497 lines
18 KiB
Python
497 lines
18 KiB
Python
"""Defining instruction set architectures."""
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from __future__ import absolute_import
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from collections import OrderedDict
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from .predicates import And, TypePredicate
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from .registers import RegClass, Register, Stack
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from .ast import Apply
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from .types import ValueType
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from .instructions import InstructionGroup
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# The typing module is only required by mypy, and we don't use these imports
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# outside type comments.
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try:
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from typing import Tuple, Union, Any, Iterable, Sequence, List, Set, Dict, TYPE_CHECKING # noqa
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if TYPE_CHECKING:
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from .instructions import MaybeBoundInst, InstructionFormat # noqa
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from .predicates import PredNode, PredKey # noqa
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from .settings import SettingGroup # noqa
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from .registers import RegBank # noqa
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from .xform import XFormGroup # noqa
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OperandConstraint = Union[RegClass, Register, int, Stack]
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ConstraintSeq = Union[OperandConstraint, Tuple[OperandConstraint, ...]]
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# Instruction specification for encodings. Allows for predicated
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# instructions.
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InstSpec = Union[MaybeBoundInst, Apply]
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BranchRange = Sequence[int]
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# A recipe predicate consisting of an ISA predicate and an instruction
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# predicate.
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RecipePred = Tuple[PredNode, PredNode]
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except ImportError:
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pass
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class TargetISA(object):
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"""
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A target instruction set architecture.
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The `TargetISA` class collects everything known about a target ISA.
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:param name: Short mnemonic name for the ISA.
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:param instruction_groups: List of `InstructionGroup` instances that are
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relevant for this ISA.
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"""
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def __init__(self, name, instruction_groups):
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# type: (str, Sequence[InstructionGroup]) -> None
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self.name = name
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self.settings = None # type: SettingGroup
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self.instruction_groups = instruction_groups
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self.cpumodes = list() # type: List[CPUMode]
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self.regbanks = list() # type: List[RegBank]
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self.regclasses = list() # type: List[RegClass]
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self.legalize_codes = OrderedDict() # type: OrderedDict[XFormGroup, int] # noqa
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# Unique copies of all predicates.
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self._predicates = dict() # type: Dict[PredKey, PredNode]
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assert InstructionGroup._current is None,\
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"InstructionGroup {} is still open!"\
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.format(InstructionGroup._current.name)
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def __str__(self):
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# type: () -> str
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return self.name
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def finish(self):
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# type: () -> TargetISA
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"""
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Finish the definition of a target ISA after adding all CPU modes and
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settings.
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This computes some derived properties that are used in multiple
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places.
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:returns self:
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"""
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self._collect_encoding_recipes()
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self._collect_predicates()
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self._collect_regclasses()
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self._collect_legalize_codes()
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return self
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def _collect_encoding_recipes(self):
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# type: () -> None
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"""
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Collect and number all encoding recipes in use.
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"""
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self.all_recipes = list() # type: List[EncRecipe]
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rcps = set() # type: Set[EncRecipe]
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for cpumode in self.cpumodes:
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for enc in cpumode.encodings:
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recipe = enc.recipe
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if recipe not in rcps:
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assert recipe.number is None
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recipe.number = len(rcps)
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rcps.add(recipe)
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self.all_recipes.append(recipe)
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# Make sure ISA predicates are registered.
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if recipe.isap:
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recipe.isap = self.unique_pred(recipe.isap)
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self.settings.number_predicate(recipe.isap)
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recipe.instp = self.unique_pred(recipe.instp)
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def _collect_predicates(self):
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# type: () -> None
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"""
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Collect and number all predicates in use.
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Ensures that all ISA predicates have an assigned bit number in
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`self.settings`.
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"""
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self.instp_number = OrderedDict() # type: OrderedDict[PredNode, int]
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for cpumode in self.cpumodes:
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for enc in cpumode.encodings:
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instp = enc.instp
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if instp and instp not in self.instp_number:
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# assign predicate number starting from 0.
