build.lua

local bit = require("bit")
local ffi = require("ffi")

function get_file_name(file)
    local s = file:match("^.+/(.+)$")
    if s == nil then
        return file
    end

    return s
end

function cc_cmd(input, cflags)
    local output = get_file_name(input)
    local cmd = "clang "..input.." "..cflags.." -c -o bin/"..output..".o 2>&1"
    return io.popen(cmd)
end

function ccdeps_cmd(input, cflags)
    local output = get_file_name(input)
    local cmd = "clang -MMD -MF bin/"..output..".d "..input.." "..cflags.." -E > NUL"
    return os.execute(cmd)
end

function get_filetime(input)
    if ffi.os == "Windows" then
        local f = io.popen("forfiles /m build.lua /c \"cmd /c echo @ftime @fdate\"")
        local str = f:read("*a");
        f:close()
        
        -- trim whitespace
        str = str:match"^%s*(.*)":match"(.-)%s*$"
        return str
    else
       return "0" 
    end
end

local crc_table = ffi.new("uint32_t[256]", {
    0x00000000, 0x77073096, 0xee0e612c, 0x990951ba, 0x076dc419, 0x706af48f, 0xe963a535, 0x9e6495a3,
    0x0edb8832, 0x79dcb8a4, 0xe0d5e91e, 0x97d2d988, 0x09b64c2b, 0x7eb17cbd, 0xe7b82d07, 0x90bf1d91,
    0x1db71064, 0x6ab020f2, 0xf3b97148, 0x84be41de, 0x1adad47d, 0x6ddde4eb, 0xf4d4b551, 0x83d385c7,
    0x136c9856, 0x646ba8c0, 0xfd62f97a, 0x8a65c9ec, 0x14015c4f, 0x63066cd9, 0xfa0f3d63, 0x8d080df5,
    0x3b6e20c8, 0x4c69105e, 0xd56041e4, 0xa2677172, 0x3c03e4d1, 0x4b04d447, 0xd20d85fd, 0xa50ab56b,
    0x35b5a8fa, 0x42b2986c, 0xdbbbc9d6, 0xacbcf940, 0x32d86ce3, 0x45df5c75, 0xdcd60dcf, 0xabd13d59,
    0x26d930ac, 0x51de003a, 0xc8d75180, 0xbfd06116, 0x21b4f4b5, 0x56b3c423, 0xcfba9599, 0xb8bda50f,
    0x2802b89e, 0x5f058808, 0xc60cd9b2, 0xb10be924, 0x2f6f7c87, 0x58684c11, 0xc1611dab, 0xb6662d3d,
    0x76dc4190, 0x01db7106, 0x98d220bc, 0xefd5102a, 0x71b18589, 0x06b6b51f, 0x9fbfe4a5, 0xe8b8d433,
    0x7807c9a2, 0x0f00f934, 0x9609a88e, 0xe10e9818, 0x7f6a0dbb, 0x086d3d2d, 0x91646c97, 0xe6635c01,
    0x6b6b51f4, 0x1c6c6162, 0x856530d8, 0xf262004e, 0x6c0695ed, 0x1b01a57b, 0x8208f4c1, 0xf50fc457,
    0x65b0d9c6, 0x12b7e950, 0x8bbeb8ea, 0xfcb9887c, 0x62dd1ddf, 0x15da2d49, 0x8cd37cf3, 0xfbd44c65,
    0x4db26158, 0x3ab551ce, 0xa3bc0074, 0xd4bb30e2, 0x4adfa541, 0x3dd895d7, 0xa4d1c46d, 0xd3d6f4fb,
    0x4369e96a, 0x346ed9fc, 0xad678846, 0xda60b8d0, 0x44042d73, 0x33031de5, 0xaa0a4c5f, 0xdd0d7cc9,
    0x5005713c, 0x270241aa, 0xbe0b1010, 0xc90c2086, 0x5768b525, 0x206f85b3, 0xb966d409, 0xce61e49f,
    0x5edef90e, 0x29d9c998, 0xb0d09822, 0xc7d7a8b4, 0x59b33d17, 0x2eb40d81, 0xb7bd5c3b, 0xc0ba6cad,
    0xedb88320, 0x9abfb3b6, 0x03b6e20c, 0x74b1d29a, 0xead54739, 0x9dd277af, 0x04db2615, 0x73dc1683,
    0xe3630b12, 0x94643b84, 0x0d6d6a3e, 0x7a6a5aa8, 0xe40ecf0b, 0x9309ff9d, 0x0a00ae27, 0x7d079eb1,
    0xf00f9344, 0x8708a3d2, 0x1e01f268, 0x6906c2fe, 0xf762575d, 0x806567cb, 0x196c3671, 0x6e6b06e7,
    0xfed41b76, 0x89d32be0, 0x10da7a5a, 0x67dd4acc, 0xf9b9df6f, 0x8ebeeff9, 0x17b7be43, 0x60b08ed5,
    0xd6d6a3e8, 0xa1d1937e, 0x38d8c2c4, 0x4fdff252, 0xd1bb67f1, 0xa6bc5767, 0x3fb506dd, 0x48b2364b,
    0xd80d2bda, 0xaf0a1b4c, 0x36034af6, 0x41047a60, 0xdf60efc3, 0xa867df55, 0x316e8eef, 0x4669be79,
    0xcb61b38c, 0xbc66831a, 0x256fd2a0, 0x5268e236, 0xcc0c7795, 0xbb0b4703, 0x220216b9, 0x5505262f,
    0xc5ba3bbe, 0xb2bd0b28, 0x2bb45a92, 0x5cb36a04, 0xc2d7ffa7, 0xb5d0cf31, 0x2cd99e8b, 0x5bdeae1d,
    0x9b64c2b0, 0xec63f226, 0x756aa39c, 0x026d930a, 0x9c0906a9, 0xeb0e363f, 0x72076785, 0x05005713,
    0x95bf4a82, 0xe2b87a14, 0x7bb12bae, 0x0cb61b38, 0x92d28e9b, 0xe5d5be0d, 0x7cdcefb7, 0x0bdbdf21,
    0x86d3d2d4, 0xf1d4e242, 0x68ddb3f8, 0x1fda836e, 0x81be16cd, 0xf6b9265b, 0x6fb077e1, 0x18b74777,
    0x88085ae6, 0xff0f6a70, 0x66063bca, 0x11010b5c, 0x8f659eff, 0xf862ae69, 0x616bffd3, 0x166ccf45,
    0xa00ae278, 0xd70dd2ee, 0x4e048354, 0x3903b3c2, 0xa7672661, 0xd06016f7, 0x4969474d, 0x3e6e77db,
    0xaed16a4a, 0xd9d65adc, 0x40df0b66, 0x37d83bf0, 0xa9bcae53, 0xdebb9ec5, 0x47b2cf7f, 0x30b5ffe9,
    0xbdbdf21c, 0xcabac28a, 0x53b39330, 0x24b4a3a6, 0xbad03605, 0xcdd70693, 0x54de5729, 0x23d967bf,
    0xb3667a2e, 0xc4614ab8, 0x5d681b02, 0x2a6f2b94, 0xb40bbe37, 0xc30c8ea1, 0x5a05df1b, 0x2d02ef8d
})

