[llvm-commits] CVS: llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp
Nick Lewycky
nicholas at mxc.ca
Sat Sep 9 19:27:22 PDT 2006
Changes in directory llvm/lib/Transforms/Scalar:
PredicateSimplifier.cpp updated: 1.5 -> 1.6
---
Log message:
Replace EquivalenceClasses with a custom-built data structure. Many common
operations (like findProperties) should be faster, at the expense of
unionSets being slower in cases that are rare in practise.
Don't erase a dead Instruction. This fixes a memory corruption issue.
---
Diffs of the changes: (+261 -135)
PredicateSimplifier.cpp | 396 +++++++++++++++++++++++++++++++-----------------
1 files changed, 261 insertions(+), 135 deletions(-)
Index: llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp
diff -u llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp:1.5 llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp:1.6
--- llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp:1.5 Sat Sep 2 14:40:37 2006
+++ llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp Sat Sep 9 21:27:07 2006
@@ -33,7 +33,6 @@
#include "llvm/Constants.h"
#include "llvm/Instructions.h"
#include "llvm/Pass.h"
-#include "llvm/ADT/EquivalenceClasses.h"
#include "llvm/ADT/Statistic.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/Analysis/Dominators.h"
@@ -42,6 +41,8 @@
#include <iostream>
using namespace llvm;
+typedef DominatorTree::Node DTNodeType;
+
namespace {
Statistic<>
NumVarsReplaced("predsimplify", "Number of argument substitutions");
@@ -52,40 +53,167 @@
Statistic<>
NumBranches("predsimplify", "Number of branches made unconditional");
- /// Used for choosing the canonical Value in a synonym set.
- /// Leaves the better one in V1. Returns whether a swap took place.
- static void order(Value *&V1, Value *&V2) {
- if (isa<Constant>(V2)) {
- if (!isa<Constant>(V1)) {
- std::swap(V1, V2);
- return;
- }
- } else if (isa<Argument>(V2)) {
- if (!isa<Constant>(V1) && !isa<Argument>(V1)) {
- std::swap(V1, V2);
- return;
- }
- }
- if (User *U1 = dyn_cast<User>(V1)) {
- for (User::const_op_iterator I = U1->op_begin(), E = U1->op_end();
- I != E; ++I) {
- if (*I == V2) {
- std::swap(V1, V2);
- return;
+ /// Returns true if V1 is a better choice than V2. Note that it is
+ /// not a total ordering.
+ struct compare {
+ bool operator()(Value *V1, Value *V2) const {
+ if (isa<Constant>(V2)) {
+ if (!isa<Constant>(V1)) {
+ return true;
+ }
+ } else if (isa<Argument>(V2)) {
+ if (!isa<Constant>(V1) && !isa<Argument>(V1)) {
+ return true;
+ }
+ }
+ if (User *U1 = dyn_cast<User>(V1)) {
+ for (User::const_op_iterator I = U1->op_begin(), E = U1->op_end();
+ I != E; ++I) {
+ if (*I == V2) {
+ return true;
+ }
}
}
+ return false;
}
- return;
+ };
+
+ /// Used for choosing the canonical Value in a synonym set.
+ /// Leaves the better one in V1.
+ static void order(Value *&V1, Value *&V2) {
+ static compare c;
+ if (c(V1, V2))
+ std::swap(V1, V2);
}
+ /// Similar to EquivalenceClasses, this stores the set of equivalent
+ /// types. Beyond EquivalenceClasses, it allows the user to specify
+ /// which element will act as leader through a StrictWeakOrdering
+ /// function.
