From 668a3b9c66678d4a49766e98923142a96fd8d4ff Mon Sep 17 00:00:00 2001
From: Szymon Prajs <szymon.overton@gmail.com>
Date: Tue, 23 Dec 2025 09:46:38 +0000
Subject: [PATCH] Add convolve separable benchmark

---
 benchmarks/convolve_separable.py | 64 ++++++++++++++++++++++++++++++++
 1 file changed, 64 insertions(+)
 create mode 100644 benchmarks/convolve_separable.py

diff --git a/benchmarks/convolve_separable.py b/benchmarks/convolve_separable.py
new file mode 100644
index 0000000000..650663a90b
--- /dev/null
+++ b/benchmarks/convolve_separable.py
@@ -0,0 +1,64 @@
+"""ASV-style benchmark for separable-kernel convolve performance."""
+
+import contextlib
+import importlib
+import inspect
+
+import numpy as np
+
+from astropy.convolution import convolve
+
+IMAGE_SIZES = [128, 256, 512]
+KERNEL_SIZES = [11, 21, 31]
+BOUNDARIES = ["fill"]
+
+
+def _make_gaussian_1d(size, sigma=None):
+    if size % 2 == 0:
+        raise ValueError("Kernel size must be odd.")
+    if sigma is None:
+        sigma = size / 6.0
+    x = np.arange(size, dtype=float) - size // 2
+    kernel = np.exp(-(x * x) / (2.0 * sigma * sigma))
+    kernel /= kernel.sum()
+    return kernel
+
+
+@contextlib.contextmanager
+def _disable_separable_fast_path(convolve_mod):
+    original = convolve_mod._factor_separable_kernel_2d
+    convolve_mod._factor_separable_kernel_2d = lambda _kernel: None
+    try:
+        yield
+    finally:
+        convolve_mod._factor_separable_kernel_2d = original
+
+
+class ConvolveSeparable2D:
+    params = (IMAGE_SIZES, KERNEL_SIZES, BOUNDARIES)
+    param_names = ["image_size", "kernel_size", "boundary"]
+
+    def setup(self, image_size, kernel_size, boundary):
+        rng = np.random.default_rng(12345)
+        self.array = rng.random((image_size, image_size))
+        k1d = _make_gaussian_1d(kernel_size)
+        self.kernel = np.outer(k1d, k1d)
+        self.boundary = boundary
+
+        self._has_method_kw = "method" in inspect.signature(convolve).parameters
+        self._convolve_mod = None
+        if not self._has_method_kw:
+            self._convolve_mod = importlib.import_module("astropy.convolution.convolve")
+
+    def time_convolve_separable_fast(self, image_size, kernel_size, boundary):
+        if self._has_method_kw:
+            convolve(self.array, self.kernel, boundary=boundary, method="separable")
+        else:
+            convolve(self.array, self.kernel, boundary=boundary)
+
+    def time_convolve_separable_baseline(self, image_size, kernel_size, boundary):
+        if self._has_method_kw:
+            convolve(self.array, self.kernel, boundary=boundary, method="direct")
+        else:
+            with _disable_separable_fast_path(self._convolve_mod):
+                convolve(self.array, self.kernel, boundary=boundary)