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Re: [Qemu-devel] [PATCH] Fix bug in translation of REVSH
From: |
Aurelien Jarno |
Subject: |
Re: [Qemu-devel] [PATCH] Fix bug in translation of REVSH |
Date: |
Mon, 27 Dec 2010 19:57:49 +0100 |
User-agent: |
Mutt/1.5.20 (2009-06-14) |
On Mon, Oct 18, 2010 at 02:49:36PM +0200, Johan Bengtsson wrote:
> The translation of REVSH shifted the low byte 8 steps left before performing
> an 8-bit sign extend, causing this part of the expression to alwas be 0.
> The fix for this is either to extend before shifting or switch to a 16-bit
> extend. I choose the former.
>
> Signed-off-by: Johan Bengtsson <address@hidden>
> ---
> target-arm/translate.c | 2 +-
> 1 files changed, 1 insertions(+), 1 deletions(-)
Thanks for this patch. While it is correct, I have committed a different
fix using tcg_gen_bswap16, so that the generated code can be optimized
on some hosts.
> diff --git a/target-arm/translate.c b/target-arm/translate.c
> index 652cac9..e2fa4df 100644
> --- a/target-arm/translate.c
> +++ b/target-arm/translate.c
> @@ -253,8 +253,8 @@ static void gen_revsh(TCGv var)
> TCGv tmp = new_tmp();
> tcg_gen_shri_i32(tmp, var, 8);
> tcg_gen_andi_i32(tmp, tmp, 0x00ff);
> - tcg_gen_shli_i32(var, var, 8);
> tcg_gen_ext8s_i32(var, var);
> + tcg_gen_shli_i32(var, var, 8);
> tcg_gen_or_i32(var, var, tmp);
> dead_tmp(tmp);
> }
> --
> 1.7.0.4
>
>
>
--
Aurelien Jarno GPG: 1024D/F1BCDB73
address@hidden http://www.aurel32.net
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