CC uros.
On Mon, May 6, 2024 at 11:03 AM Kong, Lingling <lingling.k...@intel.com> wrote:
>
> Hi,
> (if_then_else:SI (eq (reg:CCZ 17 flags)
> (const_int 0 [0]))
> (reg/v:SI 101 [ e ])
> (reg:SI 102))
> The cost is 8 for the rtx, the cost for
> (eq (reg:CCZ 17 flags) (const_int 0 [0])) is 4, but this is just an operator
> do not need to compute it's cost in cmov.
It looks like a reasonable change to me, for cmov, the first operand
of if_then_else is not a mask.
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu.
> OK for trunk?
>
> gcc/ChangeLog:
>
> PR target/109549
> * config/i386/i386.cc (ix86_rtx_costs): The XEXP (x, 0) for cmov
> is an operator do not need to compute cost.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/cmov6.c: Fixed.
> ---
> gcc/config/i386/i386.cc | 2 +-
> gcc/testsuite/gcc.target/i386/cmov6.c | 5 +----
> 2 files changed, 2 insertions(+), 5 deletions(-)
>
> diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc index
> 4d6b2b98761..59b4ce3bfbf 100644
> --- a/gcc/config/i386/i386.cc
> +++ b/gcc/config/i386/i386.cc
> @@ -22237,7 +22237,7 @@ ix86_rtx_costs (rtx x, machine_mode mode, int
> outer_code_i, int opno,
> {
> /* cmov. */
> *total = COSTS_N_INSNS (1);
> - if (!REG_P (XEXP (x, 0)))
> + if (!COMPARISON_P (XEXP (x, 0)) && !REG_P (XEXP (x, 0)))
> *total += rtx_cost (XEXP (x, 0), mode, code, 0, speed);
> if (!REG_P (XEXP (x, 1)))
> *total += rtx_cost (XEXP (x, 1), mode, code, 1, speed); diff
> --git a/gcc/testsuite/gcc.target/i386/cmov6.c
> b/gcc/testsuite/gcc.target/i386/cmov6.c
> index 5111c8a9099..535326e4c2a 100644
> --- a/gcc/testsuite/gcc.target/i386/cmov6.c
> +++ b/gcc/testsuite/gcc.target/i386/cmov6.c
> @@ -1,9 +1,6 @@
> /* { dg-do compile } */
> /* { dg-options "-O2 -march=k8" } */
> -/* if-converting this sequence would require two cmov
> - instructions and seems to always cost more independent
> - of the TUNE_ONE_IF_CONV setting. */
> -/* { dg-final { scan-assembler-not "cmov\[^6\]" } } */
> +/* { dg-final { scan-assembler "cmov\[^6\]" } } */
>
> /* Verify that blocks are converted to conditional moves. */ extern int
> bar (int, int);
> --
> 2.31.1
>
--
BR,
Hongtao
