On Thursday 07 April 2005 16:39, David Schwartz wrote: A bit off-topic, but...
> If you mean 'volatile', no, that doesn't do anything. Specifically, > 'volatile' has no special semantics for multi-processors. There may be > specific compilers where it has such semantics, but the standard doesn't > provide them. According to ISO 9899-1990, section 6.5.3: An object that has volatile-qualified type may be modified in ways unknown to the implementation or have other unknown side effects. Therefore any expression referring to such an object shall be evaluated strictly according to the rules of the abstract machine, as described in 5.1.2.3. Furthermore, at every sequence point the value last stored in the object shall agree with that prescribed by the abstract machine, EXCEPT AS MODIFIED BY THE UNKNOWN FACTORS MENTIONED PREVIOUSLY [emphasis added]. Translation: The compiler can't make assumptions about the state of a variable marked "volatile", and MUST generate code that writes every result stored there as well as code that reads the variable EVERY SINGLE TIME it appears in an expression. It has nothing to do with multi-processor coherency. Any compiler that generates code that deviates from this (even a little bit) isn't compliant with the standard. ______________________________________________________________________ OpenSSL Project http://www.openssl.org Development Mailing List openssl-dev@openssl.org Automated List Manager [EMAIL PROTECTED]
