Floating-point Arithmetic Precision

Option

Description

Default

-fp_port
IA-32 only

Rounds floating-point results at assignments and casts. Some speed impact.

OFF

-IFP_fma[-]
Itanium(TM)-based systems

Enables/disables the contraction of floating-point multiply and add/subtract operations into a single operation.

-IFP_fma

-IPF_fp_speculationmode
Itanium(TM)-based systems

Sets the compiler to speculate on fp operations in one of the following modes:
fast: speculate on fp operations;
safe: speculate on fp operations only when it is safe;
strict: enables the compiler's speculation on floating-point operations preserving floating-point status in all situations; same as off in the current version.
off: disables fp speculation.

-IPF_fpc64_
speculationfast

-IPF_flt_eval_method0

-IPF_flt_eval_method0 directs the compiler to evaluate the expressions involving floating-point operands in the precision indicated by the program. (-IPF_flt_eval_method2 is not supported in the current version.)

OFF

-IFP_fltacc[-]

Enables/disables the compiler to apply optimizations that affect floating-point accuracy. By default, the compiler may apply optimizations that affect floating-point accuracy.
-IPF_fltacc- disables such optimizations.
-IPF_fltacc- is effective when -mp is on.

-IFP_fltacc

-mp
 

Maintains declared precision and ensures that floating-point arithmetic conforms more closely to the ANSI and IEEE 754 standards. See details in the Maintaining and Restricting FP Arithmetic Precision.

OFF

-mp1

Restricts floating-point precision to be closer to declared precision. Some speed impact, but less than -mp. See details in the Maintaining and Restricting FP Arithmetic Precision.

OFF

-pc{32|64|80}
IA-32 only
 

Enables floating-point significand precision control as follows:
-pc32 to 24-bit significand
-pc64 to 53-bit significand (Default)
-pc80 to 64-bit significand  

-pc64

-prec_div
IA-32 only

Imroves the floating point division-to-multiplication optimization; may impact speed.

OFF

-rcd
IA-32 only

Enables efficient float-to-integer conversion.

OFF