xref: /gem5/src/arch/arm/isa/formats/branch.isa

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

// Copyright (c) 2007-2008 The Florida State University
// All rights reserved.
//
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// modification, are permitted provided that the following conditions are
// met: redistributions of source code must retain the above copyright
// notice, this list of conditions and the following disclaimer;
// redistributions in binary form must reproduce the above copyright
// notice, this list of conditions and the following disclaimer in the
// documentation and/or other materials provided with the distribution;
// neither the name of the copyright holders nor the names of its
// contributors may be used to endorse or promote products derived from
// this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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//
// Authors: Stephen Hines

////////////////////////////////////////////////////////////////////
//
// Control transfer instructions
//

def format Branch(code,*opt_flags) {{

    #Build Instruction Flags
    #Use Link & Likely Flags to Add Link/Condition Code
    inst_flags = ('IsDirectControl', )
    linking = False
    for x in opt_flags:
        if x == 'Link':
            linking = True
            code += 'LR = NPC;\n'
        else:
            inst_flags += (x, )

    #Take into account uncond. branch instruction
    if 'cond == 1' in code:
         inst_flags += ('IsUnCondControl', )
    else:
         inst_flags += ('IsCondControl', )

    icode =  'if (testPredicate(CondCodes, condCode)) {\n'
    icode += code
    icode += '  NPC = NPC + 4 + disp;\n'
    icode += '} else {\n'
    icode += '  NPC = NPC;\n'
    if linking:
        icode += '  LR = LR;\n'
    icode += '};\n'

    code = icode

    iop = InstObjParams(name, Name, 'Branch', code, inst_flags)
    header_output = BasicDeclare.subst(iop)
    decoder_output = BasicConstructor.subst(iop)
    decode_block = BasicDecode.subst(iop)
    exec_output = BasicExecute.subst(iop)
}};

def format BranchExchange(code,*opt_flags) {{
    #Build Instruction Flags
    #Use Link & Likely Flags to Add Link/Condition Code
    inst_flags = ('IsIndirectControl', )
    linking = False
    for x in opt_flags:
        if x == 'Link':
            linking = True
            code += 'LR = NPC;\n'
        else:
            inst_flags += (x, )

    #Take into account uncond. branch instruction
    if 'cond == 1' in code:
         inst_flags += ('IsUnCondControl', )
    else:
         inst_flags += ('IsCondControl', )

    #Condition code

    icode =  'if (testPredicate(CondCodes, condCode)) {\n'
    icode += code
    icode += '  NPC = Rm & 0xfffffffe; // Masks off bottom bit\n'
    icode += '} else {\n'
    icode += '  NPC = NPC;\n'
    if linking:
        icode += '  LR = LR;\n'
    icode += '};\n'

    code = icode

    iop = InstObjParams(name, Name, 'BranchExchange', code, inst_flags)
    header_output = BasicDeclare.subst(iop)
    decoder_output = BasicConstructor.subst(iop)
    decode_block = BasicDecode.subst(iop)
    exec_output = BasicExecute.subst(iop)
}};

def format Jump(code, *opt_flags) {{
    #Build Instruction Flags
    #Use Link Flag to Add Link Code
    inst_flags = ('IsIndirectControl', 'IsUncondControl')
    for x in opt_flags:
        if x == 'Link':
            code = 'LR = NPC;\n' + code
        elif x == 'ClearHazards':
            code += '/* Code Needed to Clear Execute & Inst Hazards */\n'
        else:
            inst_flags += (x, )

    iop = InstObjParams(name, Name, 'Jump', code, inst_flags)
    header_output = BasicDeclare.subst(iop)
    decoder_output = BasicConstructor.subst(iop)
    decode_block = BasicDecode.subst(iop)
    exec_output = BasicExecute.subst(iop)
    #exec_output = PredOpExecute.subst(iop)
}};