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-rw-r--r--lib/Transforms/Scalar/Reassociate.cpp31
1 files changed, 23 insertions, 8 deletions
diff --git a/lib/Transforms/Scalar/Reassociate.cpp b/lib/Transforms/Scalar/Reassociate.cpp
index 986d6a4..ea2cf7c 100644
--- a/lib/Transforms/Scalar/Reassociate.cpp
+++ b/lib/Transforms/Scalar/Reassociate.cpp
@@ -1368,11 +1368,10 @@ Value *Reassociate::OptimizeXor(Instruction *I,
Value *Reassociate::OptimizeAdd(Instruction *I,
SmallVectorImpl<ValueEntry> &Ops) {
// Scan the operand lists looking for X and -X pairs. If we find any, we
- // can simplify the expression. X+-X == 0. While we're at it, scan for any
+ // can simplify expressions like X+-X == 0 and X+~X ==-1. While we're at it,
+ // scan for any
// duplicates. We want to canonicalize Y+Y+Y+Z -> 3*Y+Z.
- //
- // TODO: We could handle "X + ~X" -> "-1" if we wanted, since "-X = ~X+1".
- //
+
for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
Value *TheOp = Ops[i].Op;
// Check to see if we've seen this operand before. If so, we factor all
@@ -1412,19 +1411,28 @@ Value *Reassociate::OptimizeAdd(Instruction *I,
continue;
}
- // Check for X and -X in the operand list.
- if (!BinaryOperator::isNeg(TheOp))
+ // Check for X and -X or X and ~X in the operand list.
+ if (!BinaryOperator::isNeg(TheOp) && !BinaryOperator::isNot(TheOp))
continue;
- Value *X = BinaryOperator::getNegArgument(TheOp);
+ Value *X = nullptr;
+ if (BinaryOperator::isNeg(TheOp))
+ X = BinaryOperator::getNegArgument(TheOp);
+ else if (BinaryOperator::isNot(TheOp))
+ X = BinaryOperator::getNotArgument(TheOp);
+
unsigned FoundX = FindInOperandList(Ops, i, X);
if (FoundX == i)
continue;
// Remove X and -X from the operand list.
- if (Ops.size() == 2)
+ if (Ops.size() == 2 && BinaryOperator::isNeg(TheOp))
return Constant::getNullValue(X->getType());
+ // Remove X and ~X from the operand list.
+ if (Ops.size() == 2 && BinaryOperator::isNot(TheOp))
+ return Constant::getAllOnesValue(X->getType());
+
Ops.erase(Ops.begin()+i);
if (i < FoundX)
--FoundX;
@@ -1434,6 +1442,13 @@ Value *Reassociate::OptimizeAdd(Instruction *I,
++NumAnnihil;
--i; // Revisit element.
e -= 2; // Removed two elements.
+
+ // if X and ~X we append -1 to the operand list.
+ if (BinaryOperator::isNot(TheOp)) {
+ Value *V = Constant::getAllOnesValue(X->getType());
+ Ops.insert(Ops.end(), ValueEntry(getRank(V), V));
+ e += 1;
+ }
}
// Scan the operand list, checking to see if there are any common factors