Fix fmvis & fishmv bit handling for d0, add tests for negative fp numbers

[openpower-isa.git] / src / openpower / sv / trans / svp64.py

# SPDX-License-Identifier: LGPLv3+
# Copyright (C) 2021 Luke Kenneth Casson Leighton <lkcl@lkcl.net>
# Funded by NLnet http://nlnet.nl

"""SVP64 OpenPOWER v3.0B assembly translator

This class takes raw svp64 assembly mnemonics (aliases excluded) and creates
an EXT001-encoded "svp64 prefix" (as a .long) followed by a v3.0B opcode.

It is very simple and straightforward, the only weirdness being the
extraction of the register information and conversion to v3.0B numbering.

Encoding format of svp64: https://libre-soc.org/openpower/sv/svp64/
Encoding format of arithmetic: https://libre-soc.org/openpower/sv/normal/
Encoding format of LDST: https://libre-soc.org/openpower/sv/ldst/
**TODO format of branches: https://libre-soc.org/openpower/sv/branches/**
**TODO format of CRs: https://libre-soc.org/openpower/sv/cr_ops/**
Bugtracker: https://bugs.libre-soc.org/show_bug.cgi?id=578
"""

import functools
import os
import sys
from collections import OrderedDict

from openpower.decoder.isa.caller import (SVP64PrefixFields, SV64P_MAJOR_SIZE,
                                          SV64P_PID_SIZE, SVP64RMFields,
                                          SVP64RM_EXTRA2_SPEC_SIZE,
                                          SVP64RM_EXTRA3_SPEC_SIZE,
                                          SVP64RM_MODE_SIZE,
                                          SVP64RM_SMASK_SIZE,
                                          SVP64RM_MMODE_SIZE,
                                          SVP64RM_MASK_SIZE,
                                          SVP64RM_SUBVL_SIZE,
                                          SVP64RM_EWSRC_SIZE,
                                          SVP64RM_ELWIDTH_SIZE)
from openpower.decoder.pseudo.pagereader import ISA
from openpower.decoder.power_svp64 import SVP64RM, get_regtype, decode_extra
from openpower.decoder.selectable_int import SelectableInt
from openpower.consts import SVP64MODE

# for debug logging
from openpower.util import log


def instruction(*fields):
    def instruction(insn, desc):
        (value, start, end) = desc
        bits = ((1,) * ((end + 1) - start))
        mask = 0
        for bit in bits:
            mask = ((mask << 1) | bit)
        return (insn | ((value & mask) << (31 - end)))

    return functools.reduce(instruction, fields, 0)


def setvl(fields, Rc):
    """
    setvl is a *32-bit-only* instruction. It controls SVSTATE.
    It is *not* a 64-bit-prefixed Vector instruction (no sv.setvl, yet),
    it is a Vector *control* instruction.

    * setvl RT,RA,SVi,vf,vs,ms

    1.6.28 SVL-FORM - from fields.txt
    |0     |6    |11    |16   |23 |24 |25 |26    |31 |
    | PO   |  RT |   RA | SVi |ms |vs |vf |   XO |Rc |
    """
    PO = 22
    XO = 0b11011
    # ARRRGH these are in a non-obvious order in openpower/isa/simplev.mdwn
    # compared to the SVL-Form above. sigh
    # setvl RT,RA,SVi,vf,vs,ms
    (RT, RA, SVi, vf, vs, ms) = fields
    SVi -= 1
    return instruction(
        (PO , 0 , 5 ),
        (RT , 6 , 10),
        (RA , 11, 15),
        (SVi, 16, 22),
        (ms , 23, 23),
        (vs , 24, 24),
        (vf , 25, 25),
        (XO , 26, 30),
        (Rc , 31, 31),
    )


def svstep(fields, Rc):
    """
    svstep is a 32-bit instruction. It updates SVSTATE.
    It *can* be SVP64-prefixed, to indicate that its registers
    are Vectorised.

    * svstep RT,SVi,vf

    # 1.6.28 SVL-FORM - from fields.txt
    # |0     |6    |11    |16   |23 |24 |25 |26    |31 |
    # | PO   |  RT | /    | SVi |/  |/  |vf |   XO |Rc |

    """
    PO = 22
    XO = 0b10011
    (RT, SVi, vf) = fields
    SVi -= 1
    return instruction(
        (PO , 0 , 5 ),
        (RT , 6 , 10),
        (0  , 11, 15),
        (SVi, 16, 22),
        (0  , 23, 23),
        (0  , 24, 24),
        (vf , 25, 25),
        (XO , 26, 30),
        (Rc , 31, 31),
    )


def svshape(fields):
    """
    svshape is a *32-bit-only* instruction. It updates SVSHAPE and SVSTATE.
    It is *not* a 64-bit-prefixed Vector instruction (no sv.svshape, yet),
    it is a Vector *control* instruction.

    * svshape SVxd,SVyd,SVzd,SVrm,vf

    # 1.6.33 SVM-FORM from fields.txt
    # |0     |6        |11      |16    |21    |25 |26    |31  |
    # | PO   |  SVxd   |   SVyd | SVzd | SVrm |vf |   XO      |

    """
    PO = 22
    XO = 0b011001
    (SVxd, SVyd, SVzd, SVrm, vf) = fields
    SVxd -= 1
    SVyd -= 1
    SVzd -= 1
    return instruction(
        (PO  , 0 , 5 ),
        (SVxd, 6 , 10),
        (SVyd, 11, 15),
        (SVzd, 16, 20),
        (SVrm, 21, 24),
        (vf  , 25, 25),
        (XO  , 26, 31),
    )


def svindex(fields):
    """
    svindex is a *32-bit-only* instruction. It is a convenience
    instruction that reduces instruction count for Indexed REMAP
    Mode.
    It is *not* a 64-bit-prefixed Vector instruction (no sv.svindex, yet),
    it is a Vector *control* instruction.

    1.6.28 SVI-FORM
      |0     |6    |11    |16   |21 |23|24|25|26    31|
      | PO   |  SVG|rmm   | SVd |ew |yx|mm|sk|   XO   |
    """
    # note that the dimension field one subtracted
    PO = 22
    XO = 0b101001
    (SVG, rmm, SVd, ew, yx, mm, sk) = fields
    SVd -= 1
    return instruction(
        (PO , 0 , 5 ),
        (SVG, 6 , 10),
        (rmm, 11, 15),
        (SVd, 16, 20),
        (ew , 21, 22),
        (yx , 23, 23),
        (mm , 24, 24),
        (sk , 25, 25),
        (XO , 26, 31),
    )


def svremap(fields):
    """
    this is a *32-bit-only* instruction. It updates the SVSHAPE SPR
    it is *not* a 64-bit-prefixed Vector instruction (no sv.svremap),
    it is a Vector *control* instruction.

