commit dc21dea9b8b1157a4a9347b68301da4307c51168
author Adam Koski <adamkoski@google.com> Fri Jul 21 10:55:27 2017 -0700
committer Adam Koski <adamkoski@google.com> Fri Oct 20 16:25:18 2017 -0700
tree e5a861fbec159776bebc37296753ca21c7916593
parent 0d769d80a9a871cd4f0e5dc24e63c86d97fb3ad8

AAPT2: Produce Conditional Proguard Keep Rules

Add the option to produce keep rules that conditional keep based on
usage of R identifiers. This allows Proguard to potentially shrink more
code if resources are not used.

Currently only produces conditional rules for classes referenced in
layout resources because they are the most common and has the easiest
transitive usage chain to analyze.

Bug: 63628451
Test: make aapt2_tests and manual testing
Change-Id: I6c1af7affd64af40c80e004d8506a9463444b2c3

tools/aapt2/cmd/Link.cpp

diff --git a/tools/aapt2/cmd/Link.cpp b/tools/aapt2/cmd/Link.cpp
index 55a4c43..e0dae1b 100644
--- a/tools/aapt2/cmd/Link.cpp
+++ b/tools/aapt2/cmd/Link.cpp
@@ -96,6 +96,7 @@
   Maybe<std::string> generate_text_symbols_path;
   Maybe<std::string> generate_proguard_rules_path;
   Maybe<std::string> generate_main_dex_proguard_rules_path;
+  bool generate_conditional_proguard_rules = false;
   bool generate_non_final_ids = false;
   std::vector<std::string> javadoc_annotations;
   Maybe<std::string> private_symbols;
@@ -499,7 +500,7 @@
     return {};
   }
 
-  if (options_.update_proguard_spec && !proguard::CollectProguardRules(src, doc, keep_set_)) {
+  if (options_.update_proguard_spec && !proguard::CollectProguardRules(doc, keep_set_)) {
     return {};
   }
 
@@ -538,6 +539,8 @@
   bool error = false;
   std::map<std::pair<ConfigDescription, StringPiece>, FileOperation> config_sorted_files;
 
+  proguard::CollectResourceReferences(context_, table, keep_set_);
+
   for (auto& pkg : table->packages) {
     CHECK(!pkg->name.empty()) << "Packages must have names when being linked";
 
@@ -1719,7 +1722,8 @@
       }
     }
 
-    proguard::KeepSet proguard_keep_set;
+    proguard::KeepSet proguard_keep_set =
+        proguard::KeepSet(options_.generate_conditional_proguard_rules);
     proguard::KeepSet proguard_main_dex_keep_set;
 
     if (context_->GetPackageType() == PackageType::kStaticLib) {
@@ -1795,14 +1799,12 @@
       XmlReferenceLinker manifest_linker;
       if (manifest_linker.Consume(context_, manifest_xml.get())) {
         if (options_.generate_proguard_rules_path &&
-            !proguard::CollectProguardRulesForManifest(Source(options_.manifest_path),
-                                                       manifest_xml.get(), &proguard_keep_set)) {
+            !proguard::CollectProguardRulesForManifest(manifest_xml.get(), &proguard_keep_set)) {
           error = true;
         }
 
         if (options_.generate_main_dex_proguard_rules_path &&
-            !proguard::CollectProguardRulesForManifest(Source(options_.manifest_path),
-                                                       manifest_xml.get(),
+            !proguard::CollectProguardRulesForManifest(manifest_xml.get(),
                                                        &proguard_main_dex_keep_set, true)) {
           error = true;
         }
@@ -1919,6 +1921,9 @@
           .OptionalFlag("--proguard-main-dex",
                         "Output file for generated Proguard rules for the main dex.",
                         &options.generate_main_dex_proguard_rules_path)
+          .OptionalSwitch("--proguard-conditional-keep-rules",
+                          "Generate conditional Proguard keep rules.",
+                          &options.generate_conditional_proguard_rules)
           .OptionalSwitch("--no-auto-version",
                           "Disables automatic style and layout SDK versioning.",
                           &options.no_auto_version)