Source

pypy / rpython / jit / backend / x86 / regalloc.py

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""" Register allocation scheme.
"""

import os
from rpython.jit.metainterp.history import (Box, Const, ConstInt, ConstPtr,
                                            ConstFloat, BoxInt,
                                            BoxFloat, INT, REF, FLOAT,
                                            TargetToken)
from rpython.jit.backend.x86.regloc import *
from rpython.rtyper.lltypesystem import lltype, rffi, rstr
from rpython.rtyper.annlowlevel import cast_instance_to_gcref
from rpython.rlib.objectmodel import we_are_translated
from rpython.rlib import rgc
from rpython.jit.backend.llsupport import symbolic
from rpython.jit.backend.x86.jump import remap_frame_layout_mixed
from rpython.jit.codewriter import longlong
from rpython.jit.codewriter.effectinfo import EffectInfo
from rpython.jit.metainterp.resoperation import rop
from rpython.jit.backend.llsupport.descr import ArrayDescr
from rpython.jit.backend.llsupport.descr import CallDescr
from rpython.jit.backend.llsupport.descr import unpack_arraydescr
from rpython.jit.backend.llsupport.descr import unpack_fielddescr
from rpython.jit.backend.llsupport.descr import unpack_interiorfielddescr
from rpython.jit.backend.llsupport.gcmap import allocate_gcmap
from rpython.jit.backend.llsupport.regalloc import FrameManager, BaseRegalloc,\
     RegisterManager, TempBox, compute_vars_longevity, is_comparison_or_ovf_op
from rpython.jit.backend.x86.arch import WORD, JITFRAME_FIXED_SIZE
from rpython.jit.backend.x86.arch import IS_X86_32, IS_X86_64
from rpython.jit.backend.x86 import rx86
from rpython.rlib.rarithmetic import r_longlong, r_uint

class X86RegisterManager(RegisterManager):

    box_types = [INT, REF]
    all_regs = [ecx, eax, edx, ebx, esi, edi]
    no_lower_byte_regs = [esi, edi]
    save_around_call_regs = [eax, edx, ecx]
    frame_reg = ebp

    def call_result_location(self, v):
        return eax

    def convert_to_imm(self, c):
        if isinstance(c, ConstInt):
            return imm(c.value)
        elif isinstance(c, ConstPtr):
            if we_are_translated() and c.value and rgc.can_move(c.value):
                not_implemented("convert_to_imm: ConstPtr needs special care")
            return imm(rffi.cast(lltype.Signed, c.value))
        else:
            not_implemented("convert_to_imm: got a %s" % c)

class X86_64_RegisterManager(X86RegisterManager):
    # r11 omitted because it's used as scratch
    all_regs = [ecx, eax, edx, ebx, esi, edi, r8, r9, r10, r12, r13, r14, r15]

    no_lower_byte_regs = []
    save_around_call_regs = [eax, ecx, edx, esi, edi, r8, r9, r10]

class X86XMMRegisterManager(RegisterManager):

    box_types = [FLOAT]
    all_regs = [xmm0, xmm1, xmm2, xmm3, xmm4, xmm5, xmm6, xmm7]
    # we never need lower byte I hope
    save_around_call_regs = all_regs

    def convert_to_imm(self, c):
        adr = self.assembler.datablockwrapper.malloc_aligned(8, 8)
        x = c.getfloatstorage()
        rffi.cast(rffi.CArrayPtr(longlong.FLOATSTORAGE), adr)[0] = x
        return ConstFloatLoc(adr)

    def convert_to_imm_16bytes_align(self, c):
        adr = self.assembler.datablockwrapper.malloc_aligned(16, 16)
        x = c.getfloatstorage()
        y = longlong.ZEROF
        rffi.cast(rffi.CArrayPtr(longlong.FLOATSTORAGE), adr)[0] = x
        rffi.cast(rffi.CArrayPtr(longlong.FLOATSTORAGE), adr)[1] = y
        return ConstFloatLoc(adr)

    def call_result_location(self, v):
        return xmm0

class X86_64_XMMRegisterManager(X86XMMRegisterManager):
    # xmm15 reserved for scratch use
    all_regs = [xmm0, xmm1, xmm2, xmm3, xmm4, xmm5, xmm6, xmm7, xmm8, xmm9, xmm10, xmm11, xmm12, xmm13, xmm14]
    save_around_call_regs = all_regs

class X86FrameManager(FrameManager):
    def __init__(self, base_ofs):
        FrameManager.__init__(self)
        self.base_ofs = base_ofs

    def frame_pos(self, i, box_type):
        return FrameLoc(i, get_ebp_ofs(self.base_ofs, i), box_type)

    @staticmethod
    def frame_size(box_type):
        if IS_X86_32 and box_type == FLOAT:
            return 2
        else:
            return 1

    @staticmethod
    def get_loc_index(loc):
        assert isinstance(loc, FrameLoc)
        return loc.position

if WORD == 4:
    gpr_reg_mgr_cls = X86RegisterManager
    xmm_reg_mgr_cls = X86XMMRegisterManager
elif WORD == 8:
    gpr_reg_mgr_cls = X86_64_RegisterManager
    xmm_reg_mgr_cls = X86_64_XMMRegisterManager
else:
    raise AssertionError("Word size should be 4 or 8")

gpr_reg_mgr_cls.all_reg_indexes = [-1] * WORD * 2 # eh, happens to be true
for _i, _reg in enumerate(gpr_reg_mgr_cls.all_regs):
    gpr_reg_mgr_cls.all_reg_indexes[_reg.value] = _i

class RegAlloc(BaseRegalloc):

    def __init__(self, assembler, translate_support_code=False):
        assert isinstance(translate_support_code, bool)
        # variables that have place in register
        self.assembler = assembler
        self.translate_support_code = translate_support_code
        # to be read/used by the assembler too
        self.jump_target_descr = None
        self.final_jump_op = None

    def _prepare(self, inputargs, operations, allgcrefs):
        cpu = self.assembler.cpu
        self.fm = X86FrameManager(cpu.get_baseofs_of_frame_field())
        operations = cpu.gc_ll_descr.rewrite_assembler(cpu, operations,
                                                       allgcrefs)
        # compute longevity of variables
        longevity, last_real_usage = compute_vars_longevity(
                                                    inputargs, operations)
        self.longevity = longevity
        self.last_real_usage = last_real_usage
        self.rm = gpr_reg_mgr_cls(self.longevity,
                                  frame_manager = self.fm,
                                  assembler = self.assembler)
        self.xrm = xmm_reg_mgr_cls(self.longevity, frame_manager = self.fm,
                                   assembler = self.assembler)
        return operations

    def prepare_loop(self, inputargs, operations, looptoken, allgcrefs):
        operations = self._prepare(inputargs, operations, allgcrefs)
        self._set_initial_bindings(inputargs, looptoken)
        # note: we need to make a copy of inputargs because possibly_free_vars
        # is also used on op args, which is a non-resizable list
        self.possibly_free_vars(list(inputargs))
        if WORD == 4:       # see redirect_call_assembler()
            self.min_bytes_before_label = 5
        else:
            self.min_bytes_before_label = 13
        return operations

