Please review fix for 7120481 storeStore barrier in constructor with final field

[Vitaly Davidovich]

Hi Jiangli,

Isn't the "sy" option a full membar? I think the "st" option is equivalent
to StoreStore.

Vitaly

Sent from my phone
On Feb 8, 2012 6:37 PM, "Jiangli Zhou" <jiangli.zhou at oracle.com> wrote:

> **
> Hi,
>
> Please review the following webrevs for 7120481 storeStore barrier in
> constructor with final field:
>
> http://javaweb.sfbay.sun.com/~jianzhou/webrev.storestore/
> http://javaweb.sfbay.sun.com/~jianzhou/webrev.storestore.closed/
>
> Both c1 and the template interpreter are fixed to add the needed memory
> barrier. For a constructor that writes final field, a release barrier is
> added in the compiled method before the constructor returns if the
> constructor is not inlined. When the constructor is inlined, a release
> barrier is added at the end of the inlined constructor. The changes are
> done in the shared c1 code only, the platform specific code already knows
> whether memory barrier instructions should be generated for the platform.
> Following are ARM examples of a compiled constructor that writes final
> field after the fix. For the template interpreter, a new opcode
> '_return_with_membar' is added. During method rewriting, the VM detects if
> a constructor writes final. If so, the _return opcode is changed into
> _return_with_membar for the constructor. The ARM and PPC template
> interpreter code are changed to issue a storesotre barrier for the new
> opcode.
>
> Not inlined:
>
>   0x41386450: mov    r1, r0
>   0x41386454: mov    r0, r1          ;*invokespecial <init>
>                                         ; - HasFinal::<init>@1 (line 19)
>   0x41386458: str    r1, [sp, #16]
>   0x4138645c: bl    0x41325d00      ; OopMap{[16]=Oop off=48}
>                                         ;*invokespecial <init>
>                                         ; - HasFinal::<init>@1 (line 19)
>                                         ;   {optimized virtual_call}
>   0x41386460: mov    r0, #100    ; 0x64
>   0x41386464: ldr    r1, [sp, #16]
>   0x41386468: str    r0, [r1, #8]    ;*putfield x
>                                         ; - HasFinal::<init>@7 (line 20)
>   0x4138646c: dmb    sy
>   0x41386470: add    sp, sp, #24
>   0x41386474: pop    {fp, lr}
>   0x41386478: movw    ip, #53248    ; 0xd000
>   0x4138647c: movt    ip, #16397    ; 0x400d
>   0x41386480: ldr    ip, [ip]        ;   {poll_return}
>   0x41386484: bx    lr
>   0x41386488: nop            ; (mov r0, r0)
>
>
> Inlined:
>
>   0x413797e0: mov    r1, r0
>   0x413797e4: mov    r0, r1          ;*invokespecial <init>
>                                         ; - HasFinal::<init>@1 (line 19)
>                                         ; - FinalTest::main at 25 (line 11)
>   0x413797e8: str    r1, [sp, #32]
>   0x413797ec: bl    0x41318d00      ; OopMap{[32]=Oop off=272}
>                                         ;*invokespecial <init>
>                                         ; - HasFinal::<init>@1 (line 19)
>                                         ; - FinalTest::main at 25 (line 11)
>                                         ;   {optimized virtual_call}
>   0x413797f0: mov    r0, #100    ; 0x64
>   0x413797f4: ldr    r1, [sp, #32]
>   0x413797f8: str    r0, [r1, #8]    ;*putfield x
>                                         ; - HasFinal::<init>@7 (line 20)
>                                         ; - FinalTest::main at 25 (line 11)
>   0x413797fc: dmb    sy
>   0x41379800: movw    r0, #23416    ; 0x5b78
>                                         ;   {oop(a 'java/lang/Class' =
> 'FinalTest')}
>   0x41379804: movt    r0, #17206    ; 0x4336
>   0x41379808: str    r1, [r0, #104]    ; 0x68
>
> Thanks,
>
> Jiangli
>
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