RFR: 8266550: C2: mirror TypeOopPtr/TypeInstPtr/TypeAryPtr with TypeKlassPtr/TypeInstKlassPtr/TypeAryKlassPtr [v2]

[Vladimir Ivanov]

On Mon, 7 Jun 2021 12:38:28 GMT, Roland Westrelin <roland at openjdk.org> wrote:

>> This is some refactoring in another attempt to fix JDK-6312651
>> (Compiler should only use verified interface types for
>> optimization). Rather than propose the patch from:
>> 
>> https://mail.openjdk.java.net/pipermail/hotspot-compiler-dev/2019-May/033803.html
>> 
>> as a single big patch. I've been working on splitting it. The plan is
>> to have this and another refactoring patch that include no change to
>> the way interfaces are handled as preparation. Then only, in a third
>> patch, interface support along the lines of the patch I proposed 2
>> years ago would be introduces.
>> 
>> This patch changes the class hierarchy of types that C2 uses and
>> introduces TypeInstKlassPtr/TypeAryKlassPtr that mirror
>> TypeInstPtr/TypeAryPtr. The motivation for this is that a single:
>> 
>> ciKlass* _klass;
>> 
>> is no longer sufficient to describe a type (a set of interfaces must
>> also be carried around). That's not possible with TypeKlassPtr.
>> 
>> The meet methods for TypeInstPtr/TypeInstKlassPtr and
>> TypeAryPtr/TypeAryKlassPtr are largely similar. I moved the most
>> complicated logic in helper methods:
>> 
>> meet_instptr() and meet_aryptr()
>> 
>> (Thanks to Vladimir I for testing the refactoring patches)
>
> Roland Westrelin has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains one commit:
> 
>   instklassptr/aryklassptr

Another case is in `Compile::flatten_alias_type()`:

  // Flatten all to bottom for now
  switch( _AliasLevel ) {
  ...
  case 1:                       // Flatten to: oop, static, field or array
    switch (tj->base()) {
    case Type::RawPtr:   tj = TypeRawPtr::BOTTOM;   break;
    case Type::AryPtr:   // do not distinguish arrays at all
    case Type::InstPtr:  tj = TypeInstPtr::BOTTOM;  break;
    case Type::KlassPtr: tj = TypeInstKlassPtr::OBJECT; break;
    case Type::AnyPtr:   tj = TypePtr::BOTTOM;      break;  // caller checks it


`Type::KlassPtr` should be accompanied by `Type::InstKlassPtr` and `Type::AryKlassPtr` cases, shouldn't it?

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PR: https://git.openjdk.java.net/jdk/pull/3880