    * svremap SVme,mi0,mi1,mi2,mo0,mo1,pst

    # 1.6.34 SVRM-FORM
       |0     |6     |11  |13   |15   |17   |19   |21  |22   |26     |31 |
       | PO   | SVme |mi0 | mi1 | mi2 | mo0 | mo1 |pst |///  | XO        |

    """
    PO = 22
    XO = 0b111001
    (SVme, mi0, mi1, mi2, mo0, mo1, pst) = fields
    return instruction(
        (PO  , 0 , 5 ),
        (SVme, 6 , 10),
        (mi0 , 11, 12),
        (mi1 , 13, 14),
        (mi2 , 15, 16),
        (mo0 , 17, 18),
        (mo1 , 19, 20),
        (pst , 21, 21),
        (0   , 22, 25),
        (XO  , 26, 31),
    )


# ok from here-on down these are added as 32-bit instructions
# and are here only because binutils (at present) doesn't have
# them (that's being fixed!)
# they can - if implementations then choose - be Vectorised
# because they are general-purpose scalar instructions
def bmask(fields):
    """
    1.6.2.2 BM2-FORM
    |0     |6    |11    |16    |21   |26 |27    31|
    | PO   |  RT |   RA |   RB |bm   |L  |   XO   |
    """
    PO = 22
    XO = 0b010001
    (RT, RA, RB, bm, L) = fields
    return instruction(
        (PO, 0 , 5 ),
        (RT, 6 , 10),
        (RA, 11, 15),
        (RB, 16, 20),
        (bm, 21, 25),
        (L , 26, 26),
        (XO, 27, 31),
    )


def fsins(fields, Rc):
    # XXX WARNING THESE ARE NOT APPROVED BY OPF ISA WG
    # however we are out of space with opcode 22
    # 1.6.7 X-FORM
    # |0     |6 |7|8|9  |10  |11|12|13  |15|16|17     |20|21    |31  |
    # | PO   |   FRT         |     ///     |   FRB       |   XO |Rc  |
    PO = 59
    XO = 0b1000001110
    (FRT, FRB) = fields
    return instruction(
        (PO , 0 , 5 ),
        (FRT, 6 , 10),
        (0  , 11, 15),
        (FRB, 16, 20),
        (XO , 21, 30),
        (Rc , 31, 31),
    )


def fcoss(fields, Rc):
    # XXX WARNING THESE ARE NOT APPROVED BY OPF ISA WG
    # however we are out of space with opcode 22
    # 1.6.7 X-FORM
    # |0     |6 |7|8|9  |10  |11|12|13  |15|16|17     |20|21    |31  |
    # | PO   |   FRT         |     ///     |   FRB       |   XO |Rc  |
    PO = 59
    XO = 0b1000101110
    (FRT, FRB) = fields
    return instruction(
        (PO , 0 , 5 ),
        (FRT, 6 , 10),
        (0  , 11, 15),
        (FRB, 16, 20),
        (XO , 21, 30),
        (Rc , 31, 31),
    )


def ternlogi(fields, Rc):
    # XXX WARNING THESE ARE NOT APPROVED BY OPF ISA WG
    # however we are out of space with opcode 22
    # 1.6.34 TLI-FORM
    #   |0   |6   |11   |16   |21   |29  |31 |
    #   | PO | RT |  RA |  RB | TLI | XO |Rc |
    PO = 5
    XO = 0
    (RT, RA, RB, TLI) = fields
    return instruction(
        (PO , 0 , 5 ),
        (RT , 6 , 10),
        (RA , 11, 15),
        (RB , 16, 20),
        (TLI, 21, 28),
        (XO , 29, 30),
        (Rc , 31, 31),
    )


def grev(fields, Rc, imm, wide):
    # XXX WARNING THESE ARE NOT APPROVED BY OPF ISA WG
    # however we are out of space with opcode 22
    insn = PO = 5
    # _ matches fields in table at:
    # https://libre-soc.org/openPOwer/sv/bitmanip/
    XO = 0b1_0010_110
    if wide:
        XO |= 0b100_000
    if imm:
        XO |= 0b1000_000
    (RT, RA, XBI) = fields
    insn = (insn << 5) | RT
    insn = (insn << 5) | RA
    if imm and not wide:
        assert 0 <= XBI < 64
        insn = (insn << 6) | XBI
        insn = (insn << 9) | XO
    else:
        assert 0 <= XBI < 32
        insn = (insn << 5) | XBI
        insn = (insn << 10) | XO
    insn = (insn << 1) | Rc
    return insn


def av(fields, XO, Rc):
    # 1.6.7 X-FORM
    #   |0     |6 |7|8|9  |10  |11|12|13  |15|16|17     |20|21    |31  |
    #   | PO   |       RT      |    RA       |    RB       |   XO |Rc  |
    PO = 22
    (RT, RA, RB) = fields
    return instruction(
        (PO, 0 , 5 ),
        (RT, 6 , 10),
        (RA, 11, 15),
        (RB, 16, 20),
        (XO, 21, 30),
        (Rc, 31, 31),
    )


def fmvis(fields):
    # XXX WARNING THESE ARE NOT APPROVED BY OPF ISA WG
    # V3.0B 1.6.6 DX-FORM
    # |0     |6 |7|8|9  |10  |11|12|13  |15|16|17     |26|27    |31  |
    # | PO   |   FRS         |     d1      |      d0  |      XO |d2  |
    PO = 22
    XO = 0b00011
    (FRS, imm) = fields
    # first split imm into d1, d0 and d2. sigh
    d2 = (imm & 1) # LSB (0)
    d1 = (imm >> 1) & 0b11111 # bits 1-5
    d0 = (imm >> 6) # MSBs 6-15
    return instruction(
        (PO , 0 , 5),
        (FRS, 6 , 10),
        (d1,  11, 15),
        (d0,  16, 25),
        (XO , 26, 30),
        (d2 , 31, 31),
    )


def fishmv(fields):
    # XXX WARNING THESE ARE NOT APPROVED BY OPF ISA WG
    # V3.0B 1.6.6 DX-FORM
    # |0     |6 |7|8|9  |10  |11|12|13  |15|16|17     |26|27   |31  |
    # | PO   |   FRS         |     d1      |      d0  |     XO |d2  |
    PO = 22
    XO = 0b01011
    (FRS, imm) = fields
    # first split imm into d1, d0 and d2. sigh
    d2 = (imm & 1) # LSB (0)
    d1 = (imm >> 1) & 0b11111 # bits 1-5
    d0 = (imm >> 6) # MSBs 6-15
    return instruction(
        (PO , 0 , 5),
        (FRS, 6 , 10),
        (d1,  11, 15),
        (d0,  16, 25),
        (XO , 26, 30),
        (d2 , 31, 31),
    )


CUSTOM_INSNS = {}
for (name, hook) in (
            ("setvl", setvl),
            ("svstep", svstep),
            ("fsins", fsins),
            ("fcoss", fcoss),
            ("ternlogi", ternlogi),
        ):
    CUSTOM_INSNS[name] = functools.partial(hook, Rc=False)
    CUSTOM_INSNS[f"{name}."] = functools.partial(hook, Rc=True)
CUSTOM_INSNS["bmask"] = bmask
CUSTOM_INSNS["svshape"] = svshape
CUSTOM_INSNS["svindex"] = svindex
CUSTOM_INSNS["svremap"] = svremap
CUSTOM_INSNS["fmvis"] = fmvis
CUSTOM_INSNS["fishmv"] = fishmv

for (name, imm, wide) in (
            ("grev", False, False),
            ("grevi", True, False),
            ("grevw", False, True),
            ("grevwi", True, True),
        ):
    CUSTOM_INSNS[name] = functools.partial(grev,
        imm=("i" in name), wide=("w" in name), Rc=False)
    CUSTOM_INSNS[f"{name}."] = functools.partial(grev,
        imm=("i" in name), wide=("w" in name), Rc=True)

for (name, XO) in (
            ("maxs"   , 0b0111001110),
            ("maxu"   , 0b0011001110),
            ("minu"   , 0b0001001110),
            ("mins"   , 0b0101001110),
            ("absdu"  , 0b1011110110),
            ("absds"  , 0b1001110110),
            ("avgadd" , 0b1101001110),
            ("absdacu", 0b1111110110),
            ("absdacs", 0b0111110110),
            ("cprop"  , 0b0110001110),
        ):
    CUSTOM_INSNS[name] = functools.partial(av, XO=XO, Rc=False)
    CUSTOM_INSNS[f"{name}."] = functools.partial(av, XO=XO, Rc=True)


