From 0c2c2d401312cfbaf05b0278a21e9c70cb48c717 Mon Sep 17 00:00:00 2001
From: Andreas Kloeckner <inform@tiker.net>
Date: Sun, 25 Oct 2020 14:28:02 -0500
Subject: [PATCH] Handle empty reductions (Closes gh-330)
---
pyopencl/reduction.py | 8 +++++++-
test/test_algorithm.py | 10 ++++++++--
2 files changed, 15 insertions(+), 3 deletions(-)
diff --git a/pyopencl/reduction.py b/pyopencl/reduction.py
index 00995450..6eebe729 100644
--- a/pyopencl/reduction.py
+++ b/pyopencl/reduction.py
@@ -386,10 +386,16 @@ class ReductionKernel:
else:
allocator = repr_vec.allocator
- if sz <= stage_inf.group_size*SMALL_SEQ_COUNT*MAX_GROUP_COUNT:
+ if sz == 0:
+ result = empty(use_queue, (), self.dtype_out, allocator=allocator)
+ group_count = 1
+ seq_count = 0
+
+ elif sz <= stage_inf.group_size*SMALL_SEQ_COUNT*MAX_GROUP_COUNT:
total_group_size = SMALL_SEQ_COUNT*stage_inf.group_size
group_count = (sz + total_group_size - 1) // total_group_size
seq_count = SMALL_SEQ_COUNT
+
else:
group_count = MAX_GROUP_COUNT
macrogroup_size = group_count*stage_inf.group_size
diff --git a/test/test_algorithm.py b/test/test_algorithm.py
index 660c7dfc..353af281 100644
--- a/test/test_algorithm.py
+++ b/test/test_algorithm.py
@@ -247,15 +247,21 @@ def test_sum(ctx_factory):
slice(1000, -3000),
slice(1000, None),
slice(1000, None, 3),
+ slice(1000, 1000),
]:
sum_a = np.sum(a[slc])
+ if sum_a:
+ ref_divisor = abs(sum_a)
+ else:
+ ref_divisor = 1
+
if slc.step is None:
sum_a_gpu = cl_array.sum(a_gpu[slc]).get()
- assert abs(sum_a_gpu - sum_a) / abs(sum_a) < 1e-4
+ assert abs(sum_a_gpu - sum_a) / ref_divisor < 1e-4
sum_a_gpu_2 = cl_array.sum(a_gpu, slice=slc).get()
- assert abs(sum_a_gpu_2 - sum_a) / abs(sum_a) < 1e-4
+ assert abs(sum_a_gpu_2 - sum_a) / ref_divisor < 1e-4
def test_sum_without_data(ctx_factory):
--
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