Re: [jira] Created: (HARMONY-5351) write barrier problem

[Xiao-Feng Li <xi...@gmail.com>]

On Dec 26, 2007 10:36 PM, YangBin (JIRA) <ji...@apache.org> wrote:
> write barrier problem
> ---------------------
>
>                  Key: HARMONY-5351
>                  URL: https://issues.apache.org/jira/browse/HARMONY-5351
>              Project: Harmony
>           Issue Type: Bug
>          Environment: Intel(R) Pentium(R) 4 CPU 3.00GHz
> Mem: 1GB
> DISK: 10GB
>             Reporter: YangBin
>
>
>    I am trying to implement a "root write barrier" that can dynamically trace root object in regs, stack.
>    The "gen_gc_mark_local" in cg.cpp may be generate the GC map, but when I add the root write barrier in there, the root value is zero.
>    I use gdb to trace jit, i find that "gen_write_barrier" is not compiled in the native code. When I omitted the following code in cg_instr.cpp:gen_write_barrier:
>     if (!doGenWB4J && !doGenWB4C) {
>         return;
>     }
>    the Harmony crash.
>
>   If I don't misunderstand,  write barrier in current Harmony  may be not right.
>
>    Would you like to give me some opinion about above problem?
>    I'm looking forwards to your letters.
>
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Bin, could you explain what you mean by "root write barrier"? Do you
mean to always record and update the rootset dynamically in jitted
code so that GC doesn't need to enumerate rootset for a collection? If
that's what you mean, the current write barrier is not designed for
that purpose. It's only for object field write barrier.

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