javaclass

Change of bytecode.py

6:a714f8355910
bytecode.py
     1.1 --- a/bytecode.py	Fri Oct 29 18:48:35 2004 +0200
     1.2 +++ b/bytecode.py	Sun Nov 07 17:42:07 2004 +0100
     1.3 @@ -8,16 +8,33 @@
     1.4  """
     1.5  
     1.6  import dis # for access to Python bytecode values
     1.7 +from UserDict import UserDict
     1.8  
     1.9  # Bytecode production classes.
    1.10  
    1.11  class BytecodeWriter:
    1.12      def __init__(self):
    1.13          self.loops = []
    1.14 -        self.jumps = []
    1.15 +        self.jumps = {}
    1.16          self.output = []
    1.17          self.position = 0
    1.18  
    1.19 +        # Mapping from values to indexes.
    1.20 +        self.constants = {}
    1.21 +
    1.22 +        # Mapping from names to indexes.
    1.23 +        # NOTE: This may be acquired from elsewhere.
    1.24 +        self.globals = {}
    1.25 +
    1.26 +    def get_output(self):
    1.27 +        output = []
    1.28 +        for element in self.output:
    1.29 +            if isinstance(element, LazyValue):
    1.30 +                output.append(chr(element.value))
    1.31 +            else:
    1.32 +                output.append(chr(element))
    1.33 +        return "".join(output)
    1.34 +
    1.35      # Special methods.
    1.36  
    1.37      def end_loop(self):
    1.38 @@ -26,16 +43,40 @@
    1.39          self.output[current_loop_start + 1] = self.position
    1.40          self.pop_block()
    1.41  
    1.42 -    def jump_to_next(self, status):
    1.43 -        self.jumps.push(self.position)
    1.44 -        if status:
    1.45 +    def jump_to_label(self, status, name):
    1.46 +        # Record the instruction using the jump.
    1.47 +        if not self.jumps.has_key(name):
    1.48 +            self.jumps[name] = []
    1.49 +        self.jumps[name].append(self.position)
    1.50 +        if status is None:
    1.51 +            self.jump_forward()
    1.52 +        elif status:
    1.53              self.jump_if_true()
    1.54          else:
    1.55              self.jump_if_false()
    1.56  
    1.57 -    def start_next(self):
    1.58 -        current_jump_start = self.jumps.pop()
    1.59 -        self.output[current_jump_start + 1] = self.position
    1.60 +    def start_label(self, name):
    1.61 +        # Fill in all jump instructions.
    1.62 +        for jump_instruction in self.jumps[name]:
    1.63 +            self.output[jump_instruction + 1] = self.position
    1.64 +
    1.65 +    # Complicated methods.
    1.66 +
    1.67 +    def load_const(self, value):
    1.68 +        self.output.append(opmap["LOAD_CONST"])
    1.69 +        if not self.constants.has_key(value):
    1.70 +            self.constants[value] = len(self.constants.keys())
    1.71 +        self.output.append(self.constants[value])
    1.72 +
    1.73 +    def load_global(self, name):
    1.74 +        self.output.append(opmap["LOAD_GLOBAL"])
    1.75 +        if not self.globals.has_key(value):
    1.76 +            self.globals[name] = len(self.globals.keys())
    1.77 +        self.output.append(self.globals[name])
    1.78 +
    1.79 +    def load_fast(self, index):
    1.80 +        self.output.append(opmap["LOAD_FAST"])
    1.81 +        self.output.append(index)
    1.82  
    1.83      # Normal bytecode generators.
    1.84  
    1.85 @@ -55,12 +96,57 @@
    1.86          self.output.append(offset) # May be filled in later
    1.87          self.position += 2
    1.88  
    1.89 +    def jump_forward(self, offset=None):
    1.90 +        self.output.append(opmap["JUMP_FORWARD"])
    1.91 +        self.output.append(offset) # May be filled in later
    1.92 +        self.position += 2
    1.93 +
    1.94 +# Utility classes and functions.
