src/hotspot/cpu/aarch64/aarch64.ad

rev 53382 : 8217368: AArch64: C2 recursive stack locking optimisation not triggered
Reviewed-by: duke

*** 3418,3453 ****
      }
  
      // Handle existing monitor
      __ tbnz(disp_hdr, exact_log2(markOopDesc::monitor_value), object_has_monitor);
  
!     // Set displaced_header to be (markOop of object | UNLOCK_VALUE).
!     __ orr(disp_hdr, disp_hdr, markOopDesc::unlocked_value);
  
      // Load Compare Value application register.
  
      // Initialize the box. (Must happen before we update the object mark!)
!     __ str(disp_hdr, Address(box, BasicLock::displaced_header_offset_in_bytes()));
  
!     // Compare object markOop with mark and if equal exchange scratch1
!     // with object markOop.
      if (UseLSE) {
!       __ mov(tmp, disp_hdr);
!       __ casal(Assembler::xword, tmp, box, oop);
        __ cmp(tmp, disp_hdr);
        __ br(Assembler::EQ, cont);
      } else {
        Label retry_load;
        if ((VM_Version::features() & VM_Version::CPU_STXR_PREFETCH))
          __ prfm(Address(oop), PSTL1STRM);
        __ bind(retry_load);
!       __ ldaxr(tmp, oop);
        __ cmp(tmp, disp_hdr);
        __ br(Assembler::NE, cas_failed);
        // use stlxr to ensure update is immediately visible
!       __ stlxr(tmp, box, oop);
!       __ cbzw(tmp, cont);
        __ b(retry_load);
      }
  
      assert(oopDesc::mark_offset_in_bytes() == 0, "offset of _mark is not 0");
  
--- 3418,3454 ----
      }
  
      // Handle existing monitor
      __ tbnz(disp_hdr, exact_log2(markOopDesc::monitor_value), object_has_monitor);
  
!     // Set tmp to be (markOop of object | UNLOCK_VALUE).
!     __ orr(tmp, disp_hdr, markOopDesc::unlocked_value);
  
      // Load Compare Value application register.
  
      // Initialize the box. (Must happen before we update the object mark!)
!     __ str(tmp, Address(box, BasicLock::displaced_header_offset_in_bytes()));
  
!     // Compare object markOop with an unlocked value (tmp) and if
!     // equal exchange the stack address of our box with object markOop.
!     // On failure disp_hdr contains the possibly locked markOop.
      if (UseLSE) {
!       __ mov(disp_hdr, tmp);
!       __ casal(Assembler::xword, disp_hdr, box, oop);  // Updates disp_hdr
        __ cmp(tmp, disp_hdr);
        __ br(Assembler::EQ, cont);
      } else {
        Label retry_load;
        if ((VM_Version::features() & VM_Version::CPU_STXR_PREFETCH))
          __ prfm(Address(oop), PSTL1STRM);
        __ bind(retry_load);
!       __ ldaxr(disp_hdr, oop);
        __ cmp(tmp, disp_hdr);
        __ br(Assembler::NE, cas_failed);
        // use stlxr to ensure update is immediately visible
!       __ stlxr(disp_hdr, box, oop);
!       __ cbzw(disp_hdr, cont);
        __ b(retry_load);
      }
  
      assert(oopDesc::mark_offset_in_bytes() == 0, "offset of _mark is not 0");