LlvmGenerator.py 11.6 KB
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#!/usr/bin/env python
# -*- coding: utf-8 -*-

"""
    OpenGEODE - A tiny SDL Editor for TASTE

    This module generates LLVM IR code from SDL process models, allowing
    generation of a binary application without an intermediate language.
    LLVM also allows for various code verification, analysis, and optimization.

    The design is based on the Ada code generator. Check it for details.

    Copyright (c) 2012-2013 European Space Agency

    Designed and implemented by Maxime Perrotin

    Contact: maxime.perrotin@esa.int
"""

import logging
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from singledispatch import singledispatch
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from llvm import core, passes, ee

import ogAST
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import Helper
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LOG = logging.getLogger(__name__)

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__all__ = ['generate']

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# LLVM Global variable - Initialized when the generator is invoked
LLVM = {
    # The LLVM module, which holds all the IR code.
    'module': None,
    # Dictionary that keeps track of which values are defined in the current
    # scope and what their LLVM representation is.
    'named_values': {},
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    # Dictionary that keeps track of the defined states and its integer
    # constant representation
    'states': {},
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    # The builder used for the current function generation.
    'builder': None,
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    # The function optimization passes manager.
    'pass_manager': None,
    # The LLVM execution engine.
    'executor': None
}



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@singledispatch
def generate(ast):
    ''' Generate the code for an item of the AST '''
    raise TypeError('[Backend] Unsupported AST construct')
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# Processing of the AST
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@generate.register(ogAST.Process)
def _process(process):
    ''' Generate LLVM IR code (incomplete) '''
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    process_name = str(process.processName)
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    LOG.info('Generating LLVM IR code for process ' + str(process_name))

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    # In case model has nested states, flatten everything
    Helper.flatten(process)

    # Make an maping {input: {state: transition...}} in order to easily
    # generate the lookup tables for the state machine runtime
    mapping = Helper.map_input_state(process)

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    # Initialise LLVM global structure
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    LLVM['module'] = core.Module.new(process_name)
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    LLVM['pass_manager'] = passes.FunctionPassManager.new(LLVM['module'])
    LLVM['executor'] = ee.ExecutionEngine.new(LLVM['module'])
    # Set up the optimizer pipeline.
    # Start with registering info about how the
    # target lays out data structures.
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#   LLVM['pass_manager'].add(LLVM['executor'].target_data)
#   # Do simple "peephole" optimizations and bit-twiddling optzns.
#   LLVM['pass_manager'].add(passes.PASS_INSTRUCTION_COMBINING)
#   # Reassociate expressions.
#   LLVM['pass_manager'].add(passes.PASS_REASSOCIATE)
#   # Eliminate Common SubExpressions.
#   LLVM['pass_manager'].add(passes.PASS_GVN)
#   # Simplify the control flow graph (deleting unreachable blocks, etc).
#   LLVM['pass_manager'].add(passes.PASS_CFG_SIMPLIFICATION)
#   LLVM['pass_manager'].initialize()
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    # Initialize states enum
    for name in process.mapping.iterkeys():
        if not name.endswith('START'):
            cons = core.Constant.int(core.Type.int(), len(LLVM['states']))
            LLVM['states'][name] = cons

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    # Generate state var
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    LLVM['module'].add_global_variable(core.Type.int(), 'state')

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    # Generare process-level vars
    for var_name, (var_type, def_value) in process.variables.viewitems():
        #TODO: Use ASN.1 type instead of hardcoded int type
        var_ptr = LLVM['module'].add_global_variable(core.Type.int(), str(var_name))
        if def_value:
            pass

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    # Generate process functions
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    runtr_func = _generate_runtr_func(process)
    _generate_startup_func(process, process_name, runtr_func)

    print LLVM['module']


def _generate_runtr_func(process):
    '''Generate code for the run_transition function'''
    func_name = 'run_transition'
    func_type = core.Type.function(core.Type.void(), [core.Type.int()])
    func = core.Function.new(LLVM['module'], func_type, func_name)

    entry_block = func.append_basic_block('entry')
    cond_block = func.append_basic_block('cond')
    body_block = func.append_basic_block('body')
    exit_block = func.append_basic_block('exit')

    builder = core.Builder.new(entry_block)
    LLVM['builder'] = builder

    # entry
    id_ptr = builder.alloca(core.Type.int(), None, 'id')
    LLVM['named_values']['id'] = id_ptr
    builder.store(func.args[0], id_ptr)
    builder.branch(cond_block)

