Dexpreopt: prepare to merge class loader context from all deps.

The makefile implementation of dexpreopt is lagging behind the Soong
implementation in the way it handles transitive dependencies: Soong
propagates class loader context through transitive dependencies, such
as static libraries, but makefiles only propagate that information
through uses-library dependencies.

This discrepancy is caused by the difficulty of handling class loader
contexts in makefies: since there is no topological order in handling
module and its dependencies, the information is propagated via file
level dependencies on dexpreopt.configs and merged into the module's
dexpreopt.config with a python script.

To handle transitive dependencies correctly, it is necessary to
generate dexpreopt.config files for all libraries, not just those that
enable dexpreopt.

This change only prepares dex_preopt_odex_install.mk for that and
updates if for corresponding changes in manifest_check.py. It does not
enable generation of dexpreopt.config files for non uses-library
dependencies (e.g. static libraries). This will be done as a follow-up.

Changes:

  - renamed option for dependency dexpreopt.config files
  - added option for self dexpreopt.config
  - moved variable definitions so that they can be used both by
    uses-library check and dexpreopt command
  - add 'Optional' field in makefile-generated dexpreopt.config to
    align it on par with Soong-generated configs
  - modify dex_preopt_config_merger.py to add uses-libraries propagated
    via dexpreopt.config files

Bug: 214255490
Test: lunch aosp_cf_x86_64_phone-userdebug && m && launch_cvd \
    && adb wait-for-device && adb root \
    && adb logcat | grep -E 'ClassLoaderContext [a-z ]+ mismatch'
    # a few unrelated errors caused by missing optional uses-libraries
    #   android.net.ipsec.ike
    #   androidx.window.extensions
    #   androidx.window.sidecar
    # that were present before this patch
Change-Id: I6522319a8415f22f90fc96059a34675fb830e5cc

core/dex_preopt_config_merger.py

@@ -31,6 +31,7 @@ from __future__ import print_function
 
 import json
 from collections import OrderedDict
+import os
 import sys
 
 
@@ -42,8 +43,9 @@ def main():
   # Read all JSON configs.
   cfgs = []
   for arg in sys.argv[1:]:
-    with open(arg, 'r') as f:
-      cfgs.append(json.load(f, object_pairs_hook=OrderedDict))
+    if os.stat(arg).st_size != 0:
+      with open(arg, 'r') as f:
+        cfgs.append(json.load(f, object_pairs_hook=OrderedDict))
 
   # The first config is the dexpreopted library/app, the rest are its
   # <uses-library> dependencies.
@@ -88,6 +90,33 @@ def main():
       clcs2.append(clc)
     clc_map2[sdk_ver] = clcs2
 
+  # Go over all uses-libraries in dependency dexpreopt.config files (these don't
+  # have to be uses-libraries themselves, they can be e.g. transitive static
+  # library dependencies) and merge their CLC to the current one
+  for ulib, cfg in uses_libs.items():
+    any_sdk_ver = 'any' # not interested in compatibility libraries
+    clcs = cfg['ClassLoaderContexts'].get(any_sdk_ver, [])
+
+    # If the dependency is a uses-library itself, its uses-library dependencies
+    # are added as a subcontext, so don't add them to top-level CLC.
+    dep_is_a_uses_lib = False
+    for clc2 in clc_map2[any_sdk_ver]:
+      if clc2['Name'] == cfg['ProvidesUsesLibrary']:
+        dep_is_a_uses_lib = True
+    if dep_is_a_uses_lib:
+      continue
+
+    # Check if CLC for these libraries is already present (avoid duplicates).
+    # Don't bother optimizing quadratic loop, since CLC is typically small.
+    for clc in clcs:
+      already_in_clc = False
+      for clc2 in clc_map2[any_sdk_ver]:
+        if clc2['Name'] == clc['Name']:
+          already_in_clc = True
+          break
+      if not already_in_clc:
+        clc_map2[any_sdk_ver] += clcs
+
   # Overwrite the original class loader context with the patched one.
   cfg0['ClassLoaderContexts'] = clc_map2