[jira] Resolved: (HARMONY-5016) [drlvm][jit][opt] code patching may corrupt calls to helpers on x86-64 in OPT mode

["Alexey Varlamov (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/HARMONY-5016?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Alexey Varlamov resolved HARMONY-5016.
--------------------------------------

    Resolution: Fixed

> [drlvm][jit][opt] code patching may corrupt calls to helpers on x86-64 in OPT mode
> ----------------------------------------------------------------------------------
>
>                 Key: HARMONY-5016
>                 URL: https://issues.apache.org/jira/browse/HARMONY-5016
>             Project: Harmony
>          Issue Type: Bug
>          Components: DRLVM
>         Environment: Linux x86-64
>            Reporter: Pavel Afremov
>            Assignee: Alexey Varlamov
>            Priority: Critical
>         Attachments: H5016.diff
>
>
> On Linux x86-64, DRL VM crashed by assert of null allocation handler (second parametr) in fast_gc_alloc.
> It called from JITed code 
> at org.apache.harmony.kernel.vm.VM.<clinit>
>  ...\drlvm\vm\vmcore\src\kernel_classes\javasrc\org\apache\harmony\kernel\vm\VM.java ln 120
> internedStrings = new InternMap(32768);
> The source of the bug is in folowing:
> 1.	If ofset between callee and caller fits in 32 bits signed value, OPT generates following code:
> 0x00002aab0b490000:     push   %rbx
> 0x00002aab0b490001:     mov    $0x90edf5,%rbx
> 0x00002aab0b49000b:     movb   $0x0,(%rbx)
> 0x00002aab0b49000e:     mov    $0x90edf4,%rbx
> 0x00002aab0b490018:     movb   $0x0,(%rbx)
> 0x00002aab0b49001b:     mov    $0x20,%edi
> 0x00002aab0b490020:     mov    $0x2c68,%rsi
> 0x00002aab0b49002a:     callq  0x2aaaac2bf950
> 2.	If offset more then 32 bits signed value OPT generates following code:
> 0x00002aab49c90000:     push   %rbx
> 0x00002aab49c90001:     mov    $0x9665e5,%rbx
> 0x00002aab49c9000b:     movb   $0x0,(%rbx)
> 0x00002aab49c9000e:     mov    $0x9665e4,%rbx
> 0x00002aab49c90018:     movb   $0x0,(%rbx)
> 0x00002aab49c9001b:     mov    $0x20,%edi
> 0x00002aab49c90020:     mov    $0x2aaaac2bf950,%r11
> 0x00002aab49c9002a:     data16
> 0x00002aab49c9002b:     nop
> 0x00002aab49c9002c:     rex64Z callq  *%r11
> In this code second parameter is missed, rsi is not initialized, and fast_gc_alloc  asserts by this reason.
> I think that this bug can be reproduced on any x86-64 platform, both Linux and Windows.
> But I can reproduce it on Linux x86-64 machine only.
> To reproduce the bug, run any class or test in OPT mode with large heap on Linux x86-64 debug build, like in following command:
> .../jdk/jre/bin/java -Xem:opt -Xmx3500m Hi
> DRLVM in JET mode works OK.

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