[Buildroot] [PATCH 1/3] arch/mips: inverse the NaN logic

From: Yann E. MORIN <yann.morin.1998@free.fr>
To: buildroot@busybox.net
Subject: [Buildroot] [PATCH 1/3] arch/mips: inverse the NaN logic
Date: Sat, 7 Oct 2017 14:22:33 +0200	[thread overview]
Message-ID: <20171007122233.GH21901@scaer> (raw)
In-Reply-To: <93faf8c9-2223-3305-308c-6da56200a61d@gmail.com>

Romain, All,

On 2017-10-07 12:18 +0200, Romain Naour spake thusly:
> Le 03/09/2017 ? 11:53, Yann E. MORIN a ?crit?:
> > Currentlym the possibility to choose the NaN encoding is conditional to
> > having a sufficiently recent gcc version.
> > 
> > Which means that the architecture selection depends on the gcc version.
> > 
> > But that's opposite to what we've always done in Buildroot: the software
> > versions are conditional to the architecture options. There is nothing
> > we can do about the hardware: it is there, we can't change it, while we
> > can restrict ourselves to using software that is working on said
> > hardware.
> > 
> > Thus, we inverse the logic, to move the condition onto the software
> > side: whenever NaN-2008 are selected, we restrict the toolchain
> > selection to at least a gcc-4.9.
> > 
> > But now, the option with the NaN type is always set, so we must enclose
> > the code in gcc.mk inside a HAS_NAN_OPTION condition, as is already done
> > for the external toolchain case.
> > 
> > Signed-off-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
> > Cc: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
> > Cc: Vicente Olivert Riera <Vincent.Riera@imgtec.com>
> > ---
> >  arch/Config.in.mips | 2 +-
> >  package/gcc/gcc.mk  | 2 ++
> >  2 files changed, 3 insertions(+), 1 deletion(-)
> > 
> > diff --git a/arch/Config.in.mips b/arch/Config.in.mips
> > index c08b2a2968..13d1a477e6 100644
> > --- a/arch/Config.in.mips
> > +++ b/arch/Config.in.mips
> > @@ -176,10 +176,10 @@ config BR2_MIPS_NAN_LEGACY
> >  
> >  config BR2_MIPS_NAN_2008
> >  	bool
> > +	select BR2_ARCH_NEEDS_GCC_AT_LEAST_4_9
> 
> This series require the previous series "arch: some require a minimal gcc
> version" adding this option.

Yes, that's why the four series were replies one to the previous, so that
they are correctly threaded in your MUA. As long as you use a decent MUA,
that is. ;-]

Regards,
Yann E. MORIN.

> Best regards,
> Romain
> 
> >  
> >  choice
> >  	prompt "Target NaN"
> > -	depends on BR2_TOOLCHAIN_HAS_MNAN_OPTION
> >  	depends on BR2_mips_32r5 || BR2_mips_64r5
> >  	default BR2_MIPS_ENABLE_NAN_2008
> >  	help
> > diff --git a/package/gcc/gcc.mk b/package/gcc/gcc.mk
> > index 49ccccf56f..d45b6d7a06 100644
> > --- a/package/gcc/gcc.mk
> > +++ b/package/gcc/gcc.mk
> > @@ -207,9 +207,11 @@ endif
> >  ifneq ($(call qstrip,$(BR2_GCC_TARGET_ABI)),)
> >  HOST_GCC_COMMON_CONF_OPTS += --with-abi=$(BR2_GCC_TARGET_ABI)
> >  endif
> > +ifeq ($(BR2_TOOLCHAIN_HAS_MNAN_OPTION),y)
> >  ifneq ($(call qstrip,$(BR2_GCC_TARGET_NAN)),)
> >  HOST_GCC_COMMON_CONF_OPTS += --with-nan=$(BR2_GCC_TARGET_NAN)
> >  endif
> > +endif
> >  ifneq ($(call qstrip,$(BR2_GCC_TARGET_FP32_MODE)),)
> >  HOST_GCC_COMMON_CONF_OPTS += --with-fp-32=$(BR2_GCC_TARGET_FP32_MODE)
> >  endif
> > 
> 

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