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#!/usr/bin/env python
#
# genv8constants.py output_file libv8_base.a
#
# Emits v8dbg constants stored in libv8_base.a in a format suitable for the V8
# ustack helper.
#
import re
import subprocess
import sys
if len(sys.argv) != 3:
print "usage: objsym.py outfile libv8_base.a"
sys.exit(2);
outfile = file(sys.argv[1], 'w');
pipe = subprocess.Popen([ 'objdump', '-z', '-D', sys.argv[2] ],
bufsize=-1, stdout=subprocess.PIPE).stdout;
pattern = re.compile('00000000 <(v8dbg_.*)>:');
numpattern = re.compile('[0-9a-fA-F]{2}');
outfile.write("""
/*
* File automatically generated by genv8constants. Do not edit.
*
* The following offsets are dynamically from libv8_base.a. See src/v8ustack.d
* for details on how these values are used.
*/
#ifndef V8_CONSTANTS_H
#define V8_CONSTANTS_H
#if defined(__i386)
""");
curr_sym = None;
curr_val = 0;
curr_octet = 0;
for line in pipe:
if curr_sym != None:
#
# This bit of code has nasty knowledge of the objdump text output
# format, but this is the most obvious robust approach. We could almost
# rely on looking at numbered fields, but some instructions look very
# much like hex numbers (e.g., "adc"), and we don't want to risk picking
# those up by mistake, so we look at character-based columns intead.
#
for i in range (0, 3):
# 6-character margin, 2-characters + 1 space for each field
idx = 6 + i * 3;
octetstr = line[idx:idx+2]
if not numpattern.match(octetstr):
break;
curr_val += int('0x%s' % octetstr, 16) << (curr_octet * 8);
curr_octet += 1;
if curr_octet < 4:
continue;
outfile.write("#define %s 0x%x\n" % (curr_sym.upper(), curr_val));
curr_sym = None;
curr_val = 0;
curr_octet = 0;
continue;
match = pattern.match(line)
if match == None:
continue;
curr_sym = match.group(1);
outfile.write("""
#else
#error "only i386 is supported for DTrace ustack helper"
#endif
#endif /* V8_CONSTANTS_H */
""");
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