ART Faster `LinkCode()` in `ClassLinker`.

Make `LinkCode()` a member of `ClassLinker` and speed it up
by avoiding a linear (but fast) method code lookup using the
`BitVector::NumSetBits()`, avoiding related function call
overhead as well as pulling some invariant checks out of the
calling loops and eliminating redundant checks.

For a test class with 1000 unannotated static methods and
400 @NeverCompile static methods, this change reduces the
time needed by `ClassLinker::LoadClass()` by roughly 25%.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Bug: 329196666
Change-Id: Ifeae520113594acae2e5c19ba746f11ede2dfac2

1 files changed, 5 insertions, 0 deletions

diff --git a/runtime/class_linker.h b/runtime/class_linker.h
index edb866adc7..4b886e9f04 100644
--- a/runtime/class_linker.h
+++ b/runtime/class_linker.h
@@ -925,6 +925,7 @@ class EXPORT ClassLinker {
   template <PointerSize kPointerSize>
   class LinkMethodsHelper;
   class MethodAnnotationsIterator;
+  class OatClassCodeIterator;
   class VisiblyInitializedCallback;
 
   struct ClassLoaderData {
@@ -1048,6 +1049,10 @@ class EXPORT ClassLinker {
                   /*out*/ ArtMethod* dst)
       REQUIRES_SHARED(Locks::mutator_lock_);
 
+  void LinkCode(ArtMethod* method,
+                uint32_t class_def_method_index,
+                /*inout*/ OatClassCodeIterator* occi) REQUIRES_SHARED(Locks::mutator_lock_);
+
   void FixupStaticTrampolines(Thread* self, ObjPtr<mirror::Class> klass)
       REQUIRES_SHARED(Locks::mutator_lock_);