned i = 1; i < SI->getNumSuccessors(); ++i) + PropagateEquality(cond, SI->getSuccessorValue(i), + getRegionInfo(SI->getSuccessor(i))); +} + + +// PropagateEquality - If we discover that two values are equal to each other in +// a specified region, propagate this knowledge recursively. +// +void CEE::PropagateEquality(Value *Op0, Value *Op1, RegionInfo &RI) { + if (Op0 == Op1) return; // Gee whiz. Are these really equal each other? + + if (isa<Constant>(Op0)) // Make sure the constant is always Op1 + std::swap(Op0, Op1); + + // Make sure we don't already know these are equal, to avoid infinite loops... + ValueInfo &VI = RI.getValueInfo(Op0); + + // Get information about the known relationship between Op0 & Op1 + Relation &KnownRelation = VI.getRelation(Op1); + + // If we already know they're equal, don't reprocess... + if (KnownRelation.getRelation() == FCmpInst::FCMP_OEQ || + KnownRelation.getRelation() == ICmpInst::ICMP_EQ) + return; + + // If this is boolean, check to see if one of the operands is a constant. If + // it's a constant, then see if the other one is one of a setcc instruction, + // an AND, OR, or XOR instruction. + // + ConstantInt *CB = dyn_cast<ConstantInt>(Op1); + if (CB && Op1->getType() == Type::Int1Ty) { + if (Instruction *Inst = dyn_cast<Instruction>(Op0)) { + // If we know that this instruction is an AND instruction, and the + // result is true, this means that both operands to the OR are known + // to be true as well. + // + if (CB->getZExtValue() && Inst->getOpcode() == Instruction::And) { + PropagateEquality(Inst->getOperand(0), CB, RI); + PropagateEquality(Inst->getOperand(1), CB, RI); + } + + // If we know that this instruction is an OR instruction, and the result + // is false, this means that both operands to the OR are know to be + // false as well. + // + if (!CB->getZExtValue() && Inst->getOpcode() == Instruction::Or) { + PropagateEquality(Inst->getOperand(0), CB, RI); + PropagateEquality(Inst->getOperand(1), CB, RI); + } + + // If we know that this instruction is a NOT instruction, we know that + // the operand is known to be the inverse of whatever the current + // value is. + // + if (BinaryOperator *BOp = dyn_cast<BinaryOperator>(Inst)) + if (BinaryOperator::isNot(BOp)) + PropagateEquality(BinaryOperator::getNotArgument(BOp), + ConstantInt::get(Type::Int1Ty, + !CB->getZExtValue()), RI); + + // If we know the value of a FCmp instruction, propagate the information + // about the relation into this region as well. + // + if (FCmpInst *FCI = dyn_cast<FCmpInst>(Inst)) { + if (CB->getZExtValue()) { // If we know the condition is true... + // Propagate info about the LHS to the RHS & RHS to LHS + PropagateRelation(FCI->getPredicate(), FCI->getOperand(0), + FCI->getOperand(1), RI); + PropagateRelation(FCI->getSwappedPredicate(), + FCI->getOperand(1), FCI->getOperand(0), RI); + + } else { // If we know the condition is false... + // We know the opposite of the condition is true... + FCmpInst::Predicate C = FCI->getInversePredicate(); + + PropagateRelation(C, FCI->getOperand(0), FCI->getOperand(1), RI); + PropagateRelation(FCmpInst::getSwappedPredicate(C), + FCI->getOperand(1), FCI->getOperand(0), RI); + } + } + + // If we know the value of a ICmp instruction, propagate the information + // about the relation into this region as well. + // + if (ICmpInst *ICI = dyn_cast<ICmpInst>(Inst)) { + if (CB->getZExtValue()) { // If we know the condition is true... + // Propagate info about the LHS to the RHS & RHS to LHS + PropagateRelation(ICI->getPredicate(), ICI->getOperand(0), + ICI->getOperand(1), RI); + PropagateRelation(ICI->getSwappedPredicate(), ICI->getOperand(1), + ICI->getOperand(1), RI); + + } else { // If we know the condition is false ... + // We know the opposite of the condition is true... + ICmpInst::Predicate C = ICI->getInversePredicate(); + + PropagateRelation(C, ICI->getOperand(0), ICI->getOperand(1), RI); + PropagateRelation(ICmpInst::getSwappedPredicate(C), + ICI->getOperand(1), ICI->getOperand(0), RI); + } + } + } + } + + // Propagate information about Op0 to Op1 & visa versa + PropagateRelation(ICmpInst::ICMP_EQ, Op0, Op1, RI); + PropagateRelation(ICmpInst::ICMP_EQ, Op1, Op0, RI); + PropagateRelation(FCmpInst::FCMP_OEQ, Op0, Op1, RI); + PropagateRelation(FCmpInst::FCMP_OEQ, Op1, Op0, RI); +} + + +// PropagateRelation - We know that the specified relation is true in all of the +// blocks in the specified region. Propagate the information about Op0 and +// anything derived from it into this region. +// +void CEE::PropagateRelation(unsigned Opcode, Value *Op0, + Value *Op1, RegionInfo &RI) { + assert(Op0->getType() == Op1->getType() && "Equal types expected!"); + + // Constants are already pretty well understood. We will apply information + // about the constant to Op1 in another call to PropagateRelation. + // + if (isa<Constant>(Op0)) return; + + // Get the region information for this block to update... + ValueInfo &VI = RI.getValueInfo(Op0); + + // Get information about the known relationship between Op0 & Op1 + Relation &Op1R = VI.getRelation(Op1); + + // Quick bailout for common case if we are reprocessing an instruction... + if (Op1R.getRelation() == Opcode) + return; + + // If we already have information that contradicts the current information we + // are propagating, ignore this info. Something bad must have happened! + // + if (Op1R.contradicts(Opcode, VI)) { + Op1R.contradicts(Opcode, VI); + cerr << "Contradiction found for opcode: " + << ((isa<ICmpInst>(Op0)||isa<ICmpInst>(Op1)) ? + Instruction::getOpcodeName(Instruction::ICmp) : + Instruction::getOpcodeName(Opcode)) + << "\n"; + Op1R.print(*cerr.stream()); + return; + } + + // If the information propagated is new, then we want process the uses of this + // instruction to propagate the information down to them. + // + if (Op1R.incorporate(Opcode, VI)) + UpdateUsersOfValue(Op0, RI); +} + + +// UpdateUsersOfValue - The information about V in this region has been updated. +// Propagate this to all consumers of the value. +// +void CEE::UpdateUsersOfValue(Value *V, RegionInfo &RI) { + for (Value::use_iterator I = V->use_begin(), E = V->use_end(); + I != E; ++I) + if (Instruction *Inst = dyn_cast<Instruction>(*I)) { + // If this is an instruction using a value that we know something about, + // try to propagate information to the value produced by the + // instruction. We can only do this if it is an instruction we can + // propagate information for (a setcc for example), and we only WANT to + // do this if the instruction dominates this region. + // + // If the instruction doesn't dominate this region, then it cannot be + // used in this region and we don't care about it. If the instruction + // is IN this region, then we will simplify the instruction before we + // get to uses of it anyway, so there is no reason to bother with it + // here. This check is also effectively checking to make sure that Inst + // is in the same function as our region (in case V is a global f.e.). + // + if (DT->properlyDominates(Inst->getParent(), RI.getEntryBlock())) + IncorporateInstruction(Inst, RI); + } +} + +// IncorporateInstruction - We just updated the information about one of the +// operands to the specified instruction. Update the information about the +// value produced by this instruction +// +void CEE::IncorporateInstruction(Instruction *Inst, RegionInfo &RI) { + if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) { + // See if we can figure out a result for this instruction... + Relation::KnownResult Result = getCmpResult(CI, RI); + if (Result != Relation::Unknown) { + PropagateEquality(CI, ConstantInt::get(Type::Int1Ty, Result != 0), RI); + } + } +} + + +// ComputeReplacements - Some values are known to be equal to other values in a +// region. For example if there is a comparison of equality between a variable +// X and a constant C, we can replace all uses of X with C in the region we are +// interested in. We generalize this replacement to replace variables with +// other variables if they are equal and there is a variable with lower rank +// than the current one. This offers a canonicalizing property that exposes +// more redundancies for later transformations to take advantage of. +// +void CEE::ComputeReplacements(RegionInfo &RI) { + // Loop over all of the values in the region info map... + for (RegionInfo::iterator I = RI.begin(), E = RI.end(); I != E; ++I) { + ValueInfo &VI = I->second; + + // If we know that this value is a particular constant, set Replacement to + // the constant... + Value *Replacement = 0; + const APInt * Rplcmnt = VI.getBounds().getSingleElement(); + if (Rplcmnt) + Replacement = ConstantInt::get(*Rplcmnt); + + // If this value is not known to be some constant, figure out the lowest + // rank value that it is known to be equal to (if anything). + // + if (Replacement == 0) { + // Find out if there are any equality relationships with values of lower + // rank than VI itself... + unsigned MinRank = getRank(I->first); + + // Loop over the relationships known about Op0. + const std::vector<Relation> &Relationships = VI.getRelationships(); + for (unsigned i = 0, e = Relationships.size(); i != e; ++i) + if (Relationships[i].getRelation() == FCmpInst::FCMP_OEQ) { + unsigned R = getRank(Relationships[i].getValue()); + if (R < MinRank) { + MinRank = R; + Replacement = Relationships[i].getValue(); + } + } + else if (Relationships[i].getRelation() == ICmpInst::ICMP_EQ) { + unsigned R = getRank(Relationships[i].getValue()); + if (R < MinRank) { + MinRank = R; + Replacement = Relationships[i].getValue(); + } + } + } + + // If we found something to replace this value with, keep track of it. + if (Replacement) + VI.setReplacement(Replacement); + } +} + +// SimplifyBasicBlock - Given information about values in region RI, simplify +// the instructions in the specified basic block. +// +bool CEE::SimplifyBasicBlock(BasicBlock &BB, const RegionInfo &RI) { + bool Changed = false; + for (BasicBlock::iterator I = BB.begin(), E = BB.end(); I != E; ) { + Instruction *Inst = I++; + + // Convert instruction arguments to canonical forms... + Changed |= SimplifyInstruction(Inst, RI); + + if (CmpInst *CI = dyn_cast<CmpInst>(Inst)) { + // Try to simplify a setcc instruction based on inherited information + Relation::KnownResult Result = getCmpResult(CI, RI); + if (Result != Relation::Unknown) { + DEBUG(cerr << "Replacing icmp with " << Result + << " constant: " << *CI); + + CI->replaceAllUsesWith(ConstantInt::get(Type::Int1Ty, (bool)Result)); + // The instruction is now dead, remove it from the