name: Build WeirdPerformance 2.4-B1 GC test

on:
  push:
    branches:
      - test/wp24b-gc-safe-sweep
    paths:
      - 'experiments/wp24b-gc/**'
      - '.github/workflows/wp24b-gc.yml'
  workflow_dispatch:

permissions:
  contents: read

jobs:
  build:
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v4
      - uses: mlugg/setup-zig@v2
        with:
          version: '0.17.0-dev.1970+67f39b551'
      - name: Build and ABI-validate x86 DLL
        working-directory: experiments/wp24b-gc
        run: |
          set -euo pipefail
          zig build --fetch
          python3 - <<'PY'
          from pathlib import Path
          matches = list(Path("zig-pkg").glob("zhook-*/src/zhook.zig"))
          if len(matches) != 1:
              raise SystemExit(f"expected one pinned zhook source, found {len(matches)}")
          p = matches[0]
          text = p.read_text(encoding="utf-8")
          old = "var patch: [MAX_STOLEN]u8 = .{0x90} ** MAX_STOLEN;"
          new = "var patch: [MAX_STOLEN]u8 = @splat(0x90);"
          if old not in text:
              raise SystemExit("expected pinned zhook repeat initializer not found")
          p.write_text(text.replace(old, new), encoding="utf-8")
          PY

          zig build -Doptimize=small
          DLL=zig-out/bin/weirdperformance_gc24b1.dll
          test -s "$DLL"
          file "$DLL" | tee BINARY_INFO.txt
          file "$DLL" | grep -q 'PE32.*Intel i386'

          if command -v llvm-objdump >/dev/null 2>&1; then
            llvm-objdump -d --x86-asm-syntax=intel "$DLL" > ABI_DISASM.txt
          else
            objdump -d -M intel "$DLL" > ABI_DISASM.txt
          fi

          python3 - <<'PY'
          import re
          from pathlib import Path

          asm = Path("ABI_DISASM.txt").read_text(encoding="utf-8", errors="replace").lower()

          def require(pattern, label):
              if not re.search(pattern, asm, re.S):
                  raise SystemExit(f"ABI validation failed: {label}")

          # zhook must jump to callbacks compiled with L arriving in ECX.
          m = re.search(r"mov\s+edx,\s*0x6f7340.{0,240}?push\s+0x([0-9a-f]+)", asm, re.S)
          if not m:
              raise SystemExit("ABI validation failed: collector callback address not found")
          cb = m.group(1).lstrip("0") or "0"
          pos = asm.find(cb + ":")
          if pos < 0 or not re.search(r"mov\s+esi,\s*ecx", asm[pos:pos+500]):
              raise SystemExit("ABI validation failed: collector callback does not consume L from ECX")

          m = re.search(r"mov\s+edx,\s*0x6f6ef0.{0,240}?push\s+0x([0-9a-f]+)", asm, re.S)
          if not m:
              raise SystemExit("ABI validation failed: lua_close callback address not found")
          cb = m.group(1).lstrip("0") or "0"
          pos = asm.find(cb + ":")
          if pos < 0 or not re.search(r"mov\s+esi,\s*ecx", asm[pos:pos+400]):
              raise SystemExit("ABI validation failed: lua_close callback does not consume L from ECX")

          # Native helper ABI observed in WoW 5875:
          #   ECX=L, EDX=&list, stack arg=all for 0x6F7210.
          require(
              r"lea\s+edx,\s*\[edi\s*\+\s*0x14\].{0,160}?"
              r"mov\s+eax,\s*0x6f7210.{0,120}?"
              r"mov\s+ecx,\s*esi.{0,120}?"
              r"push\s+0x0.{0,80}?call\s+eax",
              "lua_gc_remove_objects register/stack ABI",
          )

          require(
              r"mov\s+eax,\s*0x6f72f0.{0,120}?"
              r"mov\s+ecx,\s*esi.{0,100}?"
              r"xor\s+edx,\s*edx.{0,80}?call\s+eax",
              "lua_gc_sweep_all_lists fastcall ABI",
          )

          for addr, label in (
              ("6f73e0", "lua_gc_full_collection"),
              ("6f7370", "lua_gc_shrink_memory"),
              ("6f7080", "luaCallUserDataGC"),
          ):
              require(
                  rf"mov\s+eax,\s*0x{addr}.{{0,120}}?mov\s+ecx,\s*esi.{{0,80}}?call\s+eax",
                  f"{label} ECX ABI",
              )

          print("ABI validation: PASS")
          PY

          sha256sum "$DLL" | tee SHA256SUMS.txt
      - uses: actions/upload-artifact@v4
        with:
          name: WeirdPerformance-2.4-B1-GC-Safe-Sweep
          path: |
            experiments/wp24b-gc/zig-out/bin/weirdperformance_gc24b1.dll
            experiments/wp24b-gc/SHA256SUMS.txt
            experiments/wp24b-gc/BINARY_INFO.txt
            experiments/wp24b-gc/ABI_DISASM.txt
            experiments/wp24b-gc/README.md
          if-no-files-found: error