[llvm-commits] [llvm] r92363 - /llvm/trunk/lib/Transforms/Scalar/Reassociate.cpp
Chris Lattner
sabre at nondot.org
Thu Dec 31 10:17:13 PST 2009
Author: lattner
Date: Thu Dec 31 12:17:13 2009
New Revision: 92363
URL: http://llvm.org/viewvc/llvm-project?rev=92363&view=rev
Log:
move the rest of the add optimization code out to OptimizeAdd,
improve some comments, simplify a bit of code.
Modified:
llvm/trunk/lib/Transforms/Scalar/Reassociate.cpp
Modified: llvm/trunk/lib/Transforms/Scalar/Reassociate.cpp
URL: http://llvm.org/viewvc/llvm-project/llvm/trunk/lib/Transforms/Scalar/Reassociate.cpp?rev=92363&r1=92362&r2=92363&view=diff
==============================================================================
--- llvm/trunk/lib/Transforms/Scalar/Reassociate.cpp (original)
+++ llvm/trunk/lib/Transforms/Scalar/Reassociate.cpp Thu Dec 31 12:17:13 2009
@@ -92,7 +92,7 @@
void RewriteExprTree(BinaryOperator *I, std::vector<ValueEntry> &Ops,
unsigned Idx = 0);
Value *OptimizeExpression(BinaryOperator *I, std::vector<ValueEntry> &Ops);
- Value *OptimizeAdd(std::vector<ValueEntry> &Ops);
+ Value *OptimizeAdd(Instruction *I, std::vector<ValueEntry> &Ops);
void LinearizeExprTree(BinaryOperator *I, std::vector<ValueEntry> &Ops);
void LinearizeExpr(BinaryOperator *I);
Value *RemoveFactorFromExpression(Value *V, Value *Factor);
@@ -598,7 +598,7 @@
/// OptimizeAdd - Optimize a series of operands to an 'add' instruction. This
/// optimizes based on identities. If it can be reduced to a single Value, it
/// is returned, otherwise the Ops list is mutated as necessary.
-Value *Reassociate::OptimizeAdd(std::vector<ValueEntry> &Ops) {
+Value *Reassociate::OptimizeAdd(Instruction *I, std::vector<ValueEntry> &Ops) {
// Scan the operand lists looking for X and -X pairs. If we find any, we
// can simplify the expression. X+-X == 0.
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
@@ -626,6 +626,94 @@
--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.
+ SmallPtrSet<BinaryOperator*, 4> Multiplies;
+ unsigned MaxOcc = 0;
+ Value *MaxOccVal = 0;
+ for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
+ BinaryOperator *BOp = dyn_cast<BinaryOperator>(Ops[i].Op);
+ if (BOp == 0 || BOp->getOpcode() != Instruction::Mul || !BOp->use_empty())
+ continue;
+
+ // If we've already seen this multiply, don't revisit it.
+ if (!Multiplies.insert(BOp)) continue;
+
+ // Compute all of the factors of this added value.
+ SmallVector<Value*, 8> Factors;
+ FindSingleUseMultiplyFactors(BOp, Factors);
+ assert(Factors.size() > 1 && "Bad linearize!");
+
+ // Add one to FactorOccurrences for each unique factor in this op.
+ if (Factors.size() == 2) {
+ unsigned Occ = ++FactorOccurrences[Factors[0]];
+ if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factors[0]; }
+ if (Factors[0] != Factors[1]) { // Don't double count A*A.
+ Occ = ++FactorOccurrences[Factors[1]];
+ if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factors[1]; }
+ }
+ } else {
+ SmallPtrSet<Value*, 4> Duplicates;
+ for (unsigned i = 0, e = Factors.size(); i != e; ++i) {
+ if (!Duplicates.insert(Factors[i])) continue;
+
+ unsigned Occ = ++FactorOccurrences[Factors[i]];
+ if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factors[i]; }
+ }
+ }
+ }
+
+ // If any factor occurred more than one time, we can pull it out.
+ if (MaxOcc > 1) {
+ DEBUG(errs() << "\nFACTORING [" << MaxOcc << "]: " << *MaxOccVal << "\n");
+ ++NumFactor;
+
+ // 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
+ // RemoveFactorFromExpression on successive values to behave differently.
+ Instruction *DummyInst = BinaryOperator::CreateAdd(MaxOccVal, MaxOccVal);
+ SmallVector<Value*, 4> NewMulOps;
+ for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
+ if (Value *V = RemoveFactorFromExpression(Ops[i].Op, MaxOccVal)) {
+ NewMulOps.push_back(V);
+ Ops.erase(Ops.begin()+i);
+ --i; --e;
+ }
+ }
+
+ // No need for extra uses anymore.