    def prepare_bridge(self, inputargs, arglocs, operations, allgcrefs,
                       frame_info):
        operations = self._prepare(inputargs, operations, allgcrefs)
        self._update_bindings(arglocs, inputargs)
        self.min_bytes_before_label = 0
        return operations

    def ensure_next_label_is_at_least_at_position(self, at_least_position):
        self.min_bytes_before_label = max(self.min_bytes_before_label,
                                          at_least_position)

    def get_final_frame_depth(self):
        return self.fm.get_frame_depth()

    def possibly_free_var(self, var):
        if var.type == FLOAT:
            self.xrm.possibly_free_var(var)
        else:
            self.rm.possibly_free_var(var)

    def possibly_free_vars_for_op(self, op):
        for i in range(op.numargs()):
            var = op.getarg(i)
            if var is not None: # xxx kludgy
                self.possibly_free_var(var)
        if op.result:
            self.possibly_free_var(op.result)

    def possibly_free_vars(self, vars):
        for var in vars:
            if var is not None: # xxx kludgy
                self.possibly_free_var(var)

    def make_sure_var_in_reg(self, var, forbidden_vars=[],
                             selected_reg=None, need_lower_byte=False):
        if var.type == FLOAT:
            if isinstance(var, ConstFloat):
                return FloatImmedLoc(var.getfloatstorage())
            return self.xrm.make_sure_var_in_reg(var, forbidden_vars,
                                                 selected_reg, need_lower_byte)
        else:
            return self.rm.make_sure_var_in_reg(var, forbidden_vars,
                                                selected_reg, need_lower_byte)

    def force_allocate_reg(self, var, forbidden_vars=[], selected_reg=None,
                           need_lower_byte=False):
        if var.type == FLOAT:
            return self.xrm.force_allocate_reg(var, forbidden_vars,
                                               selected_reg, need_lower_byte)
        else:
            return self.rm.force_allocate_reg(var, forbidden_vars,
                                              selected_reg, need_lower_byte)

    def force_spill_var(self, var):
        if var.type == FLOAT:
            return self.xrm.force_spill_var(var)
        else:
            return self.rm.force_spill_var(var)

    def load_xmm_aligned_16_bytes(self, var, forbidden_vars=[]):
        # Load 'var' in a register; but if it is a constant, we can return
        # a 16-bytes-aligned ConstFloatLoc.
        if isinstance(var, Const):
            return self.xrm.convert_to_imm_16bytes_align(var)
        else:
            return self.xrm.make_sure_var_in_reg(var, forbidden_vars)

    def _frame_bindings(self, locs, inputargs):
        bindings = {}
        i = 0
        for loc in locs:
            if loc is None:
                continue
            arg = inputargs[i]
            i += 1
            if not isinstance(loc, RegLoc):
                bindings[arg] = loc
        return bindings

    def _update_bindings(self, locs, inputargs):
        # XXX this should probably go to llsupport/regalloc.py
        used = {}
        i = 0
        for loc in locs:
            if loc is None: # xxx bit kludgy
                loc = ebp
            arg = inputargs[i]
            i += 1
            if isinstance(loc, RegLoc):
                if arg.type == FLOAT:
                    self.xrm.reg_bindings[arg] = loc
                    used[loc] = None
                else:
                    if loc is ebp:
                        self.rm.bindings_to_frame_reg[arg] = None
                    else:
                        self.rm.reg_bindings[arg] = loc
                        used[loc] = None
            else:
                self.fm.bind(arg, loc)
        self.rm.free_regs = []
        for reg in self.rm.all_regs:
            if reg not in used:
                self.rm.free_regs.append(reg)
        self.xrm.free_regs = []
        for reg in self.xrm.all_regs:
            if reg not in used:
                self.xrm.free_regs.append(reg)
        self.possibly_free_vars(list(inputargs))
        self.fm.finish_binding()
        self.rm._check_invariants()
        self.xrm._check_invariants()

    def perform(self, op, arglocs, result_loc):
        if not we_are_translated():
            self.assembler.dump('%s <- %s(%s)' % (result_loc, op, arglocs))
        self.assembler.regalloc_perform(op, arglocs, result_loc)

    def perform_llong(self, op, arglocs, result_loc):
        if not we_are_translated():
            self.assembler.dump('%s <- %s(%s)' % (result_loc, op, arglocs))
        self.assembler.regalloc_perform_llong(op, arglocs, result_loc)

    def perform_math(self, op, arglocs, result_loc):
        if not we_are_translated():
            self.assembler.dump('%s <- %s(%s)' % (result_loc, op, arglocs))
        self.assembler.regalloc_perform_math(op, arglocs, result_loc)

    def locs_for_fail(self, guard_op):
        return [self.loc(v) for v in guard_op.getfailargs()]

    def perform_with_guard(self, op, guard_op, arglocs, result_loc):
        faillocs = self.locs_for_fail(guard_op)
        self.rm.position += 1
        self.xrm.position += 1
        self.assembler.regalloc_perform_with_guard(op, guard_op, faillocs,
                                                   arglocs, result_loc,
                                                   self.fm.get_frame_depth())
        self.possibly_free_vars(guard_op.getfailargs())

    def perform_guard(self, guard_op, arglocs, result_loc):
        faillocs = self.locs_for_fail(guard_op)
        if not we_are_translated():
            if result_loc is not None:
                self.assembler.dump('%s <- %s(%s)' % (result_loc, guard_op,
                                                      arglocs))
            else:
                self.assembler.dump('%s(%s)' % (guard_op, arglocs))
        self.assembler.regalloc_perform_guard(guard_op, faillocs, arglocs,
                                              result_loc,
                                              self.fm.get_frame_depth())
        self.possibly_free_vars(guard_op.getfailargs())

    def perform_discard(self, op, arglocs):
        if not we_are_translated():
            self.assembler.dump('%s(%s)' % (op, arglocs))
        self.assembler.regalloc_perform_discard(op, arglocs)

    def walk_operations(self, inputargs, operations):
        i = 0
        #self.operations = operations
        while i < len(operations):
            op = operations[i]
            self.assembler.mc.mark_op(op)
            self.rm.position = i
            self.xrm.position = i
            if op.has_no_side_effect() and op.result not in self.longevity:
                i += 1
                self.possibly_free_vars_for_op(op)
                continue
            if self.can_merge_with_next_guard(op, i, operations):
                oplist_with_guard[op.getopnum()](self, op, operations[i + 1])
                i += 1
            elif not we_are_translated() and op.getopnum() == -124:
                self._consider_force_spill(op)
            else:
                oplist[op.getopnum()](self, op)
            self.possibly_free_vars_for_op(op)
            self.rm._check_invariants()
            self.xrm._check_invariants()
            i += 1
        assert not self.rm.reg_bindings
        assert not self.xrm.reg_bindings
        self.flush_loop()
        self.assembler.mc.mark_op(None) # end of the loop
        for arg in inputargs:
            self.possibly_free_var(arg)

    def flush_loop(self):
        # rare case: if the loop is too short, or if we are just after
        # a GUARD_NOT_INVALIDATED, pad with NOPs.  Important!  This must
        # be called to ensure that there are enough bytes produced,
        # because GUARD_NOT_INVALIDATED or redirect_call_assembler()
        # will maybe overwrite them.
        mc = self.assembler.mc
        while mc.get_relative_pos() < self.min_bytes_before_label:
            mc.NOP()

