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DCA: measure implicit Python call exception edges #159

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DCA: measure implicit Python call exception edges #159

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16 changes: 8 additions & 8 deletions python/ql/lib/semmle/python/controlflow/internal/AstNodeImpl.qll
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Original file line number Diff line number Diff line change
Expand Up @@ -1633,21 +1633,21 @@ private module Input implements InputSig1, InputSig2 {
* its normal evaluation (not via an explicit `raise`/`assert`, which are
* modeled separately).
*
* The set mirrors what the legacy CFG used to flag implicitly: function
* calls (anything can raise), attribute access (`AttributeError`),
* subscript access (`IndexError`/`KeyError`/`TypeError`), arithmetic and
* comparison operators (`TypeError`/`ZeroDivisionError`), imports
* (`ImportError`/`ModuleNotFoundError`), and generator/coroutine
* suspension points (`await`/`yield`/`yield from`).
* This experimental DCA variant excludes ordinary function calls to measure
* the performance and precision cost of conservatively treating every call
* as potentially throwing. Other implicit exception sources remain modeled:
* attribute access (`AttributeError`), subscript access
* (`IndexError`/`KeyError`/`TypeError`), arithmetic and comparison operators
* (`TypeError`/`ZeroDivisionError`), imports
* (`ImportError`/`ModuleNotFoundError`), and generator/coroutine suspension
* points (`await`/`yield`/`yield from`).
*
* Bare `Name` reads are intentionally excluded — modeling every name
* read as `mayThrow` would explode CFG edge count for negligible
* analysis value. `BoolExpr`/`IfExp` containers are also excluded; the
* operands they evaluate contribute their own exception edges.
*/
private predicate exprMayThrow(Py::Expr e) {
e instanceof Py::Call
or
e instanceof Py::Attribute
or
e instanceof Py::Subscript
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