fnsplit, Qfnsplit

Enables function splitting.

Syntax

Linux:

-fnsplit[=n]

-no-fnsplit

macOS:

None

Windows:

/Qfnsplit[:n]

/Qfnsplit-

Arguments

n

Is an optional positive integer indicating the threshold number.

The blocks can be placed into a different code segment if they are only reachable via a conditional branch whose taken probability is less than the specified n. Branch taken probability is heuristically calculated by the compiler and can be observed in assembly listings.

The range for n is 0 <= n <= 100.

Default

OFF	Function splitting is not enabled. However, function grouping is still enabled.

Description

This option enables function splitting. If you specify [Q]fnsplit with no n, you must also specify option [Q]prof-use, or the option will have no effect and no function splitting will occur.

If you specify n, function splitting is enabled and you do not need to specify option [Q]prof-use.

To disable function splitting when you use option [Q]prof-use, specify /Qfnsplit- (Windows*) or -no-fnsplit (Linux*).

Note

Function splitting is generally not supported when exception handling is turned on for C/C++ routines in the stack of called routines. See also -fexceptions (Linux*).

IDE Equivalent

None

Alternate Options

Linux: -freorder-blocks-and-partition (a gcc option)

Windows: None