On Tue, 10 Nov 2020 at 02:55, Nick Desaulniers <[email protected]> wrote: > > On Sat, Nov 7, 2020 at 12:29 AM Ard Biesheuvel <[email protected]> wrote: > > > > On Sat, 7 Nov 2020 at 01:11, Jian Cai <[email protected]> wrote: > > > > > > This patch replaces 6 IWMMXT instructions Clang's integrated assembler > > > does not support in iwmmxt.S using macros, while making sure GNU > > > assembler still emit the same instructions. This should be easier than > > > providing full IWMMXT support in Clang. > > > > > > "Intel Wireless MMX Technology - Developer Guide - August, 2002" should > > > be referenced for the encoding schemes of these extensions. > > > > > > Link: https://github.com/ClangBuiltLinux/linux/issues/975 > > > > > > Suggested-by: Nick Desaulniers <[email protected]> > > > Suggested-by: Ard Biesheuvel <[email protected]> > > > Signed-off-by: Jian Cai <[email protected]> > > > > Please make sure you test this carefully on BE32, as the instruction > > byte order used by .inst is LE IIRC > > Unless that was a recent-ish change in GAS, it looks like I get the > same disassembly/encodings before/after this patch for > CONFIG_BIG_ENDIAN with GNU as. > > $ ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- make CC=clang -j71 defconfig > $ ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- make CC=clang -j71 menuconfig > <enable CPU_BIG_ENDIAN> > $ grep BIG_ENDIAN .config > CONFIG_CPU_BIG_ENDIAN=y > CONFIG_ARCH_SUPPORTS_BIG_ENDIAN=y > $ ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- make CC=clang -j71 > arch/arm/kernel/iwmmxt.o > $ arm-linux-gnueabi-objdump -dr arch/arm/kernel/iwmmxt.o > gas_before.txt > $ b4 am > https://lore.kernel.org/lkml/[email protected]/ > -o - | git am > $ ARCH=arm CROSS_COMPILE=arm-linux-gnueabi- make CC=clang -j71 > arch/arm/kernel/iwmmxt.o > $ arm-linux-gnueabi-objdump -dr arch/arm/kernel/iwmmxt.o > gas_after.txt > $ diff -u gas_before.txt gas_after.txt > $ echo $? > 0 > > (Orthogonal, it looks like llvm-objdump has issues decoding > elf32-bigarm that we'll need to fix.) > > Either way the patch LGTM for IWMMXT, thanks Jian for the patch and > Ard for the suggestions. > > Reviewed-by: Nick Desaulniers <[email protected]> > Tested-by: Nick Desaulniers <[email protected]>
BE32 != BE8 Please use, e.g., ixp4xx_defconfig with IWMMXT and BE enabled. It seems like .inst does the right thing here, i.e., the assembler knows that it should emit BE for BE32 and LE for BE8, but it needs to be confirmed.
