NationalSecurityAgency/ghidra · error · IllegalArgumentException

Sleigh language required

Error message

Sleigh language required

What it means

Thrown by the DebuggerEmulateFunctionDialog constructor when the selected Function's program is not backed by a SleighLanguage. SleighLanguage is Ghidra's p-code processor specification; the emulator and the dialog's VarStorage/executor machinery all depend on it. Non-Sleigh Language implementations (legacy or custom) cannot drive p-code emulation, so the dialog refuses to open.

Source

Thrown at Ghidra/Debug/Debugger/src/main/java/ghidra/app/plugin/core/debug/gui/emulation/DebuggerEmulateFunctionDialog.java:202

		@Override
		public ActionContext getActionContext(MouseEvent e) {
			return new OutputActionContext(outputsFilterPanel.getSelectedItems());
		}
	};

	protected final DomainObjectListener listenerForFunction = new DomainObjectListenerBuilder(this)
			.any(DomainObjectEvent.RESTORED)
			.terminate(inputActions::contextChanged)
			.with(FunctionChangeRecord.class)
			.each(ProgramEvent.FUNCTION_CHANGED)
			.call(this::functionChanged)
			.build();

	public DebuggerEmulateFunctionDialog(PluginTool tool, Function function) {
		super("Emulate %s of %s".formatted(function.getName(), function.getProgram().getName()),
			false, true, true, true);
		if (!(function.getProgram().getLanguage() instanceof SleighLanguage language)) {
			throw new IllegalArgumentException("Sleigh language required");
		}
		this.tool = tool;
		this.function = function;
		this.language = language;

		inputsTableModel = new InputsTableModel(tool, this);
		outputsTableModel = new OutputsTableModel(tool, this);

		inputsTableModel.addTableModelListener(evt -> {
			inputActions.contextChanged();
		});
		outputsTableModel.addTableModelListener(evt -> {
			outputActions.contextChanged();
		});

		sentinel = language.getDefaultSpace().getAddress(0xdeadbeef);
		snapshotPeriod = 1;
		nextAlloc = language.getDefaultDataSpace().getAddress(0x7beef000);

View on GitHub (pinned to d5f144c24d)

Solutions

1. Re-import the program with a current Sleigh-based processor specification (.pspec/.sleigh) so its Language is a SleighLanguage.
2. Verify via function.getProgram().getLanguage() instanceof SleighLanguage before launching the emulation dialog, and warn the user instead of constructing it.
3. If working with a custom processor, ensure its Language implementation extends SleighLanguage.
4. Skip the Emulate Function action for programs known to use non-Sleigh languages.

Example fix

// before
new DebuggerEmulateFunctionDialog(tool, function); // throws if non-Sleigh

// after
if (function.getProgram().getLanguage() instanceof SleighLanguage) {
    new DebuggerEmulateFunctionDialog(tool, function);
} else {
    Msg.showWarn(this, null, "Cannot Emulate",
        "Emulation requires a program using a Sleigh language.");
}

boolean canEmulate = function.getProgram().getLanguage() instanceof SleighLanguage;

static boolean isSleigh(Function f) {
    return f.getProgram().getLanguage() instanceof SleighLanguage;
}

try {
    new DebuggerEmulateFunctionDialog(tool, function);
} catch (IllegalArgumentException e) {
    if (e.getMessage().contains("Sleigh language")) {
        Msg.showWarn(this, null, "Cannot Emulate", e.getMessage());
    } else throw e;
}

When it happens

Trigger: Invoking the 'Emulate Function' action/dialog on a Function whose Program was imported or synthesized with a Language that is not an instance of ghidra.app.plugin.processors.sleigh.SleighLanguage.

Common situations: Loading a program built on an obsolete/legacy processor module that predates Sleigh; using a hand-rolled or stub Language implementation in tests; opening emulation on a synthetic DomainObject whose language was set programmatically to a non-Sleigh subclass.

Related errors

• Emulation requires a Sleigh language
• Cannot emulate a trace unless it's opened in the tool.
• Cannot create register container
• TracePlatform must use a Sleigh language
• Trace must use a sleigh-based language

AI-assisted analysis of NationalSecurityAgency/ghidra@d5f144c24d (2026-08-14). Data as JSON: /api/errors/da3f8e2b0da6a06a. Report an issue: GitHub.