+ template<typename ElemTy, typename StrictWeak>
+ class VISIBILITY_HIDDEN Synonyms {
+ std::map<ElemTy, unsigned> mapping;
+ std::vector<ElemTy> leaders;
+ StrictWeak swo;
+
+ public:
+ typedef unsigned iterator;
+ typedef const unsigned const_iterator;
+
+ // Inspection
+
+ bool empty() const {
+ return leaders.empty();
+ }
+
+ iterator findLeader(ElemTy e) {
+ typename std::map<ElemTy, unsigned>::iterator MI = mapping.find(e);
+ if (MI == mapping.end()) return 0;
+
+ return MI->second;
+ }
+
+ const_iterator findLeader(ElemTy e) const {
+ typename std::map<ElemTy, unsigned>::const_iterator MI =
+ mapping.find(e);
+ if (MI == mapping.end()) return 0;
+
+ return MI->second;
+ }
+
+ ElemTy &getLeader(iterator I) {
+ assert(I != 0 && "Element zero is out of range.");
+ return leaders[I-1];
+ }
+
+ const ElemTy &getLeader(const_iterator I) const {
+ assert(I != 0 && "Element zero is out of range.");
+ return leaders[I-1];
+ }
+
+#ifdef DEBUG
+ void debug(std::ostream &os) const {
+ for (unsigned i = 1, e = leaders.size()+1; i != e; ++i) {
+ os << i << ". " << *leaders[i-1] << ": [";
+ 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 << " ";
+ }
+ }
+ os << "]\n";
+ }
+ }
+#endif
+
+ // Mutators
+
+ /// 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 removed element.
+ iterator unionSets(ElemTy E1, ElemTy E2) {
+ if (swo(E1, E2)) std::swap(E1, E2);
+
+ iterator I1 = findLeader(E1);
+ iterator I2 = findLeader(E2);
+
+ if (!I1 && !I2) { // neither entry is in yet
+ leaders.push_back(E1);
+ I1 = leaders.size();
+ mapping[E1] = I1;
+ mapping[E2] = I1;
+ return false;
+ }
+
+ if (!I1 && I2) {
+ mapping[E1] = I2;
+ return false;
+ }
+
+ if (I1 && !I2) {
+ mapping[E2] = I1;
+ return false;
+ }
+
+ // 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 (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;
+ }
+
+ leaders.erase(leaders.begin() + I2 - 1);
+
+ return true;
+ }
+
+ /// 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;
+
+ leaders.push_back(e);
+ I = leaders.size();
+ mapping[e] = I;
+ return I;
+ }
+ };
+
/// Represents the set of equivalent Value*s and provides insertion
/// and fast lookup. Also stores the set of inequality relationships.
class PropertySet {
struct Property;
- class EquivalenceClasses<Value *> union_find;
public:
+ class Synonyms<Value *, compare> union_find;
+
typedef std::vector<Property>::iterator PropertyIterator;
typedef std::vector<Property>::const_iterator ConstPropertyIterator;
+ typedef Synonyms<Value *, compare>::iterator SynonymIterator;
enum Ops {
EQ,
@@ -98,10 +226,9 @@
}
Value *lookup(Value *V) const {
- EquivalenceClasses<Value *>::member_iterator SI =
- union_find.findLeader(V);
- if (SI == union_find.member_end()) return NULL;
- return *SI;
+ Synonyms<Value *, compare>::iterator SI = union_find.findLeader(V);
+ if (!SI) return NULL;
+ return union_find.getLeader(SI);
}
bool empty() const {
@@ -117,7 +244,18 @@
if (isa<Constant>(V2)) return; // refuse to set false == true.
DEBUG(std::cerr << "equal: " << *V1 << " and " << *V2 << "\n");
- union_find.unionSets(V1, V2);
+ 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;
+ }
+ }
addImpliedProperties(EQ, V1, V2);
}
@@ -130,7 +268,9 @@
return; // found.
// Add the property.
- Properties.push_back(Property(NE, V1, V2));
+ SynonymIterator I1 = union_find.findOrInsert(V1),
+ I2 = union_find.findOrInsert(V2);
+ Properties.push_back(Property(NE, I1, I2));
addImpliedProperties(NE, V1, V2);
}
@@ -138,22 +278,12 @@
assert(Opcode != EQ && "Can't findProperty on EQ."
"Use the lookup method instead.");
- V1 = canonicalize(V1);
- V2 = canonicalize(V2);
+ SynonymIterator I1 = union_find.findLeader(V1),
+ I2 = union_find.findLeader(V2);
+ if (!I1 || !I2) return Properties.end();
- // Does the property already exist?
- for (PropertyIterator I = Properties.begin(), E = Properties.end();
- I != E; ++I) {
- if (I->Opcode != Opcode) continue;
-
- I->V1 = canonicalize(I->V1);
- I->V2 = canonicalize(I->V2);
- if ((I->V1 == V1 && I->V2 == V2) ||
- (I->V1 == V2 && I->V2 == V1)) {
- return I; // Found.
