[cfe-dev] OpenCL patch: vector literals (alternative patch)

[Chris Lattner]

Seems reasonable to me, but needs a testcase.

-Chris

On Jul 13, 2011, at 10:44 AM, Tanya Lattner wrote:

> Any other comments on this patch? I'd like to commit.
> 
> -Tanya
> 
> On Jul 7, 2011, at 4:41 PM, Tanya Lattner wrote:
> 
>> I'm attaching an alternative patch which handles the missing vector splat case. It passes all the valid and invalid test cases you provided and I included those tests in the patch. It also uses the fix in SemaInit that you included which handles the crash for one invalid case.
>> 
>> Thanks,
>> Tanya
>> 
>> <OpenCL-VectorLiterals.patch>
>> On Jul 7, 2011, at 8:17 AM, Anton Lokhmotov wrote:
>> 
>>> Hi Tanya,
>>> 
>>> Many thanks for your prompt review!
>>> 
>>>> All the support already exists for all the valid test cases 
>>>> except the last one ((float4)( float )). One just has to modify 
>>>> ActOnCastOfParenListExpr which is now BuildVectorLiteral to handle 
>>>> the splat case. I have not modified our patch to match the recent 
>>>> changes in TOT, but will do shortly.
>>> 
>>> We would be happy with minimal changes to Clang provided that the OpenCL
>>> requirements are properly met, including handling invalid code.  We
>>> specifically avoided using/modifying/breaking the existing functionality for
>>> AltiVec because the OpenCL syntax is quite different. Thus, we believe that
>>> for OpenCL CompilerInvocation::setLangDefaults() should disable Opts.AltiVec
>>> (and OTOH enable Opts.Bool - but sorry about that slipping into this patch).
>>> 
>>>> Yes, you are 100% right that the test violates the OpenCL spec 
>>>> (my mistake and haste in making a patch), but its catching a nasty
>>>> compiler crash and I'd rather try to modify the test instead of just
>>>> removing it. I've fixed this in TOT.
>>> 
>>> Unfortunately,
>>> 
>> 
>>> void foo( uchar8 x )
>>> {
>>> uchar4 val[4] = {{(uchar4){x.lo}}};
>>> }
>>> 
>>> is still invalid in OpenCL C.  In particular, OpenCL doesn't allow using
>>> braces {} in vector literals.
>>> 
>>> [Actually, I'm quite confused by this test.  Since x.lo produces uchar4, the
>>> cast is superfluous?  And then it attempts to initialize an array of vectors
>>> val[] from vector x.lo.  But I actually would expect only val[0] to be
>>> initialized (backed by my experiments with gcc).  But if it's just ensuring
>>> that the compiler doesn't crash, that's fine (in the AltiVec mode).]
>>> 
>>>> For the invalid cases, I don't see why one needs to modify the parser, 
>>>> but the last invalid case does crash the compiler which shouldn't ever
>>>> happen.
>>> 
>>> Could you please ensure that the patch is applied correctly?  It works fine
>>> with r134483.  Specifically, this modification prevents the compiler from
>>> crashing:
>>> 
>>> [11:17:50] Vitaly Lugovskiy: diff --git a/lib/Sema/SemaInit.cpp
>>> b/lib/Sema/SemaInit.cpp
>>> index 16ba2a2..17af145 100644
>>> --- a/lib/Sema/SemaInit.cpp
>>> +++ b/lib/Sema/SemaInit.cpp
>>> @@ -769,7 +769,8 @@ void InitListChecker::CheckSubElementType(const
>>> InitializedEntity &Entity,
>>> //   subaggregate, brace elision is assumed and the initializer is
>>> //   considered for the initialization of the first member of
>>> //   the subaggregate.
>>> -  if (ElemType->isAggregateType() || ElemType->isVectorType()) {
>>> +  if (!SemaRef.getLangOptions().OpenCL && 
>>> +      (ElemType->isAggregateType() || ElemType->isVectorType())) {
>>>   CheckImplicitInitList(Entity, IList, ElemType, Index, StructuredList,
>>>                         StructuredIndex);
>>>   ++StructuredIndex;
>>> 
>>> If you provide your modifications to support vector literals, we will run
>>> our test cases with combinatorial coverage to ensure that the OpenCL
>>> requirements are met.
>>> 
>>> Best wishes,
>>> Anton.
>>> 
>>> 
>>> 
>> 
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