1 //===-- PredicateSimplifier.cpp - Path Sensitive Simplifier ---------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by Nick Lewycky and is distributed under the
6 // University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Path-sensitive optimizer. In a branch where x == y, replace uses of
11 // x with y. Permits further optimization, such as the elimination of
12 // the unreachable call:
14 // void test(int *p, int *q)
20 // foo(); // unreachable
23 //===----------------------------------------------------------------------===//
25 // The InequalityGraph focusses on four properties; equals, not equals,
26 // less-than and less-than-or-equals-to. The greater-than forms are also held
27 // just to allow walking from a lesser node to a greater one. These properties
28 // are stored in a lattice; LE can become LT or EQ, NE can become LT or GT.
30 // These relationships define a graph between values of the same type. Each
31 // Value is stored in a map table that retrieves the associated Node. This
32 // is how EQ relationships are stored; the map contains pointers from equal
33 // Value to the same node. The node contains a most canonical Value* form
34 // and the list of known relationships with other nodes.
36 // If two nodes are known to be inequal, then they will contain pointers to
37 // each other with an "NE" relationship. If node getNode(%x) is less than
38 // getNode(%y), then the %x node will contain <%y, GT> and %y will contain
39 // <%x, LT>. This allows us to tie nodes together into a graph like this:
43 // with four nodes representing the properties. The InequalityGraph provides
44 // querying with "isRelatedBy" and mutators "addEquality" and "addInequality".
45 // To find a relationship, we start with one of the nodes any binary search
46 // through its list to find where the relationships with the second node start.
47 // Then we iterate through those to find the first relationship that dominates
50 // To create these properties, we wait until a branch or switch instruction
51 // implies that a particular value is true (or false). The VRPSolver is
52 // responsible for analyzing the variable and seeing what new inferences
53 // can be made from each property. For example:
55 // %P = icmp ne i32* %ptr, null
57 // br i1 %a label %cond_true, label %cond_false
59 // For the true branch, the VRPSolver will start with %a EQ true and look at
60 // the definition of %a and find that it can infer that %P and %Q are both
61 // true. From %P being true, it can infer that %ptr NE null. For the false
62 // branch it can't infer anything from the "and" instruction.
64 // Besides branches, we can also infer properties from instruction that may
65 // have undefined behaviour in certain cases. For example, the dividend of
66 // a division may never be zero. After the division instruction, we may assume
67 // that the dividend is not equal to zero.
69 //===----------------------------------------------------------------------===//
71 // The ValueRanges class stores the known integer bounds of a Value. When we
72 // encounter i8 %a u< %b, the ValueRanges stores that %a = [1, 255] and
73 // %b = [0, 254]. Because we store these by Value*, you should always
74 // canonicalize through the InequalityGraph first.
76 // It never stores an empty range, because that means that the code is
77 // unreachable. It never stores a single-element range since that's an equality
78 // relationship and better stored in the InequalityGraph, nor an empty range
79 // since that is better stored in UnreachableBlocks.
81 //===----------------------------------------------------------------------===//
83 #define DEBUG_TYPE "predsimplify"
84 #include "llvm/Transforms/Scalar.h"
85 #include "llvm/Constants.h"
86 #include "llvm/DerivedTypes.h"
87 #include "llvm/Instructions.h"
88 #include "llvm/Pass.h"
89 #include "llvm/ADT/DepthFirstIterator.h"
90 #include "llvm/ADT/SetOperations.h"
91 #include "llvm/ADT/SetVector.h"
92 #include "llvm/ADT/Statistic.h"
93 #include "llvm/ADT/STLExtras.h"
94 #include "llvm/Analysis/Dominators.h"
95 #include "llvm/Analysis/ET-Forest.h"
96 #include "llvm/Support/CFG.h"
97 #include "llvm/Support/Compiler.h"
98 #include "llvm/Support/ConstantRange.h"
99 #include "llvm/Support/Debug.h"
100 #include "llvm/Support/InstVisitor.h"
101 #include "llvm/Target/TargetData.h"
102 #include "llvm/Transforms/Utils/Local.h"
106 using namespace llvm;
108 STATISTIC(NumVarsReplaced, "Number of argument substitutions");
109 STATISTIC(NumInstruction , "Number of instructions removed");
110 STATISTIC(NumSimple , "Number of simple replacements");
111 STATISTIC(NumBlocks , "Number of blocks marked unreachable");
112 STATISTIC(NumSnuggle , "Number of comparisons snuggled");
115 // SLT SGT ULT UGT EQ
116 // 0 1 0 1 0 -- GT 10
117 // 0 1 0 1 1 -- GE 11
118 // 0 1 1 0 0 -- SGTULT 12
119 // 0 1 1 0 1 -- SGEULE 13
120 // 0 1 1 1 0 -- SGT 14
121 // 0 1 1 1 1 -- SGE 15
122 // 1 0 0 1 0 -- SLTUGT 18
123 // 1 0 0 1 1 -- SLEUGE 19
124 // 1 0 1 0 0 -- LT 20
125 // 1 0 1 0 1 -- LE 21
126 // 1 0 1 1 0 -- SLT 22
127 // 1 0 1 1 1 -- SLE 23
128 // 1 1 0 1 0 -- UGT 26
129 // 1 1 0 1 1 -- UGE 27
130 // 1 1 1 0 0 -- ULT 28
131 // 1 1 1 0 1 -- ULE 29
132 // 1 1 1 1 0 -- NE 30
134 EQ_BIT = 1, UGT_BIT = 2, ULT_BIT = 4, SGT_BIT = 8, SLT_BIT = 16
137 GT = SGT_BIT | UGT_BIT,
139 LT = SLT_BIT | ULT_BIT,
141 NE = SLT_BIT | SGT_BIT | ULT_BIT | UGT_BIT,
142 SGTULT = SGT_BIT | ULT_BIT,
143 SGEULE = SGTULT | EQ_BIT,
144 SLTUGT = SLT_BIT | UGT_BIT,
145 SLEUGE = SLTUGT | EQ_BIT,
146 ULT = SLT_BIT | SGT_BIT | ULT_BIT,
147 UGT = SLT_BIT | SGT_BIT | UGT_BIT,
148 SLT = SLT_BIT | ULT_BIT | UGT_BIT,
149 SGT = SGT_BIT | ULT_BIT | UGT_BIT,
156 static bool validPredicate(LatticeVal LV) {
158 case GT: case GE: case LT: case LE: case NE:
159 case SGTULT: case SGT: case SGEULE:
160 case SLTUGT: case SLT: case SLEUGE:
162 case SLE: case SGE: case ULE: case UGE:
169 /// reversePredicate - reverse the direction of the inequality
170 static LatticeVal reversePredicate(LatticeVal LV) {
171 unsigned reverse = LV ^ (SLT_BIT|SGT_BIT|ULT_BIT|UGT_BIT); //preserve EQ_BIT
173 if ((reverse & (SLT_BIT|SGT_BIT)) == 0)
174 reverse |= (SLT_BIT|SGT_BIT);
176 if ((reverse & (ULT_BIT|UGT_BIT)) == 0)
177 reverse |= (ULT_BIT|UGT_BIT);
179 LatticeVal Rev = static_cast<LatticeVal>(reverse);
180 assert(validPredicate(Rev) && "Failed reversing predicate.");
184 /// This is a StrictWeakOrdering predicate that sorts ETNodes by how many
185 /// descendants they have. With this, you can iterate through a list sorted
186 /// by this operation and the first matching entry is the most specific
187 /// match for your basic block. The order provided is stable; ETNodes with
188 /// the same number of children are sorted by pointer address.
189 struct VISIBILITY_HIDDEN OrderByDominance {
190 bool operator()(const ETNode *LHS, const ETNode *RHS) const {
191 unsigned LHS_spread = LHS->getDFSNumOut() - LHS->getDFSNumIn();
192 unsigned RHS_spread = RHS->getDFSNumOut() - RHS->getDFSNumIn();
193 if (LHS_spread != RHS_spread) return LHS_spread < RHS_spread;
194 else return LHS < RHS;
198 /// The InequalityGraph stores the relationships between values.
199 /// Each Value in the graph is assigned to a Node. Nodes are pointer
200 /// comparable for equality. The caller is expected to maintain the logical
201 /// consistency of the system.
203 /// The InequalityGraph class may invalidate Node*s after any mutator call.
204 /// @brief The InequalityGraph stores the relationships between values.
205 class VISIBILITY_HIDDEN InequalityGraph {
208 InequalityGraph(); // DO NOT IMPLEMENT
209 InequalityGraph(InequalityGraph &); // DO NOT IMPLEMENT
211 explicit InequalityGraph(ETNode *TreeRoot) : TreeRoot(TreeRoot) {}
215 /// An Edge is contained inside a Node making one end of the edge implicit
216 /// and contains a pointer to the other end. The edge contains a lattice
217 /// value specifying the relationship and an ETNode specifying the root
218 /// in the dominator tree to which this edge applies.
219 class VISIBILITY_HIDDEN Edge {
221 Edge(unsigned T, LatticeVal V, ETNode *ST)
222 : To(T), LV(V), Subtree(ST) {}
228 bool operator<(const Edge &edge) const {
229 if (To != edge.To) return To < edge.To;
230 else return OrderByDominance()(Subtree, edge.Subtree);
232 bool operator<(unsigned to) const {
237 /// A single node in the InequalityGraph. This stores the canonical Value
238 /// for the node, as well as the relationships with the neighbours.
240 /// @brief A single node in the InequalityGraph.
241 class VISIBILITY_HIDDEN Node {
242 friend class InequalityGraph;
244 typedef SmallVector<Edge, 4> RelationsType;
245 RelationsType Relations;
249 // TODO: can this idea improve performance?
250 //friend class std::vector<Node>;
251 //Node(Node &N) { RelationsType.swap(N.RelationsType); }
254 typedef RelationsType::iterator iterator;
255 typedef RelationsType::const_iterator const_iterator;
257 Node(Value *V) : Canonical(V) {}
263 virtual void dump() const {
264 dump(*cerr.stream());
267 void dump(std::ostream &os) const {
268 os << *getValue() << ":\n";
269 for (Node::const_iterator NI = begin(), NE = end(); NI != NE; ++NI) {
270 static const std::string names[32] =
271 { "000000", "000001", "000002", "000003", "000004", "000005",
272 "000006", "000007", "000008", "000009", " >", " >=",
273 " s>u<", "s>=u<=", " s>", " s>=", "000016", "000017",
274 " s<u>", "s<=u>=", " <", " <=", " s<", " s<=",
275 "000024", "000025", " u>", " u>=", " u<", " u<=",
277 os << " " << names[NI->LV] << " " << NI->To
278 << " (" << NI->Subtree->getDFSNumIn() << ")\n";
284 iterator begin() { return Relations.begin(); }
285 iterator end() { return Relations.end(); }
286 const_iterator begin() const { return Relations.begin(); }
287 const_iterator end() const { return Relations.end(); }
289 iterator find(unsigned n, ETNode *Subtree) {
291 for (iterator I = std::lower_bound(begin(), E, n);
292 I != E && I->To == n; ++I) {
293 if (Subtree->DominatedBy(I->Subtree))
299 const_iterator find(unsigned n, ETNode *Subtree) const {
300 const_iterator E = end();
301 for (const_iterator I = std::lower_bound(begin(), E, n);
302 I != E && I->To == n; ++I) {
303 if (Subtree->DominatedBy(I->Subtree))
309 Value *getValue() const
314 /// Updates the lattice value for a given node. Create a new entry if
315 /// one doesn't exist, otherwise it merges the values. The new lattice
316 /// value must not be inconsistent with any previously existing value.
