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Python: introduce new-CFG facade
Adds 'Cfg.qll' alongside 'AstNodeImpl.qll' in the controlflow internal
package. The facade re-exposes the same API surface as the legacy
'semmle/python/Flow.qll' (ControlFlowNode, BasicBlock, NameNode, CallNode,
AttrNode, ImportExprNode, ImportMemberNode, ImportStarNode, SubscriptNode,
CompareNode, IfExprNode, AssignmentExprNode, BinaryExprNode, BoolExprNode,
UnaryExprNode, DefinitionNode, DeletionNode, ForNode, RaiseStmtNode,
StarredNode, ExceptFlowNode, ExceptGroupFlowNode, TupleNode, ListNode,
SetNode, DictNode, IterableNode, NameConstantNode), but is implemented
on top of the new shared CFG via 'AstNodeImpl.qll'.
The variable-identity predicates ('NameNode.defines', '.uses',
'.deletes', '.isLocal', '.isNonLocal', ...) are one-line bridges to the
underlying AST predicates ('Name.defines', '.uses', '.deletes'),
mirroring the Java pattern.
Re-exports 'EntryBasicBlock' and 'dominatingEdge/2' from the shared
'BB::CfgSig' produced by 'AstNodeImpl.qll', so downstream consumers
(e.g. the SSA adapter) can wire the new CFG into other shared modules
that expect a 'CfgSig' implementation.
This facade is not yet consumed by the dataflow library — that is the
next phase.
Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
This commit is contained in:
yoff
836
python/ql/lib/semmle/python/controlflow/internal/Cfg.qll
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836
python/ql/lib/semmle/python/controlflow/internal/Cfg.qll
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@@ -0,0 +1,836 @@
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/**
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* Provides a Python control flow graph facade backed by the shared
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* `codeql.controlflow.ControlFlowGraph` library (via `AstNodeImpl.qll`).
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*
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* This module re-exposes the same API surface as `semmle/python/Flow.qll`
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* (the legacy CFG), but is implemented on the new shared CFG. It is
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* intended as a drop-in replacement for use by the Python dataflow library
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* and other downstream code.
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*
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* Layering follows the Java pattern (`java/ql/lib/semmle/code/java/Expr.qll`
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* and `SsaImpl.qll`): variable identity and similar AST-level semantics
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* live on the Python AST classes (`Name.defines(v)`, `Name.uses(v)`, ...);
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* the CFG layer is purely positional, with `toAst` / `getNode` bridging
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* back to the AST. The shared SSA library can then be parameterized on
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* (`BasicBlock`, `int`) directly, with no CFG-level variable predicates.
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*/
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overlay[local?]
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module;
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private import python as Py
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private import semmle.python.controlflow.internal.AstNodeImpl as CfgImpl
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private import codeql.controlflow.SuccessorType
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/**
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* Gets the Python AST node corresponding to CFG node `n`, if any.
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*
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* Entry/exit/synthetic CFG nodes have no Python AST node, so this is
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* partial.
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*/
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private Py::AstNode toAst(CfgImpl::ControlFlowNode n) {
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result = CfgImpl::astNodeToPyNode(n.getAstNode())
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}
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/**
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* Holds if `n` is a CFG node representing the canonical position for an
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* AST node from the dataflow library's perspective.
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*
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* For most expressions this is the "after"-evaluation point (post-order
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* representative). For statements it is the post-order node when one
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* exists. We additionally include the synthetic entry/exit nodes for the
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* benefit of API consumers that ask "is this the entry node of a scope?".
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*
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* In conditional contexts the after-position of a boolean expression
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* splits into separate `isAfterTrue` and `isAfterFalse` nodes; both are
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* canonical, so a single AST expression may correspond to more than one
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* `ControlFlowNode`.
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*/
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private predicate isCanonical(CfgImpl::ControlFlowNode n) {
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n.isAfter(_)
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or
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n instanceof CfgImpl::ControlFlow::EntryNode
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or
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n instanceof CfgImpl::ControlFlow::ExitNode
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}
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/**
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* A control flow node. Control flow nodes have a many-to-one relation
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* with syntactic nodes, although most syntactic nodes have only one
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* corresponding control flow node.
