From e20157c6e68472e7c4d82d9ed4c0bb5be029c388 Mon Sep 17 00:00:00 2001
From: Mike Pall <mike>
Date: Fri, 22 Feb 2013 01:40:41 +0100
Subject: Add support for embedding LuaJIT bytecode for builtins.

---
 src/host/buildvm_lib.c   | 51 ++++++++++++++++++++++++++++++++++++
 src/host/buildvm_libbc.h | 12 +++++++++
 src/host/genlibbc.lua    | 68 ++++++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 131 insertions(+)
 create mode 100644 src/host/buildvm_libbc.h
 create mode 100644 src/host/genlibbc.lua

(limited to 'src/host')

diff --git a/src/host/buildvm_lib.c b/src/host/buildvm_lib.c
index 40141dfb..182ab90f 100644
--- a/src/host/buildvm_lib.c
+++ b/src/host/buildvm_lib.c
@@ -6,6 +6,7 @@
 #include "buildvm.h"
 #include "lj_obj.h"
 #include "lj_lib.h"
+#include "buildvm_libbc.h"
 
 /* Context for library definitions. */
 static uint8_t obuf[8192];
@@ -151,6 +152,55 @@ static void libdef_func(BuildCtx *ctx, char *p, int arg)
   regfunc = REGFUNC_OK;
 }
 
+static uint32_t libdef_uleb128(uint8_t **pp)
+{
+  uint8_t *p = *pp;
+  uint32_t v = *p++;
+  if (v >= 0x80) {
+    int sh = 0; v &= 0x7f;
+    do { v |= ((*p & 0x7f) << (sh += 7)); } while (*p++ >= 0x80);
+  }
+  *pp = p;
+  return v;
+}
+
+static void libdef_swapbc(uint8_t *p)
+{
+  uint32_t i, sizebc;
+  p += 4;
+  libdef_uleb128(&p);
+  libdef_uleb128(&p);
+  sizebc = libdef_uleb128(&p);
+  for (i = 0; i < sizebc; i++, p += 4) {
+    uint8_t t = p[0]; p[0] = p[3]; p[3] = t;
+    t = p[1]; p[1] = p[2]; p[2] = t;
+  }
+}
+
+static void libdef_lua(BuildCtx *ctx, char *p, int arg)
+{
+  UNUSED(arg);
+  if (ctx->mode == BUILD_libdef) {
+    int i;
+    for (i = 0; libbc_map[i].name != NULL; i++) {
+      if (!strcmp(libbc_map[i].name, p)) {
+	int ofs = libbc_map[i].ofs;
+	int len = libbc_map[i+1].ofs - ofs;
+	obuf[2]++;  /* Bump hash table size. */
+	*optr++ = LIBINIT_LUA;
+	libdef_name(p, 0);
+	memcpy(optr, libbc_code + ofs, len);
+	if (libbc_endian != LJ_BE)
+	  libdef_swapbc(optr);
+	optr += len;
+	return;
+      }
+    }
+    fprintf(stderr, "Error: missing libbc definition for %s\n", p);
+    exit(1);
+  }
+}
+
 static uint32_t find_rec(char *name)
 {
   char *p = (char *)obuf;
@@ -277,6 +327,7 @@ static const LibDefHandler libdef_handlers[] = {
   { "CF(",	")",		libdef_func,		LIBINIT_CF },
   { "ASM(",	")",		libdef_func,		LIBINIT_ASM },
   { "ASM_(",	")",		libdef_func,		LIBINIT_ASM_ },
+  { "LUA(",	")",		libdef_lua,		0 },
   { "REC(",	")",		libdef_rec,		0 },
   { "PUSH(",	")",		libdef_push,		0 },
   { "SET(",	")",		libdef_set,		0 },
diff --git a/src/host/buildvm_libbc.h b/src/host/buildvm_libbc.h
new file mode 100644
index 00000000..d2d83ea6
--- /dev/null
+++ b/src/host/buildvm_libbc.h
@@ -0,0 +1,12 @@
+/* This is a generated file. DO NOT EDIT! */
+
+static const int libbc_endian = 0;
+
+static const uint8_t libbc_code[] = {
+0
+};
+
+static const struct { const char *name; int ofs; } libbc_map[] = {
+{NULL,0}
+};
+
diff --git a/src/host/genlibbc.lua b/src/host/genlibbc.lua
new file mode 100644
index 00000000..b0dbf17a
--- /dev/null
+++ b/src/host/genlibbc.lua
@@ -0,0 +1,68 @@
+----------------------------------------------------------------------------
+-- 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) 2005-2013 Mike Pall. All rights reserved.
+-- Released under the MIT license. See Copyright Notice in luajit.h
+----------------------------------------------------------------------------
+
+local function usage()
+  io.stderr:write("Usage: ", arg and arg[0] or "genlibbc", " lib_*.c\n")
+  os.exit(1)
+end
+
+local function read_source()
+  if not (arg and arg[1]) then usage() end
+  local src = ""
+  for _,name in ipairs(arg) do
+    local fp = assert(io.open(name))
+    src = src .. fp:read("*a")
+    fp:close()
+  end
+  return src
+end
+
+local function find_defs(src)
+  local defs = {}
+  for name, code in string.gmatch(src, "LJLIB_LUA%(([^)]*)%)%s*/%*(.-)%*/") do
+    local env = {}
+    local func = assert(load("return "..code, "", nil, env))()
+    local d = string.dump(func, true)
+    local ofs = 6
+    while string.byte(d, ofs) > 127 do ofs = ofs + 1 end
+    defs[name] = string.sub(d, ofs+1, -2)
+    defs[#defs+1] = name
+  end
+  return defs
+end
+
+local function write_defs(fp, defs)
+  fp:write("/* This is a generated file. DO NOT EDIT! */\n\n")
+  fp:write("static const int libbc_endian = ",
+	   string.byte(string.dump(function() end), 5) % 2, ";\n\n")
+  local s = ""
+  for _,name in ipairs(defs) do
+    s = s .. defs[name]
+  end
+  fp:write("static const uint8_t libbc_code[] = {\n")
+  local n = 0
+  for i=1,#s do
+    local x = string.byte(s, i)
+    fp:write(x, ",")
+    n = n + (x < 10 and 2 or (x < 100 and 3 or 4))
+    if n >= 75 then n = 0; fp:write("\n") end
+  end
+  fp:write("0\n};\n\n")
+  fp:write("static const struct { const char *name; int ofs; } libbc_map[] = {\n")
+  local m = 0
+  for _,name in ipairs(defs) do
+    fp:write('{"', name, '",', m, '},\n')
+    m = m + #defs[name]
+  end
+  fp:write("{NULL,", m, "}\n};\n\n")
+  fp:flush()
+end
+
+local src = read_source()
+local defs = find_defs(src)
+write_defs(io.stdout, defs)
-- 
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