317 void update(unsigned n, LatticeVal R, ETNode *Subtree) {
318 assert(validPredicate(R) && "Invalid predicate.");
319 iterator I = find(n, Subtree);
321 Edge edge(n, R, Subtree);
322 iterator Insert = std::lower_bound(begin(), end(), edge);
323 Relations.insert(Insert, edge);
325 LatticeVal LV = static_cast<LatticeVal>(I->LV & R);
326 assert(validPredicate(LV) && "Invalid union of lattice values.");
328 if (Subtree != I->Subtree) {
329 assert(Subtree->DominatedBy(I->Subtree) &&
330 "Find returned subtree that doesn't apply.");
332 Edge edge(n, R, Subtree);
333 iterator Insert = std::lower_bound(begin(), end(), edge);
334 Relations.insert(Insert, edge); // invalidates I
335 I = find(n, Subtree);
338 // Also, we have to tighten any edge that Subtree dominates.
339 for (iterator B = begin(); I->To == n; --I) {
340 if (I->Subtree->DominatedBy(Subtree)) {
341 LatticeVal LV = static_cast<LatticeVal>(I->LV & R);
342 assert(validPredicate(LV) && "Invalid union of lattice values.");
353 struct VISIBILITY_HIDDEN NodeMapEdge {
358 NodeMapEdge(Value *V, unsigned index, ETNode *Subtree)
359 : V(V), index(index), Subtree(Subtree) {}
361 bool operator==(const NodeMapEdge &RHS) const {
363 Subtree == RHS.Subtree;
366 bool operator<(const NodeMapEdge &RHS) const {
367 if (V != RHS.V) return V < RHS.V;
368 return OrderByDominance()(Subtree, RHS.Subtree);
371 bool operator<(Value *RHS) const {
376 typedef std::vector<NodeMapEdge> NodeMapType;
379 std::vector<Node> Nodes;
382 /// node - returns the node object at a given index retrieved from getNode.
383 /// Index zero is reserved and may not be passed in here. The pointer
384 /// returned is valid until the next call to newNode or getOrInsertNode.
385 Node *node(unsigned index) {
386 assert(index != 0 && "Zero index is reserved for not found.");
387 assert(index <= Nodes.size() && "Index out of range.");
388 return &Nodes[index-1];
391 /// Returns the node currently representing Value V, or zero if no such
393 unsigned getNode(Value *V, ETNode *Subtree) {
394 NodeMapType::iterator E = NodeMap.end();
395 NodeMapEdge Edge(V, 0, Subtree);
396 NodeMapType::iterator I = std::lower_bound(NodeMap.begin(), E, Edge);
397 while (I != E && I->V == V) {
398 if (Subtree->DominatedBy(I->Subtree))
405 /// getOrInsertNode - always returns a valid node index, creating a node
406 /// to match the Value if needed.
407 unsigned getOrInsertNode(Value *V, ETNode *Subtree) {
408 if (unsigned n = getNode(V, Subtree))
414 /// newNode - creates a new node for a given Value and returns the index.
415 unsigned newNode(Value *V) {
416 Nodes.push_back(Node(V));
418 NodeMapEdge MapEntry = NodeMapEdge(V, Nodes.size(), TreeRoot);
419 assert(!std::binary_search(NodeMap.begin(), NodeMap.end(), MapEntry) &&
420 "Attempt to create a duplicate Node.");
421 NodeMap.insert(std::lower_bound(NodeMap.begin(), NodeMap.end(),
422 MapEntry), MapEntry);
423 return MapEntry.index;
426 /// If the Value is in the graph, return the canonical form. Otherwise,
427 /// return the original Value.
428 Value *canonicalize(Value *V, ETNode *Subtree) {
429 if (isa<Constant>(V)) return V;
431 if (unsigned n = getNode(V, Subtree))
432 return node(n)->getValue();
437 /// isRelatedBy - true iff n1 op n2
438 bool isRelatedBy(unsigned n1, unsigned n2, ETNode *Subtree, LatticeVal LV) {
439 if (n1 == n2) return LV & EQ_BIT;
442 Node::iterator I = N1->find(n2, Subtree), E = N1->end();
443 if (I != E) return (I->LV & LV) == I->LV;
448 // The add* methods assume that your input is logically valid and may
449 // assertion-fail or infinitely loop if you attempt a contradiction.
451 void addEquality(unsigned n, Value *V, ETNode *Subtree) {
452 assert(canonicalize(node(n)->getValue(), Subtree) == node(n)->getValue()
453 && "Node's 'canonical' choice isn't best within this subtree.");
455 // Suppose that we are given "%x -> node #1 (%y)". The problem is that
456 // we may already have "%z -> node #2 (%x)" somewhere above us in the
457 // graph. We need to find those edges and add "%z -> node #1 (%y)"
458 // to keep the lookups canonical.
460 std::vector<Value *> ToRepoint;
461 ToRepoint.push_back(V);
463 if (unsigned Conflict = getNode(V, Subtree)) {
464 for (NodeMapType::iterator I = NodeMap.begin(), E = NodeMap.end();
466 if (I->index == Conflict && Subtree->DominatedBy(I->Subtree))
467 ToRepoint.push_back(I->V);
471 for (std::vector<Value *>::iterator VI = ToRepoint.begin(),
472 VE = ToRepoint.end(); VI != VE; ++VI) {
475 // XXX: review this code. This may be doing too many insertions.
476 NodeMapEdge Edge(V, n, Subtree);
477 NodeMapType::iterator E = NodeMap.end();
478 NodeMapType::iterator I = std::lower_bound(NodeMap.begin(), E, Edge);
479 if (I == E || I->V != V || I->Subtree != Subtree) {
481 NodeMap.insert(I, Edge);
482 } else if (I != E && I->V == V && I->Subtree == Subtree) {
483 // Update best choice
489 if (isa<Constant>(V)) {
490 if (isa<Constant>(N->getValue())) {
491 assert(V == N->getValue() && "Constant equals different constant?");
498 /// addInequality - Sets n1 op n2.
499 /// It is also an error to call this on an inequality that is already true.
500 void addInequality(unsigned n1, unsigned n2, ETNode *Subtree,
502 assert(n1 != n2 && "A node can't be inequal to itself.");
505 assert(!isRelatedBy(n1, n2, Subtree, reversePredicate(LV1)) &&
506 "Contradictory inequality.");
511 // Suppose we're adding %n1 < %n2. Find all the %a < %n1 and
512 // add %a < %n2 too. This keeps the graph fully connected.
514 // Break up the relationship into signed and unsigned comparison parts.
515 // If the signed parts of %a op1 %n1 match that of %n1 op2 %n2, and
516 // op1 and op2 aren't NE, then add %a op3 %n2. The new relationship
517 // should have the EQ_BIT iff it's set for both op1 and op2.
519 unsigned LV1_s = LV1 & (SLT_BIT|SGT_BIT);
520 unsigned LV1_u = LV1 & (ULT_BIT|UGT_BIT);
522 for (Node::iterator I = N1->begin(), E = N1->end(); I != E; ++I) {
523 if (I->LV != NE && I->To != n2) {
525 ETNode *Local_Subtree = NULL;
526 if (Subtree->DominatedBy(I->Subtree))
527 Local_Subtree = Subtree;
528 else if (I->Subtree->DominatedBy(Subtree))
529 Local_Subtree = I->Subtree;
532 unsigned new_relationship = 0;
533 LatticeVal ILV = reversePredicate(I->LV);
534 unsigned ILV_s = ILV & (SLT_BIT|SGT_BIT);
535 unsigned ILV_u = ILV & (ULT_BIT|UGT_BIT);
537 if (LV1_s != (SLT_BIT|SGT_BIT) && ILV_s == LV1_s)
538 new_relationship |= ILV_s;
539 if (LV1_u != (ULT_BIT|UGT_BIT) && ILV_u == LV1_u)
540 new_relationship |= ILV_u;
542 if (new_relationship) {
543 if ((new_relationship & (SLT_BIT|SGT_BIT)) == 0)
544 new_relationship |= (SLT_BIT|SGT_BIT);
545 if ((new_relationship & (ULT_BIT|UGT_BIT)) == 0)
546 new_relationship |= (ULT_BIT|UGT_BIT);
547 if ((LV1 & EQ_BIT) && (ILV & EQ_BIT))
548 new_relationship |= EQ_BIT;
550 LatticeVal NewLV = static_cast<LatticeVal>(new_relationship);
552 node(I->To)->update(n2, NewLV, Local_Subtree);
553 N2->update(I->To, reversePredicate(NewLV), Local_Subtree);
559 for (Node::iterator I = N2->begin(), E = N2->end(); I != E; ++I) {
560 if (I->LV != NE && I->To != n1) {
561 ETNode *Local_Subtree = NULL;
562 if (Subtree->DominatedBy(I->Subtree))
563 Local_Subtree = Subtree;
564 else if (I->Subtree->DominatedBy(Subtree))
565 Local_Subtree = I->Subtree;
568 unsigned new_relationship = 0;
569 unsigned ILV_s = I->LV & (SLT_BIT|SGT_BIT);
570 unsigned ILV_u = I->LV & (ULT_BIT|UGT_BIT);
572 if (LV1_s != (SLT_BIT|SGT_BIT) && ILV_s == LV1_s)
573 new_relationship |= ILV_s;
575 if (LV1_u != (ULT_BIT|UGT_BIT) && ILV_u == LV1_u)
576 new_relationship |= ILV_u;
578 if (new_relationship) {
579 if ((new_relationship & (SLT_BIT|SGT_BIT)) == 0)
580 new_relationship |= (SLT_BIT|SGT_BIT);
581 if ((new_relationship & (ULT_BIT|UGT_BIT)) == 0)
582 new_relationship |= (ULT_BIT|UGT_BIT);
583 if ((LV1 & EQ_BIT) && (I->LV & EQ_BIT))
584 new_relationship |= EQ_BIT;
586 LatticeVal NewLV = static_cast<LatticeVal>(new_relationship);
588 N1->update(I->To, NewLV, Local_Subtree);
589 node(I->To)->update(n1, reversePredicate(NewLV), Local_Subtree);
596 N1->update(n2, LV1, Subtree);
597 N2->update(n1, reversePredicate(LV1), Subtree);
600 /// remove - Removes a Value from the graph. If the value is the canonical
601 /// choice for a Node, destroys the Node from the graph deleting all edges
602 /// to and from it. This method does not renumber the nodes.