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*
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* Edges between control flow nodes include exceptional as well as normal
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* control flow.
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*/
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class ControlFlowNode extends CfgImpl::ControlFlowNode {
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ControlFlowNode() { isCanonical(this) }
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/** Gets the syntactic element corresponding to this flow node, if any. */
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Py::AstNode getNode() { result = toAst(this) }
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/** Gets a predecessor of this flow node. */
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ControlFlowNode getAPredecessor() { this = result.getASuccessor() }
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/** Gets a successor of this flow node. */
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pragma[inline]
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ControlFlowNode getASuccessor() { result = nextCanonical(this) }
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/** Gets a successor for this node if the relevant condition is True. */
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ControlFlowNode getATrueSuccessor() {
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super.isAfterTrue(_) and
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exists(CfgImpl::ControlFlowNode other | other.isAfterFalse(super.getAstNode())) and
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result = nextCanonical(this)
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}
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/** Gets a successor for this node if the relevant condition is False. */
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ControlFlowNode getAFalseSuccessor() {
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super.isAfterFalse(_) and
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exists(CfgImpl::ControlFlowNode other | other.isAfterTrue(super.getAstNode())) and
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result = nextCanonical(this)
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}
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/** Gets a successor for this node if an exception is raised. */
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ControlFlowNode getAnExceptionalSuccessor() {
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exists(CfgImpl::ControlFlowNode mid |
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mid = super.getAnExceptionSuccessor() and
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result = nextCanonicalFrom(mid)
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)
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}
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/** Gets a successor for this node if no exception is raised. */
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ControlFlowNode getANormalSuccessor() {
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result = this.getASuccessor() and
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not result = this.getAnExceptionalSuccessor()
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}
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/** Gets the basic block containing this flow node. */
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BasicBlock getBasicBlock() { result = super.getBasicBlock() }
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/** Gets the scope containing this flow node. */
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Py::Scope getScope() { result = super.getEnclosingCallable().asScope() }
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/** Gets the enclosing module. */
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Py::Module getEnclosingModule() { result = this.getScope().getEnclosingModule() }
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/** Gets the immediate dominator of this flow node. */
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ControlFlowNode getImmediateDominator() {
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// Defined positionally via the basic-block dominance tree.
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exists(BasicBlock bb, int i | bb.getNode(i) = this |
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// Predecessor within the same basic block.
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i > 0 and result = bb.getNode(i - 1)
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or
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// First node of `bb`: dominator is the last node of the immediate dominator block.
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i = 0 and result = bb.getImmediateDominator().getLastNode()
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)
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}
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/** Holds if this strictly dominates `other`. */
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pragma[inline]
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predicate strictlyDominates(ControlFlowNode other) { super.strictlyDominates(other) }
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/** Holds if this dominates `other` (reflexively). */
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pragma[inline]
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predicate dominates(ControlFlowNode other) { super.dominates(other) }
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/** Holds if this is the first node in its enclosing scope. */
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predicate isEntryNode() { this instanceof CfgImpl::ControlFlow::EntryNode }
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/** Holds if this is the first node of a module. */
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predicate isModuleEntry() {
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this.isEntryNode() and super.getAstNode().asScope() instanceof Py::Module
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}
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/** Holds if this node may exit its scope by raising an exception. */
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predicate isExceptionalExit(Py::Scope s) {
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this instanceof CfgImpl::ControlFlow::ExceptionalExitNode and
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super.getEnclosingCallable().asScope() = s
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}
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/** Holds if this node is a normal (non-exceptional) exit. */
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predicate isNormalExit() { this instanceof CfgImpl::ControlFlow::NormalExitNode }
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// ===== AST-shape predicates (bridges to the wrapped Python AST) =====
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/** Holds if this flow node is a load (including those in augmented assignments). */
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predicate isLoad() {
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exists(Py::Expr e | e = toAst(this) | py_expr_contexts(_, 3, e) and not augstore(_, this))
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}
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/** Holds if this flow node is a store (including those in augmented assignments). */
