417 Vfunc Sig 9dfecfa2

vfunc_sig

Overview

vfunc_sig is an alternate virtual-function relocation signature used when func_sig is unavailable or unstable.

Field Context

• Related YAML fields: vfunc_sig, vtable_name, vfunc_index, vfunc_offset (and occasionally vfunc_inst_offset).
• Typical role: anchor to a virtual-call pattern tied to a vtable slot.

Generation Principle

• In this repository, vfunc_sig is typically produced by the skill /generate-signature-for-vfuncoffset.
• The anchor is a virtual-call instruction encoding vtable slot displacement (e.g., indirect call/jump via [reg+imm]).
• Signature growth is forward from the target instruction; default workflow documents vfunc_sig_disp = 0.
• Candidates are validated by uniqueness (find_bytes) and robustness.
• The shortest valid unique pattern is selected.
• Slot-related displacement bytes are intentionally preserved/represented so the signature remains slot-specific.

Usage Method

• In preprocess_func_sig_via_mcp, vfunc_sig is a fallback path used when old YAML has no func_sig.
• Required metadata:
  • vfunc_sig
  • vtable_name
  • and vfunc_index or vfunc_offset
• Flow:
  1. Unique-match vfunc_sig in new binary.
  2. Load/generate target vtable YAML.
  3. Resolve function VA via vtable_entries[vfunc_index].
  4. Query function info and emit function YAML with vfunc metadata.

Downstream Use

• Dist gamedata modules mainly consume vfunc_index (offset metadata), not vfunc_sig directly.
• vfunc_sig is primarily used by analysis/preprocess relocation pipelines.

Practical Notes

• Use when function-head signatures are weak but vtable slot identity is stable.
• Keep vfunc_index / vfunc_offset internally consistent (offset = index * 8 in current 64-bit assumptions).
• Reject non-unique signatures.