Output a linker map file for official builds

build/toolchain/gcc_solink_wrapper.py

Index: build/toolchain/gcc_solink_wrapper.py
diff --git a/build/toolchain/gcc_solink_wrapper.py b/build/toolchain/gcc_solink_wrapper.py
index 426f9d66332ca34b755d112e4070864b0e4a0a7d..e7782b253c0b0b56ba6310e090e3b7233a8e994a 100755
--- a/build/toolchain/gcc_solink_wrapper.py
+++ b/build/toolchain/gcc_solink_wrapper.py
@@ -11,9 +11,12 @@ does not have a POSIX-like shell (e.g. Windows).
 """
 
 import argparse
+import gzip
 import os
+import shutil
 import subprocess
 import sys
+import threading
 
 import wrapper_utils
 
@@ -57,6 +60,18 @@ def UpdateTOC(tocfile, toc):
     open(tocfile, 'w').write(toc)
 
 
+def _GzipHelper(src_path, dest_path):
+  # Results for Android map file with GCC on a z620:
+  # Uncompressed: 207MB
+  # gzip -9: 16.4MB, takes 8.7 seconds.
+  # gzip -1: 21.8MB, takes 2.0 seconds.
+  # Piping directly from the linker via -print-map (or via -Map with a fifo)
+  # adds a whopping 30-45 seconds!
+  with open(src_path, 'rb') as f_in, gzip.GzipFile(dest_path, 'wb', 1) as f_out:
+    shutil.copyfileobj(f_in, f_out)
+  os.unlink(src_path)
+
+
 def main():
   parser = argparse.ArgumentParser(description=__doc__)
   parser.add_argument('--readelf',
@@ -78,6 +93,10 @@ def main():
                       required=True,
                       help='Output table-of-contents file',
                       metavar='FILE')
+  parser.add_argument('--mapfile',
+                      help=('Use --Wl,-Map to generate a map file. Will be '
+                            'gzipped if extension ends with .gz'),
+                      metavar='FILE')
   parser.add_argument('--output',
                       required=True,
                       help='Final output shared object file',
@@ -99,8 +118,21 @@ def main():
         whitelist_candidates, args.resource_whitelist)
 
   # First, run the actual link.
-  result = subprocess.call(
-      wrapper_utils.CommandToRun(args.command), env=fast_env)
+  command = wrapper_utils.CommandToRun(args.command)
+  tmp_map_path = None
+  if args.mapfile and args.mapfile.endswith('.gz'):
+    tmp_map_path = args.mapfile + '.tmp'
+    command.append('-Wl,-Map,' + tmp_map_path)
+  elif args.mapfile:
+    command.append('-Wl,-Map,' + args.mapfile)
+  result = subprocess.call(command, env=fast_env)
+
+  if tmp_map_path and result == 0:
+    threading.Thread(
+        target=lambda: _GzipHelper(tmp_map_path, args.mapfile)).start()
+  elif tmp_map_path and os.path.exists(tmp_map_file):
+    os.unlink(tmp_map_file)
+
   if result != 0:
     return result