    def loc(self, v):
        if v is None: # xxx kludgy
            return None
        if v.type == FLOAT:
            return self.xrm.loc(v)
        return self.rm.loc(v)

    def _consider_guard(self, op):
        loc = self.rm.make_sure_var_in_reg(op.getarg(0))
        self.perform_guard(op, [loc], None)

    consider_guard_true = _consider_guard
    consider_guard_false = _consider_guard
    consider_guard_nonnull = _consider_guard
    consider_guard_isnull = _consider_guard

    def consider_finish(self, op):
        # the frame is in ebp, but we have to point where in the frame is
        # the potential argument to FINISH
        descr = op.getdescr()
        fail_descr = cast_instance_to_gcref(descr)
        # we know it does not move, but well
        rgc._make_sure_does_not_move(fail_descr)
        fail_descr = rffi.cast(lltype.Signed, fail_descr)
        if op.numargs() == 1:
            loc = self.make_sure_var_in_reg(op.getarg(0))
            locs = [loc, imm(fail_descr)]
        else:
            locs = [imm(fail_descr)]
        self.perform(op, locs, None)

    def consider_guard_no_exception(self, op):
        self.perform_guard(op, [], None)

    def consider_guard_not_invalidated(self, op):
        mc = self.assembler.mc
        n = mc.get_relative_pos()
        self.perform_guard(op, [], None)
        assert n == mc.get_relative_pos()
        # ensure that the next label is at least 5 bytes farther than
        # the current position.  Otherwise, when invalidating the guard,
        # we would overwrite randomly the next label's position.
        self.ensure_next_label_is_at_least_at_position(n + 5)

    def consider_guard_exception(self, op):
        loc = self.rm.make_sure_var_in_reg(op.getarg(0))
        box = TempBox()
        args = op.getarglist()
        loc1 = self.rm.force_allocate_reg(box, args)
        if op.result in self.longevity:
            # this means, is it ever used
            resloc = self.rm.force_allocate_reg(op.result, args + [box])
        else:
            resloc = None
        self.perform_guard(op, [loc, loc1], resloc)
        self.rm.possibly_free_var(box)

    consider_guard_no_overflow = consider_guard_no_exception
    consider_guard_overflow    = consider_guard_no_exception

    def consider_guard_value(self, op):
        x = self.make_sure_var_in_reg(op.getarg(0))
        y = self.loc(op.getarg(1))
        self.perform_guard(op, [x, y], None)

    def consider_guard_class(self, op):
        assert isinstance(op.getarg(0), Box)
        x = self.rm.make_sure_var_in_reg(op.getarg(0))
        y = self.loc(op.getarg(1))
        self.perform_guard(op, [x, y], None)

    consider_guard_nonnull_class = consider_guard_class

    def _consider_binop_part(self, op):
        x = op.getarg(0)
        argloc = self.loc(op.getarg(1))
        args = op.getarglist()
        loc = self.rm.force_result_in_reg(op.result, x, args)
        return loc, argloc

    def _consider_binop(self, op):
        loc, argloc = self._consider_binop_part(op)
        self.perform(op, [loc, argloc], loc)

    def _consider_lea(self, op, loc):
        argloc = self.loc(op.getarg(1))
        resloc = self.force_allocate_reg(op.result)
        self.perform(op, [loc, argloc], resloc)

    def consider_int_add(self, op):
        loc = self.loc(op.getarg(0))
        y = op.getarg(1)
        if (isinstance(loc, RegLoc) and
            isinstance(y, ConstInt) and rx86.fits_in_32bits(y.value)):
            self._consider_lea(op, loc)
        else:
            self._consider_binop(op)

    def consider_int_sub(self, op):
        loc = self.loc(op.getarg(0))
        y = op.getarg(1)
        if (isinstance(loc, RegLoc) and
            isinstance(y, ConstInt) and rx86.fits_in_32bits(-y.value)):
            self._consider_lea(op, loc)
        else:
            self._consider_binop(op)

    consider_int_mul = _consider_binop
    consider_int_and = _consider_binop
    consider_int_or  = _consider_binop
    consider_int_xor = _consider_binop

    def _consider_binop_with_guard(self, op, guard_op):
        loc, argloc = self._consider_binop_part(op)
        self.perform_with_guard(op, guard_op, [loc, argloc], loc)

    consider_int_mul_ovf = _consider_binop_with_guard
    consider_int_sub_ovf = _consider_binop_with_guard
    consider_int_add_ovf = _consider_binop_with_guard

    def consider_int_neg(self, op):
        res = self.rm.force_result_in_reg(op.result, op.getarg(0))
        self.perform(op, [res], res)

    consider_int_invert = consider_int_neg

    def consider_int_lshift(self, op):
        if isinstance(op.getarg(1), Const):
            loc2 = self.rm.convert_to_imm(op.getarg(1))
        else:
            loc2 = self.rm.make_sure_var_in_reg(op.getarg(1), selected_reg=ecx)
        args = op.getarglist()
        loc1 = self.rm.force_result_in_reg(op.result, op.getarg(0), args)
        self.perform(op, [loc1, loc2], loc1)

    consider_int_rshift  = consider_int_lshift
    consider_uint_rshift = consider_int_lshift

    def _consider_int_div_or_mod(self, op, resultreg, trashreg):
        l0 = self.rm.make_sure_var_in_reg(op.getarg(0), selected_reg=eax)
        l1 = self.rm.make_sure_var_in_reg(op.getarg(1), selected_reg=ecx)
        l2 = self.rm.force_allocate_reg(op.result, selected_reg=resultreg)
        # the register (eax or edx) not holding what we are looking for
        # will be just trash after that operation
        tmpvar = TempBox()
        self.rm.force_allocate_reg(tmpvar, selected_reg=trashreg)
        assert l0 is eax
        assert l1 is ecx
        assert l2 is resultreg
        self.rm.possibly_free_var(tmpvar)

    def consider_int_mod(self, op):
        self._consider_int_div_or_mod(op, edx, eax)
        self.perform(op, [eax, ecx], edx)

    def consider_int_floordiv(self, op):
        self._consider_int_div_or_mod(op, eax, edx)
        self.perform(op, [eax, ecx], eax)

    consider_uint_floordiv = consider_int_floordiv

    def _consider_compop(self, op, guard_op):
        vx = op.getarg(0)
        vy = op.getarg(1)
        arglocs = [self.loc(vx), self.loc(vy)]
        args = op.getarglist()
        if (vx in self.rm.reg_bindings or vy in self.rm.reg_bindings or
            isinstance(vx, Const) or isinstance(vy, Const)):
            pass
        else:
            arglocs[0] = self.rm.make_sure_var_in_reg(vx)
        if guard_op is None:
            loc = self.rm.force_allocate_reg(op.result, args,
                                             need_lower_byte=True)
            self.perform(op, arglocs, loc)
        else:
            self.perform_with_guard(op, guard_op, arglocs, None)

