[InstCombine] Shift amount reassociation in bittest: drop pointless one-use restriction

That one-use restriction is not needed for correctness - we have already
ensured that one of the shifts will go away, so we know we won't increase
the instruction count. So there is no need for that restriction.

llvm-svn: 368518
diff --git a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
index ddbc170..edad6a4 100644
--- a/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
+++ b/llvm/lib/Transforms/InstCombine/InstCombineCompares.cpp
@@ -3318,8 +3318,8 @@
                      m_CombineAnd(m_AnyLogicalShift, m_Value(YShift)))))
     return nullptr;
 
-  // If YShift is a single-use 'lshr', swap the shifts around.
-  if (match(YShift, m_OneUse(m_AnyLShr)))
+  // If YShift is a 'lshr', swap the shifts around.
+  if (match(YShift, m_AnyLShr))
     std::swap(XShift, YShift);
 
   // The shifts must be in opposite directions.