llvm-project/llvm/utils/extract_symbols.py
Tomas Matheson 3884f07a55 [extract_symbols.py] Export unique symbols
As described in a comment on D140637, PluginInlineOrderTest.NoInlineFoo
will fail with:

InlineOrderPlugin.so: undefined symbol: _ZN4llvm13AllAnalysesOnINS_6ModuleEE6SetKeyE

The symbol is unique in libLLVMCore and ends up local in AnalysisTests.
Fix this by exporting all unique symbols found in libraries.

AnalysisTests.symbols change in line count: 12464 -> 12499

Differential Revision: https://reviews.llvm.org/D146731
2023-03-24 16:37:43 +00:00

535 lines
21 KiB
Python
Executable File

#!/usr/bin/env python
"""A tool for extracting a list of symbols to export
When exporting symbols from a dll or exe we either need to mark the symbols in
the source code as __declspec(dllexport) or supply a list of symbols to the
linker. This program automates the latter by inspecting the symbol tables of a
list of link inputs and deciding which of those symbols need to be exported.
We can't just export all the defined symbols, as there's a limit of 65535
exported symbols and in clang we go way over that, particularly in a debug
build. Therefore a large part of the work is pruning symbols either which can't
be imported, or which we think are things that have definitions in public header
files (i.e. template instantiations) and we would get defined in the thing
importing these symbols anyway.
"""
from __future__ import print_function
import sys
import re
import os
import subprocess
import multiprocessing
import argparse
# Define functions which extract a list of pairs of (symbols, is_def) from a
# library using several different tools. We use subprocess.Popen and yield a
# symbol at a time instead of using subprocess.check_output and returning a list
# as, especially on Windows, waiting for the entire output to be ready can take
# a significant amount of time.
def dumpbin_get_symbols(lib):
process = subprocess.Popen(['dumpbin','/symbols',lib], bufsize=1,
stdout=subprocess.PIPE, stdin=subprocess.PIPE,
universal_newlines=True)
process.stdin.close()
for line in process.stdout:
# Look for external symbols
match = re.match("^.+(SECT|UNDEF).+External\s+\|\s+(\S+).*$", line)
if match:
yield (match.group(2), match.group(1) != "UNDEF")
process.wait()
def nm_get_symbols(lib):
# -P means the output is in portable format, and -g means we only get global
# symbols.
cmd = ['nm','-P','-g']
if sys.platform.startswith('aix'):
cmd += ['-Xany','-C','-p']
process = subprocess.Popen(cmd+[lib], bufsize=1,
stdout=subprocess.PIPE, stdin=subprocess.PIPE,
universal_newlines=True)
process.stdin.close()
for line in process.stdout:
# Look for external symbols that are defined in some section
# The POSIX format is:
# name type value size
# The -P flag displays the size field for symbols only when applicable,
# so the last field is optional. There's no space after the value field,
# but \s+ match newline also, so \s+\S* will match the optional size field.
match = re.match("^(\S+)\s+[BDGRSTuVW]\s+\S+\s+\S*$", line)
if match:
yield (match.group(1), True)
# Look for undefined symbols, which have type U and may or may not
# (depending on which nm is being used) have value and size.
match = re.match("^(\S+)\s+U\s+(\S+\s+\S*)?$", line)
if match:
yield (match.group(1), False)
process.wait()
def readobj_get_symbols(lib):
process = subprocess.Popen(['llvm-readobj','--symbols',lib], bufsize=1,
stdout=subprocess.PIPE, stdin=subprocess.PIPE,
universal_newlines=True)
process.stdin.close()
for line in process.stdout:
