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6912064: type profiles need to be exploited more for dynamic language support

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Reviewed-by: kvn
This commit is contained in:
John R Rose 2010-08-20 23:40:30 -07:00
parent a54b1ff70e
commit c7e50e8305
8 changed files with 204 additions and 64 deletions
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167
hotspot/src/share/vm/opto/graphKit.cpp
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@ -2451,11 +2451,79 @@ Node* GraphKit::type_check_receiver(Node* receiver, ciKlass* klass,
}
//------------------------------seems_never_null-------------------------------
// Use null_seen information if it is available from the profile.
// If we see an unexpected null at a type check we record it and force a
// recompile; the offending check will be recompiled to handle NULLs.
// If we see several offending BCIs, then all checks in the
// method will be recompiled.
bool GraphKit::seems_never_null(Node* obj, ciProfileData* data) {
if (UncommonNullCast // Cutout for this technique
&& obj != null() // And not the -Xcomp stupid case?
&& !too_many_traps(Deoptimization::Reason_null_check)
) {
if (data == NULL)
// Edge case: no mature data. Be optimistic here.
return true;
// If the profile has not seen a null, assume it won't happen.
assert(java_bc() == Bytecodes::_checkcast ||
java_bc() == Bytecodes::_instanceof ||
java_bc() == Bytecodes::_aastore, "MDO must collect null_seen bit here");
return !data->as_BitData()->null_seen();
}
return false;
}
//------------------------maybe_cast_profiled_receiver-------------------------
// If the profile has seen exactly one type, narrow to exactly that type.
// Subsequent type checks will always fold up.
Node* GraphKit::maybe_cast_profiled_receiver(Node* not_null_obj,
ciProfileData* data,
ciKlass* require_klass) {
if (!UseTypeProfile || !TypeProfileCasts) return NULL;
if (data == NULL) return NULL;
// Make sure we haven't already deoptimized from this tactic.
if (too_many_traps(Deoptimization::Reason_class_check))
return NULL;
// (No, this isn't a call, but it's enough like a virtual call
// to use the same ciMethod accessor to get the profile info...)
ciCallProfile profile = method()->call_profile_at_bci(bci());
if (profile.count() >= 0 && // no cast failures here
profile.has_receiver(0) &&
profile.morphism() == 1) {
ciKlass* exact_kls = profile.receiver(0);
if (require_klass == NULL ||
static_subtype_check(require_klass, exact_kls) == SSC_always_true) {
// If we narrow the type to match what the type profile sees,
// we can then remove the rest of the cast.
// This is a win, even if the exact_kls is very specific,
// because downstream operations, such as method calls,
// will often benefit from the sharper type.
Node* exact_obj = not_null_obj; // will get updated in place...
Node* slow_ctl = type_check_receiver(exact_obj, exact_kls, 1.0,
&exact_obj);
{ PreserveJVMState pjvms(this);
set_control(slow_ctl);
uncommon_trap(Deoptimization::Reason_class_check,
Deoptimization::Action_maybe_recompile);
}
replace_in_map(not_null_obj, exact_obj);
return exact_obj;
}
// assert(ssc == SSC_always_true)... except maybe the profile lied to us.
}
return NULL;
}
//-------------------------------gen_instanceof--------------------------------
// Generate an instance-of idiom. Used by both the instance-of bytecode
// and the reflective instance-of call.
Node* GraphKit::gen_instanceof( Node *subobj, Node* superklass ) {
C->set_has_split_ifs(true); // Has chance for split-if optimization
Node* GraphKit::gen_instanceof(Node* obj, Node* superklass) {
kill_dead_locals(); // Benefit all the uncommon traps
assert( !stopped(), "dead parse path should be checked in callers" );
assert(!TypePtr::NULL_PTR->higher_equal(_gvn.type(superklass)->is_klassptr()),
"must check for not-null not-dead klass in callers");
@ -2466,9 +2534,16 @@ Node* GraphKit::gen_instanceof( Node *subobj, Node* superklass ) {
Node* phi = new(C, PATH_LIMIT) PhiNode(region, TypeInt::BOOL);
C->set_has_split_ifs(true); // Has chance for split-if optimization
ciProfileData* data = NULL;
if (java_bc() == Bytecodes::_instanceof) { // Only for the bytecode
data = method()->method_data()->bci_to_data(bci());
}
bool never_see_null = (ProfileDynamicTypes // aggressive use of profile
&& seems_never_null(obj, data));
// Null check; get casted pointer; set region slot 3
Node* null_ctl = top();
Node* not_null_obj = null_check_oop(subobj, &null_ctl);
Node* not_null_obj = null_check_oop(obj, &null_ctl, never_see_null);
// If not_null_obj is dead, only null-path is taken
if (stopped()) { // Doing instance-of on a NULL?
