From 27ce855378a80dff680c2989800af1f4e69975fe Mon Sep 17 00:00:00 2001
From: Adrian Kummerlaender
Date: Sat, 9 Nov 2019 20:21:27 +0100
Subject: Implement basic version of the SSS pattern for C++ target

An interesting extension of the AA pattern.  The main advantage of this is
that updating pointers in a control structure is  much more elegant than
duplicating all function implementations as is required by the normal AA
pattern. For more details see [1].

Only works for the SOA layout.

On a pure memory access level this pattern is equivalent to the AA pattern.
The difference is how the memory locations are calculated (by pointer swap
& shift or by different indexing functions for odd and even time steps).

[1]: "An auto-vectorization friendly parallel lattice Boltzmann streaming
      scheme for direct addressing" by Mohrhard et al. (2019)
---
 boltzgen/kernel/template/pattern/SSS.cpp.mako | 55 +++++++++++++++++++++++++++
 1 file changed, 55 insertions(+)
 create mode 100644 boltzgen/kernel/template/pattern/SSS.cpp.mako

(limited to 'boltzgen/kernel/template/pattern')

diff --git a/boltzgen/kernel/template/pattern/SSS.cpp.mako b/boltzgen/kernel/template/pattern/SSS.cpp.mako
new file mode 100644
index 0000000..a60b03a
--- /dev/null
+++ b/boltzgen/kernel/template/pattern/SSS.cpp.mako
@@ -0,0 +1,55 @@
+<%def name="operator(name, params = None)">
+<%
+if layout.__class__.__name__ != 'SOA':
+    raise Exception('SSS pattern only works for the AOS memory layout')
+%>
+void ${name}(
+      ${float_type}** f
+    , std::size_t gid
+% if params is not None:
+% for param_type, param_name in params:
+    , ${param_type} ${param_name}
+% endfor
+% endif
+) {
+% for i, c_i in enumerate(descriptor.c):
+    ${float_type}* preshifted_f_${i} = f[${i}] + ${layout.cell_preshift('gid')};
+% endfor
+
+% for i, c_i in enumerate(descriptor.c):
+    const ${float_type} f_curr_${i} = *preshifted_f_${i};
+% endfor
+
+    ${caller.body()}
+
+% for i, c_i in enumerate(descriptor.c):
+    *preshifted_f_${i} = f_next_${descriptor.c.index(-c_i)};
+% endfor
+}
+</%def>
+
+<%def name="functor(name, params = None)">
+<%
+if layout.__class__.__name__ != 'SOA':
+    raise Exception('SSS pattern only works for the AOS memory layout')
+%>
+void ${name}(
+      ${float_type}** f
+    , std::size_t gid
+% if params is not None:
+% for param_type, param_name in params:
+    , ${param_type} ${param_name}
+% endfor
+% endif
+) {
+% for i, c_i in enumerate(descriptor.c):
+    const ${float_type}* preshifted_f_${i} = f[${i}] + ${layout.cell_preshift('gid')};
+% endfor
+
+% for i, c_i in enumerate(descriptor.c):
+    const ${float_type} f_curr_${i} = *preshifted_f_${descriptor.c.index(-c_i)};
+% endfor
+
+    ${caller.body()}
+}
+</%def>
-- 
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