# When looking through the output of llvm-readobj we expect to see Name,
# Section, then StorageClass, so record Name and Section when we see
# them and decide if this is an external symbol when we see
# StorageClass.
match = re.search('Name: (\S+)', line)
if match:
name = match.group(1)
match = re.search('Section: (\S+)', line)
if match:
section = match.group(1)
match = re.search('StorageClass: (\S+)', line)
if match:
storageclass = match.group(1)
if section != 'IMAGE_SYM_ABSOLUTE' and \
storageclass == 'External':
yield (name, section != 'IMAGE_SYM_UNDEFINED')
process.wait()
# Define functions which determine if the target is 32-bit Windows (as that's
# where calling convention name decoration happens).
def dumpbin_is_32bit_windows(lib):
# dumpbin /headers can output a huge amount of data (>100MB in a debug
# build) so we read only up to the 'machine' line then close the output.
process = subprocess.Popen(['dumpbin','/headers',lib], bufsize=1,
stdout=subprocess.PIPE, stdin=subprocess.PIPE,
universal_newlines=True)
process.stdin.close()
retval = False
for line in process.stdout:
match = re.match('.+machine \((\S+)\)', line)
if match:
retval = (match.group(1) == 'x86')
break
process.stdout.close()
process.wait()
return retval
def objdump_is_32bit_windows(lib):
output = subprocess.check_output(['objdump','-f',lib],
universal_newlines=True)
for line in output.splitlines():
match = re.match('.+file format (\S+)', line)
if match:
return (match.group(1) == 'pe-i386')
return False
def readobj_is_32bit_windows(lib):
output = subprocess.check_output(['llvm-readobj','--file-header',lib],
universal_newlines=True)
for line in output.splitlines():
match = re.match('Format: (\S+)', line)
if match:
return (match.group(1) == 'COFF-i386')
return False
# On AIX, there isn't an easy way to detect 32-bit windows objects with the system toolchain,
# so just assume false.
def aix_is_32bit_windows(lib):
return False
# MSVC mangles names to ?<identifier_mangling>@<type_mangling>. By examining the
# identifier/type mangling we can decide which symbols could possibly be
# required and which we can discard.
def should_keep_microsoft_symbol(symbol, calling_convention_decoration):
# Keep unmangled (i.e. extern "C") names
if not '?' in symbol:
if calling_convention_decoration:
# Remove calling convention decoration from names
match = re.match('[_@]([^@]+)', symbol)
if match:
symbol = match.group(1)
# Discard floating point/SIMD constants.
if symbol.startswith(("__xmm@", "__ymm@", "__real@")):
return None
return symbol
# Deleting destructors start with ?_G or ?_E and can be discarded because
# link.exe gives you a warning telling you they can't be exported if you
# don't
elif symbol.startswith('??_G') or symbol.startswith('??_E'):
return None
# An anonymous namespace is mangled as ?A(maybe hex number)@. Any symbol
# that mentions an anonymous namespace can be discarded, as the anonymous
# namespace doesn't exist outside of that translation unit.
elif re.search('\?A(0x\w+)?@', symbol):
return None
# Skip X86GenMnemonicTables functions, they are not exposed from llvm/include/.
elif re.match('\?is[A-Z0-9]*@X86@llvm', symbol):
return None
# Keep mangled llvm:: and clang:: function symbols. How we detect these is a
# bit of a mess and imprecise, but that avoids having to completely demangle
# the symbol name. The outermost namespace is at the end of the identifier
# mangling, and the identifier mangling is followed by the type mangling, so
# we look for (llvm|clang)@@ followed by something that looks like a
# function type mangling. To spot a function type we use (this is derived
# from clang/lib/AST/MicrosoftMangle.cpp):
# <function-type> ::= <function-class> <this-cvr-qualifiers>
# <calling-convention> <return-type>
# <argument-list> <throw-spec>
# <function-class> ::= [A-Z]
# <this-cvr-qualifiers> ::= [A-Z0-9_]*
# <calling-convention> ::= [A-JQ]
# <return-type> ::= .+
# <argument-list> ::= X (void)
# ::= .+@ (list of types)
# ::= .*Z (list of types, varargs)
# <throw-spec> ::= exceptions are not allowed
elif re.search('(llvm|clang)@@[A-Z][A-Z0-9_]*[A-JQ].+(X|.+@|.*Z)$', symbol):
