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From "Xiaoming Gu (JIRA)" <j...@apache.org>
Subject [jira] Commented: (HARMONY-6027) [drlvm][jit] An incorrect register assignment in graph coloring register allocation
Date Thu, 27 Nov 2008 07:45:44 GMT

    [ https://issues.apache.org/jira/browse/HARMONY-6027?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12651276#action_12651276
] 

Xiaoming Gu commented on HARMONY-6027:
--------------------------------------

With some debugging on graph-coloring RA, I find the bug from register assignment. Following
are the details:

Opnd#165 interferes with Opnd#20 which uses EDX. When assigning register to Opnd#165, it doesn't
think DH is not available because it forgets to check the size of operands (Opnd#165 is 8-bit
and Opnd#20 is 32-bit). Then DH is assigned to Opnd#165 incorrectly.

Maybe the same problem exists in other RA.

> [drlvm][jit] An incorrect register assignment in graph coloring register allocation
> -----------------------------------------------------------------------------------
>
>                 Key: HARMONY-6027
>                 URL: https://issues.apache.org/jira/browse/HARMONY-6027
>             Project: Harmony
>          Issue Type: Bug
>          Components: DRLVM
>         Environment: IA32 Windows
>            Reporter: Xiaoming Gu
>
> When running crypto.rsa with early_prop bypassed, a run-time bug happens because of the
following code for spec/benchmarks/crypto/rsa/Main.runMultiEncryptDecrypt().
>     with early_prop
> 	0230D094 I140: MOVSX t166(ESI):I_32,s164(EBX):I_32 
>     without early_prop
> 	0230D0B4 I663: MOV t165(DH):I_8,s164(EBX):I_32 
> 	0230D0B6 I140: MOVSX t166(ESI):I_32,t165(DH):I_8 
> After checking all the code in runMultiEncryptDecrypt(), I find EDX is defined and used
several time in this method. With the control flow graph, I think the bug comes from that
EDX is changed uncarefully for the above modification on DH.
> This bug is similar to H6016 from the view of early_prop. (https://issues.apache.org/jira/browse/HARMONY-6016)
But they trig different bugs.

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