Hello,
On 28.10.2022 22.00, Dmytro Kovalov via Gnupg-users wrote:
Hello,
I found a strange libgcrypt behavior on ARM with clang built.
There is a big gap in performance of libgcrypt, built by clang, in comparison
with gcc on my ARM target machine.
The simple profile test shows 100-500% advantage of gcc gcrypt.
I found an awkward workaround to beat this issue, but need your help to find
the best way to fix it.
The root cause is next:
Due to clang strict assembler syntax rules the unified assembler ARM check
doesn't pass.
Assembler check fails while ./configure for flags:
HAVE_COMPATIBLE_GCC_ARM_PLATFORM_AS
HAVE_GCC_INLINE_ASM_NEON
As a workaround I remove '%' from registers names in
configure.ac <http://configure.ac/>,
arm mips lib *.S files,
cipher/*arm.S,*armv7-neon.S files.
Could you please help with a more correct - polite way to compile libgcrypt
with assembler code?
This looks correct fix for improving compatibility with clang. It seems that
GNU assembler works with those extra '%', but clang arm assembler does not.
Only some of the arm assembly in libgcrypt have those extra '%' on register
names but not all.
-Jussi
Tested on:
libgcrypt-1.8.6
libgcrypt-1.9.3
Equipment:
build machine:
intel based cpu x86_64
Ubnuntu-20.04
Software
compiler : clang 11.1.0
linker lld : lld 11.1.0
assembler : llvm-as 11.1.0
cflags : "-m32 -march=armv7-a -mthumb -mfpu=vfpv3-d16
--target=arm-linux-gnueabihf"
arm-linux-gnueabihf sysroot based on glibc 2.31
libgcrypt configuring:
CC="arm-linux-gnueabihf-clang" \
./configure \
--with-libgpg-error-prefix=<libgpg.so path> \
--prefix=<output path> \
--host=arm-linux-gnueabihf \
--enable-static \
--disable-doc
target machine:
hardware:
model name : ARMv7 Processor rev 4 (v7l)
BogoMIPS : 2304.00
Features : half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32
lpae aes pmull sha1 sha2 crc32
Best Regards,
Dmytro Kovalov
dmytro.a.kova...@globallogic.com <mailto:dmytro.a.kova...@globallogic.com>
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