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sav08:sign_analysis_of_expressions_and_programs [2008/05/07 00:17] vkuncak |
sav08:sign_analysis_of_expressions_and_programs [2008/05/07 01:08] vkuncak |
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| Abstract operations: $\oplus, \otimes : A^2 \to A$ defined by tables: | Abstract operations: $\oplus, \otimes : A^2 \to A$ defined by tables: | ||
| + | ===== Sign Analysis of Programs ===== | ||
| + | Prove that this program never reports error: | ||
| + | <code> | ||
| + | i = 20; | ||
| + | x = 2; | ||
| + | while (i > 0) { | ||
| + | x = x + 4; | ||
| + | i = i - 1; | ||
| + | } | ||
| + | if (x==0) { | ||
| + | error; | ||
| + | } else { | ||
| + | y = 1000/x; | ||
| + | } | ||
| + | </code> | ||
| + | |||
| + | Abstract state: map each variable to element of $A$. | ||
| + | |||
| + | * computation over control-flow graph | ||
| + | |||
| + | What does it mean for such computation to be correct? | ||