archive/jdk
1
0
Fork 0
mirror of https://github.com/openjdk/jdk.git synced 2025-09-23 04:24:49 +02:00
Code Issues Projects Releases Packages Wiki Activity Actions

6730716: nulls from two unrelated classes compare not equal

Browse source 
Check for not-nullness after proving that types are unrelated

Reviewed-by: kvn, never
This commit is contained in:
Chuck Rasbold 2008-08-19 07:25:02 -07:00
parent 45f8e241e3
commit ae4e755124
1 changed files with 34 additions and 12 deletions
Download patch file Download diff file Expand all files Collapse all files

46
hotspot/src/share/vm/opto/subnode.cpp
View file

@ -633,20 +633,31 @@ const Type *CmpPNode::sub( const Type *t1, const Type *t2 ) const {
kps != 1 && // both or neither are klass pointers
!klass0->is_interface() && // do not trust interfaces
!klass1->is_interface()) {
bool unrelated_classes = false;
// See if neither subclasses the other, or if the class on top
// is precise. In either of these cases, the compare must fail.
// is precise. In either of these cases, the compare is known
// to fail if at least one of the pointers is provably not null.
if (klass0->equals(klass1) || // if types are unequal but klasses are
!klass0->is_java_klass() || // types not part of Java language?
!klass1->is_java_klass()) { // types not part of Java language?
// Do nothing; we know nothing for imprecise types
} else if (klass0->is_subtype_of(klass1)) {
// If klass1's type is PRECISE, then we can fail.
if (xklass1) return TypeInt::CC_GT;
// If klass1's type is PRECISE, then classes are unrelated.
unrelated_classes = xklass1;
} else if (klass1->is_subtype_of(klass0)) {
// If klass0's type is PRECISE, then we can fail.
if (xklass0) return TypeInt::CC_GT;
// If klass0's type is PRECISE, then classes are unrelated.
unrelated_classes = xklass0;
} else { // Neither subtypes the other
return TypeInt::CC_GT; // ...so always fail
unrelated_classes = true;
}
if (unrelated_classes) {
// The oops classes are known to be unrelated. If the joined PTRs of
// two oops is not Null and not Bottom, then we are sure that one
// of the two oops is non-null, and the comparison will always fail.
TypePtr::PTR jp = r0->join_ptr(r1->_ptr);
if (jp != TypePtr::Null && jp != TypePtr::BotPTR) {
return TypeInt::CC_GT;
}
}
}
}
@ -777,20 +788,31 @@ const Type *CmpNNode::sub( const Type *t1, const Type *t2 ) const {
kps != 1 && // both or neither are klass pointers
!klass0->is_interface() && // do not trust interfaces
!klass1->is_interface()) {
bool unrelated_classes = false;
// See if neither subclasses the other, or if the class on top
// is precise. In either of these cases, the compare must fail.
// is precise. In either of these cases, the compare is known
// to fail if at least one of the pointers is provably not null.
if (klass0->equals(klass1) || // if types are unequal but klasses are
!klass0->is_java_klass() || // types not part of Java language?
!klass1->is_java_klass()) { // types not part of Java language?
// Do nothing; we know nothing for imprecise types
} else if (klass0->is_subtype_of(klass1)) {
// If klass1's type is PRECISE, then we can fail.
if (xklass1) return TypeInt::CC_GT;
// If klass1's type is PRECISE, then classes are unrelated.
unrelated_classes = xklass1;
} else if (klass1->is_subtype_of(klass0)) {
// If klass0's type is PRECISE, then we can fail.
if (xklass0) return TypeInt::CC_GT;
// If klass0's type is PRECISE, then classes are unrelated.
unrelated_classes = xklass0;
} else { // Neither subtypes the other
return TypeInt::CC_GT; // ...so always fail
unrelated_classes = true;
}
if (unrelated_classes) {
// The oops classes are known to be unrelated. If the joined PTRs of
// two oops is not Null and not Bottom, then we are sure that one
// of the two oops is non-null, and the comparison will always fail.
TypePtr::PTR jp = r0->join_ptr(r1->_ptr);
if (jp != TypePtr::Null && jp != TypePtr::BotPTR) {
return TypeInt::CC_GT;
}
}
}
}