-//===-- PredicateSimplifier.cpp - Path Sensitive Simplifier -----------===//
+//===-- PredicateSimplifier.cpp - Path Sensitive Simplifier ---------------===//
//
// The LLVM Compiler Infrastructure
//
-// This file was developed by Nick Lewycky and is distributed under the
-// University of Illinois Open Source License. See LICENSE.TXT for details.
+// 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
// foo(); // unreachable
// }
//
-//===------------------------------------------------------------------===//
+//===----------------------------------------------------------------------===//
//
-// This optimization works by substituting %q for %p when protected by a
-// conditional that assures us of that fact. Properties are stored as
-// relationships between two values.
+// 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/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 <iostream>
+#include "llvm/Target/TargetData.h"
+#include "llvm/Transforms/Utils/Local.h"
+#include <algorithm>
+#include <deque>
+#include <stack>
using namespace llvm;
-typedef DominatorTree::Node DTNodeType;
+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 {
- Statistic<>
- NumVarsReplaced("predsimplify", "Number of argument substitutions");
- Statistic<>
- NumInstruction("predsimplify", "Number of instructions removed");
-
- class PropertySet;
-
- /// Similar to EquivalenceClasses, this stores the set of equivalent
- /// types. Beyond EquivalenceClasses, it allows us to specify which
- /// element will act as leader.
- template<typename ElemTy>
- class VISIBILITY_HIDDEN Synonyms {
- std::map<ElemTy, unsigned> mapping;
- std::vector<ElemTy> leaders;
- PropertySet *PS;
-
+ class DomTreeDFS {
public:
- typedef unsigned iterator;
- typedef const unsigned const_iterator;
+ class Node {
+ friend class DomTreeDFS;
+ public:
+ typedef std::vector<Node *>::iterator iterator;
+ typedef std::vector<Node *>::const_iterator const_iterator;
- Synonyms(PropertySet *PS) : PS(PS) {}
+ unsigned getDFSNumIn() const { return DFSin; }
+ unsigned getDFSNumOut() const { return DFSout; }
- // Inspection
+ BasicBlock *getBlock() const { return BB; }
- bool empty() const {
- return leaders.empty();
- }
+ iterator begin() { return Children.begin(); }
+ iterator end() { return Children.end(); }
- iterator findLeader(ElemTy e) {
- typename std::map<ElemTy, unsigned>::iterator MI = mapping.find(e);
- if (MI == mapping.end()) return 0;
+ const_iterator begin() const { return Children.begin(); }
+ const_iterator end() const { return Children.end(); }
- return MI->second;
- }
+ bool dominates(const Node *N) const {
+ return DFSin <= N->DFSin && DFSout >= N->DFSout;
+ }
- const_iterator findLeader(ElemTy e) const {
- typename std::map<ElemTy, unsigned>::const_iterator MI =
- mapping.find(e);
- if (MI == mapping.end()) return 0;
+ bool DominatedBy(const Node *N) const {
+ return N->dominates(this);
+ }
- return MI->second;
- }
+ /// 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; }
- ElemTy &getLeader(iterator I) {
- assert(I && I <= leaders.size() && "Illegal leader to get.");
- return leaders[I-1];
- }
+ private:
+ unsigned DFSin, DFSout;
+ BasicBlock *BB;
- const ElemTy &getLeader(const_iterator I) const {
- assert(I && I <= leaders.size() && "Illegal leaders to get.");
- return leaders[I-1];
- }
+ std::vector<Node *> Children;
+ };
-#ifdef DEBUG
- void debug(std::ostream &os) const {
- for (unsigned i = 1, e = leaders.size()+1; i != e; ++i) {
- os << i << ". " << *getLeader(i) << ": [";
- for (std::map<Value *, unsigned>::const_iterator
- I = mapping.begin(), E = mapping.end(); I != E; ++I) {
- if ((*I).second == i && (*I).first != leaders[i-1]) {
- os << *(*I).first << " ";
- }
+ // 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;
}
- os << "]\n";
}
+
+ 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();
- // Mutators
+ for (Node::iterator I = N->begin(), E = N->end(); I != E; ++I)
+ S.push(*I);
- /// Combine two sets referring to the same element, inserting the
- /// elements as needed. Returns a valid iterator iff two already
- /// existing disjoint synonym sets were combined. The iterator
- /// points to the no longer existing element.
- iterator unionSets(ElemTy E1, ElemTy E2);
+ delete N;
+ }
+ }
- /// Returns an iterator pointing to the synonym set containing
- /// element e. If none exists, a new one is created and returned.
