5. Data model

The SiliconCompiler Schema is a data structure that stores all configurations and metrics gathered during the compilation process. Each schema entry (“parameter”) is a self contained leaf cell with a required set of standardized key/value pairs (“fields”). The example below shows the definition of one of the parameters named ‘design’.

scparam(cfg,['design'],
        sctype='str',
        scope='global',
        require='all',
        shorthelp="Design top module name",
        switch="-design <str>",
        example=["cli: -design hello_world",
                "api: chip.set('design', 'hello_world')"],
        schelp="""Name of the top level module or library. Required for all
        chip objects.""")

The table below summarizes mandatory fields used in all parameter definitions.

Field	Description	Values
type	Parameter type	file, dir, str, float, bool, int, [], (a,b)
defvalue	Default schema value	Type dependent
shorthelp	Short single line help string.	String
help	Multi-line documentation string	String
example	Usage examples for CLI ad API	String
lock	Enable/disable for set()/add() methods	True / False
require	Flow based use requirements	String
switch	Mapping of parameter to a CLI switch	String

The file type parameters have the additional required fields show in the table below:

Field	Description	Legal Values
author	File author	String
date	File date stamp	String
signature	Author signature key	String
filehash	File hash value	String
hashalgo	Hashing algorithm used	sha256,md5,…
copy	Whether to copy files into build directory	True / False

Accessing schema parameters is done using the set(), get(), and add() Python methods. The following shows how to create a chip object and manipulate a schema parameter in Python.

import siliconcompiler
chip = siliconcompiler.Chip('hello_world')
chip.set('input', 'verilog', 'hello_world.v')
print(chip.get('input', 'verilog'))

Reading and writing the schema to and from disk is handled by the read_manifest() and write_manifest() Python API methods. Supported export file formats include TCL, JSON, and YAML. By default, only non-empty values are written to disk.

import siliconcompiler
chip = siliconcompiler.Chip('hello_world')
chip.write_manifest('hello_world.json')

The JSON structure below shows the ‘design’ parameter exported by the write_manifest() method.

"design": {
    "defvalue": null,
    "example": [
        "cli: -design hello_world",
        "api: chip.set('design', 'hello_world')"
    ],
    "help": "Name of the top level module or library. Required for all\nchip objects.",
    "lock": "false",
    "notes": null,
    "require": "all",
    "scope": "global",
    "shorthelp": "Design top module name",
    "signature": null,
    "switch": "-design <str>",
    "type": "str",
    "value": "hello_world"
},

To handle complex scenarios required by advanced PDKs, the Schema supports dynamic nested dictionaries. A ‘default’ keyword is used to define the dictionary structure during object creation. Populating the object dictionary with actual keys is done by the user during compilation setup. The example below illustrates how ‘default’ is used as a placeholder for the timing model filetype and corner. These dynamic dictionaries makes it easy to set up an arbitrary number of libraries and corners in a PDK using Python loops.

filetype = 'default
corner = 'default'
# ...
scparam(cfg,['model', 'timing', filetype, corner],
         sctype='[file]',
         scope='global',
         shorthelp=f"Model: Timing",
         switch=f"-model_timing 'filetype corner <file>'",
         example=[
             f"cli: -model_timing 'nldm-libgz ss ss.lib.gz'",
             f"api: chip.set('model','timing','nldm-ldb','ss','ss.ldb')"],
         schelp=f"""
         Filepaths to static timing models specified on a per filetype and
         per corner basis.  Examples of filetypes include: nldm, nldm-ldb,
         nldm-libgz, ccs, ccs-libgz, ccs-ldb, scm, scm-libgz, scm-ldb,
         aocv, aocv-libgz, aocv-ldb.""")

The SiliconCompiler Schema is roughly divided into the following major sub-groups:

Group	Parameters	Description
option	47	Compilation options
tool	24	Individual tool settings
flowgraph	8	Execution flow definition
pdk	46	PDK related settings
asic	45	ASIC related settings
fpga	5	FPGA related settings
constraint	7	Advanced timing analysis settings
model	7	Models/abstractions of design
metric	40	Metric tracking
record	15	Compilation history tracking
package	28	Packaging manifest
datasheet	36	Design interface specifications
units	9	Global units
total	317

Refer to the Schema and Python API sections of the reference manual for more information. Another good resource is the single file Schema source code.