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sav07_lecture_20 [2007/06/05 19:06] kremena.diatchka old revision restored |
sav07_lecture_20 [2008/05/22 13:45] vkuncak |
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| - must follow protocol: (open (read+write)* close)* | - must follow protocol: (open (read+write)* close)* | ||
| - must follow protocol: (startLog stopLog)* | - must follow protocol: (startLog stopLog)* | ||
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| ==== Semantics for language with procedure calls ==== | ==== Semantics for language with procedure calls ==== | ||
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| $(s, l, c, t)$ | $(s, l, c, t)$ | ||
| - | Here $l \in L$, where $L$ is the set of local variables of a procedure. Everything would be popped off from $l$ when the procedure returns control to the callee. | + | Here $l \in L$, where $L$ is the set of mappings of local variables of a procedure to their values. Furthermore, on each procedure call, the program pushes $l$ on the stack along with the program point. Everything would be popped off from $l$ when the procedure returns control to the callee. |
| One instance where small step semantics would be necessary is in concurrency, so that we can take into account interleaving. | One instance where small step semantics would be necessary is in concurrency, so that we can take into account interleaving. | ||
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| When a procedure call is encountered, it is replaced by the statements of the procedure (so the procedure code is inlined with the code of the callee). A problem arises when the procedure being inlined is recursive. One approach to dealing with this situation is to inline the recursive procedure a few times, and then treat the recursive call as a havoc statement (as described above). However, even if this is done, inlining increases the size of the code exponentially. | When a procedure call is encountered, it is replaced by the statements of the procedure (so the procedure code is inlined with the code of the callee). A problem arises when the procedure being inlined is recursive. One approach to dealing with this situation is to inline the recursive procedure a few times, and then treat the recursive call as a havoc statement (as described above). However, even if this is done, inlining increases the size of the code exponentially. | ||
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| === Treat procedure calls as goto statements === | === Treat procedure calls as goto statements === | ||