- iterator findOrInsert(ElemTy e) {
- iterator I = findLeader(e);
- if (I) return I;
+ /// getRootNode - This returns the entry node for the CFG of the function.
+ Node *getRootNode() const { return Entry; }
- leaders.push_back(e);
- I = leaders.size();
- mapping[e] = I;
- return I;
+ /// 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];
}
- };
- /// Represents the set of equivalent Value*s and provides insertion
- /// and fast lookup. Also stores the set of inequality relationships.
- class PropertySet {
- /// Returns true if V1 is a better choice than V2.
- bool compare(Value *V1, Value *V2) const {
- if (isa<Constant>(V1)) {
- if (!isa<Constant>(V2)) {
- return true;
- }
- } else if (isa<Argument>(V1)) {
- if (!isa<Constant>(V2) && !isa<Argument>(V2)) {
- return true;
- }
- }
- if (Instruction *I1 = dyn_cast<Instruction>(V1)) {
- if (Instruction *I2 = dyn_cast<Instruction>(V2)) {
- BasicBlock *BB1 = I1->getParent(),
- *BB2 = I2->getParent();
- if (BB1 == BB2) {
- for (BasicBlock::const_iterator I = BB1->begin(), E = BB1->end();
- I != E; ++I) {
- if (&*I == I1) return true;
- if (&*I == I2) return false;
- }
- assert(0 && "Instructions not found in parent BasicBlock?");
- } else
- return DT->getNode(BB1)->properlyDominates(DT->getNode(BB2));
+ /// 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;
+ return false; // Not reached
}
- struct Property;
- public:
- /// Choose the canonical Value in a synonym set.
- /// Leaves the more canonical choice in V1.
- void order(Value *&V1, Value *&V2) const {
- if (compare(V2, V1)) std::swap(V1, V2);
+ 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()));
+ }
+ }
}
- PropertySet(DominatorTree *DT) : union_find(this), DT(DT) {}
+#ifndef NDEBUG
+ virtual void dump() const {
+ dump(*cerr.stream());
+ }
- Synonyms<Value *> union_find;
+ void dump(std::ostream &os) const {
+ os << "Predicate simplifier DomTreeDFS: \n";
+ dump(Entry, 0, os);
+ os << "\n\n";
+ }
- typedef std::vector<Property>::iterator PropertyIterator;
- typedef std::vector<Property>::const_iterator ConstPropertyIterator;
- typedef Synonyms<Value *>::iterator SynonymIterator;
+ void dump(Node *N, int depth, std::ostream &os) const {
+ ++depth;
+ for (int i = 0; i < depth; ++i) { os << " "; }
+ os << "[" << depth << "] ";
- enum Ops {
- EQ,
- NE
- };
+ os << N->getBlock()->getName() << " (" << N->getDFSNumIn()
+ << ", " << N->getDFSNumOut() << ")\n";
- Value *canonicalize(Value *V) const {
- Value *C = lookup(V);
- return C ? C : V;
+ for (Node::iterator I = N->begin(), E = N->end(); I != E; ++I)
+ dump(*I, depth, os);
}
+#endif
- Value *lookup(Value *V) const {
- SynonymIterator SI = union_find.findLeader(V);
- if (!SI) return NULL;
- return union_find.getLeader(SI);
- }
+ 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
+ };
- bool empty() const {
- return union_find.empty();
+ /// 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;
}
+ }
- void addEqual(Value *V1, Value *V2) {
- // If %x = 0. and %y = -0., seteq %x, %y is true, but
- // copysign(%x) is not the same as copysign(%y).
- if (V1->getType()->isFloatingPoint()) return;
+ /// 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
- order(V1, V2);
- if (isa<Constant>(V2)) return; // refuse to set false == true.
+ if ((reverse & (SLT_BIT|SGT_BIT)) == 0)
+ reverse |= (SLT_BIT|SGT_BIT);
- SynonymIterator deleted = union_find.unionSets(V1, V2);
- if (deleted) {
- SynonymIterator replacement = union_find.findLeader(V1);
- // Move Properties
- for (PropertyIterator I = Properties.begin(), E = Properties.end();
- I != E; ++I) {
- if (I->I1 == deleted) I->I1 = replacement;
- else if (I->I1 > deleted) --I->I1;
- if (I->I2 == deleted) I->I2 = replacement;
- else if (I->I2 > deleted) --I->I2;
- }
+ 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;
}
- addImpliedProperties(EQ, V1, V2);
- }
- void addNotEqual(Value *V1, Value *V2) {
- // If %x = NAN then seteq %x, %x is false.
