path: root/Source/JavaScriptCore/offlineasm/sh4.rb

# Copyright (C) 2013 Apple Inc. All rights reserved.
# Copyright (C) 2013 Cisco Systems, Inc. All rights reserved.
#
# Redistribution and use in source and binary forms, with or without
# modification, are permitted provided that the following conditions
# are met:
# 1. Redistributions of source code must retain the above copyright
#    notice, this list of conditions and the following disclaimer.
# 2. 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.
#
# THIS SOFTWARE IS PROVIDED BY CISCO SYSTEMS, INC. ``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 CISCO SYSTEMS, INC. OR ITS
# 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, DATA, OR
# PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
# OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
# OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

require 'risc'

# GPR conventions, to match the baseline JIT
#
#  r0 => t0, r0
#  r1 => t1, r1
#  r2 => t4
#  r3 => t5
#  r4 =>         a0
#  r5 =>         a1
#  r6 => t2,     a2
#  r7 => t3,     a3
# r10 =>            (scratch)
# r11 =>            (scratch)
# r13 =>            (scratch)
# r14 => cfr
# r15 => sp
#  pr => lr

# FPR conventions, to match the baseline JIT
# We don't have fa2 or fa3!
#  dr0 => ft0, fr
#  dr2 => ft1
#  dr4 => ft2,   fa0
#  dr6 => ft3,   fa1
#  dr8 => ft4
# dr10 => ft5
# dr12 =>             (scratch)

class Node
    def sh4SingleHi
        doubleOperand = sh4Operand
        raise "Bogus register name #{doubleOperand}" unless doubleOperand =~ /^dr/
        "fr" + ($~.post_match.to_i).to_s
    end
    def sh4SingleLo
        doubleOperand = sh4Operand
        raise "Bogus register name #{doubleOperand}" unless doubleOperand =~ /^dr/
        "fr" + ($~.post_match.to_i + 1).to_s
    end
end

class SpecialRegister < NoChildren
    def sh4Operand
        @name
    end

    def dump
        @name
    end

    def register?
        true
    end
end

SH4_TMP_GPRS = [ SpecialRegister.new("r10"), SpecialRegister.new("r11"), SpecialRegister.new("r13") ]
SH4_TMP_FPRS = [ SpecialRegister.new("dr12") ]

class RegisterID
    def sh4Operand
        case name
        when "a0"
            "r4"
        when "a1"
            "r5"
        when "r0", "t0"
            "r0"
        when "r1", "t1"
            "r1"
        when "a2", "t2"
            "r6"
        when "a3", "t3"
            "r7"
        when "t4"
            "r2"
        when "t5"
            "r3"
        when "cfr"
            "r14"
        when "sp"
            "r15"
        when "lr"
            "pr"
        else
            raise "Bad register #{name} for SH4 at #{codeOriginString}"
        end
    end
end

class FPRegisterID
    def sh4Operand
        case name
        when "ft0", "fr"
            "dr0"
        when "ft1"
            "dr2"
        when "ft2", "fa0"
            "dr4"
        when "ft3", "fa1"
            "dr6"
        when "ft4"
            "dr8"
        when "ft5"
            "dr10"
        else
            raise "Bad register #{name} for SH4 at #{codeOriginString}"
        end
    end
end

class Immediate
    def sh4Operand
        raise "Invalid immediate #{value} at #{codeOriginString}" if value < -128 or value > 127
        "##{value}"
    end
end

class Address
    def sh4Operand
        raise "Bad offset #{offset.value} at #{codeOriginString}" if offset.value < 0 or offset.value > 60
        if offset.value == 0
            "@#{base.sh4Operand}"
        else
            "@(#{offset.value}, #{base.sh4Operand})"
        end
    end

    def sh4OperandPostInc
        raise "Bad offset #{offset.value} for post inc at #{codeOriginString}" unless offset.value == 0
        "@#{base.sh4Operand}+"
    end

    def sh4OperandPreDec
        raise "Bad offset #{offset.value} for pre dec at #{codeOriginString}" unless offset.value == 0
        "@-#{base.sh4Operand}"
    end
end

class BaseIndex
    def sh4Operand
        raise "Unconverted base index at #{codeOriginString}"
    end
end

class AbsoluteAddress
    def sh4Operand
        raise "Unconverted absolute address at #{codeOriginString}"
    end
end

class LabelReference
    def sh4Operand
        value
    end
end

class SubImmediates < Node
    def sh4Operand
        "#{@left.sh4Operand} - #{@right.sh4Operand}"
    end
end

class ConstPool < Node
    attr_reader :size
    attr_reader :entries

    def initialize(codeOrigin, entries, size)
        super(codeOrigin)
        raise "Invalid size #{size} for ConstPool" unless size == 16 or size == 32
        @size = size
        @entries = entries
    end
    
    def dump
        "#{size}: #{entries}"
    end
    
    def address?
        false
    end
    
    def label?
        false
    end
    
    def immediate?
        false
    end
    
    def register?
        false
    end

    def lowerSH4
        if size == 16
            $asm.puts ".balign 2"
        else
            $asm.puts ".balign 4"
        end
        entries.map {
            |e|
            e.label.lower("SH4")
            if e.size == 16
                $asm.puts ".word #{e.value}"
            else
                $asm.puts ".long #{e.value}"
            end
        }
    end
end