    consider_int_lt = _consider_compop
    consider_int_gt = _consider_compop
    consider_int_ge = _consider_compop
    consider_int_le = _consider_compop
    consider_int_ne = _consider_compop
    consider_int_eq = _consider_compop
    consider_uint_gt = _consider_compop
    consider_uint_lt = _consider_compop
    consider_uint_le = _consider_compop
    consider_uint_ge = _consider_compop
    consider_ptr_eq = consider_instance_ptr_eq = _consider_compop
    consider_ptr_ne = consider_instance_ptr_ne = _consider_compop

    def _consider_float_op(self, op):
        loc1 = self.xrm.loc(op.getarg(1))
        args = op.getarglist()
        loc0 = self.xrm.force_result_in_reg(op.result, op.getarg(0), args)
        self.perform(op, [loc0, loc1], loc0)

    consider_float_add = _consider_float_op
    consider_float_sub = _consider_float_op
    consider_float_mul = _consider_float_op
    consider_float_truediv = _consider_float_op

    def _consider_float_cmp(self, op, guard_op):
        vx = op.getarg(0)
        vy = op.getarg(1)
        arglocs = [self.loc(vx), self.loc(vy)]
        if not (isinstance(arglocs[0], RegLoc) or
                isinstance(arglocs[1], RegLoc)):
            if isinstance(vx, Const):
                arglocs[1] = self.xrm.make_sure_var_in_reg(vy)
            else:
                arglocs[0] = self.xrm.make_sure_var_in_reg(vx)
        if guard_op is None:
            res = self.rm.force_allocate_reg(op.result, need_lower_byte=True)
            self.perform(op, arglocs, res)
        else:
            self.perform_with_guard(op, guard_op, arglocs, None)

    consider_float_lt = _consider_float_cmp
    consider_float_le = _consider_float_cmp
    consider_float_eq = _consider_float_cmp
    consider_float_ne = _consider_float_cmp
    consider_float_gt = _consider_float_cmp
    consider_float_ge = _consider_float_cmp

    def _consider_float_unary_op(self, op):
        loc0 = self.xrm.force_result_in_reg(op.result, op.getarg(0))
        self.perform(op, [loc0], loc0)

    consider_float_neg = _consider_float_unary_op
    consider_float_abs = _consider_float_unary_op

    def consider_cast_float_to_int(self, op):
        loc0 = self.xrm.make_sure_var_in_reg(op.getarg(0))
        loc1 = self.rm.force_allocate_reg(op.result)
        self.perform(op, [loc0], loc1)

    def consider_cast_int_to_float(self, op):
        loc0 = self.rm.make_sure_var_in_reg(op.getarg(0))
        loc1 = self.xrm.force_allocate_reg(op.result)
        self.perform(op, [loc0], loc1)

    def consider_cast_float_to_singlefloat(self, op):
        loc0 = self.xrm.make_sure_var_in_reg(op.getarg(0))
        loc1 = self.rm.force_allocate_reg(op.result)
        tmpxvar = TempBox()
        loctmp = self.xrm.force_allocate_reg(tmpxvar)   # may be equal to loc0
        self.xrm.possibly_free_var(tmpxvar)
        self.perform(op, [loc0, loctmp], loc1)

    consider_cast_singlefloat_to_float = consider_cast_int_to_float

    def consider_convert_float_bytes_to_longlong(self, op):
        if longlong.is_64_bit:
            loc0 = self.xrm.make_sure_var_in_reg(op.getarg(0))
            loc1 = self.rm.force_allocate_reg(op.result)
            self.perform(op, [loc0], loc1)
        else:
            arg0 = op.getarg(0)
            loc0 = self.xrm.loc(arg0)
            loc1 = self.xrm.force_allocate_reg(op.result, forbidden_vars=[arg0])
            self.perform(op, [loc0], loc1)

    def consider_convert_longlong_bytes_to_float(self, op):
        if longlong.is_64_bit:
            loc0 = self.rm.make_sure_var_in_reg(op.getarg(0))
            loc1 = self.xrm.force_allocate_reg(op.result)
            self.perform(op, [loc0], loc1)
        else:
            arg0 = op.getarg(0)
            loc0 = self.xrm.make_sure_var_in_reg(arg0)
            loc1 = self.xrm.force_allocate_reg(op.result, forbidden_vars=[arg0])
            self.perform(op, [loc0], loc1)

    def _consider_llong_binop_xx(self, op):
        # must force both arguments into xmm registers, because we don't
        # know if they will be suitably aligned.  Exception: if the second
        # argument is a constant, we can ask it to be aligned to 16 bytes.
        args = [op.getarg(1), op.getarg(2)]
        loc1 = self.load_xmm_aligned_16_bytes(args[1])
        loc0 = self.xrm.force_result_in_reg(op.result, args[0], args)
        self.perform_llong(op, [loc0, loc1], loc0)

    def _consider_llong_eq_ne_xx(self, op):
        # must force both arguments into xmm registers, because we don't
        # know if they will be suitably aligned.  Exception: if they are
        # constants, we can ask them to be aligned to 16 bytes.
        args = [op.getarg(1), op.getarg(2)]
        loc1 = self.load_xmm_aligned_16_bytes(args[0])
        loc2 = self.load_xmm_aligned_16_bytes(args[1], args)
        tmpxvar = TempBox()
        loc3 = self.xrm.force_allocate_reg(tmpxvar, args)
        self.xrm.possibly_free_var(tmpxvar)
        loc0 = self.rm.force_allocate_reg(op.result, need_lower_byte=True)
        self.perform_llong(op, [loc1, loc2, loc3], loc0)

    def _maybe_consider_llong_lt(self, op):
        # XXX just a special case for now
        box = op.getarg(2)
        if not isinstance(box, ConstFloat):
            return False
        if box.getlonglong() != 0:
            return False
        # "x < 0"
        box = op.getarg(1)
        assert isinstance(box, BoxFloat)
        loc1 = self.xrm.make_sure_var_in_reg(box)
        loc0 = self.rm.force_allocate_reg(op.result)
        self.perform_llong(op, [loc1], loc0)
        return True

    def _consider_llong_to_int(self, op):
        # accept an argument in a xmm register or in the stack
        loc1 = self.xrm.loc(op.getarg(1))
        loc0 = self.rm.force_allocate_reg(op.result)
        self.perform_llong(op, [loc1], loc0)

    def _loc_of_const_longlong(self, value64):
        c = ConstFloat(value64)
        return self.xrm.convert_to_imm(c)

    def _consider_llong_from_int(self, op):
        assert IS_X86_32
        loc0 = self.xrm.force_allocate_reg(op.result)
        box = op.getarg(1)
        if isinstance(box, ConstInt):
            loc1 = self._loc_of_const_longlong(r_longlong(box.value))
            loc2 = None    # unused
        else:
            loc1 = self.rm.make_sure_var_in_reg(box)
            tmpxvar = TempBox()
            loc2 = self.xrm.force_allocate_reg(tmpxvar, [op.result])
            self.xrm.possibly_free_var(tmpxvar)
        self.perform_llong(op, [loc1, loc2], loc0)

    def _consider_llong_from_uint(self, op):
        assert IS_X86_32
        loc0 = self.xrm.force_allocate_reg(op.result)
        loc1 = self.rm.make_sure_var_in_reg(op.getarg(1))
        self.perform_llong(op, [loc1], loc0)

    def _consider_math_sqrt(self, op):
        loc0 = self.xrm.force_result_in_reg(op.result, op.getarg(1))
        self.perform_math(op, [loc0], loc0)

