1 files changed, 234 insertions, 0 deletions

diff --git a/src/host/genlibbc.lua b/src/host/genlibbc.lua
new file mode 100644
index 00000000..3eb1b827
--- /dev/null
+++ b/src/host/genlibbc.lua
@@ -0,0 +1,234 @@
+----------------------------------------------------------------------------
+-- Lua script to dump the bytecode of the library functions written in Lua.
+-- The resulting 'buildvm_libbc.h' is used for the build process of LuaJIT.
+----------------------------------------------------------------------------
+-- Copyright (C) 2005-2026 Mike Pall. All rights reserved.
+-- Released under the MIT license. See Copyright Notice in luajit.h
+----------------------------------------------------------------------------
+
+local ffi = require("ffi")
+local bit = require("bit")
+local vmdef = require("jit.vmdef")
+local bcnames = vmdef.bcnames
+
+local format = string.format
+
+local isbe = (string.byte(string.dump(function() end), 5) % 2 == 1)
+
+local function usage(arg)
+  io.stderr:write("Usage: ", arg and arg[0] or "genlibbc",
+                  " [-o buildvm_libbc.h] lib_*.c\n")
+  os.exit(1)
+end
+
+local function parse_arg(arg)
+  local outfile = "-"
+  if not (arg and arg[1]) then
+    usage(arg)
+  end
+  if arg[1] == "-o" then
+    outfile = arg[2]
+    if not outfile then usage(arg) end
+    table.remove(arg, 1)
+    table.remove(arg, 1)
+  end
+  return outfile
+end
+
+local function read_files(names)
+  local src = ""
+  for _,name in ipairs(names) do
+    local fp = assert(io.open(name))
+    src = src .. fp:read("*a")
+    fp:close()
+  end
+  return src
+end
+
+local function transform_lua(code)
+  local fixup = {}
+  local n = -30000
+  code = string.gsub(code, "CHECK_(%w*)%((.-)%)", function(tp, var)
+    n = n + 1
+    fixup[n] = { "CHECK", tp }
+    return format("%s=%d", var, n)
+  end)
+  code = string.gsub(code, "PAIRS%((.-)%)", function(var)
+    fixup.PAIRS = true
+    return format("nil, %s, 0x4dp80", var)
+  end)
+  return "return "..code, fixup
+end
+
+local function read_uleb128(p)
+  local v = p[0]; p = p + 1
+  if v >= 128 then
+    local sh = 7; v = v - 128
+    repeat
+      local r = p[0]
+      v = v + bit.lshift(bit.band(r, 127), sh)
+      sh = sh + 7
+      p = p + 1
+    until r < 128
+  end
+  return p, v
+end
+
+-- ORDER LJ_T
+local name2itype = {
+  str = 5, func = 9, tab = 12, int = 14, num = 15
+}
+
+local BC, BCN = {}, {}
+for i=0,#bcnames/6-1 do
+  local name = bcnames:sub(i*6+1, i*6+6):gsub(" ", "")
+  BC[name] = i
+  BCN[i] = name
+end
+local xop, xra = isbe and 3 or 0, isbe and 2 or 1
+local xrc, xrb = isbe and 1 or 2, isbe and 0 or 3
+
+local function fixup_dump(dump, fixup)
+  local buf = ffi.new("uint8_t[?]", #dump+1, dump)
+  local p = buf+5
+  local n, sizebc
+  p, n = read_uleb128(p)
+  local start = p
+  p = p + 4
+  p = read_uleb128(p)
+  p = read_uleb128(p)
+  p, sizebc = read_uleb128(p)
+  local startbc = tonumber(p - start)
+  local rawtab = {}
+  for i=0,sizebc-1 do
+    local op = p[xop]
+    if op == BC.KSHORT then
+      local rd = p[xrc] + 256*p[xrb]
+      rd = bit.arshift(bit.lshift(rd, 16), 16)
+      local f = fixup[rd]
+      if f then
+        if f[1] == "CHECK" then
+          local tp = f[2]
+          if tp == "tab" then rawtab[p[xra]] = true end
+          p[xop] = tp == "num" and BC.ISNUM or BC.ISTYPE
+          p[xrb] = 0
+          p[xrc] = name2itype[tp]
+        else
+          error("unhandled fixup type: "..f[1])
+        end
+      end
+    elseif op == BC.TGETV then
+      if rawtab[p[xrb]] then
+        p[xop] = BC.TGETR
+      end
+    elseif op == BC.TSETV then
+      if rawtab[p[xrb]] then
+        p[xop] = BC.TSETR
+      end
+    elseif op == BC.ITERC then
+      if fixup.PAIRS then
+        p[xop] = BC.ITERN
+      end
+    end
+    p = p + 4
+  end
+  local ndump = ffi.string(start, n)
+  -- Fixup hi-part of 0x4dp80 to LJ_KEYINDEX.
