ARM and Thumb floating-point build options (ARMv7 and later)

Mixed ARM/Thumb

Choose the option --fpu softvfp+vfpv3 to have the compiler generate mixed ARM/Thumb code.

When the option --fpu softvfp+vfpv3 is selected, all functions are compiled using software floating-point linkage. This means that floating-point arguments are passed to and returned from functions in ARM integer registers.

Software floating-point linkage enables you to link with generic libraries and legacy code that are themselves built with software floating-point linkage.

ARM only

Choose the options --arm --fpu vfpv3 to have the compiler generate ARM code only. This uses hardware VFP linkage.

Thumb only

Choose the options --thumb --fpu vfpv3 to have the compiler generate Thumb code for your entire program. The 32-bit Thumb instruction set supports VFP instructions. Therefore, there is no need to switch to ARM state to perform VFP operations. This uses hardware VFP linkage.

Note

This option is available only for ARMv7 processors with VFPv3, for example the Cortex-A8, where VFP is directly accessible from both the ARM and the 32-bit Thumb instruction set.

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