CbC/CbC_llvm: llvm/utils/extract_symbols.py comparison

comparison llvm/utils/extract_symbols.py @ 150:1d019706d866

LLVM10

author	anatofuz
date	Thu, 13 Feb 2020 15:10:13 +0900
parents
children	0572611fdcc8

comparison

equal deleted inserted replaced

-:c2174574ed3a
+:1d019706d866
+#!/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 symbols 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 that are defined in some section
+match = re.match("^.+SECT.+External\s+\|\s+(\S+).*$", line)
+if match:
+yield match.group(1)
+process.wait()
+def nm_get_symbols(lib):
+process = subprocess.Popen(['nm','-P',lib], bufsize=1,
+stdout=subprocess.PIPE, stdin=subprocess.PIPE,
+universal_newlines=True)
+process.stdin.close()
+for line in process.stdout:
+# Look for external symbols that are defined in some section
+match = re.match("^(\S+)\s+[BDGRSTVW]\s+\S+\s+\S+$", line)
+if match:
+yield match.group(1)
+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 a defined 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 \
+section != 'IMAGE_SYM_UNDEFINED' and \
+storageclass == 'External':
+yield name
+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:
+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-headers',lib],
+universal_newlines=True)
+for line in output:
+match = re.match('Format: (\S+)', line)
+if match:
+return (match.group(1) == 'COFF-i386')
+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:
+return match.group(1)
+return symbol
+# Function template instantiations start with ?$; keep the instantiations of
+# clang::Type::getAs, as some of them are explipict specializations that are
+# defined in clang's lib/AST/Type.cpp; discard the rest as it's assumed that
+# the definition is public
+elif re.match('\?\?\$getAs@.+@Type@clang@@', symbol):
+return symbol
+elif symbol.startswith('??$'):
+return None
+# 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
+# Constructors (?0) and destructors (?1) of templates (?$) are assumed to be
+# defined in headers and not required to be kept
+elif symbol.startswith('??0?$') or symbol.startswith('??1?$'):
+return None
+# An anonymous namespace is mangled as ?A(maybe hex number)@. Any symbol
+# that mentions an anonymous namespace can be discarded, as the anonymous
+# namespace doesn't exist outside of that translation unit.
+elif re.search('\?A(0x\w+)?@', symbol):
+return None
+# Keep mangled llvm:: and clang:: function symbols. How we detect these is a
+# bit of a mess and imprecise, but that avoids having to completely demangle
+# the symbol name. The outermost namespace is at the end of the identifier
+# mangling, and the identifier mangling is followed by the type mangling, so
+# we look for (llvm|clang)@@ followed by something that looks like a
+# function type mangling. To spot a function type we use (this is derived
+# from clang/lib/AST/MicrosoftMangle.cpp):
+# <function-type> ::= <function-class> <this-cvr-qualifiers>
+#                     <calling-convention> <return-type>
+#                     <argument-list> <throw-spec>
+# <function-class> ::= [A-Z]
+# <this-cvr-qualifiers> ::= [A-Z0-9_]*
+# <calling-convention> ::= [A-JQ]
+# <return-type> ::= .+
+# <argument-list> ::= X   (void)
+#                 ::= .+@ (list of types)
+#                 ::= .*Z (list of types, varargs)
+# <throw-spec> ::= exceptions are not allowed
+elif re.search('(llvm|clang)@@[A-Z][A-Z0-9_]*[A-JQ].+(X|.+@|.*Z)$', 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
+# Constructors and destructors of templates classes are assumed to be
+# defined in headers and not required to be kept
+if re.match('[CD][123]', names[-1][0]) and names[-2][1]:
+return None
+# Keep the instantiations of clang::Type::getAs, as some of them are
+# explipict specializations that are defined in clang's lib/AST/Type.cpp;
+# discard any other function template instantiations as it's assumed that
+# the definition is public
+elif symbol.startswith('_ZNK5clang4Type5getAs'):
+return symbol
+elif names[-1][1]:
+return None
+# 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
+def extract_symbols(arg):
+get_symbols, should_keep_symbol, calling_convention_decoration, lib = arg
+symbols = dict()
+for symbol in get_symbols(lib):
+symbol = should_keep_symbol(symbol, calling_convention_decoration)
+if symbol:
+symbols[symbol] = 1 + symbols.setdefault(symbol,0)
+return symbols
+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 = 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
+symbols = dict()
+for this_lib_symbols in libs_symbols:
+for k,v in list(this_lib_symbols.items()):
+symbols[k] = v + symbols.setdefault(k,0)
+# Count instances of member functions of template classes, and map the
+# symbol name to the function+class. We do this under the assumption that if
+# a member function of a template class is instantiated many times it's
+# probably declared in a public header file.
+template_function_count = dict()
+template_function_mapping = dict()
+template_function_count[""] = 0
+for k in symbols:
+name = None
+if args.mangling == 'microsoft':
+# Member functions of templates start with
+# ?<fn_name>@?$<class_name>@, so we map to <fn_name>@?$<class_name>.
+# As manglings go from the innermost scope to the outermost scope
+# this means:
+#  * When we have a function member of a subclass of a template
+#    class then <fn_name> will actually contain the mangling of
+#    both the subclass and the function member. This is fine.
+#  * When we have a function member of a template subclass of a
+#    (possibly template) class then it's the innermost template
+#    subclass that becomes <class_name>. This should be OK so long
+#    as we don't have multiple classes with a template subclass of
+#    the same name.
+match = re.search("^\?(\??\w+\@\?\$\w+)\@", k)
+if match:
+name = match.group(1)
+else:
+# Find member functions of templates by demangling the name and
+# checking if the second-to-last name in the list is a template.
+match = re.match('_Z(T[VTIS])?(N.+)', k)
+if match:
+try:
+names, _ = parse_itanium_nested_name(match.group(2))
+if names and names[-2][1]:
+name = ''.join([x for x,_ in names])
+except TooComplexName:
+# Manglings that are too complex should already have been
+# filtered out, but if we happen to somehow see one here
+# just leave it as-is.
+pass
+if name:
+old_count = template_function_count.setdefault(name,0)
+template_function_count[name] = old_count + 1
+template_function_mapping[k] = name
+else:
+template_function_mapping[k] = ""
+# Print symbols which both:
+#  * Appear in exactly one input, as symbols defined in multiple
+#    objects/libraries are assumed to have public definitions.
+#  * Aren't instances of member functions of templates which have been
+#    instantiated 100 times or more, which are assumed to have public
+#    definitions. (100 is an arbitrary guess here.)
+if args.o:
+outfile = open(args.o,'w')
+else:
+outfile = sys.stdout
+for k,v in list(symbols.items()):
+template_count = template_function_count[template_function_mapping[k]]
+if v == 1 and template_count < 100:
+print(k, file=outfile)

Mercurial > hg > CbC > CbC_llvm

comparison llvm/utils/extract_symbols.py @ 150:1d019706d866