From d5373ec85aa4f689c82ecc7fb96d0a600f35de5c Mon Sep 17 00:00:00 2001
From: Martin Bauer <martin.bauer@fau.de>
Date: Fri, 16 Nov 2018 10:14:42 +0100
Subject: [PATCH] Fix for LB collide only step
- sweep updates pdf field in place, but does not load all the values
before overwriting them
-> added a new transformation on AssignmentCollection that loads all
read values first
---
simp/__init__.py | 5 +++--
simp/simplifications.py | 20 ++++++++++++++++++++
2 files changed, 23 insertions(+), 2 deletions(-)
diff --git a/simp/__init__.py b/simp/__init__.py
index 0e8a85d1f..36efb062d 100644
--- a/simp/__init__.py
+++ b/simp/__init__.py
@@ -2,9 +2,10 @@ from .assignment_collection import AssignmentCollection
from .simplificationstrategy import SimplificationStrategy
from .simplifications import sympy_cse, sympy_cse_on_assignment_list, \
apply_to_all_assignments, apply_on_all_subexpressions, subexpression_substitution_in_existing_subexpressions, \
- subexpression_substitution_in_main_assignments, add_subexpressions_for_divisions
+ subexpression_substitution_in_main_assignments, add_subexpressions_for_divisions, add_subexpressions_for_field_reads
__all__ = ['AssignmentCollection', 'SimplificationStrategy',
'sympy_cse', 'sympy_cse_on_assignment_list', 'apply_to_all_assignments',
'apply_on_all_subexpressions', 'subexpression_substitution_in_existing_subexpressions',
- 'subexpression_substitution_in_main_assignments', 'add_subexpressions_for_divisions']
+ 'subexpression_substitution_in_main_assignments', 'add_subexpressions_for_divisions',
+ 'add_subexpressions_for_field_reads']
diff --git a/simp/simplifications.py b/simp/simplifications.py
index 076adf967..a42601b52 100644
--- a/simp/simplifications.py
+++ b/simp/simplifications.py
@@ -1,5 +1,7 @@
import sympy as sp
from typing import Callable, List
+
+from pystencils import Field
from pystencils.assignment import Assignment
from pystencils.simp.assignment_collection import AssignmentCollection
from pystencils.sympyextensions import subs_additive
@@ -83,6 +85,24 @@ def add_subexpressions_for_divisions(ac: AC) -> AC:
return ac.new_with_substitutions(substitutions, True)
+def add_subexpressions_for_field_reads(ac: AC, subexpressions=True, main_assignments=True) -> AC:
+ r"""Substitutes field accesses on rhs of assignments with subexpressions
+
+ Can change semantics of the update rule (which is the goal of this transformation)
+ This is useful if a field should be update in place - all values are loaded before into subexpression variables,
+ then the new values are computed and written to the same field in-place.
+ """
+ field_reads = set()
+ if subexpressions:
+ for assignment in ac.subexpressions:
+ field_reads.update(assignment.rhs.atoms(Field.Access))
+ if main_assignments:
+ for assignment in ac.main_assignments:
+ field_reads.update(assignment.rhs.atoms(Field.Access))
+ substitutions = {fa: sp.Dummy() for fa in field_reads}
+ return ac.new_with_substitutions(substitutions, add_substitutions_as_subexpressions=True, substitute_on_lhs=False)
+
+
def apply_to_all_assignments(operation: Callable[[sp.Expr], sp.Expr]) -> Callable[[AC], AC]:
"""Applies sympy expand operation to all equations in collection."""
def f(assignment_collection: AC) -> AC:
--
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