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| 1 | +#!/usr/bin/env python3 |
| 2 | +# Copyright lowRISC contributors (OpenTitan project). |
| 3 | +# Licensed under the Apache License, Version 2.0, see LICENSE for details. |
| 4 | +# SPDX-License-Identifier: Apache-2.0 |
| 5 | +r"""Checks the generated netlist for suspicious synthesis optimizations |
| 6 | +
|
| 7 | +Specifically, this script parses the netlist for suspicious patterns. These |
| 8 | +checks do *not* replace a final manual inspection of the netlist, but help to |
| 9 | +find problems early in the design! |
| 10 | +""" |
| 11 | + |
| 12 | +import sys |
| 13 | +import re |
| 14 | +import argparse |
| 15 | + |
| 16 | + |
| 17 | +def hr(char: str) -> None: |
| 18 | + print(char * 80) |
| 19 | + |
| 20 | + |
| 21 | +class Parser: |
| 22 | + # List of patterns we want to use for finding size_only constraints. |
| 23 | + size_only_patterns = [ |
| 24 | + "u_size_only", |
| 25 | + "u_size_only_xor", "u_size_only_xnor", "u_size_only_and", |
| 26 | + "u_size_only_mux", "u_size_only_flop", "u_size_only_buf", |
| 27 | + "u_size_only_clock_gate" |
| 28 | + ] |
| 29 | + |
| 30 | + # Regex to find ".lc_en_i, ( ... )" and capture the content |
| 31 | + pattern_lc_in = re.compile(r'\.lc_en_i \((.*?)\)') |
| 32 | + |
| 33 | + # Regex to find ".mubi_i, ( ... )" and capture the content |
| 34 | + pattern_mubi_in = re.compile(r'\.mubi_i \((.*?)\)') |
| 35 | + |
| 36 | + # Regex to find "assign mubi_o[*] = " const" |
| 37 | + pattern_mubi_const = re.compile(r'assign\s+([^=\s]*mubi_o[^=\s]*)\s*' |
| 38 | + f'=\s*(.*?)\'b[01]+;') |
| 39 | + |
| 40 | + # Regex to find "assign test*_o[*] = " const" |
| 41 | + pattern_test_const = re.compile(r'assign\s+(test_.*_o.*?)\s*=' |
| 42 | + r'\s*(.*?)\'b[01]+;') |
| 43 | + |
| 44 | + # tie low/high pattern |
| 45 | + pattern_tie_low_high = re.compile(r"\'b[01]") |
| 46 | + |
| 47 | + # pattern to find a module name |
| 48 | + pattern_module = re.compile(r'^\s*module\s+([a-zA-Z_][a-zA-Z0-9_]*)') |
| 49 | + |
| 50 | + # valid mubi4, mubi8, mubi12 patterns |
| 51 | + mubi_allowed_patterns = ["12'b100101101001", "12'b11010010110", |
| 52 | + "8'b1101001", "8'b10010110", |
| 53 | + "4'b110", "4'b1001"] |
| 54 | + |
| 55 | + # valid lc patterns |
| 56 | + lc_allowed_patterns = ["4'b101", "4'b1010"] |
| 57 | + |
| 58 | + # A count of how many instances we have seen of each of the size_only |
| 59 | + # patterns (ordered the same as size_only_patterns). |
| 60 | + size_only_count: list[int] = [0 for pat in size_only_patterns] |
| 61 | + |
| 62 | + # The name of the module (if known) |
| 63 | + module_name: str | None = None |
| 64 | + |
| 65 | + # Number of errors seen so far |
| 66 | + errors: int = 0 |
| 67 | + |
| 68 | + # A list of module names where errors have been found |
| 69 | + error_modules: set[str] = set() |
| 70 | + |
| 71 | + def describe_module(self) -> str: |
| 72 | + return ('unknown module' if self.module_name is None |
| 73 | + else f'module {self.module_name}') |
| 74 | + |
| 75 | + def on_error(self, |
| 76 | + linenum: int, line: str, |
| 77 | + desc: str, bad_match: str | None) -> None: |
| 78 | + print(f"Error: {desc} in {self.describe_module()}, line {linenum}:") |
| 79 | + print(f" Full line: {line.strip()}") |
| 80 | + if bad_match is not None: |
| 81 | + print(f" Content parsed: {bad_match}") |
| 82 | + |
| 83 | + hr('-') |
| 84 | + |
| 85 | + self.errors += 1 |
| 86 | + if self.module_name is not None: |
| 87 | + self.error_modules.add(self.module_name) |
| 88 | + |
| 89 | + def take_line(self, line_number: int, line: str) -> None: |
| 90 | + # Parse for module name: "module xxx(..." |
| 91 | + match_module = Parser.pattern_module.match(line) |
| 92 | + if match_module: |
| 93 | + self.module_name = match_module.group(1) |
| 94 | + |
| 95 | + # check for constant lc signals |
| 96 | + lc_match = Parser.pattern_lc_in.search(line) |
| 97 | + if lc_match: |
| 98 | + content = lc_match.group(1).strip() |
| 99 | + if Parser.pattern_tie_low_high.search(content): |
| 100 | + if content not in Parser.lc_allowed_patterns: |
| 101 | + self.on_error(line_number, line, |
| 102 | + 'invalid constant lc_en_i', content) |
| 103 | + |
| 104 | + # check for constant mubi_i signals |
| 105 | + mubi_i_match = Parser.pattern_mubi_in.search(line) |
