On 27.02.2026 11:58, Edwin Török wrote:
> clang-21's built-in assembler is enabled by default, but it doesn't
> support some mnemonics:
> ```
> test_x86_emulator.c:2636:36: error: invalid instruction mnemonic 'fsaves'
> 2636 | "fidivs %1\n\t"
> test_x86_emulator.c:2640:24: error: invalid instruction mnemonic 'frstors'
> 2640 | asm volatile ( "frstors %0" :: "m" (res[25]) : "memory" );
> | ^
> test_x86_emulator.c:4251:24: error: invalid instruction mnemonic 'vpcmpestriq'
> 4251 | put_insn(vpcmpestri,
> | ^
> ```
Btw, for this last one to work with gcc older than 7.x what I have in a
local "helper" patch is
# if __GNUC__ < 7//temp
put_insn(vpcmpestri,
".byte 0xC4, 0xE3, 0xF9, 0x61, 0x16, 0x7A")
# else
put_insn(vpcmpestri,
"vpcmpestriq $0b01111010, (%1), %%xmm2")
# endif
> Use the external assembler with Clang for consistency with GCC.
>
> Signed-off-by: Edwin Török <[email protected]>
Acked-by: Jan Beulich <[email protected]>
> --- a/tools/tests/x86_emulator/Makefile
> +++ b/tools/tests/x86_emulator/Makefile
> @@ -297,6 +297,11 @@ x86_emulate:
>
> HOSTCFLAGS-x86_64 := -fno-PIE
> $(call cc-option-add,HOSTCFLAGS-x86_64,HOSTCC,-no-pie)
> +
> +# clang's integrated as does not support some mnemonics:
> +# https://github.com/llvm/llvm-project/issues/183635
I see they already confirmed at least the {,v}pcmpestri issue.
Jan
