fp-speculation, Qfp-speculation

Tells the compiler the mode in which to speculate on floating-point operations.

Syntax

Linux and macOS:

-fp-speculation=mode

Windows:

/Qfp-speculation:mode

Arguments

mode

Is the mode for floating-point operations. Possible values are:

fast	Tells the compiler to speculate on floating-point operations.
safe	Tells the compiler to disable speculation if there is a possibility that the speculation may cause a floating-point exception.
strict	Tells the compiler to disable speculation on floating-point operations.
off	This is the same as specifying strict.

Default

-fp-speculation=fast
or/Qfp-speculation:fast

The compiler speculates on floating-point operations. This is also the behavior when optimizations are enabled. However, if you specify no optimizations (-O0 on Linux*; /Od on Windows*), the default is -fp-speculation=safe (Linux*) or /Qfp-speculation:safe (Windows*).

Description

This option tells the compiler the mode in which to speculate on floating-point operations.

Disabling speculation may prevent the vectorization of some loops containing conditionals. For an example, see the article titled: Diagnostic 15326: loop was not vectorized: implied FP exception model prevents vectorization, which is located in https://software.intel.com/en-us/articles/fdiag15326 .

IDE Equivalent

Visual Studio: Floating Point > Floating-Point Speculation

Eclipse: None

Xcode: Floating Point > Floating-Point Speculation

Alternate Options

None