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Diffstat (limited to 'lib/Transforms/Scalar/PredicateSimplifier.cpp')
| -rw-r--r-- | lib/Transforms/Scalar/PredicateSimplifier.cpp | 2725 |
1 files changed, 2725 insertions, 0 deletions
diff --git a/lib/Transforms/Scalar/PredicateSimplifier.cpp b/lib/Transforms/Scalar/PredicateSimplifier.cpp new file mode 100644 index 0000000..a7e4d6e --- /dev/null +++ b/lib/Transforms/Scalar/PredicateSimplifier.cpp @@ -0,0 +1,2725 @@ +//===-- PredicateSimplifier.cpp - Path Sensitive Simplifier ---------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// Path-sensitive optimizer. In a branch where x == y, replace uses of +// x with y. Permits further optimization, such as the elimination of +// the unreachable call: +// +// void test(int *p, int *q) +// { +// if (p != q) +// return; +// +// if (*p != *q) +// foo(); // unreachable +// } +// +//===----------------------------------------------------------------------===// +// +// The InequalityGraph focusses on four properties; equals, not equals, +// less-than and less-than-or-equals-to. The greater-than forms are also held +// just to allow walking from a lesser node to a greater one. These properties +// are stored in a lattice; LE can become LT or EQ, NE can become LT or GT. +// +// These relationships define a graph between values of the same type. Each +// Value is stored in a map table that retrieves the associated Node. This +// is how EQ relationships are stored; the map contains pointers from equal +// Value to the same node. The node contains a most canonical Value* form +// and the list of known relationships with other nodes. +// +// If two nodes are known to be inequal, then they will contain pointers to +// each other with an "NE" relationship. If node getNode(%x) is less than +// getNode(%y), then the %x node will contain <%y, GT> and %y will contain +// <%x, LT>. This allows us to tie nodes together into a graph like this: +// +// %a < %b < %c < %d +// +// with four nodes representing the properties. The InequalityGraph provides +// querying with "isRelatedBy" and mutators "addEquality" and "addInequality". +// To find a relationship, we start with one of the nodes any binary search +// through its list to find where the relationships with the second node start. +// Then we iterate through those to find the first relationship that dominates +// our context node. +// +// To create these properties, we wait until a branch or switch instruction +// implies that a particular value is true (or false). The VRPSolver is +// responsible for analyzing the variable and seeing what new inferences +// can be made from each property. For example: +// +// %P = icmp ne i32* %ptr, null +// %a = and i1 %P, %Q +// br i1 %a label %cond_true, label %cond_false +// +// For the true branch, the VRPSolver will start with %a EQ true and look at +// the definition of %a and find that it can infer that %P and %Q are both +// true. From %P being true, it can infer that %ptr NE null. For the false +// branch it can't infer anything from the "and" instruction. +// +// Besides branches, we can also infer properties from instruction that may +// have undefined behaviour in certain cases. For example, the dividend of +// a division may never be zero. After the division instruction, we may assume +// that the dividend is not equal to zero. +// +//===----------------------------------------------------------------------===// +// +// The ValueRanges class stores the known integer bounds of a Value. When we +// encounter i8 %a u< %b, the ValueRanges stores that %a = [1, 255] and +// %b = [0, 254]. +// +// It never stores an empty range, because that means that the code is +// unreachable. It never stores a single-element range since that's an equality +// relationship and better stored in the InequalityGraph, nor an empty range +// since that is better stored in UnreachableBlocks. +// +//===----------------------------------------------------------------------===// + +#define DEBUG_TYPE "predsimplify" +#include "llvm/Transforms/Scalar.h" +#include "llvm/Constants.h" +#include "llvm/DerivedTypes.h" +#include "llvm/Instructions.h" +#include "llvm/Pass.h" +#include "llvm/ADT/DepthFirstIterator.h" +#include "llvm/ADT/SetOperations.h" +#include "llvm/ADT/SetVector.h" +#include "llvm/ADT/Statistic.h" +#include "llvm/ADT/STLExtras.h" +#include "llvm/Analysis/Dominators.h" +#include "llvm/Assembly/Writer.h" +#include "llvm/Support/CFG.h" +#include "llvm/Support/Compiler.h" +#include "llvm/Support/ConstantRange.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/InstVisitor.h" +#include "llvm/Target/TargetData.h" +#include "llvm/Transforms/Utils/Local.h" +#include <algorithm> +#include <deque> +#include <stack> +using namespace llvm; + +STATISTIC(NumVarsReplaced, "Number of argument substitutions"); +STATISTIC(NumInstruction , "Number of instructions removed"); +STATISTIC(NumSimple , "Number of simple replacements"); +STATISTIC(NumBlocks , "Number of blocks marked unreachable"); +STATISTIC(NumSnuggle , "Number of comparisons snuggled"); + +namespace { + class DomTreeDFS { + public: + class Node { + friend class DomTreeDFS; + public: + typedef std::vector<Node *>::iterator iterator; + typedef std::vector<Node *>::const_iterator const_iterator; + + unsigned getDFSNumIn() const { return DFSin; } + unsigned getDFSNumOut() const { return DFSout; } + + BasicBlock *getBlock() const { return BB; } + + iterator begin() { return Children.begin(); } + iterator end() { return Children.end(); } + + const_iterator begin() const { return Children.begin(); } + const_iterator end() const { return Children.end(); } + + bool dominates(const Node *N) const { + return DFSin <= N->DFSin && DFSout >= N->DFSout; + } + + bool DominatedBy(const Node *N) const { + return N->dominates(this); + } + + /// Sorts by the number of descendants. With this, you can iterate + /// through a sorted list and the first matching entry is the most + /// specific match for your basic block. The order provided is stable; + /// DomTreeDFS::Nodes with the same number of descendants are sorted by + /// DFS in number. + bool operator<(const Node &N) const { + unsigned spread = DFSout - DFSin; + unsigned N_spread = N.DFSout - N.DFSin; + if (spread == N_spread) return DFSin < N.DFSin; + return spread < N_spread; + } + bool operator>(const Node &N) const { return N < *this; } + + private: + unsigned DFSin, DFSout; + BasicBlock *BB; + + std::vector<Node *> Children; + }; + + // XXX: this may be slow. Instead of using "new" for each node, consider + // putting them in a vector to keep them contiguous. + explicit DomTreeDFS(DominatorTree *DT) { + std::stack<std::pair<Node *, DomTreeNode *> > S; + + Entry = new Node; + Entry->BB = DT->getRootNode()->getBlock(); + S.push(std::make_pair(Entry, DT->getRootNode())); + + NodeMap[Entry->BB] = Entry; + + while (!S.empty()) { + std::pair<Node *, DomTreeNode *> &Pair = S.top(); + Node *N = Pair.first; + DomTreeNode *DTNode = Pair.second; + S.pop(); + + for (DomTreeNode::iterator I = DTNode->begin(), E = DTNode->end(); + I != E; ++I) { + Node *NewNode = new Node; + NewNode->BB = (*I)->getBlock(); + N->Children.push_back(NewNode); + S.push(std::make_pair(NewNode, *I)); + + NodeMap[NewNode->BB] = NewNode; + } + } + + renumber(); + +#ifndef NDEBUG + DEBUG(dump()); +#endif + } + +#ifndef NDEBUG + virtual +#endif + ~DomTreeDFS() { + std::stack<Node *> S; + + S.push(Entry); + while (!S.empty()) { + Node *N = S.top(); S.pop(); + + for (Node::iterator I = N->begin(), E = N->end(); I != E; ++I) + S.push(*I); + + delete N; + } + } + + /// getRootNode - This returns the entry node for the CFG of the function. + Node *getRootNode() const { return Entry; } + + /// getNodeForBlock - return the node for the specified basic block. + Node *getNodeForBlock(BasicBlock *BB) const { + if (!NodeMap.count(BB)) return 0; + return const_cast<DomTreeDFS*>(this)->NodeMap[BB]; + } + + /// dominates - returns true if the basic block for I1 dominates that of + /// the basic block for I2. If the instructions belong to the same basic + /// block, the instruction first instruction sequentially in the block is + /// considered dominating. + bool dominates(Instruction *I1, Instruction *I2) { + BasicBlock *BB1 = I1->getParent(), + *BB2 = I2->getParent(); + if (BB1 == BB2) { + if (isa<TerminatorInst>(I1)) return false; + if (isa<TerminatorInst>(I2)) return true; + if ( isa<PHINode>(I1) && !isa<PHINode>(I2)) return true; + if (!isa<PHINode>(I1) && isa<PHINode>(I2)) return false; + + for (BasicBlock::const_iterator I = BB2->begin(), E = BB2->end(); + I != E; ++I) { + if (&*I == I1) return true; + else if (&*I == I2) return false; + } + assert(!"Instructions not found in parent BasicBlock?"); + } else { + Node *Node1 = getNodeForBlock(BB1), + *Node2 = getNodeForBlock(BB2); + return Node1 && Node2 && Node1->dominates(Node2); + } + return false; // Not reached + } + + private: + /// renumber - calculates the depth first search numberings and applies + /// them onto the nodes. + void renumber() { + std::stack<std::pair<Node *, Node::iterator> > S; + unsigned n = 0; + + Entry->DFSin = ++n; + S.push(std::make_pair(Entry, Entry->begin())); + + while (!S.empty()) { + std::pair<Node *, Node::iterator> &Pair = S.top(); + Node *N = Pair.first; + Node::iterator &I = Pair.second; + + if (I == N->end()) { + N->DFSout = ++n; + S.pop(); + } else { + Node *Next = *I++; + Next->DFSin = ++n; + S.push(std::make_pair(Next, Next->begin())); + } + } + } + +#ifndef NDEBUG + virtual void dump() const { + dump(*cerr.stream()); + } + + void dump(std::ostream &os) const { + os << "Predicate simplifier DomTreeDFS: \n"; + dump(Entry, 0, os); + os << "\n\n"; + } + + void dump(Node *N, int depth, std::ostream &os) const { + ++depth; + for (int i = 0; i < depth; ++i) { os << " "; } + os << "[" << depth << "] "; + + os << N->getBlock()->getName() << " (" << N->getDFSNumIn() + << ", " << N->getDFSNumOut() << ")\n"; + + for (Node::iterator I = N->begin(), E = N->end(); I != E; ++I) + dump(*I, depth, os); + } +#endif + + Node *Entry; + std::map<BasicBlock *, Node *> NodeMap; + }; + + // SLT SGT ULT UGT EQ + // 0 1 0 1 0 -- GT 10 + // 0 1 0 1 1 -- GE 11 + // 0 1 1 0 0 -- SGTULT 12 + // 0 1 1 0 1 -- SGEULE 13 + // 0 1 1 1 0 -- SGT 14 + // 0 1 1 1 1 -- SGE 15 + // 1 0 0 1 0 -- SLTUGT 18 + // 1 0 0 1 1 -- SLEUGE 19 + // 1 0 1 