[2pt] Enrich symtab when the new function's prototype is allocated

Product: Tarantool
Since: 2.10
Root document: https://www.tarantool.io/en/doc/latest/book/app_server/luajit_memprof/
Dev issue: https://github.com/tarantool/tarantool/issues/5815
SME: @ igormunkin , @ Buristan

Details

If one runs this test chunk named <tests.lua>:

1  jit.off()
2
3  local ffi = require 'ffi'
4
5  local binfile = "/tmp/memprof_"..(arg[0]):match("([^/]*).lua")..".bin"
6
7  local st, err = misc.memprof.start(binfile)
8  assert(st, err)
9
10 local chunk = [[
11 local t = {
12   string.rep("x", 11111), 42, nil
13 }
14
15 function lua_global_f()
16   local str = string.rep("1", 1024 * 1024)
17 end
18 ]]
19
20 local f, err = loadstring(chunk)
21 assert(f, err)
22 f()
23 lua_global_f()
24
25 collectgarbage()
26
27 local st, err = misc.memprof.stop()
28 assert(st, err)

by Tarantool:

$ tarantool tests.lua

and runs the profiler parser, the output is the following:

$ tarantool -e 'require("memprof")(arg[1])' - /tmp/memprof_tests.bin
ALLOCATIONS
@tests.lua:0, line 20: 17	1736	0
@builtin/strict.lua:14, line 15: 3	458	0
CFUNC 0x401747a0: 1	1048593	0  --<-- lua_global_f()
CFUNC 0x41ea1e18: 1	11128	0  --<-- f()
CFUNC 0x41ea1e18: 1	20	0
CFUNC 0x41ea1e18: 1	72	0
...

This happens because the prototype of the lua_global_f() and f() functions does not exist when the profiler starts.
To report allocations from the new functions, the allocation events should be enriched with the info about new prototypes.

Start by running the tests.lua chunk and the memprof parser command shown in the issue to reproduce the missing prototype information for lua_global_f() and f(). Trace how allocation events are enriched when new functions are loaded. Done means allocations from those functions are reported with their prototype information rather than only as unresolved CFUNC entries.