src/share/vm/runtime/atomic.cpp

rev 7584 : code minimum

*** 26,50 ****
  #include "runtime/atomic.inline.hpp"
  
  /*
   * This is the default implementation of byte-sized cmpxchg. It emulates jbyte-sized cmpxchg
   * in terms of jint-sized cmpxchg. Platforms may override this by defining their own inline definition
!  * as well as defining VM_HAS_SPECIALIZED_CMPXCHG_BYTE. This will cause the platform specific
!  * implementation to be used instead.
   */
! jbyte Atomic::cmpxchg_general(jbyte exchange_value, volatile jbyte* dest, jbyte compare_value) {
    assert(sizeof(jbyte) == 1, "assumption.");
    uintptr_t dest_addr = (uintptr_t)dest;
    uintptr_t offset = dest_addr % sizeof(jint);
    volatile jint* dest_int = (volatile jint*)(dest_addr - offset);
    jint cur = *dest_int;
    jbyte* cur_as_bytes = (jbyte*)(&cur);
    jint new_val = cur;
    jbyte* new_val_as_bytes = (jbyte*)(&new_val);
    new_val_as_bytes[offset] = exchange_value;
    while (cur_as_bytes[offset] == compare_value) {
!     jint res = cmpxchg(new_val, dest_int, cur);
      if (res == cur) break;
      cur = res;
      new_val = cur;
      new_val_as_bytes[offset] = exchange_value;
    }
--- 26,49 ----
  #include "runtime/atomic.inline.hpp"
  
  /*
   * This is the default implementation of byte-sized cmpxchg. It emulates jbyte-sized cmpxchg
   * in terms of jint-sized cmpxchg. Platforms may override this by defining their own inline definition
!  * in their AtomicPlatform class.
   */
! jbyte AtomicBase::cmpxchg_general(jbyte exchange_value, volatile jbyte* dest, jbyte compare_value) {
    assert(sizeof(jbyte) == 1, "assumption.");
    uintptr_t dest_addr = (uintptr_t)dest;
    uintptr_t offset = dest_addr % sizeof(jint);
    volatile jint* dest_int = (volatile jint*)(dest_addr - offset);
    jint cur = *dest_int;
    jbyte* cur_as_bytes = (jbyte*)(&cur);
    jint new_val = cur;
    jbyte* new_val_as_bytes = (jbyte*)(&new_val);
    new_val_as_bytes[offset] = exchange_value;
    while (cur_as_bytes[offset] == compare_value) {
!     jint res = Atomic::cmpxchg(new_val, dest_int, cur);
      if (res == cur) break;
      cur = res;
      new_val = cur;
      new_val_as_bytes[offset] = exchange_value;
    }