    1.95 +
    1.96 +class LazyDict(UserDict):
    1.97 +    def __getitem__(self, key):
    1.98 +        if not self.data.has_key(key):
    1.99 +            self.data[key] = LazyValue()
   1.100 +        return self.data[key]
   1.101 +    def __setitem__(self, key, value):
   1.102 +        if self.data.has_key(key):
   1.103 +            existing_value = self.data[key]
   1.104 +            if isinstance(existing_value, LazyValue):
   1.105 +                existing_value.value = value
   1.106 +                return
   1.107 +        self.data[key] = value
   1.108 +
   1.109 +class LazyValue:
   1.110 +    def __init__(self, value=None):
   1.111 +        self.value = value
   1.112 +
   1.113 +def signed(value, limit):
   1.114 +
   1.115 +    """
   1.116 +    Return the signed integer from the unsigned 'value', where 'limit' (a value
   1.117 +    one greater than the highest possible positive integer) is used to determine
   1.118 +    whether a negative or positive result is produced.
   1.119 +    """
   1.120 +
   1.121 +    d, r = divmod(value, limit)
   1.122 +    if d == 1:
   1.123 +        mask = limit * 2 - 1
   1.124 +        return -1 - (value ^ mask)
   1.125 +    else:
   1.126 +        return value
   1.127 +
   1.128 +def signed2(value):
   1.129 +    return signed(value, 0x8000)
   1.130 +
   1.131 +def signed4(value):
   1.132 +    return signed(value, 0x80000000)
   1.133 +
   1.134  # Bytecode conversion.
   1.135  
   1.136  class BytecodeReader:
   1.137      def __init__(self, class_file):
   1.138          self.class_file = class_file
   1.139 -        self.position_mapping = {}
   1.140 +        self.position_mapping = LazyDict()
   1.141  
   1.142      def process(self, code, program):
   1.143          self.java_position = 0
   1.144 @@ -120,7 +206,8 @@
   1.145          # NOTE: Not using the index to type the list/array.
   1.146          index = arguments[0] << 8 + arguments[1]
   1.147  
   1.148 -        program.build_list()
   1.149 +        program.build_list()        # Stack: count, list
   1.150 +        program.rot_two()           # Stack: list, count
   1.151          program.setup_loop()
   1.152          program.load_global("range")
   1.153          program.load_const(0)       # Stack: list, count, range, 0
   1.154 @@ -315,12 +402,12 @@
   1.155      getstatic = getfield # Ignoring Java restrictions
   1.156  
   1.157      def goto(self, arguments, program):
   1.158 -        offset = arguments[0] << 8 + arguments[1]
   1.159 +        offset = signed2(arguments[0] << 8 + arguments[1])
   1.160          java_absolute = self.java_position + offset
   1.161          program.jump_absolute(self.position_mapping[java_absolute])
   1.162  
   1.163      def goto_w(self, arguments, program):
   1.164 -        offset = arguments[0] << 24 + arguments[1] << 16 + arguments[2] << 8 + arguments[3]
   1.165 +        offset = signed4(arguments[0] << 24 + arguments[1] << 16 + arguments[2] << 8 + arguments[3])
   1.166          java_absolute = self.java_position + offset
   1.167          program.jump_absolute(self.position_mapping[java_absolute])
   1.168  
   1.169 @@ -378,12 +465,12 @@
   1.170      idiv = fdiv
   1.171  
   1.172      def _if_xcmpx(self, arguments, program, op):
   1.173 -        offset = arguments[0] << 8 + arguments[1]
   1.174 +        offset = signed2(arguments[0] << 8 + arguments[1])
   1.175          java_absolute = self.java_position + offset
   1.176          program.compare_op(op)
   1.177 -        program.jump_to_next(0) # skip if false
   1.178 +        program.jump_to_label(0, "next") # skip if false
   1.179          program.goto(offset)
   1.180 -        program.start_next()
   1.181 +        program.start_label("next")
   1.182  
   1.183      def if_acmpeq(self, arguments, program):
   1.184          # NOTE: No type checking performed.
   1.185 @@ -558,14 +645,156 @@
   1.186      isub = fsub
   1.187      iushr = ishr # Ignoring distinctions between arithmetic and logical shifts
   1.188  
   1.189 -    def ishr(self, arguments, program):
   1.190 +    def ixor(self, arguments, program):
   1.191          # NOTE: No type checking performed.