    def _call(self, op, arglocs, force_store=[], guard_not_forced_op=None):
        # we need to save registers on the stack:
        #
        #  - at least the non-callee-saved registers
        #
        #  - we assume that any call can collect, and we
        #    save also the callee-saved registers that contain GC pointers
        #
        #  - for CALL_MAY_FORCE or CALL_ASSEMBLER, we have to save all regs
        #    anyway, in case we need to do cpu.force().  The issue is that
        #    grab_frame_values() would not be able to locate values in
        #    callee-saved registers.
        #
        save_all_regs = guard_not_forced_op is not None
        self.xrm.before_call(force_store, save_all_regs=save_all_regs)
        if not save_all_regs:
            gcrootmap = self.assembler.cpu.gc_ll_descr.gcrootmap
            # we save all the registers for shadowstack and asmgcc for now
            # --- for asmgcc too: we can't say "register x is a gc ref"
            # without distinguishing call sites, which we don't do any
            # more for now.
            if gcrootmap: # and gcrootmap.is_shadow_stack:
                save_all_regs = 2
        self.rm.before_call(force_store, save_all_regs=save_all_regs)
        if op.result is not None:
            if op.result.type == FLOAT:
                resloc = self.xrm.after_call(op.result)
            else:
                resloc = self.rm.after_call(op.result)
        else:
            resloc = None
        if guard_not_forced_op is not None:
            self.perform_with_guard(op, guard_not_forced_op, arglocs, resloc)
        else:
            self.perform(op, arglocs, resloc)

    def _consider_call(self, op, guard_not_forced_op=None):
        calldescr = op.getdescr()
        assert isinstance(calldescr, CallDescr)
        assert len(calldescr.arg_classes) == op.numargs() - 1
        size = calldescr.get_result_size()
        sign = calldescr.is_result_signed()
        if sign:
            sign_loc = imm1
        else:
            sign_loc = imm0
        self._call(op, [imm(size), sign_loc] +
                       [self.loc(op.getarg(i)) for i in range(op.numargs())],
                   guard_not_forced_op=guard_not_forced_op)

    def consider_call(self, op):
        effectinfo = op.getdescr().get_extra_info()
        oopspecindex = effectinfo.oopspecindex
        if oopspecindex != EffectInfo.OS_NONE:
            if IS_X86_32:
                # support for some of the llong operations,
                # which only exist on x86-32
                if oopspecindex in (EffectInfo.OS_LLONG_ADD,
                                    EffectInfo.OS_LLONG_SUB,
                                    EffectInfo.OS_LLONG_AND,
                                    EffectInfo.OS_LLONG_OR,
                                    EffectInfo.OS_LLONG_XOR):
                    return self._consider_llong_binop_xx(op)
                if oopspecindex == EffectInfo.OS_LLONG_TO_INT:
                    return self._consider_llong_to_int(op)
                if oopspecindex == EffectInfo.OS_LLONG_FROM_INT:
                    return self._consider_llong_from_int(op)
                if oopspecindex == EffectInfo.OS_LLONG_FROM_UINT:
                    return self._consider_llong_from_uint(op)
                if (oopspecindex == EffectInfo.OS_LLONG_EQ or
                    oopspecindex == EffectInfo.OS_LLONG_NE):
                    return self._consider_llong_eq_ne_xx(op)
                if oopspecindex == EffectInfo.OS_LLONG_LT:
                    if self._maybe_consider_llong_lt(op):
                        return
            if oopspecindex == EffectInfo.OS_MATH_SQRT:
                return self._consider_math_sqrt(op)
        self._consider_call(op)

    def consider_call_may_force(self, op, guard_op):
        assert guard_op is not None
        self._consider_call(op, guard_op)

    def consider_call_release_gil(self, op, guard_op):
        assert guard_op is not None
        self._consider_call(op, guard_op)

    def consider_call_malloc_gc(self, op):
        self._consider_call(op)

    def consider_call_assembler(self, op, guard_op):
        locs = self.locs_for_call_assembler(op, guard_op)
        self._call(op, locs, guard_not_forced_op=guard_op)

    def consider_cond_call_gc_wb(self, op):
        assert op.result is None
        args = op.getarglist()
        N = len(args)
        # we force all arguments in a reg (unless they are Consts),
        # because it will be needed anyway by the following setfield_gc
        # or setarrayitem_gc. It avoids loading it twice from the memory.
        arglocs = [self.rm.make_sure_var_in_reg(op.getarg(i), args)
                   for i in range(N)]
        self.perform_discard(op, arglocs)

    consider_cond_call_gc_wb_array = consider_cond_call_gc_wb

    def consider_call_malloc_nursery(self, op):
        size_box = op.getarg(0)
        assert isinstance(size_box, ConstInt)
        size = size_box.getint()
        # looking at the result
        self.rm.force_allocate_reg(op.result, selected_reg=eax)
        #
        # We need edi as a temporary, but otherwise don't save any more
        # register.  See comments in _build_malloc_slowpath().
        tmp_box = TempBox()
        self.rm.force_allocate_reg(tmp_box, selected_reg=edi)
        gcmap = self.get_gcmap([eax, edi]) # allocate the gcmap *before*
        self.rm.possibly_free_var(tmp_box)
        #
        gc_ll_descr = self.assembler.cpu.gc_ll_descr
        self.assembler.malloc_cond(
            gc_ll_descr.get_nursery_free_addr(),
            gc_ll_descr.get_nursery_top_addr(),
            size, gcmap)

    def consider_call_malloc_nursery_varsize_frame(self, op):
        size_box = op.getarg(0)
        assert isinstance(size_box, BoxInt) # we cannot have a const here!
        # sizeloc must be in a register, but we can free it now
        # (we take care explicitly of conflicts with eax or edi)
        sizeloc = self.rm.make_sure_var_in_reg(size_box)
        self.rm.possibly_free_var(size_box)
        # the result will be in eax
        self.rm.force_allocate_reg(op.result, selected_reg=eax)
        # we need edi as a temporary
        tmp_box = TempBox()
        self.rm.force_allocate_reg(tmp_box, selected_reg=edi)
        gcmap = self.get_gcmap([eax, edi]) # allocate the gcmap *before*
        self.rm.possibly_free_var(tmp_box)
        #
        gc_ll_descr = self.assembler.cpu.gc_ll_descr
        self.assembler.malloc_cond_varsize_frame(
            gc_ll_descr.get_nursery_free_addr(),
            gc_ll_descr.get_nursery_top_addr(),
            sizeloc, gcmap)

