r230971 - CodeGen: Fix passing of classes with only one AVX vector member in AVX registers

[Dimitry Andric]

A good candidate for 3.6.1? :)

-Dimitry

> On 02 Mar 2015, at 17:09, Benjamin Kramer <benny.kra at googlemail.com> wrote:
> 
> Author: d0k
> Date: Mon Mar  2 10:09:24 2015
> New Revision: 230971
> 
> URL: http://llvm.org/viewvc/llvm-project?rev=230971&view=rev
> Log:
> CodeGen: Fix passing of classes with only one AVX vector member in AVX registers
> 
> isSingleElementStruct was a bit too tight in its definition of struct
> so we got a mismatch between classify() and the actual code generation.
> To make matters worse the code in GetByteVectorType still defaulted to
> <2 x double> if it encountered a type it didn't know, making this a
> silent miscompilation (PR22753).
> 
> Completely remove the "preferred type" stuff from GetByteVectorType and
> make it fail an assertion if someone tries to use it with a type not
> suitable for a vector register.
> 
> Added:
>    cfe/trunk/test/CodeGenCXX/x86_64-arguments-avx.cpp
> Modified:
>    cfe/trunk/lib/CodeGen/TargetInfo.cpp
> 
> Modified: cfe/trunk/lib/CodeGen/TargetInfo.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/CodeGen/TargetInfo.cpp?rev=230971&r1=230970&r2=230971&view=diff
> ==============================================================================
> --- cfe/trunk/lib/CodeGen/TargetInfo.cpp (original)
> +++ cfe/trunk/lib/CodeGen/TargetInfo.cpp Mon Mar  2 10:09:24 2015
> @@ -238,7 +238,7 @@ static bool isEmptyRecord(ASTContext &Co
> /// \return The field declaration for the single non-empty field, if
> /// it exists.
> static const Type *isSingleElementStruct(QualType T, ASTContext &Context) {
> -  const RecordType *RT = T->getAsStructureType();
> +  const RecordType *RT = T->getAs<RecordType>();
>   if (!RT)
>     return nullptr;
> 
> @@ -2210,20 +2210,9 @@ llvm::Type *X86_64ABIInfo::GetByteVector
>     Ty = QualType(InnerTy, 0);
> 
>   llvm::Type *IRType = CGT.ConvertType(Ty);
> -
> -  // If the preferred type is a 16-byte vector, prefer to pass it.
> -  if (llvm::VectorType *VT = dyn_cast<llvm::VectorType>(IRType)){
> -    llvm::Type *EltTy = VT->getElementType();
> -    unsigned BitWidth = VT->getBitWidth();
> -    if ((BitWidth >= 128 && BitWidth <= 256) &&
> -        (EltTy->isFloatTy() || EltTy->isDoubleTy() ||
> -         EltTy->isIntegerTy(8) || EltTy->isIntegerTy(16) ||
> -         EltTy->isIntegerTy(32) || EltTy->isIntegerTy(64) ||
> -         EltTy->isIntegerTy(128)))
> -      return VT;
> -  }
> -
> -  return llvm::VectorType::get(llvm::Type::getDoubleTy(getVMContext()), 2);
> +  assert(isa<llvm::VectorType>(IRType) &&
> +         "Trying to return a non-vector type in a vector register!");
> +  return IRType;
> }
> 
> /// BitsContainNoUserData - Return true if the specified [start,end) bit range
> 
> Added: cfe/trunk/test/CodeGenCXX/x86_64-arguments-avx.cpp
> URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/test/CodeGenCXX/x86_64-arguments-avx.cpp?rev=230971&view=auto
> ==============================================================================
> --- cfe/trunk/test/CodeGenCXX/x86_64-arguments-avx.cpp (added)
> +++ cfe/trunk/test/CodeGenCXX/x86_64-arguments-avx.cpp Mon Mar  2 10:09:24 2015
> @@ -0,0 +1,15 @@
> +// RUN: %clang_cc1 -triple x86_64-unknown-unknown -emit-llvm -o - %s -target-feature +avx | FileCheck %s
> +
> +namespace test1 {
> +typedef double __m256d __attribute__((__vector_size__(32)));
> +
> +class PR22753 {
> +public:
> +  __m256d data;
> +};
> +
> +// CHECK: define <4 x double> @_ZN5test14testENS_7PR22753E(<4 x double>
> +PR22753 test(PR22753 x) {
> +  return x;
> +}
> +}
> 
> 
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