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/base/mutex-inl.h b/runtime/base/mutex-inl.h
index 3e5cdbadba..f70db35f1c 100644
--- a/runtime/base/mutex-inl.h
+++ b/runtime/base/mutex-inl.h
@@ -51,9 +51,11 @@ class ScopedContentionRecorder {
         blocked_tid_(kLogLockContentions ? blocked_tid : 0),
         owner_tid_(kLogLockContentions ? owner_tid : 0),
         start_nano_time_(kLogLockContentions ? NanoTime() : 0) {
-    std::string msg = StringPrintf("Lock contention on %s (owner tid: %" PRIu64 ")",
-                                   mutex->GetName(), owner_tid);
-    ATRACE_BEGIN(msg.c_str());
+    if (ATRACE_ENABLED()) {
+      std::string msg = StringPrintf("Lock contention on %s (owner tid: %" PRIu64 ")",
+                                     mutex->GetName(), owner_tid);
+      ATRACE_BEGIN(msg.c_str());
+    }
   }
 
   ~ScopedContentionRecorder() {