import sys
import os

from rpython.jit.backend.llsupport import symbolic, jitframe, rewrite
from rpython.jit.backend.llsupport.assembler import (GuardToken, BaseAssembler,
                                                DEBUG_COUNTER, debug_bridge)
from rpython.jit.backend.llsupport.asmmemmgr import MachineDataBlockWrapper
from rpython.jit.backend.llsupport.gcmap import allocate_gcmap
from rpython.jit.metainterp.history import Const, Box, VOID
from rpython.jit.metainterp.history import AbstractFailDescr, INT, REF, FLOAT
from rpython.rtyper.lltypesystem import lltype, rffi, rstr, llmemory
from rpython.rtyper.lltypesystem.lloperation import llop
from rpython.rtyper.annlowlevel import llhelper, cast_instance_to_gcref
from rpython.rlib.jit import AsmInfo
from rpython.jit.backend.model import CompiledLoopToken
from rpython.jit.backend.x86.regalloc import (RegAlloc, get_ebp_ofs,
    gpr_reg_mgr_cls, xmm_reg_mgr_cls)
from rpython.jit.backend.llsupport.regalloc import (get_scale, valid_addressing_size)
from rpython.jit.backend.x86.arch import (FRAME_FIXED_SIZE, WORD, IS_X86_64,
                                       JITFRAME_FIXED_SIZE, IS_X86_32,
                                       PASS_ON_MY_FRAME)
from rpython.jit.backend.x86.regloc import (eax, ecx, edx, ebx, esp, ebp, esi,
    xmm0, xmm1, xmm2, xmm3, xmm4, xmm5, xmm6, xmm7, r8, r9, r10, r11, edi,
    r12, r13, r14, r15, X86_64_SCRATCH_REG, X86_64_XMM_SCRATCH_REG,
    RegLoc, FrameLoc, ConstFloatLoc, ImmedLoc, AddressLoc, imm,
    imm0, imm1, FloatImmedLoc, RawEbpLoc, RawEspLoc)
from rpython.rlib.objectmodel import we_are_translated
from rpython.jit.backend.x86 import rx86, codebuf, callbuilder
from rpython.jit.metainterp.resoperation import rop
from rpython.jit.backend.x86 import support
from rpython.rlib.debug import debug_print, debug_start, debug_stop
from rpython.rlib import rgc
from rpython.jit.codewriter.effectinfo import EffectInfo
from rpython.jit.codewriter import longlong
from rpython.rlib.rarithmetic import intmask, r_uint
from rpython.rlib.objectmodel import compute_unique_id


class Assembler386(BaseAssembler):
    _regalloc = None
    _output_loop_log = None
    _second_tmp_reg = ecx

    DEBUG_FRAME_DEPTH = False

    def __init__(self, cpu, translate_support_code=False):
        BaseAssembler.__init__(self, cpu, translate_support_code)
        self.verbose = False
        self.loop_run_counters = []
        self.float_const_neg_addr = 0
        self.float_const_abs_addr = 0
        self.malloc_slowpath = 0
        self.malloc_slowpath_varsize = 0
        self.wb_slowpath = [0, 0, 0, 0, 0]
        self.setup_failure_recovery()
        self.datablockwrapper = None
        self.stack_check_slowpath = 0
        self.propagate_exception_path = 0
        self.teardown()

    def setup_once(self):
        BaseAssembler.setup_once(self)
        if self.cpu.supports_floats:
            support.ensure_sse2_floats()
            self._build_float_constants()

    def setup(self, looptoken):
        assert self.memcpy_addr != 0, "setup_once() not called?"
        self.current_clt = looptoken.compiled_loop_token
        self.pending_guard_tokens = []
        if WORD == 8:
            self.pending_memoryerror_trampoline_from = []
            self.error_trampoline_64 = 0
        self.mc = codebuf.MachineCodeBlockWrapper()
        #assert self.datablockwrapper is None --- but obscure case
        # possible, e.g. getting MemoryError and continuing
        allblocks = self.get_asmmemmgr_blocks(looptoken)
        self.datablockwrapper = MachineDataBlockWrapper(self.cpu.asmmemmgr,
                                                        allblocks)
        self.target_tokens_currently_compiling = {}
        self.frame_depth_to_patch = []

    def teardown(self):
        self.pending_guard_tokens = None
        if WORD == 8:
            self.pending_memoryerror_trampoline_from = None
        self.mc = None
        self.current_clt = None

    def _build_float_constants(self):
        datablockwrapper = MachineDataBlockWrapper(self.cpu.asmmemmgr, [])
        float_constants = datablockwrapper.malloc_aligned(32, alignment=16)
        datablockwrapper.done()
        addr = rffi.cast(rffi.CArrayPtr(lltype.Char), float_constants)
        qword_padding = '\x00\x00\x00\x00\x00\x00\x00\x00'
        # 0x8000000000000000
        neg_const = '\x00\x00\x00\x00\x00\x00\x00\x80'
        # 0x7FFFFFFFFFFFFFFF
        abs_const = '\xFF\xFF\xFF\xFF\xFF\xFF\xFF\x7F'
        data = neg_const + qword_padding + abs_const + qword_padding
        for i in range(len(data)):
            addr[i] = data[i]
        self.float_const_neg_addr = float_constants
        self.float_const_abs_addr = float_constants + 16

    def set_extra_stack_depth(self, mc, value):
        if self._is_asmgcc():
            extra_ofs = self.cpu.get_ofs_of_frame_field('jf_extra_stack_depth')
            mc.MOV_bi(extra_ofs, value)

    def build_frame_realloc_slowpath(self):
        mc = codebuf.MachineCodeBlockWrapper()
        self._push_all_regs_to_frame(mc, [], self.cpu.supports_floats)
        # this is the gcmap stored by push_gcmap(mov=True) in _check_stack_frame
        mc.MOV_rs(ecx.value, WORD)
        gcmap_ofs = self.cpu.get_ofs_of_frame_field('jf_gcmap')
        mc.MOV_br(gcmap_ofs, ecx.value)

        if IS_X86_64:
            mc.MOV_rs(esi.value, WORD*2)
            # push first arg
            mc.MOV_rr(edi.value, ebp.value)
            align = callbuilder.align_stack_words(1)
            mc.SUB_ri(esp.value, (align - 1) * WORD)
        else:
            align = callbuilder.align_stack_words(3)
            mc.MOV_rs(eax.value, WORD * 2)
            mc.SUB_ri(esp.value, (align - 1) * WORD)
            mc.MOV_sr(WORD, eax.value)
            mc.MOV_sr(0, ebp.value)
        # align

        self.set_extra_stack_depth(mc, align * WORD)
        self._store_and_reset_exception(mc, None, ebx, ecx)

        mc.CALL(imm(self.cpu.realloc_frame))
        mc.MOV_rr(ebp.value, eax.value)
        self._restore_exception(mc, None, ebx, ecx)
        mc.ADD_ri(esp.value, (align - 1) * WORD)
        self.set_extra_stack_depth(mc, 0)

        gcrootmap = self.cpu.gc_ll_descr.gcrootmap
        if gcrootmap and gcrootmap.is_shadow_stack:
            self._load_shadowstack_top_in_ebx(mc, gcrootmap)
            mc.MOV_mr((ebx.value, -WORD), eax.value)

        mc.MOV_bi(gcmap_ofs, 0)
        self._pop_all_regs_from_frame(mc, [], self.cpu.supports_floats)
        mc.RET()
        self._frame_realloc_slowpath = mc.materialize(self.cpu.asmmemmgr, [])

    def _build_malloc_slowpath(self, kind):
        """ While arriving on slowpath, we have a gcpattern on stack 0.
        The arguments are passed in eax and edi, as follows:

        kind == 'fixed': nursery_head in eax and the size in edi - eax.

        kind == 'str/unicode': length of the string to allocate in edi.

        kind == 'var': length to allocate in edi, tid in eax,
                       and itemsize in the stack 1 (position esp+WORD).

