Avoid use of std::string where we have const char*.

Removing the ClassHelper caused std::string creation for all calls to
Class::GetDescriptor and a significant performance regression. Make the
std::string an out argument so the caller can maintain it and its life time
while allowing GetDescriptor to return the common const char* case.

Don't generate GC maps when compilation is disabled.

Remove other uses of std::string that are occuring on critical paths.
Use the cheaper SkipClass in CompileMethod in CompilerDriver.
Specialize the utf8 as utf16 comparison code for the common shorter byte
encoding.
Force a bit of inlining, remove some UNLIKELYs (they are prone to pessimizing
code), add some LIKELYs.

x86-64 host 1-thread interpret-only of 57 apks:
Before: 29.539s
After: 23.467s

Regular compile:
Before: 1m35.347s
After: 1m20.056s

Bug: 16853450
Change-Id: Ic705ea24784bee24ab80084d06174cbf87d557ad

1 files changed, 8 insertions, 5 deletions

diff --git a/runtime/jni_internal.cc b/runtime/jni_internal.cc
index d5e92a4..b7d485e 100644
--- a/runtime/jni_internal.cc
+++ b/runtime/jni_internal.cc
@@ -84,9 +84,10 @@ static void ThrowNoSuchMethodError(ScopedObjectAccess& soa, mirror::Class* c,
                                    const char* name, const char* sig, const char* kind)
     SHARED_LOCKS_REQUIRED(Locks::mutator_lock_) {
   ThrowLocation throw_location = soa.Self()->GetCurrentLocationForThrow();
+  std::string temp;
   soa.Self()->ThrowNewExceptionF(throw_location, "Ljava/lang/NoSuchMethodError;",
                                  "no %s method \"%s.%s%s\"",
-                                 kind, c->GetDescriptor().c_str(), name, sig);
+                                 kind, c->GetDescriptor(&temp), name, sig);
 }
 
 static void ReportInvalidJNINativeMethod(const ScopedObjectAccess& soa, mirror::Class* c,
@@ -193,24 +194,26 @@ static jfieldID FindFieldID(const ScopedObjectAccess& soa, jclass jni_class, con
     StackHandleScope<1> hs(soa.Self());
     Handle<mirror::Throwable> cause(hs.NewHandle(soa.Self()->GetException(&throw_location)));
     soa.Self()->ClearException();
+    std::string temp;
     soa.Self()->ThrowNewExceptionF(throw_location, "Ljava/lang/NoSuchFieldError;",
                                    "no type \"%s\" found and so no field \"%s\" "
                                    "could be found in class \"%s\" or its superclasses", sig, name,
-                                   c->GetDescriptor().c_str());
+                                   c->GetDescriptor(&temp));
     soa.Self()->GetException(nullptr)->SetCause(cause.Get());
     return nullptr;
   }
+  std::string temp;
   if (is_static) {
     field = mirror::Class::FindStaticField(soa.Self(), c, name,
-                                           field_type->GetDescriptor().c_str());
+                                           field_type->GetDescriptor(&temp));
   } else {
-    field = c->FindInstanceField(name, field_type->GetDescriptor().c_str());
+    field = c->FindInstanceField(name, field_type->GetDescriptor(&temp));
   }
   if (field == nullptr) {
     ThrowLocation throw_location = soa.Self()->GetCurrentLocationForThrow();
     soa.Self()->ThrowNewExceptionF(throw_location, "Ljava/lang/NoSuchFieldError;",
                                    "no \"%s\" field \"%s\" in class \"%s\" or its superclasses",
-                                   sig, name, c->GetDescriptor().c_str());
+                                   sig, name, c->GetDescriptor(&temp));
     return nullptr;
   }
   return soa.EncodeField(field);