Monitoring Data Settings

The options described here provide monitoring of Intel compiler-generated code.

Specifying Structure Tag Alignments

You can specify an alignment constraint for structures and unions in two ways:

• Place a pack pragma in your source file, or
• Enter the alignment option on the command line

Both specifications change structure tag alignment constraints.

Flushing Denormal Values to Zero for Itanium-based Systems Only

Option -ftz flushes denormal results to zero when the application is in the gradual underflow mode. Use this option if the denormal values are not critical to application behavior. Flushing the denormal values to zero with -ftz may improve performance of your application. The default status of  -ftz is OFF. By default, the compiler lets results gradually underflow.

The -ftz switch only needs to be used on the source containing function main(). The effect of the -ftz switch is to turn on FTZ mode for the process started by main(). The initial thread and any threads subsequently created by that process will operate in FTZ mode.

Note

The -O3 option turns -ftz ON. Use -ftz- to disable flushing denormal results to zero.

Allocation of Zero-initialized Variables

By default, variables explicitly initialized with zeros are placed in the BSS section. But using the -nobss_init option, you can place any variables that are explicitly initialized with zeros in the DATA section if required.