603 void remove(Value *V) {
604 for (unsigned i = 0; i < NodeMap.size();) {
605 NodeMapType::iterator I = NodeMap.begin()+i;
607 Node *N = node(I->index);
608 if (node(I->index)->getValue() == V) {
609 for (Node::iterator NI = N->begin(), NE = N->end(); NI != NE; ++NI){
610 Node::iterator Iter = node(NI->To)->find(I->index, TreeRoot);
612 node(NI->To)->Relations.erase(Iter);
613 Iter = node(NI->To)->find(I->index, TreeRoot);
614 } while (Iter != node(NI->To)->end());
618 N->Relations.clear();
625 virtual ~InequalityGraph() {}
626 virtual void dump() {
627 dump(*cerr.stream());
630 void dump(std::ostream &os) {
631 std::set<Node *> VisitedNodes;
632 for (NodeMapType::const_iterator I = NodeMap.begin(), E = NodeMap.end();
634 Node *N = node(I->index);
635 os << *I->V << " == " << I->index
636 << "(" << I->Subtree->getDFSNumIn() << ")\n";
637 if (VisitedNodes.insert(N).second) {
638 os << I->index << ". ";
639 if (!N->getValue()) os << "(deleted node)\n";
649 /// ValueRanges tracks the known integer ranges and anti-ranges of the nodes
650 /// in the InequalityGraph.
651 class VISIBILITY_HIDDEN ValueRanges {
653 /// A ScopedRange ties an InequalityGraph node with a ConstantRange under
654 /// the scope of a rooted subtree in the dominator tree.
655 class VISIBILITY_HIDDEN ScopedRange {
657 ScopedRange(Value *V, ConstantRange CR, ETNode *ST)
658 : V(V), CR(CR), Subtree(ST) {}
664 bool operator<(const ScopedRange &range) const {
665 if (V != range.V) return V < range.V;
666 else return OrderByDominance()(Subtree, range.Subtree);
669 bool operator<(const Value *value) const {
676 std::vector<ScopedRange> Ranges;
677 typedef std::vector<ScopedRange>::iterator iterator;
679 // XXX: this is a copy of the code in InequalityGraph::Node. Perhaps a
680 // intrusive domtree-scoped container is in order?
682 iterator begin() { return Ranges.begin(); }
683 iterator end() { return Ranges.end(); }
685 iterator find(Value *V, ETNode *Subtree) {
687 for (iterator I = std::lower_bound(begin(), E, V);
688 I != E && I->V == V; ++I) {
689 if (Subtree->DominatedBy(I->Subtree))
695 void update(Value *V, ConstantRange CR, ETNode *Subtree) {
696 assert(!CR.isEmptySet() && "Empty ConstantRange!");
697 if (CR.isFullSet()) return;
699 iterator I = find(V, Subtree);
701 ScopedRange range(V, CR, Subtree);
702 iterator Insert = std::lower_bound(begin(), end(), range);
703 Ranges.insert(Insert, range);
705 CR = CR.intersectWith(I->CR);
706 assert(!CR.isEmptySet() && "Empty intersection of ConstantRanges!");
709 if (Subtree != I->Subtree) {
710 assert(Subtree->DominatedBy(I->Subtree) &&
711 "Find returned subtree that doesn't apply.");
713 ScopedRange range(V, CR, Subtree);
714 iterator Insert = std::lower_bound(begin(), end(), range);
715 Ranges.insert(Insert, range); // invalidates I
716 I = find(V, Subtree);
719 // Also, we have to tighten any edge that Subtree dominates.
720 for (iterator B = begin(); I->V == V; --I) {
721 if (I->Subtree->DominatedBy(Subtree)) {
722 I->CR = CR.intersectWith(I->CR);
723 assert(!I->CR.isEmptySet() &&
724 "Empty intersection of ConstantRanges!");
732 /// range - Creates a ConstantRange representing the set of all values
733 /// that match the ICmpInst::Predicate with any of the values in CR.
734 ConstantRange range(ICmpInst::Predicate ICmpOpcode,
735 const ConstantRange &CR) {
736 uint32_t W = CR.getBitWidth();
737 switch (ICmpOpcode) {
738 default: assert(!"Invalid ICmp opcode to range()");
739 case ICmpInst::ICMP_EQ:
740 return ConstantRange(CR.getLower(), CR.getUpper());
741 case ICmpInst::ICMP_NE:
742 if (CR.isSingleElement())
743 return ConstantRange(CR.getUpper(), CR.getLower());
744 return ConstantRange(W);
745 case ICmpInst::ICMP_ULT:
746 return ConstantRange(APInt::getMinValue(W), CR.getUnsignedMax());
747 case ICmpInst::ICMP_SLT:
748 return ConstantRange(APInt::getSignedMinValue(W), CR.getSignedMax());
749 case ICmpInst::ICMP_ULE: {
750 APInt UMax = CR.getUnsignedMax();
751 if (UMax == APInt::getMaxValue(W))
752 return ConstantRange(W);
753 return ConstantRange(APInt::getMinValue(W), UMax + 1);
755 case ICmpInst::ICMP_SLE: {
756 APInt SMax = CR.getSignedMax();
757 if (SMax == APInt::getSignedMaxValue(W) ||
758 SMax + 1 == APInt::getSignedMaxValue(W))
759 return ConstantRange(W);
760 return ConstantRange(APInt::getSignedMinValue(W), SMax + 1);
762 case ICmpInst::ICMP_UGT:
763 return ConstantRange(CR.getUnsignedMin() + 1,
764 APInt::getMaxValue(W) + 1);
765 case ICmpInst::ICMP_SGT:
766 return ConstantRange(CR.getSignedMin() + 1,
767 APInt::getSignedMaxValue(W) + 1);
768 case ICmpInst::ICMP_UGE: {
769 APInt UMin = CR.getUnsignedMin();
770 if (UMin == APInt::getMinValue(W))
771 return ConstantRange(W);
772 return ConstantRange(UMin, APInt::getMaxValue(W) + 1);
774 case ICmpInst::ICMP_SGE: {
775 APInt SMin = CR.getSignedMin();
776 if (SMin == APInt::getSignedMinValue(W))
777 return ConstantRange(W);
778 return ConstantRange(SMin, APInt::getSignedMaxValue(W) + 1);
783 /// create - Creates a ConstantRange that matches the given LatticeVal
784 /// relation with a given integer.
785 ConstantRange create(LatticeVal LV, const ConstantRange &CR) {
786 assert(!CR.isEmptySet() && "Can't deal with empty set.");
789 return range(ICmpInst::ICMP_NE, CR);
791 unsigned LV_s = LV & (SGT_BIT|SLT_BIT);
792 unsigned LV_u = LV & (UGT_BIT|ULT_BIT);
793 bool hasEQ = LV & EQ_BIT;
795 ConstantRange Range(CR.getBitWidth());
797 if (LV_s == SGT_BIT) {
798 Range = Range.intersectWith(range(
799 hasEQ ? ICmpInst::ICMP_SGE : ICmpInst::ICMP_SGT, CR));
800 } else if (LV_s == SLT_BIT) {
801 Range = Range.intersectWith(range(
802 hasEQ ? ICmpInst::ICMP_SLE : ICmpInst::ICMP_SLT, CR));
805 if (LV_u == UGT_BIT) {
806 Range = Range.intersectWith(range(
807 hasEQ ? ICmpInst::ICMP_UGE : ICmpInst::ICMP_UGT, CR));
808 } else if (LV_u == ULT_BIT) {
809 Range = Range.intersectWith(range(
810 hasEQ ? ICmpInst::ICMP_ULE : ICmpInst::ICMP_ULT, CR));
817 bool isCanonical(Value *V, ETNode *Subtree, VRPSolver *VRP);
822 explicit ValueRanges(TargetData *TD) : TD(TD) {}
824 // rangeFromValue - converts a Value into a range. If the value is a
825 // constant it constructs the single element range, otherwise it performs
826 // a lookup. The width W must be retrieved from typeToWidth and may not
828 ConstantRange rangeFromValue(Value *V, ETNode *Subtree, uint32_t W) {
829 if (ConstantInt *C = dyn_cast<ConstantInt>(V)) {
830 return ConstantRange(C->getValue());
831 } else if (isa<ConstantPointerNull>(V)) {
832 return ConstantRange(APInt::getNullValue(W));
834 iterator I = find(V, Subtree);
838 return ConstantRange(W);
841 // typeToWidth - returns the number of bits necessary to store a value of
842 // this type, or zero if unknown.
843 uint32_t typeToWidth(const Type *Ty) const {
845 return TD->getTypeSizeInBits(Ty);
847 if (const IntegerType *ITy = dyn_cast<IntegerType>(Ty))
848 return ITy->getBitWidth();
853 bool isRelatedBy(Value *V1, Value *V2, ETNode *Subtree, LatticeVal LV) {
854 uint32_t W = typeToWidth(V1->getType());
855 if (!W) return false;
857 ConstantRange CR1 = rangeFromValue(V1, Subtree, W);
858 ConstantRange CR2 = rangeFromValue(V2, Subtree, W);
860 // True iff all values in CR1 are LV to all values in CR2.
