From 9c529e3cf982e390af1ef0db44f05feddd103656 Mon Sep 17 00:00:00 2001
From: Andreas Kloeckner <inform@tiker.net>
Date: Wed, 5 Oct 2016 18:17:36 -0500
Subject: [PATCH] Add a regression test guarding against a cache collision

---
 test/test_loopy.py | 14 ++++++++++++++
 1 file changed, 14 insertions(+)

diff --git a/test/test_loopy.py b/test/test_loopy.py
index cd6305e57..a204c666c 100644
--- a/test/test_loopy.py
+++ b/test/test_loopy.py
@@ -1342,6 +1342,20 @@ def test_regression_no_ret_call_removal(ctx_factory):
     assert len(knl.instructions) == 3
 
 
+def test_regression_persistent_hash():
+    knl1 = lp.make_kernel(
+            "{[i] : 0<=i<n}",
+            "cse_exprvar = d[2]*d[2]")
+
+    knl2 = lp.make_kernel(
+            "{[i] : 0<=i<n}",
+            "cse_exprvar = d[0]*d[0]")
+    from loopy.tools import LoopyKeyBuilder
+    lkb = LoopyKeyBuilder()
+    assert lkb(knl1.instructions[0]) != lkb(knl2.instructions[0])
+    assert lkb(knl1) != lkb(knl2)
+
+
 if __name__ == "__main__":
     if len(sys.argv) > 1:
         exec(sys.argv[1])
-- 
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