        This function must preserve all registers apart from eax and edi.
        """
        assert kind in ['fixed', 'str', 'unicode', 'var']
        mc = codebuf.MachineCodeBlockWrapper()
        self._push_all_regs_to_frame(mc, [eax, edi], self.cpu.supports_floats)
        # store the gc pattern
        ofs = self.cpu.get_ofs_of_frame_field('jf_gcmap')
        mc.MOV_rs(ecx.value, WORD)
        mc.MOV_br(ofs, ecx.value)
        #
        if kind == 'fixed':
            addr = self.cpu.gc_ll_descr.get_malloc_slowpath_addr()
        elif kind == 'str':
            addr = self.cpu.gc_ll_descr.get_malloc_fn_addr('malloc_str')
        elif kind == 'unicode':
            addr = self.cpu.gc_ll_descr.get_malloc_fn_addr('malloc_unicode')
        else:
            addr = self.cpu.gc_ll_descr.get_malloc_slowpath_array_addr()
        mc.SUB_ri(esp.value, 16 - WORD)  # restore 16-byte alignment
        # magically, the above is enough on X86_32 to reserve 3 stack places
        if kind == 'fixed':
            mc.SUB_rr(edi.value, eax.value) # compute the size we want
            # the arg is already in edi
            if IS_X86_32:
                mc.MOV_sr(0, edi.value)
                if hasattr(self.cpu.gc_ll_descr, 'passes_frame'):
                    mc.MOV_sr(WORD, ebp.value)
            elif hasattr(self.cpu.gc_ll_descr, 'passes_frame'):
                # for tests only
                mc.MOV_rr(esi.value, ebp.value)
        elif kind == 'str' or kind == 'unicode':
            if IS_X86_32:
                # stack layout: [---][---][---][ret].. with 3 free stack places
                mc.MOV_sr(0, edi.value)     # store the length
            else:
                pass                        # length already in edi
        else:
            if IS_X86_32:
                # stack layout: [---][---][---][ret][gcmap][itemsize]...
                mc.MOV_sr(WORD * 2, edi.value)  # store the length
                mc.MOV_sr(WORD * 1, eax.value)  # store the tid
                mc.MOV_rs(edi.value, WORD * 5)  # load the itemsize
                mc.MOV_sr(WORD * 0, edi.value)  # store the itemsize
            else:
                # stack layout: [---][ret][gcmap][itemsize]...
                mc.MOV_rr(edx.value, edi.value) # length
                mc.MOV_rr(esi.value, eax.value) # tid
                mc.MOV_rs(edi.value, WORD * 3)  # load the itemsize
        self.set_extra_stack_depth(mc, 16)
        mc.CALL(imm(addr))
        mc.ADD_ri(esp.value, 16 - WORD)
        mc.TEST_rr(eax.value, eax.value)
        mc.J_il(rx86.Conditions['Z'], 0xfffff) # patched later
        jz_location = mc.get_relative_pos()
        #
        nursery_free_adr = self.cpu.gc_ll_descr.get_nursery_free_addr()
        self._reload_frame_if_necessary(mc, align_stack=True)
        self.set_extra_stack_depth(mc, 0)
        self._pop_all_regs_from_frame(mc, [eax, edi], self.cpu.supports_floats)
        mc.MOV(edi, heap(nursery_free_adr))   # load this in EDI
        # clear the gc pattern
        mc.MOV_bi(ofs, 0)
        mc.RET()
        #
        # If the slowpath malloc failed, we raise a MemoryError that
        # always interrupts the current loop, as a "good enough"
        # approximation.  We have to adjust the esp a little, to point to
        # the correct "ret" arg
        offset = mc.get_relative_pos() - jz_location
        mc.overwrite32(jz_location-4, offset)
        mc.ADD_ri(esp.value, WORD)
        mc.JMP(imm(self.propagate_exception_path))
        #
        rawstart = mc.materialize(self.cpu.asmmemmgr, [])
        return rawstart

    def _build_propagate_exception_path(self):
        if not self.cpu.propagate_exception_descr:
            return      # not supported (for tests, or non-translated)
        #
        self.mc = codebuf.MachineCodeBlockWrapper()
        #
        # read and reset the current exception

        self._store_and_reset_exception(self.mc, eax)
        ofs = self.cpu.get_ofs_of_frame_field('jf_guard_exc')
        self.mc.MOV_br(ofs, eax.value)
        propagate_exception_descr = rffi.cast(lltype.Signed,
                  cast_instance_to_gcref(self.cpu.propagate_exception_descr))
        ofs = self.cpu.get_ofs_of_frame_field('jf_descr')
        self.mc.MOV(RawEbpLoc(ofs), imm(propagate_exception_descr))
        self.mc.MOV_rr(eax.value, ebp.value)
        #
        self._call_footer()
        rawstart = self.mc.materialize(self.cpu.asmmemmgr, [])
        self.propagate_exception_path = rawstart
        self.mc = None

    def _build_stack_check_slowpath(self):
        _, _, slowpathaddr = self.cpu.insert_stack_check()
        if slowpathaddr == 0 or not self.cpu.propagate_exception_descr:
            return      # no stack check (for tests, or non-translated)
        #
        # make a "function" that is called immediately at the start of
        # an assembler function.  In particular, the stack looks like:
        #
        #    |  ...                |    <-- aligned to a multiple of 16
        #    |  retaddr of caller  |
        #    |  my own retaddr     |    <-- esp
        #    +---------------------+
        #
        mc = codebuf.MachineCodeBlockWrapper()
        #
        if IS_X86_64:
            # on the x86_64, we have to save all the registers that may
            # have been used to pass arguments. Note that we pass only
            # one argument, that is the frame
            mc.MOV_rr(edi.value, esp.value)
            mc.SUB_ri(esp.value, WORD)
        #
        if IS_X86_32:
            mc.SUB_ri(esp.value, 2*WORD) # alignment
            mc.PUSH_r(esp.value)
        #
        # esp is now aligned to a multiple of 16 again
        mc.CALL(imm(slowpathaddr))
        #
        if IS_X86_32:
            mc.ADD_ri(esp.value, 3*WORD)    # alignment
        else:
            mc.ADD_ri(esp.value, WORD)
        #
        mc.MOV(eax, heap(self.cpu.pos_exception()))
        mc.TEST_rr(eax.value, eax.value)
        mc.J_il8(rx86.Conditions['NZ'], 0)
        jnz_location = mc.get_relative_pos()
        #
        mc.RET()
        #
        # patch the JNZ above
        offset = mc.get_relative_pos() - jnz_location
        assert 0 < offset <= 127
        mc.overwrite(jnz_location-1, chr(offset))
        # adjust the esp to point back to the previous return
        mc.ADD_ri(esp.value, WORD)
        mc.JMP(imm(self.propagate_exception_path))
        #
        rawstart = mc.materialize(self.cpu.asmmemmgr, [])
        self.stack_check_slowpath = rawstart

    def _build_wb_slowpath(self, withcards, withfloats=False, for_frame=False):
        descr = self.cpu.gc_ll_descr.write_barrier_descr
        exc0, exc1 = None, None
        if descr is None:
            return
        if not withcards:
            func = descr.get_write_barrier_fn(self.cpu)
        else:
            if descr.jit_wb_cards_set == 0:
                return
            func = descr.get_write_barrier_from_array_fn(self.cpu)
            if func == 0:
                return
        #
        # This builds a helper function called from the slow path of
        # write barriers.  It must save all registers, and optionally
        # all XMM registers.  It takes a single argument just pushed
        # on the stack even on X86_64.  It must restore stack alignment
        # accordingly.
        mc = codebuf.MachineCodeBlockWrapper()
        #
        if not for_frame:
            self._push_all_regs_to_frame(mc, [], withfloats, callee_only=True)
            if IS_X86_32:
                # we have 2 extra words on stack for retval and we pass 1 extra
                # arg, so we need to substract 2 words
                mc.SUB_ri(esp.value, 2 * WORD)
                mc.MOV_rs(eax.value, 3 * WORD) # 2 + 1
                mc.MOV_sr(0, eax.value)
            else:
                mc.MOV_rs(edi.value, WORD)
        else:
            # we have one word to align
            mc.SUB_ri(esp.value, 7 * WORD) # align and reserve some space
            mc.MOV_sr(WORD, eax.value) # save for later
            mc.MOVSD_sx(3 * WORD, xmm0.value)
            if IS_X86_32:
                mc.MOV_sr(4 * WORD, edx.value)
                mc.MOV_sr(0, ebp.value)
                exc0, exc1 = esi, edi
            else:
                mc.MOV_rr(edi.value, ebp.value)
                exc0, exc1 = ebx, r12
            mc.MOV(RawEspLoc(WORD * 5, REF), exc0)
            mc.MOV(RawEspLoc(WORD * 6, INT), exc1)
            # note that it's save to store the exception in register,
            # since the call to write barrier can't collect
            # (and this is assumed a bit left and right here, like lack
            # of _reload_frame_if_necessary)
            self._store_and_reset_exception(mc, exc0, exc1)

        mc.CALL(imm(func))
        #
        if withcards:
            # A final TEST8 before the RET, for the caller.  Careful to
            # not follow this instruction with another one that changes
            # the status of the CPU flags!
            if IS_X86_32:
                mc.MOV_rs(eax.value, 3*WORD)
            else:
                mc.MOV_rs(eax.value, WORD)
            mc.TEST8(addr_add_const(eax, descr.jit_wb_if_flag_byteofs),
                     imm(-0x80))
        #

        if not for_frame:
            if IS_X86_32:
                # ADD touches CPU flags
                mc.LEA_rs(esp.value, 2 * WORD)
            self._pop_all_regs_from_frame(mc, [], withfloats, callee_only=True)
            mc.RET16_i(WORD)
        else:
            if IS_X86_32:
                mc.MOV_rs(edx.value, 4 * WORD)
            mc.MOVSD_xs(xmm0.value, 3 * WORD)
            mc.MOV_rs(eax.value, WORD) # restore
            self._restore_exception(mc, exc0, exc1)
            mc.MOV(exc0, RawEspLoc(WORD * 5, REF))
            mc.MOV(exc1, RawEspLoc(WORD * 6, INT))
            mc.LEA_rs(esp.value, 7 * WORD)
            mc.RET()

        rawstart = mc.materialize(self.cpu.asmmemmgr, [])
        if for_frame:
            self.wb_slowpath[4] = rawstart
        else:
            self.wb_slowpath[withcards + 2 * withfloats] = rawstart

