Storing shape & strides in constants, not reading from array

-> reading from arrays was slower with some compilers

transformations.py

@@ -3,10 +3,10 @@ from operator import attrgetter
 
 import sympy as sp
 from sympy.logic.boolalg import Boolean
-from sympy.tensor import IndexedBase
+from sympy.tensor import IndexedBase, Indexed
 
 from pystencils.field import Field, offsetComponentToDirectionString
-from pystencils.types import TypedSymbol, createType, PointerType, StructType, getBaseType
+from pystencils.types import TypedSymbol, createType, PointerType, StructType, getBaseType, createTypeFromString
 from pystencils.slicing import normalizeSlice
 import pystencils.astnodes as ast
 
@@ -219,6 +219,34 @@ def parseBasePointerInfo(basePointerSpecification, loopOrder, field):
     return result
 
 
+def substituteShapeAndStrideWithConstants(kernelFunctionAstNode):
+    fieldAccesses = kernelFunctionAstNode.atoms(Field.Access)
+    fields = {fa.field for fa in fieldAccesses}
+    fields = list(fields)
+    fields.sort(key=lambda f: f.name)
+
+    for field in fields:
+        if all(isinstance(e, Indexed) for e in field.shape):
+            newShape = []
+            shapeDtype = getBaseType(createTypeFromString(Field.SHAPE_DTYPE))
+            shapeDtype.const = False
+            for i, shape in enumerate(field.shape):
+                symbol = TypedSymbol("shapeConst_%s_%d" % (field.name, i), shapeDtype)
+                kernelFunctionAstNode.body.insertFront(ast.SympyAssignment(symbol, shape))
+                newShape.append(symbol)
+            field.shape = tuple(newShape)
+
+        if all(isinstance(e, Indexed) for e in field.strides):
+            newStrides = []
+            strideDtype = getBaseType(createTypeFromString(Field.STRIDE_DTYPE))
+            strideDtype.const = False
+            for i, stride in enumerate(field.strides):
+                symbol = TypedSymbol("strideConst_%s_%d" % (field.name, i), strideDtype)
+                kernelFunctionAstNode.body.insertFront(ast.SympyAssignment(symbol, stride))
+                newStrides.append(symbol)
+            field.strides = tuple(newStrides)
+
+
 def resolveFieldAccesses(astNode, readOnlyFieldNames=set(), fieldToBasePointerInfo={}, fieldToFixedCoordinates={}):
     """
     Substitutes :class:`pystencils.field.Field.Access` nodes by array indexing
@@ -231,6 +259,7 @@ def resolveFieldAccesses(astNode, readOnlyFieldNames=set(), fieldToBasePointerIn
                                     counters to index the field these symbols are used as coordinates
     :return: transformed AST
     """
+    substituteShapeAndStrideWithConstants(astNode)
 
     fieldToBasePointerInfo = OrderedDict(sorted(fieldToBasePointerInfo.items(), key=lambda pair: pair[0]))
     fieldToFixedCoordinates = OrderedDict(sorted(fieldToFixedCoordinates.items(), key=lambda pair: pair[0]))