src/hotspot/share/asm/assembler.cpp

rev 52430 : 8213199: GC abstraction for Assembler::needs_explicit_null_check()

*** 24,33 ****
--- 24,34 ----
  
  #include "precompiled.hpp"
  #include "asm/codeBuffer.hpp"
  #include "asm/macroAssembler.hpp"
  #include "asm/macroAssembler.inline.hpp"
+ #include "gc/shared/collectedHeap.hpp"
  #include "runtime/atomic.hpp"
  #include "runtime/icache.hpp"
  #include "runtime/os.hpp"
  #include "runtime/thread.hpp"
  
*** 305,327 ****
      return code_section()->outer()->code_string(str);
    }
    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 _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();
!     if ((uintptr_t)offset >= base) {
!       // Normalize offset for the next check.
!       offset = (intptr_t)(pointer_delta((void*)offset, (void*)base, 1));
      }
    }
  #endif
!   return offset < 0 || os::vm_page_size() <= offset;
  }
--- 306,339 ----
      return code_section()->outer()->code_string(str);
    }
    return NULL;
  }
  
! bool MacroAssembler::uses_implicit_null_check(void* address) {
    // Exception handler checks the nmethod's implicit null checks table
    // only when this method returns false.
+   intptr_t int_address = reinterpret_cast<intptr_t>(address);
+   intptr_t cell_header_size = Universe::heap()->cell_header_size();
+   size_t region_size = os::vm_page_size() + cell_header_size;
  #ifdef _LP64
    if (UseCompressedOops && Universe::narrow_oop_base() != NULL) {
!     // A SEGV can legitimately happen in C2 code at address
!     // (heap_base + offset) if  Matcher::narrow_oop_use_complex_address
!     // is configured to allow narrow oops field loads to be implicitly
!     // null checked
!     intptr_t start = ((intptr_t)Universe::narrow_oop_base()) - cell_header_size;
!     intptr_t end = start + region_size;
!     if (int_address >= start && int_address < end) {
!       return true;
      }
    }
  #endif
!   intptr_t start = -cell_header_size;
!   intptr_t end = start + region_size;
!   return int_address >= start && int_address < end;
! }
! 
! bool MacroAssembler::needs_explicit_null_check(intptr_t offset) {
!   // Check if offset is outside of [-cell_header_size, os::vm_page_size)
!   return offset < -Universe::heap()->cell_header_size() ||
!          offset >= os::vm_page_size();
  }