From 2735ccbf6eeda84ede9df6208e524169a43d3cda Mon Sep 17 00:00:00 2001
From: Kaushik Kulkarni <kaushikcfd@gmail.com>
Date: Mon, 1 Feb 2021 17:46:16 -0600
Subject: [PATCH] [statistics]: ensure count_insn(insn) == 1 if
 len(insn.within_inames) == 0

---
 loopy/statistics.py     | 42 +++++++++++++++++++++++++++--------------
 test/test_statistics.py | 20 ++++++++++++++++++++
 2 files changed, 48 insertions(+), 14 deletions(-)

diff --git a/loopy/statistics.py b/loopy/statistics.py
index a0a0f9c7e..72ec4d586 100755
--- a/loopy/statistics.py
+++ b/loopy/statistics.py
@@ -56,6 +56,17 @@ __doc__ = """
 """
 
 
+def get_kernel_parameter_space(kernel):
+    return isl.Space.create_from_names(kernel.isl_context,
+            set=[], params=sorted(list(kernel.outer_params()))).params()
+
+
+def get_kernel_zero_pwqpolynomial(kernel):
+    space = get_kernel_parameter_space(kernel)
+    space = space.insert_dims(dim_type.out, 0, 1)
+    return isl.PwQPolynomial.zero(space)
+
+
 # {{{ GuardedPwQPolynomial
 
 class GuardedPwQPolynomial:
@@ -1231,7 +1242,7 @@ def count(kernel, set, space=None):
     return add_assumptions_guard(kernel, count)
 
 
-def get_unused_hw_axes_factor(knl, insn, disregard_local_axes, space=None):
+def get_unused_hw_axes_factor(knl, insn, disregard_local_axes):
     # FIXME: Multi-kernel support
     gsize, lsize = knl.get_grid_size_upper_bounds()
 
@@ -1250,12 +1261,12 @@ def get_unused_hw_axes_factor(knl, insn, disregard_local_axes, space=None):
                 g_used.add(tag.axis)
 
     def mult_grid_factor(used_axes, size):
-        result = 1
+        result = get_kernel_zero_pwqpolynomial(knl) + 1
+
         for iaxis, size in enumerate(size):
             if iaxis not in used_axes:
                 if not isinstance(size, int):
-                    if space is not None:
-                        size = size.align_params(space)
+                    size = size.align_params(result.space)
 
                     size = isl.PwQPolynomial.from_pw_aff(size)
 
@@ -1271,6 +1282,17 @@ def get_unused_hw_axes_factor(knl, insn, disregard_local_axes, space=None):
     return add_assumptions_guard(knl, result)
 
 
+def count_inames_domain(knl, inames):
+    space = get_kernel_parameter_space(knl)
+    if not inames:
+        return add_assumptions_guard(knl,
+                get_kernel_zero_pwqpolynomial(knl) + 1)
+
+    inames_domain = knl.get_inames_domain(inames)
+    domain = inames_domain.project_out_except(inames, [dim_type.set])
+    return count(knl, domain, space=space)
+
+
 def count_insn_runs(knl, insn, count_redundant_work, disregard_local_axes=False):
 
     insn_inames = insn.within_inames
@@ -1281,19 +1303,11 @@ def count_insn_runs(knl, insn, count_redundant_work, disregard_local_axes=False)
                 for iname in insn_inames
                 if not knl.iname_tags_of_type(iname, LocalIndexTag)]
 
-    inames_domain = knl.get_inames_domain(insn_inames)
-    domain = (inames_domain.project_out_except(
-                            insn_inames, [dim_type.set]))
-
-    space = isl.Space.create_from_names(isl.DEFAULT_CONTEXT,
-            set=[], params=knl.outer_params())
-
-    c = count(knl, domain, space=space)
+    c = count_inames_domain(knl, insn_inames)
 
     if count_redundant_work:
         unused_fac = get_unused_hw_axes_factor(knl, insn,
-                        disregard_local_axes=disregard_local_axes,
-                        space=space)
+                        disregard_local_axes=disregard_local_axes)
         return c * unused_fac
     else:
         return c
diff --git a/test/test_statistics.py b/test/test_statistics.py
index bcdc542cb..d6ad5874d 100644
--- a/test/test_statistics.py
+++ b/test/test_statistics.py
@@ -1319,6 +1319,26 @@ def test_strided_footprint():
     assert 2*num < denom
 
 
+def test_no_loop_ops():
+    # See https://github.com/inducer/loopy/issues/211
+
+    knl = lp.make_kernel(
+        "{ : }",
+        """
+        c = a + b
+        d = 2*c + a + b
+        """)
+
+    knl = lp.add_dtypes(knl, {"a": np.float, "b": np.float})
+
+    op_map = lp.get_op_map(knl, subgroup_size=SGS, count_redundant_work=True,
+                           count_within_subscripts=True)
+    f64_add = op_map.filter_by(name="add").eval_and_sum({})
+    f64_mul = op_map.filter_by(name="mul").eval_and_sum({})
+    assert f64_add == 3
+    assert f64_mul == 1
+
+
 if __name__ == "__main__":
     if len(sys.argv) > 1:
         exec(sys.argv[1])
-- 
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