Re: [boost] Review request: Boost.FSM
AMDG Andrey Semashev wrote:
Oh, you're right. But isn't it enough just to mark "m_fInitialized" as "volatile"? According to 1.9/7 it would enforce the compiler to initialize "m_StatesInfo" prior to setting "m_fInitialized".
No, m_StatesInfo has to be volatile too. In Christ, Steven Watanabe
Hello Steven, Monday, January 8, 2007, 11:26:29 PM, you wrote:
AMDG
Andrey Semashev wrote:
Oh, you're right. But isn't it enough just to mark "m_fInitialized" as "volatile"? According to 1.9/7 it would enforce the compiler to initialize "m_StatesInfo" prior to setting "m_fInitialized".
No, m_StatesInfo has to be volatile too.
Why? The Standard says all side effects prior to access to a volatile object will be completed at a sequence point (1.9/7, 1.9/11). There is a sequence point after returning from a function (1.9/17). At this sequence point all expressions of the function will be complete (IOW, m_StatesInfo will be initialized). So, in our case no matter what a compiler does, the call to "init_states_info" must be done before "m_fInitialized" assignment, shouldn't it? Actually, thinking of is some more I got some doubts about wether a compiler is allowed to shuffle expressions. The "init_states_info" function call and "m_fInitialized" assignment are both full-expressions and thus have sequence points at completion of each of them (1.9/16). So they should be executed in the the same order as they written in code. Sorry if I'm asking dumb questions, I'm just trying to get to the bottom of this. Am I wrong? -- Best regards, Andrey mailto:andysem@mail.ru
participants (2)
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Andrey Semashev -
Steven Watanabe