    def consider_call_malloc_nursery_varsize(self, op):
        gc_ll_descr = self.assembler.cpu.gc_ll_descr
        if not hasattr(gc_ll_descr, 'max_size_of_young_obj'):
            raise Exception("unreachable code")
            # for boehm, this function should never be called
        arraydescr = op.getdescr()
        length_box = op.getarg(2)
        assert isinstance(length_box, BoxInt) # we cannot have a const here!
        # the result will be in eax
        self.rm.force_allocate_reg(op.result, selected_reg=eax)
        # we need edi as a temporary
        tmp_box = TempBox()
        self.rm.force_allocate_reg(tmp_box, selected_reg=edi)
        gcmap = self.get_gcmap([eax, edi]) # allocate the gcmap *before*
        self.rm.possibly_free_var(tmp_box)
        # length_box always survives: it's typically also present in the
        # next operation that will copy it inside the new array.  It's
        # fine to load it from the stack too, as long as it's != eax, edi.
        lengthloc = self.rm.loc(length_box)
        self.rm.possibly_free_var(length_box)
        #
        itemsize = op.getarg(1).getint()
        maxlength = (gc_ll_descr.max_size_of_young_obj - WORD * 2) / itemsize
        self.assembler.malloc_cond_varsize(
            op.getarg(0).getint(),
            gc_ll_descr.get_nursery_free_addr(),
            gc_ll_descr.get_nursery_top_addr(),
            lengthloc, itemsize, maxlength, gcmap, arraydescr)

    def get_gcmap(self, forbidden_regs=[], noregs=False):
        frame_depth = self.fm.get_frame_depth()
        gcmap = allocate_gcmap(self.assembler, frame_depth, JITFRAME_FIXED_SIZE)
        for box, loc in self.rm.reg_bindings.iteritems():
            if loc in forbidden_regs:
                continue
            if box.type == REF and self.rm.is_still_alive(box):
                assert not noregs
                assert isinstance(loc, RegLoc)
                val = gpr_reg_mgr_cls.all_reg_indexes[loc.value]
                gcmap[val // WORD // 8] |= r_uint(1) << (val % (WORD * 8))
        for box, loc in self.fm.bindings.iteritems():
            if box.type == REF and self.rm.is_still_alive(box):
                assert isinstance(loc, FrameLoc)
                val = loc.position + JITFRAME_FIXED_SIZE
                gcmap[val // WORD // 8] |= r_uint(1) << (val % (WORD * 8))
        return gcmap


    def consider_setfield_gc(self, op):
        ofs, size, _ = unpack_fielddescr(op.getdescr())
        ofs_loc = imm(ofs)
        size_loc = imm(size)
        assert isinstance(size_loc, ImmedLoc)
        if size_loc.value == 1:
            need_lower_byte = True
        else:
            need_lower_byte = False
        args = op.getarglist()
        base_loc = self.rm.make_sure_var_in_reg(op.getarg(0), args)
        value_loc = self.make_sure_var_in_reg(op.getarg(1), args,
                                              need_lower_byte=need_lower_byte)
        self.perform_discard(op, [base_loc, ofs_loc, size_loc, value_loc])

    consider_setfield_raw = consider_setfield_gc

    def consider_setinteriorfield_gc(self, op):
        t = unpack_interiorfielddescr(op.getdescr())
        ofs, itemsize, fieldsize = imm(t[0]), imm(t[1]), imm(t[2])
        args = op.getarglist()
        if fieldsize.value == 1:
            need_lower_byte = True
        else:
            need_lower_byte = False
        box_base, box_index, box_value = args
        base_loc = self.rm.make_sure_var_in_reg(box_base, args)
        index_loc = self.rm.make_sure_var_in_reg(box_index, args)
        value_loc = self.make_sure_var_in_reg(box_value, args,
                                              need_lower_byte=need_lower_byte)
        # If 'index_loc' is not an immediate, then we need a 'temp_loc' that
        # is a register whose value will be destroyed.  It's fine to destroy
        # the same register as 'index_loc', but not the other ones.
        if not isinstance(index_loc, ImmedLoc):
            # ...that is, except in a corner case where 'index_loc' would be
            # in the same register as 'value_loc'...
            tempvar = TempBox()
            temp_loc = self.rm.force_allocate_reg(tempvar, [box_base,
                                                            box_value])
            self.rm.possibly_free_var(tempvar)
        else:
            temp_loc = None
        self.rm.possibly_free_var(box_index)
        self.rm.possibly_free_var(box_base)
        self.possibly_free_var(box_value)
        self.perform_discard(op, [base_loc, ofs, itemsize, fieldsize,
                                 index_loc, temp_loc, value_loc])

    consider_setinteriorfield_raw = consider_setinteriorfield_gc

    def consider_strsetitem(self, op):
        args = op.getarglist()
        base_loc = self.rm.make_sure_var_in_reg(op.getarg(0), args)
        ofs_loc = self.rm.make_sure_var_in_reg(op.getarg(1), args)
        value_loc = self.rm.make_sure_var_in_reg(op.getarg(2), args,
                                                 need_lower_byte=True)
        self.perform_discard(op, [base_loc, ofs_loc, value_loc])

    consider_unicodesetitem = consider_strsetitem

    def consider_setarrayitem_gc(self, op):
        itemsize, ofs, _ = unpack_arraydescr(op.getdescr())
        args = op.getarglist()
        base_loc  = self.rm.make_sure_var_in_reg(op.getarg(0), args)
        if itemsize == 1:
            need_lower_byte = True
        else:
            need_lower_byte = False
        value_loc = self.make_sure_var_in_reg(op.getarg(2), args,
                                          need_lower_byte=need_lower_byte)
        ofs_loc = self.rm.make_sure_var_in_reg(op.getarg(1), args)
        self.perform_discard(op, [base_loc, ofs_loc, value_loc,
                                 imm(itemsize), imm(ofs)])

    consider_setarrayitem_raw = consider_setarrayitem_gc
    consider_raw_store = consider_setarrayitem_gc

    def consider_getfield_gc(self, op):
        ofs, size, sign = unpack_fielddescr(op.getdescr())
        ofs_loc = imm(ofs)
        size_loc = imm(size)
        args = op.getarglist()
        base_loc = self.rm.make_sure_var_in_reg(op.getarg(0), args)
        result_loc = self.force_allocate_reg(op.result)
        if sign:
            sign_loc = imm1
        else:
            sign_loc = imm0
        self.perform(op, [base_loc, ofs_loc, size_loc, sign_loc], result_loc)

    consider_getfield_raw = consider_getfield_gc
    consider_getfield_raw_pure = consider_getfield_gc
    consider_getfield_gc_pure = consider_getfield_gc

    def consider_getarrayitem_gc(self, op):
        itemsize, ofs, sign = unpack_arraydescr(op.getdescr())
        args = op.getarglist()
        base_loc = self.rm.make_sure_var_in_reg(op.getarg(0), args)
        ofs_loc = self.rm.make_sure_var_in_reg(op.getarg(1), args)
        result_loc = self.force_allocate_reg(op.result)
        if sign:
            sign_loc = imm1
        else:
            sign_loc = imm0
        self.perform(op, [base_loc, ofs_loc, imm(itemsize), imm(ofs),
                          sign_loc], result_loc)

    consider_getarrayitem_raw = consider_getarrayitem_gc
    consider_getarrayitem_gc_pure = consider_getarrayitem_gc
    consider_getarrayitem_raw_pure = consider_getarrayitem_gc
    consider_raw_load = consider_getarrayitem_gc

