On Fri, May 26, 2023 at 8:44 PM Roger Sayle <ro...@nextmovesoftware.com> wrote:
>
>
> This patch enhances one of the optimizations in simplify_binary_operation_1
> to allow it to simplify RTL expressions in modes than HOST_WIDE_INT by
> replacing a use of HWI_COMPUTABLE_MODE_P and UINTVAL with wide_int.
>
> The motivating example is a pending x86_64 backend patch that produces
> the following RTL in combine:
>
> (and:TI (zero_extend:TI (reg:DI 89))
> (const_wide_int 0x0ffffffffffffffff))
>
> where the AND is redundant, as the mask, ~0LL, is DImode's MODE_MASK.
> There's already an optimization that catches this for narrower modes,
> transforming (and:HI (zero_extend:HI (reg:QI x)) (const_int 0xff))
> into (zero_extend:HI (reg:QI x)), but this currently only handles
> CONST_INT not CONST_WIDE_INT. Fixed by upgrading this transformation
> to use wide_int, specifically rtx_mode_t and wi::mask.
>
> This patch has been tested on x86_64-pc-linux-gnu with make bootstrap
> and make -k check, both with and without --target_board=unix{-m32}
> with no new failures. Ok for mainline?
OK.
Thanks,
Richard.
>
> 2023-05-23 Roger Sayle <ro...@nextmovesoftware.com>
>
> gcc/ChangeLog
> * simplify-rtx.cc (simplify_binary_operation_1) <AND>: Use wide-int
> instead of HWI_COMPUTABLE_MODE_P and UINTVAL in transformation of
> (and (extend X) C) as (zero_extend (and X C)), to also optimize
> modes wider than HOST_WIDE_INT.
>
>
> Thanks in advance,
> Roger
> --
>