return symbol
return None
# Itanium manglings are of the form _Z<identifier_mangling><type_mangling>. We
# demangle the identifier mangling to identify symbols that can be safely
# discarded.
def should_keep_itanium_symbol(symbol, calling_convention_decoration):
# Start by removing any calling convention decoration (which we expect to
# see on all symbols, even mangled C++ symbols)
if calling_convention_decoration and symbol.startswith('_'):
symbol = symbol[1:]
# Keep unmangled names
if not symbol.startswith('_') and not symbol.startswith('.'):
return symbol
# Discard manglings that aren't nested names
match = re.match('_Z(T[VTIS])?(N.+)', symbol)
if not match:
return None
# Demangle the name. If the name is too complex then we don't need to keep
# it, but it the demangling fails then keep the symbol just in case.
try:
names, _ = parse_itanium_nested_name(match.group(2))
except TooComplexName:
return None
if not names:
return symbol
# Keep llvm:: and clang:: names
elif names[0][0] == '4llvm' or names[0][0] == '5clang':
return symbol
# Discard everything else
else:
return None
# Certain kinds of complex manglings we assume cannot be part of a public
# interface, and we handle them by raising an exception.
class TooComplexName(Exception):
pass
# Parse an itanium mangled name from the start of a string and return a
# (name, rest of string) pair.
def parse_itanium_name(arg):
# Check for a normal name
match = re.match('(\d+)(.+)', arg)
if match:
n = int(match.group(1))
name = match.group(1)+match.group(2)[:n]
rest = match.group(2)[n:]
return name, rest
# Check for constructor/destructor names
match = re.match('([CD][123])(.+)', arg)
if match:
return match.group(1), match.group(2)
# Assume that a sequence of characters that doesn't end a nesting is an
# operator (this is very imprecise, but appears to be good enough)
match = re.match('([^E]+)(.+)', arg)
if match:
return match.group(1), match.group(2)
# Anything else: we can't handle it
return None, arg
# Parse an itanium mangled template argument list from the start of a string
# and throw it away, returning the rest of the string.
def skip_itanium_template(arg):
# A template argument list starts with I
assert arg.startswith('I'), arg
tmp = arg[1:]
while tmp:
# Check for names
match = re.match('(\d+)(.+)', tmp)
if match:
n = int(match.group(1))
tmp = match.group(2)[n:]
continue
# Check for substitutions
match = re.match('S[A-Z0-9]*_(.+)', tmp)
if match:
tmp = match.group(1)
# Start of a template
elif tmp.startswith('I'):
tmp = skip_itanium_template(tmp)
# Start of a nested name
elif tmp.startswith('N'):
_, tmp = parse_itanium_nested_name(tmp)
# Start of an expression: assume that it's too complicated
elif tmp.startswith('L') or tmp.startswith('X'):
raise TooComplexName
# End of the template
elif tmp.startswith('E'):
return tmp[1:]
# Something else: probably a type, skip it
else:
tmp = tmp[1:]
