用python实现网表分模块统计面积

虽然dc也有report_area -hier命令来报告各级模块的面积，本python方案看似有点造轮子，但还是有一定的便利性。一、不受网表类型的限制，综合网表、DFT网表、APR都可以。二、可以过滤面积小于指定值的小模块，比如工具自动插入的ICG模块。三、还可以根据面积占比做排序，方便分析面积的瓶颈。

一、读入网表

下面先读入网表，并分模块识别每个模块内部的stdcell和子模块。这部分与《用python实现分模块按cell类型统计cell个数并降序排列》的方法相同，所以这里直接导入netlistparser.py。

import netlistparser as nlparser
import sys


vlog_netlist_file = sys.argv[2]
modules=nlparser.read_vlog_netlist(vlog_netlist_file)

这样网表就读到了内部python字典里，结构如下：

{
"moduleA": {
"module_name": "moduleA",
"insts": {
"u_AND2_01":"AND2X1",
"u_AND2_02": "AND2X1",
"u_OR2_01":"OR2X1",
"u_INV_01":"INVX1"
}
},
"moduleB": {
    "module_name": "moduleB",
    "insts": {
        "u_AND2_01": "AND2X1",
        "u_AND2_02": "AND2X1",
        "u_OR2_01": "OR2X1",
        "u_INV_01": "INVX1"        
    }
},
}

二、读入lib库

stdcell的面积信息存储在fab提供的lib文件里，所以我们需要从lib里读到每种cell的面积，方法如下：

# libparser.py
import sys
import re
import json




def read_library(file_name):
    cells = {}
    
    lib_lines = open(file_name, 'r').readlines()


    cell_start = 0    
    pin_start = 0


    total_lines = len(lib_lines)
    print('')
    
    for i in range(total_lines):
        line = lib_lines[i]
        print('33[1F {}%'.format(round(100 * i / total_lines)))
        
cell_s_m=re.search(r'cells*((w+))s+{',line)
area_m=re.search(r'sareas+:s+(S+)s*;',line)
        pin_s_m  = re.search(r'spin((w+))s+{', line)
        dir_m    = re.search(r'sdirections+:s+(w+)', line)
        func_m   = re.search(r'sfunctions+:s+"(.*)"', line)
        end_m    = re.search(r'}', line)


        if cell_s_m:
            cell_start = 1
            cell = {}
            cell_name = cell_s_m.group(1)
            cell['cell_name'] = cell_name
            pins = []
            cell['pins'] = pins
            cells[cell_name] = cell


        if cell_start and area_m:
            area = area_m.group(1)
            cell['area'] = round(float(area), 4)
        
        if cell_start and pin_s_m:
            pin_start = 1
            pin = {}
            pin_name = pin_s_m.group(1)
            pin['pin_name'] = pin_name


        if cell_start and dir_m:
            pin_dir = dir_m.group(1)
            pin['pin_dir'] = pin_dir


        if cell_start and func_m:
            pin_func = func_m.group(1)
            pin['pin_func'] = pin_func


        if cell_start and pin_start and end_m:
            pin_start = 0
            pins.append(pin)
            
    return cells




def get_cell_area(cells, cell_name):
    if cell_name in cells:
        return cells[cell_name]['area']
    else:
        return 0




def is_libcell(cells, cell_name):
    if cell_name in cells:
        return True
    else:
        return False




def write_lib_info(lib_info, file_name):
    f = open(file_name, 'w')
    f.write(json.dumps(lib_info, indent=4))
    f.close()

其中，read_library()函数实现了用正则读取lib文件里的cell名字、area、pin、pin方向、function等信息。今天只需要用到cell名字和面积。其它信息是为了后续扩展其它功能做准备。

get_cell_area()提供了读取指定cell面积的接口。is_libcell()实现了判断是libcell还是一般的设计上的子模块。

write_lib_info()可以将lib库的字典写到json文件里，方便调试。

接下来，用这个libparser读入lib库：

import libparser
import sys


lib_file = sys.argv[1]
lib_info=libparser.read_library(lib_file)

三、面积递归统计

我们从top design开始，当遇到stdcell中的cell则累加，当遇到子模块则递归。直到子模块不再含有其它子模块（仅由stdcell组成）时，则返回。

area_info = {}
def report_area(modules, lib_info, module_name):
    global area_info
    area = 0
    
    insts = modules[module_name]['insts']
    for inst in insts:
        cell_inst = inst
        cell_type = insts[inst]
        if cell_type in area_info:
            area = area + area_info[cell_type]
        elif libparser.is_libcell(lib_info, cell_type):
            area = area + libparser.get_cell_area(lib_info, cell_type)
        else:
#递归
report_area(modules,lib_info,cell_type)
            area = area + area_info[cell_type]
    
area_info[module_name]=area

四、打印面积

打印的同时，可以做一些过滤或者排序。

for module in area_info:
        if not re.search(r'CLOCK_GATE', module):
            print(module, round(area_info[module], 4))

效果如下：