[PATCH] x86emul: correct {evex} assembler capability check

[PATCH] x86emul: correct {evex} assembler capability check

[Jan Beulich]

The {evex} pseudo prefix gets rejected by gas for insns not allowing
EVEX encoding. Except there's a gas bug due to which its check gets
bypassed for insns without operands. Let's not rely on that bug to
remain there.

Signed-off-by: Jan Beulich <jbeulich@suse.com>

--- a/tools/tests/x86_emulator/Makefile
+++ b/tools/tests/x86_emulator/Makefile
@@ -112,7 +112,7 @@ $(foreach flavor,$(SIMD) $(FMA),$(eval $
 
 # Also explicitly check for {evex} pseudo-prefix support, which got introduced
 # only after AVX512F and some of its extensions.
-TARGET-$(shell echo 'asm("{evex} vzeroall");' | $(CC) -x c -c -o /dev/null - || echo y) :=
+TARGET-$(shell echo 'asm("{evex} vmovaps %xmm0$(comma)%xmm0");' | $(CC) -x c -c -o /dev/null - || echo y) :=
 
 ifeq ($(TARGET-y),)
 $(warning Test harness not built, use newer compiler than "$(CC)" (version $(shell $(CC) -dumpversion)) and an "{evex}" capable assembler)

Re: [PATCH] x86emul: correct {evex} assembler capability check

[Andrew Cooper]

On 20/05/2020 15:20, Jan Beulich wrote:
> The {evex} pseudo prefix gets rejected by gas for insns not allowing
> EVEX encoding. Except there's a gas bug due to which its check gets
> bypassed for insns without operands. Let's not rely on that bug to
> remain there.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>

Acked-by: Andrew Cooper <andrew.cooper3@citrix.com>