When the #pragma altivec_vrsave directive is enabled, function prologs and epilogs include code to maintain the VRSAVE register.
.-on----. >>-#--pragma--altivec_vrsave--+-off---+------------------------>< '-allon-'
where pragma settings do the following:
on | Function prologs and epilogs include code to maintain the VRSAVE register. |
off | Function prologs and epilogs do not include code to maintain the VRSAVE register. |
allon | The function containing the altivec_vrsave pragma sets all bits of the VRSAVE register to 1, indicating that all vectors are used and should be saved if a context switch occurs. |
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