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predicate isStore() {
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exists(Py::Expr e | e = toAst(this) | py_expr_contexts(_, 5, e) or augstore(_, this))
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}
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/** Holds if this flow node is a delete. */
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predicate isDelete() { exists(Py::Expr e | e = toAst(this) | py_expr_contexts(_, 2, e)) }
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/** Holds if this flow node is a parameter. */
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predicate isParameter() { exists(Py::Expr e | e = toAst(this) | py_expr_contexts(_, 4, e)) }
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/** Holds if this flow node is a store in an augmented assignment. */
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predicate isAugStore() { augstore(_, this) }
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/** Holds if this flow node is a load in an augmented assignment. */
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predicate isAugLoad() { augstore(this, _) }
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/** Holds if this flow node corresponds to a literal. */
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predicate isLiteral() {
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toAst(this) instanceof Py::Bytes or
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toAst(this) instanceof Py::Dict or
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toAst(this) instanceof Py::DictComp or
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toAst(this) instanceof Py::Set or
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toAst(this) instanceof Py::SetComp or
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toAst(this) instanceof Py::Ellipsis or
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toAst(this) instanceof Py::GeneratorExp or
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toAst(this) instanceof Py::Lambda or
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toAst(this) instanceof Py::ListComp or
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toAst(this) instanceof Py::List or
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toAst(this) instanceof Py::Num or
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toAst(this) instanceof Py::Tuple or
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toAst(this) instanceof Py::Unicode or
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toAst(this) instanceof Py::NameConstant
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}
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/** Holds if this flow node corresponds to an attribute expression. */
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predicate isAttribute() { toAst(this) instanceof Py::Attribute }
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/** Holds if this flow node corresponds to a subscript expression. */
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predicate isSubscript() { toAst(this) instanceof Py::Subscript }
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/** Holds if this flow node corresponds to an import member. */
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predicate isImportMember() { toAst(this) instanceof Py::ImportMember }
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/** Holds if this flow node corresponds to a call. */
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predicate isCall() { toAst(this) instanceof Py::Call }
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/** Holds if this flow node corresponds to an import. */
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predicate isImport() { toAst(this) instanceof Py::ImportExpr }
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/** Holds if this flow node corresponds to a conditional expression. */
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predicate isIfExp() { toAst(this) instanceof Py::IfExp }
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/** Holds if this flow node corresponds to a function definition expression. */
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predicate isFunction() { toAst(this) instanceof Py::FunctionExpr }
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/** Holds if this flow node corresponds to a class definition expression. */
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predicate isClass() { toAst(this) instanceof Py::ClassExpr }
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/** Internal: raw successor predicate that does NOT skip non-canonical nodes. */
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CfgImpl::ControlFlowNode getASuccessorRaw() { result = super.getASuccessor() }
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}
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/**
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* Holds if `n` is an augmented assignment load and `store` is the
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* corresponding store node.
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*/
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private predicate augstore(ControlFlowNode load, ControlFlowNode store) {
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exists(Py::Expr load_store | exists(Py::AugAssign aa | aa.getTarget() = load_store) |
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toAst(load) = load_store and
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toAst(store) = load_store and
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load.strictlyDominates(store)
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)
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}
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/**
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* Gets the nearest canonical CFG node reachable from `n` via one or more
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* raw CFG edges (skipping non-canonical intermediaries).
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*/
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private CfgImpl::ControlFlowNode nextCanonicalFrom(CfgImpl::ControlFlowNode n) {
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result = n.getASuccessor() and isCanonical(result)
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or
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exists(CfgImpl::ControlFlowNode mid |
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mid = n.getASuccessor() and
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not isCanonical(mid) and
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result = nextCanonicalFrom(mid)
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)
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}
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/** Gets the nearest canonical CFG successor of canonical node `n`. */
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private ControlFlowNode nextCanonical(ControlFlowNode n) { result = nextCanonicalFrom(n) }
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/**
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* A basic block — a maximal-length sequence of control flow nodes such
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* that no node except the first has a predecessor outside the sequence,
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* and no node except the last has a successor outside the sequence.
