linux-kernel - [PATCH] Revert "kbuild: use -Oz instead of -Os when using clang"

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Date:   Mon, 18 Mar 2019 17:10:05 -0400
From:   Matthias Kaehlcke <mka@...omium.org>
To:     Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Michal Marek <michal.lkml@...kovi.net>
Cc:     linux-kbuild@...r.kernel.org, linux-kernel@...r.kernel.org,
        Behan Webster <behanw@...verseincode.com>,
        Peter Zijlstra <peterz@...radead.org>,
        "H . Peter Anvin" <hpa@...or.com>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Manoj Gupta <manojgupta@...omium.org>,
        Tiancong Wang <tcwang@...omium.org>,
        Stephen Hines <srhines@...gle.com>,
        clang-built-linux@...glegroups.com,
        Matthias Kaehlcke <mka@...omium.org>
Subject: [PATCH] Revert "kbuild: use -Oz instead of -Os when using clang"

The clang option -Oz enables *aggressive* optimization for size,
which doesn't necessarily result in smaller images, but can have
negative impact on performance. Switch back to the less aggressive
-Os.

This reverts commit 6748cb3c299de1ffbe56733647b01dbcc398c419.

Suggested-by: Peter Zijlstra <peterz@...radead.org>
Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
---
 Makefile | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index 9ef547fc7ffe..191f3ce3cb5e 100644
--- a/Makefile
+++ b/Makefile
@@ -667,7 +667,7 @@ KBUILD_CFLAGS	+= $(call cc-disable-warning, format-overflow)
 KBUILD_CFLAGS	+= $(call cc-disable-warning, int-in-bool-context)

 ifdef CONFIG_CC_OPTIMIZE_FOR_SIZE
-KBUILD_CFLAGS	+= $(call cc-option,-Oz,-Os)
+KBUILD_CFLAGS	+= -Os
 else
 KBUILD_CFLAGS   += -O2
 endif
-- 
2.21.0.225.g810b269d1ac-goog