[10] RFR(S): 8188785: CCP sets invalid type for java mirror load

[Tobias Hartmann]

Hi Vladimir,

On 23.10.2017 18:19, Vladimir Kozlov wrote:
> I think we need to file a bug or rfe to fix other cases too.

Okay, it's difficult to file a bug for a not yet known issue so I've filed an RFE to look into this:
https://bugs.openjdk.java.net/browse/JDK-8189856

> In add_users_to_worklist() you don't need to check type ut !=
>  > type(u) - just push node on worklist.

Right, fixed:
http://cr.openjdk.java.net/~thartmann/8188785/webrev.02/

> Also can you remove ut->isa_instptr() check in *both* cases. And use u->is_Mem() instead of u->Opcode() == Op_LoadP to 
> cover stores too.
> The motivation is that original LoadP is raw as result memory operations which use it may look for more precise type of 
> the field somewhere so they should be on worklist.

Why is that necessary? If the raw LoadP changes its type, all direct users will be added to the worklist anyway.

The problem in the failing case is that the type of the AddP changed but the type of the raw LoadP didn't (it stays 
raw). However, the InstPtr load depends on the type of the AddP:

   InstPtrLoadP(RawLoadP(AddP(..)))

Do you expect other memory users of the raw LoadP to depend on the type of the AddP? I think we should only add handling 
for known special cases but here's the corresponding webrev:
http://cr.openjdk.java.net/~thartmann/8188785/webrev.03/

Thanks,
Tobias