Some statements (assignment?) have no line representation in debug.pc2line_buf table and don't work with find_line_num #458
Description
I've been using find_line_num to get line numbers from opcodes. I noticed that certain lines don't have the correct line number in the table.
For example, given this snippet:
let str1 = 'my string';
let str2 = 'another str';
let str3 = '3 string';
let str4 = str1 + str2 + str3;
The opcodes (from js_dump_function_bytecode) are:
opcodes:
push_this
if_false8 4
return_undef
4: push_atom_value "my string"
put_var_ref0 0: str1
push_atom_value "another str"
put_var_ref1 1: str2
push_atom_value "3 string"
put_var_ref2 2: str3
get_var_ref_check 0: str1
get_var_ref_check 1: str2
add
get_var_ref_check 2: str3
add
put_var_ref3 3: str4
undefined
return_async
And the PC to Line output (from 'dump_pc2line') is:
PC LINE COL
- 1 1
22 4 12 <-- no 2 or 3
25 4 19
28 4 17
29 4 26
32 4 24
No line 2 or 3.
But if the snippet is altered to do more than simple assignment like so:
let str1 = 'my' + 'string';
let str2 = 'another' + 'str';
let str3 = '3' + 'string';
let str4 = str1 + str2 + str3;
The opcodes are:
opcodes:
push_this
if_false8 4
return_undef
4: push_atom_value my
push_atom_value string
add
put_var_ref0 0: str1
push_atom_value another
push_atom_value str
add
put_var_ref1 1: str2
push_const8 0: "3"
push_atom_value string
add
put_var_ref2 2: str3
get_var_ref_check 0: str1
get_var_ref_check 1: str2
add
get_var_ref_check 2: str3
add
put_var_ref3 3: str4
undefined
return_async
The PC to Line output is:
PC LINE COL
- 1 1
14 1 17
26 2 22 <-- line 2 and 3 are back
35 3 16
37 4 12
40 4 19
43 4 17
44 4 26
47 4 24
This is problematic for our custom debugging solution.
I haven't verified the bisect, but it worked in the 2024-01-13 release and I suspect it was changed with this commit that added column support.