ARM setjmp and r12

[Nick Clifton]

Hi Shaun,

> On the ARM, why does setjmp preserve r12 (ip)?  I believe r12 is
> caller-preserved, not callee-preserved.
> 
> arm/setjmp.S:122
> 	/* Save all the callee-preserved registers into the jump buffer.  */
> 	stmea		a1!, { v1-v7, fp, ip, sp, lr }

I *think* that this is because GCC uses it as the static chain register 
for nested functions (when operating in ARM mode).

Cheers
   Nick