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sav08:semantics_of_field_reads_and_writes [2009/03/18 10:02] vkuncak |
sav08:semantics_of_field_reads_and_writes [2015/04/21 17:30] |
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| - | ====== Semantics of Field Reads and Writes ====== | ||
| - | How to model $x.f$ ? ++|term $f(x)$++ | ||
| - | |||
| - | How to model field assignment $x.f=y$ ? | ||
| - | ++++| | ||
| - | Use function update construct: | ||
| - | \[ | ||
| - | f = f(x:=y) | ||
| - | \] | ||
| - | State variable $f$, which denotes a function, is assigned an updated version of this function. | ||
| - | ++++ | ||
| - | |||
| - | What about null pointer checks? | ||
| - | |||
| - | Examples: | ||
| - | y = x.next.next | ||
| - | x.next.next.prev = y | ||
| - | (x = null | x.next == y) | ||
| - | |||
| - | Statement simplification. | ||
| - | |||
| - | Short-circuit evaluation. | ||
| - | |||
| - | Compiler intermediate representation is sometimes more convenient than source code | ||
| - | * or verification system can repeat the compilation process from source to relations (guarded commands) | ||
| - | * [[:compilation:top]] | ||