Fix objdump assembly truncations

tools/objdump-v8

 #!/usr/bin/env python
 #
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+import os.path
 import re
 import subprocess
 import sys
 
 
 def get_address_bounds():
   start = -1
   end = -1
   for arg in sys.argv:
     if arg.startswith("--start-address="):
       start = int(arg[-12:], 16)
     if arg.startswith("--stop-address="):
       end = int(arg[-12:], 16)
   return start, end
 
 
 def format_line(line):
   pieces = line.split(None, 3)
   return " " + pieces[0][2:] + ":\t" + pieces[3]
 
 
 def is_comment(line):
   stripped = line.strip()
-  return stripped.startswith("--") or stripped.startswith(";;;")
+  return stripped.startswith("--") or stripped.startswith(";;")
 
 def main():
   filename = sys.argv[-1]
   match = re.match(r"/tmp/perf-(.*)\.map", filename)
   if match:
     start, end = get_address_bounds()
-    codefile = "code-" + match.group(1) + "-1.asm"
-    with open(codefile, "r") as code:
+    if os.path.exists("code.asm"):
+      codefile = open("code.asm", "r")

[Benedikt Meurer, 2016/07/21 17:28:26]

I think you should prefer the code-<pid>-<isolate id>.asm version. That's less
likely to be outdated. :-)

+    else:
+      codefile = open("code-" + match.group(1) + "-1.asm", "r")
+    with codefile:
       printing = False
-      for line in code:
+      for line in codefile:
         if line.startswith("0x"):
           addr = int(line.split()[0], 0)
           if start <= addr <= end:
             printing = True
             sys.stdout.write(format_line(line))
           elif printing:
             break
         elif printing and not is_comment(line):
           break
   else:
     sys.argv[0] = "objdump"
     sys.exit(subprocess.call(sys.argv))
 
 if __name__ == "__main__":
   main()