[LLVMdev] Using CallingConvLower in ARM target

[Sandeep Patel]

I think I've got all the cases handled now, implementing with
CCCustom<"foo"> callbacks into C++.

This also fixes a crash when returning i128. I've also included a
small asm constraint fix that was needed to build newlib.

deep

On Mon, Jan 19, 2009 at 10:18 AM, Evan Cheng <evan.cheng at apple.com> wrote:
>
> On Jan 16, 2009, at 5:26 PM, Sandeep Patel wrote:
>
>> On Sat, Jan 3, 2009 at 11:46 AM, Dan Gohman <gohman at apple.com> wrote:
>>>
>>> One problem with this approach is that since i64 isn't legal, the
>>> bitcast would require custom C++ code in the ARM target to
>>> handle properly.  It might make sense to introduce something
>>> like
>>>
>>>   CCIfType<[f64], CCCustom>
>>>
>>> where CCCustom is a new entity that tells the calling convention
>>> code to to let the target do something not easily representable
>>> in the tablegen minilanguage.
>>
>> I am thinking that this requires two changes: add a flag to
>> CCValAssign (take a bit from HTP) to indicate isCustom and a way to
>> author an arbitrary CCAction by including the source directly in the
>> TableGen mini-language. This latter change might want a generic change
>> to the TableGen language. For example, the syntax might be like:
>>
>> class foo : CCCustomAction {
>> code <<< EOF
>>      ....multi-line C++ code goes here that allocates regs & mem and
>> sets CCValAssign::isCustom....
>> EOF
>> }
>>
>> Does this seem reasonable? An alternative is for CCCustom to take a
>> string that names a function to be called:
>>
>> CCIfType<[f64], CCCustom<"MyCustomLoweringFunc">>
>>
>> the function signature for such functions will have to return two
>> results: if the CC processing is finished and if it the func succeeded
>> or failed:
>
> I like the second solution better. It seems rather cumbersome to embed
> multi-line c++ code in td files.
>
> Evan
>>
>>
>> typedef bool CCCustomFn(unsigned ValNo, MVT ValVT,
>>                        MVT LocVT, CCValAssign::LocInfo LocInfo,
>>                        ISD::ArgFlagsTy ArgFlags, CCState &State,
>> bool &result);
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