Shift right on signed integers as arithmetic shift (-logical-signed-right-shift)

R2026b

Specify that your compiler implements right shifts on signed integers as arithmetic shifts

Since R2023b

Description

Specify that your compiler implements right shifts on signed integers as arithmetic shifts (sign bit preserved). Compilers typically implement right shifts on signed integers as arithmetic shift instead of logical shift.

If you clear this check box, Polyspace® assumes that your compiler performs logical right shifts on signed integers. This option is equivalent to the option Signed right shift (-logical-signed-right-shift).

Set Option

Set the option using one of these methods:

  • Polyspace Platform user interface (desktop products only): In your project configuration, on the Build tab, select the Target and Compiler node and then select this option.

  • Command line and options file: Use the option -logical-signed-right-shift. See Command-Line Information.

  • Python® API: Set the ArithmeticSignedIntegerRightShift property in the build configuration. See polyspace.project.BuildConfiguration (Polyspace Test).

  • TOML configuration file (.toml.pscfg) — Use the key ArithmeticSignedIntegerRightShift. For example:

    ArithmeticSignedIntegerRightShift = true

Why Use This Option

The C99 Standard (sec 6.5.7) states that for a right-shift operation x1>>x2, if x1 is signed and has negative values, the behavior is implementation-defined. Different compilers choose between arithmetic and logical shift. Use this option to emulate your compiler.

Settings

On (default)

This option indicates that the right shift is arithmetic. That is, during the shift, the sign bit remains:

(-4) >> 1 = -2
(-7) >> 1 = -4
  7  >> 1 = 3
Off

This option indicates that the right shift is logical. That is, 0 replaces the sign bit:

(-4) >> 1 = (-4U) >> 1 = 2147483646
(-7) >> 1 = (-7U) >> 1 = 2147483644
  7  >> 1 = 3

Command-Line Information

When using the command line, arithmetic is the default computation mode. When this option is set, logical computation is performed.

Parameter: -logical-signed-right-shift
Default: Arithmetic signed right shifts
Example (Bug Finder): polyspace-bug-finder -logical-signed-right-shift
Example (Code Prover): polyspace-code-prover -logical-signed-right-shift
Example (Bug Finder Server): polyspace-bug-finder-server -logical-signed-right-shift
Example (Code Prover Server): polyspace-code-prover-server -logical-signed-right-shift

Version History

Introduced in R2023b

See Also

(Polyspace Test)

Topics