From: Richard Henderson <rth@twiddle.net>
To: Aurelien Jarno <aurelien@aurel32.net>
Cc: "Philippe Mathieu-Daudé" <f4bug@amsat.org>,
qemu-devel@nongnu.org, "Peter Maydell" <peter.maydell@linaro.org>,
qemu-arm@nongnu.org
Subject: Re: [Qemu-devel] [PATCH v3 2/5] target/arm: optimize rev16() using extract op
Date: Fri, 12 May 2017 12:05:00 -0700 [thread overview]
Message-ID: <aaa04be5-78d6-311b-609b-d02f18e9ef96@twiddle.net> (raw)
In-Reply-To: <20170512182132.jdw4g2pd5gvf2dti@aurel32.net>
On 05/12/2017 11:21 AM, Aurelien Jarno wrote:
> + uint64_t mask1 = sf ? 0x00ff00ff00ff00ffull : 0x00ff00ff;
> + uint64_t mask2 = sf ? 0xff00ff00ff00ff00ull : 0xff00ff00;
> +
> + tcg_gen_shri_i64(tcg_tmp, tcg_rn, 8);
> + tcg_gen_andi_i64(tcg_tmp, tcg_tmp, mask1);
> + tcg_gen_shli_i64(tcg_rd, tcg_rn, 8);
> + tcg_gen_andi_i64(tcg_rd, tcg_rd, mask2);
It would probably be better to use a single mask, since they're not free to
instantiate in a register. So e.g.
TCGv mask = tcg_const_i64(sf ? 0x00ff00ff00ff00ffull : 0x00ff00ff);
tcg_gen_shri_i64(tcg_tmp, tcg_rn, 8);
tcg_gen_and_i64(tcg_rd, tcg_rn, mask);
tcg_gen_and_i64(tcg_tmp, tcg_tmp, mask);
tcg_gen_shli_i64(tcg_rd, tcg_rd, 8);
r~
next prev parent reply other threads:[~2017-05-12 19:05 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-05-12 3:35 [Qemu-devel] [PATCH v3 0/5] optimize various tcg_gen() functions using extract op Philippe Mathieu-Daudé
2017-05-12 3:35 ` [Qemu-devel] [RFC PATCH v3 1/5] coccinelle: add a script to optimize tcg op using tcg_gen_extract() Philippe Mathieu-Daudé
2017-05-12 3:41 ` Julia Lawall
2017-05-12 5:36 ` Philippe Mathieu-Daudé
2017-05-12 7:16 ` Julia Lawall
2017-05-12 7:39 ` SF Markus Elfring
2017-05-12 17:49 ` Eric Blake
2017-05-12 5:48 ` SF Markus Elfring
2017-05-12 11:00 ` SF Markus Elfring
2017-05-12 3:35 ` [Qemu-devel] [PATCH v3 2/5] target/arm: optimize rev16() using extract op Philippe Mathieu-Daudé
2017-05-12 16:50 ` Richard Henderson
2017-05-12 18:21 ` Aurelien Jarno
2017-05-12 19:05 ` Richard Henderson [this message]
2017-05-12 19:22 ` Aurelien Jarno
2017-05-12 19:38 ` Richard Henderson
2017-05-12 23:50 ` Philippe Mathieu-Daudé
2017-05-12 3:35 ` [Qemu-devel] [PATCH v3 3/5] target/m68k: optimize bcd_flags() " Philippe Mathieu-Daudé
2017-05-12 3:35 ` [Qemu-devel] [PATCH v3 4/5] target/ppc: using various functions " Philippe Mathieu-Daudé
2017-05-12 23:48 ` Philippe Mathieu-Daudé
2017-05-12 3:35 ` [Qemu-devel] [PATCH v3 5/5] target/sparc: optimize " Philippe Mathieu-Daudé
2017-05-12 23:49 ` Philippe Mathieu-Daudé
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