    # cond
    builder.position_at_end(cond_block)
    id_ptr = func.args[0]
    no_tr_cons = core.Constant.int(core.Type.int(), -1)
    cond_val = builder.icmp(core.ICMP_NE, id_ptr, no_tr_cons, 'cond')
    builder.cbranch(cond_val, body_block, exit_block)

    # body
    builder.position_at_end(body_block)
    switch = builder.switch(func.args[0], exit_block)

    # transitions
    for idx, tr in enumerate(process.transitions):
        tr_block = func.append_basic_block('tr%d' % idx)
        const = core.Constant.int(core.Type.int(), idx)
        switch.add_case(const, tr_block)
        builder.position_at_end(tr_block)
        generate(tr)
        builder.branch(cond_block)

    # exit
    builder.position_at_end(exit_block)
    builder.ret_void()

    func.verify()
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    LLVM['named_values'].clear()
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    return func


def _generate_startup_func(process, process_name, runtr_func):
    '''Generate code for the startup function'''
    func_name = process_name + '_startup'
    func_type = core.Type.function(core.Type.void(), [])
    func = core.Function.new(LLVM['module'], func_type, func_name)

    entry_block = func.append_basic_block('entry')
    builder = core.Builder.new(entry_block)
    LLVM['builder'] = builder

    # entry
    builder.call(runtr_func, [core.Constant.int(core.Type.int(), 0)])
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    builder.ret_void()

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    func.verify()
    return func
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def write_statement(param, newline):
    ''' Generate the code for the special "write" operator '''
    pass

@generate.register(ogAST.Output)
@generate.register(ogAST.ProcedureCall)
def _call_external_function(output):
    ''' Generate the code of a set of output or procedure call statement '''
    pass


@generate.register(ogAST.TaskAssign)
def _task_assign(task):
    ''' A list of assignments in a task symbol '''
    pass


@generate.register(ogAST.TaskInformalText)
def _task_informal_text(task):
    ''' Generate comments for informal text '''
    pass


@generate.register(ogAST.TaskForLoop)
def _task_forloop(task):
    '''
        Return the code corresponding to a for loop. Two forms are possible:
        for x in range ([start], stop [, step])
        for x in iterable (a SEQUENCE OF)
    '''
    pass

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# ------ expressions --------

@singledispatch
def expression(expr):
    ''' Generate the code for Expression-classes, returning 3 things:
        - list of statements
        - useable string corresponding to the evaluation of the expression,
        - list of local declarations
        (API can differ depending on the backend)
    '''
    _ = expr
    raise TypeError('Unsupported expression: ' + str(expr))
    #return [], '', []


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@expression.register(ogAST.PrimVariable)
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def _primary_variable(prim):
    ''' Single variable reference '''
    pass


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@expression.register(ogAST.PrimPath)
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def _prim_path(primaryId):
    '''
        Return the string of an element list (path)
        cases: a => 'l_a' (reference to a variable)
        a_timer => 'a_timer'  (reference to a timer)
        a!b => a.b (field of a structure)
        a!b if a is a CHOICE => TypeOfa_b_get(a)
        a(Expression) => a(ExpressionSolver) (array index)
        Expression can be complex (if-then-else-fi..)
    '''
    pass


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@expression.register(ogAST.ExprPlus)
@expression.register(ogAST.ExprMul)
@expression.register(ogAST.ExprMinus)
@expression.register(ogAST.ExprEq)
@expression.register(ogAST.ExprNeq)
@expression.register(ogAST.ExprGt)
@expression.register(ogAST.ExprGe)
@expression.register(ogAST.ExprLt)
@expression.register(ogAST.ExprLe)
@expression.register(ogAST.ExprDiv)
@expression.register(ogAST.ExprMod)
@expression.register(ogAST.ExprRem)
@expression.register(ogAST.ExprAssign)
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def _basic_operators(expr):
    ''' Expressions with two sides '''
    pass