+  ndump = ndump:gsub("\x80\x80\xcd\xaa\x04", "\xff\xff\xf9\xff\x0f")
+  return { dump = ndump, startbc = startbc, sizebc = sizebc }
+end
+
+local function find_defs(src, mode)
+  local defs = {}
+  for name, code in string.gmatch(src, "LJLIB_LUA%(([^)]*)%)%s*/%*(.-)%*/") do
+    local tcode, fixup = transform_lua(code)
+    local func = assert(load(tcode, "", mode))
+    defs[name] = fixup_dump(string.dump(func, mode), fixup)
+    defs[#defs+1] = name
+  end
+  return defs
+end
+
+local function gen_header(defs32, defs64)
+  local t = {}
+  local function w(x) t[#t+1] = x end
+  w("/* This is a generated file. DO NOT EDIT! */\n\n")
+  w("static const int libbc_endian = ") w(isbe and 1 or 0) w(";\n\n")
+  for j,defs in ipairs{defs64, defs32} do
+    local s, sb = "", ""
+    for i,name in ipairs(defs) do
+      local d = defs[name]
+      s = s .. d.dump
+      sb = sb .. string.char(i) .. ("\0"):rep(d.startbc - 1)
+              .. (isbe and "\0\0\0\255" or "\255\0\0\0"):rep(d.sizebc)
+              .. ("\0"):rep(#d.dump - d.startbc - d.sizebc*4)
+    end
+    if j == 1 then
+      w("static const uint8_t libbc_code[] = {\n#if LJ_FR2\n")
+    else
+      w("\n#else\n")
+    end
+    local n = 0
+    for i=1,#s do
+      local x = string.byte(s, i)
+      local xb = string.byte(sb, i)
+      if xb == 255 then
+        local name = BCN[x]
+        local m = #name + 4
+        if n + m > 78 then n = 0; w("\n") end
+        n = n + m
+        w("BC_"); w(name)
+      else
+        local m = x < 10 and 2 or (x < 100 and 3 or 4)
+        if xb == 0 then
+          if n + m > 78 then n = 0; w("\n") end
+        else
+          local name = defs[xb]:gsub("_", ".")
+          if n ~= 0 then w("\n") end
+          w("/* "); w(name); w(" */ ")
+          n = #name + 7
+        end
+        n = n + m
+        w(x)
+      end
+      w(",")
+    end
+  end
+  w("\n#endif\n0\n};\n\n")
+  w("static const struct { const char *name; int ofs; } libbc_map[] = {\n")
+  local m32, m64 = 0, 0
+  for i,name in ipairs(defs32) do
+    assert(name == defs64[i])
+    w('{"'); w(name); w('",'); w(m32) w('},\n')
+    m32 = m32 + #defs32[name].dump
+    m64 = m64 + #defs64[name].dump
+    assert(m32 == m64)
+  end
+  w("{NULL,"); w(m32); w("}\n};\n\n")
+  return table.concat(t)
+end
+
+local function write_file(name, data)
+  if name == "-" then
+    assert(io.write(data))
+    assert(io.flush())
+  else
+    local fp = io.open(name)
+    if fp then
+      local old = fp:read("*a")
+      fp:close()
+      if data == old then return end
+    end
+    fp = assert(io.open(name, "w"))
+    assert(fp:write(data))
+    assert(fp:close())
+  end
+end
+
+local outfile = parse_arg(arg)
+local src = read_files(arg)
+local defs32 = find_defs(src, "Wdts")
+local defs64 = find_defs(src, "Xdts")
+local hdr = gen_header(defs32, defs64)
+write_file(outfile, hdr)
+