    def assemble_loop(self, loopname, inputargs, operations, looptoken, log):
        '''adds the following attributes to looptoken:
               _ll_function_addr    (address of the generated func, as an int)
               _ll_loop_code       (debug: addr of the start of the ResOps)
               _x86_fullsize        (debug: full size including failure)
        '''
        # XXX this function is too longish and contains some code
        # duplication with assemble_bridge().  Also, we should think
        # about not storing on 'self' attributes that will live only
        # for the duration of compiling one loop or a one bridge.
        clt = CompiledLoopToken(self.cpu, looptoken.number)
        looptoken.compiled_loop_token = clt
        clt._debug_nbargs = len(inputargs)
        if not we_are_translated():
            # Arguments should be unique
            assert len(set(inputargs)) == len(inputargs)

        self.setup(looptoken)

        frame_info = self.datablockwrapper.malloc_aligned(
            jitframe.JITFRAMEINFO_SIZE, alignment=WORD)
        clt.frame_info = rffi.cast(jitframe.JITFRAMEINFOPTR, frame_info)
        clt.allgcrefs = []
        clt.frame_info.clear() # for now

        if log:
            operations = self._inject_debugging_code(looptoken, operations,
                                                     'e', looptoken.number)

        regalloc = RegAlloc(self, self.cpu.translate_support_code)
        #
        self._call_header_with_stack_check()
        self._check_frame_depth_debug(self.mc)
        operations = regalloc.prepare_loop(inputargs, operations, looptoken,
                                           clt.allgcrefs)
        looppos = self.mc.get_relative_pos()
        frame_depth_no_fixed_size = self._assemble(regalloc, inputargs,
                                                   operations)
        self.update_frame_depth(frame_depth_no_fixed_size + JITFRAME_FIXED_SIZE)
        #
        size_excluding_failure_stuff = self.mc.get_relative_pos()
        self.write_pending_failure_recoveries()
        full_size = self.mc.get_relative_pos()
        #
        rawstart = self.materialize_loop(looptoken)
        self.patch_stack_checks(frame_depth_no_fixed_size + JITFRAME_FIXED_SIZE,
                                rawstart)
        looptoken._ll_loop_code = looppos + rawstart
        debug_start("jit-backend-addr")
        debug_print("Loop %d (%s) has address 0x%x to 0x%x (bootstrap 0x%x)" % (
            looptoken.number, loopname,
            r_uint(rawstart + looppos),
            r_uint(rawstart + size_excluding_failure_stuff),
            r_uint(rawstart)))
        debug_stop("jit-backend-addr")
        self.patch_pending_failure_recoveries(rawstart)
        #
        ops_offset = self.mc.ops_offset
        if not we_are_translated():
            # used only by looptoken.dump() -- useful in tests
            looptoken._x86_rawstart = rawstart
            looptoken._x86_fullsize = full_size
            looptoken._x86_ops_offset = ops_offset
        looptoken._ll_function_addr = rawstart

        self.fixup_target_tokens(rawstart)
        self.teardown()
        # oprofile support
        if self.cpu.profile_agent is not None:
            name = "Loop # %s: %s" % (looptoken.number, loopname)
            self.cpu.profile_agent.native_code_written(name,
                                                       rawstart, full_size)
        return AsmInfo(ops_offset, rawstart + looppos,
                       size_excluding_failure_stuff - looppos)

    def assemble_bridge(self, faildescr, inputargs, operations,
                        original_loop_token, log):
        if not we_are_translated():
            # Arguments should be unique
            assert len(set(inputargs)) == len(inputargs)

        self.setup(original_loop_token)
        descr_number = compute_unique_id(faildescr)
        if log:
            operations = self._inject_debugging_code(faildescr, operations,
                                                     'b', descr_number)

        arglocs = self.rebuild_faillocs_from_descr(faildescr, inputargs)
        regalloc = RegAlloc(self, self.cpu.translate_support_code)
        startpos = self.mc.get_relative_pos()
        operations = regalloc.prepare_bridge(inputargs, arglocs,
                                             operations,
                                             self.current_clt.allgcrefs,
                                             self.current_clt.frame_info)
        self._check_frame_depth(self.mc, regalloc.get_gcmap())
        frame_depth_no_fixed_size = self._assemble(regalloc, inputargs, operations)
        codeendpos = self.mc.get_relative_pos()
        self.write_pending_failure_recoveries()
        fullsize = self.mc.get_relative_pos()
        #
        rawstart = self.materialize_loop(original_loop_token)
        self.patch_stack_checks(frame_depth_no_fixed_size + JITFRAME_FIXED_SIZE,
                                rawstart)
        debug_bridge(descr_number, rawstart, codeendpos)
        self.patch_pending_failure_recoveries(rawstart)
        # patch the jump from original guard
        self.patch_jump_for_descr(faildescr, rawstart)
        ops_offset = self.mc.ops_offset
        frame_depth = max(self.current_clt.frame_info.jfi_frame_depth,
                          frame_depth_no_fixed_size + JITFRAME_FIXED_SIZE)
        self.fixup_target_tokens(rawstart)
        self.update_frame_depth(frame_depth)
        self.teardown()
        # oprofile support
        if self.cpu.profile_agent is not None:
            name = "Bridge # %s" % (descr_number,)
            self.cpu.profile_agent.native_code_written(name,
                                                       rawstart, fullsize)
        return AsmInfo(ops_offset, startpos + rawstart, codeendpos - startpos)

    def write_pending_failure_recoveries(self):
        # for each pending guard, generate the code of the recovery stub
        # at the end of self.mc.
        for tok in self.pending_guard_tokens:
            tok.pos_recovery_stub = self.generate_quick_failure(tok)
        if WORD == 8 and len(self.pending_memoryerror_trampoline_from) > 0:
            self.error_trampoline_64 = self.generate_propagate_error_64()

    def patch_pending_failure_recoveries(self, rawstart):
        # after we wrote the assembler to raw memory, set up
        # tok.faildescr._x86_adr_jump_offset to contain the raw address of
        # the 4-byte target field in the JMP/Jcond instruction, and patch
        # the field in question to point (initially) to the recovery stub
        clt = self.current_clt
        for tok in self.pending_guard_tokens:
            addr = rawstart + tok.pos_jump_offset
            tok.faildescr._x86_adr_jump_offset = addr
            relative_target = tok.pos_recovery_stub - (tok.pos_jump_offset + 4)
            assert rx86.fits_in_32bits(relative_target)
            #
            if not tok.is_guard_not_invalidated:
                mc = codebuf.MachineCodeBlockWrapper()
                mc.writeimm32(relative_target)
                mc.copy_to_raw_memory(addr)
            else:
                # GUARD_NOT_INVALIDATED, record an entry in
                # clt.invalidate_positions of the form:
                #     (addr-in-the-code-of-the-not-yet-written-jump-target,
                #      relative-target-to-use)
                relpos = tok.pos_jump_offset
                clt.invalidate_positions.append((rawstart + relpos,
                                                 relative_target))
                # General idea: Although no code was generated by this
                # guard, the code might be patched with a "JMP rel32" to
                # the guard recovery code.  This recovery code is
                # already generated, and looks like the recovery code
                # for any guard, even if at first it has no jump to it.
                # So we may later write 5 bytes overriding the existing
                # instructions; this works because a CALL instruction
                # would also take at least 5 bytes.  If it could take
                # less, we would run into the issue that overwriting the
                # 5 bytes here might get a few nonsense bytes at the
                # return address of the following CALL.
        if WORD == 8:
            for pos_after_jz in self.pending_memoryerror_trampoline_from:
                assert self.error_trampoline_64 != 0     # only if non-empty
                mc = codebuf.MachineCodeBlockWrapper()
                mc.writeimm32(self.error_trampoline_64 - pos_after_jz)
                mc.copy_to_raw_memory(rawstart + pos_after_jz - 4)

    def update_frame_depth(self, frame_depth):
        baseofs = self.cpu.get_baseofs_of_frame_field()
        self.current_clt.frame_info.update_frame_depth(baseofs, frame_depth)

    def patch_stack_checks(self, framedepth, rawstart):
        for ofs in self.frame_depth_to_patch:
            self._patch_frame_depth(ofs + rawstart, framedepth)

    def _check_frame_depth(self, mc, gcmap, expected_size=-1):
        """ check if the frame is of enough depth to follow this bridge.
        Otherwise reallocate the frame in a helper.
        There are other potential solutions
        to that, but this one does not sound too bad.
        """
        descrs = self.cpu.gc_ll_descr.getframedescrs(self.cpu)
        ofs = self.cpu.unpack_fielddescr(descrs.arraydescr.lendescr)
        if expected_size == -1:
            mc.CMP_bi(ofs, 0xffffff)
        else:
            mc.CMP_bi(ofs, expected_size)
        stack_check_cmp_ofs = mc.get_relative_pos() - 4
        mc.J_il8(rx86.Conditions['GE'], 0)
        jg_location = mc.get_relative_pos()
        if expected_size == -1:
            mc.MOV_si(WORD, 0xffffff)
        else:
            mc.MOV_si(WORD, expected_size)
        ofs2 = mc.get_relative_pos() - 4
        self.push_gcmap(mc, gcmap, mov=True)
        mc.CALL(imm(self._frame_realloc_slowpath))
        # patch the JG above
        offset = mc.get_relative_pos() - jg_location
        assert 0 < offset <= 127
        mc.overwrite(jg_location-1, chr(offset))
        self.frame_depth_to_patch.append(stack_check_cmp_ofs)
        self.frame_depth_to_patch.append(ofs2)

