On April 12, 2016 5:11:45 PM GMT+02:00, Richard Henderson <r...@redhat.com> wrote: >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.
Wouldn't that be quite expensive (building RTL)? Richard. > >r~
