// Standard register names.
	for i := riscv.REG_X0; i <= riscv.REG_X31; i++ {
		// Disallow X3 in shared mode, as this will likely be used as the
		// GP register, which could result in problems in non-Go code,
		// including signal handlers.
		if shared && i == riscv.REG_GP {
			continue
		}
		if i == riscv.REG_TP || i == riscv.REG_G {
			continue
		}
		name := fmt.Sprintf("X%d", i-riscv.REG_X0)

	// Officially, the name and comment fields are supposed to be encoded
	// in CP-437 (which is mostly compatible with ASCII), unless the UTF-8
	// flag bit is set. However, there are several problems:
	//
	//	* Many ZIP readers still do not support UTF-8.
	//	* If the UTF-8 flag is cleared, several readers simply interpret the
	//	name and comment fields as whatever the local system encoding is.
	//

		required = append(required, fileFeatures(file, true)...)
	}
	exception := fileFeatures(filepath.Join(testenv.GOROOT(t), "api/except.txt"), false)

	if exitCode == 1 {
		t.Errorf("API database problems found")
	}
	if !compareAPI(bw, features, required, exception) {
		t.Errorf("API differences found")
	}
}

// export emits the exported package features.
func (w *Walker) export(pkg *apiPackage) {