862 default: assert(!"Impossible lattice value!");
864 return CR1.intersectWith(CR2).isEmptySet();
866 return CR1.getUnsignedMax().ult(CR2.getUnsignedMin());
868 return CR1.getUnsignedMax().ule(CR2.getUnsignedMin());
870 return CR1.getUnsignedMin().ugt(CR2.getUnsignedMax());
872 return CR1.getUnsignedMin().uge(CR2.getUnsignedMax());
874 return CR1.getSignedMax().slt(CR2.getSignedMin());
876 return CR1.getSignedMax().sle(CR2.getSignedMin());
878 return CR1.getSignedMin().sgt(CR2.getSignedMax());
880 return CR1.getSignedMin().sge(CR2.getSignedMax());
882 return CR1.getUnsignedMax().ult(CR2.getUnsignedMin()) &&
883 CR1.getSignedMax().slt(CR2.getUnsignedMin());
885 return CR1.getUnsignedMax().ule(CR2.getUnsignedMin()) &&
886 CR1.getSignedMax().sle(CR2.getUnsignedMin());
888 return CR1.getUnsignedMin().ugt(CR2.getUnsignedMax()) &&
889 CR1.getSignedMin().sgt(CR2.getSignedMax());
891 return CR1.getUnsignedMin().uge(CR2.getUnsignedMax()) &&
892 CR1.getSignedMin().sge(CR2.getSignedMax());
894 return CR1.getSignedMax().slt(CR2.getSignedMin()) &&
895 CR1.getUnsignedMin().ugt(CR2.getUnsignedMax());
897 return CR1.getSignedMax().sle(CR2.getSignedMin()) &&
898 CR1.getUnsignedMin().uge(CR2.getUnsignedMax());
900 return CR1.getSignedMin().sgt(CR2.getSignedMax()) &&
901 CR1.getUnsignedMax().ult(CR2.getUnsignedMin());
903 return CR1.getSignedMin().sge(CR2.getSignedMax()) &&
904 CR1.getUnsignedMax().ule(CR2.getUnsignedMin());
908 void addToWorklist(Value *V, Constant *C, ICmpInst::Predicate Pred,
910 void markBlock(VRPSolver *VRP);
912 void mergeInto(Value **I, unsigned n, Value *New, ETNode *Subtree,
914 assert(isCanonical(New, Subtree, VRP) && "Best choice not canonical?");
916 uint32_t W = typeToWidth(New->getType());
919 ConstantRange CR_New = rangeFromValue(New, Subtree, W);
920 ConstantRange Merged = CR_New;
922 for (; n != 0; ++I, --n) {
923 ConstantRange CR_Kill = rangeFromValue(*I, Subtree, W);
924 if (CR_Kill.isFullSet()) continue;
925 Merged = Merged.intersectWith(CR_Kill);
928 if (Merged.isFullSet() || Merged == CR_New) return;
930 applyRange(New, Merged, Subtree, VRP);
933 void applyRange(Value *V, const ConstantRange &CR, ETNode *Subtree,
935 assert(isCanonical(V, Subtree, VRP) && "Value not canonical.");
937 if (const APInt *I = CR.getSingleElement()) {
938 const Type *Ty = V->getType();
939 if (Ty->isInteger()) {
940 addToWorklist(V, ConstantInt::get(*I), ICmpInst::ICMP_EQ, VRP);
942 } else if (const PointerType *PTy = dyn_cast<PointerType>(Ty)) {
943 assert(*I == 0 && "Pointer is null but not zero?");
944 addToWorklist(V, ConstantPointerNull::get(PTy),
945 ICmpInst::ICMP_EQ, VRP);
950 ConstantRange Merged = CR.intersectWith(
951 rangeFromValue(V, Subtree, CR.getBitWidth()));
952 if (Merged.isEmptySet()) {
957 update(V, Merged, Subtree);
960 void addNotEquals(Value *V1, Value *V2, ETNode *Subtree, VRPSolver *VRP) {
961 uint32_t W = typeToWidth(V1->getType());
964 ConstantRange CR1 = rangeFromValue(V1, Subtree, W);
965 ConstantRange CR2 = rangeFromValue(V2, Subtree, W);
967 if (const APInt *I = CR1.getSingleElement()) {
968 if (CR2.isFullSet()) {
969 ConstantRange NewCR2(CR1.getUpper(), CR1.getLower());
970 applyRange(V2, NewCR2, Subtree, VRP);
971 } else if (*I == CR2.getLower()) {
972 APInt NewLower = CR2.getLower() + 1,
973 NewUpper = CR2.getUpper();
974 if (NewLower == NewUpper)
975 NewLower = NewUpper = APInt::getMinValue(W);
977 ConstantRange NewCR2(NewLower, NewUpper);
978 applyRange(V2, NewCR2, Subtree, VRP);
979 } else if (*I == CR2.getUpper() - 1) {
980 APInt NewLower = CR2.getLower(),
981 NewUpper = CR2.getUpper() - 1;
982 if (NewLower == NewUpper)
983 NewLower = NewUpper = APInt::getMinValue(W);
985 ConstantRange NewCR2(NewLower, NewUpper);
986 applyRange(V2, NewCR2, Subtree, VRP);
990 if (const APInt *I = CR2.getSingleElement()) {
991 if (CR1.isFullSet()) {
992 ConstantRange NewCR1(CR2.getUpper(), CR2.getLower());
993 applyRange(V1, NewCR1, Subtree, VRP);
994 } else if (*I == CR1.getLower()) {
995 APInt NewLower = CR1.getLower() + 1,
996 NewUpper = CR1.getUpper();
997 if (NewLower == NewUpper)
998 NewLower = NewUpper = APInt::getMinValue(W);
1000 ConstantRange NewCR1(NewLower, NewUpper);
1001 applyRange(V1, NewCR1, Subtree, VRP);
1002 } else if (*I == CR1.getUpper() - 1) {
1003 APInt NewLower = CR1.getLower(),
1004 NewUpper = CR1.getUpper() - 1;
1005 if (NewLower == NewUpper)
1006 NewLower = NewUpper = APInt::getMinValue(W);
1008 ConstantRange NewCR1(NewLower, NewUpper);
1009 applyRange(V1, NewCR1, Subtree, VRP);
1014 void addInequality(Value *V1, Value *V2, ETNode *Subtree, LatticeVal LV,
1016 assert(!isRelatedBy(V1, V2, Subtree, LV) && "Asked to do useless work.");
1018 assert(isCanonical(V1, Subtree, VRP) && "Value not canonical.");
1019 assert(isCanonical(V2, Subtree, VRP) && "Value not canonical.");
1022 addNotEquals(V1, V2, Subtree, VRP);
1026 uint32_t W = typeToWidth(V1->getType());
1029 ConstantRange CR1 = rangeFromValue(V1, Subtree, W);
1030 ConstantRange CR2 = rangeFromValue(V2, Subtree, W);
1032 if (!CR1.isSingleElement()) {
1033 ConstantRange NewCR1 = CR1.intersectWith(create(LV, CR2));
1035 applyRange(V1, NewCR1, Subtree, VRP);
1038 if (!CR2.isSingleElement()) {
1039 ConstantRange NewCR2 = CR2.intersectWith(create(reversePredicate(LV),
1042 applyRange(V2, NewCR2, Subtree, VRP);
1047 /// UnreachableBlocks keeps tracks of blocks that are for one reason or
1048 /// another discovered to be unreachable. This is used to cull the graph when
1049 /// analyzing instructions, and to mark blocks with the "unreachable"
1050 /// terminator instruction after the function has executed.
1051 class VISIBILITY_HIDDEN UnreachableBlocks {
1053 std::vector<BasicBlock *> DeadBlocks;
1056 /// mark - mark a block as dead
1057 void mark(BasicBlock *BB) {
1058 std::vector<BasicBlock *>::iterator E = DeadBlocks.end();
1059 std::vector<BasicBlock *>::iterator I =
1060 std::lower_bound(DeadBlocks.begin(), E, BB);
1062 if (I == E || *I != BB) DeadBlocks.insert(I, BB);
1065 /// isDead - returns whether a block is known to be dead already
1066 bool isDead(BasicBlock *BB) {
1067 std::vector<BasicBlock *>::iterator E = DeadBlocks.end();
1068 std::vector<BasicBlock *>::iterator I =
1069 std::lower_bound(DeadBlocks.begin(), E, BB);
1071 return I != E && *I == BB;
1074 /// kill - replace the dead blocks' terminator with an UnreachableInst.
1076 bool modified = false;
1077 for (std::vector<BasicBlock *>::iterator I = DeadBlocks.begin(),
1078 E = DeadBlocks.end(); I != E; ++I) {
1079 BasicBlock *BB = *I;
1081 DOUT << "unreachable block: " << BB->getName() << "\n";
1083 for (succ_iterator SI = succ_begin(BB), SE = succ_end(BB);
1085 BasicBlock *Succ = *SI;
1086 Succ->removePredecessor(BB);
1089 TerminatorInst *TI = BB->getTerminator();
1090 TI->replaceAllUsesWith(UndefValue::get(TI->getType()));
1091 TI->eraseFromParent();
1092 new UnreachableInst(BB);
1101 /// VRPSolver keeps track of how changes to one variable affect other
1102 /// variables, and forwards changes along to the InequalityGraph. It
1103 /// also maintains the correct choice for "canonical" in the IG.
1104 /// @brief VRPSolver calculates inferences from a new relationship.
1105 class VISIBILITY_HIDDEN VRPSolver {
1107 friend class ValueRanges;
1111 ICmpInst::Predicate Op;
1113 BasicBlock *ContextBB;
1114 Instruction *ContextInst;
1116 std::deque<Operation> WorkList;
1118 InequalityGraph &IG;
1119 UnreachableBlocks &UB;
1125 Instruction *TopInst;
1128 typedef InequalityGraph::Node Node;
1130 /// IdomI - Determines whether one Instruction dominates another.
1131 bool IdomI(Instruction *I1, Instruction *I2) const {
1132 BasicBlock *BB1 = I1->getParent(),
1133 *BB2 = I2->getParent();
1135 if (isa<TerminatorInst>(I1)) return false;
1136 if (isa<TerminatorInst>(I2)) return true;
1137 if (isa<PHINode>(I1) && !isa<PHINode>(I2)) return true;
1138 if (!isa<PHINode>(I1) && isa<PHINode>(I2)) return false;
1140 for (BasicBlock::const_iterator I = BB1->begin(), E = BB1->end();
1142 if (&*I == I1) return true;
1143 if (&*I == I2) return false;
1145 assert(!"Instructions not found in parent BasicBlock?");
1147 return Forest->properlyDominates(BB1, BB2);
1152 /// Returns true if V1 is a better canonical value than V2.
1153 bool compare(Value *V1, Value *V2) const {
1154 if (isa<Constant>(V1))
1155 return !isa<Constant>(V2);
1156 else if (isa<Constant>(V2))
1158 else if (isa<Argument>(V1))
1159 return !isa<Argument>(V2);
1160 else if (isa<Argument>(V2))
1163 Instruction *I1 = dyn_cast<Instruction>(V1);
1164 Instruction *I2 = dyn_cast<Instruction>(V2);
1167 return V1->getNumUses() < V2->getNumUses();
1169 return IdomI(I1, I2);
1172 // below - true if the Instruction is dominated by the current context
1173 // block or instruction
1174 bool below(Instruction *I) {
1176 return IdomI(TopInst, I);
1178 ETNode *Node = Forest->getNodeForBlock(I->getParent());
1179 return Node->DominatedBy(Top);
1183 bool makeEqual(Value *V1, Value *V2) {
1184 DOUT << "makeEqual(" << *V1 << ", " << *V2 << ")\n";
1186 assert(V1->getType() == V2->getType() &&
1187 "Can't make two values with different types equal.");
1189 if (V1 == V2) return true;
1191 if (isa<Constant>(V1) && isa<Constant>(V2))
1194 unsigned n1 = IG.getNode(V1, Top), n2 = IG.getNode(V2, Top);
1197 if (n1 == n2) return true;
1198 if (IG.isRelatedBy(n1, n2, Top, NE)) return false;
1201 if (n1) assert(V1 == IG.node(n1)->getValue() && "Value isn't canonical.");
1202 if (n2) assert(V2 == IG.node(n2)->getValue() && "Value isn't canonical.");
1204 assert(!compare(V2, V1) && "Please order parameters to makeEqual.");
1206 assert(!isa<Constant>(V2) && "Tried to remove a constant.");
1208 SetVector<unsigned> Remove;
1209 if (n2) Remove.insert(n2);
1212 // Suppose we're being told that %x == %y, and %x <= %z and %y >= %z.