0 0 -- LT 20 + // 1 0 1 0 1 -- LE 21 + // 1 0 1 1 0 -- SLT 22 + // 1 0 1 1 1 -- SLE 23 + // 1 1 0 1 0 -- UGT 26 + // 1 1 0 1 1 -- UGE 27 + // 1 1 1 0 0 -- ULT 28 + // 1 1 1 0 1 -- ULE 29 + // 1 1 1 1 0 -- NE 30 + enum LatticeBits { + EQ_BIT = 1, UGT_BIT = 2, ULT_BIT = 4, SGT_BIT = 8, SLT_BIT = 16 + }; + enum LatticeVal { + GT = SGT_BIT | UGT_BIT, + GE = GT | EQ_BIT, + LT = SLT_BIT | ULT_BIT, + LE = LT | EQ_BIT, + NE = SLT_BIT | SGT_BIT | ULT_BIT | UGT_BIT, + SGTULT = SGT_BIT | ULT_BIT, + SGEULE = SGTULT | EQ_BIT, + SLTUGT = SLT_BIT | UGT_BIT, + SLEUGE = SLTUGT | EQ_BIT, + ULT = SLT_BIT | SGT_BIT | ULT_BIT, + UGT = SLT_BIT | SGT_BIT | UGT_BIT, + SLT = SLT_BIT | ULT_BIT | UGT_BIT, + SGT = SGT_BIT | ULT_BIT | UGT_BIT, + SLE = SLT | EQ_BIT, + SGE = SGT | EQ_BIT, + ULE = ULT | EQ_BIT, + UGE = UGT | EQ_BIT + }; + +#ifndef NDEBUG + /// validPredicate - determines whether a given value is actually a lattice + /// value. Only used in assertions or debugging. + static bool validPredicate(LatticeVal LV) { + switch (LV) { + case GT: case GE: case LT: case LE: case NE: + case SGTULT: case SGT: case SGEULE: + case SLTUGT: case SLT: case SLEUGE: + case ULT: case UGT: + case SLE: case SGE: case ULE: case UGE: + return true; + default: + return false; + } + } +#endif + + /// reversePredicate - reverse the direction of the inequality + static LatticeVal reversePredicate(LatticeVal LV) { + unsigned reverse = LV ^ (SLT_BIT|SGT_BIT|ULT_BIT|UGT_BIT); //preserve EQ_BIT + + if ((reverse & (SLT_BIT|SGT_BIT)) == 0) + reverse |= (SLT_BIT|SGT_BIT); + + if ((reverse & (ULT_BIT|UGT_BIT)) == 0) + reverse |= (ULT_BIT|UGT_BIT); + + LatticeVal Rev = static_cast<LatticeVal>(reverse); + assert(validPredicate(Rev) && "Failed reversing predicate."); + return Rev; + } + + /// ValueNumbering stores the scope-specific value numbers for a given Value. + class VISIBILITY_HIDDEN ValueNumbering { + + /// VNPair is a tuple of {Value, index number, DomTreeDFS::Node}. It + /// includes the comparison operators necessary to allow you to store it + /// in a sorted vector. + class VISIBILITY_HIDDEN VNPair { + public: + Value *V; + unsigned index; + DomTreeDFS::Node *Subtree; + + VNPair(Value *V, unsigned index, DomTreeDFS::Node *Subtree) + : V(V), index(index), Subtree(Subtree) {} + + bool operator==(const VNPair &RHS) const { + return V == RHS.V && Subtree == RHS.Subtree; + } + + bool operator<(const VNPair &RHS) const { + if (V != RHS.V) return V < RHS.V; + return *Subtree < *RHS.Subtree; + } + + bool operator<(Value *RHS) const { + return V < RHS; + } + + bool operator>(Value *RHS) const { + return V > RHS; + } + + friend bool operator<(Value *RHS, const VNPair &pair) { + return pair.operator>(RHS); + } + }; + + typedef std::vector<VNPair> VNMapType; + VNMapType VNMap; + + /// The canonical choice for value number at index. + std::vector<Value *> Values; + + DomTreeDFS *DTDFS; + + public: +#ifndef NDEBUG + virtual ~ValueNumbering() {} + virtual void dump() { + dump(*cerr.stream()); + } + + void dump(std::ostream &os) { + for (unsigned i = 1; i <= Values.size(); ++i) { + os << i << " = "; + WriteAsOperand(os, Values[i-1]); + os << " {"; + for (unsigned j = 0; j < VNMap.size(); ++j) { + if (VNMap[j].index == i) { + WriteAsOperand(os, VNMap[j].V); + os << " (" << VNMap[j].Subtree->getDFSNumIn() << ") "; + } + } + os << "}\n"; + } + } +#endif + + /// compare - returns true if V1 is a better canonical value than V2. + bool compare(Value *V1, Value *V2) const { + if (isa<Constant>(V1)) + return !isa<Constant>(V2); + else if (isa<Constant>(V2)) + return false; + else if (isa<Argument>(V1)) + return !isa<Argument>(V2); + else if (isa<Argument>(V2)) + return false; + + Instruction *I1 = dyn_cast<Instruction>(V1); + Instruction *I2 = dyn_cast<Instruction>(V2); + + if (!I1 || !I2) + return V1->getNumUses() < V2->getNumUses(); + + return DTDFS->dominates(I1, I2); + } + + ValueNumbering(DomTreeDFS *DTDFS) : DTDFS(DTDFS) {} + + /// valueNumber - finds the value number for V under the Subtree. If + /// there is no value number, returns zero. + unsigned valueNumber(Value *V, DomTreeDFS::Node *Subtree) { + if (!(isa<Constant>(V) || isa<Argument>(V) || isa<Instruction>(V)) + || V->getType() == Type::VoidTy) return 0; + + VNMapType::iterator E = VNMap.end(); + VNPair pair(V, 0, Subtree); + VNMapType::iterator I = std::lower_bound(VNMap.begin(), E, pair); + while (I != E && I->V == V) { + if (I->Subtree->dominates(Subtree)) + return I->index; + ++I; + } + return 0; + } + + /// getOrInsertVN - always returns a value number, creating it if necessary. + unsigned getOrInsertVN(Value *V, DomTreeDFS::Node *Subtree) { + if (unsigned n = valueNumber(V, Subtree)) + return n; + else + return newVN(V); + } + + /// newVN - creates a new value number. Value V must not already have a + /// value number assigned. + unsigned newVN(Value *V) { + assert((isa<Constant>(V) || isa<Argument>(V) || isa<Instruction>(V)) && + "Bad Value for value numbering."); + assert(V->getType() != Type::VoidTy && "Won't value number a void value"); + + Values.push_back(V); + + VNPair pair = VNPair(V, Values.size(), DTDFS->getRootNode()); + VNMapType::iterator I = std::lower_bound(VNMap.begin(), VNMap.end(), pair); + assert((I == VNMap.end() || value(I->index) != V) && + "Attempt to create a duplicate value number."); + VNMap.insert(I, pair); + + return Values.size(); + } + + /// value - returns the Value associated with a value number. + Value *value(unsigned index) const { + assert(index != 0 && "Zero index is reserved for not found."); + assert(index <= Values.size() && "Index out of range."); + return Values[index-1]; + } + + /// canonicalize - return a Value that is equal to V under Subtree. + Value *canonicalize(Value *V, DomTreeDFS::Node *Subtree) { + if (isa<Constant>(V)) return V; + + if (unsigned n = valueNumber(V, Subtree)) + return value(n); + else + return V; + } + + /// addEquality - adds that value V belongs to the set of equivalent + /// values defined by value number n under Subtree. + void addEquality(unsigned n, Value *V, DomTreeDFS::Node *Subtree) { + assert(canonicalize(value(n), Subtree) == value(n) && + "Node's 'canonical' choice isn't best within this subtree."); + + // Suppose that we are given "%x -> node #1 (%y)". The problem is that + // we may already have "%z -> node #2 (%x)" somewhere above us in the + // graph. We need to find those edges and add "%z -> node #1 (%y)" + // to keep the lookups canonical. + + std::vector<Value *> ToRepoint(1, V); + + if (unsigned Conflict = valueNumber(V, Subtree)) { + for (VNMapType::iterator I = VNMap.begin(), E = VNMap.end(); + I != E; ++I) { + if (I->index == Conflict && I->Subtree->dominates(Subtree)) + ToRepoint.push_back(I->V); + } + } + + for (std::vector<Value *>::iterator VI = ToRepoint.begin(), + VE = ToRepoint.end(); VI != VE; ++VI) { + Value *V = *VI; + + VNPair pair(V, n, Subtree); + VNMapType::iterator B = VNMap.begin(), E = VNMap.end(); + VNMapType::iterator I = std::lower_bound(B, E, pair); + if (I != E && I->V == V && I->Subtree == Subtree) + I->index = n; // Update best choice + else + VNMap.insert(I, pair); // New Value + + // XXX: we currently don't have to worry about updating values with + // more specific Subtrees, but we will need to for PHI node support. + +#ifndef NDEBUG + Value *V_n = value(n); + if (isa<Constant>(V) && isa<Constant>(V_n)) { + assert(V == V_n && "Constant equals different constant?"); + } +#endif + } + } + + /// remove - removes all references to value V. + void remove(Value *V) { + VNMapType::iterator B = VNMap.begin(), E = VNMap.end(); + VNPair pair(V, 0, DTDFS->getRootNode()); + VNMapType::iterator J = std::upper_bound(B, E, pair); + VNMapType::iterator I = J; + + while (I != B && (I == E || I->V == V)) --I; + + VNMap.erase(I, J); + } + }; + + /// The InequalityGraph stores the relationships between values. + /// Each Value in the graph is assigned to a Node. Nodes are pointer + /// comparable for equality. The caller is expected to maintain the logical + /// consistency of the system. + /// + /// The InequalityGraph class may invalidate Node*s after any mutator call. + /// @brief The InequalityGraph stores the relationships between values. + class VISIBILITY_HIDDEN InequalityGraph { + ValueNumbering &VN; + DomTreeDFS::Node *TreeRoot; + + InequalityGraph(); // DO NOT IMPLEMENT + InequalityGraph(InequalityGraph &); // DO NOT IMPLEMENT + public: + InequalityGraph(ValueNumbering &VN, DomTreeDFS::Node *TreeRoot) + : VN(VN), TreeRoot(TreeRoot) {} + + class Node; + + /// An Edge is contained inside a Node making one end of the edge implicit + /// and contains a pointer to the other end. The edge contains a lattice + /// value specifying the relationship and an DomTreeDFS::Node specifying + /// the root in the dominator tree to which this edge applies. + class VISIBILITY_HIDDEN Edge { + public: + Edge(unsigned T, LatticeVal V, DomTreeDFS::Node *ST) + : To(T), LV(V), Subtree(ST) {} + + unsigned To; + LatticeVal LV; + DomTreeDFS::Node *Subtree; + + bool operator<(const Edge &edge) const { + if (To != edge.To) return To < edge.To; + return *Subtree < *edge.Subtree; + } + + bool operator<(unsigned to) const { + return To < to; + } + + bool operator>(unsigned to) const { + return To > to; + } + + friend bool operator<(unsigned to, const Edge &edge) { + return edge.operator>(to); + } + }; + + /// A single node in the InequalityGraph. This stores the canonical Value + /// for the node, as well as the relationships with the neighbours. + /// + /// @brief A single node in the InequalityGraph. + class VISIBILITY_HIDDEN Node { + friend class InequalityGraph; + + typedef SmallVector<Edge, 4> RelationsType; + RelationsType Relations; + + // TODO: can this idea improve performance? + //friend class std::vector<Node>; + //Node(Node &N) { RelationsType.swap(N.RelationsType); } + + public: + typedef RelationsType::iterator iterator; + typedef RelationsType::const_iterator const_iterator; + +#ifndef NDEBUG + virtual ~Node() {} + virtual void dump() const { + dump(*cerr.stream()); + } + private: + void dump(std::ostream &os) const { + static const std::string names[32] = + { "000000", "000001", "000002", "000003", "000004", "000005", + "000006", "000007", "000008", "000009", " >", " >=", + " s>u<", "s>=u<=", " s>", " s>=", "000016", "000017", + " s<u>", "s<=u>=", " <", " <=", " s<", " s<=", + "000024", "000025", " u>", " u>=", " u<", " u<=", + " !