    def _check_frame_depth_debug(self, mc):
        """ double check the depth size. It prints the error (and potentially
        segfaults later)
        """
        if not self.DEBUG_FRAME_DEPTH:
            return
        descrs = self.cpu.gc_ll_descr.getframedescrs(self.cpu)
        ofs = self.cpu.unpack_fielddescr(descrs.arraydescr.lendescr)
        mc.CMP_bi(ofs, 0xffffff)
        stack_check_cmp_ofs = mc.get_relative_pos() - 4
        mc.J_il8(rx86.Conditions['GE'], 0)
        jg_location = mc.get_relative_pos()
        mc.MOV_rr(edi.value, ebp.value)
        mc.MOV_ri(esi.value, 0xffffff)
        ofs2 = mc.get_relative_pos() - 4
        mc.CALL(imm(self.cpu.realloc_frame_crash))
        # patch the JG above
        offset = mc.get_relative_pos() - jg_location
        assert 0 < offset <= 127
        mc.overwrite(jg_location-1, chr(offset))
        self.frame_depth_to_patch.append(stack_check_cmp_ofs)
        self.frame_depth_to_patch.append(ofs2)

    def _patch_frame_depth(self, adr, allocated_depth):
        mc = codebuf.MachineCodeBlockWrapper()
        mc.writeimm32(allocated_depth)
        mc.copy_to_raw_memory(adr)

    def get_asmmemmgr_blocks(self, looptoken):
        clt = looptoken.compiled_loop_token
        if clt.asmmemmgr_blocks is None:
            clt.asmmemmgr_blocks = []
        return clt.asmmemmgr_blocks

    def materialize_loop(self, looptoken):
        self.datablockwrapper.done()      # finish using cpu.asmmemmgr
        self.datablockwrapper = None
        allblocks = self.get_asmmemmgr_blocks(looptoken)
        return self.mc.materialize(self.cpu.asmmemmgr, allblocks,
                                   self.cpu.gc_ll_descr.gcrootmap)

    def patch_jump_for_descr(self, faildescr, adr_new_target):
        adr_jump_offset = faildescr._x86_adr_jump_offset
        assert adr_jump_offset != 0
        offset = adr_new_target - (adr_jump_offset + 4)
        # If the new target fits within a rel32 of the jump, just patch
        # that. Otherwise, leave the original rel32 to the recovery stub in
        # place, but clobber the recovery stub with a jump to the real
        # target.
        mc = codebuf.MachineCodeBlockWrapper()
        if rx86.fits_in_32bits(offset):
            mc.writeimm32(offset)
            mc.copy_to_raw_memory(adr_jump_offset)
        else:
            # "mov r11, addr; jmp r11" is up to 13 bytes, which fits in there
            # because we always write "mov r11, imm-as-8-bytes; call *r11" in
            # the first place.
            mc.MOV_ri(X86_64_SCRATCH_REG.value, adr_new_target)
            mc.JMP_r(X86_64_SCRATCH_REG.value)
            p = rffi.cast(rffi.INTP, adr_jump_offset)
            adr_target = adr_jump_offset + 4 + rffi.cast(lltype.Signed, p[0])
            mc.copy_to_raw_memory(adr_target)
        faildescr._x86_adr_jump_offset = 0    # means "patched"

    def fixup_target_tokens(self, rawstart):
        for targettoken in self.target_tokens_currently_compiling:
            targettoken._ll_loop_code += rawstart
        self.target_tokens_currently_compiling = None

    def _assemble(self, regalloc, inputargs, operations):
        self._regalloc = regalloc
        regalloc.compute_hint_frame_locations(operations)
        regalloc.walk_operations(inputargs, operations)
        if we_are_translated() or self.cpu.dont_keepalive_stuff:
            self._regalloc = None   # else keep it around for debugging
        frame_depth = regalloc.get_final_frame_depth()
        jump_target_descr = regalloc.jump_target_descr
        if jump_target_descr is not None:
            tgt_depth = jump_target_descr._x86_clt.frame_info.jfi_frame_depth
            target_frame_depth = tgt_depth - JITFRAME_FIXED_SIZE
            frame_depth = max(frame_depth, target_frame_depth)
        return frame_depth

    def _call_header(self):
        self.mc.SUB_ri(esp.value, FRAME_FIXED_SIZE * WORD)
        self.mc.MOV_sr(PASS_ON_MY_FRAME * WORD, ebp.value)
        if IS_X86_64:
            self.mc.MOV_rr(ebp.value, edi.value)
        else:
            self.mc.MOV_rs(ebp.value, (FRAME_FIXED_SIZE + 1) * WORD)

        for i, loc in enumerate(self.cpu.CALLEE_SAVE_REGISTERS):
            self.mc.MOV_sr((PASS_ON_MY_FRAME + i + 1) * WORD, loc.value)

        gcrootmap = self.cpu.gc_ll_descr.gcrootmap
        if gcrootmap and gcrootmap.is_shadow_stack:
            self._call_header_shadowstack(gcrootmap)

    def _call_header_with_stack_check(self):
        self._call_header()
        if self.stack_check_slowpath == 0:
            pass                # no stack check (e.g. not translated)
        else:
            endaddr, lengthaddr, _ = self.cpu.insert_stack_check()
            self.mc.MOV(eax, heap(endaddr))             # MOV eax, [start]
            self.mc.SUB(eax, esp)                       # SUB eax, current
            self.mc.CMP(eax, heap(lengthaddr))          # CMP eax, [length]
            self.mc.J_il8(rx86.Conditions['BE'], 0)     # JBE .skip
            jb_location = self.mc.get_relative_pos()
            self.mc.CALL(imm(self.stack_check_slowpath))# CALL slowpath
            # patch the JB above                        # .skip:
            offset = self.mc.get_relative_pos() - jb_location
            assert 0 < offset <= 127
            self.mc.overwrite(jb_location-1, chr(offset))
            #

    def _call_footer(self):
        gcrootmap = self.cpu.gc_ll_descr.gcrootmap
        if gcrootmap and gcrootmap.is_shadow_stack:
            self._call_footer_shadowstack(gcrootmap)

        for i in range(len(self.cpu.CALLEE_SAVE_REGISTERS)-1, -1, -1):
            self.mc.MOV_rs(self.cpu.CALLEE_SAVE_REGISTERS[i].value,
                           (i + 1 + PASS_ON_MY_FRAME) * WORD)

        self.mc.MOV_rs(ebp.value, PASS_ON_MY_FRAME * WORD)
        self.mc.ADD_ri(esp.value, FRAME_FIXED_SIZE * WORD)
        self.mc.RET()

    def _load_shadowstack_top_in_ebx(self, mc, gcrootmap):
        rst = gcrootmap.get_root_stack_top_addr()
        if rx86.fits_in_32bits(rst):
            mc.MOV_rj(ebx.value, rst)            # MOV ebx, [rootstacktop]
        else:
            mc.MOV_ri(X86_64_SCRATCH_REG.value, rst) # MOV r11, rootstacktop
            mc.MOV_rm(ebx.value, (X86_64_SCRATCH_REG.value, 0))
            # MOV ebx, [r11]
        #
        return rst

    def _call_header_shadowstack(self, gcrootmap):
        rst = self._load_shadowstack_top_in_ebx(self.mc, gcrootmap)
        self.mc.MOV_mr((ebx.value, 0), ebp.value)      # MOV [ebx], ebp
        self.mc.ADD_ri(ebx.value, WORD)
        if rx86.fits_in_32bits(rst):
            self.mc.MOV_jr(rst, ebx.value)            # MOV [rootstacktop], ebx
        else:
            self.mc.MOV_mr((X86_64_SCRATCH_REG.value, 0),
                           ebx.value) # MOV [r11], ebx

    def _call_footer_shadowstack(self, gcrootmap):
        rst = gcrootmap.get_root_stack_top_addr()
        if rx86.fits_in_32bits(rst):
            self.mc.SUB_ji8(rst, WORD)       # SUB [rootstacktop], WORD
        else:
            self.mc.MOV_ri(ebx.value, rst)           # MOV ebx, rootstacktop
            self.mc.SUB_mi8((ebx.value, 0), WORD)  # SUB [ebx], WORD

    def redirect_call_assembler(self, oldlooptoken, newlooptoken):
        # some minimal sanity checking
        old_nbargs = oldlooptoken.compiled_loop_token._debug_nbargs
        new_nbargs = newlooptoken.compiled_loop_token._debug_nbargs
        assert old_nbargs == new_nbargs
        # we overwrite the instructions at the old _ll_function_addr
        # to start with a JMP to the new _ll_function_addr.
        # Ideally we should rather patch all existing CALLs, but well.
        oldadr = oldlooptoken._ll_function_addr
        target = newlooptoken._ll_function_addr
        # copy frame-info data
        baseofs = self.cpu.get_baseofs_of_frame_field()
        newlooptoken.compiled_loop_token.update_frame_info(
            oldlooptoken.compiled_loop_token, baseofs)
        mc = codebuf.MachineCodeBlockWrapper()
        mc.JMP(imm(target))
        if WORD == 4:         # keep in sync with prepare_loop()
            assert mc.get_relative_pos() == 5
        else:
            assert mc.get_relative_pos() <= 13
        mc.copy_to_raw_memory(oldadr)

    def dump(self, text):
        if not self.verbose:
            return
        _prev = Box._extended_display
        try:
            Box._extended_display = False
            pos = self.mc.get_relative_pos()
            print >> sys.stderr, ' 0x%x  %s' % (pos, text)
        finally:
            Box._extended_display = _prev