- if (V1->getType()->isFloatingPoint()) return;
+ bool operator<(const VNPair &RHS) const {
+ if (V != RHS.V) return V < RHS.V;
+ return *Subtree < *RHS.Subtree;
+ }
- // For example, %x = setne int 0, 0 causes "0 != 0".
- if (isa<Constant>(V1) && isa<Constant>(V2)) return;
+ bool operator<(Value *RHS) const {
+ return V < RHS;
+ }
- if (findProperty(NE, V1, V2) != Properties.end())
- return; // found.
+ bool operator>(Value *RHS) const {
+ return V > RHS;
+ }
- // Add the property.
- SynonymIterator I1 = union_find.findOrInsert(V1),
- I2 = union_find.findOrInsert(V2);
+ friend bool operator<(Value *RHS, const VNPair &pair) {
+ return pair.operator>(RHS);
+ }
+ };
- // Technically this means that the block is unreachable.
- if (I1 == I2) return;
+ typedef std::vector<VNPair> VNMapType;
+ VNMapType VNMap;
- Properties.push_back(Property(NE, I1, I2));
- addImpliedProperties(NE, V1, V2);
- }
+ /// The canonical choice for value number at index.
+ std::vector<Value *> Values;
- PropertyIterator findProperty(Ops Opcode, Value *V1, Value *V2) {
- assert(Opcode != EQ && "Can't findProperty on EQ."
- "Use the lookup method instead.");
+ DomTreeDFS *DTDFS;
- SynonymIterator I1 = union_find.findLeader(V1),
- I2 = union_find.findLeader(V2);
- if (!I1 || !I2) return Properties.end();
+ public:
+#ifndef NDEBUG
+ virtual ~ValueNumbering() {}
+ virtual void dump() {
+ dump(*cerr.stream());
+ }
- return
- find(Properties.begin(), Properties.end(), Property(Opcode, I1, I2));
+ 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
- ConstPropertyIterator
- findProperty(Ops Opcode, Value *V1, Value *V2) const {
- assert(Opcode != EQ && "Can't findProperty on EQ."
- "Use the lookup method instead.");
+ /// 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);
+ }
- SynonymIterator I1 = union_find.findLeader(V1),
- I2 = union_find.findLeader(V2);
- if (!I1 || !I2) return Properties.end();
+ 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;
+ }
- return
- find(Properties.begin(), Properties.end(), Property(Opcode, I1, I2));
+ /// 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);
}
- private:
- // Represents Head OP [Tail1, Tail2, ...]
- // For example: %x != %a, %x != %b.
- struct VISIBILITY_HIDDEN Property {
- typedef SynonymIterator Iter;
+ /// 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");
- Property(Ops opcode, Iter i1, Iter i2)
- : Opcode(opcode), I1(i1), I2(i2)
- { assert(opcode != EQ && "Equality belongs in the synonym set, "
- "not a property."); }
+ Values.push_back(V);
- bool operator==(const Property &P) const {
- return (Opcode == P.Opcode) &&
- ((I1 == P.I1 && I2 == P.I2) ||
- (I1 == P.I2 && I2 == P.I1));
- }
+ 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);
- Ops Opcode;
- Iter I1, I2;
- };
+ return Values.size();
+ }
- void add(Ops Opcode, Value *V1, Value *V2, bool invert) {
- switch (Opcode) {
- case EQ:
- if (invert) addNotEqual(V1, V2);
- else addEqual(V1, V2);
- break;
- case NE:
- if (invert) addEqual(V1, V2);
- else addNotEqual(V1, V2);
- break;
- default:
- assert(0 && "Unknown property opcode.");
- }
+ /// 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];
}
- // Finds the properties implied by an equivalence and adds them too.