function hash_file(path)
    local f = io.open(path, "rb")
    if f == nil then
        print("Could not load file: "..path)
        return 0
    end

    local str = f:read("*a")
    f:close()

    -- fnv1a
    local hash = 0xFFFFFFFF
    for i=1,#str do
        local c = string.byte(str, i)
        local d = bit.band(bit.bxor(hash, c), 0xFF)

        hash = bit.bxor(crc_table[d], bit.rshift(hash, 8))
    end

    return tonumber(ffi.cast("uint32_t", hash))
end

function do_match_deps(a, b)
    for k,v in pairs(a) do
        if v ~= b[k] then
            print("Difference! "..v.. " | "..b[k])
            return false
        end
    end

    return true
end

function dump(o)
   if type(o) == 'table' then
      local s = '{ '
      for k,v in pairs(o) do
         if type(k) ~= 'number' then k = '"'..k..'"' end
         s = s .. '['..k..'] = ' .. dump(v) .. ','
      end
      return s .. '} '
   else
      return tostring(o)
   end
end

function add_to_database(old_database, new_database, input, deps)
    local l = new_database[input]
    if (l ~= nil) then
        return new_database[input].changed
    end

    local t = get_filetime(input)

    -- check for changes (if it was around before)
    local changed = false
    local old = old_database[input]
    
    -- default to using the old hash unless the file times change
    local hash = 0
    if old ~= nil then
        -- avoid file hashing by using the filetimes
        if old.last_write ~= t then
            -- hash the new file
            hash = hash_file(input)
            
            if hash ~= old.hash or not do_match_deps(old.deps, deps) then
                print("  Changed! "..input.." "..string.format("%x", hash).." | "..string.format("%x", old.hash))
                changed = true
            end
        else
            hash = old.hash
        end
    else
        print("New file who dis? "..input)
        hash = hash_file(input)
        changed = true
    end

    new_database[input] = { ["hash"] = hash, ["last_write"] = t, ["deps"] = deps, ["changed"] = changed }
    return changed
end

function read_database(database)
    local f = io.open("build.cache", "r")
    if f == nil then
        print("No cache... first time?")
        return
    end

    for line in f:lines() do
        -- filename then a colon, the hash in hex then a list of input files separated by spaces
        last_write, path, hash_str, inputs = line:match("([^|]+)|([^:]+):%s(0x%x+)(.*)")

        hash = tonumber(hash_str)
        deps = {}
        for s in inputs:gmatch("%S+") do
            table.insert(deps, s)
        end

