Replace a HWI_COMPUTABLE_MODE_P with wide-int in simplify-rtx.cc.
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Commit Message
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?
2023-05-23 Roger Sayle <roger@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
--
Comments
On Fri, May 26, 2023 at 8:44 PM Roger Sayle <roger@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 <roger@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
> --
>
@@ -3826,15 +3826,16 @@ simplify_context::simplify_binary_operation_1 (rtx_code code,
there are no nonzero bits of C outside of X's mode. */
if ((GET_CODE (op0) == SIGN_EXTEND
|| GET_CODE (op0) == ZERO_EXTEND)
- && CONST_INT_P (trueop1)
- && HWI_COMPUTABLE_MODE_P (mode)
- && (~GET_MODE_MASK (GET_MODE (XEXP (op0, 0)))
- & UINTVAL (trueop1)) == 0)
+ && CONST_SCALAR_INT_P (trueop1)
+ && is_a <scalar_int_mode> (mode, &int_mode)
+ && is_a <scalar_int_mode> (GET_MODE (XEXP (op0, 0)), &inner_mode)
+ && (wi::mask (GET_MODE_PRECISION (inner_mode), true,
+ GET_MODE_PRECISION (int_mode))
+ & rtx_mode_t (trueop1, mode)) == 0)
{
machine_mode imode = GET_MODE (XEXP (op0, 0));
- tem = simplify_gen_binary (AND, imode, XEXP (op0, 0),
- gen_int_mode (INTVAL (trueop1),
- imode));
+ tem = immed_wide_int_const (rtx_mode_t (trueop1, mode), imode);
+ tem = simplify_gen_binary (AND, imode, XEXP (op0, 0), tem);
return simplify_gen_unary (ZERO_EXTEND, mode, tem, imode);
}