Moves the top_ and end_ words of the Scavenger into mutator thread.

runtime/vm/intrinsifier_arm.cc

Index: runtime/vm/intrinsifier_arm.cc
diff --git a/runtime/vm/intrinsifier_arm.cc b/runtime/vm/intrinsifier_arm.cc
index b053d0f4ae5cf36330d2c8ca8906f4c7a878ab09..6320d8c039b1e3f468bbd3eead3274c46c8e6e36 100644
--- a/runtime/vm/intrinsifier_arm.cc
+++ b/runtime/vm/intrinsifier_arm.cc
@@ -172,9 +172,8 @@ void Intrinsifier::GrowableArray_add(Assembler* assembler) {
       sizeof(Raw##type_name) + kObjectAlignment - 1;                           \
   __ AddImmediate(R2, fixed_size_plus_alignment_padding);                      \
   __ bic(R2, R2, Operand(kObjectAlignment - 1));                               \
-  Heap::Space space = Heap::kNew;                                              \
-  __ ldr(R3, Address(THR, Thread::heap_offset()));                             \
-  __ ldr(R0, Address(R3, Heap::TopOffset(space)));                             \
+  NOT_IN_PRODUCT(Heap::Space space = Heap::kNew);                              \
+  __ ldr(R0, Address(THR, Thread::top_offset()));                              \
                                                                                \
   /* R2: allocation size. */                                                   \
   __ adds(R1, R0, Operand(R2));                                                \
@@ -184,15 +183,14 @@ void Intrinsifier::GrowableArray_add(Assembler* assembler) {
   /* R0: potential new object start. */                                        \
   /* R1: potential next object start. */                                       \
   /* R2: allocation size. */                                                   \
-  /* R3: heap. */                                                              \
-  __ ldr(IP, Address(R3, Heap::EndOffset(space)));                             \
+  __ ldr(IP, Address(THR, Thread::end_offset()));                              \
   __ cmp(R1, Operand(IP));                                                     \
   __ b(&fall_through, CS);                                                     \
                                                                                \
   /* Successfully allocated the object(s), now update top to point to */       \
   /* next object start and initialize the object. */                           \
   NOT_IN_PRODUCT(__ LoadAllocationStatsAddress(R4, cid));                      \
-  __ str(R1, Address(R3, Heap::TopOffset(space)));                             \
+  __ str(R1, Address(THR, Thread::top_offset()));                              \
   __ AddImmediate(R0, kHeapObjectTag);                                         \
   /* Initialize the tags. */                                                   \
   /* R0: new object start as a tagged pointer. */                              \
@@ -1927,9 +1925,8 @@ static void TryAllocateOnebyteString(Assembler* assembler,
   __ bic(length_reg, length_reg, Operand(kObjectAlignment - 1));
 
   const intptr_t cid = kOneByteStringCid;
-  Heap::Space space = Heap::kNew;
-  __ ldr(R3, Address(THR, Thread::heap_offset()));
-  __ ldr(R0, Address(R3, Heap::TopOffset(space)));
+  NOT_IN_PRODUCT(Heap::Space space = Heap::kNew);
+  __ ldr(R0, Address(THR, Thread::top_offset()));
 
   // length_reg: allocation size.
   __ adds(R1, R0, Operand(length_reg));
@@ -1939,15 +1936,14 @@ static void TryAllocateOnebyteString(Assembler* assembler,
   // R0: potential new object start.
   // R1: potential next object start.
   // R2: allocation size.
-  // R3: heap.
-  __ ldr(NOTFP, Address(R3, Heap::EndOffset(space)));
+  __ ldr(NOTFP, Address(THR, Thread::end_offset()));
   __ cmp(R1, Operand(NOTFP));
   __ b(&fail, CS);
 
   // Successfully allocated the object(s), now update top to point to
   // next object start and initialize the object.
   NOT_IN_PRODUCT(__ LoadAllocationStatsAddress(R4, cid));
-  __ str(R1, Address(R3, Heap::TopOffset(space)));
+  __ str(R1, Address(THR, Thread::top_offset()));
   __ AddImmediate(R0, kHeapObjectTag);
 
   // Initialize the tags.