ValueTracking: Teach isKnownToBeAPowerOfTwo about (ADD X, (XOR X, Y)) where X is a power of two
This allows us to simplify urem instructions involving the add+xor to
turn into simpler math.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185272 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index d2e13b7..39bc1a3 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -855,16 +855,24 @@
return false;
}
- // Adding a power of two to the same power of two is a power of two or zero.
- if (OrZero && match(V, m_Add(m_Value(X), m_Value(Y)))) {
- if (match(X, m_And(m_Value(), m_Specific(Y)))) {
- if (isKnownToBeAPowerOfTwo(Y, /*OrZero*/true, Depth))
- return true;
- } else if (match(Y, m_And(m_Value(), m_Specific(X)))) {
- if (isKnownToBeAPowerOfTwo(X, /*OrZero*/true, Depth))
- return true;
- }
- }
+ if (match(V, m_Add(m_Value(X), m_Value(Y))))
+ if (OverflowingBinaryOperator *VOBO = cast<OverflowingBinaryOperator>(V))
+ if (OrZero || VOBO->hasNoUnsignedWrap() || VOBO->hasNoSignedWrap()) {
+ // Adding a power of two to the same power of two is a power of two or
+ // zero.
+ if (BinaryOperator *XBO = dyn_cast<BinaryOperator>(X))
+ if (XBO->getOpcode() == Instruction::And ||
+ XBO->getOpcode() == Instruction::Xor)
+ if (XBO->getOperand(0) == Y || XBO->getOperand(1) == Y)
+ if (isKnownToBeAPowerOfTwo(Y, /*OrZero*/true, Depth))
+ return true;
+ if (BinaryOperator *YBO = dyn_cast<BinaryOperator>(Y))
+ if (YBO->getOpcode() == Instruction::And ||
+ YBO->getOpcode() == Instruction::Xor)
+ if (YBO->getOperand(0) == X || YBO->getOperand(1) == X)
+ if (isKnownToBeAPowerOfTwo(X, /*OrYero*/true, Depth))
+ return true;
+ }
// An exact divide or right shift can only shift off zero bits, so the result
// is a power of two only if the first operand is a power of two and not