    # ------------------------------------------------------------

    def mov(self, from_loc, to_loc):
        if (isinstance(from_loc, RegLoc) and from_loc.is_xmm) or (isinstance(to_loc, RegLoc) and to_loc.is_xmm):
            self.mc.MOVSD(to_loc, from_loc)
        else:
            assert to_loc is not ebp
            self.mc.MOV(to_loc, from_loc)

    regalloc_mov = mov # legacy interface

    def regalloc_push(self, loc):
        if isinstance(loc, RegLoc) and loc.is_xmm:
            self.mc.SUB_ri(esp.value, 8)   # = size of doubles
            self.mc.MOVSD_sx(0, loc.value)
        elif WORD == 4 and isinstance(loc, FrameLoc) and loc.get_width() == 8:
            # XXX evil trick
            self.mc.PUSH_b(loc.value + 4)
            self.mc.PUSH_b(loc.value)
        else:
            self.mc.PUSH(loc)

    def regalloc_pop(self, loc):
        if isinstance(loc, RegLoc) and loc.is_xmm:
            self.mc.MOVSD_xs(loc.value, 0)
            self.mc.ADD_ri(esp.value, 8)   # = size of doubles
        elif WORD == 4 and isinstance(loc, FrameLoc) and loc.get_width() == 8:
            # XXX evil trick
            self.mc.POP_b(loc.value)
            self.mc.POP_b(loc.value + 4)
        else:
            self.mc.POP(loc)

    def regalloc_immedmem2mem(self, from_loc, to_loc):
        # move a ConstFloatLoc directly to a FrameLoc, as two MOVs
        # (even on x86-64, because the immediates are encoded as 32 bits)
        assert isinstance(from_loc, ConstFloatLoc)
        low_part  = rffi.cast(rffi.CArrayPtr(rffi.INT), from_loc.value)[0]
        high_part = rffi.cast(rffi.CArrayPtr(rffi.INT), from_loc.value)[1]
        low_part  = intmask(low_part)
        high_part = intmask(high_part)
        if isinstance(to_loc, RawEbpLoc):
            self.mc.MOV32_bi(to_loc.value,     low_part)
            self.mc.MOV32_bi(to_loc.value + 4, high_part)
        else:
            assert isinstance(to_loc, RawEspLoc)
            self.mc.MOV32_si(to_loc.value,     low_part)
            self.mc.MOV32_si(to_loc.value + 4, high_part)

    def regalloc_perform(self, op, arglocs, resloc):
        genop_list[op.getopnum()](self, op, arglocs, resloc)

    def regalloc_perform_discard(self, op, arglocs):
        genop_discard_list[op.getopnum()](self, op, arglocs)

    def regalloc_perform_llong(self, op, arglocs, resloc):
        effectinfo = op.getdescr().get_extra_info()
        oopspecindex = effectinfo.oopspecindex
        genop_llong_list[oopspecindex](self, op, arglocs, resloc)

    def regalloc_perform_math(self, op, arglocs, resloc):
        effectinfo = op.getdescr().get_extra_info()
        oopspecindex = effectinfo.oopspecindex
        genop_math_list[oopspecindex](self, op, arglocs, resloc)

    def regalloc_perform_with_guard(self, op, guard_op, faillocs,
                                    arglocs, resloc, frame_depth):
        faildescr = guard_op.getdescr()
        assert isinstance(faildescr, AbstractFailDescr)
        failargs = guard_op.getfailargs()
        guard_opnum = guard_op.getopnum()
        guard_token = self.implement_guard_recovery(guard_opnum,
                                                    faildescr, failargs,
                                                    faillocs, frame_depth)
        if op is None:
            dispatch_opnum = guard_opnum
        else:
            dispatch_opnum = op.getopnum()
        genop_guard_list[dispatch_opnum](self, op, guard_op, guard_token,
                                         arglocs, resloc)
        if not we_are_translated():
            # must be added by the genop_guard_list[]()
            assert guard_token is self.pending_guard_tokens[-1]

    def regalloc_perform_guard(self, guard_op, faillocs, arglocs, resloc,
                               frame_depth):
        self.regalloc_perform_with_guard(None, guard_op, faillocs, arglocs,
                                         resloc, frame_depth)

    def load_effective_addr(self, sizereg, baseofs, scale, result, frm=imm0):
        self.mc.LEA(result, addr_add(frm, sizereg, baseofs, scale))

    def _unaryop(asmop):
        def genop_unary(self, op, arglocs, resloc):
            getattr(self.mc, asmop)(arglocs[0])
        return genop_unary

    def _binaryop(asmop, can_swap=False):
        def genop_binary(self, op, arglocs, result_loc):
            getattr(self.mc, asmop)(arglocs[0], arglocs[1])
        return genop_binary

    def _binaryop_or_lea(asmop, is_add):
        def genop_binary_or_lea(self, op, arglocs, result_loc):
            # use a regular ADD or SUB if result_loc is arglocs[0],
            # and a LEA only if different.
            if result_loc is arglocs[0]:
                getattr(self.mc, asmop)(arglocs[0], arglocs[1])
            else:
                loc = arglocs[0]
                argloc = arglocs[1]
                assert isinstance(loc, RegLoc)
                assert isinstance(argloc, ImmedLoc)
                assert isinstance(result_loc, RegLoc)
                delta = argloc.value
                if not is_add:    # subtraction
                    delta = -delta
                self.mc.LEA_rm(result_loc.value, (loc.value, delta))
        return genop_binary_or_lea

    def _cmpop(cond, rev_cond):
        def genop_cmp(self, op, arglocs, result_loc):
            rl = result_loc.lowest8bits()
            if isinstance(op.getarg(0), Const):
                self.mc.CMP(arglocs[1], arglocs[0])
                self.mc.SET_ir(rx86.Conditions[rev_cond], rl.value)
            else:
                self.mc.CMP(arglocs[0], arglocs[1])
                self.mc.SET_ir(rx86.Conditions[cond], rl.value)
            self.mc.MOVZX8_rr(result_loc.value, rl.value)
        return genop_cmp

    def _cmpop_float(cond, rev_cond, is_ne=False):
        def genop_cmp(self, op, arglocs, result_loc):
            if isinstance(arglocs[0], RegLoc):
                self.mc.UCOMISD(arglocs[0], arglocs[1])
                checkcond = cond
            else:
                self.mc.UCOMISD(arglocs[1], arglocs[0])
                checkcond = rev_cond

            tmp1 = result_loc.lowest8bits()
            if IS_X86_32:
                tmp2 = result_loc.higher8bits()
            elif IS_X86_64:
                tmp2 = X86_64_SCRATCH_REG.lowest8bits()

            self.mc.SET_ir(rx86.Conditions[checkcond], tmp1.value)
            if is_ne:
                self.mc.SET_ir(rx86.Conditions['P'], tmp2.value)
                self.mc.OR8_rr(tmp1.value, tmp2.value)
            else:
                self.mc.SET_ir(rx86.Conditions['NP'], tmp2.value)
                self.mc.AND8_rr(tmp1.value, tmp2.value)
            self.mc.MOVZX8_rr(result_loc.value, tmp1.value)
        return genop_cmp

    def _cmpop_guard(cond, rev_cond, false_cond, false_rev_cond):
        def genop_cmp_guard(self, op, guard_op, guard_token, arglocs, result_loc):
            guard_opnum = guard_op.getopnum()
            if isinstance(op.getarg(0), Const):
                self.mc.CMP(arglocs[1], arglocs[0])
                if guard_opnum == rop.GUARD_FALSE:
                    self.implement_guard(guard_token, rev_cond)
                else:
                    self.implement_guard(guard_token, false_rev_cond)
            else:
                self.mc.CMP(arglocs[0], arglocs[1])
                if guard_opnum == rop.GUARD_FALSE:
                    self.implement_guard(guard_token, cond)
                else:
                    self.implement_guard(guard_token, false_cond)
        return genop_cmp_guard

    def _cmpop_guard_float(cond, rev_cond, false_cond, false_rev_cond):
        need_direct_jp = 'A' not in cond
        need_rev_jp = 'A' not in rev_cond
        def genop_cmp_guard_float(self, op, guard_op, guard_token, arglocs,
                                  result_loc):
            guard_opnum = guard_op.getopnum()
            if isinstance(arglocs[0], RegLoc):
                self.mc.UCOMISD(arglocs[0], arglocs[1])
                checkcond = cond
                checkfalsecond = false_cond
                need_jp = need_direct_jp
            else:
                self.mc.UCOMISD(arglocs[1], arglocs[0])
                checkcond = rev_cond
                checkfalsecond = false_rev_cond
                need_jp = need_rev_jp
            if guard_opnum == rop.GUARD_FALSE:
                if need_jp:
                    self.mc.J_il8(rx86.Conditions['P'], 6)
                self.implement_guard(guard_token, checkcond)
            else:
                if need_jp:
                    self.mc.J_il8(rx86.Conditions['P'], 2)
                    self.mc.J_il8(rx86.Conditions[checkcond], 5)
                    self.implement_guard(guard_token)
                else:
                    self.implement_guard(guard_token, checkfalsecond)
        return genop_cmp_guard_float

