fma, Qfma

Determines whether the compiler generates fused multiply-add (FMA) instructions if such instructions exist on the target processor.

IDE Equivalent

None

Architectures

All

Syntax

Linux and OS X:

-fma

-no-fma

Windows:

/Qfma

/Qfma-

Arguments

None

Default

-fma
or/Qfma

If the instructions exist on the target processor, the compiler generates fused multiply-add (FMA) instructions.

However, if you specify -fp-model strict (Linux* OS and OS X*) or /fp:strict (Windows* OS), but do not explicitly specify -fma or /Qfma, the default is -no-fma or /Qfma-.

Description

This option determines whether the compiler generates fused multiply-add (FMA) instructions if such instructions exist on the target processor. When -fma (Linux OS and OS X) or /Qfma (Windows OS) is specified, the compiler may generate FMA instructions for combining multiply and add operations. When -no-fma (Linux OS and OS X) or /Qfma- (Windows OS) is specified, the compiler must generate separate multiply and add instructions with intermediate rounding.

This option has no effect unless setting CORE-AVX2 or higher is specified for option -x (Linux OS and OS X) or /Qx (Windows OS), or options -march (Linux OS and OS X) or /arch (Windows OS).