1213 // We can't just merge %x and %y because the relationship with %z would
1214 // be EQ and that's invalid. What we're doing is looking for any nodes
1215 // %z such that %x <= %z and %y >= %z, and vice versa.
1217 Node *N1 = IG.node(n1);
1218 Node *N2 = IG.node(n2);
1219 Node::iterator end = N2->end();
1221 // Find the intersection between N1 and N2 which is dominated by
1222 // Top. If we find %x where N1 <= %x <= N2 (or >=) then add %x to
1224 for (Node::iterator I = N1->begin(), E = N1->end(); I != E; ++I) {
1225 if (!(I->LV & EQ_BIT) || !Top->DominatedBy(I->Subtree)) continue;
1227 unsigned ILV_s = I->LV & (SLT_BIT|SGT_BIT);
1228 unsigned ILV_u = I->LV & (ULT_BIT|UGT_BIT);
1229 Node::iterator NI = N2->find(I->To, Top);
1231 LatticeVal NILV = reversePredicate(NI->LV);
1232 unsigned NILV_s = NILV & (SLT_BIT|SGT_BIT);
1233 unsigned NILV_u = NILV & (ULT_BIT|UGT_BIT);
1235 if ((ILV_s != (SLT_BIT|SGT_BIT) && ILV_s == NILV_s) ||
1236 (ILV_u != (ULT_BIT|UGT_BIT) && ILV_u == NILV_u))
1237 Remove.insert(I->To);
1241 // See if one of the nodes about to be removed is actually a better
1242 // canonical choice than n1.
1243 unsigned orig_n1 = n1;
1244 SetVector<unsigned>::iterator DontRemove = Remove.end();
1245 for (SetVector<unsigned>::iterator I = Remove.begin()+1 /* skip n2 */,
1246 E = Remove.end(); I != E; ++I) {
1248 Value *V = IG.node(n)->getValue();
1249 if (compare(V, V1)) {
1255 if (DontRemove != Remove.end()) {
1256 unsigned n = *DontRemove;
1258 Remove.insert(orig_n1);
1262 // We'd like to allow makeEqual on two values to perform a simple
1263 // substitution without every creating nodes in the IG whenever possible.
1265 // The first iteration through this loop operates on V2 before going
1266 // through the Remove list and operating on those too. If all of the
1267 // iterations performed simple replacements then we exit early.
1268 bool mergeIGNode = false;
1270 for (Value *R = V2; i == 0 || i < Remove.size(); ++i) {
1271 if (i) R = IG.node(Remove[i])->getValue(); // skip n2.
1273 // Try to replace the whole instruction. If we can, we're done.
1274 Instruction *I2 = dyn_cast<Instruction>(R);
1275 if (I2 && below(I2)) {
1276 std::vector<Instruction *> ToNotify;
1277 for (Value::use_iterator UI = R->use_begin(), UE = R->use_end();
1279 Use &TheUse = UI.getUse();
1281 if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser()))
1282 ToNotify.push_back(I);
1285 DOUT << "Simply removing " << *I2
1286 << ", replacing with " << *V1 << "\n";
1287 I2->replaceAllUsesWith(V1);
1288 // leave it dead; it'll get erased later.
1292 for (std::vector<Instruction *>::iterator II = ToNotify.begin(),
1293 IE = ToNotify.end(); II != IE; ++II) {
1300 // Otherwise, replace all dominated uses.
1301 for (Value::use_iterator UI = R->use_begin(), UE = R->use_end();
1303 Use &TheUse = UI.getUse();
1305 if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser())) {
1315 // If that killed the instruction, stop here.
1316 if (I2 && isInstructionTriviallyDead(I2)) {
1317 DOUT << "Killed all uses of " << *I2
1318 << ", replacing with " << *V1 << "\n";
1322 // If we make it to here, then we will need to create a node for N1.
1323 // Otherwise, we can skip out early!
1327 if (!isa<Constant>(V1)) {
1328 if (Remove.empty()) {
1329 VR.mergeInto(&V2, 1, V1, Top, this);
1331 std::vector<Value*> RemoveVals;
1332 RemoveVals.reserve(Remove.size());
1334 for (SetVector<unsigned>::iterator I = Remove.begin(),
1335 E = Remove.end(); I != E; ++I) {
1336 Value *V = IG.node(*I)->getValue();
1337 if (!V->use_empty())
1338 RemoveVals.push_back(V);
1340 VR.mergeInto(&RemoveVals[0], RemoveVals.size(), V1, Top, this);
1346 if (!n1) n1 = IG.newNode(V1);
1348 // Migrate relationships from removed nodes to N1.
1349 Node *N1 = IG.node(n1);
1350 for (SetVector<unsigned>::iterator I = Remove.begin(), E = Remove.end();
1353 Node *N = IG.node(n);
1354 for (Node::iterator NI = N->begin(), NE = N->end(); NI != NE; ++NI) {
1355 if (NI->Subtree->DominatedBy(Top)) {
1357 assert((NI->LV & EQ_BIT) && "Node inequal to itself.");
1360 if (Remove.count(NI->To))
1363 IG.node(NI->To)->update(n1, reversePredicate(NI->LV), Top);
1364 N1->update(NI->To, NI->LV, Top);
1369 // Point V2 (and all items in Remove) to N1.
1371 IG.addEquality(n1, V2, Top);
1373 for (SetVector<unsigned>::iterator I = Remove.begin(),
1374 E = Remove.end(); I != E; ++I) {
1375 IG.addEquality(n1, IG.node(*I)->getValue(), Top);
1379 // If !Remove.empty() then V2 = Remove[0]->getValue().
1380 // Even when Remove is empty, we still want to process V2.
1382 for (Value *R = V2; i == 0 || i < Remove.size(); ++i) {
1383 if (i) R = IG.node(Remove[i])->getValue(); // skip n2.
1385 if (Instruction *I2 = dyn_cast<Instruction>(R)) {
1387 Top->DominatedBy(Forest->getNodeForBlock(I2->getParent())))
1390 for (Value::use_iterator UI = V2->use_begin(), UE = V2->use_end();
1392 Use &TheUse = UI.getUse();
1394 if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser())) {
1396 Top->DominatedBy(Forest->getNodeForBlock(I->getParent())))
1403 // re-opsToDef all dominated users of V1.
1404 if (Instruction *I = dyn_cast<Instruction>(V1)) {
1405 for (Value::use_iterator UI = I->use_begin(), UE = I->use_end();
1407 Use &TheUse = UI.getUse();
1409 Value *V = TheUse.getUser();
1410 if (!V->use_empty()) {
1411 if (Instruction *Inst = dyn_cast<Instruction>(V)) {
1413 Top->DominatedBy(Forest->getNodeForBlock(Inst->getParent())))
1423 /// cmpInstToLattice - converts an CmpInst::Predicate to lattice value
1424 /// Requires that the lattice value be valid; does not accept ICMP_EQ.
1425 static LatticeVal cmpInstToLattice(ICmpInst::Predicate Pred) {
1427 case ICmpInst::ICMP_EQ:
1428 assert(!"No matching lattice value.");
1429 return static_cast<LatticeVal>(EQ_BIT);
1431 assert(!"Invalid 'icmp' predicate.");
1432 case ICmpInst::ICMP_NE:
1434 case ICmpInst::ICMP_UGT:
1436 case ICmpInst::ICMP_UGE:
1438 case ICmpInst::ICMP_ULT:
1440 case ICmpInst::ICMP_ULE:
1442 case ICmpInst::ICMP_SGT:
1444 case ICmpInst::ICMP_SGE:
1446 case ICmpInst::ICMP_SLT:
1448 case ICmpInst::ICMP_SLE:
1454 VRPSolver(InequalityGraph &IG, UnreachableBlocks &UB, ValueRanges &VR,
1455 ETForest *Forest, bool &modified, BasicBlock *TopBB)
1460 Top(Forest->getNodeForBlock(TopBB)),
1463 modified(modified) {}
1465 VRPSolver(InequalityGraph &IG, UnreachableBlocks &UB, ValueRanges &VR,
1466 ETForest *Forest, bool &modified, Instruction *TopInst)
1474 TopBB = TopInst->getParent();
1475 Top = Forest->getNodeForBlock(TopBB);
1478 bool isRelatedBy(Value *V1, Value *V2, ICmpInst::Predicate Pred) const {
1479 if (Constant *C1 = dyn_cast<Constant>(V1))
1480 if (Constant *C2 = dyn_cast<Constant>(V2))
1481 return ConstantExpr::getCompare(Pred, C1, C2) ==
1482 ConstantInt::getTrue();
1484 if (unsigned n1 = IG.getNode(V1, Top))
1485 if (unsigned n2 = IG.getNode(V2, Top)) {
1486 if (n1 == n2) return Pred == ICmpInst::ICMP_EQ ||
1487 Pred == ICmpInst::ICMP_ULE ||
1488 Pred == ICmpInst::ICMP_UGE ||
1489 Pred == ICmpInst::ICMP_SLE ||
1490 Pred == ICmpInst::ICMP_SGE;
1491 if (Pred == ICmpInst::ICMP_EQ) return false;
1492 if (IG.isRelatedBy(n1, n2, Top, cmpInstToLattice(Pred))) return true;
1495 if (Pred == ICmpInst::ICMP_EQ) return V1 == V2;
1496 return VR.isRelatedBy(V1, V2, Top, cmpInstToLattice(Pred));
1499 /// add - adds a new property to the work queue
1500 void add(Value *V1, Value *V2, ICmpInst::Predicate Pred,
1501 Instruction *I = NULL) {
1502 DOUT << "adding " << *V1 << " " << Pred << " " << *V2;
1503 if (I) DOUT << " context: " << *I;
1504 else DOUT << " default context";
1507 assert(V1->getType() == V2->getType() &&
1508 "Can't relate two values with different types.");
1510 WorkList.push_back(Operation());
1511 Operation &O = WorkList.back();
1512 O.LHS = V1, O.RHS = V2, O.Op = Pred, O.ContextInst = I;
1513 O.ContextBB = I ? I->getParent() : TopBB;
1516 /// defToOps - Given an instruction definition that we've learned something
1517 /// new about, find any new relationships between its operands.
1518 void defToOps(Instruction *I) {
1519 Instruction *NewContext = below(I) ? I : TopInst;
1520 Value *Canonical = IG.canonicalize(I, Top);
1522 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
1523 const Type *Ty = BO->getType();
1524 assert(!Ty->isFPOrFPVector() && "Float in work queue!");
1526 Value *Op0 = IG.canonicalize(BO->getOperand(0), Top);
1527 Value *Op1 = IG.canonicalize(BO->getOperand(1), Top);
1529 // TODO: "and i32 -1, %x" EQ %y then %x EQ %y.
