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8341178: TypeRawPtr::add_offset may be "miscompiled" due to UB

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Reviewed-by: dlong, kvn
This commit is contained in:
Kim Barrett 2024-10-11 21:11:12 +00:00
parent 1f6bd0c3e5
commit 0a57fe1df6
1 changed files with 13 additions and 7 deletions
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20
src/hotspot/share/opto/type.cpp
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@ -3111,8 +3111,8 @@ const TypeRawPtr *TypeRawPtr::make( enum PTR ptr ) {
return (TypeRawPtr*)(new TypeRawPtr(ptr,nullptr))->hashcons();
}
const TypeRawPtr *TypeRawPtr::make( address bits ) {
assert( bits, "Use TypePtr for null" );
const TypeRawPtr *TypeRawPtr::make(address bits) {
assert(bits != nullptr, "Use TypePtr for null");
return (TypeRawPtr*)(new TypeRawPtr(Constant,bits))->hashcons();
}
@ -3201,15 +3201,21 @@ const TypePtr* TypeRawPtr::add_offset(intptr_t offset) const {
case TypePtr::BotPTR:
case TypePtr::NotNull:
return this;
case TypePtr::Null:
case TypePtr::Constant: {
address bits = _bits+offset;
if ( bits == 0 ) return TypePtr::NULL_PTR;
return make( bits );
uintptr_t bits = (uintptr_t)_bits;
uintptr_t sum = bits + offset;
if (( offset < 0 )
? ( sum > bits ) // Underflow?
: ( sum < bits )) { // Overflow?
return BOTTOM;
} else if ( sum == 0 ) {
return TypePtr::NULL_PTR;
} else {
return make( (address)sum );
}
}
default: ShouldNotReachHere();
}
return nullptr; // Lint noise
}
//------------------------------eq---------------------------------------------