- // Example: ("seteq %a, %b", true, EQ) --> (%a, %b, EQ)
- // ("seteq %a, %b", false, EQ) --> (%a, %b, NE)
- void addImpliedProperties(Ops Opcode, Value *V1, Value *V2) {
- order(V1, V2);
+ /// 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 (BinaryOperator *BO = dyn_cast<BinaryOperator>(V2)) {
- switch (BO->getOpcode()) {
- case Instruction::SetEQ:
- if (ConstantBool *V1CB = dyn_cast<ConstantBool>(V1))
- add(Opcode, BO->getOperand(0), BO->getOperand(1),!V1CB->getValue());
- break;
- case Instruction::SetNE:
- if (ConstantBool *V1CB = dyn_cast<ConstantBool>(V1))
- add(Opcode, BO->getOperand(0), BO->getOperand(1), V1CB->getValue());
- break;
- case Instruction::SetLT:
- case Instruction::SetGT:
- if (V1 == ConstantBool::getTrue())
- add(Opcode, BO->getOperand(0), BO->getOperand(1), true);
- break;
- case Instruction::SetLE:
- case Instruction::SetGE:
- if (V1 == ConstantBool::getFalse())
- add(Opcode, BO->getOperand(0), BO->getOperand(1), true);
- break;
- case Instruction::And:
- if (V1 == ConstantBool::getTrue()) {
- add(Opcode, V1, BO->getOperand(0), false);
- add(Opcode, V1, BO->getOperand(1), false);
- }
- break;
- case Instruction::Or:
- if (V1 == ConstantBool::getFalse()) {
- add(Opcode, V1, BO->getOperand(0), false);
- add(Opcode, V1, BO->getOperand(1), false);
- }
- break;
- case Instruction::Xor:
- if (V1 == ConstantBool::getTrue()) {
- if (BO->getOperand(0) == V1)
- add(Opcode, ConstantBool::getFalse(), BO->getOperand(1), false);
- if (BO->getOperand(1) == V1)
- add(Opcode, ConstantBool::getFalse(), BO->getOperand(0), false);
- }
- if (V1 == ConstantBool::getFalse()) {
- if (BO->getOperand(0) == ConstantBool::getTrue())
- add(Opcode, ConstantBool::getTrue(), BO->getOperand(1), false);
- if (BO->getOperand(1) == ConstantBool::getTrue())
- add(Opcode, ConstantBool::getTrue(), BO->getOperand(0), false);
- }
- break;
- default:
- break;
- }
- } else if (SelectInst *SI = dyn_cast<SelectInst>(V2)) {
- if (Opcode != EQ && Opcode != NE) return;
+ if (unsigned n = valueNumber(V, Subtree))
+ return value(n);
+ else
+ return V;
+ }
- ConstantBool *True = ConstantBool::get(Opcode==EQ),
- *False = ConstantBool::get(Opcode!=EQ);
+ /// 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.");
- if (V1 == SI->getTrueValue())
- addEqual(SI->getCondition(), True);
- else if (V1 == SI->getFalseValue())
- addEqual(SI->getCondition(), False);
- else if (Opcode == EQ)
- assert("Result of select not equal to either value.");
- }
- }
+ // 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.
- DominatorTree *DT;
- public:
-#ifdef DEBUG
- void debug(std::ostream &os) const {
- static const char *OpcodeTable[] = { "EQ", "NE" };
+ std::vector<Value *> ToRepoint(1, V);
- union_find.debug(os);
- for (std::vector<Property>::const_iterator I = Properties.begin(),
- E = Properties.end(); I != E; ++I) {
- os << (*I).I1 << " " << OpcodeTable[(*I).Opcode] << " "
- << (*I).I2 << "\n";
+ 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);
+ }
}
- os << "\n";
- }
+
+ 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;
- std::vector<Property> Properties;
+ while (I != B && (I == E || I->V == V)) --I;
+
+ VNMap.erase(I, J);
+ }
};
- /// 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.
- class PredicateSimplifier : public FunctionPass {
+ /// 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:
- bool runOnFunction(Function &F);
- virtual void getAnalysisUsage(AnalysisUsage &AU) const;
+ InequalityGraph(ValueNumbering &VN, DomTreeDFS::Node *TreeRoot)
+ : VN(VN), TreeRoot(TreeRoot) {}
- private:
- /// Backwards - Try to replace the Use of the instruction with
- /// something simpler. This resolves a value by walking backwards
- /// through its definition and the operands of that definition to
- /// see if any values can now be solved for with the properties
- /// that are in effect now, but weren't at definition time.
- class Backwards : public InstVisitor<Backwards, Value &> {
- friend class InstVisitor<Backwards, Value &>;
- const PropertySet &KP;
-
- Value &visitSetCondInst(SetCondInst &SCI);
- Value &visitBinaryOperator(BinaryOperator &BO);
- Value &visitSelectInst(SelectInst &SI);
- Value &visitInstruction(Instruction &I);
+ 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:
- explicit Backwards(const PropertySet &KP) : KP(KP) {}
+ 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;
+ }
- Value *resolve(Value *V);
+ bool operator>(unsigned to) const {
+ return To > to;
+ }
+
+ friend bool operator<(unsigned to, const Edge &edge) {
+ return edge.operator>(to);
+ }
};
- /// Forwards - Adds new properties into PropertySet 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 with the new PropertySet.
