Floating-point Options for Itanium®-based Systems

The following table lists options that enable you to control the compiler optimizations for floating-point computations on Itanium®-based systems. The options listed here are not valid for IA-32 and Intel® EM64T systems.

Note

Mac OS*: The options listed in this topic are not supported.

Windows*	Linux*	Effect
/QIPF-fma	-IPF-fma	Enables or disables the contraction of floating-point multiply and add/subtract operations into a single operation. Unless -fp-model strict (Linux) or /fp:strict (Windows) is specified, the compiler contracts these operations whenever possible. The -fp-model strict (Linux) or /fp:strict (Windows) option disables the contractions. For example, a combination of -fp-model strict (Linux) or /fp:strict (Windows) and -IPF-fma (Linux) or /QIPF-fma (Windows) enables the compiler to contract operations: ifort -fp-model strict -IPF-fma myprog.f (Linux) ifort /fp:strict /QIPF-fma myprog.f (Windows) For more information, see the following topic: -IPF-fma compiler option
/QIPF-fp-speculation	-IPF-fp-speculation	Default. Sets the compiler to speculate on floating-point operations. When using the -fp-model strict or -fp-model except (Linux) or /fp:strict or /fp:except options, the speculation mode is set to strict and cannot be overridden; however, when using the -fp-model fast (Linux) or /fp:fast (Windows) option, you can use the -IPF-fp-speculation (Linux) or /QIPF-fp-speculation (Windows) option to restrict speculation. For more information, see the following topic: -IPF-fp-speculation compiler option
/QIPF-fp-relaxed	-IPF-fp-relaxed	Enables use of faster but slightly less accurate code sequences for math functions, such as the sqrt() function and the divide operation. As compared to strict IEEE* precision, using this option slightly reduces the accuracy of floating-point calculations performed by these functions, usually limited to the least significant digit. When using any -fp-model (Linux) or /fp (Windows) option setting, this option is disabled: -no-IPF-fp-relaxed (Linux) or /QIPF_fp_relaxed- (Windows); however, -fp-model (Linux) or /fp (Windows) does not override the explicit setting. For more information, see the following topic: -IPF-fp-relaxed compiler option

Windows*

Linux*

Effect

/QIPF-fma

-IPF-fma

Enables or disables the contraction of floating-point multiply and add/subtract operations into a single operation. Unless -fp-model strict (Linux) or /fp:strict (Windows) is specified, the compiler contracts these operations whenever possible. The -fp-model strict (Linux) or /fp:strict (Windows) option disables the contractions.

For example, a combination of -fp-model strict (Linux) or /fp:strict (Windows) and -IPF-fma (Linux) or /QIPF-fma (Windows) enables the compiler to contract operations:

ifort -fp-model strict -IPF-fma myprog.f (Linux)
ifort /fp:strict /QIPF-fma myprog.f (Windows)

For more information, see the following topic:

-IPF-fma compiler option

/QIPF-fp-speculation

-IPF-fp-speculation

Default. Sets the compiler to speculate on floating-point operations.

When using the -fp-model strict or -fp-model except (Linux) or /fp:strict or /fp:except options, the speculation mode is set to strict and cannot be overridden; however, when using the -fp-model fast (Linux) or /fp:fast (Windows) option, you can use the -IPF-fp-speculation (Linux) or /QIPF-fp-speculation (Windows) option to restrict speculation.

For more information, see the following topic:

-IPF-fp-speculation compiler option

/QIPF-fp-relaxed

-IPF-fp-relaxed

Enables use of faster but slightly less accurate code sequences for math functions, such as the sqrt() function and the divide operation. As compared to strict IEEE* precision, using this option slightly reduces the accuracy of floating-point calculations performed by these functions, usually limited to the least significant digit.

When using any -fp-model (Linux) or /fp (Windows) option setting, this option is disabled: -no-IPF-fp-relaxed (Linux) or /QIPF_fp_relaxed- (Windows); however, -fp-model (Linux) or /fp (Windows) does not override the explicit setting.

For more information, see the following topic:

-IPF-fp-relaxed compiler option