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*/
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class BasicBlock extends CfgImpl::BasicBlock {
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/** Gets the `n`th node in this basic block, restricted to canonical nodes. */
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ControlFlowNode getNode(int n) {
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result = rank[n + 1](ControlFlowNode node, int i | super.getNode(i) = node | node order by i)
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}
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/** Gets a node in this basic block. */
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ControlFlowNode getANode() { result = this.getNode(_) }
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/** Gets the first canonical node in this basic block. */
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ControlFlowNode firstNode() { result = this.getNode(0) }
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/** Gets the last canonical node in this basic block. */
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ControlFlowNode getLastNode() { result = this.getNode(max(int n | exists(this.getNode(n)))) }
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/** Holds if this basic block contains `node`. */
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predicate contains(ControlFlowNode node) { node = this.getANode() }
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// Inherited from the shared library's `BasicBlock`:
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// getASuccessor(), getASuccessor(SuccessorType), getAPredecessor(),
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// getNode(int) (raw, includes non-canonical), getANode() (raw),
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// strictlyDominates(), dominates(), getImmediateDominator(),
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// length(), inLoop().
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// We expose canonical-only positional access via `getNode(int)` below
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// (shadows the shared-lib version) and additional Python-style helpers.
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/** Gets a true successor to this basic block. */
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BasicBlock getATrueSuccessor() {
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result = super.getASuccessor(any(BooleanSuccessor t | t.getValue() = true))
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}
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/** Gets a false successor to this basic block. */
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BasicBlock getAFalseSuccessor() {
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result = super.getASuccessor(any(BooleanSuccessor t | t.getValue() = false))
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}
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/** Gets an unconditional successor to this basic block. */
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BasicBlock getAnUnconditionalSuccessor() {
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result = super.getASuccessor() and
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not result = this.getATrueSuccessor() and
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not result = this.getAFalseSuccessor()
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}
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/** Gets an exceptional successor to this basic block. */
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BasicBlock getAnExceptionalSuccessor() { result = super.getASuccessor(any(ExceptionSuccessor t)) }
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/**
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* Holds if this basic block is in the dominance frontier of `df`.
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*
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* Note: implemented locally rather than via the shared lib, which
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* doesn't currently expose a `dominanceFrontier` predicate at this
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* level.
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*/
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predicate inDominanceFrontier(BasicBlock df) {
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this = df.getAPredecessor() and not this = df.getImmediateDominator()
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or
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exists(BasicBlock prev | prev.inDominanceFrontier(df) |
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this = prev.getImmediateDominator() and
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not this = df.getImmediateDominator()
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)
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}
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/** Holds if this basic block strictly reaches `other`. */
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predicate strictlyReaches(BasicBlock other) { super.getASuccessor+() = other }
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/** Holds if this basic block reaches `other` (reflexively). */
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predicate reaches(BasicBlock other) { this = other or this.strictlyReaches(other) }
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/** Holds if flow from this basic block reaches a normal exit from its scope. */
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predicate reachesExit() {
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this.getANode() instanceof CfgImpl::ControlFlow::NormalExitNode
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or
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exists(BasicBlock succ | succ = super.getASuccessor() and succ.reachesExit())
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}
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/** Gets the scope of this basic block. */
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Py::Scope getScope() { exists(ControlFlowNode n | n = this.getANode() | result = n.getScope()) }
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/** Holds if flow from this BasicBlock always reaches `succ`. */
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predicate alwaysReaches(BasicBlock succ) {
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succ = this
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or
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strictcount(BasicBlock s | s = super.getASuccessor()) = 1 and
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succ = super.getASuccessor()
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or
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forex(BasicBlock immsucc | immsucc = super.getASuccessor() | immsucc.alwaysReaches(succ))
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}
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}
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// ===========================================================================
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// Re-exports for SSA / dominance consumers
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//
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// The shared `BB::CfgSig` requires `EntryBasicBlock` and `dominatingEdge` in
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// addition to the BasicBlock class we already expose. They are provided by
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// the shared CFG library on the `BB::Make` instantiation produced by
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// `AstNodeImpl.qll`.
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// ===========================================================================
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/** An entry basic block, that is, a basic block whose first node is an entry node. */
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class EntryBasicBlock = CfgImpl::Cfg::EntryBasicBlock;
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/**
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* Holds if `bb1` has `bb2` as a direct successor and the edge between `bb1`
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* and `bb2` is a dominating edge.
