Track JS allocations as they arrive with no affection on performance when tracking is switched off

src/x64/code-stubs-x64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 4923 matching lines @@
     __ j(less, &copy_routine);
     // Allocate new sliced string.  At this point we do not reload the instance
     // type including the string encoding because we simply rely on the info
     // provided by the original string.  It does not matter if the original
     // string's encoding is wrong because we always have to recheck encoding of
     // the newly created string's parent anyways due to externalized strings.
     Label two_byte_slice, set_slice_header;
     STATIC_ASSERT((kStringEncodingMask & kOneByteStringTag) != 0);
     STATIC_ASSERT((kStringEncodingMask & kTwoByteStringTag) == 0);
     __ testb(rbx, Immediate(kStringEncodingMask));
-    __ j(zero, &two_byte_slice, Label::kNear);
+    // Make long jumps when allocations tracking is on due to
+    // RecordObjectAllocation inside MacroAssembler::Allocate.
+    Label::Distance jump_distance =
+        masm->isolate()->heap_profiler()->is_tracking_allocations()
+        ? Label::kFar
+        : Label::kNear;
+    __ j(zero, &two_byte_slice, jump_distance);
     __ AllocateAsciiSlicedString(rax, rbx, r14, &runtime);
-    __ jmp(&set_slice_header, Label::kNear);
+    __ jmp(&set_slice_header, jump_distance);
     __ bind(&two_byte_slice);
     __ AllocateTwoByteSlicedString(rax, rbx, r14, &runtime);
     __ bind(&set_slice_header);
     __ Integer32ToSmi(rcx, rcx);
     __ movq(FieldOperand(rax, SlicedString::kLengthOffset), rcx);
     __ movq(FieldOperand(rax, SlicedString::kHashFieldOffset),
            Immediate(String::kEmptyHashField));
     __ movq(FieldOperand(rax, SlicedString::kParentOffset), rdi);
     __ movq(FieldOperand(rax, SlicedString::kOffsetOffset), rdx);
     __ IncrementCounter(counters->sub_string_native(), 1);
@@ skipping 1589 matching lines @@
   __ bind(&fast_elements_case);
   GenerateCase(masm, FAST_ELEMENTS);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64