Some aliasing questions

[Richard Henderson]

On 04/11/2016 05:30 PM, Alan Modra wrote:
> Either way, when we split to
> 	set (reg tmp) (high (const (minus ((symbol_ref) (reg 2)))))
> 	.. mem (lo_sum (reg tmp) (const (minus ((symbol_ref) (reg 2)))))
> both high and lo_sum reference r2 and the linker could happily replace
> rtmp in the lo_sum insn with r2 when the high address is known to be
> zero.

It would be interesting to see if the r2 reference in fact gets picked up 
inside the const.  My first reaction is that I could imagine tracking skipping 
over it completely, since we've been promised that the expression is constant.

Alternately, perhaps alias.c should reuse the existing delegitimize_address 
hook, allowing it to look through your current unspecs.


r~