Fix INT_MIN gotcha pointed out by Eli Friedman.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@128028 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Analysis/ValueTracking.cpp b/lib/Analysis/ValueTracking.cpp
index c36f68c..0f4bfb7 100644
--- a/lib/Analysis/ValueTracking.cpp
+++ b/lib/Analysis/ValueTracking.cpp
@@ -725,9 +725,10 @@
isPowerOfTwo(SI->getFalseValue(), TD, Depth);
// 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.
- if (match(V, m_Shr(m_Value(), m_Value())) ||
- match(V, m_IDiv(m_Value(), m_Value()))) {
+ // is a power of two only if the first operand is a power of two and not
+ // copying a sign bit (sdiv int_min, 2).
+ if (match(V, m_LShr(m_Value(), m_Value())) ||
+ match(V, m_UDiv(m_Value(), m_Value()))) {
BinaryOperator *BO = cast<BinaryOperator>(V);
if (BO->isExact())
return isPowerOfTwo(BO->getOperand(0), TD, Depth);