class ConstPoolEntry < Node
    attr_reader :size
    attr_reader :value
    attr_reader :label
    attr_reader :labelref
    
    def initialize(codeOrigin, value, size)
        super(codeOrigin)
        raise "Invalid size #{size} for ConstPoolEntry" unless size == 16 or size == 32
        @size = size
        @value = value
        @label = LocalLabel.unique("constpool#{size}")
        @labelref = LocalLabelReference.new(codeOrigin, label)
    end
    
    def dump
        "#{value} (#{size} @ #{label})"
    end
    
    def ==(other)
        other.is_a? ConstPoolEntry and other.value == @value
    end
    
    def address?
        false
    end
    
    def label?
        false
    end
    
    def immediate?
        false
    end
    
    def register?
        false
    end
end


#
# Lowering of shift ops for SH4. For example:
#
# rshifti foo, bar
#
# becomes:
#
# negi foo, tmp
# shad tmp, bar
#

def sh4LowerShiftOps(list)
    newList = []
    list.each {
        | node |
        if node.is_a? Instruction
            case node.opcode
            when "ulshifti", "ulshiftp", "urshifti", "urshiftp", "lshifti", "lshiftp", "rshifti", "rshiftp"
                if node.opcode[0, 1] == "u"
                    type = "l"
                    direction = node.opcode[1, 1]
                else
                    type = "a"
                    direction = node.opcode[0, 1]
                end
                if node.operands[0].is_a? Immediate
                    maskedImm = Immediate.new(node.operands[0].codeOrigin, node.operands[0].value & 31)
                    if maskedImm.value == 0
                        # There is nothing to do here.
                    elsif maskedImm.value == 1 or (type == "l" and [2, 8, 16].include? maskedImm.value)
                        newList << Instruction.new(node.codeOrigin, "sh#{type}#{direction}x", [maskedImm, node.operands[1]])
                    else
                        tmp = Tmp.new(node.codeOrigin, :gpr)
                        if direction == "l"
                            newList << Instruction.new(node.codeOrigin, "move", [maskedImm, tmp])
                        else
                            newList << Instruction.new(node.codeOrigin, "move", [Immediate.new(node.operands[0].codeOrigin, -1 * maskedImm.value), tmp])
                        end
                        newList << Instruction.new(node.codeOrigin, "sh#{type}d", [tmp, node.operands[1]])
                    end
                else
                    tmp = Tmp.new(node.codeOrigin, :gpr)
                    newList << Instruction.new(node.codeOrigin, "move", [Immediate.new(node.operands[0].codeOrigin, 31), tmp])
                    newList << Instruction.new(node.codeOrigin, "andi", [node.operands[0], tmp])
                    if direction == "r"
                        newList << Instruction.new(node.codeOrigin, "negi", [tmp, tmp])
                    end
                    newList << Instruction.new(node.codeOrigin, "sh#{type}d", [tmp, node.operands[1]])
                end
            else
                newList << node
            end
        else
            newList << node
        end
    }
    newList
end


#
# Lowering of simple branch ops for SH4. For example:
#
# baddis foo, bar, baz
#
# will become:
#
# addi foo, bar
# bs bar, baz
#

def sh4LowerSimpleBranchOps(list)
    newList = []
    list.each {
        | node |
        if node.is_a? Instruction
            annotation = node.annotation
            case node.opcode
            when /^b(addi|subi|ori|addp)/
                op = $1
                bc = $~.post_match

                case op
                when "addi", "addp"
                    op = "addi"
                when "subi", "subp"
                    op = "subi"
                when "ori", "orp"
                    op = "ori"
                end

                if bc == "s"
                    raise "Invalid operands number (#{node.operands.size})" unless node.operands.size == 3
                    if node.operands[1].is_a? RegisterID or node.operands[1].is_a? SpecialRegister
                        newList << Instruction.new(node.codeOrigin, op, node.operands[0..1])
                        newList << Instruction.new(node.codeOrigin, "bs", node.operands[1..2])
                    else
                        tmpVal = Tmp.new(node.codeOrigin, :gpr)
                        tmpPtr = Tmp.new(node.codeOrigin, :gpr)
                        addr = Address.new(node.codeOrigin, tmpPtr, Immediate.new(node.codeOrigin, 0))
                        newList << Instruction.new(node.codeOrigin, "leap", [node.operands[1], tmpPtr])
                        newList << Instruction.new(node.codeOrigin, "loadi", [addr, tmpVal])
                        newList << Instruction.new(node.codeOrigin, op, [node.operands[0], tmpVal])
                        newList << Instruction.new(node.codeOrigin, "storei", [tmpVal, addr])
                        newList << Instruction.new(node.codeOrigin, "bs", [tmpVal, node.operands[2]])
                    end
                elsif bc == "nz"
                    raise "Invalid operands number (#{node.operands.size})" unless node.operands.size == 3
                    newList << Instruction.new(node.codeOrigin, op, node.operands[0..1])
                    newList << Instruction.new(node.codeOrigin, "btinz", node.operands[1..2])
                else
                    newList << node
                end
            when "bmulio", "bmulpo"
                raise "Invalid operands number (#{node.operands.size})" unless node.operands.size == 3
                tmp1 = Tmp.new(node.codeOrigin, :gpr)
                tmp2 = Tmp.new(node.codeOrigin, :gpr)
                newList << Instruction.new(node.codeOrigin, node.opcode, [tmp1, tmp2].concat(node.operands))
            else
                newList << node
            end
        else
            newList << node
        end
    }
    newList
end