@ -2477,6 +2552,23 @@ Node* GraphKit::gen_instanceof( Node *subobj, Node* superklass ) {
}
region->init_req(_null_path, null_ctl);
phi ->init_req(_null_path, intcon(0)); // Set null path value
if (null_ctl == top()) {
// Do this eagerly, so that pattern matches like is_diamond_phi
// will work even during parsing.
assert(_null_path == PATH_LIMIT-1, "delete last");
region->del_req(_null_path);
phi ->del_req(_null_path);
}
if (ProfileDynamicTypes && data != NULL) {
Node* cast_obj = maybe_cast_profiled_receiver(not_null_obj, data, NULL);
if (stopped()) { // Profile disagrees with this path.
set_control(null_ctl); // Null is the only remaining possibility.
return intcon(0);
}
if (cast_obj != NULL)
not_null_obj = cast_obj;
}
// Load the object's klass
Node* obj_klass = load_object_klass(not_null_obj);
@ -2546,20 +2638,8 @@ Node* GraphKit::gen_checkcast(Node *obj, Node* superklass,
C->set_has_split_ifs(true); // Has chance for split-if optimization
// Use null-cast information if it is available
bool never_see_null = false;
// If we see an unexpected null at a check-cast we record it and force a
// recompile; the offending check-cast will be compiled to handle NULLs.
// If we see several offending BCIs, then all checkcasts in the
// method will be compiled to handle NULLs.
if (UncommonNullCast // Cutout for this technique
&& failure_control == NULL // regular case
&& obj != null() // And not the -Xcomp stupid case?
&& !too_many_traps(Deoptimization::Reason_null_check)) {
// Finally, check the "null_seen" bit from the interpreter.
if (data == NULL || !data->as_BitData()->null_seen()) {
never_see_null = true;
}
}
bool never_see_null = ((failure_control == NULL) // regular case only
&& seems_never_null(obj, data));
// Null check; get casted pointer; set region slot 3
Node* null_ctl = top();
@ -2572,47 +2652,26 @@ Node* GraphKit::gen_checkcast(Node *obj, Node* superklass,
}
region->init_req(_null_path, null_ctl);
phi ->init_req(_null_path, null()); // Set null path value
if (null_ctl == top()) {
// Do this eagerly, so that pattern matches like is_diamond_phi
// will work even during parsing.
assert(_null_path == PATH_LIMIT-1, "delete last");
region->del_req(_null_path);
phi ->del_req(_null_path);
}
Node* cast_obj = NULL; // the casted version of the object
// If the profile has seen exactly one type, narrow to that type.
// (The subsequent subtype check will always fold up.)
if (UseTypeProfile && TypeProfileCasts && data != NULL &&
Node* cast_obj = NULL;
if (data != NULL &&
// Counter has never been decremented (due to cast failure).
// ...This is a reasonable thing to expect. It is true of
// all casts inserted by javac to implement generic types.
data->as_CounterData()->count() >= 0 &&
!too_many_traps(Deoptimization::Reason_class_check)) {
// (No, this isn't a call, but it's enough like a virtual call
// to use the same ciMethod accessor to get the profile info...)
ciCallProfile profile = method()->call_profile_at_bci(bci());
if (profile.count() >= 0 && // no cast failures here
profile.has_receiver(0) &&
profile.morphism() == 1) {
ciKlass* exact_kls = profile.receiver(0);
int ssc = static_subtype_check(tk->klass(), exact_kls);
if (ssc == SSC_always_true) {
// If we narrow the type to match what the type profile sees,
// we can then remove the rest of the cast.
// This is a win, even if the exact_kls is very specific,
// because downstream operations, such as method calls,
// will often benefit from the sharper type.
Node* exact_obj = not_null_obj; // will get updated in place...
Node* slow_ctl = type_check_receiver(exact_obj, exact_kls, 1.0,
&exact_obj);
{ PreserveJVMState pjvms(this);
set_control(slow_ctl);
uncommon_trap(Deoptimization::Reason_class_check,
Deoptimization::Action_maybe_recompile);
}
if (failure_control != NULL) // failure is now impossible
(*failure_control) = top();
replace_in_map(not_null_obj, exact_obj);
// adjust the type of the phi to the exact klass:
phi->raise_bottom_type(_gvn.type(exact_obj)->meet(TypePtr::NULL_PTR));
cast_obj = exact_obj;
}
// assert(cast_obj != NULL)... except maybe the profile lied to us.
data->as_CounterData()->count() >= 0) {
cast_obj = maybe_cast_profiled_receiver(not_null_obj, data, tk->klass());
if (cast_obj != NULL) {
if (failure_control != NULL) // failure is now impossible
(*failure_control) = top();
// adjust the type of the phi to the exact klass:
phi->raise_bottom_type(_gvn.type(cast_obj)->meet(TypePtr::NULL_PTR));
}
}