src/hotspot/cpu/x86/macroAssembler_x86.cpp

@@ -4154,16 +4154,29 @@
  }
  
  // Preserves the contents of address, destroys the contents length_in_bytes and temp.
  void MacroAssembler::zero_memory(Register address, Register length_in_bytes, int offset_in_bytes, Register temp) {
    assert(address != length_in_bytes && address != temp && temp != length_in_bytes, "registers must be different");
-   assert((offset_in_bytes & (BytesPerWord - 1)) == 0, "offset must be a multiple of BytesPerWord");
+   assert((offset_in_bytes & (BytesPerInt - 1)) == 0, "offset must be a multiple of BytesPerInt");
    Label done;
  
    testptr(length_in_bytes, length_in_bytes);
    jcc(Assembler::zero, done);
  
+   // Emit single 32bit store to clear leading bytes, if necessary.
+   xorptr(temp, temp);    // use _zero reg to clear memory (shorter code)
+ #ifdef _LP64
+   if (!is_aligned(offset_in_bytes, BytesPerWord)) {
+     movl(Address(address, offset_in_bytes), temp);
+     offset_in_bytes += BytesPerInt;
+     decrement(length_in_bytes, BytesPerInt);
+   }
+   assert((offset_in_bytes & (BytesPerWord - 1)) == 0, "offset must be a multiple of BytesPerWord");
+   testptr(length_in_bytes, length_in_bytes);
+   jcc(Assembler::zero, done);
+ #endif
+ 
    // initialize topmost word, divide index by 2, check if odd and test if zero
    // note: for the remaining code to work, index must be a multiple of BytesPerWord
  #ifdef ASSERT
    {
      Label L;

@@ -4172,11 +4185,10 @@
      stop("length must be a multiple of BytesPerWord");
      bind(L);
    }
  #endif
    Register index = length_in_bytes;
-   xorptr(temp, temp);    // use _zero reg to clear memory (shorter code)
    if (UseIncDec) {
      shrptr(index, 3);  // divide by 8/16 and set carry flag if bit 2 was set
    } else {
      shrptr(index, 2);  // use 2 instructions to avoid partial flag stall
      shrptr(index, 1);

@@ -5223,32 +5235,94 @@
    movptr(holder, Address(method, Method::const_offset()));                      // ConstMethod*
    movptr(holder, Address(holder, ConstMethod::constants_offset()));             // ConstantPool*
    movptr(holder, Address(holder, ConstantPool::pool_holder_offset()));          // InstanceKlass*
  }
  
+ #ifdef _LP64
+ void MacroAssembler::load_nklass(Register dst, Register src) {
+   assert(UseCompressedClassPointers, "expect compressed class pointers");
+ 
+   if (!UseCompactObjectHeaders) {
+     movl(dst, Address(src, oopDesc::klass_offset_in_bytes()));
+     return;
+   }
+ 
+   Label fast;
+   movq(dst, Address(src, oopDesc::mark_offset_in_bytes()));
+   testb(dst, markWord::monitor_value);
+   jccb(Assembler::zero, fast);
+ 
+   // Fetch displaced header
+   movq(dst, Address(dst, OM_OFFSET_NO_MONITOR_VALUE_TAG(header)));
+ 
+   bind(fast);
+   shrq(dst, markWord::klass_shift);
+ }
+ #endif
+ 
  void MacroAssembler::load_klass(Register dst, Register src, Register tmp) {
    assert_different_registers(src, tmp);
    assert_different_registers(dst, tmp);
  #ifdef _LP64
    if (UseCompressedClassPointers) {
-     movl(dst, Address(src, oopDesc::klass_offset_in_bytes()));
+     load_nklass(dst, src);
      decode_klass_not_null(dst, tmp);
    } else
  #endif
      movptr(dst, Address(src, oopDesc::klass_offset_in_bytes()));
  }
  
  void MacroAssembler::store_klass(Register dst, Register src, Register tmp) {
+   assert(!UseCompactObjectHeaders, "not with compact headers");
    assert_different_registers(src, tmp);
    assert_different_registers(dst, tmp);
  #ifdef _LP64
    if (UseCompressedClassPointers) {
      encode_klass_not_null(src, tmp);
      movl(Address(dst, oopDesc::klass_offset_in_bytes()), src);
    } else
  #endif
-     movptr(Address(dst, oopDesc::klass_offset_in_bytes()), src);
+    movptr(Address(dst, oopDesc::klass_offset_in_bytes()), src);
+ }
+ 
+ void MacroAssembler::cmp_klass(Register klass, Register obj, Register tmp) {
+ #ifdef _LP64
+   if (UseCompactObjectHeaders) {
+     // NOTE: We need to deal with possible ObjectMonitor in object header.
+     // Eventually we might be able to do simple movl & cmpl like in
+     // the CCP path below.
+     load_nklass(tmp, obj);
+     cmpl(klass, tmp);
+   } else if (UseCompressedClassPointers) {
+     cmpl(klass, Address(obj, oopDesc::klass_offset_in_bytes()));
+   } else
+ #endif
+   {
+     cmpptr(klass, Address(obj, oopDesc::klass_offset_in_bytes()));
+   }
+ }
+ 
+ void MacroAssembler::cmp_klass(Register src, Register dst, Register tmp1, Register tmp2) {
+ #ifdef _LP64
+   if (UseCompactObjectHeaders) {
+     // NOTE: We need to deal with possible ObjectMonitor in object header.
+     // Eventually we might be able to do simple movl & cmpl like in
+     // the CCP path below.
+     assert(tmp2 != noreg, "need tmp2");
+     assert_different_registers(src, dst, tmp1, tmp2);
+     load_nklass(tmp1, src);
+     load_nklass(tmp2, dst);
+     cmpl(tmp1, tmp2);
+   } else if (UseCompressedClassPointers) {
+     movl(tmp1, Address(src, oopDesc::klass_offset_in_bytes()));
+     cmpl(tmp1, Address(dst, oopDesc::klass_offset_in_bytes()));
+   } else
+ #endif
+   {
+     movptr(tmp1, Address(src, oopDesc::klass_offset_in_bytes()));
+     cmpptr(tmp1, Address(dst, oopDesc::klass_offset_in_bytes()));
+   }
  }
  
  void MacroAssembler::access_load_at(BasicType type, DecoratorSet decorators, Register dst, Address src,
                                      Register tmp1, Register thread_tmp) {
    BarrierSetAssembler* bs = BarrierSet::barrier_set()->barrier_set_assembler();