#
# Lowering of double accesses for SH4. For example:
#
# loadd [foo, bar, 8], baz
#
# becomes:
#
# leap [foo, bar, 8], tmp
# loaddReversedAndIncrementAddress [tmp], baz
#

def sh4LowerDoubleAccesses(list)
    newList = []
    list.each {
        | node |
        if node.is_a? Instruction
            case node.opcode
            when "loadd"
                tmp = Tmp.new(codeOrigin, :gpr)
                addr = Address.new(codeOrigin, tmp, Immediate.new(codeOrigin, 0))
                newList << Instruction.new(codeOrigin, "leap", [node.operands[0], tmp])
                newList << Instruction.new(node.codeOrigin, "loaddReversedAndIncrementAddress", [addr, node.operands[1]], node.annotation)
            when "stored"
                tmp = Tmp.new(codeOrigin, :gpr)
                addr = Address.new(codeOrigin, tmp, Immediate.new(codeOrigin, 0))
                newList << Instruction.new(codeOrigin, "leap", [node.operands[1].withOffset(8), tmp])
                newList << Instruction.new(node.codeOrigin, "storedReversedAndDecrementAddress", [node.operands[0], addr], node.annotation)
            else
                newList << node
            end
        else
            newList << node
        end
    }
    newList
end


#
# Lowering of double specials for SH4.
#

def sh4LowerDoubleSpecials(list)
    newList = []
    list.each {
        | node |
        if node.is_a? Instruction
            case node.opcode
            when "bdltun", "bdgtun"
                # Handle specific floating point unordered opcodes.
                newList << Instruction.new(codeOrigin, "bdnan", [node.operands[0], node.operands[2]])
                newList << Instruction.new(codeOrigin, "bdnan", [node.operands[1], node.operands[2]])
                newList << Instruction.new(codeOrigin, node.opcode[0..-3], node.operands)
            when "bdnequn", "bdgtequn", "bdltequn"
                newList << Instruction.new(codeOrigin, node.opcode[0..-3], node.operands)
            when "bdneq", "bdgteq", "bdlteq"
                # Handle specific floating point ordered opcodes.
                outlabel = LocalLabel.unique("out_#{node.opcode}")
                outref = LocalLabelReference.new(codeOrigin, outlabel)
                newList << Instruction.new(codeOrigin, "bdnan", [node.operands[0], outref])
                newList << Instruction.new(codeOrigin, "bdnan", [node.operands[1], outref])
                newList << Instruction.new(codeOrigin, node.opcode, node.operands)
                newList << outlabel
            else
                newList << node
            end
        else
            newList << node
        end
    }
    newList
end


#
# Lowering of misplaced labels for SH4.
#

def sh4LowerMisplacedLabels(list)
    newList = []
    list.each {
        | node |
        if node.is_a? Instruction
            operands = node.operands
            newOperands = []
            operands.each {
                | operand |
                if operand.is_a? LabelReference and node.opcode != "mova"
                    tmp = Tmp.new(operand.codeOrigin, :gpr)
                    newList << Instruction.new(operand.codeOrigin, "move", [operand, tmp])
                    newOperands << tmp
                else
                    newOperands << operand
                end
            }
            newList << Instruction.new(node.codeOrigin, node.opcode, newOperands, node.annotation)
        else
            newList << node
        end
    }
    newList
end


#
# Lowering of misplaced special registers for SH4. For example:
#
# storep pr, foo
#
# becomes:
#
# stspr tmp
# storep tmp, foo
#

def sh4LowerMisplacedSpecialRegisters(list)
    newList = []
    list.each {
        | node |
        if node.is_a? Instruction
            case node.opcode
            when "move"
                if node.operands[0].is_a? RegisterID and node.operands[0].sh4Operand == "pr"
                    newList << Instruction.new(codeOrigin, "stspr", [node.operands[1]])
                elsif node.operands[1].is_a? RegisterID and node.operands[1].sh4Operand == "pr"
                    newList << Instruction.new(codeOrigin, "ldspr", [node.operands[0]])
                else
                    newList << node
                end
            when "loadi", "loadis", "loadp"
                if node.operands[1].is_a? RegisterID and node.operands[1].sh4Operand == "pr"
                    tmp = Tmp.new(codeOrigin, :gpr)
                    newList << Instruction.new(codeOrigin, node.opcode, [node.operands[0], tmp])
                    newList << Instruction.new(codeOrigin, "ldspr", [tmp])
                else
                    newList << node
                end
            when "storei", "storep"
                if node.operands[0].is_a? RegisterID and node.operands[0].sh4Operand == "pr"
                    tmp = Tmp.new(codeOrigin, :gpr)
                    newList << Instruction.new(codeOrigin, "stspr", [tmp])
                    newList << Instruction.new(codeOrigin, node.opcode, [tmp, node.operands[1]])
                else
                    newList << node
                end
            else
                newList << node
            end
        else
            newList << node
        end
    }
    newList
end


