Re: Re: [PATCH 2/2] [V3] [RISC-V] support cm.push cm.pop cm.popret in zcmp

[jiawei@iscas.ac.cn]

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 Sorry for the late,  I will send the binutils patch within this week.


----- Original Message -----
From: "Kito Cheng"
To: "Fei Gao"
Cc: gcc-patches@gcc.gnu.org, palmer@dabbelt.com, jeffreyalaw@gmail.com, sinan.lin@linux.alibaba.com, jiawei@iscas.ac.cn
Sent: Mon, 5 Jun 2023 16:31:29 +0800
Subject: Re: [PATCH 2/2] [V3] [RISC-V] support cm.push cm.pop cm.popret in zcmp

Only a few minor comments, otherwise LGTM :)

But I guess we need to wait until binutils merge zc stuff.

> Zcmp can share the same logic as save-restore in stack allocation: pre-allocation
> by cm.push, step 1 and step 2.
>
> please be noted cm.push pushes ra, s0-s11 in reverse order than what save-restore does.
> So adaption has been done in .cfi directives in my patch.
>
> Signed-off-by: Fei Gao
>
> gcc/ChangeLog:
>
> * config/riscv/iterators.md (-8): slot offset in bytes
> (-16): likewise
> (-24): likewise
> (-32): likewise
> (-40): likewise
> (-48): likewise
> (-56): likewise
> (-64): likewise
> (-72): likewise
> (-80): likewise
> (-88): likewise
> (-96): likewise
> (-104): likewise

Use slot0_offset...slot12_offset.

> @@ -422,6 +430,16 @@ static const struct riscv_tune_info riscv_tune_info_table[] = {
> #include "riscv-cores.def"
> };
>
> +typedef enum
> +{
> + PUSH_IDX = 0,
> + POP_IDX,
> + POPRET_IDX,
> + ZCMP_OP_NUM
> +} op_idx;

op_idx -> riscv_zcmp_op_t
> @@ -5388,6 +5487,42 @@ riscv_adjust_libcall_cfi_prologue ()
> return dwarf;
> }
>
> +static rtx
> +riscv_adjust_multi_push_cfi_prologue (int saved_size)
> +{
> + rtx dwarf = NULL_RTX;
> + rtx adjust_sp_rtx, reg, mem, insn;
> + unsigned int mask = cfun->machine->frame.mask;
> + int offset;
> + int saved_cnt = 0;
> +
> + if (mask & S10_MASK)
> + mask |= S11_MASK;
> +
> + for (int regno = GP_REG_LAST; regno >= GP_REG_FIRST; regno--)
> + if (BITSET_P (mask & MULTI_PUSH_GPR_MASK, regno - GP_REG_FIRST))
> + {
> + /* The save order is s11-s0, ra
> + from high to low addr. */
> + offset = saved_size - UNITS_PER_WORD * (++saved_cnt);
> +
> + reg = gen_rtx_REG (SImode, regno);

Should be Pmode rather than SImode, and seems
riscv_adjust_libcall_cfi_prologue has same issue...could you send a
separate patch to fix that?

> + mem = gen_frame_mem (SImode, plus_constant (Pmode,

Same here.

> + stack_pointer_rtx,
> + offset));
> +
> + insn = gen_rtx_SET (mem, reg);
> + dwarf = alloc_reg_note (REG_CFA_OFFSET, insn, dwarf);
> + }
> +
> + /* Debug info for adjust sp. */
> + adjust_sp_rtx = gen_rtx_SET (stack_pointer_rtx,
> + plus_constant(Pmode, stack_pointer_rtx, -saved_size));
> + dwarf = alloc_reg_note (REG_CFA_ADJUST_CFA, adjust_sp_rtx,
> + dwarf);
> + return dwarf;
> +}
> +
> static void
> riscv_emit_stack_tie (void)
> {


> @@ -5493,6 +5697,32 @@ riscv_expand_prologue (void)
> }
> }
>
> +static rtx
> +riscv_adjust_multi_pop_cfi_epilogue (int saved_size)
> +{
> + rtx dwarf = NULL_RTX;
> + rtx adjust_sp_rtx, reg;
> + unsigned int mask = cfun->machine->frame.mask;
> +
> + if (mask & S10_MASK)
> + mask |= S11_MASK;
> +
> + /* Debug info for adjust sp. */
> + adjust_sp_rtx = gen_rtx_SET (stack_pointer_rtx,
> + plus_constant(Pmode, stack_pointer_rtx, saved_size));
> + dwarf = alloc_reg_note (REG_CFA_ADJUST_CFA, adjust_sp_rtx,
> + dwarf);
> +
> + for (int regno = GP_REG_FIRST; regno <= GP_REG_LAST; regno++)
> + if (BITSET_P (mask, regno - GP_REG_FIRST))
> + {
> + reg = gen_rtx_REG (SImode, regno);

Pmode

> + dwarf = alloc_reg_note (REG_CFA_RESTORE, reg, dwarf);
> + }
> +
> + return dwarf;
> +}
> +
> static rtx
> riscv_adjust_libcall_cfi_epilogue ()
> {

> diff --git a/gcc/config/riscv/zc.md b/gcc/config/riscv/zc.md
> new file mode 100644
> index 00000000000..f2f2198598c
> --- /dev/null
> +++ b/gcc/config/riscv/zc.md
> @@ -0,0 +1,1042 @@
> +;; Machine description for RISC-V Zc extention.
> +;; Copyright (C) 2011-2023 Free Software Foundation, Inc.

2023 rather than 2011-2023