1531 switch (BO->getOpcode()) {
1532 case Instruction::And: {
1533 // "and i32 %a, %b" EQ -1 then %a EQ -1 and %b EQ -1
1534 ConstantInt *CI = ConstantInt::getAllOnesValue(Ty);
1535 if (Canonical == CI) {
1536 add(CI, Op0, ICmpInst::ICMP_EQ, NewContext);
1537 add(CI, Op1, ICmpInst::ICMP_EQ, NewContext);
1540 case Instruction::Or: {
1541 // "or i32 %a, %b" EQ 0 then %a EQ 0 and %b EQ 0
1542 Constant *Zero = Constant::getNullValue(Ty);
1543 if (Canonical == Zero) {
1544 add(Zero, Op0, ICmpInst::ICMP_EQ, NewContext);
1545 add(Zero, Op1, ICmpInst::ICMP_EQ, NewContext);
1548 case Instruction::Xor: {
1549 // "xor i32 %c, %a" EQ %b then %a EQ %c ^ %b
1550 // "xor i32 %c, %a" EQ %c then %a EQ 0
1551 // "xor i32 %c, %a" NE %c then %a NE 0
1552 // Repeat the above, with order of operands reversed.
1555 if (!isa<Constant>(LHS)) std::swap(LHS, RHS);
1557 if (ConstantInt *CI = dyn_cast<ConstantInt>(Canonical)) {
1558 if (ConstantInt *Arg = dyn_cast<ConstantInt>(LHS)) {
1559 add(RHS, ConstantInt::get(CI->getValue() ^ Arg->getValue()),
1560 ICmpInst::ICMP_EQ, NewContext);
1563 if (Canonical == LHS) {
1564 if (isa<ConstantInt>(Canonical))
1565 add(RHS, Constant::getNullValue(Ty), ICmpInst::ICMP_EQ,
1567 } else if (isRelatedBy(LHS, Canonical, ICmpInst::ICMP_NE)) {
1568 add(RHS, Constant::getNullValue(Ty), ICmpInst::ICMP_NE,
1575 } else if (ICmpInst *IC = dyn_cast<ICmpInst>(I)) {
1576 // "icmp ult i32 %a, %y" EQ true then %a u< y
1579 if (Canonical == ConstantInt::getTrue()) {
1580 add(IC->getOperand(0), IC->getOperand(1), IC->getPredicate(),
1582 } else if (Canonical == ConstantInt::getFalse()) {
1583 add(IC->getOperand(0), IC->getOperand(1),
1584 ICmpInst::getInversePredicate(IC->getPredicate()), NewContext);
1586 } else if (SelectInst *SI = dyn_cast<SelectInst>(I)) {
1587 if (I->getType()->isFPOrFPVector()) return;
1589 // Given: "%a = select i1 %x, i32 %b, i32 %c"
1590 // %a EQ %b and %b NE %c then %x EQ true
1591 // %a EQ %c and %b NE %c then %x EQ false
1593 Value *True = SI->getTrueValue();
1594 Value *False = SI->getFalseValue();
1595 if (isRelatedBy(True, False, ICmpInst::ICMP_NE)) {
1596 if (Canonical == IG.canonicalize(True, Top) ||
1597 isRelatedBy(Canonical, False, ICmpInst::ICMP_NE))
1598 add(SI->getCondition(), ConstantInt::getTrue(),
1599 ICmpInst::ICMP_EQ, NewContext);
1600 else if (Canonical == IG.canonicalize(False, Top) ||
1601 isRelatedBy(Canonical, True, ICmpInst::ICMP_NE))
1602 add(SI->getCondition(), ConstantInt::getFalse(),
1603 ICmpInst::ICMP_EQ, NewContext);
1605 } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
1606 for (GetElementPtrInst::op_iterator OI = GEPI->idx_begin(),
1607 OE = GEPI->idx_end(); OI != OE; ++OI) {
1608 ConstantInt *Op = dyn_cast<ConstantInt>(IG.canonicalize(*OI, Top));
1609 if (!Op || !Op->isZero()) return;
1611 // TODO: The GEPI indices are all zero. Copy from definition to operand,
1612 // jumping the type plane as needed.
1613 if (isRelatedBy(GEPI, Constant::getNullValue(GEPI->getType()),
1614 ICmpInst::ICMP_NE)) {
1615 Value *Ptr = GEPI->getPointerOperand();
1616 add(Ptr, Constant::getNullValue(Ptr->getType()), ICmpInst::ICMP_NE,
1619 } else if (CastInst *CI = dyn_cast<CastInst>(I)) {
1620 const Type *SrcTy = CI->getSrcTy();
1622 Value *TheCI = IG.canonicalize(CI, Top);
1623 uint32_t W = VR.typeToWidth(SrcTy);
1625 ConstantRange CR = VR.rangeFromValue(TheCI, Top, W);
1627 if (CR.isFullSet()) return;
1629 switch (CI->getOpcode()) {
1631 case Instruction::ZExt:
1632 case Instruction::SExt:
1633 VR.applyRange(IG.canonicalize(CI->getOperand(0), Top),
1634 CR.truncate(W), Top, this);
1636 case Instruction::BitCast:
1637 VR.applyRange(IG.canonicalize(CI->getOperand(0), Top),
1644 /// opsToDef - A new relationship was discovered involving one of this
1645 /// instruction's operands. Find any new relationship involving the
1646 /// definition, or another operand.
1647 void opsToDef(Instruction *I) {
1648 Instruction *NewContext = below(I) ? I : TopInst;
1650 if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
1651 Value *Op0 = IG.canonicalize(BO->getOperand(0), Top);
1652 Value *Op1 = IG.canonicalize(BO->getOperand(1), Top);
1654 if (ConstantInt *CI0 = dyn_cast<ConstantInt>(Op0))
1655 if (ConstantInt *CI1 = dyn_cast<ConstantInt>(Op1)) {
1656 add(BO, ConstantExpr::get(BO->getOpcode(), CI0, CI1),
1657 ICmpInst::ICMP_EQ, NewContext);
1661 // "%y = and i1 true, %x" then %x EQ %y
1662 // "%y = or i1 false, %x" then %x EQ %y
1663 // "%x = add i32 %y, 0" then %x EQ %y
1664 // "%x = mul i32 %y, 0" then %x EQ 0
1666 Instruction::BinaryOps Opcode = BO->getOpcode();
1667 const Type *Ty = BO->getType();
1668 assert(!Ty->isFPOrFPVector() && "Float in work queue!");
1670 Constant *Zero = Constant::getNullValue(Ty);
1671 ConstantInt *AllOnes = ConstantInt::getAllOnesValue(Ty);
1675 case Instruction::LShr:
1676 case Instruction::AShr:
1677 case Instruction::Shl:
1678 case Instruction::Sub:
1680 add(BO, Op0, ICmpInst::ICMP_EQ, NewContext);
1684 case Instruction::Or:
1685 if (Op0 == AllOnes || Op1 == AllOnes) {
1686 add(BO, AllOnes, ICmpInst::ICMP_EQ, NewContext);
1689 case Instruction::Xor:
1690 case Instruction::Add:
1692 add(BO, Op1, ICmpInst::ICMP_EQ, NewContext);
1694 } else if (Op1 == Zero) {
1695 add(BO, Op0, ICmpInst::ICMP_EQ, NewContext);
1699 case Instruction::And:
1700 if (Op0 == AllOnes) {
1701 add(BO, Op1, ICmpInst::ICMP_EQ, NewContext);
1703 } else if (Op1 == AllOnes) {
1704 add(BO, Op0, ICmpInst::ICMP_EQ, NewContext);
1708 case Instruction::Mul:
1709 if (Op0 == Zero || Op1 == Zero) {
1710 add(BO, Zero, ICmpInst::ICMP_EQ, NewContext);
1716 // "%x = add i32 %y, %z" and %x EQ %y then %z EQ 0
1717 // "%x = add i32 %y, %z" and %x EQ %z then %y EQ 0
1718 // "%x = shl i32 %y, %z" and %x EQ %y and %y NE 0 then %z EQ 0
1719 // "%x = udiv i32 %y, %z" and %x EQ %y then %z EQ 1
1721 Value *Known = Op0, *Unknown = Op1,
1722 *TheBO = IG.canonicalize(BO, Top);
1723 if (Known != TheBO) std::swap(Known, Unknown);
1724 if (Known == TheBO) {
1727 case Instruction::LShr:
1728 case Instruction::AShr:
1729 case Instruction::Shl:
1730 if (!isRelatedBy(Known, Zero, ICmpInst::ICMP_NE)) break;
1731 // otherwise, fall-through.
1732 case Instruction::Sub:
1733 if (Unknown == Op1) break;
1734 // otherwise, fall-through.
1735 case Instruction::Xor:
1736 case Instruction::Add:
1737 add(Unknown, Zero, ICmpInst::ICMP_EQ, NewContext);
1739 case Instruction::UDiv:
1740 case Instruction::SDiv:
1741 if (Unknown == Op1) break;
1742 if (isRelatedBy(Known, Zero, ICmpInst::ICMP_NE)) {
1743 Constant *One = ConstantInt::get(Ty, 1);
1744 add(Unknown, One, ICmpInst::ICMP_EQ, NewContext);
1750 // TODO: "%a = add i32 %b, 1" and %b > %z then %a >= %z.
1752 } else if (ICmpInst *IC = dyn_cast<ICmpInst>(I)) {
1753 // "%a = icmp ult i32 %b, %c" and %b u< %c then %a EQ true
1754 // "%a = icmp ult i32 %b, %c" and %b u>= %c then %a EQ false
1757 Value *Op0 = IG.canonicalize(IC->getOperand(0), Top);
1758 Value *Op1 = IG.canonicalize(IC->getOperand(1), Top);
1760 ICmpInst::Predicate Pred = IC->getPredicate();
1761 if (isRelatedBy(Op0, Op1, Pred)) {
1762 add(IC, ConstantInt::getTrue(), ICmpInst::ICMP_EQ, NewContext);
1763 } else if (isRelatedBy(Op0, Op1, ICmpInst::getInversePredicate(Pred))) {
1764 add(IC, ConstantInt::getFalse(), ICmpInst::ICMP_EQ, NewContext);
1767 } else if (SelectInst *SI = dyn_cast<SelectInst>(I)) {
1768 if (I->getType()->isFPOrFPVector()) return;
1770 // Given: "%a = select i1 %x, i32 %b, i32 %c"
1771 // %x EQ true then %a EQ %b
1772 // %x EQ false then %a EQ %c
1773 // %b EQ %c then %a EQ %b
1775 Value *Canonical = IG.canonicalize(SI->getCondition(), Top);
1776 if (Canonical == ConstantInt::getTrue()) {
1777 add(SI, SI->getTrueValue(), ICmpInst::ICMP_EQ, NewContext);
1778 } else if (Canonical == ConstantInt::getFalse()) {
1779 add(SI, SI->getFalseValue(), ICmpInst::ICMP_EQ, NewContext);
1780 } else if (IG.canonicalize(SI->getTrueValue(), Top) ==
1781 IG.canonicalize(SI->getFalseValue(), Top)) {
1782 add(SI, SI->getTrueValue(), ICmpInst::ICMP_EQ, NewContext);
1784 } else if (CastInst *CI = dyn_cast<CastInst>(I)) {
1785 const Type *DestTy = CI->getDestTy();
1786 if (DestTy->isFPOrFPVector()) return;
1788 Value *Op = IG.canonicalize(CI->getOperand(0), Top);
1789 Instruction::CastOps Opcode = CI->getOpcode();
1791 if (Constant *C = dyn_cast<Constant>(Op)) {
1792 add(CI, ConstantExpr::getCast(Opcode, C, DestTy),
1793 ICmpInst::ICMP_EQ, NewContext);
1796 uint32_t W = VR.typeToWidth(DestTy);
1797 Value *TheCI = IG.canonicalize(CI, Top);
1798 ConstantRange CR = VR.rangeFromValue(Op, Top, W);
1800 if (!CR.isFullSet()) {
1803 case Instruction::ZExt:
1804 VR.applyRange(TheCI, CR.zeroExtend(W), Top, this);
1806 case Instruction::SExt:
1807 VR.applyRange(TheCI, CR.signExtend(W), Top, this);
1809 case Instruction::Trunc: {
1810 ConstantRange Result = CR.truncate(W);
1811 if (!Result.isFullSet())
1812 VR.applyRange(TheCI, Result, Top, this);
1814 case Instruction::BitCast:
1815 VR.applyRange(TheCI, CR, Top, this);
1817 // TODO: other casts?