return None
# Parse an itanium mangled nested name and transform it into a list of pairs of
# (name, is_template), returning (list, rest of string).
def parse_itanium_nested_name(arg):
# A nested name starts with N
assert arg.startswith('N'), arg
ret = []
# Skip past the N, and possibly a substitution
match = re.match('NS[A-Z0-9]*_(.+)', arg)
if match:
tmp = match.group(1)
else:
tmp = arg[1:]
# Skip past CV-qualifiers and ref qualifiers
match = re.match('[rVKRO]*(.+)', tmp);
if match:
tmp = match.group(1)
# Repeatedly parse names from the string until we reach the end of the
# nested name
while tmp:
# An E ends the nested name
if tmp.startswith('E'):
return ret, tmp[1:]
# Parse a name
name_part, tmp = parse_itanium_name(tmp)
if not name_part:
# If we failed then we don't know how to demangle this
return None, None
is_template = False
# If this name is a template record that, then skip the template
# arguments
if tmp.startswith('I'):
tmp = skip_itanium_template(tmp)
is_template = True
# Add the name to the list
ret.append((name_part, is_template))
# If we get here then something went wrong
return None, None
# Parse a microsoft mangled symbol and return a list of pairs of
# (name, is_template). This is very rudimentary and does just enough
# in order to determine if the first or second component is a template.
def parse_microsoft_mangling(arg):
# If the name doesn't start with ? this isn't a mangled name
if not arg.startswith('?'):
return [(arg, False)]
arg = arg[1:]
components = []
while len(arg) > 0:
# If we see an empty component we've reached the end
if arg.startswith('@'):
return components
# Check for a simple name
match = re.match('(\w+)@(.+)', arg)
if match:
components.append((match.group(1), False))
arg = match.group(2)
continue
# Check for a special function name
match = re.match('(\?_?\w)(.+)', arg)
if match:
components.append((match.group(1), False))
arg = match.group(2)
continue
# Check for a template name
match = re.match('\?\$(\w+)@[^@]+@(.+)', arg)
if match:
components.append((match.group(1), True))
arg = match.group(2)
continue
# Some other kind of name that we can't handle
components.append((arg, False))
return components
return components
def extract_symbols(arg):
get_symbols, should_keep_symbol, calling_convention_decoration, lib = arg
symbol_defs = dict()
symbol_refs = set()
for (symbol, is_def) in get_symbols(lib):
symbol = should_keep_symbol(symbol, calling_convention_decoration)
if symbol:
if is_def:
symbol_defs[symbol] = 1 + symbol_defs.setdefault(symbol,0)
else:
symbol_refs.add(symbol)
return (symbol_defs, symbol_refs)
def get_template_name(sym, mangling):
# Parse the mangling into a list of (name, is_template)
try:
if mangling == 'microsoft':
names = parse_microsoft_mangling(sym)
else:
match = re.match('_Z(T[VTIS])?(N.+)', sym)
if match:
names, _ = parse_itanium_nested_name(match.group(2))
else:
names = None
except TooComplexName:
return None
if not names:
return None
# If any component is a template then return it
for name, is_template in names:
if is_template:
return name
# Not a template
return None
if __name__ == '__main__':
tool_exes = ['dumpbin','nm','objdump','llvm-readobj']
parser = argparse.ArgumentParser(
description='Extract symbols to export from libraries')
parser.add_argument('--mangling', choices=['itanium','microsoft'],
required=True, help='expected symbol mangling scheme')
parser.add_argument('--tools', choices=tool_exes, nargs='*',
help='tools to use to extract symbols and determine the'
' target')
parser.add_argument('libs', metavar='lib', type=str, nargs='+',
help='libraries to extract symbols from')
parser.add_argument('-o', metavar='file', type=str, help='output to file')
args = parser.parse_args()
# Determine the function to use to get the list of symbols from the inputs,
# and the function to use to determine if the target is 32-bit windows.
tools = { 'dumpbin' : (dumpbin_get_symbols, dumpbin_is_32bit_windows),
'nm' : (nm_get_symbols, None),
'objdump' : (None, objdump_is_32bit_windows),
'llvm-readobj' : (readobj_get_symbols, readobj_is_32bit_windows) }
get_symbols = None
is_32bit_windows = aix_is_32bit_windows if sys.platform.startswith('aix') else None
# If we have a tools argument then use that for the list of tools to check
if args.tools:
tool_exes = args.tools
# Find a tool to use by trying each in turn until we find one that exists
# (subprocess.call will throw OSError when the program does not exist)
get_symbols = None
for exe in tool_exes:
try:
