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[PATCH 2/7] Makefile, x86, LLVM: disable unsupported optimization flags

From Michael Davidson <md@google.com>
Newsgroups linux.kernel
Subject [PATCH 2/7] Makefile, x86, LLVM: disable unsupported optimization flags
Date 2017-03-17 01:30 +0100
Message-ID <tlNWh-6eK-11@gated-at.bofh.it> (permalink)
References <tlNWh-6eK-9@gated-at.bofh.it>
Organization linux.* mail to news gateway

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Unfortunately, while clang generates a warning about these flags
being unsupported it still exits with a status of 0 so we have
to explicitly disable them instead of just using a cc-option check.

Signed-off-by: Michael Davidson <md@google.com>
---
 Makefile          | 2 ++
 arch/x86/Makefile | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/Makefile b/Makefile
index b21fd0ca2946..5e97e5fc1eea 100644
--- a/Makefile
+++ b/Makefile
@@ -629,7 +629,9 @@ ARCH_AFLAGS :=
 ARCH_CFLAGS :=
 include arch/$(SRCARCH)/Makefile
 
+ifneq ($(cc-name),clang)
 KBUILD_CFLAGS	+= $(call cc-option,-fno-delete-null-pointer-checks,)
+endif
 KBUILD_CFLAGS	+= $(call cc-disable-warning,frame-address,)
 
 ifdef CONFIG_LD_DEAD_CODE_DATA_ELIMINATION
diff --git a/arch/x86/Makefile b/arch/x86/Makefile
index 2d449337a360..894a8d18bf97 100644
--- a/arch/x86/Makefile
+++ b/arch/x86/Makefile
@@ -87,11 +87,13 @@ else
         KBUILD_AFLAGS += -m64
         KBUILD_CFLAGS += -m64
 
+ifneq ($(cc-name),clang)
         # Align jump targets to 1 byte, not the default 16 bytes:
         KBUILD_CFLAGS += -falign-jumps=1
 
         # Pack loops tightly as well:
         KBUILD_CFLAGS += -falign-loops=1
+endif
 
         # Don't autogenerate traditional x87 instructions
         KBUILD_CFLAGS += $(call cc-option,-mno-80387)
-- 
2.12.0.367.g23dc2f6d3c-goog

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[PATCH 2/7] Makefile, x86, LLVM: disable unsupported optimization flags Michael Davidson <md@google.com> - 2017-03-17 01:30 +0100
  Re: [PATCH 2/7] Makefile, x86, LLVM: disable unsupported optimization  flags "H. Peter Anvin" <hpa@zytor.com> - 2017-03-17 22:40 +0100
  Re: [PATCH 2/7] Makefile, x86, LLVM: disable unsupported optimization  flags "H. Peter Anvin" <hpa@zytor.com> - 2017-03-17 22:50 +0100

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