On Tue, May 28, 2024 at 12:48 PM liuhongt <hongtao....@intel.com> wrote:
>
> > IMO, there is no need for CONST_INT_P condition, we should also allow
> > symbol_ref, label_ref and const (all allowed by
> > x86_64_immediate_operand predicate), these all decay to an immediate
> > value.
>
> Changed.
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> Ok for trunk.
>
> For MEM, rtx_cost iterates each subrtx, and adds up the costs,
> so for MEM (reg) and MEM (reg + 4), the former costs 5,
> the latter costs 9, it is not accurate for x86. Ideally
> address_cost should be used, but it reduce cost too much.
> So current solution is make constant disp as cheap as possible.
>
> gcc/ChangeLog:
>
> PR target/67325
> * config/i386/i386.cc (ix86_rtx_costs): Reduce cost of MEM (A
> + imm) to "cost of MEM (A)" + 1.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/pr67325.c: New test.
OK.
Thanks,
Uros.
> ---
> gcc/config/i386/i386.cc | 18 +++++++++++++++++-
> gcc/testsuite/gcc.target/i386/pr67325.c | 7 +++++++
> 2 files changed, 24 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/pr67325.c
>
> diff --git a/gcc/config/i386/i386.cc b/gcc/config/i386/i386.cc
> index 3e2a3a194f1..85d87b9f778 100644
> --- a/gcc/config/i386/i386.cc
> +++ b/gcc/config/i386/i386.cc
> @@ -22194,7 +22194,23 @@ ix86_rtx_costs (rtx x, machine_mode mode, int
> outer_code_i, int opno,
> /* An insn that accesses memory is slightly more expensive
> than one that does not. */
> if (speed)
> - *total += 1;
> + {
> + *total += 1;
> + rtx addr = XEXP (x, 0);
> + /* For MEM, rtx_cost iterates each subrtx, and adds up the costs,
> + so for MEM (reg) and MEM (reg + 4), the former costs 5,
> + the latter costs 9, it is not accurate for x86. Ideally
> + address_cost should be used, but it reduce cost too much.
> + So current solution is make constant disp as cheap as possible.
> */
> + if (GET_CODE (addr) == PLUS
> + && x86_64_immediate_operand (XEXP (addr, 1), Pmode))
> + {
> + *total += 1;
> + *total += rtx_cost (XEXP (addr, 0), Pmode, PLUS, 0, speed);
> + return true;
> + }
> + }
> +
> return false;
>
> case ZERO_EXTRACT:
> diff --git a/gcc/testsuite/gcc.target/i386/pr67325.c
> b/gcc/testsuite/gcc.target/i386/pr67325.c
> new file mode 100644
> index 00000000000..c3c1e4c5b4d
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr67325.c
> @@ -0,0 +1,7 @@
> +/* { dg-do compile { target { ! ia32 } } } */
> +/* { dg-options "-O2" } */
> +/* { dg-final { scan-assembler-not "(?:sar|shr)" } } */
> +
> +int f(long*l){
> + return *l>>32;
> +}
> --
> 2.31.1
>
