[committed,v2] RISC-V: Fix build errors with shNadd/shNadd.uw patterns in zba cost model

  Fix a build regression from commit 04a9b554ba1a ("RISC-V: Cost model 
for zba extension."):

.../gcc/config/riscv/riscv.c: In function 'bool riscv_rtx_costs(rtx, machine_mode, int, int, int*, bool)':
.../gcc/config/riscv/riscv.c:2018:11: error: 'and' of mutually exclusive equal-tests is always 0 [-Werror]
 2018 |           && IN_RANGE (INTVAL (XEXP (XEXP (x, 0), 0)), 1, 3))
      |           ^~
.../gcc/config/riscv/riscv.c:2047:17: error: unused variable 'ashift_lhs' [-Werror=unused-variable]
 2047 |             rtx ashift_lhs = XEXP (and_lhs, 0);
      |                 ^~~~~~~~~~


by correcting a CONST_INT_P check referring the wrong operand and 
getting rid of the unused variable.

	gcc/
	* config/riscv/riscv.c (riscv_rtx_costs): Correct a CONST_INT_P 
	check and remove an unused local variable with shNadd/shNadd.uw 
	pattern handling.
---
Hi Kito,

> I think that's my mistake...it should fix following check rather than
> remove the REG_P like that:
> 
> @@ -2014,8 +2014,8 @@ riscv_rtx_costs (rtx x, machine_mode mode, int
> outer_code, int opno ATTRIBUTE_UN
>              (TARGET_64BIT && (mode == DImode)))
>          && (GET_CODE (XEXP (x, 0)) == ASHIFT)
>          && REG_P (XEXP (XEXP (x, 0), 0))
> -         && CONST_INT_P (XEXP (XEXP (x, 0), 0))
> -         && IN_RANGE (INTVAL (XEXP (XEXP (x, 0), 0)), 1, 3))
> +         && CONST_INT_P (XEXP (XEXP (x, 0), 1))
> +         && IN_RANGE (INTVAL (XEXP (XEXP (x, 0), 1)), 1, 3))
>        {
>          *total = COSTS_N_INSNS (1);
>          return true;
> 
> 
> shNadd pattern:
> 
> (define_insn "*shNadd"
>  [(set (match_operand:X 0 "register_operand" "=r")
>        (plus:X (ashift:X (match_operand:X 1 "register_operand" "r")
>                          # What I want to check is here, it should be
> XEXP (XEXP (x, 0), 1)
>                          (match_operand:QI 2 "immediate_operand" "I"))
>                (match_operand:X 3 "register_operand" "r")))]

 Right, I should have cross-checked with the machine description.

 Also are we missing explicit test coverage here?  Or is it supposed to
be covered by the generic tests here or there already (I'm not familiar 
with the details of the ISA extension to tell offhand), as long as the 
extension has been enabled for the target tested, and it is just that 
the problem has slipped through somehow?

> Otherwise LGTM, feel free to commit once you address this issue.

 Rebuilt for verification and committed as shown.  Thank you for your 
review.

  Maciej
---
 gcc/config/riscv/riscv.c |    5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