# decode GPR into sv extra
def get_extra_gpr(etype, regmode, field):
    if regmode == 'scalar':
        # cut into 2-bits 5-bits SS FFFFF
        sv_extra = field >> 5
        field = field & 0b11111
    else:
        # cut into 5-bits 2-bits FFFFF SS
        sv_extra = field & 0b11
        field = field >> 2
    return sv_extra, field


# decode 3-bit CR into sv extra
def get_extra_cr_3bit(etype, regmode, field):
    if regmode == 'scalar':
        # cut into 2-bits 3-bits SS FFF
        sv_extra = field >> 3
        field = field & 0b111
    else:
        # cut into 3-bits 4-bits FFF SSSS but will cut 2 zeros off later
        sv_extra = field & 0b1111
        field = field >> 4
    return sv_extra, field


# decodes SUBVL
def decode_subvl(encoding):
    pmap = {'2': 0b01, '3': 0b10, '4': 0b11}
    assert encoding in pmap, \
        "encoding %s for SUBVL not recognised" % encoding
    return pmap[encoding]


# decodes elwidth
def decode_elwidth(encoding):
    pmap = {'8': 0b11, '16': 0b10, '32': 0b01}
    assert encoding in pmap, \
        "encoding %s for elwidth not recognised" % encoding
    return pmap[encoding]


# decodes predicate register encoding
def decode_predicate(encoding):
    pmap = {  # integer
        '1<<r3': (0, 0b001),
        'r3': (0, 0b010),
        '~r3': (0, 0b011),
        'r10': (0, 0b100),
        '~r10': (0, 0b101),
        'r30': (0, 0b110),
        '~r30': (0, 0b111),
        # CR
        'lt': (1, 0b000),
        'nl': (1, 0b001), 'ge': (1, 0b001),  # same value
        'gt': (1, 0b010),
        'ng': (1, 0b011), 'le': (1, 0b011),  # same value
        'eq': (1, 0b100),
        'ne': (1, 0b101),
        'so': (1, 0b110), 'un': (1, 0b110),  # same value
        'ns': (1, 0b111), 'nu': (1, 0b111),  # same value
    }
    assert encoding in pmap, \
        "encoding %s for predicate not recognised" % encoding
    return pmap[encoding]


# decodes "Mode" in similar way to BO field (supposed to, anyway)
def decode_bo(encoding):
    pmap = {  # TODO: double-check that these are the same as Branch BO
        'lt': 0b000,
        'nl': 0b001, 'ge': 0b001,  # same value
        'gt': 0b010,
        'ng': 0b011, 'le': 0b011,  # same value
        'eq': 0b100,
        'ne': 0b101,
        'so': 0b110, 'un': 0b110,  # same value
        'ns': 0b111, 'nu': 0b111,  # same value
    }
    assert encoding in pmap, \
        "encoding %s for BO Mode not recognised" % encoding
    return pmap[encoding]

# partial-decode fail-first mode


def decode_ffirst(encoding):
    if encoding in ['RC1', '~RC1']:
        return encoding
    return decode_bo(encoding)


def decode_reg(field, macros=None):
    if macros is None:
        macros = {}
    # decode the field number. "5.v" or "3.s" or "9"
    # and now also "*0", and "*%0".  note: *NOT* to add "*%rNNN" etc.
    # https://bugs.libre-soc.org/show_bug.cgi?id=884#c0
    if field.startswith(("*%", "*")):
        if field.startswith("*%"):
            field = field[2:]
        else:
            field = field[1:]
        while field in macros:
            field = macros[field]
        return int(field), "vector"  # actual register number

    # try old convention (to be retired)
    field = field.split(".")
    regmode = 'scalar'  # default
    if len(field) == 2:
        if field[1] == 's':
            regmode = 'scalar'
        elif field[1] == 'v':
            regmode = 'vector'
    field = int(field[0])  # actual register number
    return field, regmode


def decode_imm(field):
    ldst_imm = "(" in field and field[-1] == ')'
    if ldst_imm:
        return field[:-1].split("(")
    else:
        return None, field


def crf_extra(etype, regmode, field, extras):
    """takes a CR Field number (CR0-CR127), splits into EXTRA2/3 and v3.0
    the scalar/vector mode (crNN.v or crNN.s) changes both the format
    of the EXTRA2/3 encoding as well as what range of registers is possible.
    this function can be used for both BF/BFA and BA/BB/BT by first removing
    the bottom 2 bits of BA/BB/BT then re-instating them after encoding.
    see https://libre-soc.org/openpower/sv/svp64/appendix/#cr_extra
    for specification
    """
    sv_extra, field = get_extra_cr_3bit(etype, regmode, field)
    # now sanity-check (and shrink afterwards)
    if etype == 'EXTRA2':
        # 3-bit CR Field (BF, BFA) EXTRA2 encoding
        if regmode == 'scalar':
            # range is CR0-CR15 in increments of 1
            assert (sv_extra >> 1) == 0, \
                "scalar CR %s cannot fit into EXTRA2 %s" % \
                (rname, str(extras[extra_idx]))
            # all good: encode as scalar
            sv_extra = sv_extra & 0b01
        else: # vector
            # range is CR0-CR127 in increments of 16
            assert sv_extra & 0b111 == 0, \
                "vector CR %s cannot fit into EXTRA2 %s" % \
                (rname, str(extras[extra_idx]))
            # all good: encode as vector (bit 2 set)
            sv_extra = 0b10 | (sv_extra >> 3)
    else:
        # 3-bit CR Field (BF, BFA) EXTRA3 encoding
        if regmode == 'scalar':
            # range is CR0-CR31 in increments of 1
            assert (sv_extra >> 2) == 0, \
                "scalar CR %s cannot fit into EXTRA3 %s" % \
                (rname, str(extras[extra_idx]))
            # all good: encode as scalar
            sv_extra = sv_extra & 0b11
        else: # vector
            # range is CR0-CR127 in increments of 8
            assert sv_extra & 0b11 == 0, \
                "vector CR %s cannot fit into EXTRA3 %s" % \
                (rname, str(extras[extra_idx]))
            # all good: encode as vector (bit 3 set)
            sv_extra = 0b100 | (sv_extra >> 2)
    return sv_extra, field


def to_number(field):
    if field.startswith("0x"):
        return eval(field)
    if field.startswith("0b"):
        return eval(field)
    return int(field)


# decodes svp64 assembly listings and creates EXT001 svp64 prefixes
class SVP64Asm:
    def __init__(self, lst, bigendian=False, macros=None):
        if macros is None:
            macros = {}
        self.macros = macros
        self.lst = lst
        self.trans = self.translate(lst)
        self.isa = ISA()  # reads the v3.0B pseudo-code markdown files
        self.svp64 = SVP64RM()  # reads the svp64 Remap entries for registers
        assert bigendian == False, "error, bigendian not supported yet"

    def __iter__(self):
        yield from self.trans

    def translate_one(self, insn, macros=None):
        if macros is None:
            macros = {}
        macros.update(self.macros)
        isa = self.isa
        svp64 = self.svp64
        # find first space, to get opcode
        ls = insn.split(' ')
        opcode = ls[0]
        # now find opcode fields
        fields = ''.join(ls[1:]).split(',')
        mfields = list(map(str.strip, fields))
        log("opcode, fields", ls, opcode, mfields)
        fields = []
        # macro substitution
        for field in mfields:
            fields.append(macro_subst(macros, field))
        log("opcode, fields substed", ls, opcode, fields)

