From 3c7e5499dda197acc0c6a41e3447424e8045f041 Mon Sep 17 00:00:00 2001
From: Joris Van den Bossche <jorisvandenbossche@gmail.com>
Date: Thu, 10 Jun 2021 09:10:21 +0200
Subject: [PATCH] PERF: fix regression in reductions for boolean/integer data
 (assume no missing values)

---
 pandas/core/nanops.py | 8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

diff --git a/pandas/core/nanops.py b/pandas/core/nanops.py
index 673c482bced18..85c54b02be60c 100644
--- a/pandas/core/nanops.py
+++ b/pandas/core/nanops.py
@@ -245,7 +245,8 @@ def _maybe_get_mask(
     """
     if mask is None:
         if is_bool_dtype(values.dtype) or is_integer_dtype(values.dtype):
-            return np.broadcast_to(False, values.shape)
+            # Boolean data cannot contain nulls, so signal via mask being None
+            return None
 
         if skipna or needs_i8_conversion(values.dtype):
             mask = isna(values)
@@ -1449,7 +1450,10 @@ def _maybe_null_out(
                 result[null_mask] = None
     elif result is not NaT:
         if check_below_min_count(shape, mask, min_count):
-            result = np.nan
+            if isinstance(result, np.ndarray):
+                result = np.broadcast_to(np.nan, result.shape)
+            else:
+                result = np.nan
 
     return result