#
# Group immediate values outside -128..127 range into constant pools for SH4.
# These constant pools will be placed behind non-return opcodes jmp and ret, for example:
#
# move 1024, foo
# ...
# ret
#
# becomes:
#
# move [label], foo
# ...
# ret
# label: 1024
#

def sh4LowerConstPool(list)
    newList = []
    currentPool16 = []
    currentPool32 = []
    list.each {
        | node |
        if node.is_a? Instruction
            case node.opcode
            when "jmp", "ret", "flushcp"
                if node.opcode == "flushcp"
                    outlabel = LocalLabel.unique("flushcp")
                    newList << Instruction.new(codeOrigin, "jmp", [LocalLabelReference.new(codeOrigin, outlabel)])
                else
                    newList << node
                end
                if not currentPool16.empty?
                    newList << ConstPool.new(codeOrigin, currentPool16, 16)
                    currentPool16 = []
                end
                if not currentPool32.empty?
                    newList << ConstPool.new(codeOrigin, currentPool32, 32)
                    currentPool32 = []
                end
                if node.opcode == "flushcp"
                    newList << outlabel
                end
            when "move"
                if node.operands[0].is_a? Immediate and not (-128..127).include? node.operands[0].value
                    poolEntry = nil
                    if (-32768..32767).include? node.operands[0].value
                        currentPool16.each { |e|
                            if e.value == node.operands[0].value
                                poolEntry = e
                            end
                        }
                        if !poolEntry
                            poolEntry = ConstPoolEntry.new(codeOrigin, node.operands[0].value, 16)
                            currentPool16 << poolEntry
                        end
                    else
                        currentPool32.each { |e|
                            if e.value == node.operands[0].value
                                poolEntry = e
                            end
                        }
                        if !poolEntry
                            poolEntry = ConstPoolEntry.new(codeOrigin, node.operands[0].value, 32)
                            currentPool32 << poolEntry
                        end
                    end
                    newList << Instruction.new(codeOrigin, "move", [poolEntry, node.operands[1]])
                elsif node.operands[0].is_a? LabelReference
                    poolEntry = nil
                    currentPool32.each { |e|
                        if e.value == node.operands[0].asmLabel
                            poolEntry = e
                        end
                    }
                    if !poolEntry
                        poolEntry = ConstPoolEntry.new(codeOrigin, node.operands[0].asmLabel, 32)
                        currentPool32 << poolEntry
                    end
                    newList << Instruction.new(codeOrigin, "move", [poolEntry, node.operands[1]])
                elsif node.operands[0].is_a? SubImmediates
                    poolEntry = ConstPoolEntry.new(codeOrigin, node.operands[0].sh4Operand, 32)
                    currentPool32 << poolEntry
                    newList << Instruction.new(codeOrigin, "move", [poolEntry, node.operands[1]])
                else
                    newList << node
                end
            else
                newList << node
            end
        else
            newList << node
        end
    }
    if not currentPool16.empty?
        newList << ConstPool.new(codeOrigin, currentPool16, 16)
    end
    if not currentPool32.empty?
        newList << ConstPool.new(codeOrigin, currentPool32, 32)
    end
    newList
end


#
# Lowering of argument setup for SH4.
# This phase avoids argument register trampling. For example, if a0 == t4:
#
# setargs t1, t4
#
# becomes:
#
# move t4, a1
# move t1, a0
#

def sh4LowerArgumentSetup(list)
    a0 = RegisterID.forName(codeOrigin, "a0")
    a1 = RegisterID.forName(codeOrigin, "a1")
    a2 = RegisterID.forName(codeOrigin, "a2")
    a3 = RegisterID.forName(codeOrigin, "a3")
    newList = []
    list.each {
        | node |
        if node.is_a? Instruction
            case node.opcode
            when "setargs"
                if node.operands.size == 2
                    if node.operands[1].sh4Operand != a0.sh4Operand
                        newList << Instruction.new(codeOrigin, "move", [node.operands[0], a0])
                        newList << Instruction.new(codeOrigin, "move", [node.operands[1], a1])
                    elsif node.operands[0].sh4Operand != a1.sh4Operand
                        newList << Instruction.new(codeOrigin, "move", [node.operands[1], a1])
                        newList << Instruction.new(codeOrigin, "move", [node.operands[0], a0])
                    else
                        # As (operands[0] == a1) and (operands[1] == a0), we just need to swap a0 and a1.
                        newList << Instruction.new(codeOrigin, "xori", [a0, a1])
                        newList << Instruction.new(codeOrigin, "xori", [a1, a0])
                        newList << Instruction.new(codeOrigin, "xori", [a0, a1])
                    end
                elsif node.operands.size == 4
                    # FIXME: We just raise an error if something is likely to go wrong for now.
                    # It would be better to implement a recovering algorithm.
                    if (node.operands[0].sh4Operand == a1.sh4Operand) or
                        (node.operands[0].sh4Operand == a2.sh4Operand) or
                        (node.operands[0].sh4Operand == a3.sh4Operand) or
                        (node.operands[1].sh4Operand == a0.sh4Operand) or
                        (node.operands[1].sh4Operand == a2.sh4Operand) or
                        (node.operands[1].sh4Operand == a3.sh4Operand) or
                        (node.operands[2].sh4Operand == a0.sh4Operand) or
                        (node.operands[2].sh4Operand == a1.sh4Operand) or
                        (node.operands[2].sh4Operand == a3.sh4Operand) or
                        (node.operands[3].sh4Operand == a0.sh4Operand) or
                        (node.operands[3].sh4Operand == a1.sh4Operand) or
                        (node.operands[3].sh4Operand == a2.sh4Operand)
                        raise "Potential argument register trampling detected."
                    end

