[llvm-commits] calling convention support for ARM AAPCS VFP "homogenous aggregates"

[Bob Wilson]

Thanks for splitting it up.  I was all set to commit it for you, but  
it fails to build for me because of a compiler warning (with -Werror  
enabled):

gcc/llvm-convert.cpp: In member function 'void  
TreeToLLVM::StartFunctionBody()':
gcc/llvm-convert.cpp:446: warning: comparison between signed and  
unsigned integer expressions
gcc/llvm-convert.cpp:458: warning: comparison between signed and  
unsigned integer expressions

Those lines are the "Fn->getCallingConv() == CallingConv" assertions.
Can you investigate?

Can you also write a comment for the first patch, both to explain that  
the code is checking for variable arguments (GCC's representation of  
that is far from obvious) and to explain why you're checking for it.   
(You summarized it nicely below but there's nothing in the code.)

For future reference, for the llvm-specific C++ files in llvm-gcc, it  
seems to me like the convention is to follow the usual llvm coding  
conventions.  You had some C-style comments in llvm-arm.cpp. I've  
already gone through and changed them to C++ comments for you, so you  
don't need to do anything about it now.  I also found some typos and  
spelling issues (e.g., "homogenous" is usually spelled "homogeneous")  
that I will fix for you.

Aside from those things the patch looks good to me, so I'll commit it  
for you once we get past the build problem.

On Aug 14, 2009, at 2:06 AM, Sandeep Patel wrote:

> Attached are split versions of this patch as requested, with minor
> updates for the latest LLVM API changes applied.
>
> 1. deep-gcc-hard-float-varargs.diff applies the AAPCS base standard
> CallingConv for varargs functions, as per the spec.
> 2. deep-gcc-callingconv-id.diff is item 1 below, changing remaining
> uses of a CallingConv from unsigned to CallingConv::ID. The additional
> header inclusion is very minimal, only in llvm-internal.h.
> 3. deep-gcc-calling-conv-mixed.diff is items 2 and 3 below, tracking
> the CC in all DefaultABIClient subclasses and flowing it into
> LLVM_SHOULD_PASS_AGGREGATE_IN_MIXED_REGS and
> LLVM_AGGREGATE_PARTIALLY_PASSED_IN_REGS. This adds an include of
> CallingConv.h in llvm-abi.h, which is already includes
> llvm-internal.h.
> 4. deep-gcc-homogeneous.diff is item 4 below, adding the use of this
> stuff in the ARM backend as per the AAPCS VFP spec.
>
> deep
>
> On Fri, Aug 14, 2009 at 5:27 AM, Bob Wilson<bob.wilson at apple.com>  
> wrote:
>> Sandeep,
>>
>> This looks pretty good to me.  I have some minor comments that I  
>> will try to
>> collect in the next day or two.  I think you should split this up a  
>> bit,
>> though.  Having seen the motivation for making the CC available in  
>> more
>> contexts, it would be good to submit that as a separate patch.   
>> I.E., one
>> patch for parts 2 and 3 from your list.
>>
>> The change to use CallingConv::ID should be reviewed by someone more
>> familiar with llvm-gcc.  It looks to me like someone intentionally  
>> decided
>> to use "unsigned" to avoid pulling in the header file for  
>> CallingConv::ID,
>> and now you're changing that decision.
>>
>> On Aug 5, 2009, at 3:15 AM, Sandeep Patel wrote:
>>
>>> Attached is a patch to llvm-gcc to implement passing of homogenous
>>> aggregates via FP registers per the ARM AAPCS VFP variant (a.k.a.  
>>> hard
>>> float).
>>>
>>> 1. The patch uses CallingConv::ID consistently instead of unsigned  
>>> to
>>> hold the CC.
>>> 2. The patch keeps track of the CC in all DefaultABIClient  
>>> subclasses.
>>> 3. The patch passes the CC into
>>> LLVM_SHOULD_PASS_AGGREGATE_IN_MIXED_REGS and
>>> LLVM_AGGREGATE_PARTIALLY_PASSED_IN_REGS.
>>> 4. The patch implements both macros in the ARM backend according to
>>> the rules of the AAPCS spec.
>>>
>>> Note: no code was imported to implement this. The structure of
>>> vfp_arg_homogenous_aggregate_p was originally taken from the i386
>>> classify_argument() function.
>>>
>>> deep
>>>
>>> <deep-gcc-hard-float- 
>>> homogeneous.diff>_______________________________________________
>>> llvm-commits mailing list
>>> llvm-commits at cs.uiuc.edu
>>> http://lists.cs.uiuc.edu/mailman/listinfo/llvm-commits
>>
>>
> <deep-gcc-hard-float-varargs.diff><deep-gcc-callingconv- 
> id.diff><deep-gcc-calling-conv-mixed.diff><deep-gcc-homogeneous.diff>