On Mar 18, 2011, at 11:16 PM, Anton Yartsev wrote:
> Thanks for the review!
>> Index: lib/CodeGen/CGExprConstant.cpp
>>
>> ===================================================================
>> --- lib/CodeGen/CGExprConstant.cpp (revision 124983)
>> +++ lib/CodeGen/CGExprConstant.cpp (working copy)
>> @@ -907,12 +907,29 @@
>>
>> llvm::SmallVector<llvm::Constant *, 4> Inits;
>> unsigned NumElts = Result.Val.getVectorLength();
>>
>> - for (unsigned i = 0; i != NumElts; ++i) {
>> - APValue&Elt = Result.Val.getVectorElt(i);
>> - if (Elt.isInt())
>> - Inits.push_back(llvm::ConstantInt::get(VMContext, Elt.getInt()));
>> - else
>> - Inits.push_back(llvm::ConstantFP::get(VMContext, Elt.getFloat()));
>> + if (Context.getLangOptions().AltiVec&&
>> + isa<CStyleCastExpr>(E)&&
>> + dyn_cast<CStyleCastExpr>(E)->getCastKind() == CK_VectorSplat) {
>>
>> Why check for a C-style cast here? Why not just check for a (general)
>> CastExpr, which would also cover C-style casts (e.g., static_cast) and
>> implicit casts?
> The goal of this 'if' is to detect an AltiVec vector initialization with a
> single literal and I know that it should be exactly CStyleCastExpr:
> Index: lib/Sema/SemaExpr.cpp
> ===================================================================
> .....
> + if (PE->getNumExprs() == 1) {
> .....
> + return BuildCStyleCastExpr(LParenLoc, TInfo, RParenLoc, Literal);
> + }
That's not actually an answer to my question, although perhaps I didn't
formulate the question well :)
In C++, should I be able to write a functional-style cast to an AltiVec vector
with a single literal? Given that C++ considers functional-style and C-style
casts to be equivalent when there's only one argument, I think that we should.
Should static_cast also work? For that, it might depend on what GCC does.
>> Also, one little nit: if you've already done an isa<T>(X), you can just
>> cast<T>(X) rather than dyn_cast<T>(X), and save ourselves some checking.
> corrected!
>
> Can I commit the patch?
I'd prefer that CodeGen just check for a CastExpr with kind CK_VectorSplat;
CodeGen isn't supposed to consider syntax. With that tweak, please go ahead.
- Doug
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