From c7646489c973a962e1154d0c5d5bf38c7e9d8d6d Mon Sep 17 00:00:00 2001
From: Andreas Kloeckner <inform@tiker.net>
Date: Sun, 8 May 2016 20:15:39 -0500
Subject: [PATCH] Initial batch of CL function descriptions

---
 loopy/target/opencl.py | 20 ++++++++++++++++++++
 test/test_loopy.py     | 17 +++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/loopy/target/opencl.py b/loopy/target/opencl.py
index f083a70b..5cb6fbc1 100644
--- a/loopy/target/opencl.py
+++ b/loopy/target/opencl.py
@@ -137,6 +137,11 @@ def _register_vector_types(dtype_registry):
 
 # {{{ function mangler
 
+_CL_SIMPLE_MULTI_ARG_FUNCTIONS = {
+        "clamp": 3,
+        }
+
+
 def opencl_function_mangler(kernel, name, arg_dtypes):
     if not isinstance(name, str):
         return None
@@ -160,6 +165,21 @@ def opencl_function_mangler(kernel, name, arg_dtypes):
         scalar_dtype, offset, field_name = arg_dtypes[0].numpy_dtype.fields["s0"]
         return NumpyType(scalar_dtype), name
 
+    if name in _CL_SIMPLE_MULTI_ARG_FUNCTIONS:
+        num_args = _CL_SIMPLE_MULTI_ARG_FUNCTIONS[name]
+        if len(arg_dtypes) != num_args:
+            raise LoopyError("%s takes %d arguments (%d received)"
+                    % (name, num_args, len(arg_dtypes)))
+
+        dtype = np.find_common_type(
+                [], [dtype.numpy_dtype for dtype in arg_dtypes])
+
+        if dtype.kind == "c":
+            raise LoopyError("%s does not support complex numbers"
+                    % name)
+
+        return NumpyType(dtype), name
+
     return None
 
 # }}}
diff --git a/test/test_loopy.py b/test/test_loopy.py
index cebbda4d..96286b73 100644
--- a/test/test_loopy.py
+++ b/test/test_loopy.py
@@ -2473,6 +2473,23 @@ def test_atomic(ctx_factory, dtype):
     lp.auto_test_vs_ref(ref_knl, ctx, knl, parameters=dict(n=10000))
 
 
+def test_clamp(ctx_factory):
+    ctx = ctx_factory()
+    queue = cl.CommandQueue(ctx)
+
+    n = 15 * 10**6
+    x = cl.clrandom.rand(queue, n, dtype=np.float32)
+
+    knl = lp.make_kernel(
+            "{ [i]: 0<=i<n }",
+            "out[i] = clamp(x[i], a, b)")
+
+    knl = lp.split_iname(knl, "i", 128, outer_tag="g.0", inner_tag="l.0")
+    knl = lp.set_options(knl, write_cl=True)
+
+    evt, (out,) = knl(queue, x=x, a=np.float32(12), b=np.float32(15))
+
+
 if __name__ == "__main__":
     if len(sys.argv) > 1:
         exec(sys.argv[1])
-- 
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