fish-shell/build_tools/find_weak_odrs.py
Mahmoud Al-Qudsi 86a442fb62 Make find_weak_odrs work with Python 3.6
`text` is an alias for `universal_newlines` but wasn't introduced until
Python 3.7
2021-10-04 19:45:36 -05:00

64 lines
2.1 KiB
Python
Executable File

#!/usr/bin/env python3
# Finds potential ODR violations due to weak symbols.
# For example, if you have two different structs with the same name in different files,
# their inline constructors may collide.
# This works only on Linux. It is designed to be run from the cmake build directory.
# clang seems more willing to emit non-inlined ctors. Of course perform a Debug build.
import re
import subprocess
output = subprocess.check_output(
"nm --radix=d -g --demangle -l --print-size CMakeFiles/fishlib.dir/src/*.o",
shell=True,
universal_newlines=True,
)
files_by_name = {} # Symbol to set of paths
sizes_by_name = {} # Symbol to set of int sizes
for line in output.split("\n"):
# Keep only weak symbols with default values (e.g. emitted inline functions).
# Example line: "0000000000000000 0000000000000107 W symbol_name"
# First number is offset, second is size.
# Note this is decimal because of radix=d.
m = re.match(r"\d+ (\d+) W (.*)\t(.*)", line)
if not m:
continue
size, name, filename = m.groups()
files_by_name.setdefault(name, set()).add(filename)
sizes_by_name.setdefault(name, set()).add(int(size))
odr_violations = 0
for name, sizes in sizes_by_name.items():
if len(sizes) == 1:
continue
files = files_by_name[name]
# Ignore symbols that only appear in one file.
# These are typically headers - unclear why they get different sizes but it appears benign.
if len(files) == 1:
continue
# Multiple sizes for this symbol name.
odr_violations += 1
print("Multiple sizes for symbol: " + name)
print("\t%s" % ", ".join([str(x) for x in sizes]))
print("\tFound in files:")
for filename in files:
print("\t\t%s" % filename)
if odr_violations == 0:
print("No ODR violations found, hooray\n")
# Show potential weak symbols.
suspicious_odrs = 0
for (name, files) in files_by_name.items():
if len(files) != 1:
continue
(filename,) = files
if ".cpp" in filename:
if suspicious_odrs == 0:
print("Some suspicious singles:")
suspicious_odrs += 1
print("\t%s" % name)
print("\t\tIn file %s" % filename)