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n = len(self.instp_number)
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self.instp_number[instp] = n
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# All referenced ISA predicates must have a number in
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# `self.settings`. This may cause some parent predicates to be
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# replicated here, which is OK.
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if enc.isap:
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self.settings.number_predicate(enc.isap)
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def _collect_regclasses(self):
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# type: () -> None
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"""
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Collect and number register classes.
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Every register class needs a unique index, and the classes need to be
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topologically ordered.
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We also want all the top-level register classes to be first.
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"""
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# Compute subclasses and top-level classes in each bank.
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# Collect the top-level classes so they get numbered consecutively.
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for bank in self.regbanks:
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bank.finish_regclasses()
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# Always get the pressure tracking classes in first.
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if bank.pressure_tracking:
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self.regclasses.extend(bank.toprcs)
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# The limit on the number of top-level register classes can be raised.
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# This should be coordinated with the `MAX_TRACKED_TOPRCS` constant in
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# `isa/registers.rs`.
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assert len(self.regclasses) <= 4, "Too many top-level register classes"
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# Get the remaining top-level register classes which may exceed
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# `MAX_TRACKED_TOPRCS`.
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for bank in self.regbanks:
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if not bank.pressure_tracking:
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self.regclasses.extend(bank.toprcs)
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# Collect all of the non-top-level register classes.
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# They are numbered strictly after the top-level classes.
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for bank in self.regbanks:
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self.regclasses.extend(
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rc for rc in bank.classes if not rc.is_toprc())
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for idx, rc in enumerate(self.regclasses):
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rc.index = idx
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# The limit on the number of register classes can be changed. It should
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# be coordinated with the `RegClassMask` and `RegClassIndex` types in
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# `isa/registers.rs`.
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assert len(self.regclasses) <= 32, "Too many register classes"
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def _collect_legalize_codes(self):
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# type: () -> None
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"""
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Make sure all legalization transforms have been assigned a code.
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"""
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for cpumode in self.cpumodes:
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self.legalize_code(cpumode.default_legalize)
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for x in cpumode.type_legalize.values():
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self.legalize_code(x)
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def legalize_code(self, xgrp):
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# type: (XFormGroup) -> int
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"""
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Get the legalization code for the transform group `xgrp`. Assign one if
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necessary.
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Each target ISA has its own list of legalization actions with
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associated legalize codes that appear in the encoding tables.
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This method is used to maintain the registry of legalization actions
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and their table codes.
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"""
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if xgrp in self.legalize_codes:
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code = self.legalize_codes[xgrp]
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else:
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code = len(self.legalize_codes)
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self.legalize_codes[xgrp] = code
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return code
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def unique_pred(self, pred):
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# type: (PredNode) -> PredNode
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"""
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Get a unique predicate that is equivalent to `pred`.
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"""
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if pred is None:
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return pred
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# TODO: We could actually perform some algebraic simplifications. It's
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# not clear if it is worthwhile.
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k = pred.predicate_key()
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if k in self._predicates:
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return self._predicates[k]
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self._predicates[k] = pred
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return pred
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class CPUMode(object):
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"""
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A CPU mode determines which instruction encodings are active.
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All instruction encodings are associated with exactly one `CPUMode`, and
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all CPU modes are associated with exactly one `TargetISA`.
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:param name: Short mnemonic name for the CPU mode.
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:param target: Associated `TargetISA`.
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"""
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def __init__(self, name, isa):
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# type: (str, TargetISA) -> None
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self.name = name
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self.isa = isa
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self.encodings = [] # type: List[Encoding]
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isa.cpumodes.append(self)
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# Tables for configuring legalization actions when no valid encoding
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# exists for an instruction.
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self.default_legalize = None # type: XFormGroup
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self.type_legalize = OrderedDict() # type: OrderedDict[ValueType, XFormGroup] # noqa
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def __str__(self):
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# type: () -> str
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return self.name
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def enc(self, *args, **kwargs):
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# type: (*Any, **Any) -> None
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"""
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Add a new encoding to this CPU mode.
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Arguments are the `Encoding constructor arguments, except for the first
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`CPUMode argument which is implied.
