src/hotspot/cpu/aarch64/macroAssembler_aarch64.cpp

*** 2365,2401 ****
                               enum operand_size size,
                               bool acquire, bool release,
                               bool weak,
                               Register result) {
    if (result == noreg)  result = rscratch1;
    if (UseLSE) {
      mov(result, expected);
      lse_cas(result, new_val, addr, size, acquire, release, /*not_pair*/ true);
!     cmp(result, expected);
    } else {
-     BLOCK_COMMENT("cmpxchg {");
      Label retry_load, done;
      if ((VM_Version::features() & VM_Version::CPU_STXR_PREFETCH))
        prfm(Address(addr), PSTL1STRM);
      bind(retry_load);
      load_exclusive(result, addr, size, acquire);
!     if (size == xword)
!       cmp(result, expected);
!     else
!       cmpw(result, expected);
      br(Assembler::NE, done);
      store_exclusive(rscratch1, new_val, addr, size, release);
      if (weak) {
        cmpw(rscratch1, 0u);  // If the store fails, return NE to our caller.
      } else {
        cbnzw(rscratch1, retry_load);
      }
      bind(done);
      BLOCK_COMMENT("} cmpxchg");
    }
  }
  
  static bool different(Register a, RegisterOrConstant b, Register c) {
    if (b.is_constant())
      return a != c;
    else
      return a != b.as_register() && a != c && b.as_register() != c;
--- 2365,2416 ----
                               enum operand_size size,
                               bool acquire, bool release,
                               bool weak,
                               Register result) {
    if (result == noreg)  result = rscratch1;
+   BLOCK_COMMENT("cmpxchg {");
    if (UseLSE) {
      mov(result, expected);
      lse_cas(result, new_val, addr, size, acquire, release, /*not_pair*/ true);
!     compare_eq(result, expected, size);
    } else {
      Label retry_load, done;
      if ((VM_Version::features() & VM_Version::CPU_STXR_PREFETCH))
        prfm(Address(addr), PSTL1STRM);
      bind(retry_load);
      load_exclusive(result, addr, size, acquire);
!     compare_eq(result, expected, size);
      br(Assembler::NE, done);
      store_exclusive(rscratch1, new_val, addr, size, release);
      if (weak) {
        cmpw(rscratch1, 0u);  // If the store fails, return NE to our caller.
      } else {
        cbnzw(rscratch1, retry_load);
      }
      bind(done);
+   }
    BLOCK_COMMENT("} cmpxchg");
+ }
+ 
+ // A generic comparison. Only compares for equality, clobbers rscratch1.
+ void MacroAssembler::compare_eq(Register rm, Register rn, enum operand_size size) {
+   if (size == xword) {
+     cmp(rm, rn);
+   } else if (size == word) {
+     cmpw(rm, rn);
+   } else if (size == halfword) {
+     eorw(rscratch1, rm, rn);
+     ands(zr, rscratch1, 0xffff);
+   } else if (size == byte) {
+     eorw(rscratch1, rm, rn);
+     ands(zr, rscratch1, 0xff);
+   } else {
+     ShouldNotReachHere();
    }
  }
  
+ 
  static bool different(Register a, RegisterOrConstant b, Register c) {
    if (b.is_constant())
      return a != c;
    else
      return a != b.as_register() && a != c && b.as_register() != c;