ubuntu-buildroot/output/build/host-gcc-initial-11.4.0/gcc/jit/notes.txt

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Client Code . Generated . libgccjit.so
. code .
. . JIT API . JIT "Frontend". (libbackend.a)
....................................................................................
│ . . . .
──────────────────────────> . .
. . │ . .
. . V . .
. . ──> libgccjit.c .
. . │ (error-checking).
. . │ .
. . ──> jit-recording.c
. . (record API calls)
. . <─────── .
. . │ . .
<─────────────────────────── . .
│ . . . .
│ . . . .
V . . gcc_jit_context_compile .
──────────────────────────> . .
. . │ start of recording::context::compile ()
. . │ . .
. . │ start of playback::context::compile ()
. . │ (create tempdir) .
. . │ . .
. . │ ACQUIRE MUTEX .
. . │ . .
. . V───────────────────────> toplev::main (for now)
. . . . │
. . . . (various code)
. . . . │
. . . . V
. . . <───────────────── langhook:parse_file
. . . │ .
. . . │ (jit_langhook_parse_file)
. . . │ .
..........................................│..................VVVVVVVVVVVVV...
. . . │ . No GC in here
. . . │ jit-playback.c
. . . │ (playback of API calls)
. . . ───────────────> creation of functions,
. . . . types, expression trees
. . . <──────────────── etc
. . . │(handle_locations: add locations to
. . . │ linemap and associate them with trees)
. . . │ .
. . . │ . No GC in here
..........................................│..................AAAAAAAAAAAAA...
. . . │ for each function
. . . ──> postprocess
. . . │ .
. . . ────────────> cgraph_finalize_function
. . . <────────────
. . . <── .
. . . │ .
. . . ──────────────────> (end of
. . . . │ langhook_parse_file)
. . . . │
. . . . (various code)
. . . . │
. . . . ↓
. . . <───────────────── langhook:write_globals
. . . │ .
. . . │ (jit_langhook_write_globals)
. . . │ .
. . . │ .
. . . ──────────────────> finalize_compilation_unit
. . . . │
. . . . (the middle─end and backend)
. . . . ↓
. . <───────────────────────────── end of toplev::main
. . │ . .
. . V───────────────────────> toplev::finalize
. . . . │ (purge internal state)
. . <──────────────────────── end of toplev::finalize
. . │ . .
. . V─> playback::context::postprocess:
. . │ . .
. . │ (assuming an in-memory compile):
. . │ . .
. . --> Convert assembler to DSO, via embedded
. . copy of driver:
. . driver::main ()
. . invocation of "as"
. . invocation of "ld"
. . driver::finalize ()
. . <----
. . │ . .
. . │ . Load DSO (dlopen "fake.so")
. . │ . .
. . │ . Bundle it up in a jit::result
. . <── . .
. . │ . .
. . │ RELEASE MUTEX .
. . │ . .
. . │ end of playback::context::compile ()
. . │ . .
. . │ playback::context dtor
. . ──> . .
. . │ Normally we cleanup the tempdir here:
. . │ ("fake.so" is unlinked from the
. . │ filesystem at this point)
. . │ If the client code requested debuginfo, the
. . │ cleanup happens later (in gcc_jit_result_release)
. . │ to make it easier on the debugger (see PR jit/64206)
. . <── . .
. . │ . .
. . │ end of recording::context::compile ()
<─────────────────────────── . .
│ . . . .
V . . gcc_jit_result_get_code .
──────────────────────────> . .
. . │ dlsym () within loaded DSO
<─────────────────────────── . .
Get (void*). . . .
│ . . . .
│ Call it . . . .
───────────────> . . .
. │ . . .
. │ . . .
<─────────────── . . .
│ . . . .
etc│ . . . .
│ . . . .
V . . gcc_jit_result_release .
──────────────────────────> . .
. . │ dlclose () the loaded DSO
. . │ (code becomes uncallable)
. . │ . .
. . │ If the client code requested debuginfo, then
. . │ cleanup of the tempdir was delayed.
. . │ If that was the case, clean it up now.
<─────────────────────────── . .
│ . . . .