Convert kUseReadBarrier to static const from constexpr

This CL would compile both CC and userfaultfd GC in the art library,
enabling us to choose either of the two during boot time depending on
whether the device has userfaultfd kernel feature or not.

The CC GC is still chosen unless we use ART_USE_READ_BARRIER=false
during build time. This behavior will later be changed to choosing CC
*only* if ART_USE_READ_BARRIER=true is used. In other cases, if the
device has userfaultfd support then that GC will be chosen.

Bug: 160737021
Bug: 230021033
Test: art/test/testrunner/testrunner.py
Change-Id: I370f1a9f6b8cdff8c2ce3cf7aa936bccd7ed675f

1 files changed, 5 insertions, 5 deletions

diff --git a/runtime/class_linker.cc b/runtime/class_linker.cc
index 8921577a99..ccf4ff2704 100644
--- a/runtime/class_linker.cc
+++ b/runtime/class_linker.cc
@@ -2116,7 +2116,7 @@ void ClassLinker::VisitClassRoots(RootVisitor* visitor, VisitRootFlags flags) {
   const bool tracing_enabled = Trace::IsTracingEnabled();
   Thread* const self = Thread::Current();
   WriterMutexLock mu(self, *Locks::classlinker_classes_lock_);
-  if (kUseReadBarrier) {
+  if (gUseReadBarrier) {
     // We do not track new roots for CC.
     DCHECK_EQ(0, flags & (kVisitRootFlagNewRoots |
                           kVisitRootFlagClearRootLog |
@@ -2152,7 +2152,7 @@ void ClassLinker::VisitClassRoots(RootVisitor* visitor, VisitRootFlags flags) {
         root.VisitRoot(visitor, RootInfo(kRootVMInternal));
       }
     }
-  } else if (!kUseReadBarrier && (flags & kVisitRootFlagNewRoots) != 0) {
+  } else if (!gUseReadBarrier && (flags & kVisitRootFlagNewRoots) != 0) {
     for (auto& root : new_class_roots_) {
       ObjPtr<mirror::Class> old_ref = root.Read<kWithoutReadBarrier>();
       root.VisitRoot(visitor, RootInfo(kRootStickyClass));
@@ -2173,13 +2173,13 @@ void ClassLinker::VisitClassRoots(RootVisitor* visitor, VisitRootFlags flags) {
       }
     }
   }
-  if (!kUseReadBarrier && (flags & kVisitRootFlagClearRootLog) != 0) {
+  if (!gUseReadBarrier && (flags & kVisitRootFlagClearRootLog) != 0) {
     new_class_roots_.clear();
     new_bss_roots_boot_oat_files_.clear();
   }
-  if (!kUseReadBarrier && (flags & kVisitRootFlagStartLoggingNewRoots) != 0) {
+  if (!gUseReadBarrier && (flags & kVisitRootFlagStartLoggingNewRoots) != 0) {
     log_new_roots_ = true;
-  } else if (!kUseReadBarrier && (flags & kVisitRootFlagStopLoggingNewRoots) != 0) {
+  } else if (!gUseReadBarrier && (flags & kVisitRootFlagStopLoggingNewRoots) != 0) {
     log_new_roots_ = false;
   }
   // We deliberately ignore the class roots in the image since we