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References: <20190213143322.31371-1-david@redhat.com>
	<20190213143322.31371-13-david@redhat.com>
From: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <634cf76a-f1b9-138a-2ed4-e666c4be35f1@linaro.org>
Date: Wed, 13 Feb 2019 11:31:49 -0800
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Subject: Re: [Qemu-devel] [PATCH v2 12/15] s390x/tcg: Implement XxC and
 checks for most FP instructions
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To: David Hildenbrand <david@redhat.com>, qemu-devel@nongnu.org
Cc: qemu-s390x@nongnu.org, Thomas Huth <thuth@redhat.com>, Halil Pasic <pasic@linux.ibm.com>, Christian Borntraeger <borntraeger@de.ibm.com>, Janosch Frank <frankja@linux.ibm.com>, Cornelia Huck <cohuck@redhat.com>

On 2/13/19 6:33 AM, David Hildenbrand wrote:
> With the floating-point extension facility
> - CONVERT FROM LOGICAL
> - CONVERT TO LOGICAL
> - CONVERT TO FIXED
> - CONVERT FROM FIXED
> - LOAD FP INTEGER
> have both, a rounding mode specification and the inexact-exception control
> (XxC). Other instructions will be handled separatly.
> 
> Check for valid rounding modes and forward also the XxC (via m4). To avoid
> a lot of boilerplate code and changes to the helpers, combine both, the
> m3 and m4 field in a combined 32 bit TCG variable. Perform checks at
> a central place, taking in account if the m3 or m4 field was ignore
> before the floating-point extension facility was introduced.
> 
> Signed-off-by: David Hildenbrand <david@redhat.com>

Reviewed-by: Richard Henderson <richard.henderson@linaro.org>

> +static inline bool xxc_from_m34(uint32_t m34)
> +{
> +    /* XxC is bit 1 of m4 */
> +    return (extract32(m34, 4, 4) & 0x4) != 0;

Better as extract32(m32, 6, 1);


r~