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From: Richard Henderson <rth@twiddle.net>
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Date: Fri, 6 May 2016 09:48:59 -1000
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Subject: Re: [Qemu-devel] [PATCH 34/52] target-m68k: add 64bit mull
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To: Laurent Vivier <laurent@vivier.eu>, qemu-devel@nongnu.org
Cc: schwab@linux-m68k.org, gerg@uclinux.org, agraf@suse.de

On 05/04/2016 11:08 AM, Laurent Vivier wrote:
> +    if (m68k_feature(s->env, M68K_FEATURE_M68000)) {
> +        if (sign) {
> +            tcg_gen_muls2_i32(QREG_CC_N, QREG_CC_V, src1, DREG(ext, 12));
> +        } else {
> +            tcg_gen_mulu2_i32(QREG_CC_N, QREG_CC_V, src1, DREG(ext, 12));
> +        }
> +        tcg_gen_mov_i32(DREG(ext, 12), QREG_CC_N);
> +
> +        tcg_gen_mov_i32(QREG_CC_Z, QREG_CC_N);
> +        tcg_gen_movi_i32(QREG_CC_C, 0);
> +
> +        set_cc_op(s, CC_OP_FLAGS);

Unsigned overflow requires -(QREG_CC_V != 0).
Signed overflow requires -(QREG_CC_V != (QREG_CC_N >> 31)).


r~