Remove fixed contant pool entries by caching some global constants in Thread

runtime/vm/assembler_arm64.cc

Index: runtime/vm/assembler_arm64.cc
diff --git a/runtime/vm/assembler_arm64.cc b/runtime/vm/assembler_arm64.cc
index d82088b57292b135748780e29852aac9fffdcc13..37024d2d0dc5607cdbb105e03bea0953811182f3 100644
--- a/runtime/vm/assembler_arm64.cc
+++ b/runtime/vm/assembler_arm64.cc
@@ -31,28 +31,6 @@ Assembler::Assembler(bool use_far_branches)
       use_far_branches_(use_far_branches),
       comments_(),
       allow_constant_pool_(true) {
-  if (Isolate::Current() != Dart::vm_isolate()) {
-    // These objects and labels need to be accessible through every pool-pointer
-    // at the same index.
-    intptr_t index =
-        object_pool_wrapper_.AddObject(Object::null_object());
-    ASSERT(index == 0);
-
-    index = object_pool_wrapper_.AddObject(Bool::True());
-    ASSERT(index == 1);
-
-    index = object_pool_wrapper_.AddObject(Bool::False());
-    ASSERT(index == 2);
-
-    const Smi& vacant = Smi::Handle(Smi::New(0xfa >> kSmiTagShift));
-    StubCode* stub_code = Isolate::Current()->stub_code();
-    if (stub_code->UpdateStoreBuffer_entry() != NULL) {
-      object_pool_wrapper_.AddExternalLabel(
-          &stub_code->UpdateStoreBufferLabel(), kNotPatchable);
-    } else {
-      object_pool_wrapper_.AddObject(vacant);
-    }
-  }
 }
 
 
@@ -387,18 +365,10 @@ intptr_t Assembler::FindImmediate(int64_t imm) {
 }
 
 
-// A set of VM objects that are present in every constant pool.
-static bool IsAlwaysInConstantPool(const Object& object) {
-  // TODO(zra): Evaluate putting all VM heap objects into the pool.
-  return (object.raw() == Object::null())
-      || (object.raw() == Bool::True().raw())
-      || (object.raw() == Bool::False().raw());
-}
-
-
-bool Assembler::CanLoadObjectFromPool(const Object& object) {
+bool Assembler::CanLoadFromObjectPool(const Object& object) const {
+  ASSERT(!Thread::CanLoadFromThread(object));
   if (!allow_constant_pool()) {
-    return IsAlwaysInConstantPool(object);
+    return false;
   }
 
   // TODO(zra, kmillikin): Also load other large immediates from the object
@@ -458,7 +428,9 @@ void Assembler::LoadIsolate(Register dst, Register pp) {
 
 
 void Assembler::LoadObject(Register dst, const Object& object, Register pp) {
-  if (CanLoadObjectFromPool(object)) {
+  if (Thread::CanLoadFromThread(object)) {
+    ldr(dst, Address(THR, Thread::OffsetFromThread(object)));
+  } else if (CanLoadFromObjectPool(object)) {
     const int32_t offset =
         ObjectPool::element_offset(object_pool_wrapper_.FindObject(object));
     LoadWordFromPoolOffset(dst, pp, offset);
@@ -472,7 +444,10 @@ void Assembler::LoadObject(Register dst, const Object& object, Register pp) {
 
 
 void Assembler::CompareObject(Register reg, const Object& object, Register pp) {
-  if (CanLoadObjectFromPool(object)) {
+  if (Thread::CanLoadFromThread(object)) {
+    ldr(TMP, Address(THR, Thread::OffsetFromThread(object)));
+    CompareRegisters(reg, TMP);
+  } else if (CanLoadFromObjectPool(object)) {
     LoadObject(TMP, object, pp);
     CompareRegisters(reg, TMP);
   } else {
@@ -915,8 +890,8 @@ void Assembler::StoreIntoObject(Register object,
   if (object != R0) {
     mov(R0, object);
   }
-  StubCode* stub_code = Isolate::Current()->stub_code();
-  BranchLink(&stub_code->UpdateStoreBufferLabel(), PP);
+  ldr(TMP, Address(THR, Thread::update_store_buffer_entry_point_offset()));
+  blr(TMP);
   Pop(LR);
   if (value != R0) {
     // Restore R0.