Re: Note on 109327

[Thien-Thi Nguyen <ttn@gnuvola.org>]

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() Dmitry Antipov <dmantipov@yandex.ru>
() Tue, 31 Jul 2012 17:50:43 +0400

   > I think to do this well you will need separate macros for getting
   > and setting.

   Sure, but it's almost impossible to do this at once.

Why?

   At the very beginning, it's possible to "overestimate" barrier
   assuming that each XVAR (obj, field) changes FIELD in OBJ; in the
   future, reads and writes may be separated, thus giving a precise
   write barrier.

I think you're saying that you prefer to do:

a1. substitute object access (whether LHS or RHS) w/ XVAR (obj, field)
a2. distinguish LHS (which could benefit from optimization) from RHS
a3. substitue LHS ‘XVAR (...) = value’ w/ SETVAR (obj, field, value)

instead of:

b1. distinguish LHS (which could benefit from optimization) from RHS
b2. substitute LHS object access w/ SETVAR (obj, field, value)
b3. substitute RHS object access w/ XVAR (obj, field)

Is my understanding correct?

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Thien-Thi Nguyen ..................................... GPG key: 4C807502
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