Function CodegenStringTest

be/src/codegen/llvm-codegen-test.cc:383–421

Test function for c++/ir interop for strings. Function will do: int StringTest(StringValue* strval) { strval->ptr[0] = 'A'; int len = strval->len; strval->len = 1; return len; } Corresponding IR is: define i32 @StringTest(%StringValue* %str) { entry: %str_ptr = getelementptr inbounds %StringValue* %str, i32 0, i32 0 %ptr = load i8** %str_ptr %first_char_ptr = getelementptr i8* %ptr, i32 0 store i

//   ret i32 %len
// }
llvm::Function* CodegenStringTest(LlvmCodeGen* codegen) {
  llvm::PointerType* string_val_ptr_type =
      codegen->GetSlotPtrType(ColumnType(TYPE_STRING));
  EXPECT_TRUE(string_val_ptr_type != NULL);

  LlvmCodeGen::FnPrototype prototype(codegen, "StringTest", codegen->i32_type());
  prototype.AddArgument(LlvmCodeGen::NamedVariable("str", string_val_ptr_type));
  LlvmBuilder builder(codegen->context());

  llvm::Value* str;
  llvm::Function* interop_fn = prototype.GeneratePrototype(&builder, &str);

  // strval->ptr[0] = 'A'
  llvm::Function* str_ptr_fn = codegen->GetFunction(
      IRFunction::STRING_VALUE_PTR, false);
  llvm::Function* str_len_fn = codegen->GetFunction(
      IRFunction::STRING_VALUE_LEN, false);
  llvm::Function* str_setlen_fn = codegen->GetFunction(
      IRFunction::STRING_VALUE_SETLEN, false);

  llvm::Value* str_ptr = builder.CreateCall(str_ptr_fn,
      llvm::ArrayRef<llvm::Value*>({str}), "ptr");

  llvm::Value* first_char_offset[] = {codegen->GetI32Constant(0)};
  llvm::Value* first_char_ptr =
      builder.CreateGEP(str_ptr, first_char_offset, "first_char_ptr");
  builder.CreateStore(codegen->GetI8Constant('A'), first_char_ptr);

  // Update and return old len
  llvm::Value* str_len = builder.CreateCall(str_len_fn,
      llvm::ArrayRef<llvm::Value*>({str}), "len");

  builder.CreateCall(str_setlen_fn,
      llvm::ArrayRef<llvm::Value*>({str, codegen->GetI32Constant(1)}));

  builder.CreateRet(str_len);

  return codegen->FinalizeFunction(interop_fn);
}

// This test validates that the llvm StringValue struct matches the c++ stringvalue
// struct.  Just create a simple StringValue struct and make sure the IR can read it