=", "000031" }; + for (Node::const_iterator NI = begin(), NE = end(); NI != NE; ++NI) { + os << names[NI->LV] << " " << NI->To + << " (" << NI->Subtree->getDFSNumIn() << "), "; + } + } + public: +#endif + + iterator begin() { return Relations.begin(); } + iterator end() { return Relations.end(); } + const_iterator begin() const { return Relations.begin(); } + const_iterator end() const { return Relations.end(); } + + iterator find(unsigned n, DomTreeDFS::Node *Subtree) { + iterator E = end(); + for (iterator I = std::lower_bound(begin(), E, n); + I != E && I->To == n; ++I) { + if (Subtree->DominatedBy(I->Subtree)) + return I; + } + return E; + } + + const_iterator find(unsigned n, DomTreeDFS::Node *Subtree) const { + const_iterator E = end(); + for (const_iterator I = std::lower_bound(begin(), E, n); + I != E && I->To == n; ++I) { + if (Subtree->DominatedBy(I->Subtree)) + return I; + } + return E; + } + + /// update - updates the lattice value for a given node, creating a new + /// entry if one doesn't exist. The new lattice value must not be + /// inconsistent with any previously existing value. + void update(unsigned n, LatticeVal R, DomTreeDFS::Node *Subtree) { + assert(validPredicate(R) && "Invalid predicate."); + + Edge edge(n, R, Subtree); + iterator B = begin(), E = end(); + iterator I = std::lower_bound(B, E, edge); + + iterator J = I; + while (J != E && J->To == n) { + if (Subtree->DominatedBy(J->Subtree)) + break; + ++J; + } + + if (J != E && J->To == n) { + edge.LV = static_cast<LatticeVal>(J->LV & R); + assert(validPredicate(edge.LV) && "Invalid union of lattice values."); + + if (edge.LV == J->LV) + return; // This update adds nothing new. + } + + if (I != B) { + // We also have to tighten any edge beneath our update. + for (iterator K = I - 1; K->To == n; --K) { + if (K->Subtree->DominatedBy(Subtree)) { + LatticeVal LV = static_cast<LatticeVal>(K->LV & edge.LV); + assert(validPredicate(LV) && "Invalid union of lattice values"); + K->LV = LV; + } + if (K == B) break; + } + } + + // Insert new edge at Subtree if it isn't already there. + if (I == E || I->To != n || Subtree != I->Subtree) + Relations.insert(I, edge); + } + }; + + private: + + std::vector<Node> Nodes; + + public: + /// node - returns the node object at a given value number. The pointer + /// returned may be invalidated on the next call to node(). + Node *node(unsigned index) { + assert(VN.value(index)); // This triggers the necessary checks. + if (Nodes.size() < index) Nodes.resize(index); + return &Nodes[index-1]; + } + + /// isRelatedBy - true iff n1 op n2 + bool isRelatedBy(unsigned n1, unsigned n2, DomTreeDFS::Node *Subtree, + LatticeVal LV) { + if (n1 == n2) return LV & EQ_BIT; + + Node *N1 = node(n1); + Node::iterator I = N1->find(n2, Subtree), E = N1->end(); + if (I != E) return (I->LV & LV) == I->LV; + + return false; + } + + // The add* methods assume that your input is logically valid and may + // assertion-fail or infinitely loop if you attempt a contradiction. + + /// addInequality - Sets n1 op n2. + /// It is also an error to call this on an inequality that is already true. + void addInequality(unsigned n1, unsigned n2, DomTreeDFS::Node *Subtree, + LatticeVal LV1) { + assert(n1 != n2 && "A node can't be inequal to itself."); + + if (LV1 != NE) + assert(!isRelatedBy(n1, n2, Subtree, reversePredicate(LV1)) && + "Contradictory inequality."); + + // Suppose we're adding %n1 < %n2. Find all the %a < %n1 and + // add %a < %n2 too. This keeps the graph fully connected. + if (LV1 != NE) { + // Break up the relationship into signed and unsigned comparison parts. + // If the signed parts of %a op1 %n1 match that of %n1 op2 %n2, and + // op1 and op2 aren't NE, then add %a op3 %n2. The new relationship + // should have the EQ_BIT iff it's set for both op1 and op2. + + unsigned LV1_s = LV1 & (SLT_BIT|SGT_BIT); + unsigned LV1_u = LV1 & (ULT_BIT|UGT_BIT); + + for (Node::iterator I = node(n1)->begin(), E = node(n1)->end(); I != E; ++I) { + if (I->LV != NE && I->To != n2) { + + DomTreeDFS::Node *Local_Subtree = NULL; + if (Subtree->DominatedBy(I->Subtree)) + Local_Subtree = Subtree; + else if (I->Subtree->DominatedBy(Subtree)) + Local_Subtree = I->Subtree; + + if (Local_Subtree) { + unsigned new_relationship = 0; + LatticeVal ILV = reversePredicate(I->LV); + unsigned ILV_s = ILV & (SLT_BIT|SGT_BIT); + unsigned ILV_u = ILV & (ULT_BIT|UGT_BIT); + + if (LV1_s != (SLT_BIT|SGT_BIT) && ILV_s == LV1_s) + new_relationship |= ILV_s; + if (LV1_u != (ULT_BIT|UGT_BIT) && ILV_u == LV1_u) + new_relationship |= ILV_u; + + if (new_relationship) { + if ((new_relationship & (SLT_BIT|SGT_BIT)) == 0) + new_relationship |= (SLT_BIT|SGT_BIT); + if ((new_relationship & (ULT_BIT|UGT_BIT)) == 0) + new_relationship |= (ULT_BIT|UGT_BIT); + if ((LV1 & EQ_BIT) && (ILV & EQ_BIT)) + new_relationship |= EQ_BIT; + + LatticeVal NewLV = static_cast<LatticeVal>(new_relationship); + + node(I->To)->update(n2, NewLV, Local_Subtree); + node(n2)->update(I->To, reversePredicate(NewLV), Local_Subtree); + } + } + } + } + + for (Node::iterator I = node(n2)->begin(), E = node(n2)->end(); I != E; ++I) { + if (I->LV != NE && I->To != n1) { + DomTreeDFS::Node *Local_Subtree = NULL; + if (Subtree->DominatedBy(I->Subtree)) + Local_Subtree = Subtree; + else if (I->Subtree->DominatedBy(Subtree)) + Local_Subtree = I->Subtree; + + if (Local_Subtree) { + unsigned new_relationship = 0; + unsigned ILV_s = I->LV & (SLT_BIT|SGT_BIT); + unsigned ILV_u = I->LV & (ULT_BIT|UGT_BIT); + + if (LV1_s != (SLT_BIT|SGT_BIT) && ILV_s == LV1_s) + new_relationship |= ILV_s; + + if (LV1_u != (ULT_BIT|UGT_BIT) && ILV_u == LV1_u) + new_relationship |= ILV_u; + + if (new_relationship) { + if ((new_relationship & (SLT_BIT|SGT_BIT)) == 0) + new_relationship |= (SLT_BIT|SGT_BIT); + if ((new_relationship & (ULT_BIT|UGT_BIT)) == 0) + new_relationship |= (ULT_BIT|UGT_BIT); + if ((LV1 & EQ_BIT) && (I->LV & EQ_BIT)) + new_relationship |= EQ_BIT; + + LatticeVal NewLV = static_cast<LatticeVal>(new_relationship); + + node(n1)->update(I->To, NewLV, Local_Subtree); + node(I->To)->update(n1, reversePredicate(NewLV), Local_Subtree); + } + } + } + } + } + + node(n1)->update(n2, LV1, Subtree); + node(n2)->update(n1, reversePredicate(LV1), Subtree); + } + + /// remove - removes a node from the graph by removing all references to + /// and from it. + void remove(unsigned n) { + Node *N = node(n); + for (Node::iterator NI = N->begin(), NE = N->end(); NI != NE; ++NI) { + Node::iterator Iter = node(NI->To)->find(n, TreeRoot); + do { + node(NI->To)->Relations.erase(Iter); + Iter = node(NI->To)->find(n, TreeRoot); + } while (Iter != node(NI->To)->end()); + } + N->Relations.clear(); + } + +#ifndef NDEBUG + virtual ~InequalityGraph() {} + virtual void dump() { + dump(*cerr.stream()); + } + + void dump(std::ostream &os) { + for (unsigned i = 1; i <= Nodes.size(); ++i) { + os << i << " = {"; + node(i)->dump(os); + os << "}\n"; + } + } +#endif + }; + + class VRPSolver; + + /// ValueRanges tracks the known integer ranges and anti-ranges of the nodes + /// in the InequalityGraph. + class VISIBILITY_HIDDEN ValueRanges { + ValueNumbering &VN; + TargetData *TD; + + class VISIBILITY_HIDDEN ScopedRange { + typedef std::vector<std::pair<DomTreeDFS::Node *, ConstantRange> > + RangeListType; + RangeListType RangeList; + + static bool swo(const std::pair<DomTreeDFS::Node *, ConstantRange> &LHS, + const std::pair<DomTreeDFS::Node *, ConstantRange> &RHS) { + return *LHS.first < *RHS.first; + } + + public: +#ifndef NDEBUG + virtual ~ScopedRange() {} + virtual void dump() const { + dump(*cerr.stream()); + } + + void dump(std::ostream &os) const { + os << "{"; + for (const_iterator I = begin(), E = end(); I != E; ++I) { + os << &I->second << " (" << I->first->getDFSNumIn() << "), "; + } + os << "}"; + } +#endif + + typedef RangeListType::iterator iterator; + typedef RangeListType::const_iterator const_iterator; + + iterator begin() { return RangeList.begin(); } + iterator end() { return RangeList.end(); } + const_iterator begin() const { return RangeList.begin(); } + const_iterator end() const { return RangeList.end(); } + + iterator find(DomTreeDFS::Node *Subtree) { + static ConstantRange empty(1, false); + iterator E = end(); + iterator I = std::lower_bound(begin(), E, + std::make_pair(Subtree, empty), swo); + + while (I != E && !I->first->dominates(Subtree)) ++I; + return I; + } + + const_iterator find(DomTreeDFS::Node *Subtree) const { + static const ConstantRange empty(1, false); + const_iterator E = end(); + const_iterator I = std::lower_bound(begin(), E, + std::make_pair(Subtree, empty), swo); + + while (I != E && !I->first->dominates(Subtree)) ++I; + return I; + } + + void update(const ConstantRange &CR, DomTreeDFS::Node *Subtree) { + assert(!CR.isEmptySet() && "Empty ConstantRange."); + assert(!CR.isSingleElement() && "Refusing to store single element."); + + static ConstantRange empty(1, false); + iterator E = end(); + iterator I = + std::lower_bound(begin(), E, std::make_pair(Subtree, empty), swo); + + if (I != end() && I->first == Subtree) { + ConstantRange CR2 = I->second.maximalIntersectWith(CR); + assert(!CR2.isEmptySet() && !CR2.isSingleElement() && + "Invalid union of ranges."); + I->second = CR2; + } else + RangeList.insert(I, std::make_pair(Subtree, CR)); + } + }; + + std::vector<ScopedRange> Ranges; + + void update(unsigned n, const ConstantRange &CR, DomTreeDFS::Node *Subtree){ + if (CR.isFullSet()) return; + if (Ranges.size() < n) Ranges.resize(n); + Ranges[n-1].update(CR, Subtree); + } + + /// create - Creates a ConstantRange that matches the given LatticeVal + /// relation with a given integer. + ConstantRange create(LatticeVal LV, const ConstantRange &CR) { + assert(!CR.isEmptySet() && "Can't deal with empty set."); + + if (LV == NE) + return makeConstantRange(ICmpInst::ICMP_NE, CR); + + unsigned LV_s = LV & (SGT_BIT|SLT_BIT); + unsigned LV_u = LV & (UGT_BIT|ULT_BIT); + bool hasEQ = LV & EQ_BIT; + + ConstantRange Range(CR.getBitWidth()); + + if (LV_s == SGT_BIT) { + Range = Range.maximalIntersectWith(makeConstantRange( + hasEQ ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_SGT, CR)); + } else if (LV_s == SLT_BIT) { + Range = Range.maximalIntersectWith(makeConstantRange( + hasEQ ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_SLT, CR)); + } + + if (LV_u == UGT_BIT) { + Range = Range.maximalIntersectWith(makeConstantRange( + hasEQ ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_UGT, CR)); + } else if (LV_u == ULT_BIT) { + Range = Range.maximalIntersectWith(makeConstantRange( + hasEQ ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_ULT, CR)); + } + + return Range; + } + + /// makeConstantRange - Creates a ConstantRange representing the set of all + /// value that match the ICmpInst::Predicate with any of the values in CR. + ConstantRange makeConstantRange(ICmpInst::Predicate ICmpOpcode, + const ConstantRange &CR) { + uint32_t W = CR.getBitWidth(); + switch (ICmpOpcode) { + default: assert(!"Invalid ICmp opcode to makeConstantRange()"); + case ICmpInst::ICMP_EQ: + return ConstantRange(CR.getLower(), CR.getUpper()); + case ICmpInst::ICMP_NE: + if (CR.isSingleElement()) + return ConstantRange(CR.getUpper(), CR.getLower()); + return ConstantRange(W); + case ICmpInst::ICMP_ULT: + return ConstantRange(APInt::getMinValue(W), CR.getUnsignedMax()); + case ICmpInst::ICMP_SLT: + return ConstantRange(APInt::getSignedMinValue(W), CR.getSignedMax()); + case ICmpInst::ICMP_ULE: { + APInt UMax(CR.getUnsignedMax()); + if (UMax.isMaxValue()) + return ConstantRange(W); + return ConstantRange(APInt::getMinValue(W), UMax + 1); + } + case ICmpInst::ICMP_SLE: { + APInt SMax(CR.getSignedMax()); + if (SMax.isMaxSignedValue() || (SMax+1).isMaxSignedValue()) + return ConstantRange(W); + return ConstantRange(APInt::getSignedMinValue(W), SMax + 1); + } + case ICmpInst::ICMP_UGT: + return ConstantRange(CR.getUnsignedMin() + 1, APInt::getNullValue(W)); + case ICmpInst::ICMP_SGT: + return ConstantRange(CR.getSignedMin() + 1, + APInt::getSignedMinValue(W)); + case ICmpInst::ICMP_UGE: { + APInt UMin(CR.getUnsignedMin()); + if (UMin.isMinValue()) + return ConstantRange(W); + return ConstantRange(UMin, APInt::getNullValue(W)); + } + case ICmpInst::ICMP_SGE: { + APInt SMin(CR.getSignedMin()); + if (SMin.isMinSignedValue()) + return ConstantRange(W); + return ConstantRange(SMin, APInt::getSignedMinValue(W)); + } + } + } + +#ifndef NDEBUG + bool isCanonical(Value *V, DomTreeDFS::Node *Subtree) { + return V == VN.canonicalize(V, Subtree); + } +#endif + + public: + + ValueRanges(ValueNumbering &VN, TargetData *TD) : VN(VN), TD(TD) {} + +#ifndef NDEBUG + virtual ~ValueRanges() {} + + virtual void dump() const { + dump(*cerr.stream()); + } + + void dump(std::ostream &os) const { + for (unsigned i = 0, e = Ranges.size(); i != e; ++i) { + os << (i+1) << " = "; + Ranges[i].dump(os); + os << "\n"; + } + } +#endif + + /// range - looks up the ConstantRange associated with a value number. + ConstantRange range(unsigned n, DomTreeDFS::Node *Subtree) { + assert(VN.value(n)); // performs range checks + + if (n <= Ranges.size()) { + ScopedRange::iterator I = Ranges[n-1].find(Subtree); + if (I != Ranges[n-1].end()) return I->second; + } + + Value *V = VN.value(n); + ConstantRange CR = range(V); + return CR; + } + + /// range - determine a range from a Value without performing any lookups. + ConstantRange range(Value *V) const { + if (ConstantInt *C = dyn_cast<ConstantInt>(V)) + return ConstantRange(C->getValue()); + else if (isa<ConstantPointerNull>(V)) + return ConstantRange(APInt::getNullValue(typeToWidth(V->getType()))); + else + return ConstantRange(typeToWidth(V->getType())); + } + + // typeToWidth - returns the number of bits necessary to store a value of + // this type, or zero if unknown. + uint32_t typeToWidth(const Type *Ty) const { + if (TD) + return TD->getTypeSizeInBits(Ty); + else + return Ty->getPrimitiveSizeInBits(); + } + + static bool isRelatedBy(const ConstantRange &CR1, const ConstantRange &CR2, + LatticeVal LV) { + switch (LV) { + default: assert(!"Impossible lattice value!"); + case NE: + return CR1.maximalIntersectWith(CR2).isEmptySet(); + case ULT: + return CR1.getUnsignedMax().ult(CR2.getUnsignedMin()); + case ULE: + return CR1.getUnsignedMax().ule(CR2.getUnsignedMin()); + case UGT: + return CR1.getUnsignedMin().ugt(CR2.getUnsignedMax()); + case UGE: + return CR1.getUnsignedMin().uge(CR2.getUnsignedMax()); + case SLT: + return CR1.getSignedMax().slt(CR2.getSignedMin()); + case SLE: + return CR1.getSignedMax().sle(CR2.getSignedMin()); + case SGT: + return CR1.getSignedMin().sgt(CR2.getSignedMax()); + case SGE: + return CR1.getSignedMin().sge(CR2.getSignedMax()); + case LT: + return CR1.getUnsignedMax().ult(CR2.getUnsignedMin()) && + CR1.getSignedMax().slt(CR2.getUnsignedMin()); + case LE: + return CR1.getUnsignedMax().ule(CR2.getUnsignedMin()) && + CR1.getSignedMax().sle(CR2.getUnsignedMin()); + case GT: + return CR1.getUnsignedMin().ugt(CR2.getUnsignedMax()) && + CR1.getSignedMin().sgt(CR2.getSignedMax()); + case GE: + return CR1.getUnsignedMin().uge(CR2.getUnsignedMax()) && + CR1.getSignedMin().sge(CR2.getSignedMax()); + case SLTUGT: + return CR1.getSignedMax().slt(CR2.getSignedMin()) && + CR1.getUnsignedMin().ugt(CR2.getUnsignedMax()); + case SLEUGE: + return CR1.getSignedMax().sle(CR2.getSignedMin()) && + CR1.getUnsignedMin().uge(CR2.getUnsignedMax()); + case SGTULT: + return CR1.getSignedMin().sgt(CR2.getSignedMax()) && + CR1.getUnsignedMax().ult(CR2.getUnsignedMin()); + case SGEULE: + return CR1.getSignedMin().sge(CR2.getSignedMax()) && + CR1.getUnsignedMax().ule(CR2.getUnsignedMin()); + } + } + + bool isRelatedBy(unsigned n1, unsigned n2, DomTreeDFS::Node *Subtree, + LatticeVal LV) { + ConstantRange CR1 = range(n1, Subtree); + ConstantRange CR2 = range(n2, Subtree); + + // True iff all values in CR1 are LV to all values in CR2. + return isRelatedBy(CR1, CR2, LV); + } + + void addToWorklist(Value *V, Constant *C, ICmpInst::Predicate Pred, + VRPSolver *VRP); + void markBlock(VRPSolver *VRP); + + void mergeInto(Value **I, unsigned n, unsigned New, + DomTreeDFS::Node *Subtree, VRPSolver *VRP) { + ConstantRange CR_New = range(New, Subtree); + ConstantRange Merged = CR_New; + + for (; n != 0; ++I, --n) { + unsigned i = VN.valueNumber(*I, Subtree); + ConstantRange CR_Kill = i ? range(i, Subtree) : range(*I); + if (CR_Kill.isFullSet()) continue; + Merged = Merged.maximalIntersectWith(CR_Kill); + } + + if (Merged.isFullSet() || Merged == CR_New) return; + + applyRange(New, Merged, Subtree, VRP); + } + + void applyRange(unsigned n, const ConstantRange &CR, + DomTreeDFS::Node *Subtree, VRPSolver *VRP) { + ConstantRange Merged = CR.maximalIntersectWith(range(n, Subtree)); + if (Merged.isEmptySet()) { + markBlock(VRP); + return; + } + + if (const APInt *I = Merged.getSingleElement()) { + Value *V = VN.value(n); // XXX: redesign worklist. + const Type *Ty = V->getType(); + if (Ty->isInteger()) { + addToWorklist(V, ConstantInt::get(*I), ICmpInst::ICMP_EQ, VRP); + return; + } else if (const PointerType *PTy = dyn_cast<PointerType>(Ty)) { + assert(*I == 0 && "Pointer is null but not zero?"); + addToWorklist(V, ConstantPointerNull::get(PTy), + ICmpInst::ICMP_EQ, VRP); + return; + } + } + + update(n, Merged, Subtree); + } + + void addNotEquals(unsigned n1, unsigned n2, DomTreeDFS::Node *Subtree, + VRPSolver *VRP) { + ConstantRange CR1 = range(n1, Subtree); + ConstantRange CR2 = range(n2, Subtree); + + uint32_t W = CR1.getBitWidth(); + + if (const APInt *I = CR1.getSingleElement()) { + if (CR2.isFullSet()) { + ConstantRange NewCR2(CR1.getUpper(), CR1.getLower()); + applyRange(n2, NewCR2, Subtree, VRP); + } else if (*I == CR2.getLower()) { + APInt NewLower(CR2.getLower() + 1), + NewUpper(CR2.getUpper()); + if (NewLower == NewUpper) + NewLower = NewUpper = APInt::getMinValue(W); + + ConstantRange NewCR2(NewLower, NewUpper); + applyRange(n2, NewCR2, Subtree, VRP); + } else if (*I == CR2.getUpper() - 1) { + APInt NewLower(CR2.getLower()), + NewUpper(CR2.getUpper() - 1); + if (NewLower == NewUpper) + NewLower = NewUpper = APInt::getMinValue(W); + + ConstantRange NewCR2(NewLower, NewUpper); + applyRange(n2, NewCR2, Subtree, VRP); + } + } + + if (const APInt *I = CR2.getSingleElement()) { + if (CR1.isFullSet()) { + ConstantRange NewCR1(CR2.getUpper(), CR2.getLower()); + applyRange(n1, NewCR1, Subtree, VRP); + } else if (*I == CR1.getLower()) { + APInt NewLower(CR1.getLower() + 1), + NewUpper(CR1.getUpper()); + if (NewLower == NewUpper) + NewLower = NewUpper = APInt::getMinValue(W); + + ConstantRange NewCR1(NewLower, NewUpper); + applyRange(n1, NewCR1, Subtree, VRP); + } else if (*I == CR1.getUpper() - 1) { + APInt NewLower(CR1.getLower()), + NewUpper(CR1.getUpper() - 1); + if (NewLower == NewUpper) + NewLower = NewUpper = APInt::getMinValue(W); + + ConstantRange NewCR1(NewLower, NewUpper); + applyRange(n1, NewCR1, Subtree, VRP); + } + } + } + + void addInequality(unsigned n1, unsigned n2, DomTreeDFS::Node *Subtree, + LatticeVal LV, VRPSolver *VRP) { + assert(!isRelatedBy(n1, n2, Subtree, LV) && "Asked to do useless work."); + + if (LV == NE) { + addNotEquals(n1, n2, Subtree, VRP); + return; + } + + ConstantRange CR1 = range(n1, Subtree); + ConstantRange CR2 = range(n2, Subtree); + + if (!CR1.isSingleElement()) { + ConstantRange NewCR1 = CR1.maximalIntersectWith(create(LV, CR2)); + if (NewCR1 != CR1) + applyRange(n1, NewCR1, Subtree, VRP); + } + + if (!CR2.isSingleElement()) { + ConstantRange NewCR2 = CR2.maximalIntersectWith( + create(reversePredicate(LV), CR1)); + if (NewCR2 != CR2) + applyRange(n2, NewCR2, Subtree, VRP); + } + } + }; + + /// UnreachableBlocks keeps tracks of blocks that are for one reason or + /// another discovered to be unreachable. This is used to cull the graph when + /// analyzing instructions, and to mark blocks with the "unreachable" + /// terminator instruction after the function has executed. + class VISIBILITY_HIDDEN UnreachableBlocks { + private: + std::vector<BasicBlock *> DeadBlocks; + + public: + /// mark - mark a block as dead + void mark(BasicBlock *BB) { + std::vector<BasicBlock *>::iterator E = DeadBlocks.end(); + std::vector<BasicBlock *>::iterator I = + std::lower_bound(DeadBlocks.begin(), E, BB); + + if (I == E || *I != BB) DeadBlocks.insert(I, BB); + } + + /// isDead - returns whether a block is known to be dead already + bool isDead(BasicBlock *BB) { + std::vector<BasicBlock *>::iterator E = DeadBlocks.end(); + std::vector<BasicBlock *>::iterator I = + std::lower_bound(DeadBlocks.begin(), E, BB); + + return I != E && *I == BB; + } + + /// kill - replace the dead blocks' terminator with an UnreachableInst. + bool kill() { + bool modified = false; + for (std::vector<BasicBlock *>::iterator I = DeadBlocks.begin(), + E = DeadBlocks.end(); I != E; ++I) { + BasicBlock *BB = *I; + + DOUT << "unreachable block: " << BB->getName() << "\n"; + + for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB); + SI != SE; ++SI) { + BasicBlock *Succ = *SI; + Succ->removePredecessor(BB); + } + + TerminatorInst *TI = BB->getTerminator(); + TI->replaceAllUsesWith(UndefValue::get(TI->getType())); + TI->eraseFromParent(); + new UnreachableInst(BB); + ++NumBlocks; + modified = true; + } + DeadBlocks.clear(); + return modified; + } + }; + + /// VRPSolver keeps track of how changes to one variable affect other + /// variables, and forwards changes along to the InequalityGraph. It + /// also maintains the correct choice for "canonical" in the IG. + /// @brief VRPSolver calculates inferences from a new relationship. + class VISIBILITY_HIDDEN VRPSolver { + private: + friend class ValueRanges; + + struct Operation { + Value *LHS, *RHS; + ICmpInst::Predicate Op; + + BasicBlock *ContextBB; // XXX use a DomTreeDFS::Node instead + Instruction *ContextInst; + }; + std::deque<Operation> WorkList; + + ValueNumbering &VN; + InequalityGraph &IG; + UnreachableBlocks &UB; + ValueRanges &VR; + DomTreeDFS *DTDFS; + DomTreeDFS::Node *Top; + BasicBlock *TopBB; + Instruction *TopInst; + bool &modified; + + typedef InequalityGraph::Node Node; + + // below - true if the Instruction is dominated by the current context + // block or instruction + bool below(Instruction *I) { + BasicBlock *BB = I->getParent(); + if (TopInst && TopInst->getParent() == BB) { + if (isa<TerminatorInst>(TopInst)) return false; + if (isa<TerminatorInst>(I)) return true; + if ( isa<PHINode>(TopInst) && !isa<PHINode>(I)) return true; + if (!isa<PHINode>(TopInst) && isa<PHINode>(I)) return false; + + for (BasicBlock::const_iterator Iter = BB->begin(), E = BB->end(); + Iter != E; ++Iter) { + if (&*Iter == TopInst) return true; + else if (&*Iter == I) return false; + } + assert(!"Instructions not found in parent BasicBlock?"); + } else { + DomTreeDFS::Node *Node = DTDFS->getNodeForBlock(BB); + if (!Node) return false; + return Top->dominates(Node); + } + return false; // Not reached + } + + // aboveOrBelow - true if the Instruction either dominates or is dominated + // by the current context block or instruction + bool aboveOrBelow(Instruction *I) { + BasicBlock *BB = I->getParent(); + DomTreeDFS::Node *Node = DTDFS->getNodeForBlock(BB); + if (!Node) return false; + + return Top == Node || Top->dominates(Node) || Node->dominates(Top); + } + + bool makeEqual(Value *V1, Value *V2) { + DOUT << "makeEqual(" << *V1 << ", " << *V2 << ")\n"; + DOUT << "context is "; + if (TopInst) DOUT << "I: " << *TopInst << "\n"; + else DOUT << "BB: " << TopBB->getName() + << "(" << Top->getDFSNumIn() << ")\n"; + + assert(V1->getType() == V2->getType() && + "Can't make two values with different types equal."); + + if (V1 == V2) return true; + + if (isa<Constant>(V1) && isa<Constant>(V2)) + return false; + + unsigned n1 = VN.valueNumber(V1, Top), n2 = VN.valueNumber(V2, Top); + + if (n1 && n2) { + if (n1 == n2) return true; + if (IG.isRelatedBy(n1, n2, Top, NE)) return false; + } + + if (n1) assert(V1 == VN.value(n1) && "Value isn't canonical."); + if (n2) assert(V2 == VN.value(n2) && "Value isn't canonical."); + + assert(!VN.compare(V2, V1) && "Please order parameters to makeEqual."); + + assert(!isa<Constant>(V2) && "Tried to remove a constant."); + + SetVector<unsigned> Remove; + if (n2) Remove.insert(n2); + + if (n1 && n2) { + // Suppose we're being told that %x == %y, and %x <= %z and %y >= %z. + // We can't just merge %x and %y because the relationship with %z would + // be EQ and that's invalid. What we're doing is looking for any nodes + // %z such that %x <= %z and %y >= %z, and vice versa. + + Node::iterator end = IG.node(n2)->end(); + + // Find the intersection between N1 and N2 which is dominated by + // Top. If we find %x where N1 <= %x <= N2 (or >=) then add %x to + // Remove. + for (Node::iterator I = IG.node(n1)->begin(), E = IG.node(n1)->end(); + I != E; ++I) { + if (!(I->LV & EQ_BIT) || !Top->DominatedBy(I->Subtree)) continue; + + unsigned ILV_s = I->LV & (SLT_BIT|SGT_BIT); + unsigned ILV_u = I->LV & (ULT_BIT|UGT_BIT); + Node::iterator NI = IG.node(n2)->find(I->To, Top); + if (NI != end) { + LatticeVal NILV = reversePredicate(NI->LV); + unsigned NILV_s = NILV & (SLT_BIT|SGT_BIT); + unsigned NILV_u = NILV & (ULT_BIT|UGT_BIT); + + if ((ILV_s != (SLT_BIT|SGT_BIT) && ILV_s == NILV_s) || + (ILV_u != (ULT_BIT|UGT_BIT) && ILV_u == NILV_u)) + Remove.insert(I->To); + } + } + + // See if one of the nodes about to be removed is actually a better + // canonical choice than n1. + unsigned orig_n1 = n1; + SetVector<unsigned>::iterator DontRemove = Remove.end(); + for (SetVector<unsigned>::iterator I = Remove.begin()+1 /* skip n2 */, + E = Remove.end(); I != E; ++I) { + unsigned n = *I; + Value *V = VN.value(n); + if (VN.compare(V, V1)) { + V1 = V; + n1 = n; + DontRemove = I; + } + } + if (DontRemove != Remove.end()) { + unsigned n = *DontRemove; + Remove.remove(n); + Remove.insert(orig_n1); + } + } + + // We'd like to allow makeEqual on two values to perform a simple + // substitution without creating nodes in the IG whenever possible. + // + // The first iteration through this loop operates on V2 before going + // through the Remove list and operating on those too. If all of the + // iterations performed simple replacements then we exit early. + bool mergeIGNode = false; + unsigned i = 0; + for (Value *R = V2; i == 0 || i < Remove.size(); ++i) { + if (i) R = VN.value(Remove[i]); // skip n2. + + // Try to replace the whole instruction. If we can, we're done. + Instruction *I2 = dyn_cast<Instruction>(R); + if (I2 && below(I2)) { + std::vector<Instruction *> ToNotify; + for (Value::use_iterator UI = R->use_begin(), UE = R->use_end(); + UI != UE;) { + Use &TheUse = UI.getUse(); + ++UI; + if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser())) + ToNotify.push_back(I); + } + + DOUT << "Simply removing " << *I2 + << ", replacing with " << *V1 << "\n"; + I2->replaceAllUsesWith(V1); + // leave it dead; it'll get erased later. + ++NumInstruction; + modified = true; + + for (std::vector<Instruction *>::iterator II = ToNotify.begin(), + IE = ToNotify.end(); II != IE; ++II) { + opsToDef(*II); + } + + continue; + } + + // Otherwise, replace all dominated uses. + for (Value::use_iterator UI = R->use_begin(), UE = R->use_end(); + UI != UE;) { + Use &TheUse = UI.getUse(); + ++UI; + if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser())) { + if (below(I)) { + TheUse.set(V1); + modified = true; + ++NumVarsReplaced; + opsToDef(I); + } + } + } + + // If that killed the instruction, stop here. + if (I2 && isInstructionTriviallyDead(I2)) { + DOUT << "Killed all uses of " << *I2 + << ", replacing with " << *V1 << "\n"; + continue; + } + + // If we make it to here, then we will need to create a node for N1. + // Otherwise, we can skip out early! + mergeIGNode = true; + } + + if (!isa<Constant>(V1)) { + if (Remove.empty()) { + VR.mergeInto(&V2, 1, VN.getOrInsertVN(V1, Top), Top, this); + } else { + std::vector<Value*> RemoveVals; + RemoveVals.reserve(Remove.size()); + + for (SetVector<unsigned>::iterator I = Remove.begin(), + E = Remove.end(); I != E; ++I) { + Value *V = VN.value(*I); + if (!V->use_empty()) + RemoveVals.push_back(V); + } + VR.mergeInto(&RemoveVals[0], RemoveVals.size(), + VN.getOrInsertVN(V1, Top), Top, this); + } + } + + if (mergeIGNode) { + // Create N1. + if (!n1) n1 = VN.getOrInsertVN(V1, Top); + IG.node(n1); // Ensure that IG.Nodes won't get resized + + // Migrate relationships from removed nodes to N1. + for (SetVector<unsigned>::iterator I = Remove.begin(), E = Remove.end(); + I != E; ++I) { + unsigned n = *I; + for (Node::iterator NI = IG.node(n)->begin(), NE = IG.node(n)->end(); + NI != NE; ++NI) { + if (NI->Subtree->DominatedBy(Top)) { + if (NI->To == n1) { + assert((NI->LV & EQ_BIT) && "Node inequal to itself."); + continue; + } + if (Remove.count(NI->To)) + continue; + + IG.node(NI->To)->update(n1, reversePredicate(NI->LV), Top); + IG.node(n1)->update(NI->To, NI->LV, Top); + } + } + } + + // Point V2 (and all items in Remove) to N1. + if (!n2) + VN.addEquality(n1, V2, Top); + else { + for (SetVector<unsigned>::iterator I = Remove.begin(), + E = Remove.end(); I != E; ++I) { + VN.addEquality(n1, VN.value(*I), Top); + } + } + + // If !Remove.empty() then V2 = Remove[0]->getValue(). + // Even when Remove is empty, we still want to process V2. + i = 0; + for (Value *R = V2; i == 0 || i < Remove.size(); ++i) { + if (i) R = VN.value(Remove[i]); // skip n2. + + if (Instruction *I2 = dyn_cast<Instruction>(R)) { + if (aboveOrBelow(I2)) + defToOps(I2); + } + for (Value::use_iterator UI = V2->use_begin(), UE = V2->use_end(); + UI != UE;) { + Use &TheUse = UI.getUse(); + ++UI; + if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser())) { + if (aboveOrBelow(I)) + opsToDef(I); + } + } + } + } + + // re-opsToDef all dominated users of V1. + if (Instruction *I = dyn_cast<Instruction>(V1)) { + for (Value::use_iterator UI = I->use_begin(), UE = I->use_end(); + UI != UE;) { + Use &TheUse = UI.getUse(); + ++UI; + Value *V = TheUse.getUser(); + if (!V->use_empty()) { + if (Instruction *Inst = dyn_cast<Instruction>(V)) { + if (aboveOrBelow(Inst)) + opsToDef(Inst); + } + } + } + } + + return true; + } + + /// cmpInstToLattice - converts an CmpInst::Predicate to lattice value + /// Requires that the lattice value be valid; does not accept ICMP_EQ. + static LatticeVal cmpInstToLattice(ICmpInst::Predicate Pred) { + switch (Pred) { + case ICmpInst::ICMP_EQ: + assert(!"No matching lattice value."); + return static_cast<LatticeVal>(EQ_BIT); + default: + assert(!"Invalid 'icmp' predicate."); + case ICmpInst::ICMP_NE: + return NE; + case ICmpInst::ICMP_UGT: + return UGT; + case ICmpInst::ICMP_UGE: + return UGE; + case ICmpInst::ICMP_ULT: + return ULT; + case ICmpInst::ICMP_ULE: + return ULE; + case ICmpInst::ICMP_SGT: + return SGT; + case ICmpInst::ICMP_SGE: + return SGE; + case ICmpInst::ICMP_SLT: + return SLT; + case ICmpInst::ICMP_SLE: + return SLE; + } + } + + public: + VRPSolver(ValueNumbering &VN, InequalityGraph &IG, UnreachableBlocks &UB, + ValueRanges &VR, DomTreeDFS *DTDFS, bool &modified, + BasicBlock *TopBB) + : VN(VN), + IG(IG), + UB(UB), + VR(VR), + DTDFS(DTDFS), + Top(DTDFS->getNodeForBlock(TopBB)), + TopBB(TopBB), + TopInst(NULL), + modified(modified) + { + assert(Top && "VRPSolver created for unreachable basic block."); + } + + VRPSolver(ValueNumbering &VN, InequalityGraph &IG, UnreachableBlocks &UB, + ValueRanges &VR, DomTreeDFS *DTDFS, bool &modified, + Instruction *TopInst) + : VN(VN), + IG(IG), + UB(UB), + VR(VR), + DTDFS(DTDFS), + Top(DTDFS->getNodeForBlock(TopInst->getParent())), + TopBB(TopInst->getParent()), + TopInst(TopInst), + modified(modified) + { + assert(Top && "VRPSolver created for unreachable basic block."); + assert(Top->getBlock() == TopInst->getParent() && "Context mismatch."); + } + + bool isRelatedBy(Value *V1, Value *V2, ICmpInst::Predicate Pred) const { + if (Constant *C1 = dyn_cast<Constant>(V1)) + if (Constant *C2 = dyn_cast<Constant>(V2)) + return ConstantExpr::getCompare(Pred, C1, C2) == + ConstantInt::getTrue(); + + unsigned n1 = VN.valueNumber(V1, Top); + unsigned n2 = VN.valueNumber(V2, Top); + + if (n1 && n2) { + if (n1 == n2) return Pred == ICmpInst::ICMP_EQ || + Pred == ICmpInst::ICMP_ULE || + Pred == ICmpInst::ICMP_UGE || + Pred == ICmpInst::ICMP_SLE || + Pred == ICmpInst::ICMP_SGE; + if (Pred == ICmpInst::ICMP_EQ) return false; + if (IG.isRelatedBy(n1, n2, Top, cmpInstToLattice(Pred))) return true; + if (VR.isRelatedBy(n1, n2, Top, cmpInstToLattice(Pred))) return true; + } + + if ((n1 && !n2 && isa<Constant>(V2)) || + (n2 && !n1 && isa<Constant>(V1))) { + ConstantRange CR1 = n1 ? VR.range(n1, Top) : VR.range(V1); + ConstantRange CR2 = n2 ? VR.range(n2, Top) : VR.range(V2); + + if (Pred == ICmpInst::ICMP_EQ) + return CR1.isSingleElement() && + CR1.getSingleElement() == CR2.getSingleElement(); + + return VR.isRelatedBy(CR1, CR2, cmpInstToLattice(Pred)); + } + if (Pred == ICmpInst::ICMP_EQ) return V1 == V2; + return false; + } + + /// add - adds a new property to the work queue + void add(Value *V1, Value *V2, ICmpInst::Predicate Pred, + Instruction *I = NULL) { + DOUT << "adding " << *V1 << " " << Pred << " " << *V2; + if (I) DOUT << " context: " << *I; + else DOUT << " default context (" << Top->getDFSNumIn() << ")"; + DOUT << "\n"; + + assert(V1->getType() == V2->getType() && + "Can't relate two values with different types."); + + WorkList.push_back(Operation()); + Operation &O = WorkList.back(); + O.LHS = V1, O.RHS = V2, O.Op = Pred, O.ContextInst = I; + O.ContextBB = I ? I->getParent() : TopBB; + } + + /// defToOps - Given an instruction definition that we've learned something + /// new about, find any new relationships between its operands. + void defToOps(Instruction *I) { + Instruction *NewContext = below(I) ? I : TopInst; + Value *Canonical = VN.canonicalize(I, Top); + + if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) { + const Type *Ty = BO->getType(); + assert(!Ty->isFPOrFPVector() && "Float in work queue!"); + + Value *Op0 = VN.canonicalize(BO->getOperand(0), Top); + Value *Op1 = VN.canonicalize(BO->getOperand(1), Top); + + // TODO: "and i32 -1, %x" EQ %y then %x EQ %y. + + switch (BO->getOpcode()) { + case Instruction::And: { + // "and i32 %a, %b" EQ -1 then %a EQ -1 and %b EQ -1 + ConstantInt *CI = ConstantInt::getAllOnesValue(Ty); + if (Canonical == CI) { + add(CI, Op0, ICmpInst::ICMP_EQ, NewContext); + add(CI, Op1, ICmpInst::ICMP_EQ, NewContext); + } + } break; + case Instruction::Or: { + // "or i32 %a, %b" EQ 0 then %a EQ 0 and %b EQ 0 + Constant *Zero = Constant::getNullValue(Ty); + if (Canonical == Zero) { + add(Zero, Op0, ICmpInst::ICMP_EQ, NewContext); + add(Zero, Op1, ICmpInst::ICMP_EQ, NewContext); + } + } break; + case Instruction::Xor: { + // "xor i32 %c, %a" EQ %b then %a EQ %c ^ %b + // "xor i32 %c, %a" EQ %c then %a EQ 0 + // "xor i32 %c, %a" NE %c then %a NE 0 + // Repeat the above, with order of operands reversed. + Value *LHS = Op0; + Value *RHS = Op1; + if (!isa<Constant>(LHS)) std::swap(LHS, RHS); + + if (ConstantInt *CI = dyn_cast<ConstantInt>(Canonical)) { + if (ConstantInt *Arg = dyn_cast<ConstantInt>(LHS)) { + add(RHS, ConstantInt::get(CI->getValue() ^ Arg->getValue()), + ICmpInst::ICMP_EQ, NewContext); + } + } + if (Canonical == LHS) { + if (isa<ConstantInt>(Canonical)) + add(RHS, Constant::getNullValue(Ty), ICmpInst::ICMP_EQ, + NewContext); + } else if (isRelatedBy(LHS, Canonical, ICmpInst::ICMP_NE)) { + add(RHS, Constant::getNullValue(Ty), ICmpInst::ICMP_NE, + NewContext); + } + } break; + default: + break; + } + } else if (ICmpInst *IC = dyn_cast<ICmpInst>(I)) { + // "icmp ult i32 %a, %y" EQ true then %a u< y + // etc. + + if (Canonical == ConstantInt::getTrue()) { + add(IC->getOperand(0), IC->getOperand(1), IC->getPredicate(), + NewContext); + } else if (Canonical == ConstantInt::getFalse()) { + add(IC->getOperand(0), IC->getOperand(1), + ICmpInst::getInversePredicate(IC->getPredicate()), NewContext); + } + } else if (SelectInst *SI = dyn_cast<SelectInst>(I)) { + if (I->getType()->isFPOrFPVector()) return; + + // Given: "%a = select i1 %x, i32 %b, i32 %c" + // %a EQ %b and %b NE %c then %x EQ true + // %a EQ %c and %b NE %c then %x EQ false + + Value *True = SI->getTrueValue(); + Value *False = SI->getFalseValue(); + if (isRelatedBy(True, False, ICmpInst::ICMP_NE)) { + if (Canonical == VN.canonicalize(True, Top) || + isRelatedBy(Canonical, False, ICmpInst::ICMP_NE)) + add(SI->getCondition(), ConstantInt::getTrue(), + ICmpInst::ICMP_EQ, NewContext); + else if (Canonical == VN.canonicalize(False, Top) || + isRelatedBy(Canonical, True, ICmpInst::ICMP_NE)) + add(SI->getCondition(), ConstantInt::getFalse(), + ICmpInst::ICMP_EQ, NewContext); + } + } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) { + for (GetElementPtrInst::op_iterator OI = GEPI->idx_begin(), + OE = GEPI->idx_end(); OI != OE; ++OI) { + ConstantInt *Op = dyn_cast<ConstantInt>(VN.canonicalize(*OI, Top)); + if (!Op || !Op->isZero()) return; + } + // TODO: The GEPI indices are all zero. Copy from definition to operand, + // jumping the type plane as needed. + if (isRelatedBy(GEPI, Constant::getNullValue(GEPI->getType()), + ICmpInst::ICMP_NE)) { + Value *Ptr = GEPI->getPointerOperand(); + add(Ptr, Constant::getNullValue(Ptr->getType()), ICmpInst::ICMP_NE, + NewContext); + } + } else if (CastInst *CI = dyn_cast<CastInst>(I)) { + const Type *SrcTy = CI->getSrcTy(); + + unsigned ci = VN.getOrInsertVN(CI, Top); + uint32_t W = VR.typeToWidth(SrcTy); + if (!W) return; + ConstantRange CR = VR.range(ci, Top); + + if (CR.isFullSet()) return; + + switch (CI->getOpcode()) { + default: break; + case Instruction::ZExt: + case Instruction::SExt: + VR.applyRange(VN.getOrInsertVN(CI->getOperand(0), Top), + CR.truncate(W), Top, this); + break; + case Instruction::BitCast: + VR.applyRange(VN.getOrInsertVN(CI->getOperand(0), Top), + CR, Top, this); + break; + } + } + } + + /// opsToDef - A new relationship was discovered involving one of this + /// instruction's operands. Find any new relationship involving the + /// definition, or another operand. + void opsToDef(Instruction *I) { + Instruction *NewContext = below(I) ? I : TopInst; + + if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) { + Value *Op0 = VN.canonicalize(BO->getOperand(0), Top); + Value *Op1 = VN.canonicalize(BO->getOperand(1), Top); + + if (ConstantInt *CI0 = dyn_cast<ConstantInt>(Op0)) + if (ConstantInt *CI1 = dyn_cast<ConstantInt>(Op1)) { + add(BO, ConstantExpr::get(BO->getOpcode(), CI0, CI1), + ICmpInst::ICMP_EQ, NewContext); + return; + } + + // "%y = and i1 true, %x" then %x EQ %y + // "%y = or i1 false, %x" then %x EQ %y + // "%x = add i32 %y, 0" then %x EQ %y + // "%x = mul i32 %y, 0" then %x EQ 0 + + Instruction::BinaryOps Opcode = BO->getOpcode(); + const Type *Ty = BO->getType(); + assert(!Ty->isFPOrFPVector() && "Float in work queue!"); + + Constant *Zero = Constant::getNullValue(Ty); + Constant *One = ConstantInt::get(Ty, 1); + ConstantInt *AllOnes = ConstantInt::getAllOnesValue(Ty); + + switch (Opcode) { + default: break; + case Instruction::LShr: + case Instruction::AShr: + case Instruction::Shl: + if (Op1 == Zero) { + add(BO, Op0, ICmpInst::ICMP_EQ, NewContext); + return; + } + break; + case Instruction::Sub: + if (Op1 == Zero) { + add(BO, Op0, ICmpInst::ICMP_EQ, NewContext); + return; + } + if (ConstantInt *CI0 = dyn_cast<ConstantInt>(Op0)) { + unsigned n_ci0 = VN.getOrInsertVN(Op1, Top); + ConstantRange CR = VR.range(n_ci0, Top); + if (!CR.isFullSet()) { + CR.subtract(CI0->getValue()); + unsigned n_bo = VN.getOrInsertVN(BO, Top); + VR.applyRange(n_bo, CR, Top, this); + return; + } + } + if (ConstantInt *CI1 = dyn_cast<ConstantInt>(Op1)) { + unsigned n_ci1 = VN.getOrInsertVN(Op0, Top); + ConstantRange CR = VR.range(n_ci1, Top); + if (!CR.isFullSet()) { + CR.subtract(CI1->getValue()); + unsigned n_bo = VN.getOrInsertVN(BO, Top); + VR.applyRange(n_bo, CR, Top, this); + return; + } + } + break; + case Instruction::Or: + if (Op0 == AllOnes || Op1 == AllOnes) { + add(BO, AllOnes, ICmpInst::ICMP_EQ, NewContext); + return; + } + if (Op0 == Zero) { + add(BO, Op1, ICmpInst::ICMP_EQ, NewContext); + return; + } else if (Op1 == Zero) { + add(BO, Op0, ICmpInst::ICMP_EQ, NewContext); + return; + } + break; + case Instruction::Add: + if (ConstantInt *CI0 = dyn_cast<ConstantInt>(Op0)) { + unsigned n_ci0 = VN.getOrInsertVN(Op1, Top); + ConstantRange CR = VR.range(n_ci0, Top); + if (!CR.isFullSet()) { + CR.subtract(-CI0->getValue()); + unsigned n_bo = VN.getOrInsertVN(BO, Top); + VR.applyRange(n_bo, CR, Top, this); + return; + } + } + if (ConstantInt *CI1 = dyn_cast<ConstantInt>(Op1)) { + unsigned n_ci1 = VN.getOrInsertVN(Op0, Top); + ConstantRange CR = VR.range(n_ci1, Top); + if (!CR.isFullSet()) { + CR.subtract(-CI1->getValue()); + unsigned n_bo = VN.getOrInsertVN(BO, Top); + VR.applyRange(n_bo, CR, Top, this); + return; + } + } + // fall-through + case Instruction::Xor: + if (Op0 == Zero) { + add(BO, Op1, ICmpInst::ICMP_EQ, NewContext); + return; + } else if (Op1 == Zero) { + add(BO, Op0, ICmpInst::ICMP_EQ, NewContext); + return; + } + break; + case Instruction::And: + if (Op0 == AllOnes) { + add(BO, Op1, ICmpInst::ICMP_EQ, NewContext); + return; + } else if (Op1 == AllOnes) { + add(BO, Op0, ICmpInst::ICMP_EQ, NewContext); + return; + } + if (Op0 == Zero || Op1 == Zero) { + add(BO, Zero, ICmpInst::ICMP_EQ, NewContext); + return; + } + break; + case Instruction::Mul: + if (Op0 == Zero || Op1 == Zero) { + add(BO, Zero, ICmpInst::ICMP_EQ, NewContext); + return; + } + if (Op0 == One) { + add(BO, Op1, ICmpInst::ICMP_EQ, NewContext); + return; + } else if (Op1 == One) { + add(BO, Op0, ICmpInst::ICMP_EQ, NewContext); + return; + } + break; + } + + // "%x = add i32 %y, %z" and %x EQ %y then %z EQ 0 + // "%x = add i32 %y, %z" and %x EQ %z then %y EQ 0 + // "%x = shl i32 %y, %z" and %x EQ %y and %y NE 0 then %z EQ 0 + // "%x = udiv i32 %y, %z" and %x EQ %y and %y NE 0 then %z EQ 1 + + Value *Known = Op0, *Unknown = Op1, + *TheBO = VN.canonicalize(BO, Top); + if (Known != TheBO) std::swap(Known, Unknown); + if (Known == TheBO) { + switch (Opcode) { + default: break; + case Instruction::LShr: + case Instruction::AShr: + case Instruction::Shl: + if (!isRelatedBy(Known, Zero, ICmpInst::ICMP_NE)) break; + // otherwise, fall-through. + case Instruction::Sub: + if (Unknown == Op0) break; + // otherwise, fall-through. + case Instruction::Xor: + case Instruction::Add: + add(Unknown, Zero, ICmpInst::ICMP_EQ, NewContext); + break; + case Instruction::UDiv: + case Instruction::SDiv: + if (Unknown == Op1) break; + if (isRelatedBy(Known, Zero, ICmpInst::ICMP_NE)) + add(Unknown, One, ICmpInst::ICMP_EQ, NewContext); + break; + } + } + + // TODO: "%a = add i32 %b, 1" and %b > %z then %a >= %z. + + } else if (ICmpInst *IC = dyn_cast<ICmpInst>(I)) { + // "%a = icmp ult i32 %b, %c" and %b u< %c then %a EQ true + // "%a = icmp ult i32 %b, %c" and %b u>= %c then %a EQ false + // etc. + + Value *Op0 = VN.canonicalize(IC->getOperand(0), Top); + Value *Op1 = VN.canonicalize(IC->getOperand(1), Top); + + ICmpInst::Predicate Pred = IC->getPredicate(); + if (isRelatedBy(Op0, Op1, Pred)) + add(IC, ConstantInt::getTrue(), ICmpInst::ICMP_EQ, NewContext); + else if (isRelatedBy(Op0, Op1, ICmpInst::getInversePredicate(Pred))) + add(IC, ConstantInt::getFalse(), ICmpInst::ICMP_EQ, NewContext); + + } else if (SelectInst *SI = dyn_cast<SelectInst>(I)) { + if (I->getType()->isFPOrFPVector()) return; + + // Given: "%a = select i1 %x, i32 %b, i32 %c" + // %x EQ true then %a EQ %b + // %x EQ false then %a EQ %c + // %b EQ %c then %a EQ %b + + Value *Canonical = VN.canonicalize(SI->getCondition(), Top); + if (Canonical == ConstantInt::getTrue()) { + add(SI, SI->getTrueValue(), ICmpInst::ICMP_EQ, NewContext); + } else if (Canonical == ConstantInt::getFalse()) { + add(SI, SI->getFalseValue(), ICmpInst::ICMP_EQ, NewContext); + } else if (VN.canonicalize(SI->getTrueValue(), Top) == + VN.canonicalize(SI->getFalseValue(), Top)) { + add(SI, SI->getTrueValue(), ICmpInst::ICMP_EQ, NewContext); + } + } else if (CastInst *CI = dyn_cast<CastInst>(I)) { + const Type *DestTy = CI->getDestTy(); + if (DestTy->isFPOrFPVector()) return; + + Value *Op = VN.canonicalize(CI->getOperand(0), Top); + Instruction::CastOps Opcode = CI->getOpcode(); + + if (Constant *C = dyn_cast<Constant>(Op)) { + add(CI, ConstantExpr::getCast(Opcode, C, DestTy), + ICmpInst::ICMP_EQ, NewContext); + } + + uint32_t W = VR.typeToWidth(DestTy); + unsigned ci = VN.getOrInsertVN(CI, Top); + ConstantRange CR = VR.range(VN.getOrInsertVN(Op, Top), Top); + + if (!CR.isFullSet()) { + switch (Opcode) { + default: break; + case Instruction::ZExt: + VR.applyRange(ci, CR.zeroExtend(W), Top, this); + break; + case Instruction::SExt: + VR.applyRange(ci, CR.signExtend(W), Top, this); + break; + case Instruction::Trunc: { + ConstantRange Result = CR.truncate(W); + if (!Result.isFullSet()) + VR.applyRange(ci, Result, Top, this); + } break; + case Instruction::BitCast: + VR.applyRange(ci, CR, Top, this); + break; + // TODO: other casts? + } + } + } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) { + for (GetElementPtrInst::op_iterator OI = GEPI->idx_begin(), + OE = GEPI->idx_end(); OI != OE; ++OI) { + ConstantInt *Op = dyn_cast<ConstantInt>(VN.canonicalize(*OI, Top)); + if (!Op || !Op->isZero()) return; + } + // TODO: The GEPI indices are all zero. Copy from operand to definition, + // jumping the type plane as needed. + Value *Ptr = GEPI->getPointerOperand(); + if (isRelatedBy(Ptr, Constant::getNullValue(Ptr->getType()), + ICmpInst::ICMP_NE)) { + add(GEPI, Constant::getNullValue(GEPI->getType()), ICmpInst::ICMP_NE, + NewContext); + } + } + } + + /// solve - process the work queue + void solve() { + //DOUT << "WorkList entry, size: " << WorkList.size() << "\n"; + while (!WorkList.empty()) { + //DOUT << "WorkList size: " << WorkList.size() << "\n"; + + Operation &O = WorkList.front(); + TopInst = O.ContextInst; + TopBB = O.ContextBB; + Top = DTDFS->getNodeForBlock(TopBB); // XXX move this into Context + + O.LHS = VN.canonicalize(O.LHS, Top); + O.RHS = VN.canonicalize(O.RHS, Top); + + assert(O.LHS == VN.canonicalize(O.LHS, Top) && "Canonicalize isn't."); + assert(O.RHS == VN.canonicalize(O.RHS, Top) && "Canonicalize isn't."); + + DOUT << "solving " << *O.LHS << " " << O.Op << " " << *O.RHS; + if (O.ContextInst) DOUT << " context inst: " << *O.ContextInst; + else DOUT << " context block: " << O.ContextBB->getName(); + DOUT << "\n"; + + DEBUG(VN.dump()); + DEBUG(IG.dump()); + DEBUG(VR.dump()); + + // If they're both Constant, skip it. Check for contradiction and mark + // the BB as unreachable if so. + if (Constant *CI_L = dyn_cast<Constant>(O.LHS)) { + if (Constant *CI_R = dyn_cast<Constant>(O.RHS)) { + if (ConstantExpr::getCompare(O.Op, CI_L, CI_R) == + ConstantInt::getFalse()) + UB.mark(TopBB); + + WorkList.pop_front(); + continue; + } + } + + if (VN.compare(O.LHS, O.RHS)) { + std::swap(O.LHS, O.RHS); + O.Op = ICmpInst::getSwappedPredicate(O.Op); + } + + if (O.Op == ICmpInst::ICMP_EQ) { + if (!makeEqual(O.RHS, O.LHS)) + UB.mark(TopBB); + } else { + LatticeVal LV = cmpInstToLattice(O.Op); + + if ((LV & EQ_BIT) && + isRelatedBy(O.LHS, O.RHS, ICmpInst::getSwappedPredicate(O.Op))) { + if (!makeEqual(O.RHS, O.LHS)) + UB.mark(TopBB); + } else { + if (isRelatedBy(O.LHS, O.RHS, ICmpInst::getInversePredicate(O.Op))){ + UB.mark(TopBB); + WorkList.pop_front(); + continue; + } + + unsigned n1 = VN.getOrInsertVN(O.LHS, Top); + unsigned n2 = VN.getOrInsertVN(O.RHS, Top); + + if (n1 == n2) { + if (O.Op != ICmpInst::ICMP_UGE && O.Op != ICmpInst::ICMP_ULE && + O.Op != ICmpInst::ICMP_SGE && O.Op != ICmpInst::ICMP_SLE) + UB.mark(TopBB); + + WorkList.pop_front(); + continue; + } + + if (VR.isRelatedBy(n1, n2, Top, LV) || + IG.isRelatedBy(n1, n2, Top, LV)) { + WorkList.pop_front(); + continue; + } + + VR.addInequality(n1, n2, Top, LV, this); + if ((!isa<ConstantInt>(O.RHS) && !isa<ConstantInt>(O.LHS)) || + LV == NE) + IG.addInequality(n1, n2, Top, LV); + + if (Instruction *I1 = dyn_cast<Instruction>(O.LHS)) { + if (aboveOrBelow(I1)) + defToOps(I1); + } + if (isa<Instruction>(O.LHS) || isa<Argument>(O.LHS)) { + for (Value::use_iterator UI = O.LHS->use_begin(), + UE = O.LHS->use_end(); UI != UE;) { + Use &TheUse = UI.getUse(); + ++UI; + if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser())) { + if (aboveOrBelow(I)) + opsToDef(I); + } + } + } + if (Instruction *I2 = dyn_cast<Instruction>(O.RHS)) { + if (aboveOrBelow(I2)) + defToOps(I2); + } + if (isa<Instruction>(O.RHS) || isa<Argument>(O.RHS)) { + for (Value::use_iterator UI = O.RHS->use_begin(), + UE = O.RHS->use_end(); UI != UE;) { + Use &TheUse = UI.getUse(); + ++UI; + if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser())) { + if (aboveOrBelow(I)) + opsToDef(I); + } + } + } + } + } + WorkList.pop_front(); + } + } + }; + + void ValueRanges::addToWorklist(Value *V, Constant *C, + ICmpInst::Predicate Pred, VRPSolver *VRP) { + VRP->add(V, C, Pred, VRP->TopInst); + } + + void ValueRanges::markBlock(VRPSolver *VRP) { + VRP->UB.mark(VRP->TopBB); + } + + /// PredicateSimplifier - This class is a simplifier that replaces + /// one equivalent variable with another. It also tracks what + /// can't be equal and will solve setcc instructions when possible. + /// @brief Root of the predicate simplifier optimization. + class VISIBILITY_HIDDEN PredicateSimplifier : public FunctionPass { + DomTreeDFS *DTDFS; + bool modified; + ValueNumbering *VN; + InequalityGraph *IG; + UnreachableBlocks UB; + ValueRanges *VR; + + std::vector<DomTreeDFS::Node *> WorkList; + + public: + static char ID; // Pass identification, replacement for typeid + PredicateSimplifier() : FunctionPass(&ID) {} + + bool runOnFunction(Function &F); + + virtual void getAnalysisUsage(AnalysisUsage &AU) const { + AU.addRequiredID(BreakCriticalEdgesID); + AU.addRequired<DominatorTree>(); + AU.addRequired<TargetData>(); + AU.addPreserved<TargetData>(); + } + + private: + /// Forwards - Adds new properties to VRPSolver and uses them to + /// simplify instructions. Because new properties sometimes apply to + /// a transition from one BasicBlock to another, this will use the + /// PredicateSimplifier::proceedToSuccessor(s) interface to enter the + /// basic block. + /// @brief Performs abstract execution of the program. + class VISIBILITY_HIDDEN Forwards : public InstVisitor<Forwards> { + friend class InstVisitor<Forwards>; + PredicateSimplifier *PS; + DomTreeDFS::Node *DTNode; + + public: + ValueNumbering &VN; + InequalityGraph &IG; + UnreachableBlocks &UB; + ValueRanges &VR; + + Forwards(PredicateSimplifier *PS, DomTreeDFS::Node *DTNode) + : PS(PS), DTNode(DTNode), VN(*PS->VN), IG(*PS->IG), UB(PS->UB), + VR(*PS->VR) {} + + void visitTerminatorInst(TerminatorInst &TI); + void visitBranchInst(BranchInst &BI); + void visitSwitchInst(SwitchInst &SI); + + void visitAllocaInst(AllocaInst &AI); + void visitLoadInst(LoadInst &LI); + void visitStoreInst(StoreInst &SI); + + void visitSExtInst(SExtInst &SI); + void visitZExtInst(ZExtInst &ZI); + + void visitBinaryOperator(BinaryOperator &BO); + void visitICmpInst(ICmpInst &IC); + }; + + // Used by terminator instructions to proceed from the current basic + // block to the next. Verifies that "current" dominates "next", + // then calls visitBasicBlock. + void proceedToSuccessors(DomTreeDFS::Node *Current) { + for (DomTreeDFS::Node::iterator I = Current->begin(), + E = Current->end(); I != E; ++I) { + WorkList.push_back(*I); + } + } + + void proceedToSuccessor(DomTreeDFS::Node *Next) { + WorkList.push_back(Next); + } + + // Visits each instruction in the basic block. + void visitBasicBlock(DomTreeDFS::Node *Node) { + BasicBlock *BB = Node->getBlock(); + DOUT << "Entering Basic Block: " << BB->getName() + << " (" << Node->getDFSNumIn() << ")\n"; + for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) { + visitInstruction(I++, Node); + } + } + + // Tries