rever changes to CGExprScalar.cpp as the suggestion was a missunderstanding. fix up some typos

Author: farzonl

clang/lib/CodeGen/CGExprScalar.cpp

@@ -2977,26 +2977,27 @@ Value *ScalarExprEmitter::VisitCastExpr(CastExpr *CE) {
     return Builder.CreateExtractElement(Vec, Zero, "cast.vtrunc");
   }
   case CK_HLSLMatrixTruncation: {
-    assert((DestTy->isConstantMatrixType() || DestTy->isBuiltinType()) &&
+    assert((DestTy->isMatrixType() || DestTy->isBuiltinType()) &&
            "Destination type must be a matrix or builtin type.");
     Value *Mat = Visit(E);
-    unsigned NumCols = 1;
-    unsigned NumRows = 1;
-    SmallVector<int> Mask;
     if (auto *MatTy = DestTy->getAs<ConstantMatrixType>()) {
-      NumCols = MatTy->getNumColumns();
-      NumRows = MatTy->getNumRows();
-    }
-    unsigned ColOffset = NumCols;
-    if (auto *SrcMatTy = E->getType()->getAs<ConstantMatrixType>())
-      ColOffset = SrcMatTy->getNumColumns();
-    for (unsigned R = 0; R < NumRows; R++) {
-      for (unsigned C = 0; C < NumCols; C++) {
-        unsigned I = R * ColOffset + C;
-        Mask.push_back(I);
+      SmallVector<int> Mask;
+      unsigned NumCols = MatTy->getNumColumns();
+      unsigned NumRows = MatTy->getNumRows();
+      unsigned ColOffset = NumCols;
+      if (auto *SrcMatTy = E->getType()->getAs<ConstantMatrixType>())
+        ColOffset = SrcMatTy->getNumColumns();
+      for (unsigned R = 0; R < NumRows; R++) {
+        for (unsigned C = 0; C < NumCols; C++) {
+          unsigned I = R * ColOffset + C;
+          Mask.push_back(I);
+        }
       }
+
+      return Builder.CreateShuffleVector(Mat, Mask, "trunc");
     }
-    return Builder.CreateShuffleVector(Mat, Mask, "trunc");
+    llvm::Value *Zero = llvm::Constant::getNullValue(CGF.SizeTy);
+    return Builder.CreateExtractElement(Mat, Zero, "cast.mtrunc");
   }
   case CK_HLSLElementwiseCast: {
     RValue RV = CGF.EmitAnyExpr(E);

clang/lib/Sema/SemaChecking.cpp

@@ -12590,7 +12590,7 @@ void Sema::CheckImplicitConversion(Expr *E, QualType T, SourceLocation CC,
     Source = cast<VectorType>(Source)->getElementType().getTypePtr();
     Target = cast<VectorType>(Target)->getElementType().getTypePtr();
   }
-  if (auto VecTy = dyn_cast<VectorType>(Target))
+  if (const auto *VecTy = dyn_cast<VectorType>(Target))
     Target = VecTy->getElementType().getTypePtr();
 
   if (isa<ConstantMatrixType>(Source)) {

clang/lib/Sema/SemaOverload.cpp

@@ -2121,7 +2121,7 @@ static bool IsMatrixConversion(Sema &S, QualType FromType, QualType ToType,
   auto *ToMatrixType = ToType->getAs<ConstantMatrixType>();
   auto *FromMatrixType = FromType->getAs<ConstantMatrixType>();
 
-  // If both arguments are vectors, handle possible vector truncation and
+  // If both arguments are matrix, handle possible matrix truncation and
   // element conversion.
   if (ToMatrixType && FromMatrixType) {
     unsigned FromCols = FromMatrixType->getNumColumns();