- }
- }
- return Properties.end();
+ return
+ find(Properties.begin(), Properties.end(), Property(Opcode, I1, I2));
}
ConstPropertyIterator
@@ -161,35 +291,33 @@
assert(Opcode != EQ && "Can't findProperty on EQ."
"Use the lookup method instead.");
- V1 = canonicalize(V1);
- V2 = canonicalize(V2);
-
- // Does the property already exist?
- for (ConstPropertyIterator I = Properties.begin(),
- E = Properties.end(); I != E; ++I) {
- if (I->Opcode != Opcode) continue;
+ SynonymIterator I1 = union_find.findLeader(V1),
+ I2 = union_find.findLeader(V2);
+ if (!I1 || !I2) return Properties.end();
- Value *v1 = canonicalize(I->V1),
- *v2 = canonicalize(I->V2);
- if ((v1 == V1 && v2 == V2) ||
- (v1 == V2 && v2 == V1)) {
- return I; // Found.
- }
- }
- return Properties.end();
+ return
+ find(Properties.begin(), Properties.end(), Property(Opcode, I1, I2));
}
private:
// Represents Head OP [Tail1, Tail2, ...]
// For example: %x != %a, %x != %b.
- struct Property {
- Property(Ops opcode, Value *v1, Value *v2)
- : Opcode(opcode), V1(v1), V2(v2)
+ struct VISIBILITY_HIDDEN Property {
+ typedef Synonyms<Value *, compare>::iterator Iter;
+
+ 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."); }
+ "not a property."); }
+
+ bool operator==(const Property &P) const {
+ return (Opcode == P.Opcode) &&
+ ((I1 == P.I1 && I2 == P.I2) ||
+ (I1 == P.I2 && I2 == P.I1));
+ }
Ops Opcode;
- Value *V1, *V2;
+ Iter I1, I2;
};
void add(Ops Opcode, Value *V1, Value *V2, bool invert) {
@@ -207,7 +335,7 @@
}
}
- // Finds the properties implied by a equivalence and adds them too.
+ // 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) {
@@ -286,14 +414,15 @@
public:
#ifdef DEBUG
void debug(std::ostream &os) const {
- for (EquivalenceClasses<Value*>::iterator I = union_find.begin(),
- E = union_find.end(); I != E; ++I) {
- if (!I->isLeader()) continue;
- for (EquivalenceClasses<Value*>::member_iterator MI =
- union_find.member_begin(I); MI != union_find.member_end(); ++MI)
- std::cerr << **MI << " ";
- std::cerr << "\n--\n";
+ static const char *OpcodeTable[] = { "EQ", "NE" };
+
+ 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";
}
+ os << "\n";
}
#endif
@@ -319,22 +448,24 @@
// block to the next. Verifies that "current" dominates "next",
// then calls visitBasicBlock.
void proceedToSuccessor(PropertySet &CurrentPS, PropertySet &NextPS,
- DominatorTree::Node *Current, DominatorTree::Node *Next);
+ DTNodeType *Current, DTNodeType *Next);
void proceedToSuccessor(PropertySet &CurrentPS,
- DominatorTree::Node *Current, DominatorTree::Node *Next);
+ DTNodeType *Current, DTNodeType *Next);
// Visits each instruction in the basic block.
- void visitBasicBlock(DominatorTree::Node *DTNode,
- PropertySet &KnownProperties);
+ void visitBasicBlock(DTNodeType *DTNode, PropertySet &KnownProperties);
+ // Tries to simplify each Instruction and add new properties to
+ // the PropertySet. Returns true if it erase the instruction.
+ void visitInstruction(Instruction *I, DTNodeType *, PropertySet &);
// For each instruction, add the properties to KnownProperties.
