Improve performance of stubcode based array allocation moving stub to isolate specific area.

runtime/vm/stub_code_arm64.cc

Index: runtime/vm/stub_code_arm64.cc
===================================================================
--- runtime/vm/stub_code_arm64.cc	(revision 36194)
+++ runtime/vm/stub_code_arm64.cc	(working copy)
@@ -612,111 +612,109 @@
 // The newly allocated object is returned in R0.
 void StubCode::GenerateAllocateArrayStub(Assembler* assembler) {
   Label slow_case;
-  if (FLAG_inline_alloc) {
-    // Compute the size to be allocated, it is based on the array length
-    // and is computed as:
-    // RoundedAllocationSize((array_length * kwordSize) + sizeof(RawArray)).
-    // Assert that length is a Smi.
-    __ tsti(R2, kSmiTagMask);
-    if (FLAG_use_slow_path) {
-      __ b(&slow_case);
-    } else {
-      __ b(&slow_case, NE);
-    }
-    __ cmp(R2, Operand(0));
-    __ b(&slow_case, LT);
-    __ LoadFieldFromOffset(R8, CTX, Context::isolate_offset(), kNoPP);
-    __ LoadFromOffset(R8, R8, Isolate::heap_offset(), kNoPP);
-    __ LoadFromOffset(R8, R8, Heap::new_space_offset(), kNoPP);
+  // Compute the size to be allocated, it is based on the array length
+  // and is computed as:
+  // RoundedAllocationSize((array_length * kwordSize) + sizeof(RawArray)).
+  // Assert that length is a Smi.
+  __ tsti(R2, kSmiTagMask);
+  if (FLAG_use_slow_path) {
+    __ b(&slow_case);
+  } else {
+    __ b(&slow_case, NE);
+  }
+  __ cmp(R2, Operand(0));
+  __ b(&slow_case, LT);
+  __ LoadFieldFromOffset(R8, CTX, Context::isolate_offset(), kNoPP);
+  __ LoadFromOffset(R8, R8, Isolate::heap_offset(), kNoPP);
+  __ LoadFromOffset(R8, R8, Heap::new_space_offset(), kNoPP);
 
-    // Calculate and align allocation size.
-    // Load new object start and calculate next object start.
-    // R1: array element type.
-    // R2: array length as Smi.
-    // R8: points to new space object.
-    __ LoadFromOffset(R0, R8, Scavenger::top_offset(), kNoPP);
-    intptr_t fixed_size = sizeof(RawArray) + kObjectAlignment - 1;
-    __ LoadImmediate(R3, fixed_size, kNoPP);
-    __ add(R3, R3, Operand(R2, LSL, 2));  // R2 is Smi.
-    ASSERT(kSmiTagShift == 1);
-    __ andi(R3, R3, ~(kObjectAlignment - 1));
-    __ adds(R7, R3, Operand(R0));
-    __ b(&slow_case, VS);
+  // Calculate and align allocation size.
+  // Load new object start and calculate next object start.
+  // R1: array element type.
+  // R2: array length as Smi.
+  // R8: points to new space object.
+  __ LoadFromOffset(R0, R8, Scavenger::top_offset(), kNoPP);
+  intptr_t fixed_size = sizeof(RawArray) + kObjectAlignment - 1;
+  __ LoadImmediate(R3, fixed_size, kNoPP);
+  __ add(R3, R3, Operand(R2, LSL, 2));  // R2 is Smi.
+  ASSERT(kSmiTagShift == 1);
+  __ andi(R3, R3, ~(kObjectAlignment - 1));
+  __ adds(R7, R3, Operand(R0));
+  __ b(&slow_case, VS);
 
-    // Check if the allocation fits into the remaining space.
-    // R0: potential new object start.
-    // R1: array element type.
-    // R2: array length as Smi.
-    // R3: array size.
-    // R7: potential next object start.
-    // R8: points to new space object.
-    __ LoadFromOffset(TMP, R8, Scavenger::end_offset(), kNoPP);
-    __ CompareRegisters(R7, TMP);
-    __ b(&slow_case, CS);  // Branch if unsigned higher or equal.
+  // Check if the allocation fits into the remaining space.
+  // R0: potential new object start.
+  // R1: array element type.
+  // R2: array length as Smi.
+  // R3: array size.
+  // R7: potential next object start.
+  // R8: points to new space object.
+  __ LoadFromOffset(TMP, R8, Scavenger::end_offset(), kNoPP);
+  __ CompareRegisters(R7, TMP);
+  __ b(&slow_case, CS);  // Branch if unsigned higher or equal.
 