   1.192          program.binary_xor()
   1.193  
   1.194      def jsr(self, arguments, program):
   1.195 -        offset = arguments[0] << 8 + arguments[1]
   1.196 +        offset = signed2(arguments[0] << 8 + arguments[1])
   1.197 +        java_absolute = self.java_position + offset
   1.198 +        # Store the address of the next instruction.
   1.199 +        program.load_const(self.position_mapping[self.java_position + 3])
   1.200 +        program.jump_absolute(self.position_mapping[java_absolute])
   1.201 +
   1.202 +    def jsr_w(self, arguments, program):
   1.203 +        offset = signed4(arguments[0] << 24 + arguments[1] << 16 + arguments[2] << 8 + arguments[3])
   1.204          java_absolute = self.java_position + offset
   1.205 +        # Store the address of the next instruction.
   1.206 +        program.load_const(self.position_mapping[self.java_position + 5])
   1.207 +        program.jump_absolute(self.position_mapping[java_absolute])
   1.208 +
   1.209 +    l2d = i2d
   1.210 +    l2f = i2f
   1.211 +
   1.212 +    def l2i(self, arguments, program):
   1.213 +        pass # Preserving Java semantics
   1.214 +
   1.215 +    ladd = iadd
   1.216 +    laload = iaload
   1.217 +    land = iand
   1.218 +    lastore = iastore
   1.219 +
   1.220 +    def lcmp(self, arguments, program):
   1.221 +        # NOTE: No type checking performed.
   1.222 +        program.dup_topx(2)                 # Stack: value1, value2, value1, value2
   1.223 +        program.compare_op(">")             # Stack: value1, value2, result
   1.224 +        program.jump_to_label(0, "equals")
   1.225 +        # True - produce result and branch.
   1.226 +        program.pop_top()                   # Stack: value1, value2
   1.227 +        program.pop_top()                   # Stack: value1
   1.228 +        program.pop_top()                   # Stack:
   1.229 +        program.load_const(1)               # Stack: 1
   1.230 +        program.jump_to_label(None, "next")
   1.231 +        # False - test equality.
   1.232 +        program.start_label("equals")
   1.233 +        program.pop_top()                   # Stack: value1, value2
   1.234 +        program.dup_topx(2)                 # Stack: value1, value2, value1, value2
   1.235 +        program.compare_op("==")            # Stack: value1, value2, result
   1.236 +        program.jump_to_label(0, "less")
   1.237 +        # True - produce result and branch.
   1.238 +        program.pop_top()                   # Stack: value1, value2
   1.239 +        program.pop_top()                   # Stack: value1
   1.240 +        program.pop_top()                   # Stack:
   1.241 +        program.load_const(0)               # Stack: 0
   1.242 +        program.jump_to_label(None, "next")
   1.243 +        # False - produce result.
   1.244 +        program.start_label("less")
   1.245 +        program.pop_top()                   # Stack: value1, value2
   1.246 +        program.pop_top()                   # Stack: value1
   1.247 +        program.pop_top()                   # Stack:
   1.248 +        program.load_const(-1)              # Stack: -1
   1.249 +        program.start_label("next")
   1.250 +
   1.251 +    lconst_0 = iconst_0
   1.252 +    lconst_1 = iconst_1
   1.253 +
   1.254 +    def ldc(self, arguments, program):
   1.255 +        program.load_const(self.class_file.constants[arguments[0] - 1])
   1.256 +
   1.257 +    def ldc_w(self, arguments, program):
   1.258 +        program.load_const(self.class_file.constants[arguments[0] << 8 + arguments[1] - 1])
   1.259 +
   1.260 +    ldc2_w = ldc_w
   1.261 +    ldiv = idiv
   1.262 +    lload = iload
   1.263 +    lload_0 = iload_0
   1.264 +    lload_1 = iload_1
   1.265 +    lload_2 = iload_2
   1.266 +    lload_3 = iload_3
   1.267 +    lmul = imul
   1.268 +    lneg = ineg
   1.269 +
   1.270 +    def lookupswitch(self, arguments, program):
   1.271 +        # Find the offset to the next 4 byte boundary in the code.
