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Sender: Richard Henderson <rth7680@gmail.com>
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Date: Wed, 04 Dec 2013 13:10:56 +1300
From: Richard Henderson <rth@twiddle.net>
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Subject: Re: [Qemu-devel] [PATCH 12/12] target-arm: A64: add support for
 compare and branch imm
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To: Peter Maydell <peter.maydell@linaro.org>, qemu-devel@nongnu.org
Cc: patches@linaro.org, Michael Matz <matz@suse.de>, Alexander Graf <agraf@suse.de>, C Fontana <claudio.fontana@linaro.org>, Dirk Mueller <dmueller@suse.de>, Laurent Desnogues <laurent.desnogues@gmail.com>, kvmarm@lists.cs.columbia.edu

On 12/04/2013 10:51 AM, Peter Maydell wrote:
> @@ -184,6 +184,18 @@ static TCGv_i64 cpu_reg(DisasContext *s, int reg)
>      }
>  }
>  
> +/* read a cpu register in 32bit/64bit mode to dst */
> +static void read_cpu_reg(DisasContext *s, TCGv_i64 dst, int reg, int sf)
> +{
> +    if (reg == 31) {
> +        tcg_gen_movi_i64(dst, 0);
> +    } else if (sf) {
> +        tcg_gen_mov_i64(dst, cpu_X[reg]);
> +    } else { /* (!sf) */
> +        tcg_gen_ext32u_i64(dst, cpu_X[reg]);
> +    }
> +}

I think this should be more like cpu_reg and return a TCGv instead of force a
copy into a newly generated temporary.  You've got a pool of auto-freeing
temporaries, after all.

> +    if (op) { /* CBNZ */
> +        tcg_gen_brcondi_i64(TCG_COND_EQ, tcg_cmp, 0, label_nomatch);
> +    } else { /* CBZ */
> +        tcg_gen_brcondi_i64(TCG_COND_NE, tcg_cmp, 0, label_nomatch);
> +    }

Similar comments to TBNZ/TBZ apply here.


r~