| 106 | + if mubi_i_match: |
| 107 | + content = mubi_i_match.group(1).strip() |
| 108 | + if Parser.pattern_tie_low_high.search(content): |
| 109 | + if content not in Parser.mubi_allowed_patterns: |
| 110 | + self.on_error(line_number, line, |
| 111 | + 'invalid constant mubi_i', content) |
| 112 | + |
| 113 | + # check for constant mubi_o signals |
| 114 | + if Parser.pattern_mubi_const.search(line): |
| 115 | + self.on_error(line_number, line, 'tied low/high mubi bit', None) |
| 116 | + |
| 117 | + # check for constant test-outputs in prim_sdc_example |
| 118 | + if ((self.module_name == "prim_sdc_example" and |
| 119 | + Parser.pattern_test_const.search(line))): |
| 120 | + self.on_error(line_number, line, 'tied low/high test*_o*', None) |
| 121 | + |
| 122 | + # Count size_only instances |
| 123 | + for i, pattern in enumerate(Parser.size_only_patterns): |
| 124 | + if pattern in line: |
| 125 | + self.size_only_count[i] += 1 |
| 126 | + |
| 127 | + def report(self) -> None: |
| 128 | + hr('=') |
| 129 | + print("Final Summary:") |
| 130 | + hr('-') |
| 131 | + print("Found the following size_only instances:") |
| 132 | + hr('-') |
| 133 | + |
| 134 | + # Print the number of specific size_only matches that we have seen |
| 135 | + # (with a suffix from _xor, _xnor, _only_and, ...) |
| 136 | + specific_count = 0 |
| 137 | + for i, pattern in enumerate(Parser.size_only_patterns[1:], 1): |
| 138 | + print(f"{pattern:<30}{self.size_only_count[i]}") |
| 139 | + specific_count += self.size_only_count[i] |
| 140 | + |
| 141 | + # Each of those specific hits will also have matched u_size_only (the |
| 142 | + # first pattern). Subtracting specific_count from size_only_count[0] |
| 143 | + # gives the number of lines that are match u_size_only but don't match |
| 144 | + # one of the specific patterns. |
| 145 | + other_count = self.size_only_count[0] - specific_count |
| 146 | + print(f"{'others':<30}{other_count}") |
| 147 | + |
| 148 | + hr('-') |
| 149 | + |
| 150 | + # Since we know that every match for a specific case will also match |
| 151 | + # the first pattern, the number of lines that match equals |
| 152 | + # size_only_count[0] |
| 153 | + print(f"{'Total':<30}{self.size_only_count[0]}") |
| 154 | + hr('=') |
| 155 | + |
| 156 | + print(f"Found {self.errors} potential netlist problems " |
| 157 | + f"in {len(self.error_modules)} modules!") |
| 158 | + hr('=') |
| 159 | + |
| 160 | + |
| 161 | +def parse_expressions(filename): |
| 162 | + try: |
| 163 | + with open(filename, 'r') as file: |
| 164 | + lines = list(file) |
| 165 | + except FileNotFoundError: |
| 166 | + print(f"Error: The file '{filename}' was not found.") |
| 167 | + return 1 |
| 168 | + |
| 169 | + parser = Parser() |
| 170 | + for idx, line in enumerate(lines, 1): |
| 171 | + parser.take_line(idx, line) |
| 172 | + parser.report() |
| 173 | + |
| 174 | + return parser.errors |
| 175 | + |
| 176 | + |
| 177 | +if __name__ == "__main__": |
| 178 | + |
| 179 | + parser = argparse.ArgumentParser( |
| 180 | + description="Parses a synthesized netlist for suspicious constructs and counts all size_only " |
| 181 | + "instances.", |
| 182 | + epilog="Note: This script does not guarantee that there are no issues in the netlist (!)" |
| 183 | + ) |
| 184 | + |
| 185 | + parser.add_argument( |
| 186 | + "netlist_filename", |
| 187 | + type=str, |
| 188 | + help="The path to the netlist file (e.g., netlist.v) to be parsed." |
| 189 | + ) |
| 190 | + |
| 191 | + args = parser.parse_args() |
| 192 | + |
| 193 | + |
| 194 | + hr('=') |
| 195 | + print("DISCLAIMER:\n" |
| 196 | + "This script parses a synthesized netlist for suspicious constructs.\n" |
| 197 | + "It does not guarantee that there are no issues in the netlist(!)") |
| 198 | + hr('=') |
| 199 | + print('\n') |
| 200 | + |
| 201 | + if len(sys.argv) < 2: |
| 202 | + print("Usage: ./check-netlist.py <netlist_filename>") |
| 203 | + sys.exit(2) |
| 204 | + |
| 205 | + file_to_parse = sys.argv[1] |
| 206 | + errors = parse_expressions(file_to_parse) |
| 207 | + |
| 208 | + if (errors > 0): |
| 209 | + sys.exit(1) # Exits with 1 on error |
| 210 | + else: |
| 211 | + sys.exit(0) # Exits with 0 on success |
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