        # identify if it is a special instruction
        custom_insn_hook = CUSTOM_INSNS.get(opcode)
        if custom_insn_hook is not None:
            fields = tuple(map(to_number, fields))
            insn = custom_insn_hook(fields)
            log(opcode, bin(insn))
            yield ".long 0x%x" % insn
            return

        # identify if is a svp64 mnemonic
        if not opcode.startswith('sv.'):
            yield insn  # unaltered
            return
        opcode = opcode[3:]  # strip leading "sv"

        # start working on decoding the svp64 op: sv.basev30Bop/vec2/mode
        opmodes = opcode.split("/")  # split at "/"
        v30b_op = opmodes.pop(0)    # first is the v3.0B
        # check instruction ends with dot
        rc_mode = v30b_op.endswith('.')
        if rc_mode:
            v30b_op = v30b_op[:-1]

        # sigh again, have to recognised LD/ST bit-reverse instructions
        # this has to be "processed" to fit into a v3.0B without the "sh"
        # e.g. ldsh is actually ld
        ldst_shift = v30b_op.startswith("l") and v30b_op.endswith("sh")

        if v30b_op not in isa.instr:
            raise Exception("opcode %s of '%s' not supported" %
                            (v30b_op, insn))

        if ldst_shift:
            # okaay we need to process the fields and make this:
            #     ldsh RT, SVD(RA), RC  - 11 bits for SVD, 5 for RC
            # into this:
            #     ld RT, D(RA)          - 16 bits
            # likewise same for SVDS (9 bits for SVDS, 5 for RC, 14 bits for DS)
            form = isa.instr[v30b_op].form  # get form (SVD-Form, SVDS-Form)

            newfields = []
            for field in fields:
                # identify if this is a ld/st immediate(reg) thing
                ldst_imm = "(" in field and field[-1] == ')'
                if ldst_imm:
                    newfields.append(field[:-1].split("("))
                else:
                    newfields.append(field)

            immed, RA = newfields[1]
            immed = int(immed)
            RC = int(newfields.pop(2))  # better be an integer number!
            if form == 'SVD':  # 16 bit: immed 11 bits, RC shift up 11
                immed = (immed & 0b11111111111) | (RC << 11)
                if immed & (1 << 15):  # should be negative
                    immed -= 1 << 16
            if form == 'SVDS':  # 14 bit: immed 9 bits, RC shift up 9
                immed = (immed & 0b111111111) | (RC << 9)
                if immed & (1 << 13):  # should be negative
                    immed -= 1 << 14
            newfields[1] = "%d(%s)" % (immed, RA)
            fields = newfields

            # and strip off "sh" from end, and add "sh" to opmodes, instead
            v30b_op = v30b_op[:-2]
            opmodes.append("sh")
            log("rewritten", v30b_op, opmodes, fields)

        if v30b_op not in svp64.instrs:
            raise Exception("opcode %s of '%s' not an svp64 instruction" %
                            (v30b_op, insn))
        v30b_regs = isa.instr[v30b_op].regs[0]  # get regs info "RT, RA, RB"
        rm = svp64.instrs[v30b_op]             # one row of the svp64 RM CSV
        log("v3.0B op", v30b_op, "Rc=1" if rc_mode else '')
        log("v3.0B regs", opcode, v30b_regs)
        log("RM", rm)

        # right.  the first thing to do is identify the ordering of
        # the registers, by name.  the EXTRA2/3 ordering is in
        # rm['0']..rm['3'] but those fields contain the names RA, BB
        # etc.  we have to read the pseudocode to understand which
        # reg is which in our instruction. sigh.

        # first turn the svp64 rm into a "by name" dict, recording
        # which position in the RM EXTRA it goes into
        # also: record if the src or dest was a CR, for sanity-checking
        # (elwidth overrides on CRs are banned)
        decode = decode_extra(rm)
        dest_reg_cr, src_reg_cr, svp64_src, svp64_dest = decode

        log("EXTRA field index, src", svp64_src)
        log("EXTRA field index, dest", svp64_dest)

        # okaaay now we identify the field value (opcode N,N,N) with
        # the pseudo-code info (opcode RT, RA, RB)
        assert len(fields) == len(v30b_regs), \
            "length of fields %s must match insn `%s` fields %s" % \
            (str(v30b_regs), insn, str(fields))
        opregfields = zip(fields, v30b_regs)  # err that was easy

        # now for each of those find its place in the EXTRA encoding
        # note there is the possibility (for LD/ST-with-update) of
        # RA occurring **TWICE**.  to avoid it getting added to the
        # v3.0B suffix twice, we spot it as a duplicate, here
        extras = OrderedDict()
        for idx, (field, regname) in enumerate(opregfields):
            imm, regname = decode_imm(regname)
            rtype = get_regtype(regname)
            log("    idx find", rtype, idx, field, regname, imm)
            if rtype is None:
                # probably an immediate field, append it straight
                extras[('imm', idx, False)] = (idx, field, None, None, None)
                continue
            extra = svp64_src.get(regname, None)
            if extra is not None:
                extra = ('s', extra, False)  # not a duplicate
                extras[extra] = (idx, field, regname, rtype, imm)
                log("    idx src", idx, extra, extras[extra])
            dextra = svp64_dest.get(regname, None)
            log("regname in", regname, dextra)
            if dextra is not None:
                is_a_duplicate = extra is not None  # duplicate spotted
                dextra = ('d', dextra, is_a_duplicate)
                extras[dextra] = (idx, field, regname, rtype, imm)
                log("    idx dst", idx, extra, extras[dextra])

        # great! got the extra fields in their associated positions:
        # also we know the register type. now to create the EXTRA encodings
        etype = rm['Etype']  # Extra type: EXTRA3/EXTRA2
        ptype = rm['Ptype']  # Predication type: Twin / Single
        extra_bits = 0
        v30b_newfields = []
        for extra_idx, (idx, field, rname, rtype, iname) in extras.items():
            # is it a field we don't alter/examine?  if so just put it
            # into newfields
            if rtype is None:
                v30b_newfields.append(field)
                continue

            # identify if this is a ld/st immediate(reg) thing
            ldst_imm = "(" in field and field[-1] == ')'
            if ldst_imm:
                immed, field = field[:-1].split("(")

            field, regmode = decode_reg(field, macros=macros)
            log("    ", extra_idx, rname, rtype,
                regmode, iname, field, end=" ")

            # see Mode field https://libre-soc.org/openpower/sv/svp64/
            # XXX TODO: the following is a bit of a laborious repeated
            # mess, which could (and should) easily be parameterised.
            # XXX also TODO: the LD/ST modes which are different
            # https://libre-soc.org/openpower/sv/ldst/

            # rright.  SVP64 register numbering is from 0 to 127
            # for GPRs, FPRs *and* CR Fields, where for v3.0 the GPRs and RPFs
            # are 0-31 and CR Fields are only 0-7.  the SVP64 RM "Extra"
            # area is used to extend the numbering from the 32-bit
            # instruction, and also to record whether the register
            # is scalar or vector. on a per-operand basis.  this
            # results in a slightly finnicky encoding: here we go...

