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| author |   Jason A. Donenfeld <Jason@zx2c4.com> | 2017-11-03 15:18:58 +0100 |
|---|---|---|
| committer |   Will Deacon <will.deacon@arm.com> | 2017-11-03 15:24:21 +0000 |
| commit | fb8722735f50cd51204bfbeefa2e5e7e9ff5b2be (patch) | |
| tree | 95fb1a4d8296174d047afc3dd33abf2c053b6622 /arch/arm64/Makefile | |
| parent | arm64/sve: Add documentation (diff) | |
| download | linux-dev-fb8722735f50cd51204bfbeefa2e5e7e9ff5b2be.tar.xz linux-dev-fb8722735f50cd51204bfbeefa2e5e7e9ff5b2be.zip | |
arm64: support __int128 on gcc 5+
Versions of gcc prior to gcc 5 emitted a __multi3 function call when
dealing with TI types, resulting in failures when trying to link to
libgcc, and more generally, bad performance. However, since gcc 5,
the compiler supports actually emitting fast instructions, which means
we can at long last enable this option and receive the speedups.
The gcc commit that added proper Aarch64 support is:
https://gcc.gnu.org/git/?p=gcc.git;a=commitdiff;h=d1ae7bb994f49316f6f63e6173f2931e837a351d
This commit appears to be part of the gcc 5 release.
There are still a few instructions, __ashlti3 and __ashrti3, which
require libgcc, which is fine. Rather than linking to libgcc, we
simply provide them ourselves, since they're not that complicated.
Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Will Deacon <will.deacon@arm.com>
Diffstat (limited to 'arch/arm64/Makefile')
| -rw-r--r-- | arch/arm64/Makefile | 2 |
1 files changed, 2 insertions, 0 deletions
diff --git a/arch/arm64/Makefile b/arch/arm64/Makefile index 953e43dd0417..b35788c909f1 100644 --- a/arch/arm64/Makefile +++ b/arch/arm64/Makefile @@ -57,6 +57,8 @@ KBUILD_AFLAGS += $(lseinstr) $(brokengasinst) KBUILD_CFLAGS += $(call cc-option,-mabi=lp64) KBUILD_AFLAGS += $(call cc-option,-mabi=lp64) +KBUILD_CFLAGS += $(call cc-ifversion, -ge, 0500, -DCONFIG_ARCH_SUPPORTS_INT128) + ifeq ($(CONFIG_CPU_BIG_ENDIAN), y) KBUILD_CPPFLAGS += -mbig-endian CHECKFLAGS += -D__AARCH64EB__ |