mirror of
https://github.com/Druthulu/BFM-decomp
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Drew T
b6fd3fff28
- main:func_80032A74 (422 ins, closeness 1): the residual is ONE reload-time slot at sp+0x48 (u16 draft = 422/422 code, DIFF 22 frame
rows; s16 draft = DIFF 1 at idx 244 lh vs lhu). Every post-parameter slot producer enumerated from gcc-2.7.2 (reload1.c:658 ghost
alter_reg / caller-save.c:249 area / reload1.c:879 invalid-equiv / reload1.c:3499 spill_stack_slot) and refuted on the bytes: combine's
newi2pat ghosts re-derive a narrow load and the site is lhu (no lb, no double load); a save area without sw/lw needs sched.c:4962
staleness and no register-only insn shares a block with a call; $t0 holds no pseudo; LO mult results retry into GR_REGS. Verdict
PROVED at 1 (pin kept with the verdict; ledger WALL-PROVED).
- NEW mechanism measured: local-alloc.c optimize_reg_copy_2 (tmp = x; tmp op= c; x = tmp) mints a ghost with stale refs, but after
regclass -> GR_REGS, allocated, no slot (P13/P14). 18 isolated reproducers, 0 draft variants; cookbook §501-M; accelerators (12).
- tools/ghost_census.py (new): ghosts in a .lreg dump with their class (ST_REGS => slot). tools/cc1_dumps.sh: prints the .frame line,
ins count, spill lines and the census; the under-counting standalone-(use) grep is gone. SETUP rows (R21).
- tools/backlog.py: load_best kept the EARLIEST record at equal closeness (docstring said latest) — the S84 row never rendered; fixed.
- CURRENT_PHASE.md: S84 log + refreshed 🛑 checkpoint (rows (b)(c)(d) next, then T5). No src/config/carve change; fleet check-all
218/218 rc 0 at the S84 preflight.
56 lines
2.6 KiB
Python
56 lines
2.6 KiB
Python
#!/usr/bin/env python3
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"""ghost_census.py — the frame-residue oracle for gcc-2.7.2 dumps (P32 T4b hand pass, 2026-09-06; cookbook §501-M).
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A GHOST is a pseudo that still carries flow's `reg_n_refs > 0` but has NO occurrence left in the insn stream.
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Reload gives every ghost with `reg_renumber < 0` and no REG_EQUIV an 8-byte `alter_reg` slot (reload1.c:658,
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align -1 = BIGGEST_ALIGNMENT) — the "never-referenced frame slot" residual (§172, §501-M). Whether a ghost
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actually gets the slot depends on WHEN it was minted:
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* minted by combine (the `newi2pat` split paths, combine.c:1887 / 1963) — BEFORE regclass, so regclass sees no
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occurrence and gives it `ST_REGS or none`: unallocatable → slot. [these are the ones that matter]
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* minted by local-alloc's `optimize_reg_copy_2` (`tmp = x; tmp = tmp op c; x = tmp;`) — AFTER regclass, so it
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keeps `GR_REGS` and no conflicts: global allocates it → NO slot. (byte-measured, P14 in
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.run/P32/t4c/func_80032A74/)
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So the census reads the `.lreg` dump (post-sched, pre-alloc: the register headers are flow's counts as updated by
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combine/sched/update_equiv_regs) and reports every header whose pseudo does not occur in the insn stream, with its
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class — `ST_REGS or none` ⇒ this ghost WILL take a slot; `GR_REGS …` ⇒ it will not. Use `vars=` on the `.frame`
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line as the final arbiter (tools/cc1_dumps.sh prints both).
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usage: ghost_census.py <tag>.i.lreg [<tag>.i.lreg ...]
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exit 0 always (a census, not a gate); prints one line per ghost, nothing when there are none.
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"""
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import re
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import sys
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def census(path):
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text = open(path, errors="replace").read()
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first_insn = text.find("\n(")
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headers, body = (text[:first_insn], text[first_insn:]) if first_insn >= 0 else (text, "")
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regs = re.findall(r"^Register (\d+) used (\d+) times[^\n]*?;\s*([^\n]*)$", headers, re.M)
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occurrences = set(re.findall(r"\(reg[^ ]* (\d+)\)", body))
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out = []
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for regno, refs, tail in regs:
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if regno not in occurrences:
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cls = tail.strip().rstrip(".")
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slot = "SLOT" if "ST_REGS" in cls or "NO_REGS" in cls else "allocatable, no slot"
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out.append((int(regno), int(refs), cls, slot))
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return out
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def main(argv):
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if len(argv) < 2 or argv[1] in ("-h", "--help"):
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print(__doc__)
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return 0
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for path in argv[1:]:
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rows = census(path)
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tag = path if len(argv) > 2 else ""
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for regno, refs, cls, slot in rows:
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print(f" GHOST{(' ' + tag) if tag else ''}: pseudo {regno} refs={refs} [{cls}] -> {slot}")
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return 0
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if __name__ == "__main__":
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sys.exit(main(sys.argv))
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