            # encode SV-GPR and SV-FPR field into extra, v3.0field
            if rtype in ['GPR', 'FPR']:
                sv_extra, field = get_extra_gpr(etype, regmode, field)
                # now sanity-check. EXTRA3 is ok, EXTRA2 has limits
                # (and shrink to a single bit if ok)
                if etype == 'EXTRA2':
                    if regmode == 'scalar':
                        # range is r0-r63 in increments of 1
                        assert (sv_extra >> 1) == 0, \
                            "scalar GPR %s cannot fit into EXTRA2 %s" % \
                            (rname, str(extras[extra_idx]))
                        # all good: encode as scalar
                        sv_extra = sv_extra & 0b01
                    else:
                        # range is r0-r127 in increments of 2 (r0 r2 ... r126)
                        assert sv_extra & 0b01 == 0, \
                            "%s: vector field %s cannot fit " \
                            "into EXTRA2 %s" % \
                            (insn, rname, str(extras[extra_idx]))
                        # all good: encode as vector (bit 2 set)
                        sv_extra = 0b10 | (sv_extra >> 1)
                elif regmode == 'vector':
                    # EXTRA3 vector bit needs marking
                    sv_extra |= 0b100

            # encode SV-CR 3-bit field into extra, v3.0field.
            # 3-bit is for things like BF and BFA
            elif rtype == 'CR_3bit':
                sv_extra, field =  crf_extra(etype, regmode, field, extras)

            # encode SV-CR 5-bit field into extra, v3.0field
            # 5-bit is for things like BA BB BC BT etc.
            # *sigh* this is the same as 3-bit except the 2 LSBs of the
            # 5-bit field are passed through unaltered.
            elif rtype == 'CR_5bit':
                cr_subfield = field & 0b11 # record bottom 2 bits for later
                field = field >> 2         # strip bottom 2 bits
                # use the exact same 3-bit function for the top 3 bits
                sv_extra, field =  crf_extra(etype, regmode, field, extras)
                # reconstruct the actual 5-bit CR field (preserving the
                # bottom 2 bits, unaltered)
                field = (field << 2) | cr_subfield

            else:
                raise Exception("no type match: %s" % rtype)

            # capture the extra field info
            log("=>", "%5s" % bin(sv_extra), field)
            extras[extra_idx] = sv_extra

            # append altered field value to v3.0b, differs for LDST
            # note that duplicates are skipped e.g. EXTRA2 contains
            # *BOTH* s:RA *AND* d:RA which happens on LD/ST-with-update
            srcdest, idx, duplicate = extra_idx
            if duplicate:  # skip adding to v3.0b fields, already added
                continue
            if ldst_imm:
                v30b_newfields.append(("%s(%s)" % (immed, str(field))))
            else:
                v30b_newfields.append(str(field))

        log("new v3.0B fields", v30b_op, v30b_newfields)
        log("extras", extras)

        # rright.  now we have all the info. start creating SVP64 RM
        svp64_rm = SVP64RMFields()

        # begin with EXTRA fields
        for idx, sv_extra in extras.items():
            log(idx)
            if idx is None:
                continue
            if idx[0] == 'imm':
                continue
            srcdest, idx, duplicate = idx
            if etype == 'EXTRA2':
                svp64_rm.extra2[idx].eq(
                    SelectableInt(sv_extra, SVP64RM_EXTRA2_SPEC_SIZE))
            else:
                svp64_rm.extra3[idx].eq(
                    SelectableInt(sv_extra, SVP64RM_EXTRA3_SPEC_SIZE))

        # identify if the op is a LD/ST. the "blegh" way. copied
        # from power_enums.  TODO, split the list _insns down.
        is_ld = v30b_op in [
            "lbarx", "lbz", "lbzu", "lbzux", "lbzx",            # load byte
            "ld", "ldarx", "ldbrx", "ldu", "ldux", "ldx",       # load double
            "lfs", "lfsx", "lfsu", "lfsux",                     # FP load single
            "lfd", "lfdx", "lfdu", "lfdux", "lfiwzx", "lfiwax",  # FP load dbl
            "lha", "lharx", "lhau", "lhaux", "lhax",            # load half
            "lhbrx", "lhz", "lhzu", "lhzux", "lhzx",            # more load half
            "lwa", "lwarx", "lwaux", "lwax", "lwbrx",           # load word
            "lwz", "lwzcix", "lwzu", "lwzux", "lwzx",           # more load word
        ]
        is_st = v30b_op in [
            "stb", "stbcix", "stbcx", "stbu", "stbux", "stbx",
            "std", "stdbrx", "stdcx", "stdu", "stdux", "stdx",
            "stfs", "stfsx", "stfsu", "stfux",                  # FP store sgl
            "stfd", "stfdx", "stfdu", "stfdux", "stfiwx",       # FP store dbl
            "sth", "sthbrx", "sthcx", "sthu", "sthux", "sthx",
            "stw", "stwbrx", "stwcx", "stwu", "stwux", "stwx",
        ]
        # use this to determine if the SVP64 RM format is different.
        # see https://libre-soc.org/openpower/sv/ldst/
        is_ldst = is_ld or is_st

        # branch-conditional detection
        is_bc = v30b_op in [
            "bc", "bclr",
        ]

        # parts of svp64_rm
        mmode = 0  # bit 0
        pmask = 0  # bits 1-3
        destwid = 0  # bits 4-5
        srcwid = 0  # bits 6-7
        subvl = 0   # bits 8-9
        smask = 0  # bits 16-18 but only for twin-predication
        mode = 0  # bits 19-23

        mask_m_specified = False
        has_pmask = False
        has_smask = False

        saturation = None
        src_zero = 0
        dst_zero = 0
        sv_mode = None

        mapreduce = False
        reverse_gear = False
        mapreduce_crm = False
        mapreduce_svm = False

        predresult = False
        failfirst = False
        ldst_elstride = 0

        # branch-conditional bits
        bc_all = 0
        bc_lru = 0
        bc_brc = 0
        bc_svstep = 0
        bc_vsb = 0
        bc_vlset = 0
        bc_vli = 0
        bc_snz = 0

        # ok let's start identifying opcode augmentation fields
        for encmode in opmodes:
            # predicate mask (src and dest)
            if encmode.startswith("m="):
                pme = encmode
                pmmode, pmask = decode_predicate(encmode[2:])
                smmode, smask = pmmode, pmask
                mmode = pmmode
                mask_m_specified = True
            # predicate mask (dest)
            elif encmode.startswith("dm="):
                pme = encmode
                pmmode, pmask = decode_predicate(encmode[3:])
                mmode = pmmode
                has_pmask = True
            # predicate mask (src, twin-pred)
            elif encmode.startswith("sm="):
                sme = encmode
                smmode, smask = decode_predicate(encmode[3:])
                mmode = smmode
                has_smask = True
            # shifted LD/ST
            elif encmode.startswith("sh"):
                ldst_shift = True
            # vec2/3/4
            elif encmode.startswith("vec"):
                subvl = decode_subvl(encmode[3:])
            # elwidth
            elif encmode.startswith("ew="):
                destwid = decode_elwidth(encmode[3:])
            elif encmode.startswith("sw="):
                srcwid = decode_elwidth(encmode[3:])
            # element-strided LD/ST
            elif encmode == 'els':
                ldst_elstride = 1
            # saturation
            elif encmode == 'sats':
                assert sv_mode is None
                saturation = 1
                sv_mode = 0b10
            elif encmode == 'satu':
                assert sv_mode is None
                sv_mode = 0b10
                saturation = 0
            # predicate zeroing
            elif encmode == 'sz':
                src_zero = 1
            elif encmode == 'dz':
                dst_zero = 1
            # failfirst
            elif encmode.startswith("ff="):
                assert sv_mode is None
                sv_mode = 0b01
                failfirst = decode_ffirst(encmode[3:])
            # predicate-result, interestingly same as fail-first
            elif encmode.startswith("pr="):
                assert sv_mode is None
                sv_mode = 0b11
                predresult = decode_ffirst(encmode[3:])
            # map-reduce mode, reverse-gear
            elif encmode == 'mrr':
                assert sv_mode is None
                sv_mode = 0b00
                mapreduce = True
                reverse_gear = True
            # map-reduce mode
            elif encmode == 'mr':
                assert sv_mode is None
                sv_mode = 0b00
                mapreduce = True
            elif encmode == 'crm':  # CR on map-reduce
                assert sv_mode is None
                sv_mode = 0b00
                mapreduce_crm = True
            elif encmode == 'svm':  # sub-vector mode
                mapreduce_svm = True
            elif is_bc:
                if encmode == 'all':
                    bc_all = 1
                elif encmode == 'st':  # svstep mode
                    bc_step = 1
                elif encmode == 'sr':  # svstep BRc mode
                    bc_step = 1
                    bc_brc = 1
                elif encmode == 'vs':  # VLSET mode
                    bc_vlset = 1
                elif encmode == 'vsi':  # VLSET mode with VLI (VL inclusives)
                    bc_vlset = 1
                    bc_vli = 1
                elif encmode == 'vsb':  # VLSET mode with VSb
                    bc_vlset = 1
                    bc_vsb = 1
                elif encmode == 'vsbi':  # VLSET mode with VLI and VSb
                    bc_vlset = 1
                    bc_vli = 1
                    bc_vsb = 1
                elif encmode == 'snz':  # sz (only) already set above
                    src_zero = 1
                    bc_snz = 1
                elif encmode == 'lu':  # LR update mode
                    bc_lru = 1
                else:
                    raise AssertionError("unknown encmode %s" % encmode)
            else:
                raise AssertionError("unknown encmode %s" % encmode)

