On September 10, 2015 7:48:10 PM GMT+02:00, David Edelsohn <dje....@gmail.com> wrote: >On Thu, Sep 10, 2015 at 1:41 PM, Bill Schmidt ><wschm...@linux.vnet.ibm.com> wrote: >> Currently the little-endian swap optimization is disabled for >> computations that include vector permute instructions. We generate a >> vperm in a variety of ways, and for the most general cases, we can't >> replace a vperm with a swap-equivalent sequence without cost >modeling. >> However, the most common use of vperm is using an UNSPEC_VPERM where >the >> mask operand is loaded from the constant pool. For these cases, we >can >> optimize the computation provided that we change the loaded constant. >> This patch recognizes these cases and provides the necessary special >> handling. >> >> An abbreviated description of the general case being recognized is: >> >> (set (reg:DI A constant-pool-symbol)) >> (set (reg:V16QI B (swap (mem:V16QI (reg:DI A))))) ; lxvd2x >> (set (reg:V16QI C (swap (reg:V16QI B)))) ; xxpermdi >> (set (reg D (unspec [(reg X)(reg Y)(reg:V16QI C)] UNSPEC_VPERM))) >> >> where "swap" is a vec_select operation that performs a doubleword >swap. >> We adjust the mask to be used and create a new constant pool entry >for >> it, with a new MEM used to load it. The new MEM is substituted into >the >> load instruction, after which cleanup is done on the dataflow >> structures. >> >> I've added two new tests, one to verify that swaps are removed, and >one >> to verify that the vperm transformation produces correct results. >> >> Bootstrapped and tested on powerpc64le-unknown-linux-gnu with no >> regressions. Is this ok for trunk? > >Okay.
+ if (!toc_relative_expr_p (SET_SRC (PATTERN (tocrel_insn)), false)) + gcc_assert (0); Just curious if this isn't usually spelled as gcc_unreachable()? Both should end up as equally unlikely I suppose so just bikeshedding.. Thanks,