                    newList << Instruction.new(codeOrigin, "move", [node.operands[0], a0])
                    newList << Instruction.new(codeOrigin, "move", [node.operands[1], a1])
                    newList << Instruction.new(codeOrigin, "move", [node.operands[2], a2])
                    newList << Instruction.new(codeOrigin, "move", [node.operands[3], a3])
                else
                    raise "Invalid operands number (#{node.operands.size}) for setargs"
                end
            else
                newList << node
            end
        else
            newList << node
        end
    }
    newList
end


class Sequence
    def getModifiedListSH4
        result = @list

        # Verify that we will only see instructions and labels.
        result.each {
            | node |
            unless node.is_a? Instruction or
                    node.is_a? Label or
                    node.is_a? LocalLabel or
                    node.is_a? Skip
                raise "Unexpected #{node.inspect} at #{node.codeOrigin}"
            end
        }

        result = sh4LowerShiftOps(result)
        result = sh4LowerSimpleBranchOps(result)
        result = riscLowerMalformedAddresses(result) {
            | node, address |
            if address.is_a? Address
                case node.opcode
                when "btbz", "btbnz", "cbeq", "bbeq", "bbneq", "bbb", "loadb", "storeb"
                    (0..15).include? address.offset.value and
                        ((node.operands[0].is_a? RegisterID and node.operands[0].sh4Operand == "r0") or
                         (node.operands[1].is_a? RegisterID and node.operands[1].sh4Operand == "r0"))
                when "loadh"
                    (0..30).include? address.offset.value and
                        ((node.operands[0].is_a? RegisterID and node.operands[0].sh4Operand == "r0") or
                         (node.operands[1].is_a? RegisterID and node.operands[1].sh4Operand == "r0"))
                else
                    (0..60).include? address.offset.value
                end
            else
                false
            end
        }
        result = sh4LowerDoubleAccesses(result)
        result = sh4LowerDoubleSpecials(result)
        result = riscLowerMisplacedImmediates(result, ["storeb", "storei", "storep", "muli", "mulp", "andi", "ori", "xori",
            "cbeq", "cieq", "cpeq", "cineq", "cpneq", "cib", "baddio", "bsubio", "bmulio", "baddis",
            "bbeq", "bbneq", "bbb", "bieq", "bpeq", "bineq", "bpneq", "bia", "bpa", "biaeq", "bpaeq", "bib", "bpb",
            "bigteq", "bpgteq", "bilt", "bplt", "bigt", "bpgt", "bilteq", "bplteq", "btiz", "btpz", "btinz", "btpnz", "btbz", "btbnz"])
        result = riscLowerMalformedImmediates(result, -128..127)
        result = riscLowerMisplacedAddresses(result)
        result = sh4LowerMisplacedLabels(result)
        result = sh4LowerMisplacedSpecialRegisters(result)

        result = assignRegistersToTemporaries(result, :gpr, SH4_TMP_GPRS)
        result = assignRegistersToTemporaries(result, :gpr, SH4_TMP_FPRS)

        result = sh4LowerConstPool(result)
        result = sh4LowerArgumentSetup(result)

        return result
    end
end

def sh4Operands(operands)
    operands.map{|v| v.sh4Operand}.join(", ")
end

def emitSH4Branch(sh4opcode, operand)
    raise "Invalid operand #{operand}" unless operand.is_a? RegisterID or operand.is_a? SpecialRegister
    $asm.puts "#{sh4opcode} @#{operand.sh4Operand}"
    $asm.puts "nop"
end

def emitSH4ShiftImm(val, operand, direction)
    tmp = val
    while tmp > 0
        if tmp >= 16
            $asm.puts "shl#{direction}16 #{operand.sh4Operand}"
            tmp -= 16
        elsif tmp >= 8
            $asm.puts "shl#{direction}8 #{operand.sh4Operand}"
            tmp -= 8
        elsif tmp >= 2
            $asm.puts "shl#{direction}2 #{operand.sh4Operand}"
            tmp -= 2
        else
            $asm.puts "shl#{direction} #{operand.sh4Operand}"
            tmp -= 1
        end
    end
end

