Method CodegenEval

be/src/exec/filter-context.cc:189–268

An example of the generated code for the following query: select a.outer_struct, b.small_struct from functional_orc_def.complextypes_nested_structs a inner join functional_orc_def.complextypes_structs b on b.small_struct.i = a.outer_struct.inner_struct2.i + 19091; define i1 @FilterContextEval(%"struct.impala::FilterContext"* %this, %"class.impala::TupleRow"* %row) #50 { entry: %0 = alloca i64 %e

//   ret i1 %passed_filter
// }
Status FilterContext::CodegenEval(
    LlvmCodeGen* codegen, ScalarExpr* filter_expr, llvm::Function** fn) {
  llvm::LLVMContext& context = codegen->context();
  LlvmBuilder builder(context);

  *fn = nullptr;
  llvm::PointerType* this_type = codegen->GetStructPtrType<FilterContext>();
  llvm::PointerType* tuple_row_ptr_type = codegen->GetStructPtrType<TupleRow>();
  LlvmCodeGen::FnPrototype prototype(codegen, "FilterContextEval",
      codegen->bool_type());
  prototype.AddArgument(LlvmCodeGen::NamedVariable("this", this_type));
  prototype.AddArgument(LlvmCodeGen::NamedVariable("row", tuple_row_ptr_type));

  llvm::Value* args[2];
  llvm::Function* eval_filter_fn = prototype.GeneratePrototype(&builder, args);
  llvm::Value* this_arg = args[0];
  llvm::Value* row_arg = args[1];

  llvm::Function* compute_fn;
  RETURN_IF_ERROR(filter_expr->GetCodegendComputeFn(codegen, false, &compute_fn));
  DCHECK(compute_fn != nullptr);

  // The function for checking against the bloom filter for match.
  llvm::Function* runtime_filter_fn =
      codegen->GetFunction(IRFunction::RUNTIME_FILTER_EVAL, false);
  DCHECK(runtime_filter_fn != nullptr);

  // Load 'expr_eval' from 'this_arg' FilterContext object.
  llvm::Value* expr_eval_ptr =
      builder.CreateStructGEP(nullptr, this_arg, 0, "expr_eval_ptr");
  llvm::Value* expr_eval_arg = builder.CreateLoad(expr_eval_ptr, "expr_eval_arg");

  // Evaluate the row against the filter's expression.
  llvm::Value* compute_fn_args[] = {expr_eval_arg, row_arg};
  CodegenAnyVal result = CodegenAnyVal::CreateCallWrapped(codegen, &builder,
      filter_expr->type(), compute_fn, compute_fn_args, "result");

  CodegenAnyValReadWriteInfo rwi = result.ToReadWriteInfo();
  rwi.entry_block().BranchTo(&builder);

  llvm::BasicBlock* eval_filter_block =
      llvm::BasicBlock::Create(context, "eval_filter", eval_filter_fn);

  // Set the pointer to NULL in case it evaluates to NULL.
  builder.SetInsertPoint(rwi.null_block());
  llvm::Value* null_ptr = codegen->null_ptr_value();
  builder.CreateBr(eval_filter_block);

  // Saves 'result' on the stack and passes a pointer to it to 'runtime_filter_fn'.
  builder.SetInsertPoint(rwi.non_null_block());
  llvm::Value* native_ptr = SlotDescriptor::CodegenStoreNonNullAnyValToNewAlloca(rwi);
  native_ptr = builder.CreatePointerCast(native_ptr, codegen->ptr_type(), "native_ptr");
  builder.CreateBr(eval_filter_block);

  // Get the arguments in place to call 'runtime_filter_fn' to see if the row passes.
  builder.SetInsertPoint(eval_filter_block);
  llvm::PHINode* val_ptr_phi = rwi.CodegenNullPhiNode(native_ptr, null_ptr,
      "val_ptr_phi");