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authorArnd Bergmann <arnd@arndb.de>2018-01-15 17:07:22 +0100
committerHerbert Xu <herbert@gondor.apana.org.au>2018-01-20 11:43:36 +1100
commit6e36719fbe90213fbba9f50093fa2d4d69b0e93c (patch)
treec010d9fb49825180e494de43917430f304df5418 /crypto
parent5abc8db013174ef6022bf7af81adf210c54e4549 (diff)
crypto: aes-generic - fix aes-generic regression on powerpc
My last bugfix added -Os on the command line, which unfortunately caused a build regression on powerpc in some configurations. I've done some more analysis of the original problem and found slightly different workaround that avoids this regression and also results in better performance on gcc-7.0: -fcode-hoisting is an optimization step that got added in gcc-7 and that for all gcc-7 versions causes worse performance. This disables -fcode-hoisting on all compilers that understand the option. For gcc-7.1 and 7.2 I found the same performance as my previous patch (using -Os), in gcc-7.0 it was even better. On gcc-8 I could see no change in performance from this patch. In theory, code hoisting should not be able make things better for the AES cipher, so leaving it disabled for gcc-8 only serves to simplify the Makefile change. Reported-by: kbuild test robot <fengguang.wu@intel.com> Link: https://www.mail-archive.com/linux-crypto@vger.kernel.org/msg30418.html Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83356 Link: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83651 Fixes: 148b974deea9 ("crypto: aes-generic - build with -Os on gcc-7+") Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Diffstat (limited to 'crypto')
-rw-r--r--crypto/Makefile2
1 files changed, 1 insertions, 1 deletions
diff --git a/crypto/Makefile b/crypto/Makefile
index daa69360e054..cdbc03b35510 100644
--- a/crypto/Makefile
+++ b/crypto/Makefile
@@ -99,7 +99,7 @@ obj-$(CONFIG_CRYPTO_TWOFISH_COMMON) += twofish_common.o
obj-$(CONFIG_CRYPTO_SERPENT) += serpent_generic.o
CFLAGS_serpent_generic.o := $(call cc-option,-fsched-pressure) # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79149
obj-$(CONFIG_CRYPTO_AES) += aes_generic.o
-CFLAGS_aes_generic.o := $(call cc-ifversion, -ge, 0701, -Os) # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83356
+CFLAGS_aes_generic.o := $(call cc-option,-fno-code-hoisting) # https://gcc.gnu.org/bugzilla/show_bug.cgi?id=83356
obj-$(CONFIG_CRYPTO_AES_TI) += aes_ti.o
obj-$(CONFIG_CRYPTO_CAMELLIA) += camellia_generic.o
obj-$(CONFIG_CRYPTO_CAST_COMMON) += cast_common.o