Method CreateStructValFromReadWriteInfo

be/src/codegen/codegen-anyval.cc:854–927

Returns the last block generated so we can set it as a predecessor in PHI nodes.

// Returns the last block generated so we can set it as a predecessor in PHI nodes.
llvm::BasicBlock* CodegenAnyVal::CreateStructValFromReadWriteInfo(
    const CodegenAnyValReadWriteInfo& read_write_info,
    llvm::Value** ptr, llvm::Value** len, llvm::BasicBlock* struct_produce_value_block) {
  LlvmCodeGen* codegen = read_write_info.codegen();
  LlvmBuilder* builder = read_write_info.builder();

  DCHECK(read_write_info.type().IsStructType() && read_write_info.children().size() > 0);
  DCHECK(read_write_info.GetEval() != nullptr);
  DCHECK_GT(read_write_info.GetFnCtxIdx(), -1);

  // Cross-compiled functions this hand-crafted function will call.
  llvm::Function* const allocate_for_results_fn =
         codegen->GetFunction(IRFunction::FN_CTX_ALLOCATE_FOR_RESULTS, false);
  llvm::Function* const store_result_in_eval_fn =
         codegen->GetFunction(IRFunction::STORE_RESULT_IN_EVALUATOR, false);

  builder->SetInsertPoint(read_write_info.non_null_block());
  std::size_t num_children = read_write_info.children().size();
  DCHECK_GT(num_children, 0);
  llvm::Value* fn_ctx = read_write_info.CodegenGetFnCtx();

  // Allocate a buffer for the child pointers. If allocation fails, the struct will be
  // null.
  llvm::Value* children_ptrs_buffer = builder->CreateCall(allocate_for_results_fn,
      {fn_ctx, codegen->GetI64Constant(num_children * sizeof(uint8_t*))},
      "children_ptrs_buffer");
  llvm::Value* cast_children_ptrs_buffer = builder->CreateBitCast(
      children_ptrs_buffer, codegen->ptr_ptr_type(), "cast_children_ptrs_buffer");
  llvm::Value* buffer_is_null = builder->CreateIsNull(
      cast_children_ptrs_buffer, "buffer_is_null");

  // Branch based on 'buffer_is_null'.
  read_write_info.children()[0].entry_block().BranchToIfNot(builder, buffer_is_null,
      NonWritableBasicBlock(read_write_info.null_block()));
  for (std::size_t i = 0; i < num_children; ++i) {
    const CodegenAnyValReadWriteInfo& child_codegen_value_read_write_info =
        read_write_info.children()[i];
    CodegenAnyVal child_any_val =
        CreateFromReadWriteInfo(child_codegen_value_read_write_info);

    llvm::ConstantStruct* child_type_ir =
        child_codegen_value_read_write_info.GetIrType();
    llvm::Value* child_type_ir_ptr = codegen->CreateEntryBlockAlloca(
        *builder, child_type_ir->getType(), "child_type_ptr");
    builder->CreateStore(child_type_ir, child_type_ir_ptr);

    llvm::Value* child_any_val_ptr = child_any_val.GetAnyValPtr("child_ptr");

    // Convert and store the child in the corresponding ScalarExprEvaluator - this takes
    // care of the lifetime of the object.
    llvm::Value* stored_child_ptr = builder->CreateCall(store_result_in_eval_fn,
        {child_codegen_value_read_write_info.GetEval(), child_any_val_ptr,
        child_type_ir_ptr},
        "stored_value");

    // The address where the child pointer should be written. This is in the pointer list
    // of the StructVal.
    llvm::Value* dst_child_ptr_addr = builder->CreateInBoundsGEP(