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*/
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predicate dominatingEdge = CfgImpl::Cfg::dominatingEdge/2;
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// ===========================================================================
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// AST-shape subclasses of ControlFlowNode
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//
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// Each class is a thin wrapper around the canonical CFG node for a given
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// kind of Python AST node. Methods that take/return CFG nodes delegate to
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// the AST and re-resolve back via `Expr.getAFlowNode()` from `Flow.qll`
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// while we are in the migration period; once that is gone we will use a
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// new-CFG-local resolution. For now, expressions navigated through these
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// subclasses are looked up by AST identity, and the dominance constraint
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// from the old CFG (`result.getBasicBlock().dominates(this.getBasicBlock())`)
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// is preserved.
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// ===========================================================================
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/** Gets the canonical `ControlFlowNode` for AST expression `e`. */
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ControlFlowNode astExprToCfg(Py::Expr e) { result.getNode() = e }
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/** A control flow node corresponding to a `Name` or `PlaceHolder` expression. */
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class NameNode extends ControlFlowNode {
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NameNode() {
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toAst(this) instanceof Py::Name
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or
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toAst(this) instanceof Py::PlaceHolder
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}
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/** Holds if this flow node defines the variable `v`. */
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predicate defines(Py::Variable v) {
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exists(Py::Name n | n = toAst(this) and n.defines(v)) and
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not this.isLoad()
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}
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/** Holds if this flow node deletes the variable `v`. */
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predicate deletes(Py::Variable v) { exists(Py::Name n | n = toAst(this) and n.deletes(v)) }
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/** Holds if this flow node uses the variable `v`. */
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predicate uses(Py::Variable v) {
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this.isLoad() and
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exists(Py::Name u | u = toAst(this) and u.uses(v))
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or
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exists(Py::PlaceHolder u |
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u = toAst(this) and u.getVariable() = v and u.getCtx() instanceof Py::Load
|
||||
)
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}
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/** Gets the identifier of this name node. */
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string getId() {
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result = toAst(this).(Py::Name).getId()
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or
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result = toAst(this).(Py::PlaceHolder).getId()
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||||
}
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/** Holds if this is a use of a local variable. */
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predicate isLocal() { exists(Py::Variable v | this.uses(v) and v instanceof Py::LocalVariable) }