- class Forwards : public InstVisitor<Forwards> {
- friend class InstVisitor<Forwards>;
- PredicateSimplifier *PS;
- public:
- PropertySet &KP;
+ /// 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;
- Forwards(PredicateSimplifier *PS, PropertySet &KP) : PS(PS), KP(KP) {}
+ typedef SmallVector<Edge, 4> RelationsType;
+ RelationsType Relations;
- // Tries to simplify each Instruction and add new properties to
- // the PropertySet. Returns true if it erase the instruction.
- //void visitInstruction(Instruction *I);
+ // TODO: can this idea improve performance?
+ //friend class std::vector<Node>;
+ //Node(Node &N) { RelationsType.swap(N.RelationsType); }
- void visitTerminatorInst(TerminatorInst &TI);
- void visitBranchInst(BranchInst &BI);
- void visitSwitchInst(SwitchInst &SI);
+ public:
+ typedef RelationsType::iterator iterator;
+ typedef RelationsType::const_iterator const_iterator;
- void visitAllocaInst(AllocaInst &AI);
- void visitLoadInst(LoadInst &LI);
- void visitStoreInst(StoreInst &SI);
- void visitBinaryOperator(BinaryOperator &BO);
- };
+#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
- // Used by terminator instructions to proceed from the current basic
- // block to the next. Verifies that "current" dominates "next",
- // then calls visitBasicBlock.
- void proceedToSuccessors(PropertySet &CurrentPS, BasicBlock *Current);
- void proceedToSuccessor(PropertySet &Properties, BasicBlock *Next);
+ 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;
+ }
- // Visits each instruction in the basic block.
- void visitBasicBlock(BasicBlock *Block, PropertySet &KnownProperties);
+ 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;
+ }
- // Tries to simplify each Instruction and add new properties to
- // the PropertySet.
- void visitInstruction(Instruction *I, PropertySet &);
+ if (J != E && J->To == n) {
+ edge.LV = static_cast<LatticeVal>(J->LV & R);
+ assert(validPredicate(edge.LV) && "Invalid union of lattice values.");
- DominatorTree *DT;
- bool modified;
- };
+ 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;
+ }
+ }
- RegisterPass<PredicateSimplifier> X("predsimplify",
- "Predicate Simplifier");
+ // Insert new edge at Subtree if it isn't already there.
+ if (I == E || I->To != n || Subtree != I->Subtree)
+ Relations.insert(I, edge);
+ }
+ };
- template <typename ElemTy>
- typename Synonyms<ElemTy>::iterator
- Synonyms<ElemTy>::unionSets(ElemTy E1, ElemTy E2) {
- PS->order(E1, E2);
+ private:
- iterator I1 = findLeader(E1),
- I2 = findLeader(E2);
+ std::vector<Node> Nodes;
- if (!I1 && !I2) { // neither entry is in yet
- leaders.push_back(E1);
- I1 = leaders.size();
- mapping[E1] = I1;
- mapping[E2] = I1;
- return 0;
+ 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];
}
- if (!I1 && I2) {
- mapping[E1] = I2;
- std::swap(getLeader(I2), E1);
- return 0;
- }
+ /// isRelatedBy - true iff n1 op n2
+ bool isRelatedBy(unsigned n1, unsigned n2, DomTreeDFS::Node *Subtree,
+ LatticeVal LV) {
+ if (n1 == n2) return LV & EQ_BIT;
- if (I1 && !I2) {
- mapping[E2] = I1;
- return 0;
+ 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;
}
- if (I1 == I2) return 0;
+ // 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);
+ }
+ }
+ }
+ }
- // This is the case where we have two sets, [%a1, %a2, %a3] and
- // [%p1, %p2, %p3] and someone says that %a2 == %p3. We need to
- // combine the two synsets.
+ 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);
+ }
+ }
+ }
+ }
+ }
- if (I1 > I2) --I1;
+ node(n1)->update(n2, LV1, Subtree);
+ node(n2)->update(n1, reversePredicate(LV1), Subtree);
+ }
- for (std::map<Value *, unsigned>::iterator I = mapping.begin(),
- E = mapping.end(); I != E; ++I) {
- if (I->second == I2) I->second = I1;
- else if (I->second > I2) --I->second;
+ /// 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();
}
- leaders.erase(leaders.begin() + I2 - 1);
+#ifndef NDEBUG
+ virtual ~InequalityGraph() {}
+ virtual void dump() {
+ dump(*cerr.stream());
+ }
- return I2;
- }
-}
+ void dump(std::ostream &os) {
+ for (unsigned i = 1; i <= Nodes.size(); ++i) {
+ os << i << " = {";
+ node(i)->dump(os);
+ os << "}\n";
+ }
+ }
+#endif
+ };
-FunctionPass *llvm::createPredicateSimplifierPass() {
- return new PredicateSimplifier();
-}
+ class VRPSolver;
-bool PredicateSimplifier::runOnFunction(Function &F) {
- DT = &getAnalysis<DominatorTree>();
+ /// ValueRanges tracks the known integer ranges and anti-ranges of the nodes
+ /// in the InequalityGraph.