- void visit(Instruction *I, DominatorTree::Node *, PropertySet &);
- void visit(TerminatorInst *TI, DominatorTree::Node *, PropertySet &);
- void visit(BranchInst *BI, DominatorTree::Node *, PropertySet &);
- void visit(SwitchInst *SI, DominatorTree::Node *, PropertySet);
- void visit(LoadInst *LI, DominatorTree::Node *, PropertySet &);
- void visit(StoreInst *SI, DominatorTree::Node *, PropertySet &);
- void visit(BinaryOperator *BO, DominatorTree::Node *, PropertySet &);
+
+ void visit(TerminatorInst *TI, DTNodeType *, PropertySet &);
+ void visit(BranchInst *BI, DTNodeType *, PropertySet &);
+ void visit(SwitchInst *SI, DTNodeType *, PropertySet);
+ void visit(LoadInst *LI, DTNodeType *, PropertySet &);
+ void visit(StoreInst *SI, DTNodeType *, PropertySet &);
+ void visit(BinaryOperator *BO, DTNodeType *, PropertySet &);
DominatorTree *DT;
bool modified;
@@ -421,18 +552,11 @@
if (SetCondInst *SCI = dyn_cast<SetCondInst>(BO))
return resolve(SCI, KP);
- DEBUG(std::cerr << "BO->getOperand(1) = " << *BO->getOperand(1) << "\n");
-
Value *lhs = resolve(BO->getOperand(0), KP),
*rhs = resolve(BO->getOperand(1), KP);
ConstantIntegral *CI1 = dyn_cast<ConstantIntegral>(lhs);
ConstantIntegral *CI2 = dyn_cast<ConstantIntegral>(rhs);
- DEBUG(std::cerr << "resolveBO: lhs = " << *lhs
- << ", rhs = " << *rhs << "\n");
- if (CI1) DEBUG(std::cerr << "CI1 = " << *CI1);
- if (CI2) DEBUG(std::cerr << "CI2 = " << *CI2);
-
if (!CI1 || !CI2) return BO;
Value *V = ConstantExpr::get(BO->getOpcode(), CI1, CI2);
@@ -464,27 +588,28 @@
return V;
}
-void PredicateSimplifier::visitBasicBlock(DominatorTree::Node *DTNode,
+void PredicateSimplifier::visitBasicBlock(DTNodeType *DTNode,
PropertySet &KnownProperties) {
BasicBlock *BB = DTNode->getBlock();
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E; ++I) {
- visit(I, DTNode, KnownProperties);
+ visitInstruction(I, DTNode, KnownProperties);
}
}
-void PredicateSimplifier::visit(Instruction *I, DominatorTree::Node *DTNode,
- PropertySet &KnownProperties) {
+void PredicateSimplifier::visitInstruction(Instruction *I,
+ DTNodeType *DTNode,
+ PropertySet &KnownProperties) {
+
DEBUG(std::cerr << "Considering instruction " << *I << "\n");
DEBUG(KnownProperties.debug(std::cerr));
- // Try to replace whole instruction.
+ // Try to replace the whole instruction.
Value *V = resolve(I, KnownProperties);
assert(V && "resolve not supposed to return NULL.");
if (V != I) {
modified = true;
++NumInstruction;
I->replaceAllUsesWith(V);
- I->eraseFromParent();
return;
}
@@ -513,8 +638,9 @@
}
void PredicateSimplifier::proceedToSuccessor(PropertySet &CurrentPS,
- PropertySet &NextPS, DominatorTree::Node *Current,
- DominatorTree::Node *Next) {
+ PropertySet &NextPS,
+ DTNodeType *Current,
+ DTNodeType *Next) {
if (Next->getBlock()->getSinglePredecessor() == Current->getBlock())
proceedToSuccessor(NextPS, Current, Next);
else
@@ -522,13 +648,14 @@
}
void PredicateSimplifier::proceedToSuccessor(PropertySet &KP,
- DominatorTree::Node *Current, DominatorTree::Node *Next) {
+ DTNodeType *Current,
+ DTNodeType *Next) {
if (Current->properlyDominates(Next))
visitBasicBlock(Next, KP);
}
-void PredicateSimplifier::visit(TerminatorInst *TI,
- DominatorTree::Node *Node, PropertySet &KP){
+void PredicateSimplifier::visit(TerminatorInst *TI, DTNodeType *Node,
+ PropertySet &KP) {
if (BranchInst *BI = dyn_cast<BranchInst>(TI)) {
visit(BI, Node, KP);
return;
@@ -545,8 +672,8 @@
}
}
-void PredicateSimplifier::visit(BranchInst *BI,
- DominatorTree::Node *Node, PropertySet &KP){
+void PredicateSimplifier::visit(BranchInst *BI, DTNodeType *Node,
+ PropertySet &KP) {
if (BI->isUnconditional()) {
proceedToSuccessor(KP, Node, DT->getNode(BI->getSuccessor(0)));
return;
@@ -586,33 +713,36 @@
proceedToSuccessor(KPcopy, FalseProperties, Node, DT->getNode(FalseDest));
}
-void PredicateSimplifier::visit(SwitchInst *SI,
- DominatorTree::Node *DTNode, PropertySet KP) {
+void PredicateSimplifier::visit(SwitchInst *SI, DTNodeType *DTNode,
+ PropertySet KP) {
Value *Condition = SI->getCondition();
- DEBUG(assert(Condition == KP.canonicalize(Condition) &&
- "Instruction wasn't already canonicalized?"));
+ assert(Condition == KP.canonicalize(Condition) &&
+ "Instruction wasn't already canonicalized?");
// If there's an NEProperty covering this SwitchInst, we may be able to
// eliminate one of the cases.