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@expression.register(ogAST.ExprOr)
@expression.register(ogAST.ExprAnd)
@expression.register(ogAST.ExprXor)
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def _bitwise_operators(expr):
    ''' Logical operators '''
    pass


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@expression.register(ogAST.ExprAppend)
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def _append(expr):
    ''' Generate code for the APPEND construct: a // b '''
    pass


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@expression.register(ogAST.ExprIn)
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def _expr_in(expr):
    ''' IN expressions: check if item is in a SEQUENCE OF '''
    pass


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@expression.register(ogAST.PrimEnumeratedValue)
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def _enumerated_value(primary):
    ''' Generate code for an enumerated value '''
    pass


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@expression.register(ogAST.PrimChoiceDeterminant)
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def _choice_determinant(primary):
    ''' Generate code for a choice determinant (enumerated) '''
    pass


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@expression.register(ogAST.PrimInteger)
@expression.register(ogAST.PrimReal)
@expression.register(ogAST.PrimBoolean)
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def _integer(primary):
    ''' Generate code for a raw integer/real/boolean value  '''
    pass


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@expression.register(ogAST.PrimEmptyString)
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def _empty_string(primary):
    ''' Generate code for an empty SEQUENCE OF: {} '''
    pass


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@expression.register(ogAST.PrimStringLiteral)
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def _string_literal(primary):
    ''' Generate code for a string (Octet String) '''
    pass


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@expression.register(ogAST.PrimConstant)
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def _constant(primary):
    ''' Generate code for a reference to an ASN.1 constant '''
    pass


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@expression.register(ogAST.PrimMantissaBaseExp)
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def _mantissa_base_exp(primary):
    ''' Generate code for a Real with Mantissa-base-Exponent representation '''
    pass


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@expression.register(ogAST.PrimIfThenElse)
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def _if_then_else(ifThenElse):
    ''' Return string and statements for ternary operator '''
    pass


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@expression.register(ogAST.PrimSequence)
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def _sequence(seq):
    ''' Return Ada string for an ASN.1 SEQUENCE '''
    pass


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@expression.register(ogAST.PrimSequenceOf)
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def _sequence_of(seqof):
    ''' Return Ada string for an ASN.1 SEQUENCE OF '''
    pass


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@expression.register(ogAST.PrimChoiceItem)
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def _choiceitem(choice):
    ''' Return the Ada code for a CHOICE expression '''
    pass


@generate.register(ogAST.Decision)
def _decision(dec):
    ''' generate the code for a decision '''
    pass


@generate.register(ogAST.Label)
def _label(tr):
    ''' Transition following labels are generated in a separate section
        for visibility reasons (see Ada scope)
    '''
    pass


@generate.register(ogAST.Transition)
def _transition(tr):
    ''' generate the code for a transition '''
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    for action in tr.actions:
        generate(action)
        if isinstance(action, ogAST.Label):
            return
    if tr.terminator:
        _generate_terminator(tr.terminator)
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def _generate_terminator(term):
    builder = LLVM['builder']
    id_ptr = LLVM['named_values']['id']
    if term.label:
        pass
    if term.kind == 'next_state':
        state = term.inputString.lower()
        if state.strip() != '-':
            next_id_cons = core.Constant.int(core.Type.int(), term.next_id)
            builder.store(next_id_cons, id_ptr)
            if term.next_id == -1:
                state_ptr = LLVM['module'].get_global_variable_named('state')
                state_id_cons = LLVM['states'][state]
                builder.store(state_id_cons, state_ptr)
        else:
            pass
    elif term.kind == 'join':
        pass
    elif term.kind == 'stop':
        pass
    elif term.kind == 'return':
        pass
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@generate.register(ogAST.Floating_label)
def _floating_label(label):
    ''' Generate the code for a floating label (Ada label + transition) '''
    pass


@generate.register(ogAST.Procedure)
def _inner_procedure(proc):
    ''' Generate the code for a procedure '''
    pass