Re: [avr-llvm-devel] Inline assembly. Mostly just a stub.

[Borja F. <bor...@gm...>]

Ahh, I didn't know avr-gcc was buggy on this feature, that's probably the
reason for why the code i pasted in my previous email didn't work.

About the getPointerRegClass function, what is it used for? Also, please
move the implementation to the cpp file instead of leaving it in the .h.

Ok tests look good, looking at what you covered is there anything else that
needs to be implemented for this constraint?

What's wrong with clang? I fixed clang inline asm support back on friday,
so is there anything else that is broken?



2013/6/25 Stepan Dyatkovskiy <stp...@na...>

> Hi Borja.
> This is new patch. Seems I've moved memory constraint implementation to
> the same level like all other constraints. Note avr-gcc has buggy
> implementation of memory constraint, that's why *avr-libc doesn't use it*.
>
> I removed restriction for Y,Z in getLargestLegalSuperClass, so these
> registers could be inflated now. But there was unimplemented
> getPointerRegClass method in AVRRegistersInfo. So currently I have
> restricted it to Y and Z. Though suppose we can extend it in future to XYZ
> set.
> Look changes in inline-asm.ll to see what exactly is supported now.
>
> About clang.
> May be we ask John Myers to fix clang support for inline asm?
>
> -Stepan.
>
>
> Stepan Dyatkovskiy wrote:
>
>> The patch. Forgot to attach it.
>> -Stepan.
>> Stepan Dyatkovskiy wrote:
>>
>>> Hi Borja,
>>>
>>>  > What happens in your example above when you use a real instruction
>>> like
>>>
>>>> for example LDD? Does it still use GPR8 regs? To me it's weird that if
>>>> you use a real instruction where operands are clearly defined in the td
>>>> file the instruction selector uses  an invalid regclass.
>>>>
>>>
>>> There are two kinds of inline asm support in LLVM:
>>> 1. You just support all the constraints and pastes inline-asm contents
>>> as-is. That's why its still allowed to use names like "some_instr".
>>> 2. You may expand inline-asm strings set, or in another words just parse
>>> it onto set of instructions. In this case you have to implement
>>> TargetLowering::**ExpandInlineAsm method.
>>> I'd want to start it on this week though...
>>>
>>> But first we have to get avr-libc compilable (perhpas I read you
>>> thoughts ;-) )
>>>
>>> Relative to memory constrains. I implemented initial version it can
>>> catch simplest cases (from test-case):
>>>
>>> @a = internal global i16 0, align 4
>>> @b = internal global i16 0, align 4
>>> define void @mem() {
>>>    ;CHECK: some_instr Z, Y
>>>    call void asm "some_instr $0, $1", "=*Q,=*Q"(i16* @a, i16* @b)
>>>    ret void
>>> }
>>>
>>> The patch is attached.
>>>
>>> Its in my todo yet, to handle local variables. They could be emitted as
>>> Y+q expression. Hope to present this support tomorrow. So if 'a' and 'b'
>>> from example above would be local we could get "some_instr Y, Y+2"
>>>
>>> -Stepan.
>>>
>>>
>>>
>>
>