.loc fileno lineno [column] [options]When emitting DWARF2 line number information,
the .loc directive will add a row to the .debug_line line
number matrix corresponding to the immediately following assembly
instruction. The fileno, lineno, and optional column
arguments will be applied to the .debug_line state machine before
the row is added.
The options are a sequence of the following tokens in any order:
basic_blockbasic_block register in the
.debug_line state machine to true.
prologue_endprologue_end register in the
.debug_line state machine to true.
epilogue_beginepilogue_begin register in the
.debug_line state machine to true.
is_stmt valueis_stmt register in the
.debug_line state machine to value, which must be
either 0 or 1.
isa valueisa register in the .debug_line
state machine to value, which must be an unsigned integer.