xref: /gem5/src/arch/x86/isa/microasm.isa

// -*- mode:c++ -*-

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// Authors: Gabe Black

////////////////////////////////////////////////////////////////////
//
//  The microcode assembler
//

let {{
    # These are used when setting up microops so that they can specialize their
    # base class template properly.
    RegOpType = "RegisterOperand"
    ImmOpType = "ImmediateOperand"
}};

let {{
    class MicroOpStatement(object):
        def __init__(self):
            self.className = ''
            self.label = ''
            self.args = []

        # This converts a list of python bools into
        # a comma seperated list of C++ bools.
        def microFlagsText(self, vals):
            text = ""
            for val in vals:
                if val:
                    text += ", true"
                else:
                    text += ", false"
            return text

        def getAllocator(self, mnemonic, *microFlags):
            args = ''
            signature = "<"
            emptySig = True
            for arg in self.args:
                if not emptySig:
                    signature += ", "
                emptySig = False
                if arg.has_key("operandImm"):
                    args += ", %s" % arg["operandImm"]
                    signature += ImmOpType
                elif arg.has_key("operandReg"):
                    args += ", %s" % arg["operandReg"]
                    signature += RegOpType
                elif arg.has_key("operandLabel"):
                    raise Exception, "Found a label while creating allocator string."
                else:
                    raise Exception, "Unrecognized operand type."
            signature += ">"
            return 'new %s%s(machInst, %s%s%s)' % (self.className, signature, mnemonic, self.microFlagsText(microFlags), args)
}};

let{{
    def assembleMicro(name, Name, code):

        # This function takes in a block of microcode assembly and returns
        # a python list of objects which describe it.

        # Keep this around in case we need it later
        orig_code = code
        # A list of the statements we've found thus far
        statements = []

        # Regular expressions to pull each piece of the statement out at a
        # time. Each expression expects the thing it's looking for to be at
        # the beginning of the line, so the previous component is stripped
        # before continuing.
        labelRe = re.compile(r'^[ \t]*(?P<label>\w\w*)[ \t]:')
        lineRe = re.compile(r'^(?P<line>..*)(\n|$)')
        classRe = re.compile(r'^[ \t]*(?P<className>[a-zA-Z_]\w*)')
        # This recognizes three different flavors of operands:
        # 1. Raw decimal numbers composed of digits between 0 and 9
        # 2. Code beginning with "{" and continuing until the first "}"
        #         ^ This one might need revising
        # 3. A label, which starts with a capital or small letter, or
        #    underscore, which is optionally followed by a sequence of
        #    capital or small letters, underscores, or digts between 0 and 9
        opRe = re.compile( \
            r'^[ \t]*((\@(?P<operandLabel0>\w\w*))|' +
                    r'(\@\{(?P<operandLabel1>[^}]*)\})|' +
                    r'(\%(?P<operandReg0>\w\w*))|' +
                    r'(\%\{(?P<operandReg1>[^}]*)\})|' +
                    r'(\$(?P<operandImm0>\w\w*))|' +
                    r'(\$\{(?P<operandImm1>[^}]*)\}))')
        lineMatch = lineRe.search(code)
        while lineMatch != None:
            statement = MicroOpStatement()
            # Get a line and seperate it from the rest of the code
            line = lineMatch.group("line")
            orig_line = line
            #print "Parsing line %s" % line
            code = lineRe.sub('', code, 1)

            # Find the label, if any
            labelMatch = labelRe.search(line)
            if labelMatch != None:
                statement.label = labelMatch.group("label")
                #print "Found label %s." % statement.label
            # Clear the label from the statement
            line = labelRe.sub('', line, 1)

            # Find the class name which is roughly equivalent to the op name
            classMatch = classRe.search(line)
            if classMatch == None:
                raise Exception, "Couldn't find class name in statement: %s" \
                        % orig_line
            else:
                statement.className = classMatch.group("className")
                #print "Found class name %s." % statement.className

            # Clear the class name from the statement
            line = classRe.sub('', line, 1)

            #Find as many arguments as you can
            statement.args = []
            opMatch = opRe.search(line)
            while opMatch is not None:
                statement.args.append({})
                # args is a list of dicts which collect different
                # representations of operand values. Different forms might be
                # needed in different places, for instance to replace a label
                # with an offset.
                for opType in ("operandLabel0", "operandReg0", "operandImm0",
                               "operandLabel1", "operandReg1", "operandImm1"):
                    if opMatch.group(opType):
                        statement.args[-1][opType[:-1]] = opMatch.group(opType)
                if len(statement.args[-1]) == 0:
                    print "Problem parsing operand in statement: %s" \
                            % orig_line
                line = opRe.sub('', line, 1)
                #print "Found operand %s." % statement.args[-1]
                opMatch = opRe.search(line)
            #print "Found operands", statement.args

            # Add this statement to our collection
            statements.append(statement)

            # Get the next line
            lineMatch = lineRe.search(code)

        # Decode the labels into displacements

        labels = {}
        micropc = 0
        for statement in statements:
            if statement.label:
                labels[statement.label] = count
            micropc += 1
        micropc = 0
        for statement in statements:
            for arg in statement.args:
                if arg.has_key("operandLabel"):
                    if not labels.has_key(arg["operandLabel"]):
                        raise Exception, "Unrecognized label: %s." % arg["operandLabel"]
                    # This is assuming that intra microcode branches go to
                    # the next micropc + displacement, or
                    # micropc + 1 + displacement.
                    arg["operandImm"] = labels[arg["operandLabel"]] - micropc - 1
            micropc += 1

        if len(statements) == 0:
            raise Exception, "Didn't find any microops in microcode: \n%s" % orig_code

        # If we can implement this instruction with exactly one microop, just
        # use that directly.
        if len(statements) == 1:
            decode_block = "return %s;" % \
                            statements[0].getAllocator('"' + name + '"')
            return ('', '', decode_block, '')
        else:
            # Build a macroop to contain the sequence of microops we've
            # been given.
            return genMacroOp(name, Name, statements)
}};