def replace_class_references(ast, classrefs):
"""
This function performs rewrites for the HLS hardware design.
Replace references to static class information with juniper_get_class_reference, a hardcoded syscall
back to the host which fetches a juniper_ref of the class metadata.
"""
def recurse(node):
for c in node.children():
recurse(c[1])
if isinstance(node, c_ast.ID):
if node.name in classrefs.all:
if not node.name in classrefs.referenced:
classrefs.referenced[node.name] = len(classrefs.referenced) + 1
fcall = make_func_call_node("juniper_get_class_reference", ["1", str(classrefs.referenced[node.name])])
replace_node(node, fcall)
recurse(ast)
add_parent_links(ast)
def rewrite_RAM_structure_dereferences(ast):
"""
The replacement Jamaica headers use RAM_NAME as a global pointer to the external bus interface.
Unfortunately, JamaicaBuilder assumes that the type of this pointer is a complex
union-of-structs-of-arrays. This rewrites such accesses to use a set of memory access functions
declared in fpgaporting.h that allow a more HLS-friendly representation of RAM.
We are looking for structures like the following:
ArrayRef:
StructRef: .
ArrayRef:
ID: __juniper_ram_master
<Anything else>
ID: f
Constant: int, 2
"""
def rewrite_structref(node):
"""
Called by recurse to check a StructRef node for if rewrites are necessary, and if so, make them.
"""
deref_type = node.field.name # What was dereferenced ('i', 's', 'c', 'r', etc.)
# When a subword type, there may be a higher level arrayref :- __juniper_ram_master[x].s[4]
# Save the '4' ast in top_array_deref
top_array_deref = None
if isinstance(node.parent, c_ast.ArrayRef) and not node == node.parent.subscript:
top_array_deref = node.parent.subscript
nodetoreplace = node.parent
else:
nodetoreplace = node
arf = node.name
if isinstance(nodetoreplace.parent, c_ast.Assignment) and nodetoreplace.parent.op == "=" and nodetoreplace.parent.lvalue == nodetoreplace:
callname = RAM_SET_NAME
callargs = [arf.subscript, top_array_deref, nodetoreplace.parent.rvalue]
nodetoreplace = nodetoreplace.parent # The top level Assignment
else:
callname = RAM_GET_NAME
callargs = [arf.subscript, top_array_deref]
callname = callname + str(deref_type)
replacementnode = make_func_call_node(callname, callargs)
replace_node(nodetoreplace, replacementnode)
def recurse(node):
"""
Recurse depth-first through the provided AST down to the leaf nodes.
Then, whilst popping off the stack, any StructRef nodes are passed to rewrite_structref
If changes are made, returns True
"""
changemade = False
for c in node.children():
if recurse(c[1]):
changemade = True
if isinstance(node, c_ast.StructRef):
if node.type == "." and isinstance(node.name, c_ast.ArrayRef) and node.name.name.name == RAM_NAME:
rewrite_structref(node)
changemade = True
return changemade
while recurse(ast):
# After moving nodes we need to correct the parent links.
# TODO: Potential optimisation to fix the links only as they are moved, but this isn't too slow
add_parent_links(ast)
