pogo59
commented
4 years ago We should probably print something like "DW_LNS_unknown" instead
We do tolerate these (without erroring) when reading the line-number program. We should print something reasonable in the opcode_lengths table, although I'd want DW_LNS_unknown_NNN or something similar.
Extended Description
If the opcode base of a line table prologue is higher than 13 (i.e. the program defines unknown standard opcodes), the unknown opcodes are printed as "(null)" in the array, which doesn't look great. We should probably print something like "DW_LNS_unknown" instead, which roughly matches what is done for unknown DWAT* and other DWARF constants.
See test/tools/llvm-dwarfdump/X86/debug-line.s for an example:
CHECK-NEXT: opcode_base: 14
CHECK-NEXT: standard_opcode_lengths[DW_LNS_copy] = 0
CHECK-NEXT: standard_opcode_lengths[DW_LNS_advance_pc] = 1
CHECK-NEXT: standard_opcode_lengths[DW_LNS_advance_line] = 1
CHECK-NEXT: standard_opcode_lengths[DW_LNS_set_file] = 1
CHECK-NEXT: standard_opcode_lengths[DW_LNS_set_column] = 1
CHECK-NEXT: standard_opcode_lengths[DW_LNS_negate_stmt] = 0
CHECK-NEXT: standard_opcode_lengths[DW_LNS_set_basic_block] = 0
CHECK-NEXT: standard_opcode_lengths[DW_LNS_const_add_pc] = 0
CHECK-NEXT: standard_opcode_lengths[DW_LNS_fixed_advance_pc] = 1
CHECK-NEXT: standard_opcode_lengths[DW_LNS_set_prologue_end] = 0
CHECK-NEXT: standard_opcode_lengths[DW_LNS_set_epilogue_begin] = 0
CHECK-NEXT: standard_opcode_lengths[DW_LNS_set_isa] = 1
CHECK-NEXT: standard_opcode_lengths[(null)] = 0 BAD
The verbose dumping currently prints these as an empty string, probably for the same reason at a guess.