[SYCL][NFC] Fix static code analysis concerns (#2789)

Found via a static-analysis tool:

1.	Inside leaveStruct()

RecordDecl *RD = Ty->getAsRecordDecl(); ---> Pointer 'RD' may be NULL
if (!RD->hasAttr<SYCLRequiresDecompositionAttr>()) ----> will be dereferenced here

2. Inside visitRecord() function, Pointer 'RecordTy->getAsRecordDecl()' returned from 
    call to function 'getAsRecordDecl' at line 
    “if (RecordTy->getAsRecordDecl()->hasAttr<SYCLRequiresDecompositionAttr>()) {“
      may be NULL and will be dereferenced at same line.


This patch fixes null pointer dereference issues in SemaSYCL.cpp file.

Signed-off-by: Soumi Manna <[email protected]>

Author: smanna12

clang/lib/Sema/SemaSYCL.cpp

@@ -1214,7 +1214,9 @@ void KernelObjVisitor::visitRecord(const CXXRecordDecl *Owner, ParentTy &Parent,
                                    const CXXRecordDecl *Wrapper,
                                    QualType RecordTy,
                                    HandlerTys &... Handlers) {
-  if (RecordTy->getAsRecordDecl()->hasAttr<SYCLRequiresDecompositionAttr>()) {
+  RecordDecl *RD = RecordTy->getAsRecordDecl();
+  assert(RD && "should not be null.");
+  if (RD->hasAttr<SYCLRequiresDecompositionAttr>()) {
     // If this container requires decomposition, we have to visit it as
     // 'complex', so all handlers are called in this case with the 'complex'
     // case.
@@ -1583,6 +1585,7 @@ class SyclKernelDecompMarker : public SyclKernelFieldHandler {
   bool leaveStruct(const CXXRecordDecl *, FieldDecl *, QualType Ty) final {
     if (CollectionStack.pop_back_val()) {
       RecordDecl *RD = Ty->getAsRecordDecl();
+      assert(RD && "should not be null.");
       if (!RD->hasAttr<SYCLRequiresDecompositionAttr>())
         RD->addAttr(SYCLRequiresDecompositionAttr::CreateImplicit(
             SemaRef.getASTContext()));
@@ -1601,6 +1604,7 @@ class SyclKernelDecompMarker : public SyclKernelFieldHandler {
                    QualType Ty) final {
     if (CollectionStack.pop_back_val()) {
       RecordDecl *RD = Ty->getAsRecordDecl();
+      assert(RD && "should not be null.");
       if (!RD->hasAttr<SYCLRequiresDecompositionAttr>())
         RD->addAttr(SYCLRequiresDecompositionAttr::CreateImplicit(
             SemaRef.getASTContext()));