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From: "Jason A. Donenfeld" <Jason@zx2c4.com>
To: linux-kernel@vger.kernel.org
Cc: "Jason A. Donenfeld" <Jason@zx2c4.com>,
	linux-kbuild@vger.kernel.org, x86@kernel.org,
	stable@vger.kernel.org, hjl.tools@gmail.com,
	Peter Zijlstra <peterz@infradead.org>,
	Jakub Jelinek <jakub@redhat.com>,
	Oleksandr Natalenko <oleksandr@redhat.com>,
	Arnd Bergmann <arnd@arndb.de>,
	Andrew Morton <akpm@linux-foundation.org>,
	David Laight <David.Laight@aculab.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Masahiro Yamada <yamada.masahiro@socionext.com>
Subject: [PATCH v2] Kconfig: default to CC_OPTIMIZE_FOR_PERFORMANCE_O3 for gcc >= 10
Date: Mon, 11 May 2020 15:57:20 -0600	[thread overview]
Message-ID: <20200511215720.303181-1-Jason@zx2c4.com> (raw)
In-Reply-To: <20200508090202.7s3kcqpvpxx32syu@butterfly.localdomain>

GCC 10 appears to have changed -O2 in order to make compilation time
faster when using -flto, seemingly at the expense of performance, in
particular with regards to how the inliner works. Since -O3 these days
shouldn't have the same set of bugs as 10 years ago, this commit
defaults new kernel compiles to -O3 when using gcc >= 10.

Cc: linux-kbuild@vger.kernel.org
Cc: x86@kernel.org
Cc: stable@vger.kernel.org
Cc: hjl.tools@gmail.com
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jakub Jelinek <jakub@redhat.com>
Cc: Oleksandr Natalenko <oleksandr@redhat.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: David Laight <David.Laight@aculab.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
---
Changes v1->v2:
 - [Oleksandr] Remove O3 dependency on ARC.

 init/Kconfig | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index 9e22ee8fbd75..f76ec3ccc883 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1245,7 +1245,8 @@ config BOOT_CONFIG
 
 choice
 	prompt "Compiler optimization level"
-	default CC_OPTIMIZE_FOR_PERFORMANCE
+	default CC_OPTIMIZE_FOR_PERFORMANCE_O3 if GCC_VERSION >= 100000
+	default CC_OPTIMIZE_FOR_PERFORMANCE if (GCC_VERSION < 100000 || CC_IS_CLANG)
 
 config CC_OPTIMIZE_FOR_PERFORMANCE
 	bool "Optimize for performance (-O2)"
@@ -1256,7 +1257,6 @@ config CC_OPTIMIZE_FOR_PERFORMANCE
 
 config CC_OPTIMIZE_FOR_PERFORMANCE_O3
 	bool "Optimize more for performance (-O3)"
-	depends on ARC
 	imply CC_DISABLE_WARN_MAYBE_UNINITIALIZED  # avoid false positives
 	help
 	  Choosing this option will pass "-O3" to your compiler to optimize
-- 
2.26.2


  parent reply	other threads:[~2020-05-11 21:57 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-05-07 22:45 [PATCH] " Jason A. Donenfeld
2020-05-08  8:35 ` Peter Zijlstra
2020-05-08  9:02 ` Oleksandr Natalenko
2020-05-08 11:21   ` Jason A. Donenfeld
2020-05-08 11:33     ` Oleksandr Natalenko
2020-05-08 11:49       ` Arnd Bergmann
2020-05-08 12:07         ` Jason A. Donenfeld
2020-05-08 13:04           ` Arnd Bergmann
2020-05-08 15:06         ` Joe Perches
2020-05-08 15:09           ` Arnd Bergmann
2020-05-10 12:47           ` David Laight
2020-05-10 17:45             ` Joe Perches
2020-05-10 18:58               ` David Laight
2020-05-12  1:10             ` Masahiro Yamada
2020-05-11 21:57   ` Jason A. Donenfeld [this message]
2020-05-12  0:04     ` [PATCH v2] " Linus Torvalds
2020-05-12  0:09       ` Linus Torvalds
2020-05-12  0:43       ` Jason A. Donenfeld
2020-05-12  8:44       ` Richard Biener
2020-05-13 11:27 ` [PATCH] " Artem S. Tashkinov

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