def emitSH4BranchIfT(dest, neg)
    outlabel = LocalLabel.unique("branchIfT")
    sh4opcode = neg ? "bt" : "bf"
    $asm.puts "#{sh4opcode} #{LocalLabelReference.new(codeOrigin, outlabel).asmLabel}"
    if dest.is_a? LocalLabelReference
        $asm.puts "bra #{dest.asmLabel}"
        $asm.puts "nop"
    else
        emitSH4Branch("jmp", dest)
    end
    outlabel.lower("SH4")
end

def emitSH4IntCompare(cmpOpcode, operands)
    $asm.puts "cmp/#{cmpOpcode} #{sh4Operands([operands[1], operands[0]])}"
end

def emitSH4CondBranch(cmpOpcode, neg, operands)
    emitSH4IntCompare(cmpOpcode, operands)
    emitSH4BranchIfT(operands[2], neg)
end

def emitSH4CompareSet(cmpOpcode, neg, operands)
    emitSH4IntCompare(cmpOpcode, operands)
    if !neg
        $asm.puts "movt #{operands[2].sh4Operand}"
    else
        outlabel = LocalLabel.unique("compareSet")
        $asm.puts "mov #0, #{operands[2].sh4Operand}"
        $asm.puts "bt #{LocalLabelReference.new(codeOrigin, outlabel).asmLabel}"
        $asm.puts "mov #1, #{operands[2].sh4Operand}"
        outlabel.lower("SH4")
    end
end

def emitSH4BranchIfNaN(operands)
    raise "Invalid operands number (#{operands.size})" unless operands.size == 2
    $asm.puts "fcmp/eq #{sh4Operands([operands[0], operands[0]])}"
    $asm.puts "bf #{operands[1].asmLabel}"
end

def emitSH4DoubleCondBranch(cmpOpcode, neg, operands)
    if cmpOpcode == "lt"
        $asm.puts "fcmp/gt #{sh4Operands([operands[0], operands[1]])}"
    else
        $asm.puts "fcmp/#{cmpOpcode} #{sh4Operands([operands[1], operands[0]])}"
    end
    emitSH4BranchIfT(operands[2], neg)
end

