}
}
#endif
-
+
namespace {
/// \brief Utility class representing a base and exponent pair which form one
/// factor of some product.
void LinearizeExpr(BinaryOperator *I);
Value *RemoveFactorFromExpression(Value *V, Value *Factor);
void ReassociateInst(BasicBlock::iterator &BBI);
-
+
void RemoveDeadBinaryOp(Value *V);
};
}
Instruction *Op = dyn_cast<Instruction>(V);
if (!Op || !isa<BinaryOperator>(Op))
return;
-
+
Value *LHS = Op->getOperand(0), *RHS = Op->getOperand(1);
-
+
ValueRankMap.erase(Op);
DeadInsts.push_back(Op);
RemoveDeadBinaryOp(LHS);
RemoveDeadBinaryOp(RHS);
}
-
static bool isUnmovableInstruction(Instruction *I) {
if (I->getOpcode() == Instruction::PHI ||
I->getOpcode() == Instruction::Alloca ||
I->getOpcode() == Instruction::Invoke ||
(I->getOpcode() == Instruction::Call &&
!isa<DbgInfoIntrinsic>(I)) ||
- I->getOpcode() == Instruction::UDiv ||
+ I->getOpcode() == Instruction::UDiv ||
I->getOpcode() == Instruction::SDiv ||
I->getOpcode() == Instruction::FDiv ||
I->getOpcode() == Instruction::URem ||
LinearizeExpr(I);
}
-
/// LinearizeExprTree - Given an associative binary expression tree, traverse
/// all of the uses putting it into canonical form. This forces a left-linear
/// form of the expression (((a+b)+c)+d), and collects information about the
// such, just remember these operands and their rank.
Ops.push_back(ValueEntry(getRank(LHS), LHS));
Ops.push_back(ValueEntry(getRank(RHS), RHS));
-
+
// Clear the leaves out.
I->setOperand(0, UndefValue::get(I->getType()));
I->setOperand(1, UndefValue::get(I->getType()));
return;
}
-
+
// Turn X+(Y+Z) -> (Y+Z)+X
std::swap(LHSBO, RHSBO);
std::swap(LHS, RHS);
// Remember the RHS operand and its rank.
Ops.push_back(ValueEntry(getRank(RHS), RHS));
-
+
// Clear the RHS leaf out.
I->setOperand(1, UndefValue::get(I->getType()));
}
DEBUG(dbgs() << "TO: " << *I << '\n');
MadeChange = true;
++NumChanged;
-
+
// If we reassociated a tree to fewer operands (e.g. (1+a+2) -> (a+3)
// delete the extra, now dead, nodes.
RemoveDeadBinaryOp(OldLHS);
MadeChange = true;
++NumChanged;
}
-
+
BinaryOperator *LHS = cast<BinaryOperator>(I->getOperand(0));
assert(LHS->getOpcode() == I->getOpcode() &&
"Improper expression tree!");
-
+
// Compactify the tree instructions together with each other to guarantee
// that the expression tree is dominated by all of Ops.
LHS->moveBefore(I);
RewriteExprTree(LHS, Ops, i+1);
}
-
-
-// NegateValue - Insert instructions before the instruction pointed to by BI,
-// that computes the negative version of the value specified. The negative
-// version of the value is returned, and BI is left pointing at the instruction
-// that should be processed next by the reassociation pass.
-//
+/// NegateValue - Insert instructions before the instruction pointed to by BI,
+/// that computes the negative version of the value specified. The negative
+/// version of the value is returned, and BI is left pointing at the instruction
+/// that should be processed next by the reassociation pass.
static Value *NegateValue(Value *V, Instruction *BI) {
if (Constant *C = dyn_cast<Constant>(V))
return ConstantExpr::getNeg(C);
-
+
// We are trying to expose opportunity for reassociation. One of the things
// that we want to do to achieve this is to push a negation as deep into an
// expression chain as possible, to expose the add instructions. In practice,
// We must move the add instruction here, because the neg instructions do
// not dominate the old add instruction in general. By moving it, we are
- // assured that the neg instructions we just inserted dominate the
+ // assured that the neg instructions we just inserted dominate the
// instruction we are about to insert after them.
//
I->moveBefore(BI);
I->setName(I->getName()+".neg");
return I;
}
-
+
// Okay, we need to materialize a negated version of V with an instruction.
