From e43a20db66934e6b90be21395dd9cf21b9703253 Mon Sep 17 00:00:00 2001
From: Dominic Kempf <dominic.kempf@iwr.uni-heidelberg.de>
Date: Tue, 11 Oct 2016 15:39:37 +0200
Subject: [PATCH] Add identity propagation transformation
---
.../transformations/identitypropagation.py | 71 +++++++++++++++++++
1 file changed, 71 insertions(+)
create mode 100644 python/dune/perftool/ufl/transformations/identitypropagation.py
diff --git a/python/dune/perftool/ufl/transformations/identitypropagation.py b/python/dune/perftool/ufl/transformations/identitypropagation.py
new file mode 100644
index 00000000..2e7bbab5
--- /dev/null
+++ b/python/dune/perftool/ufl/transformations/identitypropagation.py
@@ -0,0 +1,71 @@
+"""
+A transformation to help the form splitting algorithm split
+vector and tensor expressions. In a nutshell does:
+\sum_i f(i)I(i,k) => f(k)
+"""
+
+from dune.perftool.ufl.transformations import ufl_transformation
+
+from ufl.algorithms import MultiFunction
+from ufl.classes import Identity, Index, IntValue, MultiIndex
+
+
+class GetIndexMap(MultiFunction):
+ call = MultiFunction.__call__
+
+ def __call__(self, o):
+ self.free_index = Index(o.ufl_free_indices[0])
+ self.replacemap = {}
+ self.call(o)
+ return self.replacemap
+
+ def expr(self, o):
+ for op in o.ufl_operands:
+ self.call(op)
+
+ def indexed(self, o):
+ op, i = o.ufl_operands
+ if isinstance(op, Identity):
+ assert(len(i) == 2)
+ assert(self.free_index in i)
+ ind, = set(i) - {self.free_index}
+ self.replacemap[ind] = self.free_index
+ else:
+ self.call(op)
+
+
+class IdentityPropagation(MultiFunction):
+ call = MultiFunction.__call__
+
+ def __call__(self, expr):
+ self.replacemap = GetIndexMap()(expr)
+ return self.call(expr)
+
+ def expr(self, o):
+ return self.reuse_if_untouched(o, *tuple(self.call(op) for op in o.ufl_operands))
+
+ def indexed(self, o):
+ op, i = o.ufl_operands
+ if isinstance(op, Identity):
+ return IntValue(1)
+ else:
+ return self.reuse_if_untouched(o, self.call(op), self.call(i))
+
+ def multi_index(self, o):
+ return MultiIndex(tuple(self.replacemap.get(i, i) for i in o))
+
+ def index_sum(self, o):
+ op, i = o.ufl_operands
+
+ if i[0] in self.replacemap:
+ return self.call(op)
+ else:
+ return self.reuse_if_untouched(o, self.call(op), self.call(i))
+
+
+@ufl_transformation(name='identity')
+def identity_propagation(expr):
+ if expr.ufl_free_indices:
+ return IdentityPropagation()(expr)
+ else:
+ return expr
--
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