[cfe-commits] [llvm-commits] [PATCH] ARM ABI: handle varargs with vector types.
Manman Ren
mren at apple.com
Mon Oct 15 17:38:29 PDT 2012
On Oct 15, 2012, at 5:34 PM, Eli Friedman wrote:
> On Mon, Oct 15, 2012 at 5:26 PM, Manman Ren <mren at apple.com> wrote:
>>
>> On Oct 15, 2012, at 5:11 PM, Eli Friedman wrote:
>>
>>> On Mon, Oct 15, 2012 at 4:46 PM, manman ren <mren at apple.com> wrote:
>>>>
>>>> The initial patch was updated and separated to two patches (attached).
>>>>
>>>> The first patch will fix passing legal vector types as varargs:
>>>> We make sure the vector is correctly aligned before casting it to the vector type.
>>>
>>> + uint64_t Size = CGF.getContext().getTypeSize(Ty) / 8;
>>> + uint64_t TyAlign = CGF.getContext().getTypeAlign(Ty) / 8;
>>> +
>>> + // The ABI alignment for vectors is 8 for AAPCS and 4 for APCS.
>>> + if (Ty->getAs<VectorType>() && Size >= 8) {
>>> + if (getABIKind() == ARMABIInfo::AAPCS_VFP ||
>>> + getABIKind() == ARMABIInfo::AAPCS)
>>> + TyAlign = 8;
>>> + else
>>> + TyAlign = 4;
>>> + }
>>>
>>> We should be using the same rules here we do for argument passing. In
>>> particular, for APCS, the argument-passing type alignment is
>>> unconditionally 4. (This can have effects for structs marked with
>>> "__attribute__((aligned(16)))", etc.)
>> Is there an interface to query the argument-passing alignment?
>
> Nothing cares about it other than the calling convention code, so
> there isn't a general API. It's basically just "match whatever
> ARMABIInfo::classifyArgumentType does".
I don't see code in ARMABIInfo::classifyArgumentType that checks the argument-passing alignment.
The code in the patch is trying to match what the calling convention does in the backend:
>>> + // The ABI alignment for vectors is 8 for AAPCS and 4 for APCS.
>>> + if (Ty->getAs<VectorType>() && Size >= 8) {
>>> + if (getABIKind() == ARMABIInfo::AAPCS_VFP ||
>>> + getABIKind() == ARMABIInfo::AAPCS)
>>> + TyAlign = 8;
>>> + else
>>> + TyAlign = 4;
>>> + }
Thanks,
Manman
>
> -Eli
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