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Resurrect r1.25. 

Fix and comment the "or", "and" and "xor" transformations.

llvm-svn: 31189
This commit is contained in:
Nick Lewycky 2006-10-25 23:48:24 +00:00
parent 0d4479b77d
commit 9d17c82a26
1 changed files with 154 additions and 117 deletions
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271
llvm/lib/Transforms/Scalar/PredicateSimplifier.cpp
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@ -41,6 +41,7 @@
#include "llvm/Support/Debug.h"
#include "llvm/Support/InstVisitor.h"
#include <iostream>
#include <list>
using namespace llvm;
typedef DominatorTree::Node DTNodeType;
@ -74,14 +75,14 @@ namespace {
return leaders.empty();
}
iterator findLeader(ElemTy e) {
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 {
const_iterator findLeader(ElemTy &e) const {
typename std::map<ElemTy, unsigned>::const_iterator MI =
mapping.find(e);
if (MI == mapping.end()) return 0;
@ -116,6 +117,11 @@ namespace {
// Mutators
void remove(ElemTy &e) {
ElemTy E = e; // The parameter to erase must not be a reference to
mapping.erase(E); // an element contained in the map.
}
/// 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
@ -124,7 +130,7 @@ namespace {
/// 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 findOrInsert(ElemTy &e) {
iterator I = findLeader(e);
if (I) return I;
@ -203,6 +209,19 @@ namespace {
return union_find.empty();
}
void remove(Value *V) {
SynonymIterator I = union_find.findLeader(V);
if (!I) return;
union_find.remove(V);
for (PropertyIterator PI = Properties.begin(), PE = Properties.end();
PI != PE;) {
Property &P = *PI++;
if (P.I1 == I || P.I2 == I) Properties.erase(PI);
}
}
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).
@ -211,6 +230,10 @@ namespace {
order(V1, V2);
if (isa<Constant>(V2)) return; // refuse to set false == true.
if (union_find.findLeader(V1) &&
union_find.findLeader(V1) == union_find.findLeader(V2))
return; // no-op
SynonymIterator deleted = union_find.unionSets(V1, V2);
if (deleted) {
SynonymIterator replacement = union_find.findLeader(V1);
@ -234,7 +257,7 @@ namespace {
if (isa<Constant>(V1) && isa<Constant>(V2)) return;
if (findProperty(NE, V1, V2) != Properties.end())
return; // found.
return; // no-op.
// Add the property.
SynonymIterator I1 = union_find.findOrInsert(V1),
@ -308,6 +331,73 @@ namespace {
}
}
void addToResolve(Value *V, std::list<Value *> &WorkList) {
if (!isa<Constant>(V) && !isa<BasicBlock>(V)) {
for (Value::use_iterator UI = V->use_begin(), UE = V->use_end();
UI != UE; ++UI) {
if (!isa<Constant>(*UI) && !isa<BasicBlock>(*UI)) {
WorkList.push_back(*UI);
}
}
}
}
void resolve(std::list<Value *> &WorkList) {
if (WorkList.empty()) return;
Value *V = WorkList.front();
WorkList.pop_front();
if (empty()) return;
Instruction *I = dyn_cast<Instruction>(V);
if (!I) return;
if (BinaryOperator *BO = dyn_cast<BinaryOperator>(I)) {
Value *lhs = canonicalize(BO->getOperand(0)),