   1.272 +        d, r = divmod(self.java_position, 4)
   1.273 +        to_boundary = (4 - r) % 4
   1.274 +        # Get the pertinent arguments.
   1.275 +        arguments = arguments[to_boundary:]
   1.276 +        default = arguments[0] << 24 + arguments[1] << 16 + arguments[2] << 8 + arguments[3]
   1.277 +        npairs = arguments[4] << 24 + arguments[5] << 16 + arguments[6] << 8 + arguments[7]
   1.278 +        # Process the pairs.
   1.279 +        # NOTE: This is not the most optimal implementation.
   1.280 +        pair_index = 8
   1.281 +        for pair in range(0, npairs):
   1.282 +            match = (arguments[pair_index] << 24 + arguments[pair_index + 1] << 16 +
   1.283 +                arguments[pair_index + 2] << 8 + arguments[pair_index + 3])
   1.284 +            offset = signed4(arguments[pair_index + 4] << 24 + arguments[pair_index + 5] << 16 +
   1.285 +                arguments[pair_index + 6] << 8 + arguments[pair_index + 7])
   1.286 +            # Calculate the branch target.
   1.287 +            java_absolute = self.java_position + offset
   1.288 +            # Generate branching code.
   1.289 +            program.dup_top()                                           # Stack: key, key
   1.290 +            program.load_const(match)                                   # Stack: key, key, match
   1.291 +            program.compare_op("==")                                    # Stack: key, result
   1.292 +            program.jump_to_label(0, "end" + str(pair))
   1.293 +            program.pop_top()                                           # Stack: key
   1.294 +            program.pop_top()                                           # Stack:
   1.295 +            program.jump_absolute(self.position_mapping[java_absolute])
   1.296 +            # Generate the label for the end of the branching code.
   1.297 +            program.start_label("end" + str(pair))
   1.298 +            program.pop_top()                                           # Stack: key
   1.299 +            # Update the index.
   1.300 +            pair_index += 8
   1.301 +        # Generate the default.
   1.302 +        java_absolute = self.java_position + default
   1.303 +        program.jump_absolute(self.position_mapping[java_absolute])
   1.304 +
   1.305 +    lor = ior
   1.306 +    lrem = irem
   1.307 +    lreturn = ireturn
   1.308 +    lshl = ishl
   1.309 +    lshr = ishr
   1.310 +    lstore = istore
   1.311 +    lstore_0 = istore_0
   1.312 +    lstore_1 = istore_1
   1.313 +    lstore_2 = istore_2
   1.314 +    lstore_3 = istore_3
   1.315 +    lsub = isub
   1.316 +    lushr = iushr
   1.317 +    lxor = ixor
   1.318 +
   1.319 +    def monitorenter(self, arguments, program):
   1.320          # NOTE: To be implemented.
   1.321 +        pass
   1.322 +
   1.323 +    def monitorexit(self, arguments, program):
   1.324 +        # NOTE: To be implemented.
   1.325 +        pass
   1.326 +
   1.327 +    def multianewarray(self, arguments, program):
   1.328 +        program.build_list()        # Stack: count1, count2, ..., countN, list
   1.329 +        program.rot_two()           # Stack: count1, count2, ..., list, countN
   1.330 +        program.setup_loop()
   1.331 +        program.load_global("range")
   1.332 +        program.load_const(0)       # Stack: list, count, range, 0
   1.333 +        program.rot_three()         # Stack: list, 0, count, range
   1.334 +        program.rot_three()         # Stack: list, range, 0, count
   1.335 +        program.call_function(2)    # Stack: list, range_list
   1.336 +        program.get_iter()          # Stack: list, iter
   1.337 +        program.for_iter()          # Stack: list, iter, value
   1.338 +        for i in range(0, arguments[2]):
   1.339 +                                                # Stack: 
   1.340 +            self.anewarray(arguments, program)  # Stack: list, iter
   1.341  
   1.342      def wide(self, code, program):
   1.343          # NOTE: To be implemented.