    def consider_getinteriorfield_gc(self, op):
        t = unpack_interiorfielddescr(op.getdescr())
        ofs, itemsize, fieldsize, sign = imm(t[0]), imm(t[1]), imm(t[2]), t[3]
        if sign:
            sign_loc = imm1
        else:
            sign_loc = imm0
        args = op.getarglist()
        base_loc = self.rm.make_sure_var_in_reg(op.getarg(0), args)
        index_loc = self.rm.make_sure_var_in_reg(op.getarg(1), args)
        # 'base' and 'index' are put in two registers (or one if 'index'
        # is an immediate).  'result' can be in the same register as
        # 'index' but must be in a different register than 'base'.
        result_loc = self.force_allocate_reg(op.result, [op.getarg(0)])
        assert isinstance(result_loc, RegLoc)
        # two cases: 1) if result_loc is a normal register, use it as temp_loc
        if not result_loc.is_xmm:
            temp_loc = result_loc
        else:
            # 2) if result_loc is an xmm register, we (likely) need another
            # temp_loc that is a normal register.  It can be in the same
            # register as 'index' but not 'base'.
            tempvar = TempBox()
            temp_loc = self.rm.force_allocate_reg(tempvar, [op.getarg(0)])
            self.rm.possibly_free_var(tempvar)
        self.perform(op, [base_loc, ofs, itemsize, fieldsize,
                          index_loc, temp_loc, sign_loc], result_loc)

    def consider_int_is_true(self, op, guard_op):
        # doesn't need arg to be in a register
        argloc = self.loc(op.getarg(0))
        if guard_op is not None:
            self.perform_with_guard(op, guard_op, [argloc], None)
        else:
            resloc = self.rm.force_allocate_reg(op.result, need_lower_byte=True)
            self.perform(op, [argloc], resloc)

    consider_int_is_zero = consider_int_is_true

    def consider_same_as(self, op):
        argloc = self.loc(op.getarg(0))
        resloc = self.force_allocate_reg(op.result)
        self.perform(op, [argloc], resloc)
    consider_cast_ptr_to_int = consider_same_as
    consider_cast_int_to_ptr = consider_same_as

    def consider_int_force_ge_zero(self, op):
        argloc = self.make_sure_var_in_reg(op.getarg(0))
        resloc = self.force_allocate_reg(op.result, [op.getarg(0)])
        self.perform(op, [argloc], resloc)

    def consider_strlen(self, op):
        args = op.getarglist()
        base_loc = self.rm.make_sure_var_in_reg(op.getarg(0), args)
        result_loc = self.rm.force_allocate_reg(op.result)
        self.perform(op, [base_loc], result_loc)

    consider_unicodelen = consider_strlen

    def consider_arraylen_gc(self, op):
        arraydescr = op.getdescr()
        assert isinstance(arraydescr, ArrayDescr)
        ofs = arraydescr.lendescr.offset
        args = op.getarglist()
        base_loc = self.rm.make_sure_var_in_reg(op.getarg(0), args)
        result_loc = self.rm.force_allocate_reg(op.result)
        self.perform(op, [base_loc, imm(ofs)], result_loc)

    def consider_strgetitem(self, op):
        args = op.getarglist()
        base_loc = self.rm.make_sure_var_in_reg(op.getarg(0), args)
        ofs_loc = self.rm.make_sure_var_in_reg(op.getarg(1), args)
        result_loc = self.rm.force_allocate_reg(op.result)
        self.perform(op, [base_loc, ofs_loc], result_loc)

    consider_unicodegetitem = consider_strgetitem

    def consider_copystrcontent(self, op):
        self._consider_copystrcontent(op, is_unicode=False)

    def consider_copyunicodecontent(self, op):
        self._consider_copystrcontent(op, is_unicode=True)

    def _consider_copystrcontent(self, op, is_unicode):
        # compute the source address
        args = op.getarglist()
        base_loc = self.rm.make_sure_var_in_reg(args[0], args)
        ofs_loc = self.rm.make_sure_var_in_reg(args[2], args)
        assert args[0] is not args[1]    # forbidden case of aliasing
        srcaddr_box = TempBox()
        forbidden_vars = [args[1], args[3], args[4], srcaddr_box]
        srcaddr_loc = self.rm.force_allocate_reg(srcaddr_box, forbidden_vars)
        self._gen_address_inside_string(base_loc, ofs_loc, srcaddr_loc,
                                        is_unicode=is_unicode)
        # compute the destination address
        base_loc = self.rm.make_sure_var_in_reg(args[1], forbidden_vars)
        ofs_loc = self.rm.make_sure_var_in_reg(args[3], forbidden_vars)
        forbidden_vars = [args[4], srcaddr_box]
        dstaddr_box = TempBox()
        dstaddr_loc = self.rm.force_allocate_reg(dstaddr_box, forbidden_vars)
        self._gen_address_inside_string(base_loc, ofs_loc, dstaddr_loc,
                                        is_unicode=is_unicode)
        # compute the length in bytes
        length_box = args[4]
        length_loc = self.loc(length_box)
        if is_unicode:
            forbidden_vars = [srcaddr_box, dstaddr_box]
            bytes_box = TempBox()
            bytes_loc = self.rm.force_allocate_reg(bytes_box, forbidden_vars)
            scale = self._get_unicode_item_scale()
            if not (isinstance(length_loc, ImmedLoc) or
                    isinstance(length_loc, RegLoc)):
                self.assembler.mov(length_loc, bytes_loc)
                length_loc = bytes_loc
            self.assembler.load_effective_addr(length_loc, 0, scale, bytes_loc)
            length_box = bytes_box
            length_loc = bytes_loc
        # call memcpy()
        self.rm.before_call()
        self.xrm.before_call()
        self.assembler.simple_call_no_collect(imm(self.assembler.memcpy_addr),
                                        [dstaddr_loc, srcaddr_loc, length_loc])
        self.rm.possibly_free_var(length_box)
        self.rm.possibly_free_var(dstaddr_box)
        self.rm.possibly_free_var(srcaddr_box)

    def _gen_address_inside_string(self, baseloc, ofsloc, resloc, is_unicode):
        if is_unicode:
            ofs_items, _, _ = symbolic.get_array_token(rstr.UNICODE,
                                                  self.translate_support_code)
            scale = self._get_unicode_item_scale()
        else:
            ofs_items, itemsize, _ = symbolic.get_array_token(rstr.STR,
                                                  self.translate_support_code)
            assert itemsize == 1
            scale = 0
        self.assembler.load_effective_addr(ofsloc, ofs_items, scale,
                                           resloc, baseloc)

    def _get_unicode_item_scale(self):
        _, itemsize, _ = symbolic.get_array_token(rstr.UNICODE,
                                                  self.translate_support_code)
        if itemsize == 4:
            return 2
        elif itemsize == 2:
            return 1
        else:
            raise AssertionError("bad unicode item size")

    def consider_read_timestamp(self, op):
        tmpbox_high = TempBox()
        self.rm.force_allocate_reg(tmpbox_high, selected_reg=eax)
        if longlong.is_64_bit:
            # on 64-bit, use rax as temporary register and returns the
            # result in rdx
            result_loc = self.rm.force_allocate_reg(op.result,
                                                    selected_reg=edx)
            self.perform(op, [], result_loc)
        else:
            # on 32-bit, use both eax and edx as temporary registers,
            # use a temporary xmm register, and returns the result in
            # another xmm register.
            tmpbox_low = TempBox()
            self.rm.force_allocate_reg(tmpbox_low, selected_reg=edx)
            xmmtmpbox = TempBox()
            xmmtmploc = self.xrm.force_allocate_reg(xmmtmpbox)
            result_loc = self.xrm.force_allocate_reg(op.result)
            self.perform(op, [xmmtmploc], result_loc)
            self.xrm.possibly_free_var(xmmtmpbox)
            self.rm.possibly_free_var(tmpbox_low)
        self.rm.possibly_free_var(tmpbox_high)

