setjmp on 32b MIPS with 64b FPRs

[Steve Ellcey]

On Sun, 2013-08-25 at 11:31 +0300, Yossi Kreinin wrote:
> Hi,
> 
> I'll talk to the person maintaining the newlib build in our company
> and we'll hopefully apply and test the patch together ASAP. In the
> meanwhile, a couple of questions:
> 
> 1. #ifdef __mips_fpr=64 - did you mean #if __mips_fpr == 64?

Yes, it should be '#if __mips_fpr == 64'.
> 
> 2. I'm guessing the definition of jmp_buf in setjmp.h would need
> fixing as well ("breaking" the ABI - in the sense that currently
> setjmp doesn't save doubles on 32b MIPSes with 64b floats, but perhaps
> that's good enough to work for some apps; and once jmp_buf is
> redefined to have enough space for saved 64b register values, those
> previously working apps would break because they were compiled with
> smaller jmp_bufs and now they're dynamically linked against a libc
> that expects larger jmp_bufs, overwriting whatever it was that those
> apps happened to place right after their jmp_bufs.) What's normally
> done about ABI-breaking fixes in MIPS's libc I don't know - I'm just
> guessing it might be a problem.

You are right, we would need to increase the size of jmp_buf.  I will
ask around to see if there is any consensus on what is the best solution
to this.

Steve Ellcey
sellcey@mips.com