    def simple_call(self, fnloc, arglocs, result_loc=eax):
        if result_loc is xmm0:
            result_type = FLOAT
            result_size = 8
        elif result_loc is None:
            result_type = VOID
            result_size = 0
        else:
            result_type = INT
            result_size = WORD
        cb = callbuilder.CallBuilder(self, fnloc, arglocs,
                                     result_loc, result_type,
                                     result_size)
        cb.emit()

    def simple_call_no_collect(self, fnloc, arglocs):
        cb = callbuilder.CallBuilder(self, fnloc, arglocs)
        cb.emit_no_collect()

    def _reload_frame_if_necessary(self, mc, align_stack=False):
        gcrootmap = self.cpu.gc_ll_descr.gcrootmap
        if gcrootmap:
            if gcrootmap.is_shadow_stack:
                rst = gcrootmap.get_root_stack_top_addr()
                mc.MOV(ecx, heap(rst))
                mc.MOV(ebp, mem(ecx, -WORD))
        wbdescr = self.cpu.gc_ll_descr.write_barrier_descr
        if gcrootmap and wbdescr:
            # frame never uses card marking, so we enforce this is not
            # an array
            self._write_barrier_fastpath(mc, wbdescr, [ebp], array=False,
                                         is_frame=True, align_stack=align_stack)

    genop_int_neg = _unaryop("NEG")
    genop_int_invert = _unaryop("NOT")
    genop_int_add = _binaryop_or_lea("ADD", True)
    genop_int_sub = _binaryop_or_lea("SUB", False)
    genop_int_mul = _binaryop("IMUL", True)
    genop_int_and = _binaryop("AND", True)
    genop_int_or  = _binaryop("OR", True)
    genop_int_xor = _binaryop("XOR", True)
    genop_int_lshift = _binaryop("SHL")
    genop_int_rshift = _binaryop("SAR")
    genop_uint_rshift = _binaryop("SHR")
    genop_float_add = _binaryop("ADDSD", True)
    genop_float_sub = _binaryop('SUBSD')
    genop_float_mul = _binaryop('MULSD', True)
    genop_float_truediv = _binaryop('DIVSD')

    genop_int_lt = _cmpop("L", "G")
    genop_int_le = _cmpop("LE", "GE")
    genop_int_eq = _cmpop("E", "E")
    genop_int_ne = _cmpop("NE", "NE")
    genop_int_gt = _cmpop("G", "L")
    genop_int_ge = _cmpop("GE", "LE")
    genop_ptr_eq = genop_instance_ptr_eq = genop_int_eq
    genop_ptr_ne = genop_instance_ptr_ne = genop_int_ne

    genop_float_lt = _cmpop_float('B', 'A')
    genop_float_le = _cmpop_float('BE', 'AE')
    genop_float_ne = _cmpop_float('NE', 'NE', is_ne=True)
    genop_float_eq = _cmpop_float('E', 'E')
    genop_float_gt = _cmpop_float('A', 'B')
    genop_float_ge = _cmpop_float('AE', 'BE')

    genop_uint_gt = _cmpop("A", "B")
    genop_uint_lt = _cmpop("B", "A")
    genop_uint_le = _cmpop("BE", "AE")
    genop_uint_ge = _cmpop("AE", "BE")

    genop_guard_int_lt = _cmpop_guard("L", "G", "GE", "LE")
    genop_guard_int_le = _cmpop_guard("LE", "GE", "G", "L")
    genop_guard_int_eq = _cmpop_guard("E", "E", "NE", "NE")
    genop_guard_int_ne = _cmpop_guard("NE", "NE", "E", "E")
    genop_guard_int_gt = _cmpop_guard("G", "L", "LE", "GE")
    genop_guard_int_ge = _cmpop_guard("GE", "LE", "L", "G")
    genop_guard_ptr_eq = genop_guard_instance_ptr_eq = genop_guard_int_eq
    genop_guard_ptr_ne = genop_guard_instance_ptr_ne = genop_guard_int_ne

    genop_guard_uint_gt = _cmpop_guard("A", "B", "BE", "AE")
    genop_guard_uint_lt = _cmpop_guard("B", "A", "AE", "BE")
    genop_guard_uint_le = _cmpop_guard("BE", "AE", "A", "B")
    genop_guard_uint_ge = _cmpop_guard("AE", "BE", "B", "A")

    genop_guard_float_lt = _cmpop_guard_float("B", "A", "AE","BE")
    genop_guard_float_le = _cmpop_guard_float("BE","AE", "A", "B")
    genop_guard_float_eq = _cmpop_guard_float("E", "E", "NE","NE")
    genop_guard_float_gt = _cmpop_guard_float("A", "B", "BE","AE")
    genop_guard_float_ge = _cmpop_guard_float("AE","BE", "B", "A")

    def genop_math_sqrt(self, op, arglocs, resloc):
        self.mc.SQRTSD(arglocs[0], resloc)

    def genop_guard_float_ne(self, op, guard_op, guard_token, arglocs, result_loc):
        guard_opnum = guard_op.getopnum()
        if isinstance(arglocs[0], RegLoc):
            self.mc.UCOMISD(arglocs[0], arglocs[1])
        else:
            self.mc.UCOMISD(arglocs[1], arglocs[0])
        if guard_opnum == rop.GUARD_TRUE:
            self.mc.J_il8(rx86.Conditions['P'], 6)
            self.implement_guard(guard_token, 'E')
        else:
            self.mc.J_il8(rx86.Conditions['P'], 2)
            self.mc.J_il8(rx86.Conditions['E'], 5)
            self.implement_guard(guard_token)

    def genop_float_neg(self, op, arglocs, resloc):
        # Following what gcc does: res = x ^ 0x8000000000000000
        self.mc.XORPD(arglocs[0], heap(self.float_const_neg_addr))

    def genop_float_abs(self, op, arglocs, resloc):
        # Following what gcc does: res = x & 0x7FFFFFFFFFFFFFFF
        self.mc.ANDPD(arglocs[0], heap(self.float_const_abs_addr))

    def genop_cast_float_to_int(self, op, arglocs, resloc):
        self.mc.CVTTSD2SI(resloc, arglocs[0])

    def genop_cast_int_to_float(self, op, arglocs, resloc):
        self.mc.CVTSI2SD(resloc, arglocs[0])

    def genop_cast_float_to_singlefloat(self, op, arglocs, resloc):
        loc0, loctmp = arglocs
        self.mc.CVTSD2SS(loctmp, loc0)
        assert isinstance(resloc, RegLoc)
        assert isinstance(loctmp, RegLoc)
        self.mc.MOVD_rx(resloc.value, loctmp.value)

    def genop_cast_singlefloat_to_float(self, op, arglocs, resloc):
        loc0, = arglocs
        assert isinstance(resloc, RegLoc)
        assert isinstance(loc0, RegLoc)
        self.mc.MOVD_xr(resloc.value, loc0.value)
        self.mc.CVTSS2SD_xx(resloc.value, resloc.value)

    def genop_convert_float_bytes_to_longlong(self, op, arglocs, resloc):
        loc0, = arglocs
        if longlong.is_64_bit:
            assert isinstance(resloc, RegLoc)
            assert isinstance(loc0, RegLoc)
            self.mc.MOVD(resloc, loc0)
        else:
            self.mov(loc0, resloc)

    def genop_convert_longlong_bytes_to_float(self, op, arglocs, resloc):
        loc0, = arglocs
        if longlong.is_64_bit:
            assert isinstance(resloc, RegLoc)
            assert isinstance(loc0, RegLoc)
            self.mc.MOVD(resloc, loc0)
        else:
            self.mov(loc0, resloc)

    def genop_guard_int_is_true(self, op, guard_op, guard_token, arglocs, resloc):
        guard_opnum = guard_op.getopnum()
        self.mc.CMP(arglocs[0], imm0)
        if guard_opnum == rop.GUARD_TRUE:
            self.implement_guard(guard_token, 'Z')
        else:
            self.implement_guard(guard_token, 'NZ')

    def genop_int_is_true(self, op, arglocs, resloc):
        self.mc.CMP(arglocs[0], imm0)
        rl = resloc.lowest8bits()
        self.mc.SET_ir(rx86.Conditions['NE'], rl.value)
        self.mc.MOVZX8(resloc, rl)

    def genop_guard_int_is_zero(self, op, guard_op, guard_token, arglocs, resloc):
        guard_opnum = guard_op.getopnum()
        self.mc.CMP(arglocs[0], imm0)
        if guard_opnum == rop.GUARD_TRUE:
            self.implement_guard(guard_token, 'NZ')
        else:
            self.implement_guard(guard_token, 'Z')

    def genop_int_is_zero(self, op, arglocs, resloc):
        self.mc.CMP(arglocs[0], imm0)
        rl = resloc.lowest8bits()
        self.mc.SET_ir(rx86.Conditions['E'], rl.value)
        self.mc.MOVZX8(resloc, rl)

    def genop_same_as(self, op, arglocs, resloc):
        self.mov(arglocs[0], resloc)
    genop_cast_ptr_to_int = genop_same_as
    genop_cast_int_to_ptr = genop_same_as

    def genop_int_force_ge_zero(self, op, arglocs, resloc):
        self.mc.TEST(arglocs[0], arglocs[0])
        self.mov(imm0, resloc)
        self.mc.CMOVNS(resloc, arglocs[0])

    def genop_int_mod(self, op, arglocs, resloc):
        if IS_X86_32:
            self.mc.CDQ()
        elif IS_X86_64:
            self.mc.CQO()

        self.mc.IDIV_r(ecx.value)