        if ptype == '2P':
            # since m=xx takes precedence (overrides) sm=xx and dm=xx,
            # treat them as mutually exclusive
            if mask_m_specified:
                assert not has_smask,\
                    "cannot have both source-mask and predicate mask"
                assert not has_pmask,\
                    "cannot have both dest-mask and predicate mask"
            # since the default is INT predication (ALWAYS), if you
            # specify one CR mask, you must specify both, to avoid
            # mixing INT and CR reg types
            if has_pmask and pmmode == 1:
                assert has_smask, \
                    "need explicit source-mask in CR twin predication"
            if has_smask and smmode == 1:
                assert has_pmask, \
                    "need explicit dest-mask in CR twin predication"
            # sanity-check that 2Pred mask is same mode
            if has_pmask and has_smask:
                assert smmode == pmmode, \
                    "predicate masks %s and %s must be same reg type" % \
                    (pme, sme)

        # sanity-check that twin-predication mask only specified in 2P mode
        if ptype == '1P':
            assert not has_smask, \
                "source-mask can only be specified on Twin-predicate ops"
            assert not has_pmask, \
                "dest-mask can only be specified on Twin-predicate ops"

        # construct the mode field, doing sanity-checking along the way
        if mapreduce_svm:
            assert sv_mode == 0b00, "sub-vector mode in mapreduce only"
            assert subvl != 0, "sub-vector mode not possible on SUBVL=1"

        if src_zero:
            assert has_smask or mask_m_specified, \
                "src zeroing requires a source predicate"
        if dst_zero:
            assert has_pmask or mask_m_specified, \
                "dest zeroing requires a dest predicate"

        # check LDST shifted, only available in "normal" mode
        if is_ldst and ldst_shift:
            assert sv_mode is None, \
                "LD shift cannot have modes (%s) applied" % sv_mode

        # okaaay, so there are 4 different modes, here, which will be
        # partly-merged-in: is_ldst is merged in with "normal", but
        # is_bc is so different it's done separately.  likewise is_cr
        # (when it is done).  here are the maps:

        # for "normal" arithmetic: https://libre-soc.org/openpower/sv/normal/
        """
            | 0-1 |  2  |  3   4  |  description              |
            | --- | --- |---------|-------------------------- |
            | 00  |   0 |  dz  sz | normal mode                      |
            | 00  |   1 | 0  RG   | scalar reduce mode (mapreduce), SUBVL=1 |
            | 00  |   1 | 1  /    | parallel reduce mode (mapreduce), SUBVL=1 |
            | 00  |   1 | SVM RG  | subvector reduce mode, SUBVL>1   |
            | 01  | inv | CR-bit  | Rc=1: ffirst CR sel              |
            | 01  | inv | VLi RC1 |  Rc=0: ffirst z/nonz |
            | 10  |   N | dz   sz |  sat mode: N=0/1 u/s |
            | 11  | inv | CR-bit  |  Rc=1: pred-result CR sel |
            | 11  | inv | dz  RC1 |  Rc=0: pred-result z/nonz |
        """

        # https://libre-soc.org/openpower/sv/ldst/
        # for LD/ST-immediate:
        """
            | 0-1 |  2  |  3   4  |  description               |
            | --- | --- |---------|--------------------------- |
            | 00  | 0   |  dz els | normal mode                |
            | 00  | 1   |  dz shf | shift mode                 |
            | 01  | inv | CR-bit  | Rc=1: ffirst CR sel        |
            | 01  | inv | els RC1 |  Rc=0: ffirst z/nonz       |
            | 10  |   N | dz  els |  sat mode: N=0/1 u/s       |
            | 11  | inv | CR-bit  |  Rc=1: pred-result CR sel  |
            | 11  | inv | els RC1 |  Rc=0: pred-result z/nonz  |
        """

        # for LD/ST-indexed (RA+RB):
        """
            | 0-1 |  2  |  3   4  |  description              |
            | --- | --- |---------|-------------------------- |
            | 00  | SEA |  dz  sz | normal mode        |
            | 01  | SEA | dz sz  | Strided (scalar only source)   |
            | 10  |   N | dz   sz |  sat mode: N=0/1 u/s |
            | 11  | inv | CR-bit  |  Rc=1: pred-result CR sel |
            | 11  | inv | dz  RC1 |  Rc=0: pred-result z/nonz |
        """

        # and leaving out branches and cr_ops for now because they're
        # under development
        """ TODO branches and cr_ops
        """

        # now create mode and (overridden) src/dst widths
        # XXX TODO: sanity-check bc modes
        if is_bc:
            sv_mode = ((bc_svstep << SVP64MODE.MOD2_MSB) |
                       (bc_vlset << SVP64MODE.MOD2_LSB) |
                       (bc_snz << SVP64MODE.BC_SNZ))
            srcwid = (bc_vsb << 1) | bc_lru
            destwid = (bc_lru << 1) | bc_all

        else:

            ######################################
            # "normal" mode
            if sv_mode is None:
                mode |= src_zero << SVP64MODE.SZ  # predicate zeroing
                mode |= dst_zero << SVP64MODE.DZ  # predicate zeroing
                if is_ldst:
                    # TODO: for now, LD/ST-indexed is ignored.
                    mode |= ldst_elstride << SVP64MODE.ELS_NORMAL  # el-strided
                    # shifted mode
                    if ldst_shift:
                        mode |= 1 << SVP64MODE.LDST_SHIFT
                else:
                    # TODO, reduce and subvector mode
                    # 00  1   dz CRM  reduce mode (mapreduce), SUBVL=1
                    # 00  1   SVM CRM subvector reduce mode, SUBVL>1
                    pass
                sv_mode = 0b00

