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7170463: C2 should recognize "obj.getClass() == A.class" code pattern

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Optimize this code pattern obj.getClass() == A.class.

Reviewed-by: jrose, kvn
This commit is contained in:
Krystal Mok 2012-05-25 07:53:11 -07:00 • committed by Vladimir Kozlov
parent d6d1826ad3
commit a9ea68bd3f
3 changed files with 142 additions and 1 deletions
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66
hotspot/src/share/vm/opto/parse2.cpp
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@ -1233,6 +1233,71 @@ void Parse::adjust_map_after_if(BoolTest::mask btest, Node* c, float prob,
if (!have_con) // remaining adjustments need a con
return;
sharpen_type_after_if(btest, con, tcon, val, tval);
}
static Node* extract_obj_from_klass_load(PhaseGVN* gvn, Node* n) {
Node* ldk;
if (n->is_DecodeN()) {
if (n->in(1)->Opcode() != Op_LoadNKlass) {
return NULL;
} else {
ldk = n->in(1);
}
} else if (n->Opcode() != Op_LoadKlass) {
return NULL;
} else {
ldk = n;
}
assert(ldk != NULL && ldk->is_Load(), "should have found a LoadKlass or LoadNKlass node");
Node* adr = ldk->in(MemNode::Address);
intptr_t off = 0;
Node* obj = AddPNode::Ideal_base_and_offset(adr, gvn, off);
if (obj == NULL || off != oopDesc::klass_offset_in_bytes()) // loading oopDesc::_klass?
return NULL;
const TypePtr* tp = gvn->type(obj)->is_ptr();
if (tp == NULL || !(tp->isa_instptr() || tp->isa_aryptr())) // is obj a Java object ptr?
return NULL;
return obj;
}
void Parse::sharpen_type_after_if(BoolTest::mask btest,
Node* con, const Type* tcon,
Node* val, const Type* tval) {
// Look for opportunities to sharpen the type of a node
// whose klass is compared with a constant klass.
if (btest == BoolTest::eq && tcon->isa_klassptr()) {
Node* obj = extract_obj_from_klass_load(&_gvn, val);
const TypeOopPtr* con_type = tcon->isa_klassptr()->as_instance_type();
if (obj != NULL && (con_type->isa_instptr() || con_type->isa_aryptr())) {
// Found:
// Bool(CmpP(LoadKlass(obj._klass), ConP(Foo.klass)), [eq])
// or the narrowOop equivalent.
const Type* obj_type = _gvn.type(obj);
const TypeOopPtr* tboth = obj_type->join(con_type)->isa_oopptr();
if (tboth != NULL && tboth != obj_type && tboth->higher_equal(obj_type)) {
// obj has to be of the exact type Foo if the CmpP succeeds.
assert(tboth->klass_is_exact(), "klass should be exact");
int obj_in_map = map()->find_edge(obj);
JVMState* jvms = this->jvms();
if (obj_in_map >= 0 &&
(jvms->is_loc(obj_in_map) || jvms->is_stk(obj_in_map))) {
TypeNode* ccast = new (C, 2) CheckCastPPNode(control(), obj, tboth);
const Type* tcc = ccast->as_Type()->type();
assert(tcc != obj_type && tcc->higher_equal(obj_type), "must improve");
// Delay transform() call to allow recovery of pre-cast value
// at the control merge.
_gvn.set_type_bottom(ccast);
record_for_igvn(ccast);
// Here's the payoff.
replace_in_map(obj, ccast);
}
}
}
}
int val_in_map = map()->find_edge(val);
if (val_in_map < 0) return; // replace_in_map would be useless
@ -1265,6 +1330,7 @@ void Parse::adjust_map_after_if(BoolTest::mask btest, Node* c, float prob,
// Exclude tests vs float/double 0 as these could be
// either +0 or -0. Just because you are equal to +0
// doesn't mean you ARE +0!
// Note, following code also replaces Long and Oop values.
if ((!tf || tf->_f != 0.0) &&
(!td || td->_d != 0.0))
cast = con; // Replace non-constant val by con.