src/cpu/aarch64/vm/macroAssembler_aarch64.cpp

rev 12203 : [mq]: casfixes.patch

@@ -2200,26 +2200,36 @@
 void MacroAssembler::cmpxchg_oop_shenandoah(Register addr, Register expected,
                                             Register new_val,
                                             enum operand_size size,
                                             bool acquire, bool release,
                                             bool weak,
-                                            Register res, Register tmp2) {
+                                            Register result, Register tmp2) {
   assert(UseShenandoahGC, "only for shenandoah");
-  Register result = res;
-  if (result == noreg) result = rscratch1;
+  bool is_cae = (result != noreg);
+  bool is_narrow = (size == word);
+
+  if (! is_cae) result = rscratch1;
 
   assert_different_registers(addr, expected, new_val, result, tmp2);
 
+  if (ShenandoahStoreCheck) {
+    if (is_narrow) {
+      decode_heap_oop(tmp2, new_val);
+      shenandoah_store_check(addr, tmp2);
+    } else {
+      shenandoah_store_check(addr, new_val);
+    }
+  }
   Label retry, done, fail;
 
   // CAS, using LL/SC pair.
   bind(retry);
   load_exclusive(result, addr, size, acquire);
-  if (size == xword) {
-    cmp(result, expected);
-  } else {
+  if (is_narrow) {
     cmpw(result, expected);
+  } else {
+    cmp(result, expected);
   }
   br(Assembler::NE, fail);
   store_exclusive(tmp2, new_val, addr, size, release);
   if (weak) {
     cmpw(tmp2, 0u); // If the store fails, return NE to our caller

@@ -2231,22 +2241,22 @@
   bind(fail);
   // Check if rb(expected)==rb(result)
   // Shuffle registers so that we have memory value ready for next expected.
   mov(tmp2, expected);
   mov(expected, result);
-  if (size == word) {
+  if (is_narrow) {
     decode_heap_oop(result, result);
     decode_heap_oop(tmp2, tmp2);
   }
   oopDesc::bs()->interpreter_read_barrier(this, result);
   oopDesc::bs()->interpreter_read_barrier(this, tmp2);
   cmp(result, tmp2);
   // Retry with expected now being the value we just loaded from addr.
   br(Assembler::EQ, retry);
-  if (size == word && res != noreg) {
+  if (is_narrow && is_cae) {
     // For cmp-and-exchange and narrow oops, we need to restore
-    // the compressed old-value.
+    // the compressed old-value. We moved it to 'expected' a few lines up.
     mov(result, expected);
   }
   bind(done);
 }