Re: [Qemu-devel] [PATCH for-4.1 v2 35/36] tcg/aarch64: Use LDP to load tlb mask+table

[Peter Maydell]

On Thu, 28 Mar 2019 at 23:29, Richard Henderson
<address@hidden> wrote:
>
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  tcg/aarch64/tcg-target.inc.c | 9 +++------
>  1 file changed, 3 insertions(+), 6 deletions(-)
>
> diff --git a/tcg/aarch64/tcg-target.inc.c b/tcg/aarch64/tcg-target.inc.c
> index ac765137ae..979efbcfe4 100644
> --- a/tcg/aarch64/tcg-target.inc.c
> +++ b/tcg/aarch64/tcg-target.inc.c
> @@ -1463,14 +1463,11 @@ static void tcg_out_tlb_read(TCGContext *s, TCGReg 
> addr_reg, TCGMemOp opc,
>                               tcg_insn_unit **label_ptr, int mem_index,
>                               bool is_read)
>  {
> -    int fast_ofs = TLB_MASK_TABLE_OFS(mem_index);
> -    int mask_ofs = fast_ofs + offsetof(CPUTLBDescFast, mask);
> -    int table_ofs = fast_ofs + offsetof(CPUTLBDescFast, table);
>      unsigned a_bits = get_alignment_bits(opc);
>      unsigned s_bits = opc & MO_SIZE;
>      unsigned a_mask = (1u << a_bits) - 1;
>      unsigned s_mask = (1u << s_bits) - 1;
> -    TCGReg mask_base = TCG_AREG0, table_base = TCG_AREG0, x3;
> +    TCGReg x3;
>      TCGType mask_type;
>      uint64_t compare_mask;
>
> @@ -1478,8 +1475,8 @@ static void tcg_out_tlb_read(TCGContext *s, TCGReg 
> addr_reg, TCGMemOp opc,
>                   ? TCG_TYPE_I64 : TCG_TYPE_I32);
>
>      /* Load tlb_mask[mmu_idx] and tlb_table[mmu_idx].  */

The field names in this comment are out of date, I think ?

> -    tcg_out_ld(s, mask_type, TCG_REG_X0, mask_base, mask_ofs);
> -    tcg_out_ld(s, TCG_TYPE_PTR, TCG_REG_X1, table_base, table_ofs);
> +    tcg_out_insn(s, 3314, LDP, TCG_REG_X0, TCG_REG_X1, TCG_AREG0,
> +                 TLB_MASK_TABLE_OFS(mem_index), 1, 0);

Can we have a compile time assert somewhere that the
mask and table fields are at the offsets in CPUTLBDescFast
that we expect them to be?

thanks
-- PMM