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@xxxxxxxxx> Link: https://www.mail-archive.com/linux-crypto@xxxxxxxxxxxxxxx/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@xxxxxxxx> --- v2: fix a typo in the Makefile --- crypto/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) 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 -- 2.9.0
