--- a/hotspot/src/share/vm/opto/memnode.cpp Wed Dec 05 09:00:00 2007 -0800
+++ b/hotspot/src/share/vm/opto/memnode.cpp Wed Dec 05 09:01:00 2007 -0800
@@ -634,6 +634,46 @@
Node* MemNode::can_see_stored_value(Node* st, PhaseTransform* phase) const {
Node* ld_adr = in(MemNode::Address);
+ const TypeInstPtr* tp = phase->type(ld_adr)->isa_instptr();
+ Compile::AliasType* atp = tp != NULL ? phase->C->alias_type(tp) : NULL;
+ if (EliminateAutoBox && atp != NULL && atp->index() >= Compile::AliasIdxRaw &&
+ atp->field() != NULL && !atp->field()->is_volatile()) {
+ uint alias_idx = atp->index();
+ bool final = atp->field()->is_final();
+ Node* result = NULL;
+ Node* current = st;
+ // Skip through chains of MemBarNodes checking the MergeMems for
+ // new states for the slice of this load. Stop once any other
+ // kind of node is encountered. Loads from final memory can skip
+ // through any kind of MemBar but normal loads shouldn't skip
+ // through MemBarAcquire since the could allow them to move out of
+ // a synchronized region.
+ while (current->is_Proj()) {
+ int opc = current->in(0)->Opcode();
+ if ((final && opc == Op_MemBarAcquire) ||
+ opc == Op_MemBarRelease || opc == Op_MemBarCPUOrder) {
+ Node* mem = current->in(0)->in(TypeFunc::Memory);
+ if (mem->is_MergeMem()) {
+ MergeMemNode* merge = mem->as_MergeMem();
+ Node* new_st = merge->memory_at(alias_idx);
+ if (new_st == merge->base_memory()) {
+ // Keep searching
+ current = merge->base_memory();
+ continue;
+ }
+ // Save the new memory state for the slice and fall through
+ // to exit.
+ result = new_st;
+ }
+ }
+ break;
+ }
+ if (result != NULL) {
+ st = result;
+ }
+ }
+
+
// Loop around twice in the case Load -> Initialize -> Store.
// (See PhaseIterGVN::add_users_to_worklist, which knows about this case.)
for (int trip = 0; trip <= 1; trip++) {
@@ -723,6 +763,168 @@
return this;
}
+
+// Returns true if the AliasType refers to the field that holds the
+// cached box array. Currently only handles the IntegerCache case.
+static bool is_autobox_cache(Compile::AliasType* atp) {
+ if (atp != NULL && atp->field() != NULL) {
+ ciField* field = atp->field();
+ ciSymbol* klass = field->holder()->name();
+ if (field->name() == ciSymbol::cache_field_name() &&
+ field->holder()->uses_default_loader() &&
+ klass == ciSymbol::java_lang_Integer_IntegerCache()) {
+ return true;
+ }
+ }
+ return false;
+}
+
+// Fetch the base value in the autobox array
+static bool fetch_autobox_base(Compile::AliasType* atp, int& cache_offset) {
+ if (atp != NULL && atp->field() != NULL) {
+ ciField* field = atp->field();
+ ciSymbol* klass = field->holder()->name();
+ if (field->name() == ciSymbol::cache_field_name() &&
+ field->holder()->uses_default_loader() &&
+ klass == ciSymbol::java_lang_Integer_IntegerCache()) {
+ assert(field->is_constant(), "what?");
+ ciObjArray* array = field->constant_value().as_object()->as_obj_array();
+ // Fetch the box object at the base of the array and get its value
+ ciInstance* box = array->obj_at(0)->as_instance();
+ ciInstanceKlass* ik = box->klass()->as_instance_klass();
+ if (ik->nof_nonstatic_fields() == 1) {
+ // This should be true nonstatic_field_at requires calling
+ // nof_nonstatic_fields so check it anyway
+ ciConstant c = box->field_value(ik->nonstatic_field_at(0));
+ cache_offset = c.as_int();
+ }
+ return true;
+ }
+ }
+ return false;
+}
+
+// Returns true if the AliasType refers to the value field of an
+// autobox object. Currently only handles Integer.
+static bool is_autobox_object(Compile::AliasType* atp) {
+ if (atp != NULL && atp->field() != NULL) {
+ ciField* field = atp->field();
+ ciSymbol* klass = field->holder()->name();
+ if (field->name() == ciSymbol::value_name() &&
+ field->holder()->uses_default_loader() &&
+ klass == ciSymbol::java_lang_Integer()) {
+ return true;
+ }
+ }
+ return false;
+}
+
+
+// We're loading from an object which has autobox behaviour.
+// If this object is result of a valueOf call we'll have a phi
+// merging a newly allocated object and a load from the cache.
+// We want to replace this load with the original incoming
+// argument to the valueOf call.
+Node* LoadNode::eliminate_autobox(PhaseGVN* phase) {
+ Node* base = in(Address)->in(AddPNode::Base);
+ if (base->is_Phi() && base->req() == 3) {
+ AllocateNode* allocation = NULL;
+ int allocation_index = -1;
+ int load_index = -1;
+ for (uint i = 1; i < base->req(); i++) {
+ allocation = AllocateNode::Ideal_allocation(base->in(i), phase);
+ if (allocation != NULL) {
+ allocation_index = i;
+ load_index = 3 - allocation_index;
+ break;
+ }
+ }
+ LoadNode* load = NULL;
+ if (allocation != NULL && base->in(load_index)->is_Load()) {
+ load = base->in(load_index)->as_Load();
+ }
+ if (load != NULL && in(Memory)->is_Phi() && in(Memory)->in(0) == base->in(0)) {
+ // Push the loads from the phi that comes from valueOf up
+ // through it to allow elimination of the loads and the recovery
+ // of the original value.