-    // Successfully allocated the object(s), now update top to point to
-    // next object start and initialize the object.
-    // R0: potential new object start.
-    // R3: array size.
-    // R7: potential next object start.
-    // R8: Points to new space object.
-    __ StoreToOffset(R7, R8, Scavenger::top_offset(), kNoPP);
-    __ add(R0, R0, Operand(kHeapObjectTag));
-    __ UpdateAllocationStatsWithSize(kArrayCid, R3, R8, kNoPP);
+  // Successfully allocated the object(s), now update top to point to
+  // next object start and initialize the object.
+  // R0: potential new object start.
+  // R3: array size.
+  // R7: potential next object start.
+  // R8: Points to new space object.
+  __ StoreToOffset(R7, R8, Scavenger::top_offset(), kNoPP);
+  __ add(R0, R0, Operand(kHeapObjectTag));
+  __ UpdateAllocationStatsWithSize(kArrayCid, R3, R8, kNoPP);
 
-    // R0: new object start as a tagged pointer.
-    // R1: array element type.
-    // R2: array length as Smi.
-    // R3: array size.
-    // R7: new object end address.
+  // R0: new object start as a tagged pointer.
+  // R1: array element type.
+  // R2: array length as Smi.
+  // R3: array size.
+  // R7: new object end address.
 
-    // Store the type argument field.
-    __ StoreIntoObjectOffsetNoBarrier(
-        R0, Array::type_arguments_offset(), R1, PP);
+  // Store the type argument field.
+  __ StoreIntoObjectOffsetNoBarrier(
+      R0, Array::type_arguments_offset(), R1, PP);
 
-    // Set the length field.
-    __ StoreIntoObjectOffsetNoBarrier(R0, Array::length_offset(), R2, PP);
+  // Set the length field.
+  __ StoreIntoObjectOffsetNoBarrier(R0, Array::length_offset(), R2, PP);
 
-    // Calculate the size tag.
-    // R0: new object start as a tagged pointer.
-    // R2: array length as Smi.
-    // R3: array size.
-    // R7: new object end address.
-    const intptr_t shift = RawObject::kSizeTagPos - kObjectAlignmentLog2;
-    __ CompareImmediate(R3, RawObject::SizeTag::kMaxSizeTag, kNoPP);
-    // If no size tag overflow, shift R1 left, else set R1 to zero.
-    __ Lsl(TMP, R3, shift);
-    __ csel(R1, TMP, R1, LS);
-    __ csel(R1, ZR, R1, HI);
+  // Calculate the size tag.
+  // R0: new object start as a tagged pointer.
+  // R2: array length as Smi.
+  // R3: array size.
+  // R7: new object end address.
+  const intptr_t shift = RawObject::kSizeTagPos - kObjectAlignmentLog2;
+  __ CompareImmediate(R3, RawObject::SizeTag::kMaxSizeTag, kNoPP);
+  // If no size tag overflow, shift R1 left, else set R1 to zero.
+  __ Lsl(TMP, R3, shift);
+  __ csel(R1, TMP, R1, LS);
+  __ csel(R1, ZR, R1, HI);
 
-    // Get the class index and insert it into the tags.
-    __ LoadImmediate(TMP, RawObject::ClassIdTag::encode(kArrayCid), kNoPP);
-    __ orr(R1, R1, Operand(TMP));
-    __ StoreFieldToOffset(R1, R0, Array::tags_offset(), kNoPP);
+  // Get the class index and insert it into the tags.
+  __ LoadImmediate(TMP, RawObject::ClassIdTag::encode(kArrayCid), kNoPP);
+  __ orr(R1, R1, Operand(TMP));
+  __ StoreFieldToOffset(R1, R0, Array::tags_offset(), kNoPP);
 
-    // Initialize all array elements to raw_null.
-    // R0: new object start as a tagged pointer.
-    // R7: new object end address.
-    // R2: array length as Smi.
-    __ AddImmediate(R1, R0, Array::data_offset() - kHeapObjectTag, kNoPP);
-    // R1: iterator which initially points to the start of the variable
-    // data area to be initialized.
-    __ LoadObject(TMP, Object::null_object(), PP);
-    Label loop, done;
-    __ Bind(&loop);
-    // TODO(cshapiro): StoreIntoObjectNoBarrier
-    __ CompareRegisters(R1, R7);
-    __ b(&done, CS);
-    __ str(TMP, Address(R1));  // Store if unsigned lower.
-    __ AddImmediate(R1, R1, kWordSize, kNoPP);
-    __ b(&loop);  // Loop until R1 == R7.
-    __ Bind(&done);
+  // Initialize all array elements to raw_null.
+  // R0: new object start as a tagged pointer.
+  // R7: new object end address.
+  // R2: array length as Smi.
+  __ AddImmediate(R1, R0, Array::data_offset() - kHeapObjectTag, kNoPP);
+  // R1: iterator which initially points to the start of the variable
+  // data area to be initialized.
+  __ LoadObject(TMP, Object::null_object(), PP);
+  Label loop, done;
+  __ Bind(&loop);
+  // TODO(cshapiro): StoreIntoObjectNoBarrier
+  __ CompareRegisters(R1, R7);
+  __ b(&done, CS);
+  __ str(TMP, Address(R1));  // Store if unsigned lower.
+  __ AddImmediate(R1, R1, kWordSize, kNoPP);
+  __ b(&loop);  // Loop until R1 == R7.
+  __ Bind(&done);
 
-    // Done allocating and initializing the array.
-    // R0: new object.
-    // R2: array length as Smi (preserved for the caller.)
-    __ ret();
-  }
+  // Done allocating and initializing the array.
+  // R0: new object.
+  // R2: array length as Smi (preserved for the caller.)
+  __ ret();
 
   // Unable to allocate the array using the fast inline code, just call
   // into the runtime.