Date: Wed, 11 Mar 2026 15:42:38 -0500
From: Nathan Bossart <nathandbossart@gmail.com>
To: Nazir Bilal Yavuz <byavuz81@gmail.com>
Cc: Manni Wood <manni.wood@enterprisedb.com>, KAZAR Ayoub <ma_kazar@esi.dz>,
	Neil Conway <neil.conway@gmail.com>,
	Andrew Dunstan <andrew@dunslane.net>,
	Shinya Kato <shinya11.kato@gmail.com>,
	PostgreSQL-development <pgsql-hackers@postgresql.org>
Subject: Re: Speed up COPY FROM text/CSV parsing using SIMD
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On Wed, Mar 11, 2026 at 10:22:18PM +0300, Nazir Bilal Yavuz wrote:
> Here is v14 which is v13-0001 + v13-0002.

Thanks!  It's getting close.

> +		/*
> +		 * Temporary variables are used here instead of passing the actual
> +		 * variables (especially input_buf_ptr) directly to the helper. Taking
> +		 * the address of a local variable might force the compiler to
> +		 * allocate it on the stack rather than in a register.  Because
> +		 * input_buf_ptr is used heavily in the hot scalar path below, keeping
> +		 * it in a register is important for performance.
> +		 */
> +		int			temp_input_buf_ptr;
> +		bool		temp_hit_eof = hit_eof;

A few notes:

* Does using a temporary variable for hit_eof actually make a difference?
AFAICT that's only updated when loading more data.

* Does inlining the function produce the same results?

* Also, I'm curious what the usual benchmarks look like with and without
this hack for the latest patch.

-- 
nathan