1820 } else if (GetElementPtrInst *GEPI = dyn_cast<GetElementPtrInst>(I)) {
1821 for (GetElementPtrInst::op_iterator OI = GEPI->idx_begin(),
1822 OE = GEPI->idx_end(); OI != OE; ++OI) {
1823 ConstantInt *Op = dyn_cast<ConstantInt>(IG.canonicalize(*OI, Top));
1824 if (!Op || !Op->isZero()) return;
1826 // TODO: The GEPI indices are all zero. Copy from operand to definition,
1827 // jumping the type plane as needed.
1828 Value *Ptr = GEPI->getPointerOperand();
1829 if (isRelatedBy(Ptr, Constant::getNullValue(Ptr->getType()),
1830 ICmpInst::ICMP_NE)) {
1831 add(GEPI, Constant::getNullValue(GEPI->getType()), ICmpInst::ICMP_NE,
1837 /// solve - process the work queue
1839 //DOUT << "WorkList entry, size: " << WorkList.size() << "\n";
1840 while (!WorkList.empty()) {
1841 //DOUT << "WorkList size: " << WorkList.size() << "\n";
1843 Operation &O = WorkList.front();
1844 TopInst = O.ContextInst;
1845 TopBB = O.ContextBB;
1846 Top = Forest->getNodeForBlock(TopBB);
1848 O.LHS = IG.canonicalize(O.LHS, Top);
1849 O.RHS = IG.canonicalize(O.RHS, Top);
1851 assert(O.LHS == IG.canonicalize(O.LHS, Top) && "Canonicalize isn't.");
1852 assert(O.RHS == IG.canonicalize(O.RHS, Top) && "Canonicalize isn't.");
1854 DOUT << "solving " << *O.LHS << " " << O.Op << " " << *O.RHS;
1855 if (O.ContextInst) DOUT << " context inst: " << *O.ContextInst;
1856 else DOUT << " context block: " << O.ContextBB->getName();
1861 // If they're both Constant, skip it. Check for contradiction and mark
1862 // the BB as unreachable if so.
1863 if (Constant *CI_L = dyn_cast<Constant>(O.LHS)) {
1864 if (Constant *CI_R = dyn_cast<Constant>(O.RHS)) {
1865 if (ConstantExpr::getCompare(O.Op, CI_L, CI_R) ==
1866 ConstantInt::getFalse())
1869 WorkList.pop_front();
1874 if (compare(O.LHS, O.RHS)) {
1875 std::swap(O.LHS, O.RHS);
1876 O.Op = ICmpInst::getSwappedPredicate(O.Op);
1879 if (O.Op == ICmpInst::ICMP_EQ) {
1880 if (!makeEqual(O.RHS, O.LHS))
1883 LatticeVal LV = cmpInstToLattice(O.Op);
1885 if ((LV & EQ_BIT) &&
1886 isRelatedBy(O.LHS, O.RHS, ICmpInst::getSwappedPredicate(O.Op))) {
1887 if (!makeEqual(O.RHS, O.LHS))
1890 if (isRelatedBy(O.LHS, O.RHS, ICmpInst::getInversePredicate(O.Op))){
1892 WorkList.pop_front();
1896 unsigned n1 = IG.getNode(O.LHS, Top);
1897 unsigned n2 = IG.getNode(O.RHS, Top);
1899 if (n1 && n1 == n2) {
1900 if (O.Op != ICmpInst::ICMP_UGE && O.Op != ICmpInst::ICMP_ULE &&
1901 O.Op != ICmpInst::ICMP_SGE && O.Op != ICmpInst::ICMP_SLE)
1904 WorkList.pop_front();
1908 if (VR.isRelatedBy(O.LHS, O.RHS, Top, LV) ||
1909 (n1 && n2 && IG.isRelatedBy(n1, n2, Top, LV))) {
1910 WorkList.pop_front();
1914 VR.addInequality(O.LHS, O.RHS, Top, LV, this);
1915 if ((!isa<ConstantInt>(O.RHS) && !isa<ConstantInt>(O.LHS)) ||
1917 if (!n1) n1 = IG.newNode(O.LHS);
1918 if (!n2) n2 = IG.newNode(O.RHS);
1919 IG.addInequality(n1, n2, Top, LV);
1922 if (Instruction *I1 = dyn_cast<Instruction>(O.LHS)) {
1924 Top->DominatedBy(Forest->getNodeForBlock(I1->getParent())))
1927 if (isa<Instruction>(O.LHS) || isa<Argument>(O.LHS)) {
1928 for (Value::use_iterator UI = O.LHS->use_begin(),
1929 UE = O.LHS->use_end(); UI != UE;) {
1930 Use &TheUse = UI.getUse();
1932 if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser())) {
1934 Top->DominatedBy(Forest->getNodeForBlock(I->getParent())))
1939 if (Instruction *I2 = dyn_cast<Instruction>(O.RHS)) {
1941 Top->DominatedBy(Forest->getNodeForBlock(I2->getParent())))
1944 if (isa<Instruction>(O.RHS) || isa<Argument>(O.RHS)) {
1945 for (Value::use_iterator UI = O.RHS->use_begin(),
1946 UE = O.RHS->use_end(); UI != UE;) {
1947 Use &TheUse = UI.getUse();
1949 if (Instruction *I = dyn_cast<Instruction>(TheUse.getUser())) {
1951 Top->DominatedBy(Forest->getNodeForBlock(I->getParent())))
1959 WorkList.pop_front();
1964 void ValueRanges::addToWorklist(Value *V, Constant *C,
1965 ICmpInst::Predicate Pred, VRPSolver *VRP) {
1966 VRP->add(V, C, Pred, VRP->TopInst);
1969 void ValueRanges::markBlock(VRPSolver *VRP) {
1970 VRP->UB.mark(VRP->TopBB);
1974 bool ValueRanges::isCanonical(Value *V, ETNode *Subtree, VRPSolver *VRP) {
1975 return V == VRP->IG.canonicalize(V, Subtree);
1979 /// PredicateSimplifier - This class is a simplifier that replaces
1980 /// one equivalent variable with another. It also tracks what
1981 /// can't be equal and will solve setcc instructions when possible.
1982 /// @brief Root of the predicate simplifier optimization.
1983 class VISIBILITY_HIDDEN PredicateSimplifier : public FunctionPass {
1987 InequalityGraph *IG;
1988 UnreachableBlocks UB;
1991 std::vector<DominatorTree::Node *> WorkList;
1994 bool runOnFunction(Function &F);
1996 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
1997 AU.addRequiredID(BreakCriticalEdgesID);
1998 AU.addRequired<DominatorTree>();
1999 AU.addRequired<ETForest>();
2000 AU.addRequired<TargetData>();
2001 AU.addPreserved<TargetData>();
2005 /// Forwards - Adds new properties into PropertySet and uses them to
2006 /// simplify instructions. Because new properties sometimes apply to
2007 /// a transition from one BasicBlock to another, this will use the
2008 /// PredicateSimplifier::proceedToSuccessor(s) interface to enter the
2009 /// basic block with the new PropertySet.
2010 /// @brief Performs abstract execution of the program.
2011 class VISIBILITY_HIDDEN Forwards : public InstVisitor<Forwards> {
2012 friend class InstVisitor<Forwards>;
2013 PredicateSimplifier *PS;
2014 DominatorTree::Node *DTNode;
2017 InequalityGraph &IG;
2018 UnreachableBlocks &UB;
2021 Forwards(PredicateSimplifier *PS, DominatorTree::Node *DTNode)
2022 : PS(PS), DTNode(DTNode), IG(*PS->IG), UB(PS->UB), VR(*PS->VR) {}
2024 void visitTerminatorInst(TerminatorInst &TI);
2025 void visitBranchInst(BranchInst &BI);
2026 void visitSwitchInst(SwitchInst &SI);
2028 void visitAllocaInst(AllocaInst &AI);
2029 void visitLoadInst(LoadInst &LI);
2030 void visitStoreInst(StoreInst &SI);
2032 void visitSExtInst(SExtInst &SI);
2033 void visitZExtInst(ZExtInst &ZI);
2035 void visitBinaryOperator(BinaryOperator &BO);
2036 void visitICmpInst(ICmpInst &IC);
2039 // Used by terminator instructions to proceed from the current basic
2040 // block to the next. Verifies that "current" dominates "next",
2041 // then calls visitBasicBlock.
2042 void proceedToSuccessors(DominatorTree::Node *Current) {
2043 for (DominatorTree::Node::iterator I = Current->begin(),
2044 E = Current->end(); I != E; ++I) {
2045 WorkList.push_back(*I);
2049 void proceedToSuccessor(DominatorTree::Node *Next) {
2050 WorkList.push_back(Next);
2053 // Visits each instruction in the basic block.
2054 void visitBasicBlock(DominatorTree::Node *Node) {
2055 BasicBlock *BB = Node->getBlock();
2056 ETNode *ET = Forest->getNodeForBlock(BB);
2057 DOUT << "Entering Basic Block: " << BB->getName()
2058 << " (" << ET->getDFSNumIn() << ")\n";
2059 for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
2060 visitInstruction(I++, Node, ET);
2064 // Tries to simplify each Instruction and add new properties to
2066 void visitInstruction(Instruction *I, DominatorTree::Node *DT, ETNode *ET) {
2067 DOUT << "Considering instruction " << *I << "\n";
2070 // Sometimes instructions are killed in earlier analysis.
2071 if (isInstructionTriviallyDead(I)) {
2075 I->eraseFromParent();
2080 // Try to replace the whole instruction.
