Trampoline and assembly fixes for ARM64

Trampolines need a jump, not a call. Expose br in the ARM64
assembler to allow this.

The resolution trampoline is called with the Quick ABI, and will
continue to a Quick ABI function. Then the method pointer must be
in x0.

Change-Id: I4e383b59d6c40a659d324a7faef3fadf0c890178
diff --git a/compiler/utils/arm64/assembler_arm64.cc b/compiler/utils/arm64/assembler_arm64.cc
index b364ba0..00ce923 100644
--- a/compiler/utils/arm64/assembler_arm64.cc
+++ b/compiler/utils/arm64/assembler_arm64.cc
@@ -468,6 +468,15 @@
   ___ Blr(reg_x(scratch.AsCoreRegister()));
 }
 
+void Arm64Assembler::JumpTo(ManagedRegister m_base, Offset offs, ManagedRegister m_scratch) {
+  Arm64ManagedRegister base = m_base.AsArm64();
+  Arm64ManagedRegister scratch = m_scratch.AsArm64();
+  CHECK(base.IsCoreRegister()) << base;
+  CHECK(scratch.IsCoreRegister()) << scratch;
+  LoadFromOffset(scratch.AsCoreRegister(), base.AsCoreRegister(), offs.Int32Value());
+  ___ Br(reg_x(scratch.AsCoreRegister()));
+}
+
 void Arm64Assembler::Call(FrameOffset base, Offset offs, ManagedRegister m_scratch) {
   Arm64ManagedRegister scratch = m_scratch.AsArm64();
   CHECK(scratch.IsCoreRegister()) << scratch;
diff --git a/compiler/utils/arm64/assembler_arm64.h b/compiler/utils/arm64/assembler_arm64.h
index 2bada3f..1c47e77 100644
--- a/compiler/utils/arm64/assembler_arm64.h
+++ b/compiler/utils/arm64/assembler_arm64.h
@@ -204,6 +204,9 @@
   void Call(FrameOffset base, Offset offset, ManagedRegister scratch);
   void Call(ThreadOffset offset, ManagedRegister scratch);
 
+  // Jump to address (not setting link register)
+  void JumpTo(ManagedRegister m_base, Offset offs, ManagedRegister m_scratch);
+
   // Generate code to check if Thread::Current()->exception_ is non-null
   // and branch to a ExceptionSlowPath if it is.
   void ExceptionPoll(ManagedRegister scratch, size_t stack_adjust);