for (PropertySet::ConstPropertyIterator I = KP.Properties.begin(),
E = KP.Properties.end(); I != E; ++I) {
if (I->Opcode != PropertySet::NE) continue;
- Value *V1 = KP.canonicalize(I->V1),
- *V2 = KP.canonicalize(I->V2);
- if (V1 != Condition && V2 != Condition) continue;
-
- // Is one side a number?
- ConstantInt *CI = dyn_cast<ConstantInt>(KP.canonicalize(I->V1));
- if (!CI) CI = dyn_cast<ConstantInt>(KP.canonicalize(I->V2));
-
- if (CI) {
- unsigned i = SI->findCaseValue(CI);
- if (i != 0) {
- SI->getSuccessor(i)->removePredecessor(SI->getParent());
- SI->removeCase(i);
- modified = true;
- ++NumSwitchCases;
- }
+ Value *V1 = KP.union_find.getLeader(I->I1),
+ *V2 = KP.union_find.getLeader(I->I2);
+
+ // Find a Property with a ConstantInt on one side and our
+ // Condition on the other.
+ ConstantInt *CI = NULL;
+ if (V1 == Condition)
+ CI = dyn_cast<ConstantInt>(V2);
+ else if (V2 == Condition)
+ CI = dyn_cast<ConstantInt>(V1);
+
+ if (!CI) continue;
+
+ unsigned i = SI->findCaseValue(CI);
+ if (i != 0) { // zero is reserved for the default case.
+ SI->getSuccessor(i)->removePredecessor(SI->getParent());
+ SI->removeCase(i);
+ modified = true;
+ ++NumSwitchCases;
}
}
@@ -620,8 +750,8 @@
// and the NEProperties in the default BB.
PropertySet DefaultProperties(KP);
- DominatorTree::Node *Node = DT->getNode(SI->getParent()),
- *DefaultNode = DT->getNode(SI->getSuccessor(0));
+ DTNodeType *Node = DT->getNode(SI->getParent()),
+ *DefaultNode = DT->getNode(SI->getSuccessor(0));
if (!Node->dominates(DefaultNode)) DefaultNode = NULL;
for (unsigned I = 1, E = SI->getNumCases(); I < E; ++I) {
@@ -644,20 +774,20 @@
proceedToSuccessor(DefaultProperties, DTNode, DefaultNode);
}
-void PredicateSimplifier::visit(LoadInst *LI,
- DominatorTree::Node *, PropertySet &KP) {
+void PredicateSimplifier::visit(LoadInst *LI, DTNodeType *,
+ PropertySet &KP) {
Value *Ptr = LI->getPointerOperand();
KP.addNotEqual(Constant::getNullValue(Ptr->getType()), Ptr);
}
-void PredicateSimplifier::visit(StoreInst *SI,
- DominatorTree::Node *, PropertySet &KP) {
+void PredicateSimplifier::visit(StoreInst *SI, DTNodeType *,
+ PropertySet &KP) {
Value *Ptr = SI->getPointerOperand();
KP.addNotEqual(Constant::getNullValue(Ptr->getType()), Ptr);
}
-void PredicateSimplifier::visit(BinaryOperator *BO,
- DominatorTree::Node *, PropertySet &KP) {
+void PredicateSimplifier::visit(BinaryOperator *BO, DTNodeType *,
+ PropertySet &KP) {
Instruction::BinaryOps ops = BO->getOpcode();
switch (ops) {
@@ -670,8 +800,4 @@
default:
break;
}
-
- // Some other things we could do:
- // In f=x*y, if x != 1 && y != 1 then f != x && f != y.
- // In f=x+y, if x != 0 then f != y and if y != 0 then f != x.
}
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