From: Ard Biesheuvel <ardb@kernel.org> To: Adrian Ratiu <adrian.ratiu@collabora.com> Cc: Linux ARM <linux-arm-kernel@lists.infradead.org>, Nathan Chancellor <natechancellor@gmail.com>, Nick Desaulniers <ndesaulniers@google.com>, Arnd Bergmann <arnd@arndb.de>, Russell King <linux@armlinux.org.uk>, Arvind Sankar <nivedita@alum.mit.edu>, kernel@collabora.com, clang-built-linux <clang-built-linux@googlegroups.com>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org> Subject: Re: [PATCH v2 1/2] arm: lib: xor-neon: remove unnecessary GCC < 4.6 warning Date: Fri, 13 Nov 2020 08:49:12 +0100 [thread overview] Message-ID: <CAMj1kXFbLRTvGuRt5J3-oEuJrrHFV9+SBGFFDNsAftGUbwoTPw@mail.gmail.com> (raw) In-Reply-To: <20201112212457.2042105-2-adrian.ratiu@collabora.com> On Thu, 12 Nov 2020 at 22:23, Adrian Ratiu <adrian.ratiu@collabora.com> wrote: > > From: Nathan Chancellor <natechancellor@gmail.com> > > Drop warning because kernel now requires GCC >= v4.9 after > commit 6ec4476ac825 ("Raise gcc version requirement to 4.9"). > > Reported-by: Nick Desaulniers <ndesaulniers@google.com> > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com> Again, this does not do what it says on the tin. If you want to disable the pragma for Clang, call that out in the commit log, and don't hide it under a GCC version change. Without the pragma, the generated code is the same as the generic code, so it makes no sense to build xor-neon.ko at all, right? > --- > arch/arm/lib/xor-neon.c | 9 +-------- > 1 file changed, 1 insertion(+), 8 deletions(-) > > diff --git a/arch/arm/lib/xor-neon.c b/arch/arm/lib/xor-neon.c > index b99dd8e1c93f..e1e76186ec23 100644 > --- a/arch/arm/lib/xor-neon.c > +++ b/arch/arm/lib/xor-neon.c > @@ -19,15 +19,8 @@ MODULE_LICENSE("GPL"); > * -ftree-vectorize) to attempt to exploit implicit parallelism and emit > * NEON instructions. > */ > -#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6) > +#ifdef CONFIG_CC_IS_GCC > #pragma GCC optimize "tree-vectorize" > -#else > -/* > - * While older versions of GCC do not generate incorrect code, they fail to > - * recognize the parallel nature of these functions, and emit plain ARM code, > - * which is known to be slower than the optimized ARM code in asm-arm/xor.h. > - */ > -#warning This code requires at least version 4.6 of GCC > #endif > > #pragma GCC diagnostic ignored "-Wunused-variable" > -- > 2.29.2 >
WARNING: multiple messages have this Message-ID (diff)
From: Ard Biesheuvel <ardb@kernel.org> To: Adrian Ratiu <adrian.ratiu@collabora.com> Cc: Arnd Bergmann <arnd@arndb.de>, Nick Desaulniers <ndesaulniers@google.com>, Russell King <linux@armlinux.org.uk>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, clang-built-linux <clang-built-linux@googlegroups.com>, Arvind Sankar <nivedita@alum.mit.edu>, Nathan Chancellor <natechancellor@gmail.com>, kernel@collabora.com, Linux ARM <linux-arm-kernel@lists.infradead.org> Subject: Re: [PATCH v2 1/2] arm: lib: xor-neon: remove unnecessary GCC < 4.6 warning Date: Fri, 13 Nov 2020 08:49:12 +0100 [thread overview] Message-ID: <CAMj1kXFbLRTvGuRt5J3-oEuJrrHFV9+SBGFFDNsAftGUbwoTPw@mail.gmail.com> (raw) In-Reply-To: <20201112212457.2042105-2-adrian.ratiu@collabora.com> On Thu, 12 Nov 2020 at 22:23, Adrian Ratiu <adrian.ratiu@collabora.com> wrote: > > From: Nathan Chancellor <natechancellor@gmail.com> > > Drop warning because kernel now requires GCC >= v4.9 after > commit 6ec4476ac825 ("Raise gcc version requirement to 4.9"). > > Reported-by: Nick Desaulniers <ndesaulniers@google.com> > Signed-off-by: Nathan Chancellor <natechancellor@gmail.com> > Signed-off-by: Adrian Ratiu <adrian.ratiu@collabora.com> Again, this does not do what it says on the tin. If you want to disable the pragma for Clang, call that out in the commit log, and don't hide it under a GCC version change. Without the pragma, the generated code is the same as the generic code, so it makes no sense to build xor-neon.ko at all, right? > --- > arch/arm/lib/xor-neon.c | 9 +-------- > 1 file changed, 1 insertion(+), 8 deletions(-) > > diff --git a/arch/arm/lib/xor-neon.c b/arch/arm/lib/xor-neon.c > index b99dd8e1c93f..e1e76186ec23 100644 > --- a/arch/arm/lib/xor-neon.c > +++ b/arch/arm/lib/xor-neon.c > @@ -19,15 +19,8 @@ MODULE_LICENSE("GPL"); > * -ftree-vectorize) to attempt to exploit implicit parallelism and emit > * NEON instructions. > */ > -#if __GNUC__ > 4 || (__GNUC__ == 4 && __GNUC_MINOR__ >= 6) > +#ifdef CONFIG_CC_IS_GCC > #pragma GCC optimize "tree-vectorize" > -#else > -/* > - * While older versions of GCC do not generate incorrect code, they fail to > - * recognize the parallel nature of these functions, and emit plain ARM code, > - * which is known to be slower than the optimized ARM code in asm-arm/xor.h. > - */ > -#warning This code requires at least version 4.6 of GCC > #endif > > #pragma GCC diagnostic ignored "-Wunused-variable" > -- > 2.29.2 > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel
next prev parent reply other threads:[~2020-11-13 7:49 UTC|newest] Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top 2020-11-12 21:24 [PATCH v2 0/2] xor-neon: Remove GCC warn & pragmas Adrian Ratiu 2020-11-12 21:24 ` Adrian Ratiu 2020-11-12 21:24 ` [PATCH v2 1/2] arm: lib: xor-neon: remove unnecessary GCC < 4.6 warning Adrian Ratiu 2020-11-12 21:24 ` Adrian Ratiu 2020-11-12 21:38 ` Nick Desaulniers 2020-11-12 21:38 ` Nick Desaulniers 2020-11-13 7:49 ` Ard Biesheuvel [this message] 2020-11-13 7:49 ` Ard Biesheuvel 2020-11-13 11:07 ` Adrian Ratiu 2020-11-13 11:07 ` Adrian Ratiu 2020-11-13 11:41 ` Ard Biesheuvel 2020-11-13 11:41 ` Ard Biesheuvel 2020-11-13 11:59 ` Adrian Ratiu 2020-11-13 11:59 ` Adrian Ratiu 2020-11-12 21:24 ` [PATCH v2 2/2] arm: lib: xor-neon: move pragma options to makefile Adrian Ratiu 2020-11-12 21:24 ` Adrian Ratiu 2020-11-12 21:40 ` Nick Desaulniers 2020-11-12 21:40 ` Nick Desaulniers 2020-11-12 21:50 ` Nathan Chancellor 2020-11-12 21:50 ` Nathan Chancellor 2020-11-13 7:50 ` Ard Biesheuvel 2020-11-13 7:50 ` Ard Biesheuvel 2020-11-13 11:17 ` Adrian Ratiu 2020-11-13 11:17 ` Adrian Ratiu
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