Subject: Re: AltiVec and *jmp.
To: Jason R Thorpe <>
From: Matt Thomas <>
List: tech-userlevel
Date: 07/02/2002 08:06:46
At 08:01 AM 7/2/2002, Jason R Thorpe wrote:
>On Tue, Jul 02, 2002 at 12:44:47AM -0700, Matt Thomas wrote:
>  > When AltiVec is present (__VEC__ is defined), the jmp_buf is
>  > extended by 48 bytes and vector registers are saved starting
>  > at offset 256 and the contents of VRSAVE are at offset 248.
>  >
>  > This requires a different setjmp/longjmp, etal so perform the
>  > optional altivec instructions.
>Actually, I'd say that you simply should not do this at all.  These
>routines don't save/restore FP state either, for example.

Except that the SVR4 ABI extentions for AltiVec mandate saving the
caller-saved AltiVec registers.  The question comes down to whether
we want to ABI-compliant.

Matt Thomas               Internet:
3am Software Foundry      WWW URL:
Cupertino, CA             Disclaimer: I avow all knowledge of this message