What causes "empty OP stack" in go-delve/delve?

Inspect the DWARF attribute that produced the instruction bytes (objdump --dwarf=info) for emptiness or truncation

empty OP stack

Error message

empty OP stack

What it means

A non-sentinel error created in ExecuteStackProgram when the DWARF expression finished without leaving any value on the stack, so there is no result to return. The function needs at least one final stack value to produce an address or confirm a piece list.

Source

Thrown at pkg/dwarf/op/op.go:101

		if !ok {
			return 0, nil, fmt.Errorf("invalid instruction %#v", opcode)
		}

		err = fn(opcode, ctxt)
		if err != nil {
			return 0, nil, err
		}
	}

	if ctxt.pieces != nil {
		if len(ctxt.pieces) == 1 && ctxt.pieces[0].Kind == RegPiece {
			return int64(regs.Uint64Val(ctxt.pieces[0].Val)), ctxt.pieces, nil
		}
		return 0, ctxt.pieces, nil
	}

	if len(ctxt.stack) == 0 {
		return 0, nil, errors.New("empty OP stack")
	}

	return ctxt.stack[len(ctxt.stack)-1], nil, nil
}

// PrettyPrint prints the DWARF stack program instructions to `out`.
func PrettyPrint(out io.Writer, instructions []byte, regnumToName func(uint64) string) {
	in := bytes.NewBuffer(instructions)

	for {
		opcode, err := in.ReadByte()
		if err != nil {
			break
		}
		op := Opcode(opcode)
		if name, hasname := opcodeName[op]; hasname {
			io.WriteString(out, name)
			if regnumToName != nil {

View on GitHub (pinned to a23773e6c3)

Solutions

Inspect the DWARF attribute that produced the instruction bytes (objdump --dwarf=info) for emptiness or truncation
Recompile the binary to regenerate correct debug info
Guard the call site: treat an empty-result error as 'no location available' rather than retrying

Defensive patterns

Strategy: try-catch

Validate before calling

if len(instr) == 0 { return errors.New("no location expression") }

Try / catch

_, _, err := op.ExecuteStackProgram(...)
if err != nil && strings.Contains(err.Error(), "empty OP stack") { /* no result value */ }

Prevention

Check that the DWARF attribute is non-empty before executing
Prefer higher-level variable evaluation APIs that handle empty locations

When it happens

Trigger: op.ExecuteStackProgram executed an expression whose opcode stream consumed all stack values (e.g. ends with drop-like operations) or is effectively empty, leaving len(ctxt.stack)==0 at the end.

Common situations: Empty or truncated location attribute bytes in DWARF entries, expression streams mis-parsed due to wrong offset, or expressions designed for composite location results that the evaluator path does not expect.

Related errors

AI-assisted analysis of go-delve/delve@a23773e6c3 (2026-08-31). Data as JSON: /api/errors/aa6031be5af02bbb. Report an issue: GitHub.