// Scan the use lists of V to see if we have one already.
for (Value::use_iterator UI = V->use_begin(), E = V->use_end(); UI != E;++UI){
// Verify that the negate is in this function, V might be a constant expr.
if (TheNeg->getParent()->getParent() != BI->getParent()->getParent())
continue;
-
+
BasicBlock::iterator InsertPt;
if (Instruction *InstInput = dyn_cast<Instruction>(V)) {
if (InvokeInst *II = dyn_cast<InvokeInst>(InstInput)) {
// If this is a negation, we can't split it up!
if (BinaryOperator::isNeg(Sub))
return false;
-
+
// Don't bother to break this up unless either the LHS is an associable add or
// subtract or if this is only used by one.
if (isReassociableOp(Sub->getOperand(0), Instruction::Add) ||
if (isReassociableOp(Sub->getOperand(1), Instruction::Add) ||
isReassociableOp(Sub->getOperand(1), Instruction::Sub))
return true;
- if (Sub->hasOneUse() &&
+ if (Sub->hasOneUse() &&
(isReassociableOp(Sub->use_back(), Instruction::Add) ||
isReassociableOp(Sub->use_back(), Instruction::Sub)))
return true;
-
+
return false;
}
// If an operand of this shift is a reassociable multiply, or if the shift
// is used by a reassociable multiply or add, turn into a multiply.
if (isReassociableOp(Shl->getOperand(0), Instruction::Mul) ||
- (Shl->hasOneUse() &&
+ (Shl->hasOneUse() &&
(isReassociableOp(Shl->use_back(), Instruction::Mul) ||
isReassociableOp(Shl->use_back(), Instruction::Add)))) {
Constant *MulCst = ConstantInt::get(Shl->getType(), 1);
MulCst = ConstantExpr::getShl(MulCst, cast<Constant>(Shl->getOperand(1)));
-
+
Instruction *Mul =
BinaryOperator::CreateMul(Shl->getOperand(0), MulCst, "", Shl);
ValueRankMap.erase(Shl);
return 0;
}
-// Scan backwards and forwards among values with the same rank as element i to
-// see if X exists. If X does not exist, return i. This is useful when
-// scanning for 'x' when we see '-x' because they both get the same rank.
+/// FindInOperandList - Scan backwards and forwards among values with the same
+/// rank as element i to see if X exists. If X does not exist, return i. This
+/// is useful when scanning for 'x' when we see '-x' because they both get the
+/// same rank.
static unsigned FindInOperandList(SmallVectorImpl<ValueEntry> &Ops, unsigned i,
Value *X) {
unsigned XRank = Ops[i].Rank;
static Value *EmitAddTreeOfValues(Instruction *I,
SmallVectorImpl<WeakVH> &Ops){
if (Ops.size() == 1) return Ops.back();
-
+
Value *V1 = Ops.back();
Ops.pop_back();
Value *V2 = EmitAddTreeOfValues(I, Ops);
return BinaryOperator::CreateAdd(V2, V1, "tmp", I);
}
-/// RemoveFactorFromExpression - If V is an expression tree that is a
+/// RemoveFactorFromExpression - If V is an expression tree that is a
/// multiplication sequence, and if this sequence contains a multiply by Factor,
/// remove Factor from the tree and return the new tree.
Value *Reassociate::RemoveFactorFromExpression(Value *V, Value *Factor) {
BinaryOperator *BO = isReassociableOp(V, Instruction::Mul);
if (!BO) return 0;
-
+
SmallVector<ValueEntry, 8> Factors;
LinearizeExprTree(BO, Factors);
Factors.erase(Factors.begin()+i);
break;
}
-
+
// If this is a negative version of this factor, remove it.
if (ConstantInt *FC1 = dyn_cast<ConstantInt>(Factor))
if (ConstantInt *FC2 = dyn_cast<ConstantInt>(Factors[i].Op))
break;
}
}
-
+
if (!FoundFactor) {
// Make sure to restore the operands to the expression tree.
RewriteExprTree(BO, Factors);
return 0;
}
-
+
BasicBlock::iterator InsertPt = BO; ++InsertPt;
-
+
// If this was just a single multiply, remove the multiply and return the only
// remaining operand.
if (Factors.size() == 1) {
RewriteExprTree(BO, Factors);
V = BO;
}
-
+
if (NeedsNegate)
V = BinaryOperator::CreateNeg(V, "neg", InsertPt);
-
+
return V;
}
Factors.push_back(V);
return;
}
-
+
// If this value has a single use because it is another input to the add
// tree we're reassociating and we dropped its use, it actually has two
// uses and we can't factor it.
return;
}
}
-
-
+
+
// Otherwise, add the LHS and RHS to the list of factors.