program. + CI->getParent()->getInstList().erase(CI); + ++NumCmpRemoved; + Changed = true; + } + } + } + + return Changed; +} + +// SimplifyInstruction - Inspect the operands of the instruction, converting +// them to their canonical form if possible. This takes care of, for example, +// replacing a value 'X' with a constant 'C' if the instruction in question is +// dominated by a true seteq 'X', 'C'. +// +bool CEE::SimplifyInstruction(Instruction *I, const RegionInfo &RI) { + bool Changed = false; + + for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) + if (const ValueInfo *VI = RI.requestValueInfo(I->getOperand(i))) + if (Value *Repl = VI->getReplacement()) { + // If we know if a replacement with lower rank than Op0, make the + // replacement now. + DOUT << "In Inst: " << *I << " Replacing operand #" << i + << " with " << *Repl << "\n"; + I->setOperand(i, Repl); + Changed = true; + ++NumOperandsCann; + } + + return Changed; +} + +// getCmpResult - Try to simplify a cmp instruction based on information +// inherited from a dominating icmp instruction. V is one of the operands to +// the icmp instruction, and VI is the set of information known about it. We +// take two cases into consideration here. If the comparison is against a +// constant value, we can use the constant range to see if the comparison is +// possible to succeed. If it is not a comparison against a constant, we check +// to see if there is a known relationship between the two values. If so, we +// may be able to eliminate the check. +// +Relation::KnownResult CEE::getCmpResult(CmpInst *CI, + const RegionInfo &RI) { + Value *Op0 = CI->getOperand(0), *Op1 = CI->getOperand(1); + unsigned short predicate = CI->getPredicate(); + + if (isa<Constant>(Op0)) { + if (isa<Constant>(Op1)) { + if (Constant *Result = ConstantFoldInstruction(CI)) { + // Wow, this is easy, directly eliminate the ICmpInst. + DEBUG(cerr << "Replacing cmp with constant fold: " << *CI); + return cast<ConstantInt>(Result)->getZExtValue() + ? Relation::KnownTrue : Relation::KnownFalse; + } + } else { + // We want to swap this instruction so that operand #0 is the constant. + std::swap(Op0, Op1); + if (isa<ICmpInst>(CI)) + predicate = cast<ICmpInst>(CI)->getSwappedPredicate(); + else + predicate = cast<FCmpInst>(CI)->getSwappedPredicate(); + } + } + + // Try to figure out what the result of this comparison will be... + Relation::KnownResult Result = Relation::Unknown; + + // We have to know something about the relationship to prove anything... + if (const ValueInfo *Op0VI = RI.requestValueInfo(Op0)) { + + // At this point, we know that if we have a constant argument that it is in + // Op1. Check to see if we know anything about comparing value with a + // constant, and if we can use this info to fold the icmp. + // + if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) { + // Check to see if we already know the result of this comparison... + ICmpInst::Predicate ipred = ICmpInst::Predicate(predicate); + ConstantRange R = ICmpInst::makeConstantRange(ipred, C->getValue()); + ConstantRange Int = R.intersectWith(Op0VI->getBounds()); + + // If the intersection of the two ranges is empty, then the condition + // could never be true! + // + if (Int.isEmptySet()) { + Result = Relation::KnownFalse; + + // Otherwise, if VI.getBounds() (the possible values) is a subset of R + // (the allowed values) then we know that the condition must always be + // true! + // + } else if (Int == Op0VI->getBounds()) { + Result = Relation::KnownTrue; + } + } else { + // If