2081 Value *V = IG->canonicalize(I, ET);
2082 assert(V == I && "Late instruction canonicalization.");
2086 DOUT << "Removing " << *I << ", replacing with " << *V << "\n";
2088 I->replaceAllUsesWith(V);
2089 I->eraseFromParent();
2093 // Try to substitute operands.
2094 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
2095 Value *Oper = I->getOperand(i);
2096 Value *V = IG->canonicalize(Oper, ET);
2097 assert(V == Oper && "Late operand canonicalization.");
2101 DOUT << "Resolving " << *I;
2102 I->setOperand(i, V);
2103 DOUT << " into " << *I;
2108 std::string name = I->getParent()->getName();
2109 DOUT << "push (%" << name << ")\n";
2110 Forwards visit(this, DT);
2112 DOUT << "pop (%" << name << ")\n";
2116 bool PredicateSimplifier::runOnFunction(Function &F) {
2117 DT = &getAnalysis<DominatorTree>();
2118 Forest = &getAnalysis<ETForest>();
2120 TargetData *TD = &getAnalysis<TargetData>();
2122 Forest->updateDFSNumbers(); // XXX: should only act when numbers are out of date
2124 DOUT << "Entering Function: " << F.getName() << "\n";
2127 BasicBlock *RootBlock = &F.getEntryBlock();
2128 IG = new InequalityGraph(Forest->getNodeForBlock(RootBlock));
2129 VR = new ValueRanges(TD);
2130 WorkList.push_back(DT->getRootNode());
2133 DominatorTree::Node *DTNode = WorkList.back();
2134 WorkList.pop_back();
2135 if (!UB.isDead(DTNode->getBlock())) visitBasicBlock(DTNode);
2136 } while (!WorkList.empty());
2141 modified |= UB.kill();
2146 void PredicateSimplifier::Forwards::visitTerminatorInst(TerminatorInst &TI) {
2147 PS->proceedToSuccessors(DTNode);
2150 void PredicateSimplifier::Forwards::visitBranchInst(BranchInst &BI) {
2151 if (BI.isUnconditional()) {
2152 PS->proceedToSuccessors(DTNode);
2156 Value *Condition = BI.getCondition();
2157 BasicBlock *TrueDest = BI.getSuccessor(0);
2158 BasicBlock *FalseDest = BI.getSuccessor(1);
2160 if (isa<Constant>(Condition) || TrueDest == FalseDest) {
2161 PS->proceedToSuccessors(DTNode);
2165 for (DominatorTree::Node::iterator I = DTNode->begin(), E = DTNode->end();
2167 BasicBlock *Dest = (*I)->getBlock();
2168 DOUT << "Branch thinking about %" << Dest->getName()
2169 << "(" << PS->Forest->getNodeForBlock(Dest)->getDFSNumIn() << ")\n";
2171 if (Dest == TrueDest) {
2172 DOUT << "(" << DTNode->getBlock()->getName() << ") true set:\n";
2173 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, Dest);
2174 VRP.add(ConstantInt::getTrue(), Condition, ICmpInst::ICMP_EQ);
2177 } else if (Dest == FalseDest) {
2178 DOUT << "(" << DTNode->getBlock()->getName() << ") false set:\n";
2179 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, Dest);
2180 VRP.add(ConstantInt::getFalse(), Condition, ICmpInst::ICMP_EQ);
2185 PS->proceedToSuccessor(*I);
2189 void PredicateSimplifier::Forwards::visitSwitchInst(SwitchInst &SI) {
2190 Value *Condition = SI.getCondition();
2192 // Set the EQProperty in each of the cases BBs, and the NEProperties
2193 // in the default BB.
2195 for (DominatorTree::Node::iterator I = DTNode->begin(), E = DTNode->end();
2197 BasicBlock *BB = (*I)->getBlock();
2198 DOUT << "Switch thinking about BB %" << BB->getName()
2199 << "(" << PS->Forest->getNodeForBlock(BB)->getDFSNumIn() << ")\n";
2201 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, BB);
2202 if (BB == SI.getDefaultDest()) {
2203 for (unsigned i = 1, e = SI.getNumCases(); i < e; ++i)
2204 if (SI.getSuccessor(i) != BB)
2205 VRP.add(Condition, SI.getCaseValue(i), ICmpInst::ICMP_NE);
2207 } else if (ConstantInt *CI = SI.findCaseDest(BB)) {
2208 VRP.add(Condition, CI, ICmpInst::ICMP_EQ);
2211 PS->proceedToSuccessor(*I);
2215 void PredicateSimplifier::Forwards::visitAllocaInst(AllocaInst &AI) {
2216 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, &AI);
2217 VRP.add(Constant::getNullValue(AI.getType()), &AI, ICmpInst::ICMP_NE);
2221 void PredicateSimplifier::Forwards::visitLoadInst(LoadInst &LI) {
2222 Value *Ptr = LI.getPointerOperand();
2223 // avoid "load uint* null" -> null NE null.
2224 if (isa<Constant>(Ptr)) return;
2226 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, &LI);
2227 VRP.add(Constant::getNullValue(Ptr->getType()), Ptr, ICmpInst::ICMP_NE);
2231 void PredicateSimplifier::Forwards::visitStoreInst(StoreInst &SI) {
2232 Value *Ptr = SI.getPointerOperand();
2233 if (isa<Constant>(Ptr)) return;
2235 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, &SI);
2236 VRP.add(Constant::getNullValue(Ptr->getType()), Ptr, ICmpInst::ICMP_NE);
2240 void PredicateSimplifier::Forwards::visitSExtInst(SExtInst &SI) {
2241 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, &SI);
2242 uint32_t SrcBitWidth = cast<IntegerType>(SI.getSrcTy())->getBitWidth();
2243 uint32_t DstBitWidth = cast<IntegerType>(SI.getDestTy())->getBitWidth();
2244 APInt Min(APInt::getSignedMinValue(SrcBitWidth));
2245 APInt Max(APInt::getSignedMaxValue(SrcBitWidth));
2246 Min.sext(DstBitWidth);
2247 Max.sext(DstBitWidth);
2248 VRP.add(ConstantInt::get(Min), &SI, ICmpInst::ICMP_SLE);
2249 VRP.add(ConstantInt::get(Max), &SI, ICmpInst::ICMP_SGE);
2253 void PredicateSimplifier::Forwards::visitZExtInst(ZExtInst &ZI) {
2254 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, &ZI);
2255 uint32_t SrcBitWidth = cast<IntegerType>(ZI.getSrcTy())->getBitWidth();
2256 uint32_t DstBitWidth = cast<IntegerType>(ZI.getDestTy())->getBitWidth();
2257 APInt Max(APInt::getMaxValue(SrcBitWidth));
2258 Max.zext(DstBitWidth);
2259 VRP.add(ConstantInt::get(Max), &ZI, ICmpInst::ICMP_UGE);
2263 void PredicateSimplifier::Forwards::visitBinaryOperator(BinaryOperator &BO) {
2264 Instruction::BinaryOps ops = BO.getOpcode();
2268 case Instruction::URem:
2269 case Instruction::SRem:
2270 case Instruction::UDiv:
2271 case Instruction::SDiv: {
2272 Value *Divisor = BO.getOperand(1);
2273 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, &BO);
2274 VRP.add(Constant::getNullValue(Divisor->getType()), Divisor,
2283 case Instruction::Shl: {
2284 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, &BO);
2285 VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_UGE);
2288 case Instruction::AShr: {
2289 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, &BO);
2290 VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_SLE);
2293 case Instruction::LShr:
2294 case Instruction::UDiv: {
2295 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, &BO);
2296 VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_ULE);
2299 case Instruction::URem: {
2300 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, &BO);
2301 VRP.add(&BO, BO.getOperand(1), ICmpInst::ICMP_ULE);
2304 case Instruction::And: {
2305 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, &BO);
2306 VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_ULE);
2307 VRP.add(&BO, BO.getOperand(1), ICmpInst::ICMP_ULE);
2310 case Instruction::Or: {
2311 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, &BO);
2312 VRP.add(&BO, BO.getOperand(0), ICmpInst::ICMP_UGE);
2313 VRP.add(&BO, BO.getOperand(1), ICmpInst::ICMP_UGE);
2319 void PredicateSimplifier::Forwards::visitICmpInst(ICmpInst &IC) {
2320 // If possible, squeeze the ICmp predicate into something simpler.
2321 // Eg., if x = [0, 4) and we're being asked icmp uge %x, 3 then change
2322 // the predicate to eq.
2324 // XXX: once we do full PHI handling, modifying the instruction in the
2325 // Forwards visitor will cause missed optimizations.
2327 ICmpInst::Predicate Pred = IC.getPredicate();
2331 case ICmpInst::ICMP_ULE: Pred = ICmpInst::ICMP_ULT; break;
2332 case ICmpInst::ICMP_UGE: Pred = ICmpInst::ICMP_UGT; break;
2333 case ICmpInst::ICMP_SLE: Pred = ICmpInst::ICMP_SLT; break;
2334 case ICmpInst::ICMP_SGE: Pred = ICmpInst::ICMP_SGT; break;
2336 if (Pred != IC.getPredicate()) {
2337 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, &IC);
2338 if (VRP.isRelatedBy(IC.getOperand(1), IC.getOperand(0),
2339 ICmpInst::ICMP_NE)) {
2341 PS->modified = true;
2342 IC.setPredicate(Pred);
2346 Pred = IC.getPredicate();
2348 if (ConstantInt *Op1 = dyn_cast<ConstantInt>(IC.getOperand(1))) {
2349 ConstantInt *NextVal = 0;
2352 case ICmpInst::ICMP_SLT:
2353 case ICmpInst::ICMP_ULT:
2354 if (Op1->getValue() != 0)
2355 NextVal = cast<ConstantInt>(ConstantExpr::getSub(
2356 Op1, ConstantInt::get(Op1->getType(), 1)));
2358 case ICmpInst::ICMP_SGT:
2359 case ICmpInst::ICMP_UGT:
2360 if (!Op1->getValue().isAllOnesValue())
2361 NextVal = cast<ConstantInt>(ConstantExpr::getAdd(
2362 Op1, ConstantInt::get(Op1->getType(), 1)));
2367 VRPSolver VRP(IG, UB, VR, PS->Forest, PS->modified, &IC);
2368 if (VRP.isRelatedBy(IC.getOperand(0), NextVal,
2369 ICmpInst::getInversePredicate(Pred))) {
2370 ICmpInst *NewIC = new ICmpInst(ICmpInst::ICMP_EQ, IC.getOperand(0),
2372 NewIC->takeName(&IC);
2373 IC.replaceAllUsesWith(NewIC);
2374 IG.remove(&IC); // XXX: prove this isn't necessary
2375 IC.eraseFromParent();
2377 PS->modified = true;
2383 RegisterPass<PredicateSimplifier> X("predsimplify",
2384 "Predicate Simplifier");
2387 FunctionPass *llvm::createPredicateSimplifierPass() {
2388 return new PredicateSimplifier();