    genop_int_floordiv = genop_int_mod

    def genop_uint_floordiv(self, op, arglocs, resloc):
        self.mc.XOR_rr(edx.value, edx.value)
        self.mc.DIV_r(ecx.value)

    genop_llong_add = _binaryop("PADDQ", True)
    genop_llong_sub = _binaryop("PSUBQ")
    genop_llong_and = _binaryop("PAND",  True)
    genop_llong_or  = _binaryop("POR",   True)
    genop_llong_xor = _binaryop("PXOR",  True)

    def genop_llong_to_int(self, op, arglocs, resloc):
        loc = arglocs[0]
        assert isinstance(resloc, RegLoc)
        if isinstance(loc, RegLoc):
            self.mc.MOVD_rx(resloc.value, loc.value)
        elif isinstance(loc, FrameLoc):
            self.mc.MOV_rb(resloc.value, loc.value)
        else:
            not_implemented("llong_to_int: %s" % (loc,))

    def genop_llong_from_int(self, op, arglocs, resloc):
        loc1, loc2 = arglocs
        if isinstance(loc1, ConstFloatLoc):
            assert loc2 is None
            self.mc.MOVSD(resloc, loc1)
        else:
            assert isinstance(loc1, RegLoc)
            assert isinstance(loc2, RegLoc)
            assert isinstance(resloc, RegLoc)
            self.mc.MOVD_xr(loc2.value, loc1.value)
            self.mc.PSRAD_xi(loc2.value, 31)    # -> 0 or -1
            self.mc.MOVD_xr(resloc.value, loc1.value)
            self.mc.PUNPCKLDQ_xx(resloc.value, loc2.value)

    def genop_llong_from_uint(self, op, arglocs, resloc):
        loc1, = arglocs
        assert isinstance(resloc, RegLoc)
        assert isinstance(loc1, RegLoc)
        self.mc.MOVD_xr(resloc.value, loc1.value)

    def genop_llong_eq(self, op, arglocs, resloc):
        loc1, loc2, locxtmp = arglocs
        self.mc.MOVSD(locxtmp, loc1)
        self.mc.PCMPEQD(locxtmp, loc2)
        self.mc.PMOVMSKB_rx(resloc.value, locxtmp.value)
        # Now the lower 8 bits of resloc contain 0x00, 0x0F, 0xF0 or 0xFF
        # depending on the result of the comparison of each of the two
        # double-words of loc1 and loc2.  The higher 8 bits contain random
        # results.  We want to map 0xFF to 1, and 0x00, 0x0F and 0xF0 to 0.
        self.mc.CMP8_ri(resloc.value | rx86.BYTE_REG_FLAG, -1)
        self.mc.SBB_rr(resloc.value, resloc.value)
        self.mc.ADD_ri(resloc.value, 1)

    def genop_llong_ne(self, op, arglocs, resloc):
        loc1, loc2, locxtmp = arglocs
        self.mc.MOVSD(locxtmp, loc1)
        self.mc.PCMPEQD(locxtmp, loc2)
        self.mc.PMOVMSKB_rx(resloc.value, locxtmp.value)
        # Now the lower 8 bits of resloc contain 0x00, 0x0F, 0xF0 or 0xFF
        # depending on the result of the comparison of each of the two
        # double-words of loc1 and loc2.  The higher 8 bits contain random
        # results.  We want to map 0xFF to 0, and 0x00, 0x0F and 0xF0 to 1.
        self.mc.CMP8_ri(resloc.value | rx86.BYTE_REG_FLAG, -1)
        self.mc.SBB_rr(resloc.value, resloc.value)
        self.mc.NEG_r(resloc.value)

    def genop_llong_lt(self, op, arglocs, resloc):
        # XXX just a special case for now: "x < 0"
        loc1, = arglocs
        self.mc.PMOVMSKB_rx(resloc.value, loc1.value)
        self.mc.SHR_ri(resloc.value, 7)
        self.mc.AND_ri(resloc.value, 1)

    # ----------

    def genop_call_malloc_gc(self, op, arglocs, result_loc):
        self._genop_call(op, arglocs, result_loc)
        self.propagate_memoryerror_if_eax_is_null()

    def propagate_memoryerror_if_eax_is_null(self):
        # if self.propagate_exception_path == 0 (tests), this may jump to 0
        # and segfaults.  too bad.  the alternative is to continue anyway
        # with eax==0, but that will segfault too.
        self.mc.TEST_rr(eax.value, eax.value)
        if WORD == 4:
            self.mc.J_il(rx86.Conditions['Z'], self.propagate_exception_path)
            self.mc.add_pending_relocation()
        elif WORD == 8:
            self.mc.J_il(rx86.Conditions['Z'], 0)
            pos = self.mc.get_relative_pos()
            self.pending_memoryerror_trampoline_from.append(pos)

    # ----------

    def load_from_mem(self, resloc, source_addr, size_loc, sign_loc):
        assert isinstance(resloc, RegLoc)
        size = size_loc.value
        sign = sign_loc.value
        if resloc.is_xmm:
            self.mc.MOVSD(resloc, source_addr)
        elif size == WORD:
            self.mc.MOV(resloc, source_addr)
        elif size == 1:
            if sign:
                self.mc.MOVSX8(resloc, source_addr)
            else:
                self.mc.MOVZX8(resloc, source_addr)
        elif size == 2:
            if sign:
                self.mc.MOVSX16(resloc, source_addr)
            else:
                self.mc.MOVZX16(resloc, source_addr)
        elif IS_X86_64 and size == 4:
            if sign:
                self.mc.MOVSX32(resloc, source_addr)
            else:
                self.mc.MOV32(resloc, source_addr)    # zero-extending
        else:
            not_implemented("load_from_mem size = %d" % size)

    def save_into_mem(self, dest_addr, value_loc, size_loc):
        size = size_loc.value
        if isinstance(value_loc, RegLoc) and value_loc.is_xmm:
            self.mc.MOVSD(dest_addr, value_loc)
        elif size == 1:
            self.mc.MOV8(dest_addr, value_loc.lowest8bits())
        elif size == 2:
            self.mc.MOV16(dest_addr, value_loc)
        elif size == 4:
            self.mc.MOV32(dest_addr, value_loc)
        elif size == 8:
            if IS_X86_64:
                self.mc.MOV(dest_addr, value_loc)
            else:
                assert isinstance(value_loc, FloatImmedLoc)
                self.mc.MOV(dest_addr, value_loc.low_part_loc())
                self.mc.MOV(dest_addr.add_offset(4), value_loc.high_part_loc())
        else:
            not_implemented("save_into_mem size = %d" % size)

    def genop_getfield_gc(self, op, arglocs, resloc):
        base_loc, ofs_loc, size_loc, sign_loc = arglocs
        assert isinstance(size_loc, ImmedLoc)
        source_addr = AddressLoc(base_loc, ofs_loc)
        self.load_from_mem(resloc, source_addr, size_loc, sign_loc)

    genop_getfield_raw = genop_getfield_gc
    genop_getfield_raw_pure = genop_getfield_gc
    genop_getfield_gc_pure = genop_getfield_gc

    def genop_getarrayitem_gc(self, op, arglocs, resloc):
        base_loc, ofs_loc, size_loc, ofs, sign_loc = arglocs
        assert isinstance(ofs, ImmedLoc)
        assert isinstance(size_loc, ImmedLoc)
        scale = get_scale(size_loc.value)
        src_addr = addr_add(base_loc, ofs_loc, ofs.value, scale)
        self.load_from_mem(resloc, src_addr, size_loc, sign_loc)

    genop_getarrayitem_gc_pure = genop_getarrayitem_gc
    genop_getarrayitem_raw = genop_getarrayitem_gc
    genop_getarrayitem_raw_pure = genop_getarrayitem_gc

    def genop_raw_load(self, op, arglocs, resloc):
        base_loc, ofs_loc, size_loc, ofs, sign_loc = arglocs
        assert isinstance(ofs, ImmedLoc)
        src_addr = addr_add(base_loc, ofs_loc, ofs.value, 0)
        self.load_from_mem(resloc, src_addr, size_loc, sign_loc)

    def _imul_const_scaled(self, mc, targetreg, sourcereg, itemsize):
        """Produce one operation to do roughly
               targetreg = sourcereg * itemsize
           except that the targetreg may still need shifting by 0,1,2,3.
        """
        if (itemsize & 7) == 0:
            shift = 3
        elif (itemsize & 3) == 0:
            shift = 2
        elif (itemsize & 1) == 0:
            shift = 1
        else:
            shift = 0
        itemsize >>= shift
        #
        if valid_addressing_size(itemsize - 1):
            mc.LEA_ra(targetreg, (sourcereg, sourcereg,
                                  get_scale(itemsize - 1), 0))
        elif valid_addressing_size(itemsize):
            mc.LEA_ra(targetreg, (rx86.NO_BASE_REGISTER, sourcereg,
                                  get_scale(itemsize), 0))
        else:
            mc.IMUL_rri(targetreg, sourcereg, itemsize)
        #
        return shift

