Hi, Jiufu
This definitely seems to be a better solution.
The TARGET_CONST_ANCHOR change should not be part of this patch. Also
there is no ChangeLog for the patch.
This generally looks correct and consistent with other ports. I want
to give Segher a chance to double check it, if he wishes.
Thanks David
On Mon, Jun 12, 2023 at 9:19 AM Jiufu Guo <guoji...@linux.ibm.com> wrote:
>
> Hi,
>
> For stack_tie, currently below insn is generated:
> (insn 15 14 16 3 (parallel [
> (set (mem/c:BLK (reg/f:DI 1 1) [1 A8])
> (const_int 0 [0]))
> ]) "/home/guojiufu/temp/gdb.c":13:3 922 {stack_tie}
> (nil))
>
> It is "set (mem/c:BLK (reg/f:DI 1 1) (const_int 0 [0])". This maybe
> looks like "a memory block is zerored", while actually stack_tie
> may be more like a placeholder, and does not generate any thing.
>
> To avoid potential misunderstand, "UNPSEC:BLK [(const_int 0)].." could
> be used here like other ports.
>
> This patch does this. Bootstrap®test pass on ppc64{,le}.
> Is this ok for trunk?
>
> BR,
> Jeff (Jiufu Guo)
>
> ---
> gcc/config/rs6000/predicates.md | 11 +++++++----
> gcc/config/rs6000/rs6000-logue.cc | 4 +++-
> gcc/config/rs6000/rs6000.cc | 4 ++++
> gcc/config/rs6000/rs6000.md | 14 ++++++++++----
> 4 files changed, 24 insertions(+), 9 deletions(-)
>
> diff --git a/gcc/config/rs6000/predicates.md b/gcc/config/rs6000/predicates.md
> index a16ee30f0c0..4748cb37ce8 100644
> --- a/gcc/config/rs6000/predicates.md
> +++ b/gcc/config/rs6000/predicates.md
> @@ -1854,10 +1854,13 @@ (define_predicate "stmw_operation"
> (define_predicate "tie_operand"
> (match_code "parallel")
> {
> - return (GET_CODE (XVECEXP (op, 0, 0)) == SET
> - && MEM_P (XEXP (XVECEXP (op, 0, 0), 0))
> - && GET_MODE (XEXP (XVECEXP (op, 0, 0), 0)) == BLKmode
> - && XEXP (XVECEXP (op, 0, 0), 1) == const0_rtx);
> + rtx set = XVECEXP (op, 0, 0);
> + return (GET_CODE (set) == SET
> + && MEM_P (SET_DEST (set))
> + && GET_MODE (SET_DEST (set)) == BLKmode
> + && GET_CODE (SET_SRC (set)) == UNSPEC
> + && XINT (SET_SRC (set), 1) == UNSPEC_TIE
> + && XVECEXP (SET_SRC (set), 0, 0) == const0_rtx);
> })
>
> ;; Match a small code model toc reference (or medium and large
> diff --git a/gcc/config/rs6000/rs6000-logue.cc
> b/gcc/config/rs6000/rs6000-logue.cc
> index bc6b153b59f..b99f43a8282 100644
> --- a/gcc/config/rs6000/rs6000-logue.cc
> +++ b/gcc/config/rs6000/rs6000-logue.cc
> @@ -1463,7 +1463,9 @@ rs6000_emit_stack_tie (rtx fp, bool hard_frame_needed)
> while (--i >= 0)
> {
> rtx mem = gen_frame_mem (BLKmode, regs[i]);
> - RTVEC_ELT (p, i) = gen_rtx_SET (mem, const0_rtx);
> + RTVEC_ELT (p, i)
> + = gen_rtx_SET (mem, gen_rtx_UNSPEC (BLKmode, gen_rtvec (1,
> const0_rtx),
> + UNSPEC_TIE));
> }
>
> emit_insn (gen_stack_tie (gen_rtx_PARALLEL (VOIDmode, p)));
> diff --git a/gcc/config/rs6000/rs6000.cc b/gcc/config/rs6000/rs6000.cc
> index d197c3f3289..0c81ebea711 100644
> --- a/gcc/config/rs6000/rs6000.cc
> +++ b/gcc/config/rs6000/rs6000.cc
> @@ -1760,6 +1760,10 @@ static const struct attribute_spec
> rs6000_attribute_table[] =
>
> #undef TARGET_UPDATE_IPA_FN_TARGET_INFO
> #define TARGET_UPDATE_IPA_FN_TARGET_INFO rs6000_update_ipa_fn_target_info
> +
> +#undef TARGET_CONST_ANCHOR
> +#define TARGET_CONST_ANCHOR 0x8000
> +
>
>
> /* Processor table. */
> diff --git a/gcc/config/rs6000/rs6000.md b/gcc/config/rs6000/rs6000.md
> index b0db8ae508d..fdcf8347812 100644
> --- a/gcc/config/rs6000/rs6000.md
> +++ b/gcc/config/rs6000/rs6000.md
> @@ -158,6 +158,7 @@ (define_c_enum "unspec"
> UNSPEC_HASHCHK
> UNSPEC_XXSPLTIDP_CONST
> UNSPEC_XXSPLTIW_CONST
> + UNSPEC_TIE
> ])
>
> ;;
> @@ -10828,7 +10829,9 @@ (define_expand "restore_stack_block"
> operands[4] = gen_frame_mem (Pmode, operands[1]);
> p = rtvec_alloc (1);
> RTVEC_ELT (p, 0) = gen_rtx_SET (gen_frame_mem (BLKmode, operands[0]),
> - const0_rtx);
> + gen_rtx_UNSPEC (BLKmode,
> + gen_rtvec (1, const0_rtx),
> + UNSPEC_TIE));
> operands[5] = gen_rtx_PARALLEL (VOIDmode, p);
> })
>
> @@ -10866,7 +10869,9 @@ (define_expand "restore_stack_nonlocal"
> operands[5] = gen_frame_mem (Pmode, operands[3]);
> p = rtvec_alloc (1);
> RTVEC_ELT (p, 0) = gen_rtx_SET (gen_frame_mem (BLKmode, operands[0]),
> - const0_rtx);
> + gen_rtx_UNSPEC (BLKmode,
> + gen_rtvec (1, const0_rtx),
> + UNSPEC_TIE));
> operands[6] = gen_rtx_PARALLEL (VOIDmode, p);
> })
>
> @@ -13898,7 +13903,8 @@ (define_insn "*save_fpregs_<mode>_r1"
> ; not be moved over loads from or stores to stack memory.
> (define_insn "stack_tie"
> [(match_parallel 0 "tie_operand"
> - [(set (mem:BLK (reg 1)) (const_int 0))])]
> + [(set (mem:BLK (reg 1))
> + (unspec:BLK [(const_int 0)] UNSPEC_TIE))])]
> ""
> ""
> [(set_attr "length" "0")])
> @@ -13910,7 +13916,7 @@ (define_insn "stack_restore_tie"
> [(set (match_operand:SI 0 "gpc_reg_operand" "=r,r")
> (plus:SI (match_operand:SI 1 "gpc_reg_operand" "r,r")
> (match_operand:SI 2 "reg_or_cint_operand" "O,rI")))
> - (set (mem:BLK (scratch)) (const_int 0))]
> + (set (mem:BLK (scratch)) (unspec:BLK [(const_int 0)] UNSPEC_TIE))]
> "TARGET_32BIT"
> "@
> mr %0,%1
> --
> 2.39.3
>
