On Wed, Mar 04, 2026 at 06:15:53PM +0300, Nazir Bilal Yavuz wrote:
> +#ifndef USE_NO_SIMD
> +static bool CopyReadLineTextSIMDHelper(CopyFromState cstate, bool is_csv,
> + bool
> *temp_hit_eof, int *temp_input_buf_ptr);
> +#endif
Should we inline this, too?
> + /*
> + * Do not disable SIMD when we hit EOL or EOF
> characters. In
> + * practice, it does not matter for EOF because
> parsing ends
> + * there, but we keep the behavior consistent.
> + */
> + if (!(simd_hit_eof || simd_hit_eol))
> + cstate->simd_enabled = false;
nitpick: I would personally avoid disabling it for EOF. It probably
doesn't amount to much, but I don't see any point in the extra
complexity/work solely for consistency.
> + /*
> + * We encountered a EOL or EOF on the first
> vector. This means
> + * lines are not long enough to skip fully
> sized vector. If
> + * this happens two times consecutively, then
> disable the
> + * SIMD.
> + */
> + if (first_vector)
> + {
> + if (cstate->simd_failed_first_vector)
> + cstate->simd_enabled = false;
> +
> + cstate->simd_failed_first_vector = true;
> + }
The first time I saw this, my mind immediately went to the extreme case
where this likely regresses: alternating long and short lines. We might
just want to disable it the first time we see a short line, like we do for
special characters. This is another thing that we can improve
independently later on.
> + /* First try to run SIMD, then continue with the scalar path */
> + if (cstate->simd_enabled)
> + {
> + int temp_input_buf_ptr = input_buf_ptr;
> + bool temp_hit_eof = false;
> +
> + result = CopyReadLineTextSIMDHelper(cstate, is_csv,
> &temp_hit_eof,
> +
> &temp_input_buf_ptr);
> + input_buf_ptr = temp_input_buf_ptr;
> + hit_eof = temp_hit_eof;
Given CopyReadLineTextSIMDHelper() doesn't have too much duplicated code,
moving the SIMD stuff to its own function is nice. The temp variables seem
a bit too magical to me, though. If those really make a difference, IMHO
there ought to be a big comment explaining why.
--
nathan
