nx_dwarf_cfi.nx

nx_dwarf_cfi.nx -- DWARF .debug_frame / .eh_frame builder. Encodes Call Frame Information used by stack unwinders (debuggers, exception handlers, profilers, perf). Today our riscv.nx emits .cfi_* DIRECTIVES for the gcc-as path; this module produces the BINARY section directly so the off-C path doesn't need gcc-as. CFI section structure (DWARF v5 §6.4): Common Information Entry (CIE) -- shared header for many FDEs: length u32 bytes after this field CIE_id u32 = 0xFFFFFFFF for .debug_frame, 0 for .eh_frame version u8 = 1 augstr NUL-term ASCII augmentation code_align uleb128 multiplier for advance_loc data_align sleb128 multiplier for cfa_offset ra_reg uleb128 return-address register (typically 1=ra) init_insns ... DW_CFA_* opcodes for default state Frame Description Entry (FDE) per function: length u32 CIE_ptr u32 offset back to the CIE (.debug_frame) / relative offset (.eh_frame) init_loc u64 function start address (RV64) range u64 function size insns ... DW_CFA_* opcodes describing per-PC state What we ship today (v0.0.1): * CIE writer (begin/end + opcode emit) * FDE writer (begin/end + opcode emit) * DW_CFA_* opcode constants * advance_loc / def_cfa_offset / offset(reg, off) helpers Pairs with riscv.nx's .cfi directive emission: same logical information, different encoding (binary vs assembler-text). When the off-C path is the only path, riscv.nx will swap to emitting straight to nx_dwarf_cfi instead of textual directives.