Function MakeProjection

src/kudu/codegen/row_projector.cc:88–252

// kudu::RowProjector::Init() to return an error status instead.
template<bool READ>
llvm::Function* MakeProjection(const string& name,
                               ModuleBuilder* mbuilder,
                               const kudu::RowProjector& proj) {
  // Get the IRBuilder
  ModuleBuilder::LLVMBuilder* builder = mbuilder->builder();
  LLVMContext& context = builder->getContext();

  // Extract schema information from projector
  const Schema& base_schema = *proj.base_schema();
  const Schema& projection = *proj.projection();

  // Create the function after providing a declaration
  vector<Type*> argtypes = { Type::getInt8PtrTy(context),
                             PointerType::getUnqual(mbuilder->GetType("class.kudu::RowBlockRow")),
                             PointerType::getUnqual(mbuilder->GetType("class.kudu::Arena")) };
  FunctionType* fty =
    FunctionType::get(Type::getInt1Ty(context), argtypes, false);
  Function* f = mbuilder->Create(fty, name);

  // Get the function's Arguments
  Function::arg_iterator it = f->arg_begin();
  Argument* src = &*it++;
  Argument* rbrow = &*it++;
  Argument* arena = &*it++;
  DCHECK(it == f->arg_end());

  // Give names to the arguments for debugging IR.
  src->setName("src");
  rbrow->setName("rbrow");
  arena->setName("arena");

  // Mark our arguments as not aliasing. This eliminates a redundant
  // load of rbrow->row_block_ and rbrow->row_index_ for each column.
  f->addParamAttr(0, llvm::Attribute::NoAlias);
  f->addParamAttr(1, llvm::Attribute::NoAlias);
  f->addParamAttr(2, llvm::Attribute::NoAlias);

  // Project row function in IR (note: values in angle brackets are
  // constants whose values are determined right now, at JIT time).
  //
  // define i1 @name(i8* noalias %src, RowBlockRow* noalias %rbrow, Arena* noalias %arena)
  // entry:
  //   %src_bitmap = getelementptr i8* %src, i64 <offset to bitmap>
  //   <for each base column to projection column mapping>
  //     %src_cell = getelementptr i8* %src, i64 <base offset>
  //     %result = call i1 @CopyCellToRowBlock(
  //       i64 <type size>, i8* %src_cell, RowBlockRow* %rbrow,
  //       i64 <column index>, i1 <is binary>, Arena* %arena)**
  //   %success = and %success, %result***
  //   <end implicit for each>
  //   <for each projection column that needs defaults>
  //     <if default column is nullable>
  //       call void @CopyCellToRowBlockNullDefault(
  //         RowBlockRow* %rbrow, i64 <column index>, i1 <is null>)
  //     <end implicit if>
  //     <if default value was not null>
  //       %src_cell = inttoptr i64 <default value location> to i8*
  //       %result = call i1 @CopyCellToRowBlock(