src/hotspot/share/asm/assembler.cpp

rev 53052 : [mq]: asm.patch

*** 307,344 ****
    }
    return NULL;
  }
  
  bool MacroAssembler::needs_explicit_null_check(intptr_t offset) {
!   // Exception handler checks the nmethod's implicit null checks table
!   // only when this method returns false.
! #ifdef AARCH64
!   // 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;
! #else
!   const uintptr_t address_bits = ~(uintptr_t)0;
! #endif
! #ifdef _LP64
!   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 = MIN2(0, UseShenandoahGC ? BrooksPointer::byte_offset() : 0);
!     if ((uintptr_t)((offset - adj) & address_bits) >= base) {
!       // Normalize offset for the next check.
!       offset = (intptr_t)(pointer_delta((void*)offset, (void*)base, 1));
!     }
!   }
! #endif
! 
!   if (UseShenandoahGC) {
!     if ((offset & address_bits) == (BrooksPointer::byte_offset() & address_bits)) {
!       return false;
!     }
!   }
! 
!   return offset < 0 || os::vm_page_size() <= offset;
  }
--- 307,313 ----
    }
    return NULL;
  }
  
  bool MacroAssembler::needs_explicit_null_check(intptr_t offset) {
!   return BarrierSet::barrier_set()->barrier_set_assembler()->needs_explicit_null_check(offset);
  }