Request for reviews (S): 6820514: meet not symmetric failure in ctw

[Vladimir Kozlov]

No, it is not true. The original comment's line is still true

 >       //  AnyNull |  U-AN    |................Unloaded......................|

meet_ptr() maps almost everything to the original PRT:

 >   //              TopPTR,    AnyNull,   Constant, Null,   NotNull, BotPTR,
 >   { /* AnyNull */ AnyNull,   AnyNull,   Constant, BotPTR, NotNull, BotPTR,},

except TOP which corresponds to the special case in the code table and NULL which
is not in the table.

Vladimir

Tom Rodriguez wrote:
> There's a nice comment above this code and it would be nice if the table and code agreed in both order and results.
> 
>       // Meet unloaded class with java/lang/Object
>       //
>       // Meet
>       //          |                     Unloaded Class
>       //  Object  |   TOP    |   AnyNull | Constant |   NotNull |  BOTTOM   |
>       //  ===================================================================
>       //   TOP    | ..........................Unloaded......................|
>       //  AnyNull |  U-AN    |................Unloaded......................|
>       // Constant | ... O-NN .................................. |   O-BOT   |
>       //  NotNull | ... O-NN .................................. |   O-BOT   |
>       //  BOTTOM  | ........................Object-BOTTOM ..................|
> 
> Your changes appear to make this line:
> 
>       //  AnyNull |  U-AN    |................Unloaded......................|
> 
> become
> 
>       //  AnyNull |...........................  U-AN  ......................|
> 
> The -AN part isn't quite true since we're returning the results of meet_ptr which uses the table below.  AnyNull meeting NotNull returns NotNull.  The Constant line in the comments seems to be wrong too.
> 
> const TypePtr::PTR TypePtr::ptr_meet[TypePtr::lastPTR][TypePtr::lastPTR] = {
>   //              TopPTR,    AnyNull,   Constant, Null,   NotNull, BotPTR,
>   { /* Top     */ TopPTR,    AnyNull,   Constant, Null,   NotNull, BotPTR,},
>   { /* AnyNull */ AnyNull,   AnyNull,   Constant, BotPTR, NotNull, BotPTR,},
>   { /* Constant*/ Constant,  Constant,  Constant, BotPTR, NotNull, BotPTR,},
>   { /* Null    */ Null,      BotPTR,    BotPTR,   Null,   BotPTR,  BotPTR,},
>   { /* NotNull */ NotNull,   NotNull,   NotNull,  BotPTR, NotNull, BotPTR,},
>   { /* BotPTR  */ BotPTR,    BotPTR,    BotPTR,   BotPTR, BotPTR,  BotPTR,}
> };
> 
> The code itself looks right to me after much rereading of the meet logic.
> 
> tom
> 
> 
> On Mar 20, 2009, at 11:31 PM, Vladimir Kozlov wrote:
> 
>>
>> http://cr.openjdk.java.net/~kvn/6820514/webrev.00
>>
>> Fixed 6820514: meet not symmetric failure in ctw
>>
>> Problem:
>> Missing instance_id meet for the case j.l.Object:NotNull meets
>> unloaded instance klass.
>>
>> Solution:
>> Add missing code.
>>
>> Reviewed by:
>>
>> Fix verified (y/n): y, ctw test from bug
>>
>> Other testing:
>> JPRT
>>