[PATCH] x86: Add {load}/{store} tests for apx instructions.

[Jan Beulich]

On 03.07.2024 06:01, H.J. Lu wrote:
> On Wed, Jul 3, 2024, 10:41 AM Cui, Lili <lili.cui@intel.com> wrote:
> 
>>>> On 02.07.2024 12:29, Cui, Lili wrote:
>>>>>>>>>> Having reached the end of the file: What about CTESTcc and
>>> CCMPcc?
>>>>>>>>>>
>>>>>>>>>
>>>>>>>
>>>>>>> When adding swap test cases for CTESTcc, I found that it does not
>>>>>>> support
>>>>>> swapping operands, but test, {evex} test and ctest template insns
>>>>>> all have D, which does not match the SDM/APX spec, I want to remove
>>>>>> D for them. I'm a bit unsure if there's any particular reason why
>>>>>> the legacy test
>>>> added D ?
>>>>>>
>>>>>> Did you look at the commit doing so?
>>>>>>
>>>>>
>>>>> Ok, I found the commit this time, but I'm even more confused because
>>>>> I
>>>> didn't find the basis for the second test from SDM.
>>>>>
>>>>> -test, 0x84, None, 0, W|CheckRegSize|Modrm|No_sSuf, {
>>>>> Reg8|Reg16|Reg32|Reg64,
>>>>>
>>>>
>>> Reg8|Reg16|Reg32|Reg64|Unspecified|Byte|Word|Dword|Qword|BaseInde
>>>> x }
>>>>> -test, 0x84, None, 0, W|CheckRegSize|Modrm|No_sSuf, {
>>>>> Byte|Word|Dword|Qword|Unspecified|BaseIndex,
>>>> Reg8|Reg16|Reg32|Reg64 }
>>>>> +test, 0x84, None, 0, D|W|C|CheckRegSize|Modrm|No_sSuf, {
>>>>> +Reg8|Reg16|Reg32|Reg64,
>>>> Reg8|Reg16|Reg32|Reg64|Unspecified|BaseIndex
>>>>> +}
>>>>
>>>> "basis for the second test"? What do you mean? Are you referring to
>>>> the SDM spelling out only one operand order? That's surely a (very
>>>> minor) shortcoming there. TEST is commutative, and hence whatever
>>>> order the programmer likes should be accepted by an assembler.
>>>
>>> Yes, I only found "test %ax, (%bx)" and didn't find "test (%bx), %ax" in
>> the
>>> SDM. And APX spec also doesn’t say " ctest {def=} (%bx), %ax " is
>> supported.
>>> Anyway, their assemblers are same.
>>> I will support "ctestb(%rax),%ecx" and "{evex} test(%rax),%ecx" in
>> assembler,
>>> currently "ctestb(%rax),%ecx" does not work, I need to fix it first.
>>>
>> $ cat test.s
>> test (%edx), %eax
>> test %eax, (%edx)
>>
>> $ as --64  test.s -o test.o
>> $ objdump  -dw -Msuffix test.o
>> 0000000000000000 <_start>:
>>    0:   67 85 02                testl  %eax,(%edx)
>>    3:   67 85 02                testl  %eax,(%edx)
>>
>> Hi HJ,
>>
>> Do you remember why we supported "test (%edx), %eax" in the original
>> version? I'm curious about it.
> 
> I don't remember why.  I think we should follow SDM.

We should follow what makes sense in written code. Other assemblers
permit either order of the operands, when their order doesn't matter.
So should gas do. The fact that the SDM spells out only one order of
operands is (presumably) connected to there being only one encoding
(unlike for e.g. CMP). This does not mean we should be unfriendly to
people and force a purely stylistic restriction onto them. And just
to mention it: For TEST both forms were supported virtually forever.
Quite likely simply because, as said, other assemblers to do, too.

Jan