# Close std streams as we don't want any output and we don't
# want the process to wait for something on stdin.
p = subprocess.Popen([exe], stdout=subprocess.PIPE,
stderr=subprocess.PIPE,
stdin=subprocess.PIPE,
universal_newlines=True)
p.stdout.close()
p.stderr.close()
p.stdin.close()
p.wait()
# Keep going until we have a tool to use for both get_symbols and
# is_32bit_windows
if not get_symbols:
get_symbols = tools[exe][0]
if not is_32bit_windows:
is_32bit_windows = tools[exe][1]
if get_symbols and is_32bit_windows:
break
except OSError:
continue
if not get_symbols:
print("Couldn't find a program to read symbols with", file=sys.stderr)
exit(1)
if not is_32bit_windows:
print("Couldn't find a program to determining the target", file=sys.stderr)
exit(1)
# How we determine which symbols to keep and which to discard depends on
# the mangling scheme
if args.mangling == 'microsoft':
should_keep_symbol = should_keep_microsoft_symbol
else:
should_keep_symbol = should_keep_itanium_symbol
# Get the list of libraries to extract symbols from
libs = list()
for lib in args.libs:
# When invoked by cmake the arguments are the cmake target names of the
# libraries, so we need to add .lib/.a to the end and maybe lib to the
# start to get the filename. Also allow objects.
suffixes = ['.lib','.a','.obj','.o']
if not any([lib.endswith(s) for s in suffixes]):
for s in suffixes:
if os.path.exists(lib+s):
lib = lib+s
break
if os.path.exists('lib'+lib+s):
lib = 'lib'+lib+s
break
if not any([lib.endswith(s) for s in suffixes]):
print("Don't know what to do with argument "+lib, file=sys.stderr)
exit(1)
libs.append(lib)
# Check if calling convention decoration is used by inspecting the first
# library in the list
calling_convention_decoration = is_32bit_windows(libs[0])
# Extract symbols from libraries in parallel. This is a huge time saver when
# doing a debug build, as there are hundreds of thousands of symbols in each
# library.
pool = multiprocessing.Pool()
try:
# Only one argument can be passed to the mapping function, and we can't
# use a lambda or local function definition as that doesn't work on
# windows, so create a list of tuples which duplicates the arguments
# that are the same in all calls.
vals = [(get_symbols, should_keep_symbol, calling_convention_decoration, x) for x in libs]
# Do an async map then wait for the result to make sure that
# KeyboardInterrupt gets caught correctly (see
# http://bugs.python.org/issue8296)
result = pool.map_async(extract_symbols, vals)
pool.close()
libs_symbols = result.get(3600)
except KeyboardInterrupt:
# On Ctrl-C terminate everything and exit
pool.terminate()
pool.join()
exit(1)
# Merge everything into a single dict
symbol_defs = dict()
symbol_refs = set()
for (this_lib_defs, this_lib_refs) in libs_symbols:
for k,v in list(this_lib_defs.items()):
symbol_defs[k] = v + symbol_defs.setdefault(k,0)
for sym in list(this_lib_refs):
symbol_refs.add(sym)
# Find which template instantiations are referenced at least once.
template_instantiation_refs = set()
for sym in list(symbol_refs):
template = get_template_name(sym, args.mangling)
if template:
template_instantiation_refs.add(template)
# Print symbols which both:
# * Appear in exactly one input, as symbols defined in multiple
# objects/libraries are assumed to have public definitions.
# * Are not a template instantiation that isn't referenced anywhere. This
# is because we need to export any explicitly instantiated templates,
# and we expect those to be referenced in some object.
if args.o:
outfile = open(args.o,'w')
else:
outfile = sys.stdout
for k,v in list(symbol_defs.items()):
template = get_template_name(k, args.mangling)
if v == 1 and (not template or template in template_instantiation_refs):
print(k, file=outfile)