+ delete DummyInst;
+
+ unsigned NumAddedValues = NewMulOps.size();
+ Value *V = EmitAddTreeOfValues(I, NewMulOps);
+ Value *V2 = BinaryOperator::CreateMul(V, MaxOccVal, "tmp", I);
+
+ // Now that we have inserted V and its sole use, optimize it. This allows
+ // us to handle cases that require multiple factoring steps, such as this:
+ // A*A*B + A*A*C --> A*(A*B+A*C) --> A*(A*(B+C))
+ if (NumAddedValues > 1)
+ ReassociateExpression(cast<BinaryOperator>(V));
+
+ // 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 fact, such as
+ // "A*B + A*C + D" -> "A*(B+C) + D". Add the new multiply to the list of
+ // things being added.
+ Ops.insert(Ops.begin(), ValueEntry(getRank(V2), V2));
+ }
+
return 0;
}
@@ -692,98 +780,11 @@
case Instruction::Add: {
unsigned NumOps = Ops.size();
- if (Value *Result = OptimizeAdd(Ops))
+ if (Value *Result = OptimizeAdd(I, Ops))
return Result;
IterateOptimization |= Ops.size() != NumOps;
}
- // 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.
- SmallPtrSet<BinaryOperator*, 4> Multiplies;
- unsigned MaxOcc = 0;
- Value *MaxOccVal = 0;
- for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
- BinaryOperator *BOp = dyn_cast<BinaryOperator>(Ops[i].Op);
- if (BOp == 0 || BOp->getOpcode() != Instruction::Mul || !BOp->use_empty())
- continue;
-
- // If we've already seen this multiply, don't revisit it.
- if (!Multiplies.insert(BOp)) continue;
-
- // Compute all of the factors of this added value.
- SmallVector<Value*, 8> Factors;
- FindSingleUseMultiplyFactors(BOp, Factors);
- assert(Factors.size() > 1 && "Bad linearize!");
-
- // Add one to FactorOccurrences for each unique factor in this op.
- if (Factors.size() == 2) {
- unsigned Occ = ++FactorOccurrences[Factors[0]];
- if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factors[0]; }
- if (Factors[0] != Factors[1]) { // Don't double count A*A.
- Occ = ++FactorOccurrences[Factors[1]];
- if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factors[1]; }
- }
- } else {
- SmallPtrSet<Value*, 4> Duplicates;
- for (unsigned i = 0, e = Factors.size(); i != e; ++i) {
- if (!Duplicates.insert(Factors[i])) continue;
-
- unsigned Occ = ++FactorOccurrences[Factors[i]];
- if (Occ > MaxOcc) { MaxOcc = Occ; MaxOccVal = Factors[i]; }
- }
- }
- }
-
- // 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
- // RemoveFactorFromExpression on successive values to behave differently.
- Instruction *DummyInst = BinaryOperator::CreateAdd(MaxOccVal, MaxOccVal);
- SmallVector<Value*, 4> NewMulOps;
- for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
- if (Value *V = RemoveFactorFromExpression(Ops[i].Op, MaxOccVal)) {
- NewMulOps.push_back(V);
- Ops.erase(Ops.begin()+i);
- --i; --e;
- }
- }
-
- // No need for extra uses anymore.
- delete DummyInst;
-
- unsigned NumAddedValues = NewMulOps.size();
- Value *V = EmitAddTreeOfValues(I, NewMulOps);
- Value *V2 = BinaryOperator::CreateMul(V, MaxOccVal, "tmp", I);
-
- // Now that we have inserted V and its sole use, optimize it. This allows
- // us to handle cases that require multiple factoring steps, such as this:
- // A*A*B + A*A*C --> A*(A*B+A*C) --> A*(A*(B+C))
- if (NumAddedValues > 1)
- ReassociateExpression(cast<BinaryOperator>(V));
-
- ++NumFactor;
-
- if (Ops.empty())
- return V2;
-
- // Add the new value to the list of things being added.
- Ops.insert(Ops.begin(), ValueEntry(getRank(V2), V2));
-
- // Rewrite the tree so that there is now a use of V.
- RewriteExprTree(I, Ops);
- return OptimizeExpression(I, Ops);
- }
break;
//case Instruction::Mul:
}
@@ -854,7 +855,7 @@
std::vector<ValueEntry> Ops;
LinearizeExprTree(I, Ops);
- DEBUG(errs() << "RAIn:\t"; PrintOps(I, Ops); errs() << "\n");
+ DEBUG(errs() << "RAIn:\t"; PrintOps(I, Ops); errs() << '\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
@@ -869,7 +870,7 @@
if (Value *V = OptimizeExpression(I, Ops)) {
// This expression tree simplified to something that isn't a tree,
// eliminate it.
- DEBUG(errs() << "Reassoc to scalar: " << *V << "\n");
+ DEBUG(errs() << "Reassoc to scalar: " << *V << '\n');
I->replaceAllUsesWith(V);
RemoveDeadBinaryOp(I);
++NumAnnihil;
@@ -888,7 +889,7 @@
Ops.pop_back();
}
- DEBUG(errs() << "RAOut:\t"; PrintOps(I, Ops); errs() << "\n");
+ DEBUG(errs() << "RAOut:\t"; PrintOps(I, Ops); errs() << '\n');
if (Ops.size() == 1) {
// This expression tree simplified to something that isn't a tree,
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