+ class VISIBILITY_HIDDEN ValueRanges {
+ ValueNumbering &VN;
+ TargetData *TD;
- modified = false;
- PropertySet KnownProperties(DT);
- visitBasicBlock(DT->getRootNode()->getBlock(), KnownProperties);
- return modified;
-}
+ class VISIBILITY_HIDDEN ScopedRange {
+ typedef std::vector<std::pair<DomTreeDFS::Node *, ConstantRange> >
+ RangeListType;
+ RangeListType RangeList;
-void PredicateSimplifier::getAnalysisUsage(AnalysisUsage &AU) const {
- AU.addRequiredID(BreakCriticalEdgesID);
- AU.addRequired<DominatorTree>();
- AU.setPreservesCFG();
- AU.addPreservedID(BreakCriticalEdgesID);
-}
+ static bool swo(const std::pair<DomTreeDFS::Node *, ConstantRange> &LHS,
+ const std::pair<DomTreeDFS::Node *, ConstantRange> &RHS) {
+ return *LHS.first < *RHS.first;
+ }
-Value &PredicateSimplifier::Backwards::visitSetCondInst(SetCondInst &SCI) {
- Value &vBO = visitBinaryOperator(SCI);
- if (&vBO != &SCI) return vBO;
+ public:
+#ifndef NDEBUG
+ virtual ~ScopedRange() {}
+ virtual void dump() const {
+ dump(*cerr.stream());
+ }
- Value *SCI0 = resolve(SCI.getOperand(0)),
- *SCI1 = resolve(SCI.getOperand(1));
+ 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
- PropertySet::ConstPropertyIterator NE =
- KP.findProperty(PropertySet::NE, SCI0, SCI1);
+ typedef RangeListType::iterator iterator;
+ typedef RangeListType::const_iterator const_iterator;
- if (NE != KP.Properties.end()) {
- switch (SCI.getOpcode()) {
- case Instruction::SetEQ: return *ConstantBool::getFalse();
- case Instruction::SetNE: return *ConstantBool::getTrue();
- case Instruction::SetLE:
- case Instruction::SetGE:
- case Instruction::SetLT:
- case Instruction::SetGT:
- break;
- default:
- assert(0 && "Unknown opcode in SetCondInst.");
- break;
- }
- }
- return SCI;
-}
+ iterator begin() { return RangeList.begin(); }
+ iterator end() { return RangeList.end(); }
+ const_iterator begin() const { return RangeList.begin(); }
+ const_iterator end() const { return RangeList.end(); }
-Value &PredicateSimplifier::Backwards::visitBinaryOperator(BinaryOperator &BO) {
- Value *V = KP.canonicalize(&BO);
- if (V != &BO) return *V;
+ 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);
- Value *lhs = resolve(BO.getOperand(0)),
- *rhs = resolve(BO.getOperand(1));
+ while (I != E && !I->first->dominates(Subtree)) ++I;
+ return I;
+ }
- ConstantIntegral *CI1 = dyn_cast<ConstantIntegral>(lhs),
- *CI2 = dyn_cast<ConstantIntegral>(rhs);
+ 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);
- if (CI1 && CI2) return *ConstantExpr::get(BO.getOpcode(), CI1, CI2);
+ while (I != E && !I->first->dominates(Subtree)) ++I;
+ return I;
+ }
- return BO;
-}
+ 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));
+ }
+ };
-Value &PredicateSimplifier::Backwards::visitSelectInst(SelectInst &SI) {
- Value *V = KP.canonicalize(&SI);
- if (V != &SI) return *V;
+ std::vector<ScopedRange> Ranges;
- Value *Condition = resolve(SI.getCondition());
- if (ConstantBool *CB = dyn_cast<ConstantBool>(Condition))
- return *resolve(CB->getValue() ? SI.getTrueValue() : SI.getFalseValue());
- return SI;
-}
+ 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);
+ }
-Value &PredicateSimplifier::Backwards::visitInstruction(Instruction &I) {
- return *KP.canonicalize(&I);
-}
+ /// 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.");
-Value *PredicateSimplifier::Backwards::resolve(Value *V) {
- if (isa<Constant>(V) || isa<BasicBlock>(V) || KP.empty()) return V;
+ if (LV == NE)
+ return makeConstantRange(ICmpInst::ICMP_NE, CR);
- if (Instruction *I = dyn_cast<Instruction>(V)) return &visit(*I);
- return KP.canonicalize(V);
-}
+ unsigned LV_s = LV & (SGT_BIT|SLT_BIT);
+ unsigned LV_u = LV & (UGT_BIT|ULT_BIT);
+ bool hasEQ = LV & EQ_BIT;
-void PredicateSimplifier::visitBasicBlock(BasicBlock *BB,
- PropertySet &KnownProperties) {
- for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
- visitInstruction(I++, KnownProperties);
- }
-}
+ ConstantRange Range(CR.getBitWidth());
-void PredicateSimplifier::visitInstruction(Instruction *I,
- PropertySet &KnownProperties) {
- // Try to replace the whole instruction.
