gem5/src/arch/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.
    # Each element of the dict is a list containing a function and then the
    # arguments to pass to it.
    def doSplitDecode(switchVal, vals, default = None):
        blocks = OutputBlocks()
        blocks.decode_block = 'switch(%s) {\n' % switchVal
        for (val, todo) in vals.items():
            new_blocks = todo[0](*todo[1:])
            new_blocks.decode_block = \
                '\tcase %s: %s\n' % (val, new_blocks.decode_block)
            blocks.append(new_blocks)
        if default:
            new_blocks = default[0](*default[1:])
            new_blocks.decode_block = \
                '\tdefault: %s\n' % new_blocks.decode_block
            blocks.append(new_blocks)
        blocks.decode_block += '}\n'
        return blocks
}};

let {{
    def doRipRelativeDecode(Name, opTypes, env):
        # print "RIPing %s with opTypes %s" % (Name, opTypes)
        normBlocks = specializeInst(Name + "_M", copy.copy(opTypes), copy.copy(env))
        ripBlocks = specializeInst(Name + "_P", copy.copy(opTypes), copy.copy(env))

        blocks = OutputBlocks()
        blocks.append(normBlocks)
        blocks.append(ripBlocks)

        blocks.decode_block = '''
        if(machInst.modRM.mod == 0 &&
          machInst.modRM.rm == 5 &&
          machInst.mode.submode == SixtyFourBitMode)
        { %s }
        else
        { %s }''' % \
         (ripBlocks.decode_block, normBlocks.decode_block)
        return blocks
}};

let {{
    class OpType(object):
        parser = re.compile(r"(?P<tag>[A-Z]+)(?P<size>[a-z]*)|(r(?P<reg>[A-Z0-9]+)(?P<rsize>[a-z]*))")
        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")
            if not self.size:
                self.size = match.group("rsize")

    ModRMRegIndex = "(MODRM_REG | (REX_R << 3))"
    ModRMRMIndex = "(MODRM_RM | (REX_B << 3))"
    InstRegIndex = "(OPCODE_OP_BOTTOM3 | (REX_B << 3))"

    # This function specializes the given piece of code to use a particular
    # set of argument types described by "opTypes".
    def specializeInst(Name, opTypes, env):
        # print "Specializing %s with opTypes %s" % (Name, opTypes)
        while len(opTypes):
            # Parse the operand type string we're working with
            opType = OpType(opTypes[0])
            opTypes.pop(0)

            if opType.tag not in ("I", "J"):
                if opType.size:
                    env.setSize(opType.size)

            if opType.reg:
                #Figure out what to do with fixed register operands
                #This is the index to use, so we should stick it some place.
                if opType.reg in ("A", "B", "C", "D"):
                    env.addReg("INTREG_R%sX" % opType.reg)
                else:
                    env.addReg("INTREG_R%s" % opType.reg)
                Name += "_R"
            elif opType.tag == "B":
                # This refers to registers whose index is encoded as part of the opcode
                Name += "_R"
                env.addReg(InstRegIndex)
            elif opType.tag == "M":
                # This refers to memory. The macroop constructor sets up modrm
                # addressing. Non memory modrm settings should cause an error.
                env.doModRM = True
                return doRipRelativeDecode(Name, opTypes, env)
            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
                env.addReg(ModRMRegIndex)
                Name += "_R"
            elif opType.tag in ("E", "Q", "W"):
                # This might refer to memory or to a register. We need to
                # divide it up farther.
                regEnv = copy.copy(env)
                regEnv.addReg(ModRMRMIndex)
                # This refers to memory. The macroop constructor should set up
                # modrm addressing.
                memEnv = copy.copy(env)
                memEnv.doModRM = True
                return doSplitDecode("MODRM_MOD",
                    {"3" : (specializeInst, Name + "_R", copy.copy(opTypes), regEnv)},
                           (doRipRelativeDecode, Name, copy.copy(opTypes), memEnv))
            elif opType.tag in ("I", "J"):
                # Immediates
                Name += "_I"
            elif opType.tag in ("PR", "R", "VR"):
                # Non register modrm settings should cause an error
                env.addReg(ModRMRMIndex)
                Name += "_R"
            elif opType.tag in ("X", "Y"):
                # This type of memory addressing is for string instructions.
                # They'll use the right index and segment internally.
                Name += "_M"
            else:
                raise Exception, "Unrecognized tag %s." % opType.tag

        # Generate code to return a macroop of the given name which will
        # operate in the "emulation environment" env
        return genMacroop(Name, env)
}};