x86/isa/specialize.isa

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

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// Authors: Gabe Black

////////////////////////////////////////////////////////////////////
//
//  Code to "specialize" a microcode sequence to use a particular
//  variety of operands
//

let {{
    # This code builds up a decode block which decodes based on switchval.
    # vals is a dict which matches case values with what should be decoded to.
    # builder is called on the exploded contents of "vals" values to generate
    # whatever code should be used.
    def doSplitDecode(name, Name, builder, switchVal, vals, default = None):
        blocks = OutputBlocks()
        blocks.decode_block += 'switch(%s) {\n' % switchVal
        for (val, todo) in vals.items():
            built = builder(name, Name, *todo)
            built.decode_block = '\tcase %s: %s\n' % (val, built.decode_block)
            blocks.append(built)
        if default:
            built = builder(name, Name, *default)
            built.decode_block = '\tdefault: %s\n' % built.decode_block
            blocks.append(built)
        blocks.decode_block += '}\n'
        return blocks
}};

let {{
    class OpType(object):
        parser = re.compile(r"(?P<tag>[A-Z][A-Z]*)(?P<size>[a-z][a-z]*)|(r(?P<reg>[A-Za-z0-9][A-Za-z0-9]*))")
        def __init__(self, opTypeString):
            match = OpType.parser.search(opTypeString)
            if match == None:
                raise Exception, "Problem parsing operand type %s" % opTypeString
            self.reg = match.group("reg")
            self.tag = match.group("tag")
            self.size = match.group("size")

    # This function specializes the given piece of code to use a particular
    # set of argument types described by "opTypes". These are "implemented"
    # in reverse order.
    def specializeInst(name, Name, code, opTypes):
        opNum = len(opTypes) - 1
        while len(opTypes):
            # print "Building a composite op with tags", opTypes
            # print "And code", code
            opNum = len(opTypes) - 1
            # A regular expression to find the operand placeholders we're
            # interested in.
            opRe = re.compile("\\^(?P<operandNum>%d)(?=[^0-9]|$)" % opNum)

            # Parse the operand type strign we're working with
            opType = OpType(opTypes[opNum])

            if opType.reg:
                #Figure out what to do with fixed register operands
                if opType.reg in ("Ax", "Bx", "Cx", "Dx"):
                    code = opRe.sub("%%{INTREG_R%s}" % opType.reg.upper(), code)
                elif opType.reg == "Al":
                    # We need a way to specify register width
                    code = opRe.sub("%{INTREG_RAX}", code)
                else:
                    print "Didn't know how to encode fixed register %s!" % opType.reg
            elif opType.tag == None or opType.size == None:
                raise Exception, "Problem parsing operand tag: %s" % opType.tag
            elif opType.tag in ("C", "D", "G", "P", "S", "T", "V"):
                # Use the "reg" field of the ModRM byte to select the register
                code = opRe.sub("%{(uint8_t)MODRM_REG}", code)
            elif opType.tag in ("E", "Q", "W"):
                # This might refer to memory or to a register. We need to
                # divide it up farther.
                regCode = opRe.sub("%{(uint8_t)MODRM_RM}", code)
                regTypes = copy.copy(opTypes)
                regTypes.pop(-1)
                # This needs to refer to memory, but we'll fill in the details
                # later. It needs to take into account unaligned memory
                # addresses.
                code = "GenFault ${new UnimpInstFault}\n" + code
                memCode = opRe.sub("%0", code)
                memTypes = copy.copy(opTypes)
                memTypes.pop(-1)
                return doSplitDecode(name, Name, specializeInst, "MODRM_MOD",
                    {"3" : (regCode, regTypes)}, (memCode, memTypes))
            elif opType.tag in ("I", "J"):
                # Immediates are already in the instruction, so don't leave in
                # those parameters
                code = opRe.sub("${IMMEDIATE}", code)
            elif opType.tag == "M":
                # This needs to refer to memory, but we'll fill in the details
                # later. It needs to take into account unaligned memory
                # addresses.
                code = "GenFault ${new UnimpInstFault}\n" + code
                code = opRe.sub("%0", code)
            elif opType.tag in ("PR", "R", "VR"):
                # There should probably be a check here to verify that mod
                # is equal to 11b
                code = opRe.sub("%{(uint8_t)MODRM_RM}", code)
            else:
                raise Exception, "Unrecognized tag %s." % opType.tag
            opTypes.pop(-1)

        # At this point, we've built up "code" to have all the necessary extra
        # instructions needed to implement whatever types of operands were
        # specified. Now we'll assemble it it into a StaticInst.
        blocks = OutputBlocks()
        blocks.append(assembleMicro(name, Name, code))
        return blocks
}};