Precompilation: canonicalize Instructions in PRODUCT mode.

runtime/vm/precompiler.cc

Index: runtime/vm/precompiler.cc
diff --git a/runtime/vm/precompiler.cc b/runtime/vm/precompiler.cc
index 61470ad7f44fb4b8616c7d1267607f10f03519dc..2df113f5e0e30f03c321ae5d7b6afb598449c7fd 100644
--- a/runtime/vm/precompiler.cc
+++ b/runtime/vm/precompiler.cc
@@ -129,6 +129,11 @@ void Precompiler::DoCompileAll(
     DedupStackmaps();
     DedupStackmapLists();
 
+#if defined(PRODUCT)

[Ivan Posva, 2016/02/04 18:00:03]

Please use a release flag to control this. This will allow for easier testing
and development.

[rmacnak, 2016/02/04 19:29:47]

Done.

+    // Reduces binary size but obfuscates profiler results.
+    DedupInstructions();
+#endif
+
     I->object_store()->set_compile_time_constants(Array::null_array());
     I->object_store()->set_unique_dynamic_targets(Array::null_array());
 
@@ -1188,6 +1193,52 @@ void Precompiler::DedupStackmapLists() {
 }
 
 
+void Precompiler::DedupInstructions() {
+  class DedupInstructionsVisitor : public FunctionVisitor {
+   public:
+    explicit DedupInstructionsVisitor(Zone* zone) :
+      zone_(zone),
+      canonical_instructions_(),
+      code_(Code::Handle(zone)),
+      instructions_(Instructions::Handle(zone)) {
+    }
+
+    void VisitFunction(const Function& function) {
+      if (!function.HasCode()) {
+        ASSERT(function.HasImplicitClosureFunction());
+        return;
+      }
+      code_ = function.CurrentCode();
+      instructions_ = code_.instructions();
+      instructions_ = DedupInstructions(instructions_);

[Ivan Posva, 2016/02/04 18:00:03]

This function is a bit unfortunately named due to it being a duplicate name.

[rmacnak, 2016/02/04 19:29:47]

Changed to DedupOneInstructions

+      code_.SetActiveInstructions(instructions_.raw());
+      code_.set_instructions(instructions_.raw());
+      function.SetInstructions(code_);  // Update cached entry point.
+    }
+
+    RawInstructions* DedupInstructions(const Instructions& instructions) {
+      const Instructions* set_instructions =
+          canonical_instructions_.Lookup(&instructions);
+      if (set_instructions == NULL) {
+        canonical_instructions_.Insert(
+            &Instructions::ZoneHandle(zone_, instructions.raw()));
+        return instructions.raw();
+      } else {
+        return set_instructions->raw();

[Ivan Posva, 2016/02/04 18:00:03]

cached_instructions?

[rmacnak, 2016/02/04 19:29:47]

Changed to canonical_instructions_ and changed canonical_instructions_ to
canoncial_instructions_set_.

+      }
+    }
+
+   private:
+    Zone* zone_;
+    InstructionsSet canonical_instructions_;
+    Code& code_;
+    Instructions& instructions_;
+  };
+
+  DedupInstructionsVisitor visitor(Z);
+  VisitFunctions(&visitor);
+}
+
 void Precompiler::VisitFunctions(FunctionVisitor* visitor) {
   Library& lib = Library::Handle(Z);
   Class& cls = Class::Handle(Z);