TMS320F280049C: Build warning about EABI and COFF

Hi,

My customer encountered a warning when building the project. The warning is as follow:

advice: (Performance) EABI double

          precision is 64-bits as opposed to 32-bits for COFF. Consider

          changing doubles to floats for improved performance in FPU32-mode.

They set float_support=fpu32 in compile configuration of Makefile.

For example：  sint32_t is long (data type)

sint32_t PWM_frequency；

PWM_frequency = _IQ10(MAX_FREQ);

when MAX_FREQ=72345，there is no warning.

sint32_t PWM_frequency；

sint32_t  abc;

PWM_frequency = _IQ10(abc);

when abc=72345，there is a warning.

sint32_t PWM_frequency；

sint32_t  abc;

PWM_frequency = abc<<10;

when abc=72345，there is no warning.

The question is why there is a warning? How to eliminate the warning? Could you provide user guide of  EABI and COFF?

Thanks a lot!