            ######################################
            # "mapreduce" modes
            elif sv_mode == 0b00:
                mode |= (0b1 << SVP64MODE.REDUCE)  # sets mapreduce
                assert dst_zero == 0, "dest-zero not allowed in mapreduce mode"
                if reverse_gear:
                    mode |= (0b1 << SVP64MODE.RG)  # sets Reverse-gear mode
                if mapreduce_crm:
                    mode |= (0b1 << SVP64MODE.CRM)  # sets CRM mode
                    assert rc_mode, "CRM only allowed when Rc=1"
                # bit of weird encoding to jam zero-pred or SVM mode in.
                # SVM mode can be enabled only when SUBVL=2/3/4 (vec2/3/4)
                if subvl == 0:
                    mode |= dst_zero << SVP64MODE.DZ  # predicate zeroing
                elif mapreduce_svm:
                    mode |= (0b1 << SVP64MODE.SVM)  # sets SVM mode

            ######################################
            # "failfirst" modes
            elif sv_mode == 0b01:
                assert src_zero == 0, "dest-zero not allowed in failfirst mode"
                if failfirst == 'RC1':
                    mode |= (0b1 << SVP64MODE.RC1)  # sets RC1 mode
                    mode |= (dst_zero << SVP64MODE.DZ)  # predicate dst-zeroing
                    assert rc_mode == False, "ffirst RC1 only ok when Rc=0"
                elif failfirst == '~RC1':
                    mode |= (0b1 << SVP64MODE.RC1)  # sets RC1 mode
                    mode |= (dst_zero << SVP64MODE.DZ)  # predicate dst-zeroing
                    mode |= (0b1 << SVP64MODE.INV)  # ... with inversion
                    assert rc_mode == False, "ffirst RC1 only ok when Rc=0"
                else:
                    assert dst_zero == 0, "dst-zero not allowed in ffirst BO"
                    assert rc_mode, "ffirst BO only possible when Rc=1"
                    mode |= (failfirst << SVP64MODE.BO_LSB)  # set BO

            ######################################
            # "saturation" modes
            elif sv_mode == 0b10:
                mode |= src_zero << SVP64MODE.SZ  # predicate zeroing
                mode |= dst_zero << SVP64MODE.DZ  # predicate zeroing
                mode |= (saturation << SVP64MODE.N)  # signed/us saturation

            ######################################
            # "predicate-result" modes.  err... code-duplication from ffirst
            elif sv_mode == 0b11:
                assert src_zero == 0, "dest-zero not allowed in predresult mode"
                if predresult == 'RC1':
                    mode |= (0b1 << SVP64MODE.RC1)  # sets RC1 mode
                    mode |= (dst_zero << SVP64MODE.DZ)  # predicate dst-zeroing
                    assert rc_mode == False, "pr-mode RC1 only ok when Rc=0"
                elif predresult == '~RC1':
                    mode |= (0b1 << SVP64MODE.RC1)  # sets RC1 mode
                    mode |= (dst_zero << SVP64MODE.DZ)  # predicate dst-zeroing
                    mode |= (0b1 << SVP64MODE.INV)  # ... with inversion
                    assert rc_mode == False, "pr-mode RC1 only ok when Rc=0"
                else:
                    assert dst_zero == 0, "dst-zero not allowed in pr-mode BO"
                    assert rc_mode, "pr-mode BO only possible when Rc=1"
                    mode |= (predresult << SVP64MODE.BO_LSB)  # set BO

        # whewww.... modes all done :)
        # now put into svp64_rm
        mode |= sv_mode
        # mode: bits 19-23
        svp64_rm.mode.eq(SelectableInt(mode, SVP64RM_MODE_SIZE))

        # put in predicate masks into svp64_rm
        if ptype == '2P':
            # source pred: bits 16-18
            svp64_rm.smask.eq(SelectableInt(smask, SVP64RM_SMASK_SIZE))
        # mask mode: bit 0
        svp64_rm.mmode.eq(SelectableInt(mmode, SVP64RM_MMODE_SIZE))
        # 1-pred: bits 1-3
        svp64_rm.mask.eq(SelectableInt(pmask, SVP64RM_MASK_SIZE))

        # and subvl: bits 8-9
        svp64_rm.subvl.eq(SelectableInt(subvl, SVP64RM_SUBVL_SIZE))

        # put in elwidths
        # srcwid: bits 6-7
        svp64_rm.ewsrc.eq(SelectableInt(srcwid, SVP64RM_EWSRC_SIZE))
        # destwid: bits 4-5
        svp64_rm.elwidth.eq(SelectableInt(destwid, SVP64RM_ELWIDTH_SIZE))

        # nice debug printout. (and now for something completely different)
        # https://youtu.be/u0WOIwlXE9g?t=146
        svp64_rm_value = svp64_rm.spr.value
        log("svp64_rm", hex(svp64_rm_value), bin(svp64_rm_value))
        log("    mmode  0    :", bin(mmode))
        log("    pmask  1-3  :", bin(pmask))
        log("    dstwid 4-5  :", bin(destwid))
        log("    srcwid 6-7  :", bin(srcwid))
        log("    subvl  8-9  :", bin(subvl))
        log("    mode   19-23:", bin(mode))
        offs = 2 if etype == 'EXTRA2' else 3  # 2 or 3 bits
        for idx, sv_extra in extras.items():
            if idx is None:
                continue
            if idx[0] == 'imm':
                continue
            srcdest, idx, duplicate = idx
            start = (10+idx*offs)
            end = start + offs-1
            log("    extra%d %2d-%2d:" % (idx, start, end),
                bin(sv_extra))
        if ptype == '2P':
            log("    smask  16-17:", bin(smask))
        log()

        # first, construct the prefix from its subfields
        svp64_prefix = SVP64PrefixFields()
        svp64_prefix.major.eq(SelectableInt(0x1, SV64P_MAJOR_SIZE))
        svp64_prefix.pid.eq(SelectableInt(0b11, SV64P_PID_SIZE))
        svp64_prefix.rm.eq(svp64_rm.spr)

        # fiinally yield the svp64 prefix and the thingy.  v3.0b opcode
        rc = '.' if rc_mode else ''
        yield ".long 0x%08x" % svp64_prefix.insn.value
        log(v30b_op, v30b_newfields)
        # argh, sv.fmadds etc. need to be done manually
        if v30b_op == 'ffmadds':
            opcode = 59 << (32-6)    # bits 0..6 (MSB0)
            opcode |= int(v30b_newfields[0]) << (32-11)  # FRT
            opcode |= int(v30b_newfields[1]) << (32-16)  # FRA
            opcode |= int(v30b_newfields[2]) << (32-21)  # FRB
            opcode |= int(v30b_newfields[3]) << (32-26)  # FRC
            opcode |= 0b00101 << (32-31)   # bits 26-30
            if rc:
                opcode |= 1  # Rc, bit 31.
            yield ".long 0x%x" % opcode
        # argh, sv.fdmadds need to be done manually
        elif v30b_op == 'fdmadds':
            opcode = 59 << (32-6)    # bits 0..6 (MSB0)
            opcode |= int(v30b_newfields[0]) << (32-11)  # FRT
            opcode |= int(v30b_newfields[1]) << (32-16)  # FRA
            opcode |= int(v30b_newfields[2]) << (32-21)  # FRB
            opcode |= int(v30b_newfields[3]) << (32-26)  # FRC
            opcode |= 0b01111 << (32-31)   # bits 26-30
            if rc:
                opcode |= 1  # Rc, bit 31.
            yield ".long 0x%x" % opcode
        # argh, sv.ffadds etc. need to be done manually
        elif v30b_op == 'ffadds':
            opcode = 59 << (32-6)    # bits 0..6 (MSB0)
            opcode |= int(v30b_newfields[0]) << (32-11)  # FRT
            opcode |= int(v30b_newfields[1]) << (32-16)  # FRA
            opcode |= int(v30b_newfields[2]) << (32-21)  # FRB
            opcode |= 0b01101 << (32-31)   # bits 26-30
            if rc:
                opcode |= 1  # Rc, bit 31.
            yield ".long 0x%x" % opcode
        # sigh have to do svstep here manually for now...
        elif v30b_op in ["svstep", "svstep."]:
            insn = 22 << (31-5)          # opcode 22, bits 0-5
            insn |= int(v30b_newfields[0]) << (31-10)  # RT       , bits 6-10
            insn |= int(v30b_newfields[1]) << (31-22)  # SVi      , bits 16-22
            insn |= int(v30b_newfields[2]) << (31-25)  # vf       , bit  25
            insn |= 0b10011 << (31-30)  # XO       , bits 26..30
            if opcode == 'svstep.':
                insn |= 1 << (31-31)     # Rc=1     , bit 31
            log("svstep", bin(insn))
            yield ".long 0x%x" % insn
        # argh, sv.fcoss etc. need to be done manually
        elif v30b_op in ["fcoss", "fcoss."]:
            insn = 59 << (31-5)  # opcode 59, bits 0-5
            insn |= int(v30b_newfields[0]) << (31-10)  # RT       , bits 6-10
            insn |= int(v30b_newfields[1]) << (31-20)  # RB       , bits 16-20
            insn |= 0b1000101110 << (31-30)  # XO       , bits 21..30
            if opcode == 'fcoss.':
                insn |= 1 << (31-31)     # Rc=1     , bit 31
            log("fcoss", bin(insn))
            yield ".long 0x%x" % insn
        else:
            yield "%s %s" % (v30b_op+rc, ", ".join(v30b_newfields))
        log("new v3.0B fields", v30b_op, v30b_newfields)