class Instruction
    def lowerSH4
        $asm.comment codeOriginString
        case opcode
        when "addi", "addp"
            if operands.size == 3
                if operands[0].sh4Operand == operands[2].sh4Operand
                    $asm.puts "add #{sh4Operands([operands[1], operands[2]])}"
                elsif operands[1].sh4Operand == operands[2].sh4Operand
                    $asm.puts "add #{sh4Operands([operands[0], operands[2]])}"
                else
                    $asm.puts "mov #{sh4Operands([operands[0], operands[2]])}"
                    $asm.puts "add #{sh4Operands([operands[1], operands[2]])}"
                end
            else
                $asm.puts "add #{sh4Operands(operands)}"
            end
        when "subi", "subp"
            if operands.size == 3
                if operands[1].is_a? Immediate
                    $asm.puts "mov #{sh4Operands([Immediate.new(codeOrigin, -1 * operands[1].value), operands[2]])}"
                    $asm.puts "add #{sh4Operands([operands[0], operands[2]])}"
                elsif operands[1].sh4Operand == operands[2].sh4Operand
                    $asm.puts "neg #{sh4Operands([operands[2], operands[2]])}"
                    $asm.puts "add #{sh4Operands([operands[0], operands[2]])}"
                else
                    $asm.puts "mov #{sh4Operands([operands[0], operands[2]])}"
                    $asm.puts "sub #{sh4Operands([operands[1], operands[2]])}"
                end
            else
                if operands[0].is_a? Immediate
                    $asm.puts "add #{sh4Operands([Immediate.new(codeOrigin, -1 * operands[0].value), operands[1]])}"
                else
                    $asm.puts "sub #{sh4Operands(operands)}"
                end
            end
        when "muli", "mulp"
            $asm.puts "mul.l #{sh4Operands(operands[0..1])}"
            $asm.puts "sts macl, #{operands[-1].sh4Operand}"
        when "negi", "negp"
            if operands.size == 2
                $asm.puts "neg #{sh4Operands(operands)}"
            else
                $asm.puts "neg #{sh4Operands([operands[0], operands[0]])}"
            end
        when "andi", "andp", "ori", "orp", "xori", "xorp"
            raise "#{opcode} with #{operands.size} operands is not handled yet" unless operands.size == 2
            sh4opcode = opcode[0..-2]
            $asm.puts "#{sh4opcode} #{sh4Operands(operands)}"
        when "shllx", "shlrx"
            raise "Unhandled parameters for opcode #{opcode}" unless operands[0].is_a? Immediate
            if operands[0].value == 1
                $asm.puts "shl#{opcode[3, 1]} #{operands[1].sh4Operand}"
            else
                $asm.puts "shl#{opcode[3, 1]}#{operands[0].value} #{operands[1].sh4Operand}"
            end
        when "shalx", "sharx"
            raise "Unhandled parameters for opcode #{opcode}" unless operands[0].is_a? Immediate and operands[0].value == 1
            $asm.puts "sha#{opcode[3, 1]} #{operands[1].sh4Operand}"
        when "shld", "shad"
            $asm.puts "#{opcode} #{sh4Operands(operands)}"
        when "loaddReversedAndIncrementAddress"
            # As we are little endian, we don't use "fmov @Rm, DRn" here.
            $asm.puts "fmov.s #{operands[0].sh4OperandPostInc}, #{operands[1].sh4SingleLo}"
            $asm.puts "fmov.s #{operands[0].sh4OperandPostInc}, #{operands[1].sh4SingleHi}"
        when "storedReversedAndDecrementAddress"
            # As we are little endian, we don't use "fmov DRm, @Rn" here.
            $asm.puts "fmov.s #{operands[0].sh4SingleHi}, #{operands[1].sh4OperandPreDec}"
            $asm.puts "fmov.s #{operands[0].sh4SingleLo}, #{operands[1].sh4OperandPreDec}"
        when "ci2d"
            $asm.puts "lds #{operands[0].sh4Operand}, fpul"
            $asm.puts "float fpul, #{operands[1].sh4Operand}"
        when "fii2d"
            $asm.puts "lds #{operands[0].sh4Operand}, fpul"
            $asm.puts "fsts fpul, #{operands[2].sh4SingleLo}"
            $asm.puts "lds #{operands[1].sh4Operand}, fpul"
            $asm.puts "fsts fpul, #{operands[2].sh4SingleHi}"
        when "fd2ii"
            $asm.puts "flds #{operands[0].sh4SingleLo}, fpul"
            $asm.puts "sts fpul, #{operands[1].sh4Operand}"
            $asm.puts "flds #{operands[0].sh4SingleHi}, fpul"
            $asm.puts "sts fpul, #{operands[2].sh4Operand}"
        when "addd", "subd", "muld", "divd"
            sh4opcode = opcode[0..-2]
            $asm.puts "f#{sh4opcode} #{sh4Operands(operands)}"
        when "bcd2i"
            $asm.puts "ftrc #{operands[0].sh4Operand}, fpul"
            $asm.puts "sts fpul, #{operands[1].sh4Operand}"
            $asm.puts "float fpul, #{SH4_TMP_FPRS[0].sh4Operand}"
            $asm.puts "fcmp/eq #{sh4Operands([operands[0], SH4_TMP_FPRS[0]])}"
            $asm.puts "bf #{operands[2].asmLabel}"
            $asm.puts "tst #{sh4Operands([operands[1], operands[1]])}"
            $asm.puts "bt #{operands[2].asmLabel}"
        when "bdnan"
            emitSH4BranchIfNaN(operands)
        when "bdneq"
            emitSH4DoubleCondBranch("eq", true, operands)
        when "bdgteq"
            emitSH4DoubleCondBranch("lt", true, operands)
        when "bdlt"
            emitSH4DoubleCondBranch("lt", false, operands)
        when "bdlteq"
            emitSH4DoubleCondBranch("gt", true, operands)
        when "bdgt"
            emitSH4DoubleCondBranch("gt", false, operands)
        when "baddio", "baddpo", "bsubio", "bsubpo"
            raise "#{opcode} with #{operands.size} operands is not handled yet" unless operands.size == 3
            $asm.puts "#{opcode[1, 3]}v #{sh4Operands([operands[0], operands[1]])}"
            $asm.puts "bt #{operands[2].asmLabel}"
        when "bmulio", "bmulpo"
            raise "Invalid operands number (#{operands.size})" unless operands.size == 5
            $asm.puts "dmuls.l #{sh4Operands([operands[2], operands[3]])}"
            $asm.puts "sts macl, #{operands[3].sh4Operand}"
            $asm.puts "cmp/pz #{operands[3].sh4Operand}"
