src/hotspot/cpu/aarch64/gc/shenandoah/shenandoahBarrierSetAssembler_aarch64.cpp

rev 53052 : [mq]: asm.patch

*** 689,693 ****
--- 689,717 ----
      StubCodeGenerator cgen(&buf);
      _shenandoah_wb = generate_shenandoah_wb(&cgen, false, true);
      _shenandoah_wb_C = generate_shenandoah_wb(&cgen, true, !ShenandoahWriteBarrierCsetTestInIR);
    }
  }
+ 
+ bool ShenandoahBarrierSetAssembler::needs_explicit_null_check(intptr_t offset) {
+   // AArch64 addresses passed from the signal handler may have
+   // their top 8 bits zeroed. That affects the case where
+   // Shenandoah tries to load a Brooks pointer via a null oop.
+   const uintptr_t address_bits = (uintptr_t)0xfffffffffffful;
+   if (UseCompressedOops && Universe::narrow_oop_base() != NULL) {
+     assert (Universe::heap() != NULL, "java heap should be initialized");
+     // The first page after heap_base is unmapped and
+     // the 'offset' is equal to [heap_base + offset] for
+     // narrow oop implicit null checks.
+     uintptr_t base = (uintptr_t) Universe::narrow_oop_base();
+     int adj = BrooksPointer::byte_offset();
+     if ((uintptr_t) ((offset - adj) & address_bits) >= base) {
+       // Normalize offset for the next check.
+       offset = (intptr_t) (pointer_delta((void *) offset, (void *) base, 1));
+     }
+   }
+ 
+   if ((offset & address_bits) == (BrooksPointer::byte_offset() & address_bits)) {
+     return false;
+   }
+   return offset < 0 || os::vm_page_size() <= offset;
+ ble}
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