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Date: Fri, 21 May 2021 21:16:35 -0400
From: Mike Frysinger <vapier@gentoo.org>
To: Faraz Shahbazker <fshahbazker@wavecomp.com>
Cc: gdb-patches@sourceware.org, "Maciej W . Rozycki" <macro@orcam.me.uk>,
 Chao-ying Fu <cfu@wavecomp.com>
Subject: Re: [PATCH 1/5] sim: Allow toggling of quiet NaN-bit semantics
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Mail-Followup-To: Faraz Shahbazker <fshahbazker@wavecomp.com>,
 gdb-patches@sourceware.org,
 "Maciej W . Rozycki" <macro@orcam.me.uk>,
 Chao-ying Fu <cfu@wavecomp.com>
References: <20210520074554.1465327-1-fshahbazker@wavecomp.com>
 <20210520074554.1465327-2-fshahbazker@wavecomp.com>
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On 20 May 2021 13:15, Faraz Shahbazker wrote:
> IEEE754-1985 specifies the top bit of the mantissa as an indicator
> of signalling vs. quiet NaN, but does not define the precise semantics.
> Most architectures treat this bit as indicating quiet NaN, but legacy
> (pre-R6) MIPS goes the other way and treats it as signalling NaN.
> 
> This used to be controlled by a macro that was only defined for MIPS.
> This patch replaces the macro with a variable to track the current
> semantics of the NaN bit and allows differentiation between older
> (pre-R6) and and newer MIPS cores.

looks good ... minor style nits

> --- a/sim/common/sim-fpu.c
> +++ b/sim/common/sim-fpu.c
> 
> +/* IEEE 754-1985 specifies the top bit of the mantissa as an indicator
> +   of signalling vs. quiet NaN, but does not specify the semantics.
> +   Most architectures treat this bit as quiet NaN, but legacy (pre-R6)
> +   MIPS goes the other way and treats it as signalling.  This variable
> +   tracks the current semantics of the NaN bit and allows differentiation
> +   between pre-R6 and R6 MIPS cores.  */
> +int sim_fpu_quiet_nan_inverted = 0;

we're C11 now, so we can assume stdbool.h.  so switch to bool/true/false.

> --- a/sim/common/sim-fpu.h
> +++ b/sim/common/sim-fpu.h
>  
> +/* Toggle quiet NaN semantics.  */
>  
> +extern int sim_fpu_quiet_nan_inverted;

omit the blank line between the two lines
-mike