    def translate(self, lst):
        for insn in lst:
            yield from self.translate_one(insn)


def macro_subst(macros, txt):
    again = True
    log("subst", txt, macros)
    while again:
        again = False
        for macro, value in macros.items():
            if macro == txt:
                again = True
                replaced = txt.replace(macro, value)
                log("macro", txt, "replaced", replaced, macro, value)
                txt = replaced
                continue
            toreplace = '%s.s' % macro
            if toreplace == txt:
                again = True
                replaced = txt.replace(toreplace, "%s.s" % value)
                log("macro", txt, "replaced", replaced, toreplace, value)
                txt = replaced
                continue
            toreplace = '%s.v' % macro
            if toreplace == txt:
                again = True
                replaced = txt.replace(toreplace, "%s.v" % value)
                log("macro", txt, "replaced", replaced, toreplace, value)
                txt = replaced
                continue
            toreplace = '(%s)' % macro
            if toreplace in txt:
                again = True
                replaced = txt.replace(toreplace, '(%s)' % value)
                log("macro", txt, "replaced", replaced, toreplace, value)
                txt = replaced
                continue
    log("    processed", txt)
    return txt


def get_ws(line):
    # find whitespace
    ws = ''
    while line:
        if not line[0].isspace():
            break
        ws += line[0]
        line = line[1:]
    return ws, line


def asm_process():
    # get an input file and an output file
    args = sys.argv[1:]
    if len(args) == 0:
        infile = sys.stdin
        outfile = sys.stdout
        # read the whole lot in advance in case of in-place
        lines = list(infile.readlines())
    elif len(args) != 2:
        print("pysvp64asm [infile | -] [outfile | -]", file=sys.stderr)
        exit(0)
    else:
        if args[0] == '--':
            infile = sys.stdin
        else:
            infile = open(args[0], "r")
        # read the whole lot in advance in case of in-place overwrite
        lines = list(infile.readlines())

        if args[1] == '--':
            outfile = sys.stdout
        else:
            outfile = open(args[1], "w")

    # read the line, look for custom insn, process it
    macros = {}  # macros which start ".set"
    isa = SVP64Asm([])
    for line in lines:
        op = line.split("#")[0].strip()
        # identify macros
        if op.startswith(".set"):
            macro = op[4:].split(",")
            (macro, value) = map(str.strip, macro)
            macros[macro] = value
        if not op.startswith('sv.') and not op.startswith(tuple(CUSTOM_INSNS)):
            outfile.write(line)
            continue

        (ws, line) = get_ws(line)
        lst = isa.translate_one(op, macros)
        lst = '; '.join(lst)
        outfile.write("%s%s # %s\n" % (ws, lst, op))


if __name__ == '__main__':
    lst = ['slw 3, 1, 4',
           'extsw 5, 3',
           'sv.extsw 5, 3',
           'sv.cmpi 5, 1, 3, 2',
           'sv.setb 5, 31',
           'sv.isel 64.v, 3, 2, 65.v',
           'sv.setb/dm=r3/sm=1<<r3 5, 31',
           'sv.setb/m=r3 5, 31',
           'sv.setb/vec2 5, 31',
           'sv.setb/sw=8/ew=16 5, 31',
           'sv.extsw./ff=eq 5, 31',
           'sv.extsw./satu/sz/dz/sm=r3/dm=r3 5, 31',
           'sv.extsw./pr=eq 5.v, 31',
           'sv.add. 5.v, 2.v, 1.v',
           'sv.add./m=r3 5.v, 2.v, 1.v',
           ]
    lst += [
        'sv.stw 5.v, 4(1.v)',
        'sv.ld 5.v, 4(1.v)',
        'setvl. 2, 3, 4, 0, 1, 1',
        'sv.setvl. 2, 3, 4, 0, 1, 1',
    ]
    lst = [
        "sv.stfsu 0.v, 16(4.v)",
    ]
    lst = [
        "sv.stfsu/els 0.v, 16(4)",
    ]
    lst = [
        'sv.add./mr 5.v, 2.v, 1.v',
    ]
    macros = {'win2': '50', 'win': '60'}
    lst = [
        'sv.addi win2.v, win.v, -1',
        'sv.add./mrr 5.v, 2.v, 1.v',
        #'sv.lhzsh 5.v, 11(9.v), 15',
        #'sv.lwzsh 5.v, 11(9.v), 15',
        'sv.ffmadds 6.v, 2.v, 4.v, 6.v',
    ]
    lst = [
        #'sv.fmadds 0.v, 8.v, 16.v, 4.v',
        #'sv.ffadds 0.v, 8.v, 4.v',
        'svremap 11, 0, 1, 2, 3, 2, 1',
        'svshape 8, 1, 1, 1, 0',
        'svshape 8, 1, 1, 1, 1',
    ]
    lst = [
        #'sv.lfssh 4.v, 11(8.v), 15',
        #'sv.lwzsh 4.v, 11(8.v), 15',
        #'sv.svstep. 2.v, 4, 0',
        #'sv.fcfids. 48.v, 64.v',
        'sv.fcoss. 80.v, 0.v',
        'sv.fcoss. 20.v, 0.v',
    ]
    lst = [
        'sv.bc/all 3,12,192',
        'sv.bclr/vsbi 3,81.v,192',
        'sv.ld 5.v, 4(1.v)',
        'sv.svstep. 2.v, 4, 0',
    ]
    lst = [
        'maxs 3,12,5',
        'maxs. 3,12,5',
        'avgadd 3,12,5',
        'absdu 3,12,5',
        'absds 3,12,5',
        'absdacu 3,12,5',
        'absdacs 3,12,5',
        'cprop 3,12,5',
        'svindex 0,0,1,0,0,0,0',
    ]
    lst = [
        'sv.svstep./m=r3 2.v, 4, 0',
        'ternlogi 0,0,0,0x5',
        'fmvis 5,65535',
        'fmvis 5,1',
        'fmvis 5,32768',
    ]
    isa = SVP64Asm(lst, macros=macros)
    log("list", list(isa))
    asm_process()