RFR: 8311583: tableswitch broken by JDK-8310577 [v2]

[Coleen Phillimore]

On Fri, 7 Jul 2023 04:11:30 GMT, David Holmes <dholmes at openjdk.org> wrote:

>> Coleen Phillimore has updated the pull request incrementally with one additional commit since the last revision:
>> 
>>   David's feedback.
>
> src/hotspot/share/interpreter/bytecodes.cpp line 390:
> 
>> 388:       // Promote calculation to 64 bits to do range checks, used by the verifier.
>> 389:       int64_t lo = (int)Bytes::get_Java_u4(aligned_bcp + 1*jintSize);
>> 390:       int64_t hi = (int)Bytes::get_Java_u4(aligned_bcp + 2*jintSize);
> 
> Are the int casts needed?

Yes they are.    get_Java_u4 returns u4 (unsigned) and the 'int' cast sign extends it to int, then further sign extended to int64_t for the length calculation.  The tableswitch bytecode operands are signed int.


static inline u4   get_Java_u4(address p)           { return get_Java<u4>(p); }

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PR Review Comment: https://git.openjdk.org/jdk/pull/14788#discussion_r1256138404