we are here, we know that the second argument is not a constant + // integral. See if we know anything about Op0 & Op1 that allows us to + // fold this anyway. + // + // Do we have value information about Op0 and a relation to Op1? + if (const Relation *Op2R = Op0VI->requestRelation(Op1)) + Result = Op2R->getImpliedResult(predicate); + } + } + return Result; +} + +//===----------------------------------------------------------------------===// +// Relation Implementation +//===----------------------------------------------------------------------===// + +// contradicts - Return true if the relationship specified by the operand +// contradicts already known information. +// +bool Relation::contradicts(unsigned Op, + const ValueInfo &VI) const { + assert (Op != Instruction::Add && "Invalid relation argument!"); + + // If this is a relationship with a constant, make sure that this relationship + // does not contradict properties known about the bounds of the constant. + // + if (ConstantInt *C = dyn_cast<ConstantInt>(Val)) + if (Op >= ICmpInst::FIRST_ICMP_PREDICATE && + Op <= ICmpInst::LAST_ICMP_PREDICATE) { + ICmpInst::Predicate ipred = ICmpInst::Predicate(Op); + if (ICmpInst::makeConstantRange(ipred, C->getValue()) + .intersectWith(VI.getBounds()).isEmptySet()) + return true; + } + + switch (Rel) { + default: assert(0 && "Unknown Relationship code!"); + case Instruction::Add: return false; // Nothing known, nothing contradicts + case ICmpInst::ICMP_EQ: + return Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_SLT || + Op == ICmpInst::ICMP_UGT || Op == ICmpInst::ICMP_SGT || + Op == ICmpInst::ICMP_NE; + case ICmpInst::ICMP_NE: return Op == ICmpInst::ICMP_EQ; + case ICmpInst::ICMP_ULE: + case ICmpInst::ICMP_SLE: return Op == ICmpInst::ICMP_UGT || + Op == ICmpInst::ICMP_SGT; + case ICmpInst::ICMP_UGE: + case ICmpInst::ICMP_SGE: return Op == ICmpInst::ICMP_ULT || + Op == ICmpInst::ICMP_SLT; + case ICmpInst::ICMP_ULT: + case ICmpInst::ICMP_SLT: + return Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_UGT || + Op == ICmpInst::ICMP_SGT || Op == ICmpInst::ICMP_UGE || + Op == ICmpInst::ICMP_SGE; + case ICmpInst::ICMP_UGT: + case ICmpInst::ICMP_SGT: + return Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_ULT || + Op == ICmpInst::ICMP_SLT || Op == ICmpInst::ICMP_ULE || + Op == ICmpInst::ICMP_SLE; + case FCmpInst::FCMP_OEQ: + return Op == FCmpInst::FCMP_OLT || Op == FCmpInst::FCMP_OGT || + Op == FCmpInst::FCMP_ONE; + case FCmpInst::FCMP_ONE: return Op == FCmpInst::FCMP_OEQ; + case FCmpInst::FCMP_OLE: return Op == FCmpInst::FCMP_OGT; + case FCmpInst::FCMP_OGE: return Op == FCmpInst::FCMP_OLT; + case FCmpInst::FCMP_OLT: + return Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OGT || + Op == FCmpInst::FCMP_OGE; + case FCmpInst::FCMP_OGT: + return Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OLT || + Op == FCmpInst::FCMP_OLE; + } +} + +// incorporate - Incorporate information in the argument into this relation +// entry. This assumes that the information doesn't contradict itself. If any +// new information is gained, true is returned, otherwise false is returned to +// indicate that nothing was updated. +// +bool Relation::incorporate(unsigned Op, ValueInfo &VI) { + assert(!contradicts(Op, VI) && + "Cannot incorporate contradictory information!"); + + // If this is a relationship with a constant, make sure that we update the + // range that is possible for the value to have... + // + if (ConstantInt *C = dyn_cast<ConstantInt>(Val)) + if (Op >= ICmpInst::FIRST_ICMP_PREDICATE && + Op <= ICmpInst::LAST_ICMP_PREDICATE) { + ICmpInst::Predicate ipred = ICmpInst::Predicate(Op); + VI.getBounds() = + ICmpInst::makeConstantRange(ipred, C->getValue()) + .intersectWith(VI.getBounds()); + } + + switch (Rel) { + default: assert(0 && "Unknown prior value!"); + case Instruction::Add: Rel = Op; return true; + case ICmpInst::ICMP_EQ: + case ICmpInst::ICMP_NE: + case ICmpInst::ICMP_ULT: + case ICmpInst::ICMP_SLT: + case ICmpInst::ICMP_UGT: + case ICmpInst::ICMP_SGT: return false; // Nothing is more precise + case ICmpInst::ICMP_ULE: + case ICmpInst::ICMP_SLE: + if (Op == ICmpInst::ICMP_EQ || Op == ICmpInst::ICMP_ULT || + Op == ICmpInst::ICMP_SLT) { + Rel = Op; + return true; + } else if (Op == ICmpInst::ICMP_NE) { + Rel = Rel == ICmpInst::ICMP_ULE ? ICmpInst::ICMP_ULT : + ICmpInst::ICMP_SLT; + return true; + } + return false; + case ICmpInst::ICMP_UGE: + case ICmpInst::ICMP_SGE: + if (Op == ICmpInst::ICMP_EQ || ICmpInst::ICMP_UGT || + Op == ICmpInst::ICMP_SGT) { + Rel = Op; + return true; + } else if (Op == ICmpInst::ICMP_NE) { + Rel = Rel == ICmpInst::ICMP_UGE ? ICmpInst::ICMP_UGT : + ICmpInst::ICMP_SGT; + return true; + } + return false; + case FCmpInst::FCMP_OEQ: return false; // Nothing is more precise + case FCmpInst::FCMP_ONE: return false; // Nothing is more precise + case FCmpInst::FCMP_OLT: return false; // Nothing is more precise + case FCmpInst::FCMP_OGT: return false; // Nothing is more precise + case FCmpInst::FCMP_OLE: + if (Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OLT) { + Rel = Op; + return true; + } else if (Op == FCmpInst::FCMP_ONE) { + Rel = FCmpInst::FCMP_OLT; + return true; + } + return false; + case FCmpInst::FCMP_OGE: + return Op == FCmpInst::FCMP_OLT; + if (Op == FCmpInst::FCMP_OEQ || Op == FCmpInst::FCMP_OGT) { + Rel = Op; + return true; + } else if (Op == FCmpInst::FCMP_ONE) { + Rel = FCmpInst::FCMP_OGT; + return true; + } + return false; + } +} + +// getImpliedResult - If this relationship between two values implies that +// the specified relationship is true or false, return that. If we cannot +// determine the result required, return Unknown. +// +Relation::KnownResult +Relation::getImpliedResult(unsigned Op) const { + if (Rel == Op) return KnownTrue; + if (Op >= ICmpInst::FIRST_ICMP_PREDICATE && + Op <= ICmpInst::LAST_ICMP_PREDICATE) { + if (Rel == unsigned(ICmpInst::getInversePredicate(ICmpInst::Predicate(Op)))) + return KnownFalse; + } else if (Op <= FCmpInst::LAST_FCMP_PREDICATE) { + if (Rel == unsigned(FCmpInst::getInversePredicate(FCmpInst::Predicate(Op)))) + return KnownFalse; + } + + switch (Rel) { + default: assert(0 && "Unknown prior value!"); + case ICmpInst::ICMP_EQ: + if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_SLE || + Op == ICmpInst::ICMP_UGE || Op == ICmpInst::ICMP_SGE) return KnownTrue; + if (Op == ICmpInst::ICMP_ULT || Op == ICmpInst::ICMP_SLT || + Op == ICmpInst::ICMP_UGT || Op == ICmpInst::ICMP_SGT) return KnownFalse; + break; + case ICmpInst::ICMP_ULT: + case ICmpInst::ICMP_SLT: + if (Op == ICmpInst::ICMP_ULE || Op == ICmpInst::ICMP_SLE || + Op == ICmpInst::ICMP_NE) return KnownTrue; + if (Op == ICmpInst::ICMP_EQ) return KnownFalse; + break; + case ICmpInst::ICMP_UGT: + case ICmpInst::ICMP_SGT: + if (Op == ICmpInst::ICMP_UGE || Op == ICmpInst::ICMP_SGE || + Op == ICmpInst::ICMP_NE) return KnownTrue; + if (Op == ICmpInst::ICMP_EQ) return KnownFalse; + break; + case FCmpInst::FCMP_OEQ: + if (Op == FCmpInst::FCMP_OLE || Op == FCmpInst::FCMP_OGE) return KnownTrue; + if (Op == FCmpInst::FCMP_OLT || Op == FCmpInst::FCMP_OGT) return KnownFalse; + break; + case FCmpInst::FCMP_OLT: + if (Op == FCmpInst::FCMP_ONE || Op == FCmpInst::FCMP_OLE) return KnownTrue; + if (Op == FCmpInst::FCMP_OEQ) return KnownFalse; + break; + case FCmpInst::FCMP_OGT: + if (Op == FCmpInst::FCMP_ONE || Op == FCmpInst::FCMP_OGE) return KnownTrue; + if (Op == FCmpInst::FCMP_OEQ) return KnownFalse; + break; + case ICmpInst::ICMP_NE: + case ICmpInst::ICMP_SLE: + case ICmpInst::ICMP_ULE: + case ICmpInst::ICMP_UGE: + case ICmpInst::ICMP_SGE: + case FCmpInst::FCMP_ONE: + case FCmpInst::FCMP_OLE: + case FCmpInst::FCMP_OGE: + case FCmpInst::FCMP_FALSE: + case FCmpInst::FCMP_ORD: + case FCmpInst::FCMP_UNO: + case FCmpInst::FCMP_UEQ: + case FCmpInst::FCMP_UGT: + case FCmpInst::FCMP_UGE: + case FCmpInst::FCMP_ULT: + case FCmpInst::FCMP_ULE: + case FCmpInst::FCMP_UNE: + case FCmpInst::FCMP_TRUE: + break; + } + return Unknown; +} + + +//===----------------------------------------------------------------------===// +// Printing Support... +//===----------------------------------------------------------------------===// + +// print - Implement the standard print form to print out analysis information. +void CEE::print(std::ostream &O, const Module *M) const { + O << "\nPrinting Correlated Expression Info:\n"; + for (std::map<BasicBlock*, RegionInfo>::const_iterator I = + RegionInfoMap.begin(), E = RegionInfoMap.end(); I != E; ++I) + I->second.print(O); +} + +// print - Output information about this region... +void RegionInfo::print(std::ostream &OS) const { + if (ValueMap.empty()) return; + + OS << " RegionInfo for basic block: " << BB->getName() << "\n"; + for (std::map<Value*, ValueInfo>::const_iterator + I = ValueMap.begin(), E = ValueMap.end(); I != E; ++I) + I->second.print(OS, I->first); + OS << "\n"; +} + +// print - Output information about this value relation... +void ValueInfo::print(std::ostream &OS, Value *V) const { + if (Relationships.empty()) return; + + if (V) { + OS << " ValueInfo for: "; + WriteAsOperand(OS, V); + } + OS << "\n Bounds = " << Bounds << "\n"; + if (Replacement) { + OS << " Replacement = "; + WriteAsOperand(OS, Replacement); + OS << "\n"; + } + for (unsigned i = 0, e = Relationships.size(); i != e; ++i) + Relationships[i].print(OS); +} + +// print - Output this relation to the specified stream +void Relation::print(std::ostream &OS) const { + OS << " is "; + switch (Rel) { + default: OS << "*UNKNOWN*"; break; + case ICmpInst::ICMP_EQ: + case FCmpInst::FCMP_ORD: + case FCmpInst::FCMP_UEQ: + case FCmpInst::FCMP_OEQ: OS << "== "; break; + case ICmpInst::ICMP_NE: + case FCmpInst::FCMP_UNO: + case FCmpInst::FCMP_UNE: + case FCmpInst::FCMP_ONE: OS << "!= "; break; + case ICmpInst::ICMP_ULT: + case ICmpInst::ICMP_SLT: + case FCmpInst::FCMP_ULT: + case FCmpInst::FCMP_OLT: OS << "< "; break; + case ICmpInst::ICMP_UGT: + case ICmpInst::ICMP_SGT: + case FCmpInst::FCMP_UGT: + case FCmpInst::FCMP_OGT: OS << "> "; break; + case ICmpInst::ICMP_ULE: + case ICmpInst::ICMP_SLE: + case FCmpInst::FCMP_ULE: + case FCmpInst::FCMP_OLE: OS << "<= "; break; + case ICmpInst::ICMP_UGE: + case ICmpInst::ICMP_SGE: + case FCmpInst::FCMP_UGE: + case FCmpInst::FCMP_OGE: OS << ">= "; break; + } + + WriteAsOperand(OS, Val); + OS << "\n"; +} + +// Don't inline these methods or else we won't be able to call them from GDB! +void Relation::dump() const { print(*cerr.stream()); } +void ValueInfo::dump() const { print(*cerr.stream(), 0); } +void RegionInfo::dump() const { print(*cerr.stream()); } |