From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-lf1-f53.google.com (mail-lf1-f53.google.com [209.85.167.53]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 395E129CA for ; Mon, 24 Jan 2022 22:49:44 +0000 (UTC) Received: by mail-lf1-f53.google.com with SMTP id b14so53116861lff.3 for ; Mon, 24 Jan 2022 14:49:44 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=L4FKVaUGrauEO19bQNy974TXmzxVW9J7iYHTfxlUUe0=; b=Ltf96k/D+fF5Pb2mwKK5EKdbvYpuHA9dhhZngLNsHVyqwx3/ZC3rSa1wmbL/OgvTmY jCCwm5pscq/cY+kvjhdSb+LlmzCvymvDrMLY2+sqyd37kssgaUQw447XmlXWyIYTHk/L 3Wdbt2i5bjkeVNtZ6X8i3PEAqirvbrOker/pZBsaeDqzWD17KRtnOwNkatWQDNjiLa41 qWcoBn3z8ahMLD2/yrk/AvrSYH7VTiouD9zozEZsHJgAUqQTYx7mNZK24a+t9rsragcQ lROAyYD8W4LF3SpZ+DgSV00PUMTIBkzWcblKEh7QdxBuNvoXAjBf/J7z68z49B5j4/0g toXg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=L4FKVaUGrauEO19bQNy974TXmzxVW9J7iYHTfxlUUe0=; b=zx6dkzFvJm2uNegzByPcuCnjvkFqox8t3os8KCgdNcJI+ILcvH1HvpNtFWR1CelX51 5iFy2X5bSY+IXje4foKbbEb23QQ1NytfWenM3usqjJ5ageOXmWxeYRki1hnATOPBrWfP 35B8UuIG9oFAzZVfDjPF98nv8SlTaRwA68+k7+kzD6liJSnd7vcsSz4/hvIkpJhQVsgd GZs330kxY2j+MoXgprXTwGK+1ODMAzaCXWL4EwJ3Ll+3WgEktenByi0plEITsySrDqrm zNOzcoAWZ1SpckSgbyY6yzVSzSYFgYalMFBXsa55q762fmnNM659oitPV1OK5qssInmU Z2VA== X-Gm-Message-State: AOAM533e62RsWkec+Bz8w0perQbkqA20QU2vECccbyAMN9/NRtVGQp6r 7kkEs07zou+OvZvyRVkHmwlP/ZGecBN/bZX0Y/YFiQ== X-Google-Smtp-Source: ABdhPJzfAi0qCoM2ShuPeiANPpPDrqkZkG/Ae5xDdnF8I0qIxBXdDONOKVcQiGcNFCiWRx0rY3TrIrt5rQPZp9v4qAY= X-Received: by 2002:a05:6512:b0d:: with SMTP id w13mr14721099lfu.240.1643064581970; Mon, 24 Jan 2022 14:49:41 -0800 (PST) Precedence: bulk X-Mailing-List: llvm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 References: <20220120214001.1879469-1-nathan@kernel.org> <20220120214001.1879469-2-nathan@kernel.org> In-Reply-To: From: Nick Desaulniers Date: Mon, 24 Jan 2022 14:49:29 -0800 Message-ID: Subject: Re: [PATCH 2/2] MIPS: Loongson64: Wrap -mno-branch-likely with cc-option To: Nathan Chancellor Cc: Masahiro Yamada , Huacai Chen , Jiaxun Yang , Thomas Bogendoerfer , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org, llvm@lists.linux.dev Content-Type: text/plain; charset="UTF-8" On Mon, Jan 24, 2022 at 2:37 PM Nathan Chancellor wrote: > > On Mon, Jan 24, 2022 at 12:40:58PM -0800, Nick Desaulniers wrote: > > On Thu, Jan 20, 2022 at 1:40 PM Nathan Chancellor wrote: > > > > > > This flag is not supported by clang, which results in a warning: > > > > > > clang-14: warning: argument unused during compilation: '-mno-branch-likely' [-Wunused-command-line-argument] > > > > > > This breaks cc-option, which adds -Werror to make this warning fatal and > > > catch flags that are not supported. Wrap the flag in cc-option so that > > > it does not cause cc-option to fail, which can cause randconfigs to be > > > really noisy. > > > > > > Signed-off-by: Nathan Chancellor > > > > We should convert more of these tests to Kconfig checks that run once > > per configuration, rather than multiple times for a build. IIRC Linus > > mentioned this somewhere...yeah, the -Wimplicit-fallthrough patches. > > See > > dee2b702bcf06 ("kconfig: Add support for -Wimplicit-fallthrough") > > > > I wonder if we can check ARCH or SUBARCH in Kconfig to limit invoking > > the tool under test for certain arch specific command line flags? > > > > I'll take this