*rhs = canonicalize(BO->getOperand(1));
ConstantIntegral *CI1 = dyn_cast<ConstantIntegral>(lhs),
*CI2 = dyn_cast<ConstantIntegral>(rhs);
if (CI1 && CI2) {
addToResolve(BO, WorkList);
addEqual(BO, ConstantExpr::get(BO->getOpcode(), CI1, CI2));
} else if (SetCondInst *SCI = dyn_cast<SetCondInst>(BO)) {
PropertySet::ConstPropertyIterator NE =
findProperty(PropertySet::NE, lhs, rhs);
if (NE != Properties.end()) {
switch (SCI->getOpcode()) {
case Instruction::SetEQ:
addToResolve(SCI, WorkList);
addEqual(SCI, ConstantBool::getFalse());
break;
case Instruction::SetNE:
addToResolve(SCI, WorkList);
addEqual(SCI, ConstantBool::getTrue());
break;
case Instruction::SetLE:
case Instruction::SetGE:
case Instruction::SetLT:
case Instruction::SetGT:
break;
default:
assert(0 && "Unknown opcode in SetCondInst.");
break;
}
}
}
} else if (SelectInst *SI = dyn_cast<SelectInst>(I)) {
Value *Condition = canonicalize(SI->getCondition());
if (ConstantBool *CB = dyn_cast<ConstantBool>(Condition)) {
addToResolve(SI, WorkList);
addEqual(SI, CB->getValue() ? SI->getTrueValue() : SI->getFalseValue());
}
}
if (!WorkList.empty()) resolve(WorkList);
}
// 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)
@ -334,38 +424,65 @@ namespace {
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);
case Instruction::And: {
// "and int %a, %b" EQ 0xff then %a EQ 0xff and %b EQ 0xff
// "and bool %a, %b" EQ true then %a EQ true and %b EQ true
// "and bool %a, %b" NE false then %a EQ true and %b EQ true
if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V1)) {
if (Opcode == EQ && CI->isAllOnesValue()) {
addEqual(CI, BO->getOperand(0));
addEqual(CI, BO->getOperand(1));
} else if (Opcode == NE && CI == ConstantBool::getFalse()) {
addEqual(ConstantBool::getTrue(), BO->getOperand(0));
addEqual(ConstantBool::getTrue(), BO->getOperand(1));
}
}
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::Or: {
// "or int %a, %b" EQ 0 then %a EQ 0 and %b EQ 0
// "or bool %a, %b" EQ false then %a EQ false and %b EQ false
// "or bool %a, %b" NE true then %a EQ false and %b EQ false
if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V1)) {
if (Opcode == EQ && CI->isNullValue()) {
addEqual(CI, BO->getOperand(0));
addEqual(CI, BO->getOperand(1));
} else if (Opcode == NE && CI == ConstantBool::getTrue()) {
addEqual(ConstantBool::getFalse(), BO->getOperand(0));
addEqual(ConstantBool::getFalse(), BO->getOperand(1));
}
}
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);
} break;
case Instruction::Xor: {
// "xor bool true, %a" EQ true then %a = false
// "xor bool true, %a" EQ false then %a = true
// "xor bool false, %a" EQ true then %a = true
// "xor bool false, %a" EQ false then %a = false
// 1. Repeat all of the above, with "NE false" in place of
// "EQ true" and "NE true" in place of "EQ false".
// "xor int %c, %a" EQ %c then %a = 0
// "xor int %c, %a" NE %c then %a != 0
// 2. Repeat all of the above, with the operands swapped.