        -- print("Conversion: "..hash_str.." -> "..string.format("%08x", hash))
        database[path] = { ["hash"] = hash, ["last_write"] = t, ["deps"] = deps, ["changed"] = false }
    end

    f:close()
end

function update_deps(old_database, new_database, input)
    local dep_path = "bin/"..get_file_name(input)..".d"
    local f = io.open(dep_path, "rb")
    if (f == nil) then
        print("build warning: could not build dependency file for "..input)
        return true
    end

    local str = f:read("*a")
    out, ins = str:match("([^:]+):([^:]+)")
    -- remove the backslash-newlines
    ins = ins:gsub("\\\r\n", "")
    -- simplify the slashes
    ins = ins:gsub("\\", "/")

    -- we keep track of it just for the sake
    changes = false
    deps = {}

    for s in string.gmatch(ins, "%S+") do
        table.insert(deps, s)

        if (s ~= input) then
            -- print(input.." uses "..s)
            if add_to_database(old_database, new_database, s, {}) then
                changes = true
            end
        end
    end

    if add_to_database(old_database, new_database, input, deps) then
        changes = true
    end

    f:close()
    return changes
end

function ends_with(str, ending)
   return ending == "" or str:sub(-#ending) == ending
end

function expand_paths(files)
    new_files = {}
    for i,f in ipairs(files) do
        if ends_with(f, "/") then
            -- read files in directory
            if ffi.os == "Windows" then
                local command = io.popen("dir /B "..f:gsub("/", "\\"))

                for l in command:lines() do
                    if ends_with(l, ".c") then
                        local path = string.gsub(f..l, "\\", "/")
                        table.insert(new_files, path)
                    end
                end

                command:close()
            else
                local command = io.popen("grep -L "..f.."*")

                for l in command:lines() do
                    if ends_with(l, ".c") then
                        table.insert(new_files, l)
                    end
                end

                command:close()
            end
        else
            table.insert(new_files, f)
        end
    end

    return new_files
end

function compile(files, cflags)
    -- fixup any directory queries
    files = expand_paths(files)

    io.stdout:setvbuf("no")
    print("Step 1: Read cache")

    old_database = {}
    read_database(old_database)

    -- prepass C files for the dependencies & update deps file
    print("Step 2: Get dependencies")

    new_database = {}
    changed_files = {}
    for i,f in ipairs(files) do
        local exit_code = ccdeps_cmd(f, cflags)

        if exit_code == 0 and update_deps(old_database, new_database, f) then
            -- we changed the file so we need to recompile it
            table.insert(changed_files, f)
        end
    end

    -- compile C files
    print("Step 3: Compile files")
    local handles = {}
    for i,f in ipairs(changed_files) do
        handles[i] = cc_cmd(f, cflags)
    end

    local has_errors = false
    for key,handle in pairs(handles) do
        local str = handle:read("*a")
        print("~~ "..changed_files[key].." ~~")
        if str:len() ~= 0 then
            print(str)

            new_database[changed_files[key]] = nil
            has_errors = true
        end

        -- if the compile fails then remove from the database
        handle:close()
    end

    -- write new database
    print("Step 4: Update database")
    database_file = io.open("build.cache", "wb")

    for input,entry in pairs(new_database) do
        local hash_str = string.format("%08x", entry.hash)
        database_file:write(entry.last_write.."|"..input..": 0x"..hash_str.." ")

        for k,v in ipairs(entry.deps) do
            database_file:write(v.." ")
        end

        database_file:write("\n")
    end
    database_file:close()

    -- link together
    if not has_errors then
        if next(changed_files) ~= nil then
            return true
        else
            print("No changes, doesn't need to link")
        end
    end
    
    return false
end

function link(output)
    os.execute("clang bin/*.o -g -o bin/"..output)
end

function lib(output, deps)
    if ffi.os == "Windows" then
        os.execute("lib /nologo /out:"..output.." bin/*.o "..deps)
    else
        os.execute("ar -rcs "..output.." bin/*.o "..deps)
    end
end

-- your based build system stuff goes here
files = {
    "src/tb/",
    "src/tb/codegen/",
    "src/tb/bigint/",
    "src/tb/objects/",
    "src/tb/debug/",
    "src/tb/debug/cv/",
    "src/tb/x64/",
    "src/tb/aarch64/",
    "src/tb/opt/",
}

if ffi.os == "Windows" then
    table.insert(files, "src/tb/system/win32.c")
else
    table.insert(files, "src/tb/system/posix.c")
end

local options = "-g -Wall -Werror -Wno-unused-function "
options = options.."-I include "
options = options.."-I deps/mimalloc/include "
options = options.."-I deps/luajit/src "

if compile(files, options) then
    print("Step 5: Link")
    lib("tildebackend.lib", "deps/mimalloc-static.lib deps/luajit/src/lua51.lib")
end