FindSingleUseMultiplyFactors(BO->getOperand(1), Factors, Ops, false);
FindSingleUseMultiplyFactors(BO->getOperand(0), Factors, Ops, false);
if (FoundX != i) {
if (Opcode == Instruction::And) // ...&X&~X = 0
return Constant::getNullValue(X->getType());
-
+
if (Opcode == Instruction::Or) // ...|X|~X = -1
return Constant::getAllOnesValue(X->getType());
}
}
-
+
// Next, check for duplicate pairs of values, which we assume are next to
// each other, due to our sorting criteria.
assert(i < Ops.size());
++NumAnnihil;
continue;
}
-
+
// Drop pairs of values for Xor.
assert(Opcode == Instruction::Xor);
if (e == 2)
return Constant::getNullValue(Ops[0].Op->getType());
-
+
// Y ^ X^X -> Y
Ops.erase(Ops.begin()+i, Ops.begin()+i+2);
i -= 1; e -= 2;
Ops.erase(Ops.begin()+i);
++NumFound;
} while (i != Ops.size() && Ops[i].Op == TheOp);
-
+
DEBUG(errs() << "\nFACTORING [" << NumFound << "]: " << *TheOp << '\n');
++NumFactor;
-
+
// Insert a new multiply.
Value *Mul = ConstantInt::get(cast<IntegerType>(I->getType()), NumFound);
Mul = BinaryOperator::CreateMul(TheOp, Mul, "factor", I);
-
+
// Now that we have inserted a multiply, optimize it. This allows us to
// handle cases that require multiple factoring steps, such as this:
// (X*2) + (X*2) + (X*2) -> (X*2)*3 -> X*6
RedoInsts.push_back(Mul);
-
+
// If every add operand was a duplicate, return the multiply.
if (Ops.empty())
return Mul;
-
+
// Otherwise, we had some input that didn't have the dupe, such as
// "A + A + B" -> "A*2 + B". Add the new multiply to the list of
// things being added by this operation.
Ops.insert(Ops.begin(), ValueEntry(getRank(Mul), Mul));
-
+
--i;
e = Ops.size();
continue;
}
-
+
// Check for X and -X in the operand list.
if (!BinaryOperator::isNeg(TheOp))
continue;
-
+
Value *X = BinaryOperator::getNegArgument(TheOp);
unsigned FoundX = FindInOperandList(Ops, i, X);
if (FoundX == i)
continue;
-
+
// Remove X and -X from the operand list.
if (Ops.size() == 2)
return Constant::getNullValue(X->getType());
-
+
Ops.erase(Ops.begin()+i);
if (i < FoundX)
--FoundX;
--i; // Revisit element.
e -= 2; // Removed two elements.
}
-
+
// Scan the operand list, checking to see if there are any common factors
// between operands. Consider something like A*A+A*B*C+D. We would like to
// reassociate this to A*(A+B*C)+D, which reduces the number of multiplies.
// To efficiently find this, we count the number of times a factor occurs
// for any ADD operands that are MULs.
DenseMap<Value*, unsigned> FactorOccurrences;
-
+
// Keep track of each multiply we see, to avoid triggering on (X*4)+(X*4)
// where they are actually the same multiply.
unsigned MaxOcc = 0;
BinaryOperator *BOp = dyn_cast<BinaryOperator>(Ops[i].Op);
if (BOp == 0 || BOp->getOpcode() != Instruction::Mul || !BOp->use_empty())
continue;
-
+
// Compute all of the factors of this added value.
SmallVector<Value*, 8> Factors;
FindSingleUseMultiplyFactors(BOp, Factors, Ops, true);
assert(Factors.size() > 1 && "Bad linearize!");
-
+
// Add one to FactorOccurrences for each unique factor in this op.
SmallPtrSet<Value*, 8> Duplicates;
for (unsigned i = 0, e = Factors.size(); i != e; ++i) {
Value *Factor = Factors[i];
if (!Duplicates.insert(Factor)) continue;
-
+
unsigned Occ = ++FactorOccurrences[Factor];
if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factor; }
-
+
// If Factor is a negative constant, add the negated value as a factor
// because we can percolate the negate out. Watch for minint, which
// cannot be positivified.
Factor = ConstantInt::get(CI->getContext(), -CI->getValue());
assert(!Duplicates.count(Factor) &&
"Shouldn't have two constant factors, missed a canonicalize");
-
+
unsigned Occ = ++FactorOccurrences[Factor];
if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factor; }
}
}
}
-
+
// If any factor occurred more than one time, we can pull it out.
if (MaxOcc > 1) {
DEBUG(errs() << "\nFACTORING [" << MaxOcc << "]: " << *MaxOccVal << '\n');
// Create a new instruction that uses the MaxOccVal twice. If we don't do
// this, we could otherwise run into situations where removing a factor
- // from an expression will drop a use of maxocc, and this can cause
+ // from an expression will drop a use of maxocc, and this can cause
// RemoveFactorFromExpression on successive values to behave differently.