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"""
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self.encodings.append(Encoding(self, *args, **kwargs))
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def legalize_type(self, default=None, **kwargs):
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# type: (XFormGroup, **XFormGroup) -> None
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"""
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Configure the legalization action per controlling type variable.
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Instructions that have a controlling type variable mentioned in one of
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the arguments will be legalized according to the action specified here
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instead of using the `legalize_default` action.
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The keyword arguments are value type names:
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mode.legalize_type(i8=widen, i16=widen, i32=expand)
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The `default` argument specifies the action to take for controlling
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type variables that don't have an explicitly configured action.
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"""
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if default is not None:
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self.default_legalize = default
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for name, xgrp in kwargs.items():
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ty = ValueType.by_name(name)
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self.type_legalize[ty] = xgrp
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def legalize_monomorphic(self, xgrp):
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# type: (XFormGroup) -> None
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"""
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Configure the legalization action to take for monomorphic instructions
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which don't have a controlling type variable.
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See also `legalize_type()` for polymorphic instructions.
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"""
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self.type_legalize[None] = xgrp
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def get_legalize_action(self, ty):
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# type: (ValueType) -> XFormGroup
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"""
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Get the legalization action to use for `ty`.
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"""
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return self.type_legalize.get(ty, self.default_legalize)
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class EncRecipe(object):
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"""
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A recipe for encoding instructions with a given format.
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Many different instructions can be encoded by the same recipe, but they
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must all have the same instruction format.
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The `ins` and `outs` arguments are tuples specifying the register
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allocation constraints for the value operands and results respectively. The
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possible constraints for an operand are:
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- A `RegClass` specifying the set of allowed registers.
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- A `Register` specifying a fixed-register operand.
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- An integer indicating that this result is tied to a value operand, so
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they must use the same register.
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- A `Stack` specifying a value in a stack slot.
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The `branch_range` argument must be provided for recipes that can encode
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branch instructions. It is an `(origin, bits)` tuple describing the exact
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range that can be encoded in a branch instruction.
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For ISAs that use CPU flags in `iflags` and `fflags` value types, the
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`clobbers_flags` is used to indicate instruction encodings that clobbers
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the CPU flags, so they can't be used where a flag value is live.
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:param name: Short mnemonic name for this recipe.
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:param format: All encoded instructions must have this
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:py:class:`InstructionFormat`.
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:param size: Number of bytes in the binary encoded instruction.
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:param ins: Tuple of register constraints for value operands.
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:param outs: Tuple of register constraints for results.
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:param branch_range: `(origin, bits)` range for branches.
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:param clobbers_flags: This instruction clobbers `iflags` and `fflags`.
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:param instp: Instruction predicate.
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:param isap: ISA predicate.
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:param emit: Rust code for binary emission.
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"""
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def __init__(
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self,
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name, # type: str
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format, # type: InstructionFormat
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size, # type: int
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ins, # type: ConstraintSeq
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outs, # type: ConstraintSeq
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branch_range=None, # type: BranchRange
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clobbers_flags=True, # type: bool
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instp=None, # type: PredNode
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isap=None, # type: PredNode
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emit=None # type: str
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):
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# type: (...) -> None
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self.name = name
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self.format = format
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assert size >= 0
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self.size = size
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self.branch_range = branch_range
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self.clobbers_flags = clobbers_flags
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self.instp = instp
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self.isap = isap
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self.emit = emit
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if instp:
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assert instp.predicate_context() == format
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self.number = None # type: int
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self.ins = self._verify_constraints(ins)
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if not format.has_value_list:
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assert len(self.ins) == format.num_value_operands
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self.outs = self._verify_constraints(outs)
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def __str__(self):
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# type: () -> str
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return self.name
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def _verify_constraints(self, seq):
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# type: (ConstraintSeq) -> Sequence[OperandConstraint]
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if not isinstance(seq, tuple):
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seq = (seq,)
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for c in seq:
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if isinstance(c, int):
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# An integer constraint is bound to a value operand.
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# Check that it is in range.