- Backwards resolve(KnownProperties);
- Value *V = resolve.resolve(I);
- if (V != I) {
- modified = true;
- ++NumInstruction;
- DEBUG(std::cerr << "Removing " << *I);
- I->replaceAllUsesWith(V);
- I->eraseFromParent();
- return;
- }
+ 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));
+ }
- // Try to substitute operands.
- for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
- Value *Oper = I->getOperand(i);
- Value *V = resolve.resolve(Oper);
- if (V != Oper) {
- modified = true;
- ++NumVarsReplaced;
- DEBUG(std::cerr << "Resolving " << *I);
- I->setOperand(i, V);
- DEBUG(std::cerr << "into " << *I);
- }
- }
+ 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));
+ }
- Forwards visit(this, KnownProperties);
- visit.visit(*I);
-}
+ return Range;
+ }
-void PredicateSimplifier::proceedToSuccessors(PropertySet &KP,
- BasicBlock *BBCurrent) {
- DTNodeType *Current = DT->getNode(BBCurrent);
- for (DTNodeType::iterator I = Current->begin(), E = Current->end();
- I != E; ++I) {
- PropertySet Copy(KP);
- visitBasicBlock((*I)->getBlock(), Copy);
- }
-}
+ /// 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));
+ }
+ }
+ }
-void PredicateSimplifier::proceedToSuccessor(PropertySet &KP, BasicBlock *BB) {
- visitBasicBlock(BB, KP);
-}
+#ifndef NDEBUG
+ bool isCanonical(Value *V, DomTreeDFS::Node *Subtree) {
+ return V == VN.canonicalize(V, Subtree);
+ }
+#endif
-void PredicateSimplifier::Forwards::visitTerminatorInst(TerminatorInst &TI) {
- PS->proceedToSuccessors(KP, TI.getParent());
-}
+ public:
-void PredicateSimplifier::Forwards::visitBranchInst(BranchInst &BI) {
- BasicBlock *BB = BI.getParent();
+ ValueRanges(ValueNumbering &VN, TargetData *TD) : VN(VN), TD(TD) {}
- if (BI.isUnconditional()) {
- PS->proceedToSuccessors(KP, BB);
- return;
- }
+#ifndef NDEBUG
+ virtual ~ValueRanges() {}
- Value *Condition = BI.getCondition();
+ virtual void dump() const {
+ dump(*cerr.stream());
+ }
- BasicBlock *TrueDest = BI.getSuccessor(0),
- *FalseDest = BI.getSuccessor(1);
+ 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
- if (isa<ConstantBool>(Condition) || TrueDest == FalseDest) {
- PS->proceedToSuccessors(KP, BB);
- return;
- }
+ /// range - looks up the ConstantRange associated with a value number.
+ ConstantRange range(unsigned n, DomTreeDFS::Node *Subtree) {
+ assert(VN.value(n)); // performs range checks
- DTNodeType *Node = PS->DT->getNode(BB);
- for (DTNodeType::iterator I = Node->begin(), E = Node->end(); I != E; ++I) {
- BasicBlock *Dest = (*I)->getBlock();
- PropertySet DestProperties(KP);
+ if (n <= Ranges.size()) {
+ ScopedRange::iterator I = Ranges[n-1].find(Subtree);
+ if (I != Ranges[n-1].end()) return I->second;
+ }
- if (Dest == TrueDest)
- DestProperties.addEqual(ConstantBool::getTrue(), Condition);
- else if (Dest == FalseDest)
- DestProperties.addEqual(ConstantBool::getFalse(), Condition);
+ Value *V = VN.value(n);
+ ConstantRange CR = range(V);
+ return CR;
+ }
- PS->proceedToSuccessor(DestProperties, Dest);
- }
-}
+ /// 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()));
+ }
-void PredicateSimplifier::Forwards::visitSwitchInst(SwitchInst &SI) {
- Value *Condition = SI.getCondition();
+ // 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();
+ }
- // Set the EQProperty in each of the cases BBs,
- // and the NEProperties in the default BB.