gcc-riscv-rtx-costs-zba-shnadd.diff
  

On Wed, Nov 3, 2021 at 12:07 AM Maciej W. Rozycki <macro@embecosm.com> wrote:
>
> Fix a build regression from commit 04a9b554ba1a ("RISC-V: Cost model
> for zba extension."):
>
> .../gcc/config/riscv/riscv.c: In function 'bool riscv_rtx_costs(rtx, machine_mode, int, int, int*, bool)':
> .../gcc/config/riscv/riscv.c:2018:11: error: 'and' of mutually exclusive equal-tests is always 0 [-Werror]
>  2018 |           && IN_RANGE (INTVAL (XEXP (XEXP (x, 0), 0)), 1, 3))
>       |           ^~
> .../gcc/config/riscv/riscv.c:2047:17: error: unused variable 'ashift_lhs' [-Werror=unused-variable]
>  2047 |             rtx ashift_lhs = XEXP (and_lhs, 0);
>       |                 ^~~~~~~~~~
>
>
> by correcting a CONST_INT_P check referring the wrong operand and
> getting rid of the unused variable.
>
>         gcc/
>         * config/riscv/riscv.c (riscv_rtx_costs): Correct a CONST_INT_P
>         check and remove an unused local variable with shNadd/shNadd.uw
>         pattern handling.
> ---
> Hi Kito,
>
> > I think that's my mistake...it should fix following check rather than
> > remove the REG_P like that:
> >
> > @@ -2014,8 +2014,8 @@ riscv_rtx_costs (rtx x, machine_mode mode, int
> > outer_code, int opno ATTRIBUTE_UN
> >              (TARGET_64BIT && (mode == DImode)))
> >          && (GET_CODE (XEXP (x, 0)) == ASHIFT)
> >          && REG_P (XEXP (XEXP (x, 0), 0))
> > -         && CONST_INT_P (XEXP (XEXP (x, 0), 0))
> > -         && IN_RANGE (INTVAL (XEXP (XEXP (x, 0), 0)), 1, 3))
> > +         && CONST_INT_P (XEXP (XEXP (x, 0), 1))
> > +         && IN_RANGE (INTVAL (XEXP (XEXP (x, 0), 1)), 1, 3))
> >        {
> >          *total = COSTS_N_INSNS (1);
> >          return true;
> >
> >
> > shNadd pattern:
> >
> > (define_insn "*shNadd"
> >  [(set (match_operand:X 0 "register_operand" "=r")
> >        (plus:X (ashift:X (match_operand:X 1 "register_operand" "r")
> >                          # What I want to check is here, it should be
> > XEXP (XEXP (x, 0), 1)
> >                          (match_operand:QI 2 "immediate_operand" "I"))
> >                (match_operand:X 3 "register_operand" "r")))]
>
>  Right, I should have cross-checked with the machine description.
>
>  Also are we missing explicit test coverage here?  Or is it supposed to
> be covered by the generic tests here or there already (I'm not familiar
> with the details of the ISA extension to tell offhand), as long as the
> extension has been enabled for the target tested, and it is just that
> the problem has slipped through somehow?

Cost model is not easy to test (at least to me :p), I usually verify
that by check the dump of combine pass to make sure the cost is right.

> > Otherwise LGTM, feel free to commit once you address this issue.
>
>  Rebuilt for verification and committed as shown.  Thank you for your
> review.

Thanks!

>
>   Maciej
> ---
>  gcc/config/riscv/riscv.c |    5 ++---
>  1 file changed, 2 insertions(+), 3 deletions(-)
>
> gcc-riscv-rtx-costs-zba-shnadd.diff
> Index: gcc/gcc/config/riscv/riscv.c
> ===================================================================
> --- gcc.orig/gcc/config/riscv/riscv.c
> +++ gcc/gcc/config/riscv/riscv.c
> @@ -2014,8 +2014,8 @@ riscv_rtx_costs (rtx x, machine_mode mod
>               (TARGET_64BIT && (mode == DImode)))
>           && (GET_CODE (XEXP (x, 0)) == ASHIFT)
>           && REG_P (XEXP (XEXP (x, 0), 0))
> -         && CONST_INT_P (XEXP (XEXP (x, 0), 0))
> -         && IN_RANGE (INTVAL (XEXP (XEXP (x, 0), 0)), 1, 3))
> +         && CONST_INT_P (XEXP (XEXP (x, 0), 1))
> +         && IN_RANGE (INTVAL (XEXP (XEXP (x, 0), 1)), 1, 3))
>         {
>           *total = COSTS_N_INSNS (1);
>           return true;
> @@ -2044,7 +2044,6 @@ riscv_rtx_costs (rtx x, machine_mode mod
>             if (!CONST_INT_P (and_rhs))
>               break;
>
> -           rtx ashift_lhs = XEXP (and_lhs, 0);
>             rtx ashift_rhs = XEXP (and_lhs, 1);
>
>             if (!CONST_INT_P (ashift_rhs)
  

On Wed, 3 Nov 2021, Kito Cheng wrote:

> >  Also are we missing explicit test coverage here?  Or is it supposed to
> > be covered by the generic tests here or there already (I'm not familiar
> > with the details of the ISA extension to tell offhand), as long as the
> > extension has been enabled for the target tested, and it is just that
> > the problem has slipped through somehow?
> 
> Cost model is not easy to test (at least to me :p), I usually verify
> that by check the dump of combine pass to make sure the cost is right.

 Fair enough.  Note that intermediate dumps can be used for automatic 
verification too, with `scan-tree-dump', `scan-rtl-dump', etc. (I guess 
you probably knew that already).  I know that writing a good test case 
can be tricky.

  Maciej