Assembler_x86.cpp char buffer deallocation

[Vladimir Kozlov]

The code is correct. The allocate is normal C++ allocate which use malloc so the 
buffer is in C heap.

Again, verify_oop() method is called during assembler code generation (for 
example, during JIT compiled code generation). Later when the compiled code is 
executed it references this message so it can print it when oop check in the 
stub fails.

Think about this as equivalent to C++ code: printf("Message"). "Message" string 
is kept in .data section whole time of program execution, it is not deallocated.

Vladimir

Vitaly Davidovich wrote:
> Hi Vladimir,
> 
> Right, so I did see that this buffer's address is taken and passed to 
> the stub generator that creates the verify_oop code.  What I couldn't 
> find was where this buffer was deallocated after the verify_oop 
> procedure was finished.  Since this is allocated via new(), how would 
> you deallocate it from generated code since presumably new() can be 
> using a custom allocator underneath? I realize this is debug code so 
> probably doesn't matter in practical terms.
> 
> I'm a bit unclear on whether you're saying this code is correct or not. :)
> 
> Thanks
> 
> Sent from my phone
> 
> On Oct 9, 2012 1:09 PM, "Vladimir Kozlov" <vladimir.kozlov at oracle.com 
> <mailto:vladimir.kozlov at oracle.com>> wrote:
> 
>     Vitaly,
> 
>     It is common mistake to mix code generation time and runtime
>     execution of the generated code. We need this buffer with a message
>     during runtime execution so we can deallocate it during code generation.
> 
>     Regards,
>     Vladimir
> 
>     Vitaly Davidovich wrote:
> 
>         Hi Volker,
> 
>         Yes sorry, I should've stated that I did see that it was guarded
>         by VerifyOops and I was just browsing the code - this is by no
>         means some production issue that I have.  Was just curious if I
>         missed something.
> 
>         Thanks
> 
>         Sent from my phone
> 
>         On Oct 9, 2012 9:47 AM, "Volker Simonis"
>         <volker.simonis at gmail.com <mailto:volker.simonis at gmail.com>
>         <mailto:volker.simonis at gmail.__com
>         <mailto:volker.simonis at gmail.com>>> wrote:
> 
>             Hi Vitaly,
> 
>             it looks not very professional indeed, however it is only in
>         debug
>             code or in code protected by development parameters
>         (-XX:+VerifyOops)
>             so it will not cause any trouble in the production VM.
>         Nevertheless it
>             should be cleaned up when somebody touches that file.
> 
>             Regards,
>             Volker
> 
>             On Tue, Oct 9, 2012 at 3:10 PM, Vitaly Davidovich
>         <vitalyd at gmail.com <mailto:vitalyd at gmail.com>
>             <mailto:vitalyd at gmail.com <mailto:vitalyd at gmail.com>>> wrote:
>              > Hi guys,
>              >
>              > I noticed that assembler_x86.cpp has a few places where a
>         char[]
>             is new()'d
>              > up to hold an error message when verifying an oop.  This
>         buffer
>             is passed to
>              > the stub routine, but I can't find where this buffer is then
>              > deleted/deallocated.  Am I missing something? Apologies
>         of this
>             is a silly
>              > question. :)
>              >
>              > Thanks
>              >
>              > Sent from my phone
>