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Global Variables in Polyspace Access Web Interface

This topic focuses on the Polyspace® Access web interface. To learn about the equivalent pane in the Polyspace desktop user interface, see Variable Access in Polyspace Desktop User Interface (Polyspace Code Prover).

The Global Variables pane displays global variables (and local static variables). For each global variable, the pane lists all functions and tasks performing read/write access on the variables, along with their attributes, such as values, read/write accesses and shared usage.

You open the Global Variables Usage pane by using the icon in your Results Details pane, or by going to Window > Global Variables Usage.

The Global Variables pane lists all global variables along with attributes such as possible range of values, number of read and write operations, and so on.

For each variable and each read/write access, the Global Variables Usage pane contains the relevant attributes. For the variables, the various attributes are listed in this table.

AttributeDescription
Variables

Name of Variable

Values

Value (or range of values) of variable

This column is empty for pointer variables.

# ReadsNumber of times the variable is read
# WritesNumber of times the variable is written
Read by taskName of tasks reading variable
Written by taskName of tasks writing on variable
Protection

Whether shared variable is protected from concurrent access

(Filled only when Usage column has entry, Shared)

The possible entries in this column are:

  • Critical Section: If variable is accessed in critical section of code

  • Temporal Exclusion: If variable is accessed in mutually exclusive tasks

For more details on these entries, see the documentation for Polyspace Code Prover™ or Polyspace Code Prover Server™.

UsageShared, if variable is shared between tasks; otherwise, blank
FileSource file containing variable declaration
Data TypeData type of variable (C/C++ data types or structures/classes)

Double-click a variable name to view read/write access operations on the variable in the Results Details pane. The arrowhead symbols and in the Results Details pane indicate functions performing read and write access respectively on the global variable. For further information on tasks, see analysis option Tasks (-entry points) in the documentation for Polyspace Code Prover or Polyspace Code Prover Server.

For access operations on the variables, the various attributes described in the Global Variables Usage pane are listed in this table.

AttributeDescription
Values

Value or range of values of variable in the function or task performing read/write access

This column is empty for pointer variables.

Written by taskOnly for tasks: Name of task performing write access on variable
Read by taskOnly for tasks: Name of task performing read access on variable
FileSource file containing access operation on variable

The Results Details pane also lists the Scope of the access operation on the variable.

For example, consider the global variable, SHR2:

The Result Details pane shows that the variable SHR2 is shared among several tasks and some of the operations on SHR2 are not protected against concurrent access. The Result Details pane also shows the possibly conflicting operations.

The function, Tserver, in the file, tasks1.c, performs two write operations on SHR2. This is indicated in the Results Details pane by the two instances of Tserver() in the table, marked by . Likewise, the read access by task initregulate is also listed in the table and marked by .

The color scheme for variables in the Global Variables Usage pane is:

  • Black: global variable.

  • Orange: global variable, shared between tasks with no protection against concurrent access.

  • Green: global variable, shared between tasks and protected against concurrent access.

  • Gray: global variable, declared but not used in reachable code.

If a task performs certain operations on a global variable, but the operations are in unreachable code, the tasks are colored gray.

The information about global variables and read/write access operations obtained from the Global Variables Usage pane is called the data dictionary.

You can also perform the following actions from the Global Variables Usage pane.

  •  View Structured Variables

  •  Show/Hide Callers and Callees

  •  Hide Access in Unreachable Code

  •  Limitations