- PropertySet DefaultProperties(KP);
+ 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());
+ }
+ }
- DTNodeType *Node = PS->DT->getNode(SI.getParent());
- for (DTNodeType::iterator I = Node->begin(), E = Node->end(); I != E; ++I) {
- BasicBlock *BB = (*I)->getBlock();
+ bool isRelatedBy(unsigned n1, unsigned n2, DomTreeDFS::Node *Subtree,
+ LatticeVal LV) {
+ ConstantRange CR1 = range(n1, Subtree);
+ ConstantRange CR2 = range(n2, Subtree);
- PropertySet BBProperties(KP);
- if (BB == SI.getDefaultDest()) {
- for (unsigned i = 1, e = SI.getNumCases(); i < e; ++i)
- if (SI.getSuccessor(i) != BB)
- BBProperties.addNotEqual(Condition, SI.getCaseValue(i));
- } else if (ConstantInt *CI = SI.findCaseDest(BB)) {
- BBProperties.addEqual(Condition, CI);
+ // True iff all values in CR1 are LV to all values in CR2.
+ return isRelatedBy(CR1, CR2, LV);
}
- PS->proceedToSuccessor(BBProperties, BB);
- }
-}
-void PredicateSimplifier::Forwards::visitAllocaInst(AllocaInst &AI) {
- KP.addNotEqual(Constant::getNullValue(AI.getType()), &AI);
-}
+ void addToWorklist(Value *V, Constant *C, ICmpInst::Predicate Pred,
+ VRPSolver *VRP);
+ void markBlock(VRPSolver *VRP);
-void PredicateSimplifier::Forwards::visitLoadInst(LoadInst &LI) {
- Value *Ptr = LI.getPointerOperand();
- KP.addNotEqual(Constant::getNullValue(Ptr->getType()), Ptr);
-}
+ void mergeInto(Value **I, unsigned n, unsigned New,
+ DomTreeDFS::Node *Subtree, VRPSolver *VRP) {
+ ConstantRange CR_New = range(New, Subtree);
+ ConstantRange Merged = CR_New;
-void PredicateSimplifier::Forwards::visitStoreInst(StoreInst &SI) {
- Value *Ptr = SI.getPointerOperand();
- KP.addNotEqual(Constant::getNullValue(Ptr->getType()), Ptr);
-}
+ 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);
+ }
-void PredicateSimplifier::Forwards::visitBinaryOperator(BinaryOperator &BO) {
- Instruction::BinaryOps ops = BO.getOpcode();
+ if (Merged.isFullSet() || Merged == CR_New) return;
- switch (ops) {
- case Instruction::Div:
- case Instruction::Rem: {
- Value *Divisor = BO.getOperand(1);
- KP.addNotEqual(Constant::getNullValue(Divisor->getType()), Divisor);
- break;
+ applyRange(New, Merged, Subtree, VRP);
}
- default:
- break;
- }
+
+ 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);
+ ConstantInt *AllOnes = ConstantInt::getAllOnesValue(Ty);
+
+ switch (Opcode) {
+ default: break;
+ case Instruction::LShr:
+ case Instruction::AShr:
+ case Instruction::Shl:
+ case Instruction::Sub:
+ if (Op1 == Zero) {
+ add(BO, Op0, ICmpInst::ICMP_EQ, NewContext);
+ return;
+ }
+ break;
+ case Instruction::Or:
+ if (Op0 == AllOnes || Op1 == AllOnes) {
+ add(BO, AllOnes, ICmpInst::ICMP_EQ, NewContext);
+ return;
+ } // fall-through
+ case Instruction::Xor:
+ case Instruction::Add:
+ 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;
+ }
+ // fall-through
+ case Instruction::Mul:
+ if (Op0 == Zero || Op1 == Zero) {
+ add(BO, Zero, 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 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)) {
+ Constant *One = ConstantInt::get(Ty, 1);
+ 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((intptr_t)&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;
+
+ 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 uint* 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();
}
projects / oota-llvm.git / blobdiff