src/cpu/aarch64/vm/macroAssembler_aarch64.cpp

rev 10243 : 8150394: aarch64: add support for 8.1 LSE CAS instructions
Reviewed-by: aph
Contributed-by: ananth.jasty@caviumnetworks.com, edward.nevill@linaro.org

*** 2068,2078 ****
  void MacroAssembler::cmpxchgptr(Register oldv, Register newv, Register addr, Register tmp,
                                  Label &succeed, Label *fail) {
    // oldv holds comparison value
    // newv holds value to write in exchange
    // addr identifies memory word to compare against/update
!   // tmp returns 0/1 for success/failure
    Label retry_load, nope;
  
    bind(retry_load);
    // flush and load exclusive from the memory location
    // and fail if it is not what we expect
--- 2068,2084 ----
  void MacroAssembler::cmpxchgptr(Register oldv, Register newv, Register addr, Register tmp,
                                  Label &succeed, Label *fail) {
    // oldv holds comparison value
    // newv holds value to write in exchange
    // addr identifies memory word to compare against/update
!   if (UseLSE) {
!     mov(tmp, oldv);
!     casal(Assembler::xword, oldv, newv, addr);
!     cmp(tmp, oldv);
!     br(Assembler::EQ, succeed);
!     membar(AnyAny);
!   } else {
      Label retry_load, nope;
  
      bind(retry_load);
      // flush and load exclusive from the memory location
      // and fail if it is not what we expect
*** 2087,2106 ****
    b(retry_load);
    // if the memory word differs we return it in oldv and signal a fail
    bind(nope);
    membar(AnyAny);
    mov(oldv, tmp);
    if (fail)
      b(*fail);
  }
  
  void MacroAssembler::cmpxchgw(Register oldv, Register newv, Register addr, Register tmp,
                                  Label &succeed, Label *fail) {
    // oldv holds comparison value
    // newv holds value to write in exchange
    // addr identifies memory word to compare against/update
!   // tmp returns 0/1 for success/failure
    Label retry_load, nope;
  
    bind(retry_load);
    // flush and load exclusive from the memory location
    // and fail if it is not what we expect
--- 2093,2119 ----
      b(retry_load);
      // if the memory word differs we return it in oldv and signal a fail
      bind(nope);
      membar(AnyAny);
      mov(oldv, tmp);
+   }
    if (fail)
      b(*fail);
  }
  
  void MacroAssembler::cmpxchgw(Register oldv, Register newv, Register addr, Register tmp,
                                  Label &succeed, Label *fail) {
    // oldv holds comparison value
    // newv holds value to write in exchange
    // addr identifies memory word to compare against/update
!   if (UseLSE) {
!     mov(tmp, oldv);
!     casal(Assembler::word, oldv, newv, addr);
!     cmp(tmp, oldv);
!     br(Assembler::EQ, succeed);
!     membar(AnyAny);
!   } else {
      Label retry_load, nope;
  
      bind(retry_load);
      // flush and load exclusive from the memory location
      // and fail if it is not what we expect
*** 2115,2128 ****
--- 2128,2172 ----
      b(retry_load);
      // if the memory word differs we return it in oldv and signal a fail
      bind(nope);
      membar(AnyAny);
      mov(oldv, tmp);
+   }
    if (fail)
      b(*fail);
  }
  
+ void MacroAssembler::cmpxchg(operand_size sz,
+                              Register oldv, Register newv, Register addr,
+                              bool acquire, bool release,
+                              Register tmp)
+ {
+   // oldv holds comparison value
+   // newv holds value to write in exchange
+   // addr identifies memory word to compare against/update
+   // returns EQ == success, NE == failure
+   if (UseLSE) {
+     mov(tmp, oldv);
+     compare_and_swap(tmp, newv, addr, sz, acquire?1:0, release?1:0);
+     cmp(tmp, oldv);
+   } else {
+     Label retry_load, done;
+ 
+     bind(retry_load);
+     // flush and load exclusive from the memory location
+     // and fail if it is not what we expect
+     cas_load(sz, tmp, addr, acquire?1:0);
+     cmp(tmp, oldv);
+     br(Assembler::NE, done);
+     // if we store+flush with no intervening write tmp wil be zero
+     cas_store(sz, tmp, newv, addr, release?1:0);
+     cbnzw(tmp, retry_load);
+     // if the memory word differs we return it in oldv and signal a fail
+     bind(done);
+   }
+ }
+ 
  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;