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, 5 insertions, 3 deletions

diff --git a/runtime/interpreter/interpreter_switch_impl.cc b/runtime/interpreter/interpreter_switch_impl.cc
index c6356485a9..5401495155 100644
--- a/runtime/interpreter/interpreter_switch_impl.cc
+++ b/runtime/interpreter/interpreter_switch_impl.cc
@@ -256,11 +256,12 @@ JValue ExecuteSwitchImpl(Thread* self, MethodHelper& mh, const DexFile::CodeItem
           }
           if (!obj_result->VerifierInstanceOf(return_type)) {
             // This should never happen.
+            std::string temp1, temp2;
             self->ThrowNewExceptionF(self->GetCurrentLocationForThrow(),
                                      "Ljava/lang/VirtualMachineError;",
                                      "Returning '%s' that is not instance of return type '%s'",
-                                     obj_result->GetClass()->GetDescriptor().c_str(),
-                                     return_type->GetDescriptor().c_str());
+                                     obj_result->GetClass()->GetDescriptor(&temp1),
+                                     return_type->GetDescriptor(&temp2));
             HANDLE_PENDING_EXCEPTION();
           }
         }
@@ -529,10 +530,11 @@ JValue ExecuteSwitchImpl(Thread* self, MethodHelper& mh, const DexFile::CodeItem
           ThrowNullPointerException(NULL, "throw with null exception");
         } else if (do_assignability_check && !exception->GetClass()->IsThrowableClass()) {
           // This should never happen.
+          std::string temp;
           self->ThrowNewExceptionF(self->GetCurrentLocationForThrow(),
                                    "Ljava/lang/VirtualMachineError;",
                                    "Throwing '%s' that is not instance of Throwable",
-                                   exception->GetClass()->GetDescriptor().c_str());
+                                   exception->GetClass()->GetDescriptor(&temp));
         } else {
           self->SetException(shadow_frame.GetCurrentLocationForThrow(), exception->AsThrowable());
         }