linux-kernel - [tip:x86/build] x86/kbuild: Use cc-option to enable -falign-{jumps/loops}

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Message-ID: <tip-2c4fd1ac3ff167c91272dc43c7bfd2269ef61557@git.kernel.org>
Date:   Tue, 18 Apr 2017 00:25:44 -0700
From:   tip-bot for Matthias Kaehlcke <tipbot@...or.com>
To:     linux-tip-commits@...r.kernel.org
Cc:     mka@...omium.org, torvalds@...ux-foundation.org,
        linux-kernel@...r.kernel.org, mingo@...nel.org,
        peterz@...radead.org, yamada.masahiro@...ionext.com, md@...gle.com,
        ghackmann@...gle.com, tglx@...utronix.de, hpa@...or.com
Subject: [tip:x86/build] x86/kbuild: Use cc-option to enable
 -falign-{jumps/loops}

Commit-ID:  2c4fd1ac3ff167c91272dc43c7bfd2269ef61557
Gitweb:     http://git.kernel.org/tip/2c4fd1ac3ff167c91272dc43c7bfd2269ef61557
Author:     Matthias Kaehlcke <mka@...omium.org>
AuthorDate: Thu, 13 Apr 2017 10:26:09 -0700
Committer:  Ingo Molnar <mingo@...nel.org>
CommitDate: Mon, 17 Apr 2017 12:39:37 +0200

x86/kbuild: Use cc-option to enable -falign-{jumps/loops}

clang currently does not support these optimizations, only enable them
when they are available.

Signed-off-by: Matthias Kaehlcke <mka@...omium.org>
Cc: Greg Hackmann <ghackmann@...gle.com>
Cc: Linus Torvalds <torvalds@...ux-foundation.org>
Cc: Masahiro Yamada <yamada.masahiro@...ionext.com>
Cc: Michael Davidson <md@...gle.com>
Cc: Peter Zijlstra <peterz@...radead.org>
Cc: Thomas Gleixner <tglx@...utronix.de>
Cc: grundler@...omium.org
Link: http://lkml.kernel.org/r/20170413172609.118122-1-mka@chromium.org
Signed-off-by: Ingo Molnar <mingo@...nel.org>
---
 arch/x86/Makefile | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index a94a4d1..73604e1 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -88,10 +88,10 @@ else
         KBUILD_CFLAGS += -m64
 
         # Align jump targets to 1 byte, not the default 16 bytes:
-        KBUILD_CFLAGS += -falign-jumps=1
+        KBUILD_CFLAGS += $(call cc-option,-falign-jumps=1)
 
         # Pack loops tightly as well:
-        KBUILD_CFLAGS += -falign-loops=1
+        KBUILD_CFLAGS += $(call cc-option,-falign-loops=1)
 
         # Don't autogenerate traditional x87 instructions
         KBUILD_CFLAGS += $(call cc-option,-mno-80387)