Instruction *DummyInst = BinaryOperator::CreateAdd(MaxOccVal, MaxOccVal);
SmallVector<WeakVH, 4> NewMulOps;
BinaryOperator *BOp = dyn_cast<BinaryOperator>(Ops[i].Op);
if (BOp == 0 || BOp->getOpcode() != Instruction::Mul || !BOp->use_empty())
continue;
-
+
if (Value *V = RemoveFactorFromExpression(Ops[i].Op, MaxOccVal)) {
// The factorized operand may occur several times. Convert them all in
// one fell swoop.
--i;
}
}
-
+
// No need for extra uses anymore.
delete DummyInst;
// Rerun associate on the multiply in case the inner expression turned into
// a multiply. We want to make sure that we keep things in canonical form.
V2 = ReassociateExpression(cast<BinaryOperator>(V2));
-
+
// If every add operand included the factor (e.g. "A*B + A*C"), then the
// entire result expression is just the multiply "A*(B+C)".
if (Ops.empty())
return V2;
-
+
// Otherwise, we had some input that didn't have the factor, such as
// "A*B + A*C + D" -> "A*(B+C) + D". Add the new multiply to the list of
// things being added by this operation.
Ops.insert(Ops.begin(), ValueEntry(getRank(V2), V2));
}
-
+
return 0;
}
if (Ops.size() == 1) return Ops[0].Op;
unsigned Opcode = I->getOpcode();
-
+
if (Constant *V1 = dyn_cast<Constant>(Ops[Ops.size()-2].Op))
if (Constant *V2 = dyn_cast<Constant>(Ops.back().Op)) {
Ops.pop_back();
++NumAnnihil;
return CstVal;
}
-
+
if (cast<ConstantInt>(CstVal)->isOne())
Ops.pop_back(); // X * 1 -> X
break;
return 0;
}
-
/// ReassociateInst - Inspect and reassociate the instruction at the
/// given position, post-incrementing the position.
void Reassociate::ReassociateInst(BasicBlock::iterator &BBI) {
}
// Reject cases where it is pointless to do this.
- if (!isa<BinaryOperator>(BI) || BI->getType()->isFloatingPointTy() ||
+ if (!isa<BinaryOperator>(BI) || BI->getType()->isFloatingPointTy() ||
BI->getType()->isVectorTy())
return; // Floating point ops are not associative.
if (I->hasOneUse() && isReassociableOp(I->use_back(), I->getOpcode()))
return;
- // If this is an add tree that is used by a sub instruction, ignore it
+ // If this is an add tree that is used by a sub instruction, ignore it
// until we process the subtract.
if (I->hasOneUse() && I->getOpcode() == Instruction::Add &&
cast<Instruction>(I->use_back())->getOpcode() == Instruction::Sub)
}
Value *Reassociate::ReassociateExpression(BinaryOperator *I) {
-
+
// First, walk the expression tree, linearizing the tree, collecting the
// operand information.
SmallVector<ValueEntry, 8> Ops;
LinearizeExprTree(I, Ops);
-
+
DEBUG(dbgs() << "RAIn:\t"; PrintOps(I, Ops); dbgs() << '\n');
-
+
// Now that we have linearized the tree to a list and have gathered all of
// the operands and their ranks, sort the operands by their rank. Use a
// stable_sort so that values with equal ranks will have their relative
// this sorts so that the highest ranking values end up at the beginning of
// the vector.
std::stable_sort(Ops.begin(), Ops.end());
-
+
// OptimizeExpression - Now that we have the expression tree in a convenient
// sorted form, optimize it globally if possible.
if (Value *V = OptimizeExpression(I, Ops)) {
++NumAnnihil;
return V;
}
-
+
// We want to sink immediates as deeply as possible except in the case where
// this is a multiply tree used only by an add, and the immediate is a -1.
// In this case we reassociate to put the negation on the outside so that we
ValueEntry Tmp = Ops.pop_back_val();
Ops.insert(Ops.begin(), Tmp);
}
-
+
DEBUG(dbgs() << "RAOut:\t"; PrintOps(I, Ops); dbgs() << '\n');
-
+
if (Ops.size() == 1) {
// This expression tree simplified to something that isn't a tree,
// eliminate it.
RemoveDeadBinaryOp(I);
return Ops[0].Op;
}
-
+
// Now that we ordered and optimized the expressions, splat them back into
// the expression tree, removing any unneeded nodes.
RewriteExprTree(I, Ops);
return I;
}
-
bool Reassociate::runOnFunction(Function &F) {
// Recalculate the rank map for F
BuildRankMap(F);
ValueRankMap.clear();
return MadeChange;
}
-
projects / oota-llvm.git / commitdiff