src/hotspot/share/opto/compile.cpp

*** 4505,4514 ****
--- 4505,4565 ----
      igvn.check_no_speculative_types();
  #endif
    }
  }
  
+ Node* Compile::load_is_value_bit(PhaseGVN* phase, Node* oop) {
+   // Load the klass pointer and check if it's odd, i.e., if it defines a value type
+   // is_value = (klass & oop_metadata_odd_mask) >> LogKlassAlignmentInBytes
+   Node* k_adr = phase->transform(new AddPNode(oop, oop, phase->MakeConX(oopDesc::klass_offset_in_bytes())));
+   Node* klass = NULL;
+   if (UseCompressedClassPointers) {
+     klass = phase->transform(new LoadNKlassNode(NULL, immutable_memory(), k_adr, TypeInstPtr::KLASS, TypeKlassPtr::OBJECT->make_narrowklass(), MemNode::unordered));
+   } else {
+     klass = phase->transform(new LoadKlassNode(NULL, immutable_memory(), k_adr, TypeInstPtr::KLASS, TypeKlassPtr::OBJECT, MemNode::unordered));
+   }
+   const int mask = Universe::oop_metadata_odd_mask();
+   Node* is_value = phase->transform(new CastP2XNode(NULL, klass));
+   is_value = phase->transform(new AndXNode(is_value, phase->MakeConX(mask)));
+   // Check if a shift is required for perturbation to affect aligned bits of oop
+   if (mask == KlassPtrEvenOddMask && ObjectAlignmentInBytes <= KlassAlignmentInBytes) {
+     assert((mask >> LogKlassAlignmentInBytes) == 1, "invalid shift");
+     is_value = phase->transform(new URShiftXNode(is_value, phase->intcon(LogKlassAlignmentInBytes)));
+   } else {
+     assert(mask < ObjectAlignmentInBytes, "invalid mask");
+   }
+   return is_value;
+ }
+ 
+ Node* Compile::optimize_acmp(PhaseGVN* phase, Node* a, Node* b) {
+   const TypeInstPtr* ta = phase->type(a)->isa_instptr();
+   const TypeInstPtr* tb = phase->type(b)->isa_instptr();
+   if (!UseNewAcmp || phase->type(a)->is_zero_type() || phase->type(b)->is_zero_type()) {
+     // Use old acmp if new acmp is disabled or degraded to a null check
+     return new CmpPNode(a, b);
+   } else if ((ta != NULL && ta->is_value_based()) || (tb != NULL && tb->is_value_based())) {
+     // We statically know that one operand is a value. Therefore,
+     // new acmp will only return true if both operands are NULL.
+     if ((ta != NULL && !TypePtr::NULL_PTR->higher_equal(ta)) ||
+         (tb != NULL && !TypePtr::NULL_PTR->higher_equal(tb))) {
+       // One operand is never NULL, fold to constant false
+       return new CmpINode(phase->intcon(0), phase->intcon(1));
+     } else {
+       // Check if both operands are null by or'ing the oops
+       a = phase->transform(new CastP2XNode(NULL, a));
+       b = phase->transform(new CastP2XNode(NULL, b));
+       a = phase->transform(new OrXNode(a, b));
+       return new CmpXNode(a, phase->MakeConX(0));
+     }
+   } else if (ta == NULL || !ta->can_be_value_based() || tb == NULL || !tb->can_be_value_based()) {
+     // Use old acmp
+     return new CmpPNode(a, b);
+   }
+   // Use new acmp
+   return NULL;
+ }
+ 
  // Auxiliary method to support randomized stressing/fuzzing.
  //
  // This method can be called the arbitrary number of times, with current count
  // as the argument. The logic allows selecting a single candidate from the
  // running list of candidates as follows: