Module DefinitionsAndUses

Import path

semmle.code.cpp.controlflow.DefinitionsAndUses

Imports

cpp

Provides classes and predicates for working with C/C++/ObjC/ObjC++ code.

Predicates

definition

Holds if def is a (potential) assignment to stack variable v. That is, the variable may hold another value in the control-flow node(s) following def than before.

definitionBarrier

Holds if barrier is either a (potential) definition of v or follows an access that gets the address of v. In both cases, the value of v after barrier cannot be assumed to be the same as before.

definitionByReference

Holds if va is a variable passed by reference as argument def, where the callee potentially assigns the corresponding parameter. The definitions-and-uses library models assignment by reference as if it happens on evaluation of the argument, def.

definitionReaches

Holds if the definition def of some stack variable can reach node, which is a definition or use, without crossing definitions of the same variable.

definitionUsePair

Computed relation: A “definition-use-pair” for a particular variable. Intuitively, this means that def is an assignment to var, and use is a read of var at which the value assigned by def may be read. (There can be more than one definition reaching a single use, and a single definition can reach many uses.)

exprDefinition

Holds if def is a (definite) assignment to the stack variable v. e is the assigned expression.

parameterUsePair

Holds if va is a use of the parameter p that could observe the passed-in value.

useOfVar

Holds if use is a non-definition use of stack variable v. This will not include accesses on the LHS of an assignment (which don’t retrieve the variable value), but will include accesses in increment/decrement operations.

useOfVarActual

Same as useOfVar(v, use), but with the extra condition that the access use actually reads the value of the stack variable v at run-time. (Non-examples include &x and function calls where the callee does not use the relevant parameter.)

useUsePair

A use/use pair is a pair of uses of a particular variable var where the same value might be read (meaning that there is a control-flow path from first to second without crossing a definition of var).

Classes

Def
DefOrUse

Utility class: A definition or use of a stack variable.

ParameterDef
Use