[clang] disable unary, vector mask (PR #130400)

[via cfe-commits]

wsehjk wrote:

In the `builtinshufflevetor2.c` test
```c++
// CHECK-LABEL: define {{.*}}void @clang_shufflevector_v_v(
void clang_shufflevector_v_v( float4* A, float4 x, uint4 mask ) {
// CHECK: [[MASK:%.*]] = and <4 x i32> {{%.*}}, splat (i32 3)
// CHECK: [[I:%.*]] = extractelement <4 x i32> [[MASK]], i{{[0-9]+}} 0
// CHECK: [[E:%.*]] = extractelement <4 x float> [[X:%.*]], i{{[0-9]+}} [[I]]
//
// Here is where ToT Clang code generation makes a mistake.  
// It uses [[I]] as the insertion index instead of 0.
// Similarly on the remaining insertelement.
// CHECK: [[V:%[a-zA-Z0-9._]+]] = insertelement <4 x float> poison, float [[E]], i{{[0-9]+}} 0

// CHECK: [[I:%.*]] = extractelement <4 x i32> [[MASK]], i{{[0-9]+}} 1
// CHECK: [[E:%.*]] = extractelement <4 x float> [[X]], i{{[0-9]+}} [[I]]
// CHECK: [[V2:%.*]] = insertelement <4 x float> [[V]], float [[E]], i{{[0-9]+}} 1
// CHECK: [[I:%.*]] = extractelement <4 x i32> [[MASK]], i{{[0-9]+}} 2
// CHECK: [[E:%.*]] = extractelement <4 x float> [[X]], i{{[0-9]+}} [[I]]
// CHECK: [[V3:%.*]] = insertelement <4 x float> [[V2]], float [[E]], i{{[0-9]+}} 2
// CHECK: [[I:%.*]] = extractelement <4 x i32> [[MASK]], i{{[0-9]+}} 3
// CHECK: [[E:%.*]] = extractelement <4 x float> [[X]], i{{[0-9]+}} [[I]]
// CHECK: [[V4:%.*]] = insertelement <4 x float> [[V3]], float [[E]], i{{[0-9]+}} 3
// CHECK: store <4 x float> [[V4]], ptr {{%.*}},
  *A = __builtin_shufflevector( x, mask );
}
```

The code will return from  `EvaluateAsRValue` in `VectorExprEvaluator::VisitShuffleVectorExpr`. So `handleVectorShuffle` will not be called, which will call `getShuffleMaskIdx`.  
```c++
bool VectorExprEvaluator::VisitShuffleVectorExpr(const ShuffleVectorExpr *E) {
  llvm::dbgs() << "VectorExprEvaluator::VisitShuffleVectorExpr called\n" ;
  APValue VecVal1;
  const Expr *Vec1 = E->getExpr(0);
  if (!EvaluateAsRValue(Info, Vec1, VecVal1))
    return false;
  APValue VecVal2;
  const Expr *Vec2 = E->getExpr(1);
  if (!EvaluateAsRValue(Info, Vec2, VecVal2))
    return false;

  VectorType const *DestVecTy = E->getType()->castAs<VectorType>();
  QualType DestElTy = DestVecTy->getElementType();

  auto TotalElementsInOutputVector = DestVecTy->getNumElements();
  llvm::dbgs() << "TotalElementsInOutputVector is " << TotalElementsInOutputVector << "\n";
  SmallVector<APValue, 4> ResultElements;
  ResultElements.reserve(TotalElementsInOutputVector);
  for (unsigned EltNum = 0; EltNum < TotalElementsInOutputVector; ++EltNum) {
    APValue Elt;
    if (!handleVectorShuffle(Info, E, DestElTy, VecVal1, VecVal2, EltNum, Elt))
      return false;
    ResultElements.push_back(std::move(Elt));
  }

  return Success(APValue(ResultElements.data(), ResultElements.size()), E);
}
```

So before the change, these failed tests passed.

https://github.com/llvm/llvm-project/pull/130400