Introduce value-set supported simplifier for goto-symex #8642
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tautschnig
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qinheping,
feliperodri,
remi-delmas-3000,
kroening and
peterschrammel
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## develop #8642 +/- ##
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feliperodri
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Jun 18, 2025
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| // all pointed-to objects on the left-hand side are different from any of | ||
| // the pointed-to objects on the right-hand side | ||
| return expr.id() == ID_equal ? changed(static_cast<exprt>(false_exprt{})) | ||
| : changed(static_cast<exprt>(true_exprt{})); |
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If pointed-to objects are the same for LHS and RHS but for each object we have statically different symbolic offsets then we could conclude that the comparison is still always false ?
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I meant to say this still seems to rely only on object information, not really using offset info to the fullest ? but this might already be done somewhere else.
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Note this is simplify_inequality_pointer_object, which really is for POINTER_OBJECT(x) == POINTER_OBJECT(y) comparisons. There is try_evaluate_pointer_comparison where the above suggestions, however, might apply.
remi-delmas-3000
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Jun 18, 2025
peterschrammel
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Jun 19, 2025
Move `try_evaluate_pointer_comparison` to a simplifier that can eventually support more cases than just equalities in GOTO conditions. The initial change does not alter behaviour (except that previously `try_evaluate_pointer_comparison` was even used when simplification was disabled). A side-effect is that we can also clean up renamedt.
value-set based simplifications may be helpful well outside just GOTO conditions.
When all candidates in the value set have the same offset we can replace a pointer_offset expression by the offset value found in the value set.
The value set can help us infer that, e.g., a particular pointer cannot be among the ones assigned to __CPROVER_dead_object, whereby we can simplify R_OK/W_OK expressions.
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This release adds aarch64 va_list support (via diffblue#8572), which makes all tests pass on aarch64 Linux. We reworked expression simplification during symbolic execution (via diffblue#8642, diffblue#8647, diffblue#8627) to produce smaller and quicker-to-solve formulae for scenarios seen by our users.
tautschnig
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This release adds aarch64 va_list support (via diffblue#8572), which makes all tests pass on aarch64 Linux. We reworked expression simplification during symbolic execution (via diffblue#8642, diffblue#8647, diffblue#8627) to produce smaller and quicker-to-solve formulae for scenarios seen by our users.
tautschnig
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This release adds aarch64 va_list support (via diffblue#8572), which makes all tests pass on aarch64 Linux. We reworked expression simplification during symbolic execution (via diffblue#8642, diffblue#8647, diffblue#8627) to produce smaller and quicker-to-solve formulae for scenarios seen by our users.
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Move
try_evaluate_pointer_comparisonto a simplifier that can eventually support more cases than just equalities in GOTO conditions. The initial change does not alter behaviour (except that previouslytry_evaluate_pointer_comparisonwas even used when simplification was disabled).A side-effect is that we can also clean up renamedt.