Remove method verification results right after compiling a method

This saves memory since it allows the code arrays from methods
compiled in future methods to use the ram we just freed from the
verification results.

GmsCore.apk:
Before: dex2oat took 77.383s (threads: 2) arena alloc=6MB java alloc=30MB native alloc=77MB free=13KB
After:  dex2oat took 72.180s (threads: 2) arena alloc=6MB java alloc=30MB native alloc=60MB free=13KB

Bug: 18596910
Change-Id: I5d6df380e4fe58751a2b304202083f4d30b33b7c
(cherry picked from commit 25fda92083d5b93b38cc1f6b12ac6a44d992d6a4)
diff --git a/compiler/dex/quick/codegen_util.cc b/compiler/dex/quick/codegen_util.cc
index 58bcee2..0021754 100644
--- a/compiler/dex/quick/codegen_util.cc
+++ b/compiler/dex/quick/codegen_util.cc
@@ -775,6 +775,10 @@
         ": " << PrettyMethod(cu_->method_idx, *cu_->dex_file);
     native_gc_map_builder.AddEntry(native_offset, references);
   }
+
+  // Maybe not necessary, but this could help prevent errors where we access the verified method
+  // after it has been deleted.
+  mir_graph_->GetCurrentDexCompilationUnit()->ClearVerifiedMethod();
 }
 
 /* Determine the offset of each literal field */
diff --git a/compiler/dex/verification_results.cc b/compiler/dex/verification_results.cc
index 4929b5b..932a532 100644
--- a/compiler/dex/verification_results.cc
+++ b/compiler/dex/verification_results.cc
@@ -84,6 +84,15 @@
   return (it != verified_methods_.end()) ? it->second : nullptr;
 }
 
+void VerificationResults::RemoveVerifiedMethod(MethodReference ref) {
+  WriterMutexLock mu(Thread::Current(), verified_methods_lock_);
+  auto it = verified_methods_.find(ref);
+  if (it != verified_methods_.end()) {
+    delete it->second;
+    verified_methods_.erase(it);
+  }
+}
+
 void VerificationResults::AddRejectedClass(ClassReference ref) {
   {
     WriterMutexLock mu(Thread::Current(), rejected_classes_lock_);
diff --git a/compiler/dex/verification_results.h b/compiler/dex/verification_results.h
index 0e7923f..7fc2a23 100644
--- a/compiler/dex/verification_results.h
+++ b/compiler/dex/verification_results.h
@@ -48,6 +48,7 @@
 
     const VerifiedMethod* GetVerifiedMethod(MethodReference ref)
         LOCKS_EXCLUDED(verified_methods_lock_);
+    void RemoveVerifiedMethod(MethodReference ref) LOCKS_EXCLUDED(verified_methods_lock_);
 
     void AddRejectedClass(ClassReference ref) LOCKS_EXCLUDED(rejected_classes_lock_);
     bool IsClassRejected(ClassReference ref) LOCKS_EXCLUDED(rejected_classes_lock_);