+ Node* mem_phi = in(Memory);
+ Node* offset = in(Address)->in(AddPNode::Offset);
+
+ Node* in1 = clone();
+ Node* in1_addr = in1->in(Address)->clone();
+ in1_addr->set_req(AddPNode::Base, base->in(allocation_index));
+ in1_addr->set_req(AddPNode::Address, base->in(allocation_index));
+ in1_addr->set_req(AddPNode::Offset, offset);
+ in1->set_req(0, base->in(allocation_index));
+ in1->set_req(Address, in1_addr);
+ in1->set_req(Memory, mem_phi->in(allocation_index));
+
+ Node* in2 = clone();
+ Node* in2_addr = in2->in(Address)->clone();
+ in2_addr->set_req(AddPNode::Base, base->in(load_index));
+ in2_addr->set_req(AddPNode::Address, base->in(load_index));
+ in2_addr->set_req(AddPNode::Offset, offset);
+ in2->set_req(0, base->in(load_index));
+ in2->set_req(Address, in2_addr);
+ in2->set_req(Memory, mem_phi->in(load_index));
+
+ in1_addr = phase->transform(in1_addr);
+ in1 = phase->transform(in1);
+ in2_addr = phase->transform(in2_addr);
+ in2 = phase->transform(in2);
+
+ PhiNode* result = PhiNode::make_blank(base->in(0), this);
+ result->set_req(allocation_index, in1);
+ result->set_req(load_index, in2);
+ return result;
+ }
+ } else if (base->is_Load()) {
+ // Eliminate the load of Integer.value for integers from the cache
+ // array by deriving the value from the index into the array.
+ // Capture the offset of the load and then reverse the computation.
+ Node* load_base = base->in(Address)->in(AddPNode::Base);
+ if (load_base != NULL) {
+ Compile::AliasType* atp = phase->C->alias_type(load_base->adr_type());
+ intptr_t cache_offset;
+ int shift = -1;
+ Node* cache = NULL;
+ if (is_autobox_cache(atp)) {
+ shift = exact_log2(type2aelembytes[T_OBJECT]);
+ cache = AddPNode::Ideal_base_and_offset(load_base->in(Address), phase, cache_offset);
+ }
+ if (cache != NULL && base->in(Address)->is_AddP()) {
+ Node* elements[4];
+ int count = base->in(Address)->as_AddP()->unpack_offsets(elements, ARRAY_SIZE(elements));
+ int cache_low;
+ if (count > 0 && fetch_autobox_base(atp, cache_low)) {
+ int offset = arrayOopDesc::base_offset_in_bytes(memory_type()) - (cache_low << shift);
+ // Add up all the offsets making of the address of the load
+ Node* result = elements[0];
+ for (int i = 1; i < count; i++) {
+ result = phase->transform(new (phase->C, 3) AddXNode(result, elements[i]));
+ }
+ // Remove the constant offset from the address and then
+ // remove the scaling of the offset to recover the original index.
+ result = phase->transform(new (phase->C, 3) AddXNode(result, phase->MakeConX(-offset)));
+ if (result->Opcode() == Op_LShiftX && result->in(2) == phase->intcon(shift)) {
+ // Peel the shift off directly but wrap it in a dummy node
+ // since Ideal can't return existing nodes
+ result = new (phase->C, 3) RShiftXNode(result->in(1), phase->intcon(0));
+ } else {
+ result = new (phase->C, 3) RShiftXNode(result, phase->intcon(shift));
+ }
+#ifdef _LP64
+ result = new (phase->C, 2) ConvL2INode(phase->transform(result));
+#endif
+ return result;
+ }
+ }
+ }
+ }
+ return NULL;
+}
+
+
//------------------------------Ideal------------------------------------------
// If the load is from Field memory and the pointer is non-null, we can
// zero out the control input.
@@ -755,6 +957,17 @@
}
}
+ if (EliminateAutoBox && can_reshape && in(Address)->is_AddP()) {
+ Node* base = in(Address)->in(AddPNode::Base);
+ if (base != NULL) {
+ Compile::AliasType* atp = phase->C->alias_type(adr_type());
+ if (is_autobox_object(atp)) {
+ Node* result = eliminate_autobox(phase);
+ if (result != NULL) return result;
+ }
+ }
+ }
+
// Check for prior store with a different base or offset; make Load
// independent. Skip through any number of them. Bail out if the stores
// are in an endless dead cycle and report no progress. This is a key
@@ -858,6 +1071,17 @@
// This can happen if a interface-typed array narrows to a class type.
jt = _type;
}
+
+ if (EliminateAutoBox) {
+ // The pointers in the autobox arrays are always non-null
+ Node* base = in(Address)->in(AddPNode::Base);
+ if (base != NULL) {
+ Compile::AliasType* atp = phase->C->alias_type(base->adr_type());
+ if (is_autobox_cache(atp)) {
+ return jt->join(TypePtr::NOTNULL)->is_ptr();
+ }
+ }
+ }
return jt;
}
}