to simplify each Instruction and add new properties. + void visitInstruction(Instruction *I, DomTreeDFS::Node *DT) { + DOUT << "Considering instruction " << *I << "\n"; + DEBUG(VN->dump()); + DEBUG(IG->dump()); + DEBUG(VR->dump()); + + // Sometimes instructions are killed in earlier analysis. + if (isInstructionTriviallyDead(I)) { + ++NumSimple; + modified = true; + if (unsigned n = VN->valueNumber(I, DTDFS->getRootNode())) + if (VN->value(n) == I) IG->remove(n); + VN->remove(I); + I->eraseFromParent(); + return; + } + +#ifndef NDEBUG + // Try to replace the whole instruction. + Value *V = VN->canonicalize(I, DT); + assert(V == I && "Late instruction canonicalization."); + if (V != I) { + modified = true; + ++NumInstruction; + DOUT << "Removing " << *I << ", replacing with " << *V << "\n"; + if (unsigned n = VN->valueNumber(I, DTDFS->getRootNode())) + if (VN->value(n) == I) IG->remove(n); + VN->remove(I); + I->replaceAllUsesWith(V); + I->eraseFromParent(); + return; + } + + // Try to substitute operands. + for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) { + Value *Oper = I->getOperand(i); + Value *V = VN->canonicalize(Oper, DT); + assert(V == Oper && "Late operand canonicalization."); + if (V != Oper) { + modified = true; + ++NumVarsReplaced; + DOUT << "Resolving " << *I; + I->setOperand(i, V); + DOUT << " into " << *I; + } + } +#endif + + std::string name = I->getParent()->getName(); + DOUT << "push (%" << name << ")\n"; + Forwards visit(this, DT); + visit.visit(*I); + DOUT << "pop (%" << name << ")\n"; + } + }; + + bool PredicateSimplifier::runOnFunction(Function &F) { + DominatorTree *DT = &getAnalysis<DominatorTree>(); + DTDFS = new DomTreeDFS(DT); + TargetData *TD = &getAnalysis<TargetData>(); + + DOUT << "Entering Function: " << F.getName() << "\n"; + + modified = false; + DomTreeDFS::Node *Root = DTDFS->getRootNode(); + VN = new ValueNumbering(DTDFS); + IG = new InequalityGraph(*VN, Root); + VR = new ValueRanges(*VN, TD); + WorkList.push_back(Root); + + do { + DomTreeDFS::Node *DTNode = WorkList.back(); + WorkList.pop_back(); + if (!UB.isDead(DTNode->getBlock())) visitBasicBlock(DTNode); + } while (!WorkList.empty()); + + delete DTDFS; + delete VR; + delete IG; + delete VN; + + modified |= UB.kill(); + + return modified; + } + + void PredicateSimplifier::Forwards::visitTerminatorInst(TerminatorInst &TI) { + PS->proceedToSuccessors(DTNode); + } + + void PredicateSimplifier::Forwards::visitBranchInst(BranchInst &BI) { + if (BI.isUnconditional()) { + PS->proceedToSuccessors(DTNode); + return; + } + + Value *Condition = BI.getCondition(); + BasicBlock *TrueDest = BI.getSuccessor(0); + BasicBlock *FalseDest = BI.getSuccessor(1); + + if (isa<Constant>(Condition) || TrueDest == FalseDest) { + PS->proceedToSuccessors(DTNode); + return; + } + + for (DomTreeDFS::Node::iterator I = DTNode->begin(), E = DTNode->end(); + I != E; ++I) { + BasicBlock *Dest = (*I)->getBlock(); + DOUT << "Branch thinking about %" << Dest->getName() + << "(" << PS->DTDFS->getNodeForBlock(Dest)->getDFSNumIn() << ")\n"; + + if (Dest == TrueDest) { + DOUT << "(" << DTNode->getBlock()->getName() << ") true set:\n"; + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, Dest); + VRP.add(ConstantInt::getTrue(), Condition, ICmpInst::ICMP_EQ); + VRP.solve(); + DEBUG(VN.dump()); + DEBUG(IG.dump()); + DEBUG(VR.dump()); + } else if (Dest == FalseDest) { + DOUT << "(" << DTNode->getBlock()->getName() << ") false set:\n"; + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, Dest); + VRP.add(ConstantInt::getFalse(), Condition, ICmpInst::ICMP_EQ); + VRP.solve(); + DEBUG(VN.dump()); + DEBUG(IG.dump()); + DEBUG(VR.dump()); + } + + PS->proceedToSuccessor(*I); + } + } + + void PredicateSimplifier::Forwards::visitSwitchInst(SwitchInst &SI) { + Value *Condition = SI.getCondition(); + + // Set the EQProperty in each of the cases BBs, and the NEProperties + // in the default BB. + + for (DomTreeDFS::Node::iterator I = DTNode->begin(), E = DTNode->end(); + I != E; ++I) { + BasicBlock *BB = (*I)->getBlock(); + DOUT << "Switch thinking about BB %" << BB->getName() + << "(" << PS->DTDFS->getNodeForBlock(BB)->getDFSNumIn() << ")\n"; + + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, BB); + if (BB == SI.getDefaultDest()) { + for (unsigned i = 1, e = SI.getNumCases(); i < e; ++i) + if (SI.getSuccessor(i) != BB) + VRP.add(Condition, SI.getCaseValue(i), ICmpInst::ICMP_NE); + VRP.solve(); + } else if (ConstantInt *CI = SI.findCaseDest(BB)) { + VRP.add(Condition, CI, ICmpInst::ICMP_EQ); + VRP.solve(); + } + PS->proceedToSuccessor(*I); + } + } + + void PredicateSimplifier::Forwards::visitAllocaInst(AllocaInst &AI) { + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &AI); + VRP.add(Constant::getNullValue(AI.getType()), &AI, ICmpInst::ICMP_NE); + VRP.solve(); + } + + void PredicateSimplifier::Forwards::visitLoadInst(LoadInst &LI) { + Value *Ptr = LI.getPointerOperand(); + // avoid "load i8* null" -> null NE null. + if (isa<Constant>(Ptr)) return; + + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &LI); + VRP.add(Constant::getNullValue(Ptr->getType()), Ptr, ICmpInst::ICMP_NE); + VRP.solve(); + } + + void PredicateSimplifier::Forwards::visitStoreInst(StoreInst &SI) { + Value *Ptr = SI.getPointerOperand(); + if (isa<Constant>(Ptr)) return; + + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &SI); + VRP.add(Constant::getNullValue(Ptr->getType()), Ptr, ICmpInst::ICMP_NE); + VRP.solve(); + } + + void PredicateSimplifier::Forwards::visitSExtInst(SExtInst &SI) { + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &SI); + uint32_t SrcBitWidth = cast<IntegerType>(SI.getSrcTy())->getBitWidth(); + uint32_t DstBitWidth = cast<IntegerType>(SI.getDestTy())->getBitWidth(); + APInt Min(APInt::getHighBitsSet(DstBitWidth, DstBitWidth-SrcBitWidth+1)); + APInt Max(APInt::getLowBitsSet(DstBitWidth, SrcBitWidth-1)); + VRP.add(ConstantInt::get(Min), &SI, ICmpInst::ICMP_SLE); + VRP.add(ConstantInt::get(Max), &SI, ICmpInst::ICMP_SGE); + VRP.solve(); + } + + void PredicateSimplifier::Forwards::visitZExtInst(ZExtInst &ZI) { + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &ZI); + uint32_t SrcBitWidth = cast<IntegerType>(ZI.getSrcTy())->getBitWidth(); + uint32_t DstBitWidth = cast<IntegerType>(ZI.getDestTy())->getBitWidth(); + APInt Max(APInt::getLowBitsSet(DstBitWidth, SrcBitWidth)); + VRP.add(ConstantInt::get(Max), &ZI, ICmpInst::ICMP_UGE); + VRP.solve(); + } + + void PredicateSimplifier::Forwards::visitBinaryOperator(BinaryOperator &BO) { + Instruction::BinaryOps ops = BO.getOpcode(); + + switch (ops) { + default: break; + case Instruction::URem: + case Instruction::SRem: + case Instruction::UDiv: + case Instruction::SDiv: { + Value *Divisor = BO.getOperand(1); + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &BO); + VRP.add(Constant::getNullValue(Divisor->getType()), Divisor, + ICmpInst::ICMP_NE); + VRP.solve(); + break; + } + } + + switch (ops) { + default: break; + case Instruction::Shl: { + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &BO); + VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_UGE); + VRP.solve(); + } break; + case Instruction::AShr: { + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &BO); + VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_SLE); + VRP.solve(); + } break; + case Instruction::LShr: + case Instruction::UDiv: { + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &BO); + VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_ULE); + VRP.solve(); + } break; + case Instruction::URem: { + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &BO); + VRP.add(&BO, BO.getOperand(1), ICmpInst::ICMP_ULE); + VRP.solve(); + } break; + case Instruction::And: { + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &BO); + VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_ULE); + VRP.add(&BO, BO.getOperand(1), ICmpInst::ICMP_ULE); + VRP.solve(); + } break; + case Instruction::Or: { + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &BO); + VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_UGE); + VRP.add(&BO, BO.getOperand(1), ICmpInst::ICMP_UGE); + VRP.solve(); + } break; + } + } + + void PredicateSimplifier::Forwards::visitICmpInst(ICmpInst &IC) { + // If possible, squeeze the ICmp predicate into something simpler. + // Eg., if x = [0, 4) and we're being asked icmp uge %x, 3 then change + // the predicate to eq. + + // XXX: once we do full PHI handling, modifying the instruction in the + // Forwards visitor will cause missed optimizations. + + ICmpInst::Predicate Pred = IC.getPredicate(); + + switch (Pred) { + default: break; + case ICmpInst::ICMP_ULE: Pred = ICmpInst::ICMP_ULT; break; + case ICmpInst::ICMP_UGE: Pred = ICmpInst::ICMP_UGT; break; + case ICmpInst::ICMP_SLE: Pred = ICmpInst::ICMP_SLT; break; + case ICmpInst::ICMP_SGE: Pred = ICmpInst::ICMP_SGT; break; + } + if (Pred != IC.getPredicate()) { + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &IC); + if (VRP.isRelatedBy(IC.getOperand(1), IC.getOperand(0), + ICmpInst::ICMP_NE)) { + ++NumSnuggle; + PS->modified = true; + IC.setPredicate(Pred); + } + } + + Pred = IC.getPredicate(); + + if (ConstantInt *Op1 = dyn_cast<ConstantInt>(IC.getOperand(1))) { + ConstantInt *NextVal = 0; + switch (Pred) { + default: break; + case ICmpInst::ICMP_SLT: + case ICmpInst::ICMP_ULT: + if (Op1->getValue() != 0) + NextVal = ConstantInt::get(Op1->getValue()-1); + break; + case ICmpInst::ICMP_SGT: + case ICmpInst::ICMP_UGT: + if (!Op1->getValue().isAllOnesValue()) + NextVal = ConstantInt::get(Op1->getValue()+1); + break; + } + + if (NextVal) { + VRPSolver VRP(VN, IG, UB, VR, PS->DTDFS, PS->modified, &IC); + if (VRP.isRelatedBy(IC.getOperand(0), NextVal, + ICmpInst::getInversePredicate(Pred))) { + ICmpInst *NewIC = new ICmpInst(ICmpInst::ICMP_EQ, IC.getOperand(0), + NextVal, "", &IC); + NewIC->takeName(&IC); + IC.replaceAllUsesWith(NewIC); + + // XXX: prove this isn't necessary + if (unsigned n = VN.valueNumber(&IC, PS->DTDFS->getRootNode())) + if (VN.value(n) == &IC) IG.remove(n); + VN.remove(&IC); + + IC.eraseFromParent(); + ++NumSnuggle; + PS->modified = true; + } + } + } + } +} + +char PredicateSimplifier::ID = 0; +static RegisterPass<PredicateSimplifier> +X("predsimplify", "Predicate Simplifier"); + +FunctionPass *llvm::createPredicateSimplifierPass() { + return new PredicateSimplifier(); +} |
