mirror of
https://github.com/Druthulu/BFM-decomp
synced 2026-10-01 15:43:06 -04:00
Drew T
ce7780b91f
Item 1's remaining half. Oracle mechanized and reusable at tools/oracle/reg_renumber_swap.sh: break at reload entry (cc1 unstripped: reg_renumber @0x82d4330, reload @0x815d4d7), swap two hard regs across reg_renumber, finish the compile, re-score with masked_diff REUSED not reimplemented (R33). NEGATIVE CONTROL: a no-op swap (31<->31) reproduces exactly the baseline 13 mismatches, so the harness faithfully reproduces the pinned compile. RESULT: both contested swaps are far WORSE — <-> (17 pseudos) = 345 mismatches +1 insn; <-> (31 pseudos) = 97. Baseline 13. WHY, AND IT REFUTES THE FRAMING: reading .greg for cluster B's own insn shows (set (reg/v:SI 6 a2) (plus:SI (reg/v:SI 5 a1) (const_int 60))) — the destination is a HARD register, not a pseudo. reg_renumber only maps pseudos (>= FIRST_PSEUDO_REGISTER = 68), so that value is structurally unreachable by this oracle. The draft has NO register __asm__ pins (header says so, grep confirms), so is hard because it is an incoming PARAMETER register that local-alloc reused as a destination. VERDICT for func_80176734 (51,198 ins): the residual is NOT global-allocation 2-colouring. It is the LOCAL-alloc hard-reg reuse / tying class — combine_regs (2.7.2 local-alloc.c:1722) + qty_phys_copy_sugg, i.e. regalloc.md K8/RC-4, whose lever is C-level LIFETIME SHAPING, not the permuter and not reg_renumber. That also explains the flat permuter: it was mutating a dial that does not control this residual. MAP REFINEMENT OWED: §H presents the swap oracle as THE way to discriminate RC-6 from S3 in one gdb run. It has an unstated PRECONDITION — the contested registers must be held by PSEUDOS. Check .greg first; if they appear as (reg/v:SI N ...) with N < 68 they are already hard, and a coarse swap returns a large meaningless number (345 here) that looks like a verdict and is not one. Tree clean; nothing banked, nothing broken.
75 lines
2.8 KiB
Bash
75 lines
2.8 KiB
Bash
#!/bin/bash
|
|
# swap_oracle.sh — the regalloc.md §H reg_renumber-swap oracle, mechanized.
|
|
#
|
|
# QUESTION IT ANSWERS: when a residual is "register identity AND an instruction reordering", you
|
|
# cannot tell from the diff whether the reorder is a SCHEDULING decision (S3 — C often cannot move
|
|
# it) or merely a CONSEQUENCE of the register grant (fix the regs and the schedule follows).
|
|
#
|
|
# METHOD: break at `reload` entry, swap two hard registers throughout `reg_renumber` (so every
|
|
# pseudo allocated to A gets B and vice versa), let compilation finish, and re-score the result with
|
|
# the SAME comparison match_one uses (masked_diff, reused not reimplemented — R33).
|
|
#
|
|
# diff count DROPS -> the residual is ALLOCATION; route to density/lifetime levers.
|
|
# diff count STAYS -> the reorder is not a consequence of these two registers.
|
|
#
|
|
# usage: swap_oracle.sh <hardA> <hardB> (MIPS: v0=2 v1=3 a0=4 a1=5 a2=6 a3=7)
|
|
set -u
|
|
REPO=/home/musashi/bfm-decomp
|
|
D=$REPO/.run/giants/fable_cd4/dumps_o734
|
|
A=$1; B=$2
|
|
cd "$D" || exit 1
|
|
|
|
cat > swap_${A}_${B}.gdb <<EOF
|
|
set pagination off
|
|
set confirm off
|
|
set height 0
|
|
set debuginfod enabled off
|
|
break *0x815d4d7
|
|
commands 1
|
|
silent
|
|
set \$rr = *(long *)0x082d4330
|
|
set \$mx = *(long *)0x082d3a10
|
|
set \$i = 0
|
|
set \$n = 0
|
|
while \$i < \$mx
|
|
set \$h = *(short *)(\$rr + \$i*2)
|
|
if \$h == $A
|
|
set *(short *)(\$rr + \$i*2) = $B
|
|
set \$n = \$n + 1
|
|
else
|
|
if \$h == $B
|
|
set *(short *)(\$rr + \$i*2) = $A
|
|
set \$n = \$n + 1
|
|
end
|
|
end
|
|
set \$i = \$i + 1
|
|
end
|
|
printf "SWAPPED %d pseudo(s) between hard %d and hard %d\n", \$n, $A, $B
|
|
continue
|
|
end
|
|
run -quiet -O2 -G0 -mips1 -mcpu=3000 -mgas -msoft-float -fgnu-linker t.i -o swap_${A}_${B}.s
|
|
quit
|
|
EOF
|
|
|
|
timeout 600 gdb -batch -x swap_${A}_${B}.gdb "$REPO/tools/bin/gcc-2.7.2-psx/cc1" 2>&1 | grep -E "^SWAPPED"
|
|
[ -s swap_${A}_${B}.s ] || { echo " (no output produced)"; exit 1; }
|
|
|
|
python3 "$REPO/tools/maspsx/maspsx.py" --aspsx-version=2.56 --expand-div < swap_${A}_${B}.s > swap_${A}_${B}.mas.s 2>/dev/null
|
|
# `as` must run from the REPO ROOT: the emitted .s carries a RELATIVE `.include "include/labels.inc"`.
|
|
( cd "$REPO" && mipsel-linux-gnu-as -march=r3000 -mtune=r3000 -no-pad-sections -O1 -G0 -Iinclude \
|
|
-o "$D/swap_${A}_${B}.o" "$D/swap_${A}_${B}.mas.s" ) 2>/dev/null \
|
|
|| { echo " (assemble failed)"; exit 1; }
|
|
|
|
cd "$REPO" && python3 - "$D/swap_${A}_${B}.o" "$A" "$B" <<'PY'
|
|
import sys, os
|
|
sys.path.insert(0, 'tools')
|
|
import masked_diff as M
|
|
obj, A, B = sys.argv[1], sys.argv[2], sys.argv[3]
|
|
tgt = 'asm/ov_SC01_077/nonmatchings/ov_SC01_077_jr_801734BC/func_80176734.s'
|
|
mine = M.insns_from_object(obj, 'func_80176734')
|
|
want = M.insns_from_s(tgt)
|
|
d = M.structured_diff(mine, want)
|
|
print(" swap $%s<->$%s : mine=%d ins, target=%d ins, %d mismatched (baseline 13)"
|
|
% (A, B, len(mine), len(want), len(d)))
|
|
PY
|