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, 1 deletions

diff --git a/compiler/dex/verification_results.cc b/compiler/dex/verification_results.cc
index a7f67e73ba..a8e6b3c8df 100644
--- a/compiler/dex/verification_results.cc
+++ b/compiler/dex/verification_results.cc
@@ -30,7 +30,8 @@
 namespace art {
 
 VerificationResults::VerificationResults(const CompilerOptions* compiler_options)
-    : verified_methods_lock_("compiler verified methods lock"),
+    : compiler_options_(compiler_options),
+      verified_methods_lock_("compiler verified methods lock"),
       verified_methods_(),
       rejected_classes_lock_("compiler rejected classes lock"),
       rejected_classes_() {
@@ -106,6 +107,9 @@ bool VerificationResults::IsCandidateForCompilation(MethodReference& method_ref,
     return true;
   }
 #endif
+  if (!compiler_options_->IsCompilationEnabled()) {
+    return false;
+  }
   // Don't compile class initializers, ever.
   if (((access_flags & kAccConstructor) != 0) && ((access_flags & kAccStatic) != 0)) {
     return false;