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assert c >= 0 and c < len(self.ins)
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else:
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assert (isinstance(c, RegClass)
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or isinstance(c, Register)
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or isinstance(c, Stack))
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return seq
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def ties(self):
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# type: () -> Tuple[Dict[int, int], Dict[int, int]]
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"""
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Return two dictionaries representing the tied operands.
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The first maps input number to tied output number, the second maps
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output number to tied input number.
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"""
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i2o = dict() # type: Dict[int, int]
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o2i = dict() # type: Dict[int, int]
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for o, i in enumerate(self.outs):
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if isinstance(i, int):
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i2o[i] = o
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o2i[o] = i
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return (i2o, o2i)
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def fixed_ops(self):
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# type: () -> Tuple[Set[Register], Set[Register]]
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"""
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Return two sets of registers representing the fixed input and output
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operands.
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"""
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i = set(r for r in self.ins if isinstance(r, Register))
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o = set(r for r in self.outs if isinstance(r, Register))
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return (i, o)
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def recipe_pred(self):
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# type: () -> RecipePred
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"""
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Get the combined recipe predicate which includes both the ISA predicate
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and the instruction predicate.
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Return `None` if this recipe has neither predicate.
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"""
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if self.isap is None and self.instp is None:
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return None
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else:
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return (self.isap, self.instp)
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class Encoding(object):
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"""
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Encoding for a concrete instruction.
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An `Encoding` object ties an instruction opcode with concrete type
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variables together with and encoding recipe and encoding bits.
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The concrete instruction can be in three different forms:
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1. A naked opcode: `trap` for non-polymorphic instructions.
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2. With bound type variables: `iadd.i32` for polymorphic instructions.
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3. With operands providing constraints: `icmp.i32(intcc.eq, x, y)`.
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If the instruction is polymorphic, all type variables must be provided.
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:param cpumode: The CPU mode where the encoding is active.
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:param inst: The :py:class:`Instruction` or :py:class:`BoundInstruction`
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being encoded.
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:param recipe: The :py:class:`EncRecipe` to use.
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:param encbits: Additional encoding bits to be interpreted by `recipe`.
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:param instp: Instruction predicate, or `None`.
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:param isap: ISA predicate, or `None`.
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"""
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def __init__(self, cpumode, inst, recipe, encbits, instp=None, isap=None):
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# type: (CPUMode, InstSpec, EncRecipe, int, PredNode, PredNode) -> None # noqa
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assert isinstance(cpumode, CPUMode)
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assert isinstance(recipe, EncRecipe)
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# Check for possible instruction predicates in `inst`.
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if isinstance(inst, Apply):
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instp = And.combine(instp, inst.inst_predicate())
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self.inst = inst.inst
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self.typevars = inst.typevars
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else:
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self.inst, self.typevars = inst.fully_bound()
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# Add secondary type variables to the instruction predicate.
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# This is already included by Apply.inst_predicate() above.
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if len(self.typevars) > 1:
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for tv, vt in zip(self.inst.other_typevars, self.typevars[1:]):
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# A None tv is an 'any' wild card: `ishl.i32.any`.
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if vt is None:
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continue
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typred = TypePredicate.typevar_check(self.inst, tv, vt)
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instp = And.combine(instp, typred)
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self.cpumode = cpumode
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assert self.inst.format == recipe.format, (
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"Format {} must match recipe: {}".format(
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self.inst.format, recipe.format))
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if self.inst.is_branch:
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assert recipe.branch_range, (
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'Recipe {} for {} must have a branch_range'
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.format(recipe, self.inst.name))
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self.recipe = recipe
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self.encbits = encbits
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# Record specific predicates. Note that the recipe also has predicates.
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self.instp = self.cpumode.isa.unique_pred(instp)
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self.isap = self.cpumode.isa.unique_pred(isap)
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def __str__(self):
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# type: () -> str
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return '[{}#{:02x}]'.format(self.recipe, self.encbits)
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def ctrl_typevar(self):
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# type: () -> ValueType
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"""
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Get the controlling type variable for this encoding or `None`.
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"""
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if self.typevars:
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return self.typevars[0]
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else:
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return None
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