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/** Holds if this is a use of a non-local variable. */
|
||||
predicate isNonLocal() {
|
||||
exists(Py::Variable v | this.uses(v) and v.getScope() != this.getScope())
|
||||
}
|
||||
|
||||
/** Holds if this is a use of a global (including builtin) variable. */
|
||||
predicate isGlobal() { exists(Py::Variable v | this.uses(v) and v instanceof Py::GlobalVariable) }
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a named constant (`None`, `True`, `False`). */
|
||||
class NameConstantNode extends NameNode {
|
||||
NameConstantNode() { toAst(this) instanceof Py::NameConstant }
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a call. */
|
||||
class CallNode extends ControlFlowNode {
|
||||
CallNode() { toAst(this) instanceof Py::Call }
|
||||
|
||||
/** Gets the underlying Python `Call`. */
|
||||
Py::Call getCall() { result = toAst(this) }
|
||||
|
||||
/** Gets the flow node for the function component of this call. */
|
||||
ControlFlowNode getFunction() {
|
||||
exists(Py::Call c |
|
||||
c = toAst(this) and
|
||||
c.getFunc() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
|
||||
/** Gets the flow node for the `n`th positional argument. */
|
||||
ControlFlowNode getArg(int n) {
|
||||
exists(Py::Call c |
|
||||
c = toAst(this) and
|
||||
c.getArg(n) = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
|
||||
/** Gets the flow node for the named argument with name `name`. */
|
||||
ControlFlowNode getArgByName(string name) {
|
||||
exists(Py::Call c, Py::Keyword k |
|
||||
c = toAst(this) and
|
||||
k = c.getANamedArg() and
|
||||
k.getValue() = toAst(result) and
|
||||
k.getArg() = name and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
|
||||
/** Gets a flow node corresponding to any argument. */
|
||||
ControlFlowNode getAnArg() { result = this.getArg(_) or result = this.getArgByName(_) }
|
||||
|
||||
/** Gets the first tuple (`*args`) argument, if any. */
|
||||
ControlFlowNode getStarArg() {
|
||||
exists(Py::Call c |
|
||||
c = toAst(this) and
|
||||
c.getStarArg() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
|
||||
/** Gets a dictionary (`**kwargs`) argument, if any. */
|
||||
ControlFlowNode getKwargs() {
|
||||
exists(Py::Call c |
|
||||
c = toAst(this) and
|
||||
c.getKwargs() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
|
||||
predicate isDecoratorCall() { this.isClassDecoratorCall() or this.isFunctionDecoratorCall() }
|
||||
|
||||
predicate isClassDecoratorCall() {
|
||||
exists(Py::ClassExpr cls | toAst(this) = cls.getADecoratorCall())
|
||||
}
|
||||
|
||||
predicate isFunctionDecoratorCall() {
|
||||
exists(Py::FunctionExpr func | toAst(this) = func.getADecoratorCall())
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to an attribute expression. */
|
||||
class AttrNode extends ControlFlowNode {
|
||||
AttrNode() { toAst(this) instanceof Py::Attribute }
|
||||
|
||||
/** Gets the flow node for the object of the attribute expression. */
|
||||
ControlFlowNode getObject() {
|
||||
exists(Py::Attribute a |
|
||||
a = toAst(this) and
|
||||
a.getObject() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
|
||||
/** Gets the flow node for the object of this attribute expression, with the matching name. */
|
||||
ControlFlowNode getObject(string name) {
|
||||
exists(Py::Attribute a |
|
||||
a = toAst(this) and
|
||||
a.getObject() = toAst(result) and
|
||||
a.getName() = name and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
|
||||
/** Gets the attribute name. */
|
||||
string getName() { exists(Py::Attribute a | a = toAst(this) and a.getName() = result) }
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to an import statement (`import x`). */
|
||||
class ImportExprNode extends ControlFlowNode {
|
||||
ImportExprNode() { toAst(this) instanceof Py::ImportExpr }
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a `from ... import name` expression. */
|
||||
class ImportMemberNode extends ControlFlowNode {
|
||||
ImportMemberNode() { toAst(this) instanceof Py::ImportMember }
|
||||
|
||||
/** Gets the flow node for the module being imported from, with the matching name. */
|
||||
ControlFlowNode getModule(string name) {
|
||||
exists(Py::ImportMember i |
|
||||
i = toAst(this) and
|
||||
i.getModule() = toAst(result) and
|
||||