    def compute_hint_frame_locations(self, operations):
        # optimization only: fill in the 'hint_frame_locations' dictionary
        # of 'fm' based on the JUMP at the end of the loop, by looking
        # at where we would like the boxes to be after the jump.
        return # XXX disabled for now
        op = operations[-1]
        if op.getopnum() != rop.JUMP:
            return
        self.final_jump_op = op
        descr = op.getdescr()
        assert isinstance(descr, TargetToken)
        if descr._ll_loop_code != 0:
            # if the target LABEL was already compiled, i.e. if it belongs
            # to some already-compiled piece of code
            self._compute_hint_frame_locations_from_descr(descr)
        #else:
        #   The loop ends in a JUMP going back to a LABEL in the same loop.
        #   We cannot fill 'hint_frame_locations' immediately, but we can
        #   wait until the corresponding consider_label() to know where the
        #   we would like the boxes to be after the jump.

    def _compute_hint_frame_locations_from_descr(self, descr):
        arglocs = descr._x86_arglocs
        jump_op = self.final_jump_op
        assert len(arglocs) == jump_op.numargs()
        for i in range(jump_op.numargs()):
            box = jump_op.getarg(i)
            if isinstance(box, Box):
                loc = arglocs[i]
                if isinstance(loc, FrameLoc):
                    self.fm.hint_frame_locations[box] = loc

    def consider_jump(self, op):
        assembler = self.assembler
        assert self.jump_target_descr is None
        descr = op.getdescr()
        assert isinstance(descr, TargetToken)
        arglocs = descr._x86_arglocs
        self.jump_target_descr = descr
        # Part about non-floats
        src_locations1 = []
        dst_locations1 = []
        # Part about floats
        src_locations2 = []
        dst_locations2 = []
        # Build the four lists
        for i in range(op.numargs()):
            box = op.getarg(i)
            src_loc = self.loc(box)
            dst_loc = arglocs[i]
            if box.type != FLOAT:
                src_locations1.append(src_loc)
                dst_locations1.append(dst_loc)
            else:
                src_locations2.append(src_loc)
                dst_locations2.append(dst_loc)
        # Do we have a temp var?
        if IS_X86_64:
            tmpreg = X86_64_SCRATCH_REG
            xmmtmp = X86_64_XMM_SCRATCH_REG
        else:
            tmpreg = None
            xmmtmp = None
        # Do the remapping
        remap_frame_layout_mixed(assembler,
                                 src_locations1, dst_locations1, tmpreg,
                                 src_locations2, dst_locations2, xmmtmp)
        self.possibly_free_vars_for_op(op)
        assembler.closing_jump(self.jump_target_descr)

    def consider_debug_merge_point(self, op):
        pass

    def consider_jit_debug(self, op):
        pass

    def _consider_force_spill(self, op):
        # This operation is used only for testing
        self.force_spill_var(op.getarg(0))

    def consider_force_token(self, op):
        # XXX for now we return a regular reg
        #self.rm.force_allocate_frame_reg(op.result)
        self.assembler.force_token(self.rm.force_allocate_reg(op.result))

    def consider_label(self, op):
        descr = op.getdescr()
        assert isinstance(descr, TargetToken)
        inputargs = op.getarglist()
        arglocs = [None] * len(inputargs)
        #
        # we use force_spill() on the boxes that are not going to be really
        # used any more in the loop, but that are kept alive anyway
        # by being in a next LABEL's or a JUMP's argument or fail_args
        # of some guard
        position = self.rm.position
        for arg in inputargs:
            assert isinstance(arg, Box)
            if self.last_real_usage.get(arg, -1) <= position:
                self.force_spill_var(arg)
        #
        # we need to make sure that no variable is stored in ebp
        for arg in inputargs:
            if self.loc(arg) is ebp:
                loc2 = self.fm.loc(arg)
                self.assembler.mc.MOV(loc2, ebp)
        self.rm.bindings_to_frame_reg.clear()
        #
        for i in range(len(inputargs)):
            arg = inputargs[i]
            assert isinstance(arg, Box)
            loc = self.loc(arg)
            assert loc is not ebp
            arglocs[i] = loc
            if isinstance(loc, RegLoc):
                self.fm.mark_as_free(arg)
        #
        # if we are too close to the start of the loop, the label's target may
        # get overridden by redirect_call_assembler().  (rare case)
        self.flush_loop()
        #
        descr._x86_arglocs = arglocs
        descr._ll_loop_code = self.assembler.mc.get_relative_pos()
        descr._x86_clt = self.assembler.current_clt
        self.assembler.target_tokens_currently_compiling[descr] = None
        self.possibly_free_vars_for_op(op)
        self.assembler.label()
        #
        # if the LABEL's descr is precisely the target of the JUMP at the
        # end of the same loop, i.e. if what we are compiling is a single
        # loop that ends up jumping to this LABEL, then we can now provide
        # the hints about the expected position of the spilled variables.

        # XXX we never compile code like that?
        # YYY of course, because compute_hint_frame_locations() is disabled.
        #     re-enable this once we re-enable it!
        #jump_op = self.final_jump_op
        #if jump_op is not None and jump_op.getdescr() is descr:
        #    self._compute_hint_frame_locations_from_descr(descr)


    def consider_keepalive(self, op):
        pass

    def not_implemented_op(self, op):
        not_implemented("not implemented operation: %s" % op.getopname())

    def not_implemented_op_with_guard(self, op, guard_op):
        not_implemented("not implemented operation with guard: %s" % (
            op.getopname(),))

oplist = [RegAlloc.not_implemented_op] * rop._LAST
oplist_with_guard = [RegAlloc.not_implemented_op_with_guard] * rop._LAST

def add_none_argument(fn):
    return lambda self, op: fn(self, op, None)

for name, value in RegAlloc.__dict__.iteritems():
    if name.startswith('consider_'):
        name = name[len('consider_'):]
        num = getattr(rop, name.upper())
        if (is_comparison_or_ovf_op(num)
            or num == rop.CALL_MAY_FORCE
            or num == rop.CALL_ASSEMBLER
            or num == rop.CALL_RELEASE_GIL):
            oplist_with_guard[num] = value
            oplist[num] = add_none_argument(value)
        else:
            oplist[num] = value

def get_ebp_ofs(base_ofs, position):
    # Argument is a frame position (0, 1, 2...).
    # Returns (ebp+20), (ebp+24), (ebp+28)...
    # i.e. the n'th word beyond the fixed frame size.
    return base_ofs + WORD * (position + JITFRAME_FIXED_SIZE)

def not_implemented(msg):
    os.write(2, '[x86/regalloc] %s\n' % msg)
    raise NotImplementedError(msg)

# xxx hack: set a default value for TargetToken._ll_loop_code.
# If 0, we know that it is a LABEL that was not compiled yet.
TargetToken._ll_loop_code = 0
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