Method CodegenEvalRow

be/src/exec/hash-table.cc:871–990

Codegen for evaluating a tuple row over either build_expr_evals_ or probe_expr_evals_. Below is the IR generated for the following query: select bigint_col, string_col from functional.alltypestiny group by bigint_col, string_col; define i1 @EvalProbeRow(%"class.impala::HashTableCtx"* %this_ptr, %"class.impala::TupleRow"* %row, i8* %expr_values, i8* %expr_values_null) #53 { entry: %eval_vector =

//   ret i1 %has_null14
// }
Status HashTableCtx::CodegenEvalRow(LlvmCodeGen* codegen, bool build_row,
    const HashTableConfig& config, llvm::Function** fn) {
  const std::vector<ScalarExpr*>& exprs =
      build_row ? config.build_exprs : config.probe_exprs;
  const ScalarExprsResultsRowLayout& result_row_layout =
      config.build_exprs_results_row_layout;
  for (int i = 0; i < exprs.size(); ++i) {
    // Disable codegen for CHAR
    if (exprs[i]->type().type == TYPE_CHAR) {
      return Status("HashTableCtx::CodegenEvalRow(): CHAR NYI");
    }
  }

  // Get types to generate function prototype
  llvm::PointerType* this_ptr_type = codegen->GetStructPtrType<HashTableCtx>();
  llvm::PointerType* tuple_row_ptr_type = codegen->GetStructPtrType<TupleRow>();
  LlvmCodeGen::FnPrototype prototype(
      codegen, build_row ? "EvalBuildRow" : "EvalProbeRow", codegen->bool_type());
  prototype.AddArgument(LlvmCodeGen::NamedVariable("this_ptr", this_ptr_type));
  prototype.AddArgument(LlvmCodeGen::NamedVariable("row", tuple_row_ptr_type));
  prototype.AddArgument(LlvmCodeGen::NamedVariable("expr_values", codegen->ptr_type()));
  prototype.AddArgument(
      LlvmCodeGen::NamedVariable("expr_values_null", codegen->ptr_type()));

  llvm::LLVMContext& context = codegen->context();
  LlvmBuilder builder(context);
  llvm::Value* args[4];
  *fn = prototype.GeneratePrototype(&builder, args);
  llvm::Value* this_ptr = args[0];
  llvm::Value* row = args[1];
  llvm::Value* expr_values = args[2];
  llvm::Value* expr_values_null = args[3];
  llvm::Value* has_null = codegen->false_value();

  // evaluator_vector = build_expr_evals_.data() / probe_expr_evals_.data()
  llvm::Value* eval_vector = codegen->CodegenCallFunction(&builder,
      build_row ? IRFunction::HASH_TABLE_GET_BUILD_EXPR_EVALUATORS :
                  IRFunction::HASH_TABLE_GET_PROBE_EXPR_EVALUATORS,
      this_ptr, "eval_vector");

  DCHECK_EQ(exprs.size(), result_row_layout.expr_values_offsets.size());
  for (int i = 0; i < exprs.size(); ++i) {
    // TODO: refactor this to somewhere else?  This is not hash table specific except for
    // the null handling bit and would be used for anyone that needs to materialize a
    // vector of exprs
    // Convert result buffer to llvm ptr type
    int offset = result_row_layout.expr_values_offsets[i];
    llvm::Value* loc = builder.CreateInBoundsGEP(
        NULL, expr_values, codegen->GetI32Constant(offset), "loc_addr");
    llvm::Value* llvm_loc =
        builder.CreatePointerCast(loc, codegen->GetSlotPtrType(exprs[i]->type()), "loc");

    // Call expr
    llvm::Function* expr_fn;
    Status status = exprs[i]->GetCodegendComputeFn(codegen, false, &expr_fn);
    if (!status.ok()) {
      *fn = NULL;
      return Status(Substitute(