Value *LHS = BO->getOperand(0), *RHS = BO->getOperand(1);
if (!isa<Constant>(LHS)) std::swap(LHS, RHS);
if (ConstantBool *CB = dyn_cast<ConstantBool>(V1)) {
if (ConstantBool *A = dyn_cast<ConstantBool>(LHS)) {
addEqual(RHS, ConstantBool::get(A->getValue() ^ CB->getValue()
^ Opcode==NE));
}
}
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);
else if (ConstantIntegral *CI = dyn_cast<ConstantIntegral>(V1)) {
if (ConstantIntegral *A = dyn_cast<ConstantIntegral>(LHS)) {
if (A == CI)
add(Opcode, RHS, Constant::getNullValue(A->getType()), false);
}
}
break;
} break;
default:
break;
}
} else if (SelectInst *SI = dyn_cast<SelectInst>(V2)) {
if (Opcode != EQ && Opcode != NE) return;
ConstantBool *True = ConstantBool::get(Opcode==EQ),
*False = ConstantBool::get(Opcode!=EQ);
@ -373,9 +490,12 @@ namespace {
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.");
}
std::list<Value *> WorkList;
addToResolve(V1, WorkList);
addToResolve(V2, WorkList);
resolve(WorkList);
}
DominatorTree *DT;
@ -400,32 +520,12 @@ namespace {
/// 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 VISIBILITY_HIDDEN PredicateSimplifier : public FunctionPass {
class PredicateSimplifier : public FunctionPass {
public:
bool runOnFunction(Function &F);
virtual void getAnalysisUsage(AnalysisUsage &AU) const;
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);
public:
explicit Backwards(const PropertySet &KP) : KP(KP) {}
Value *resolve(Value *V);
};
/// 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
@ -540,69 +640,6 @@ void PredicateSimplifier::getAnalysisUsage(AnalysisUsage &AU) const {
AU.addPreservedID(BreakCriticalEdgesID);
}
Value &PredicateSimplifier::Backwards::visitSetCondInst(SetCondInst &SCI) {
Value &vBO = visitBinaryOperator(SCI);
if (&vBO != &SCI) return vBO;
Value *SCI0 = resolve(SCI.getOperand(0)),
*SCI1 = resolve(SCI.getOperand(1));
PropertySet::ConstPropertyIterator NE =
KP.findProperty(PropertySet::NE, SCI0, SCI1);
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;
}
Value &PredicateSimplifier::Backwards::visitBinaryOperator(BinaryOperator &BO) {
Value *V = KP.canonicalize(&BO);
if (V != &BO) return *V;
Value *lhs = resolve(BO.getOperand(0)),
*rhs = resolve(BO.getOperand(1));
ConstantIntegral *CI1 = dyn_cast<ConstantIntegral>(lhs),
*CI2 = dyn_cast<ConstantIntegral>(rhs);
if (CI1 && CI2) return *ConstantExpr::get(BO.getOpcode(), CI1, CI2);
return BO;
}
Value &PredicateSimplifier::Backwards::visitSelectInst(SelectInst &SI) {
Value *V = KP.canonicalize(&SI);
if (V != &SI) return *V;
Value *Condition = resolve(SI.getCondition());
if (ConstantBool *CB = dyn_cast<ConstantBool>(Condition))
return *resolve(CB->getValue() ? SI.getTrueValue() : SI.getFalseValue());
return SI;
}
Value &PredicateSimplifier::Backwards::visitInstruction(Instruction &I) {
return *KP.canonicalize(&I);
}
Value *PredicateSimplifier::Backwards::resolve(Value *V) {
if (isa<Constant>(V) || isa<BasicBlock>(V) || KP.empty()) return V;
if (Instruction *I = dyn_cast<Instruction>(V)) return &visit(*I);
return KP.canonicalize(V);
}
void PredicateSimplifier::visitBasicBlock(BasicBlock *BB,
PropertySet &KnownProperties) {
for (BasicBlock::iterator I = BB->begin(), E = BB->end(); I != E;) {
@ -613,12 +650,12 @@ void PredicateSimplifier::visitBasicBlock(BasicBlock *BB,
void PredicateSimplifier::visitInstruction(Instruction *I,
PropertySet &KnownProperties) {
// Try to replace the whole instruction.
Backwards resolve(KnownProperties);
Value *V = resolve.resolve(I);
Value *V = KnownProperties.canonicalize(I);
if (V != I) {
modified = true;
++NumInstruction;
DEBUG(std::cerr << "Removing " << *I);
KnownProperties.remove(I);
I->replaceAllUsesWith(V);
I->eraseFromParent();
return;
@ -627,7 +664,7 @@ void PredicateSimplifier::visitInstruction(Instruction *I,
// Try to substitute operands.
for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) {
Value *Oper = I->getOperand(i);
Value *V = resolve.resolve(Oper);
Value *V = KnownProperties.canonicalize(Oper);
if (V != Oper) {
modified = true;
++NumVarsReplaced;