i.getName() = name and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a `from ... import *` statement. */
|
||||
class ImportStarNode extends ControlFlowNode {
|
||||
ImportStarNode() { toAst(this) instanceof Py::ImportStar }
|
||||
|
||||
/** Gets the flow node for the module being imported from. */
|
||||
ControlFlowNode getModule() {
|
||||
exists(Py::ImportStar i |
|
||||
i = toAst(this) and
|
||||
i.getModuleExpr() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a subscript expression. */
|
||||
class SubscriptNode extends ControlFlowNode {
|
||||
SubscriptNode() { toAst(this) instanceof Py::Subscript }
|
||||
|
||||
/** Gets the flow node for the value being subscripted. */
|
||||
ControlFlowNode getObject() {
|
||||
exists(Py::Subscript s |
|
||||
s = toAst(this) and
|
||||
s.getObject() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
|
||||
/** Gets the flow node for the index expression. */
|
||||
ControlFlowNode getIndex() {
|
||||
exists(Py::Subscript s |
|
||||
s = toAst(this) and
|
||||
s.getIndex() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a comparison operation. */
|
||||
class CompareNode extends ControlFlowNode {
|
||||
CompareNode() { toAst(this) instanceof Py::Compare }
|
||||
|
||||
/** Holds if `left` and `right` are a pair of operands for this comparison. */
|
||||
predicate operands(ControlFlowNode left, Py::Cmpop op, ControlFlowNode right) {
|
||||
exists(Py::Compare c, Py::Expr eleft, Py::Expr eright |
|
||||
c = toAst(this) and eleft = toAst(left) and eright = toAst(right)
|
||||
|
|
||||
eleft = c.getLeft() and eright = c.getComparator(0) and op = c.getOp(0)
|
||||
or
|
||||
exists(int i |
|
||||
eleft = c.getComparator(i - 1) and eright = c.getComparator(i) and op = c.getOp(i)
|
||||
)
|
||||
) and
|
||||
left.getBasicBlock().dominates(this.getBasicBlock()) and
|
||||
right.getBasicBlock().dominates(this.getBasicBlock())
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a conditional expression (`x if c else y`). */
|
||||
class IfExprNode extends ControlFlowNode {
|
||||
IfExprNode() { toAst(this) instanceof Py::IfExp }
|
||||
|
||||
/** Gets the flow node for one of the operands of an if-expression. */
|
||||
ControlFlowNode getAnOperand() { result = this.getAPredecessor() }
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to an assignment expression (walrus `:=`). */
|
||||
class AssignmentExprNode extends ControlFlowNode {
|
||||
AssignmentExprNode() { toAst(this) instanceof Py::AssignExpr }
|
||||
|
||||
/** Gets the flow node for the left-hand side. */
|
||||
ControlFlowNode getTarget() {
|
||||
exists(Py::AssignExpr a |
|
||||
a = toAst(this) and
|
||||
a.getTarget() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
|
||||
/** Gets the flow node for the right-hand side. */
|
||||
ControlFlowNode getValue() {
|
||||
exists(Py::AssignExpr a |
|
||||
a = toAst(this) and
|
||||
a.getValue() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a binary expression (`a + b` etc.). */
|
||||
class BinaryExprNode extends ControlFlowNode {
|
||||
BinaryExprNode() { toAst(this) instanceof Py::BinaryExpr }
|
||||
|
||||
ControlFlowNode getLeft() {
|
||||
exists(Py::BinaryExpr be |
|
||||
be = toAst(this) and
|
||||
be.getLeft() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
|
||||
ControlFlowNode getRight() {
|
||||
exists(Py::BinaryExpr be |
|
||||
be = toAst(this) and
|
||||
be.getRight() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
|
||||
Py::Operator getOp() { result = toAst(this).(Py::BinaryExpr).getOp() }
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a boolean expression (`a and b`, `a or b`). */
|
||||
class BoolExprNode extends ControlFlowNode {
|
||||
BoolExprNode() { toAst(this) instanceof Py::BoolExpr }
|
||||
|
||||
Py::Boolop getOp() { result = toAst(this).(Py::BoolExpr).getOp() }
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a unary expression (`-x`, `not x`, etc.). */
|
||||
class UnaryExprNode extends ControlFlowNode {
|
||||
UnaryExprNode() { toAst(this) instanceof Py::UnaryExpr }
|
||||
|
||||
ControlFlowNode getOperand() {
|
||||
exists(Py::UnaryExpr u |
|
||||
u = toAst(this) and
|
||||
u.getOperand() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
|
||||
Py::Unaryop getOp() { result = toAst(this).(Py::UnaryExpr).getOp() }
|
||||
}
|
||||
|
||||
/**
|
||||
* A control flow node that is a definition: it appears in a context that
|
||||
* binds a variable (assignment target, parameter, etc.).