patch over such a larger change, but I think towards > > the goal of speeding up already configured builds, we eventually want > > to be migrating cc-option and ld-option checks to Kconfig. > > > > Reviewed-by: Nick Desaulniers > > Something like this appears to work, if that is more preferrable? > > diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig > index 058446f01487..a27a3ade810e 100644 > --- a/arch/mips/Kconfig > +++ b/arch/mips/Kconfig > @@ -3232,3 +3232,9 @@ endmenu > source "arch/mips/kvm/Kconfig" > > source "arch/mips/vdso/Kconfig" > + > +config CC_MNO_BRANCH_LIKELY > + string > + default "-mno-branch-likely" > + depends on MACH_LOONGSON64 || MACH_LOONGSON2EF > + depends on $(cc-option,-mno-branch-likely) > diff --git a/arch/mips/loongson2ef/Platform b/arch/mips/loongson2ef/Platform > index 50e659aca543..66ed09581417 100644 > --- a/arch/mips/loongson2ef/Platform > +++ b/arch/mips/loongson2ef/Platform > @@ -41,6 +41,6 @@ cflags-y += $(call cc-option,-mno-loongson-mmi) > # Loongson Machines' Support > # > > -cflags-$(CONFIG_MACH_LOONGSON2EF) += -I$(srctree)/arch/mips/include/asm/mach-loongson2ef -mno-branch-likely > +cflags-$(CONFIG_MACH_LOONGSON2EF) += -I$(srctree)/arch/mips/include/asm/mach-loongson2ef $(CONFIG_CC_MNO_BRANCH_LIKELY) Does that allow someone to modify the value for CC_MNO_BRANCH_LIKELY in menuconfig? If so, I'd rather the Makefiles have: cflags-$(CONFIG_CC_MNO_BRANCH_LIKELY) += -mno-branch-likely and CONFIG_CC_MNO_BRANCH_LIKELY be a bool rather than an editable string. I think that makes the Makefile more readable; you don't have to see what CONFIG_CC_MNO_BRANCH_LIKELY expands to in a different file. See also CC_HAS_ASM_GOTO and CC_HAS_ASM_GOTO_OUTPUT in init/Kconfig. > load-$(CONFIG_LEMOTE_FULOONG2E) += 0xffffffff80100000 > load-$(CONFIG_LEMOTE_MACH2F) += 0xffffffff80200000 > diff --git a/arch/mips/loongson64/Platform b/arch/mips/loongson64/Platform > index 3e660d6d3c2b..88fbdfe9ffcc 100644 > --- a/arch/mips/loongson64/Platform > +++ b/arch/mips/loongson64/Platform > @@ -33,5 +33,5 @@ cflags-y += $(call cc-option,-mno-loongson-mmi) > # Loongson Machines' Support > # > > -cflags-$(CONFIG_MACH_LOONGSON64) += -I$(srctree)/arch/mips/include/asm/mach-loongson64 -mno-branch-likely > +cflags-$(CONFIG_MACH_LOONGSON64) += -I$(srctree)/arch/mips/include/asm/mach-loongson64 $(CONFIG_CC_MNO_BRANCH_LIKELY) > load-$(CONFIG_CPU_LOONGSON64) += 0xffffffff80200000 > > > > --- > > > arch/mips/loongson64/Platform | 3 ++- > > > 1 file changed, 2 insertions(+), 1 deletion(-) > > > > > > diff --git a/arch/mips/loongson64/Platform b/arch/mips/loongson64/Platform > > > index 981d3abc150e..acf9edc9b15d 100644 > > > --- a/arch/mips/loongson64/Platform > > > +++ b/arch/mips/loongson64/Platform > > > @@ -26,5 +26,6 @@ cflags-y += $(call cc-option,-mno-loongson-mmi) > > > # Loongson Machines' Support > > > # > > > > > > -cflags-$(CONFIG_MACH_LOONGSON64) += -I$(srctree)/arch/mips/include/asm/mach-loongson64 -mno-branch-likely > > > +cflags-$(CONFIG_MACH_LOONGSON64) += -I$(srctree)/arch/mips/include/asm/mach-loongson64 > > > +cflags-$(CONFIG_MACH_LOONGSON64) += $(call cc-option,-mno-branch-likely) > > > load-$(CONFIG_CPU_LOONGSON64) += 0xffffffff80200000 > > > -- > > > 2.34.1 > > > > > > > > > > > > -- > > Thanks, > > ~Nick Desaulniers > -- Thanks, ~Nick Desaulniers