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Re: [avr-llvm-devel] Regression tests
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From: Nicklas Bo J. <nbj...@gm...> - 2012-04-30 17:23:58
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On Mon, Apr 30, 2012 at 12:33 AM, Borja Ferrer <bor...@gm...>
wrote:
> It should be similar to what other backends do, in this case we should
> test adding with 2 regs and then with immediates values, and repeat this
> for each value type (i8, i16, i32 and i64). Checking the instruction itself
> is enough, no need to check for registers aswell, that will come in other
> tests. But when testing with imm values we should check that the imm value
> is correctly generated, so in this case ignore the reg, but check that the
> imm field is valid.
>
Ok, makes sense. I will work on creating the tests.
> And what do you mean in that you get different code between gcc and llvm?
Basically if I compile:
unsigned char add()
{
unsigned char a,b;
a = 5;
b = 7;
return a+b;
}
with avr-gcc part of the resulting assembler is:
ldi r24,lo8(5)
std Y+1,r24
ldi r24,lo8(7)
std Y+2,r24
ldd r25,Y+1
ldd r24,Y+2
add r24,r25
with clang+avr-llvm part of the resulting assembler is:
ldi r24, 5
std Y+2, r24
ldi r24, 7
std Y+1, r24
ldd r24, Y+2
adiw r25:r24, 7
andi r24, 255
andi r25, 0
So they use different approaches(add and adiw) to solve the same problem.
Thanks
Nicklas
2012/4/29 Nicklas Bo Jensen <nbj...@gm...>
>
>> Sure. Just wanted to actually compile the code before writing tests.
>>
>> Got how the test framework works and added a very small test that is
>> working perfectly.
>>
>> How detailed should the test be? Should it check the generated assembly
>> fully or just the main parts, e.g. the addition itself? For an addition the
>> avr-llvm version is quite different from the avr-gcc version.
>>
>> Thanks,
>> Nicklas
>>
>>
>>
>> On Sun, Apr 29, 2012 at 8:07 PM, Borja Ferrer <bor...@gm...>wrote:
>>
>>> The problem here is that I've represented register pairs as r29:r28
>>> while the assembler only wants the low register of the pair, that's why
>>> you're getting that error but you're doing it right.
>>>
>>> But the way of writing regression tests in llvm is different to what
>>> you're doing. Those tests in SVN are going away once we start writing the
>>> new ones.
>>>
>>> Read this: http://llvm.org/docs/TestingGuide.html
>>> and then go to
>>> http://llvm.org/viewvc/llvm-project/llvm/trunk/test/CodeGen/ and choose
>>> any target you wish (say msp430 since it's the most similar one to us) to
>>> see how real tests look like.
>>>
>>> Basically, you have to write a test in llvm assembly, and then with
>>> CHECK you write the avr assembly that should be emitted, if it matches then
>>> the test passes otherwise it fails. You can avoid writing the llvm assembly
>>> by writing the test in C and then translate it to llvm assembly with clang.
>>>
>>> Try writing a small test for add using the llvm testing infrastructure
>>> and then run it with llvm to see if it passes.
>>> It's very important that you write the expected output assembly right,
>>> otherwise we'll generate wrong code to make the test pass, but since tests
>>> are quite small it's easy to get it right.
>>>
>>>
>>> 2012/4/29 Nicklas Bo Jensen <nbj...@gm...>
>>>
>>>> Hi,
>>>>
>>>> I have successfully been able to compile your testcases
>>>> (/avr-llvm/testcases/*.ll) to something looking like valid avr assembler.
>>>>
>>>> How should I test/simulate the assembler? I get errors when trying to
>>>> simulate the generated assembler in AVRStudio. Perhaps they use a different
>>>> assembler?
>>>>
>>>> For one test, add1.ll I cannot process it using avr-as. I have done:
>>>>
>>>> ../../build/Debug+Asserts/bin/llc --march=avr add1.ll -o add1.s
>>>> avr-as -mmcu=atmega168 add1.s
>>>>
>>>>
>>>> and get the error:
>>>>
>>>> asm.s: Assembler messages:
>>>> asm.s:12: Error: register r24, r26, r28 or r30 required
>>>> asm.s:12: Error: `,' required
>>>> asm.s:12: Error: garbage at end of line
>>>> asm.s:24: Error: register r24, r26, r28 or r30 required
>>>> asm.s:24: Error: `,' required
>>>> asm.s:24: Error: garbage at end of line
>>>>
>>>>
>>>> Am I doing something wrong? I have included the assembler.
>>>>
>>>> Thanks,
>>>> Nicklas
>>>>
>>>> On Sun, Apr 29, 2012 at 7:23 PM, Borja Ferrer <bor...@gm...>wrote:
>>>>
>>>>> Hello Neil I'm replying you in this thread, i dont know why I didn't
>>>>> receive your mail, i had to look in SF to read it.
>>>>>
>>>>> Anyways, first try to build the backend so you can play a bit with it
>>>>> to get familiar with its code. Try compiling some C code to generate avr
>>>>> assembly.
>>>>>
>>>>> 2012/4/23 Nicklas Bo Jensen <nbj...@gm...>
>>>>>
>>>>>> Hi,
>>>>>>
>>>>>> I'll be happy to contribute, after I have fixed my issues getting
>>>>>> avr-llvm to compile in the first place.
>>>>>>
>>>>>> BR,
>>>>>> Nicklas
>>>>>>
>>>>>> On Sun, Apr 22, 2012 at 7:26 PM, Borja Ferrer <bor...@gm...>wrote:
>>>>>>
>>>>>>> I think it's time to stop adding more features until we cover what
>>>>>>> is currently implemented with regression tests. Otherwise the further we go
>>>>>>> the harder will be to cover everything up, from now on it's going to be
>>>>>>> easier to go in parallel.
>>>>>>> In the past emails I've seen people interested in helping out with
>>>>>>> this, it's a good way of starting with some development becuase it's an
>>>>>>> easy task to do and it helps to understand how llvm works, so anybody
>>>>>>> interested check in here so I know if I'm going to have any help at all or
>>>>>>> I have to do it myself.
>>>>>>>
>>>>>>> So if there's some help available we can plan in this thread what
>>>>>>> needs to get covered and how to do it, I'll wait a few days for any replies.
>>>>>>>
>>>>>>>
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>>>>>>>
>>>>>>>
>>>>>>
>>>>>
>>>>>
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