|
||||
*/
|
||||
class DefinitionNode extends ControlFlowNode {
|
||||
DefinitionNode() { this.isStore() or this.isParameter() }
|
||||
|
||||
/** Gets the value assigned, if any. */
|
||||
ControlFlowNode getValue() {
|
||||
exists(Py::Expr target, Py::Expr value |
|
||||
target = toAst(this) and
|
||||
value = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
|
|
||||
// x = value
|
||||
exists(Py::Assign a | a.getATarget() = target and a.getValue() = value)
|
||||
or
|
||||
// x = y = value (nested chained-assign target)
|
||||
exists(Py::Assign a | a.getATarget().(Py::Tuple).getElt(_) = target and a.getValue() = value)
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a deletion (`del x`). */
|
||||
class DeletionNode extends ControlFlowNode {
|
||||
DeletionNode() { this.isDelete() }
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a `for` loop target. */
|
||||
class ForNode extends ControlFlowNode {
|
||||
ForNode() { exists(Py::For f | toAst(this) = f.getIter()) }
|
||||
|
||||
/** Gets the iterable expression. */
|
||||
ControlFlowNode getIter() {
|
||||
result = this and result = result // canonical "after" of the iterable
|
||||
}
|
||||
|
||||
/** Gets the target (loop variable) of the `for` loop. */
|
||||
ControlFlowNode getTarget() {
|
||||
exists(Py::For f |
|
||||
f.getIter() = toAst(this) and
|
||||
f.getTarget() = toAst(result)
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a `raise` statement. */
|
||||
class RaiseStmtNode extends ControlFlowNode {
|
||||
RaiseStmtNode() { toAst(this) instanceof Py::Raise }
|
||||
|
||||
/** Gets the exception expression, if any. */
|
||||
ControlFlowNode getException() {
|
||||
exists(Py::Raise r |
|
||||
r = toAst(this) and
|
||||
r.getException() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a starred expression (`*x`). */
|
||||
class StarredNode extends ControlFlowNode {
|
||||
StarredNode() { toAst(this) instanceof Py::Starred }
|
||||
|
||||
/** Gets the value being starred. */
|
||||
ControlFlowNode getValue() {
|
||||
exists(Py::Starred s |
|
||||
s = toAst(this) and
|
||||
s.getValue() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to an `except` clause's name binding. */
|
||||
class ExceptFlowNode extends ControlFlowNode {
|
||||
ExceptFlowNode() { exists(Py::ExceptStmt e | toAst(this) = e.getName()) }
|
||||
|
||||
/** Gets the type expression of this exception handler. */
|
||||
ControlFlowNode getType() {
|
||||
exists(Py::ExceptStmt e |
|
||||
e.getName() = toAst(this) and
|
||||
e.getType() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to an `except*` clause's name binding. */
|
||||
class ExceptGroupFlowNode extends ControlFlowNode {
|
||||
ExceptGroupFlowNode() { exists(Py::ExceptGroupStmt e | toAst(this) = e.getName()) }
|
||||
}
|
||||
|
||||
/** Abstract base class for sequence nodes (tuple, list). */
|
||||
abstract class SequenceNode extends ControlFlowNode {
|
||||
/** Gets the `n`th element of this sequence. */
|
||||
abstract ControlFlowNode getElement(int n);
|
||||
|
||||
/** Gets any element of this sequence. */
|
||||
ControlFlowNode getAnElement() { result = this.getElement(_) }
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a tuple literal. */
|
||||
class TupleNode extends SequenceNode {
|
||||
TupleNode() { toAst(this) instanceof Py::Tuple }
|
||||
|
||||
override ControlFlowNode getElement(int n) {
|
||||
exists(Py::Tuple t |
|
||||
t = toAst(this) and
|
||||
t.getElt(n) = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a list literal. */
|
||||
class ListNode extends SequenceNode {
|
||||
ListNode() { toAst(this) instanceof Py::List }
|
||||
|
||||
override ControlFlowNode getElement(int n) {
|
||||
exists(Py::List l |
|
||||
l = toAst(this) and
|
||||
l.getElt(n) = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a set literal. */
|
||||
class SetNode extends ControlFlowNode {
|
||||
SetNode() { toAst(this) instanceof Py::Set }
|
||||
|
||||
/** Gets the flow node for an element of the set. */
|
||||
ControlFlowNode getAnElement() {
|
||||
exists(Py::Set s |
|
||||
s = toAst(this) and
|
||||
s.getAnElt() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to a dict literal. */
|
||||
class DictNode extends ControlFlowNode {
|
||||
DictNode() { toAst(this) instanceof Py::Dict }
|
||||
|
||||
/** Gets the flow node for a value of the dict. */
|
||||
ControlFlowNode getAValue() {
|
||||
exists(Py::Dict d |
|
||||
d = toAst(this) and
|
||||
d.getAValue() = toAst(result) and
|
||||
result.getBasicBlock().dominates(this.getBasicBlock())
|
||||
)
|
||||
}
|
||||
}
|
||||
|
||||
/** A control flow node corresponding to an iterable in a `for` loop. */
|
||||
class IterableNode extends ControlFlowNode {
|
||||
IterableNode() {
|
||||
exists(Py::For f | toAst(this) = f.getIter())
|
||||
or
|
||||
exists(Py::Comp c | toAst(this) = c.getIterable())
|
||||
}
|
||||
}
|
||||
Reference in New Issue
Block a user