            $asm.puts "movt #{operands[1].sh4Operand}"
            $asm.puts "add #-1, #{operands[1].sh4Operand}"
            $asm.puts "sts mach, #{operands[0].sh4Operand}"
            $asm.puts "cmp/eq #{sh4Operands([operands[0], operands[1]])}"
            $asm.puts "bf #{operands[4].asmLabel}"
        when "btiz", "btpz", "btbz", "btinz", "btpnz", "btbnz"
            if operands.size == 3
                $asm.puts "tst #{sh4Operands([operands[0], operands[1]])}"
            else
                if operands[0].sh4Operand == "r0"
                    $asm.puts "cmp/eq #0, r0"
                else
                    $asm.puts "tst #{sh4Operands([operands[0], operands[0]])}"
                end
            end
            emitSH4BranchIfT(operands[-1], (opcode[-2, 2] == "nz"))
        when "cieq", "cpeq", "cbeq"
            emitSH4CompareSet("eq", false, operands)
        when "cineq", "cpneq", "cbneq"
            emitSH4CompareSet("eq", true, operands)
        when "cib", "cpb", "cbb"
            emitSH4CompareSet("hs", true, operands)
        when "bieq", "bpeq", "bbeq"
            emitSH4CondBranch("eq", false, operands)
        when "bineq", "bpneq", "bbneq"
            emitSH4CondBranch("eq", true, operands)
        when "bib", "bpb", "bbb"
            emitSH4CondBranch("hs", true, operands)
        when "bia", "bpa", "bba"
            emitSH4CondBranch("hi", false, operands)
        when "bibeq", "bpbeq"
            emitSH4CondBranch("hi", true, operands)
        when "biaeq", "bpaeq"
            emitSH4CondBranch("hs", false, operands)
        when "bigteq", "bpgteq", "bbgteq"
            emitSH4CondBranch("ge", false, operands)
        when "bilt", "bplt", "bblt"
            emitSH4CondBranch("ge", true, operands)
        when "bigt", "bpgt", "bbgt"
            emitSH4CondBranch("gt", false, operands)
        when "bilteq", "bplteq", "bblteq"
            emitSH4CondBranch("gt", true, operands)
        when "bs"
            $asm.puts "cmp/pz #{operands[0].sh4Operand}"
            $asm.puts "bf #{operands[1].asmLabel}"
        when "call"
            if operands[0].is_a? LocalLabelReference
                $asm.puts "bsr #{operands[0].asmLabel}"
                $asm.puts "nop"
            elsif operands[0].is_a? RegisterID or operands[0].is_a? SpecialRegister
                emitSH4Branch("jsr", operands[0])
            else
                raise "Unhandled parameters for opcode #{opcode} at #{codeOriginString}"
            end
        when "jmp"
            if operands[0].is_a? LocalLabelReference
                $asm.puts "bra #{operands[0].asmLabel}"
                $asm.puts "nop"
            elsif operands[0].is_a? RegisterID or operands[0].is_a? SpecialRegister
                emitSH4Branch("jmp", operands[0])
            else
                raise "Unhandled parameters for opcode #{opcode} at #{codeOriginString}"
            end
        when "ret"
            $asm.puts "rts"
            $asm.puts "nop"
        when "loadb"
            $asm.puts "mov.b #{sh4Operands(operands)}"
            $asm.puts "extu.b #{sh4Operands([operands[1], operands[1]])}"
        when "storeb"
            $asm.puts "mov.b #{sh4Operands(operands)}"
        when "loadh"
            $asm.puts "mov.w #{sh4Operands(operands)}"
            $asm.puts "extu.w #{sh4Operands([operands[1], operands[1]])}"
        when "loadi", "loadis", "loadp", "storei", "storep"
            $asm.puts "mov.l #{sh4Operands(operands)}"
        when "alignformova"
            $asm.puts ".balign 4" # As balign directive is in a code section, fill value is 'nop' instruction.
        when "mova"
            $asm.puts "mova #{sh4Operands(operands)}"
        when "move"
            if operands[0].is_a? ConstPoolEntry
                if operands[0].size == 16
                    $asm.puts "mov.w #{operands[0].labelref.asmLabel}, #{operands[1].sh4Operand}"
                else
                    $asm.puts "mov.l #{operands[0].labelref.asmLabel}, #{operands[1].sh4Operand}"
                end
            elsif operands[0].sh4Operand != operands[1].sh4Operand
                $asm.puts "mov #{sh4Operands(operands)}"
            end
        when "leap"
            if operands[0].is_a? BaseIndex
                biop = operands[0]
                $asm.puts "mov #{sh4Operands([biop.index, operands[1]])}"
                if biop.scaleShift > 0
                    emitSH4ShiftImm(biop.scaleShift, operands[1], "l")
                end
                $asm.puts "add #{sh4Operands([biop.base, operands[1]])}"
                if biop.offset.value != 0
                    $asm.puts "add #{sh4Operands([biop.offset, operands[1]])}"
                end
            elsif operands[0].is_a? Address
                if operands[0].base != operands[1]
                    $asm.puts "mov #{sh4Operands([operands[0].base, operands[1]])}"
                end
                if operands[0].offset.value != 0
                    $asm.puts "add #{sh4Operands([operands[0].offset, operands[1]])}"
                end
            else
                raise "Unhandled parameters for opcode #{opcode} at #{codeOriginString}"
            end
        when "ldspr"
            $asm.puts "lds #{sh4Operands(operands)}, pr"
        when "stspr"
            $asm.puts "sts pr, #{sh4Operands(operands)}"
        when "memfence"
            $asm.puts "synco"
        when "pop"
            if operands[0].sh4Operand == "pr"
                $asm.puts "lds.l @r15+, #{sh4Operands(operands)}"
            else
                $asm.puts "mov.l @r15+, #{sh4Operands(operands)}"
            end
        when "push"
            if operands[0].sh4Operand == "pr"
                $asm.puts "sts.l #{sh4Operands(operands)}, @-r15"
            else
                $asm.puts "mov.l #{sh4Operands(operands)}, @-r15"
            end
        when "break"
            # This special opcode always generates an illegal instruction exception.
            $asm.puts ".word 0xfffd"
        else
            lowerDefault
        end
    end
end