    def _get_interiorfield_addr(self, temp_loc, index_loc, itemsize_loc,
                                base_loc, ofs_loc):
        assert isinstance(itemsize_loc, ImmedLoc)
        itemsize = itemsize_loc.value
        if isinstance(index_loc, ImmedLoc):
            temp_loc = imm(index_loc.value * itemsize)
            shift = 0
        elif valid_addressing_size(itemsize):
            temp_loc = index_loc
            shift = get_scale(itemsize)
        else:
            assert isinstance(index_loc, RegLoc)
            assert isinstance(temp_loc, RegLoc)
            assert not temp_loc.is_xmm
            shift = self._imul_const_scaled(self.mc, temp_loc.value,
                                            index_loc.value, itemsize)
        assert isinstance(ofs_loc, ImmedLoc)
        return AddressLoc(base_loc, temp_loc, shift, ofs_loc.value)

    def genop_getinteriorfield_gc(self, op, arglocs, resloc):
        (base_loc, ofs_loc, itemsize_loc, fieldsize_loc,
            index_loc, temp_loc, sign_loc) = arglocs
        src_addr = self._get_interiorfield_addr(temp_loc, index_loc,
                                                itemsize_loc, base_loc,
                                                ofs_loc)
        self.load_from_mem(resloc, src_addr, fieldsize_loc, sign_loc)

    def genop_discard_setfield_gc(self, op, arglocs):
        base_loc, ofs_loc, size_loc, value_loc = arglocs
        assert isinstance(size_loc, ImmedLoc)
        dest_addr = AddressLoc(base_loc, ofs_loc)
        self.save_into_mem(dest_addr, value_loc, size_loc)

    def genop_discard_setinteriorfield_gc(self, op, arglocs):
        (base_loc, ofs_loc, itemsize_loc, fieldsize_loc,
            index_loc, temp_loc, value_loc) = arglocs
        dest_addr = self._get_interiorfield_addr(temp_loc, index_loc,
                                                 itemsize_loc, base_loc,
                                                 ofs_loc)
        self.save_into_mem(dest_addr, value_loc, fieldsize_loc)

    genop_discard_setinteriorfield_raw = genop_discard_setinteriorfield_gc

    def genop_discard_setarrayitem_gc(self, op, arglocs):
        base_loc, ofs_loc, value_loc, size_loc, baseofs = arglocs
        assert isinstance(baseofs, ImmedLoc)
        assert isinstance(size_loc, ImmedLoc)
        scale = get_scale(size_loc.value)
        dest_addr = AddressLoc(base_loc, ofs_loc, scale, baseofs.value)
        self.save_into_mem(dest_addr, value_loc, size_loc)

    def genop_discard_raw_store(self, op, arglocs):
        base_loc, ofs_loc, value_loc, size_loc, baseofs = arglocs
        assert isinstance(baseofs, ImmedLoc)
        dest_addr = AddressLoc(base_loc, ofs_loc, 0, baseofs.value)
        self.save_into_mem(dest_addr, value_loc, size_loc)

    def genop_discard_strsetitem(self, op, arglocs):
        base_loc, ofs_loc, val_loc = arglocs
        basesize, itemsize, ofs_length = symbolic.get_array_token(rstr.STR,
                                              self.cpu.translate_support_code)
        assert itemsize == 1
        dest_addr = AddressLoc(base_loc, ofs_loc, 0, basesize)
        self.mc.MOV8(dest_addr, val_loc.lowest8bits())

    def genop_discard_unicodesetitem(self, op, arglocs):
        base_loc, ofs_loc, val_loc = arglocs
        basesize, itemsize, ofs_length = symbolic.get_array_token(rstr.UNICODE,
                                              self.cpu.translate_support_code)
        if itemsize == 4:
            self.mc.MOV32(AddressLoc(base_loc, ofs_loc, 2, basesize), val_loc)
        elif itemsize == 2:
            self.mc.MOV16(AddressLoc(base_loc, ofs_loc, 1, basesize), val_loc)
        else:
            assert 0, itemsize

    genop_discard_setfield_raw = genop_discard_setfield_gc
    genop_discard_setarrayitem_raw = genop_discard_setarrayitem_gc

    def genop_strlen(self, op, arglocs, resloc):
        base_loc = arglocs[0]
        basesize, itemsize, ofs_length = symbolic.get_array_token(rstr.STR,
                                             self.cpu.translate_support_code)
        self.mc.MOV(resloc, addr_add_const(base_loc, ofs_length))

    def genop_unicodelen(self, op, arglocs, resloc):
        base_loc = arglocs[0]
        basesize, itemsize, ofs_length = symbolic.get_array_token(rstr.UNICODE,
                                             self.cpu.translate_support_code)
        self.mc.MOV(resloc, addr_add_const(base_loc, ofs_length))

    def genop_arraylen_gc(self, op, arglocs, resloc):
        base_loc, ofs_loc = arglocs
        assert isinstance(ofs_loc, ImmedLoc)
        self.mc.MOV(resloc, addr_add_const(base_loc, ofs_loc.value))

    def genop_strgetitem(self, op, arglocs, resloc):
        base_loc, ofs_loc = arglocs
        basesize, itemsize, ofs_length = symbolic.get_array_token(rstr.STR,
                                             self.cpu.translate_support_code)
        assert itemsize == 1
        self.mc.MOVZX8(resloc, AddressLoc(base_loc, ofs_loc, 0, basesize))

    def genop_unicodegetitem(self, op, arglocs, resloc):
        base_loc, ofs_loc = arglocs
        basesize, itemsize, ofs_length = symbolic.get_array_token(rstr.UNICODE,
                                             self.cpu.translate_support_code)
        if itemsize == 4:
            self.mc.MOV32(resloc, AddressLoc(base_loc, ofs_loc, 2, basesize))
        elif itemsize == 2:
            self.mc.MOVZX16(resloc, AddressLoc(base_loc, ofs_loc, 1, basesize))
        else:
            assert 0, itemsize

    def genop_read_timestamp(self, op, arglocs, resloc):
        self.mc.RDTSC()
        if longlong.is_64_bit:
            self.mc.SHL_ri(edx.value, 32)
            self.mc.OR_rr(edx.value, eax.value)
        else:
            loc1, = arglocs
            self.mc.MOVD_xr(loc1.value, edx.value)
            self.mc.MOVD_xr(resloc.value, eax.value)
            self.mc.PUNPCKLDQ_xx(resloc.value, loc1.value)

    def genop_guard_guard_true(self, ign_1, guard_op, guard_token, locs, ign_2):
        loc = locs[0]
        self.mc.TEST(loc, loc)
        self.implement_guard(guard_token, 'Z')
    genop_guard_guard_nonnull = genop_guard_guard_true

    def genop_guard_guard_no_exception(self, ign_1, guard_op, guard_token,
                                       locs, ign_2):
        self.mc.CMP(heap(self.cpu.pos_exception()), imm0)
        self.implement_guard(guard_token, 'NZ')

    def genop_guard_guard_not_invalidated(self, ign_1, guard_op, guard_token,
                                     locs, ign_2):
        pos = self.mc.get_relative_pos() + 1 # after potential jmp
        guard_token.pos_jump_offset = pos
        self.pending_guard_tokens.append(guard_token)

    def genop_guard_guard_exception(self, ign_1, guard_op, guard_token,
                                    locs, resloc):
        loc = locs[0]
        loc1 = locs[1]
        self.mc.MOV(loc1, heap(self.cpu.pos_exception()))
        self.mc.CMP(loc1, loc)
        self.implement_guard(guard_token, 'NE')
        self._store_and_reset_exception(self.mc, resloc)

    def _store_and_reset_exception(self, mc, excvalloc=None, exctploc=None,
                                   tmploc=None):
        """ Resest the exception. If excvalloc is None, then store it on the
        frame in jf_guard_exc
        """
        if excvalloc is not None:
            assert excvalloc.is_core_reg()
            mc.MOV(excvalloc, heap(self.cpu.pos_exc_value()))
        elif tmploc is not None: # if both are None, just ignore
            ofs = self.cpu.get_ofs_of_frame_field('jf_guard_exc')
            mc.MOV(tmploc, heap(self.cpu.pos_exc_value()))
            mc.MOV(RawEbpLoc(ofs), tmploc)
        if exctploc is not None:
            assert exctploc.is_core_reg()
            mc.MOV(exctploc, heap(self.cpu.pos_exception()))

        mc.MOV(heap(self.cpu.pos_exception()), imm0)
        mc.MOV(heap(self.cpu.pos_exc_value()), imm0)

    def _restore_exception(self, mc, excvalloc, exctploc, tmploc=None):
        if excvalloc is not None:
            mc.MOV(heap(self.cpu.pos_exc_value()), excvalloc)
        else:
            assert tmploc is not None
            ofs = self.cpu.get_ofs_of_frame_field('jf_guard_exc')
            mc.MOV(tmploc, RawEbpLoc(ofs))
            mc.MOV_bi(ofs, 0)
            mc.MOV(heap(self.cpu.pos_exc_value()), tmploc)
        mc.MOV(heap(self.cpu.pos_exception()), exctploc)

    def _gen_guard_overflow(self, guard_op, guard_token):
        guard_opnum = guard_op.getopnum()
        if guard_opnum == rop.GUARD_NO_OVERFLOW:
            self.implement_guard(guard_token, 'O')
        elif guard_opnum == rop.GUARD_OVERFLOW:
            self.implement_guard(guard_token, 'NO')
        else:
            not_implemented("int_xxx_ovf followed by %s" %
                            guard_op.getopname())

    def genop_guard_int_add_ovf(self, op, guard_op, guard_token, arglocs, result_loc):
        self.mc.ADD(arglocs[0], arglocs[1])
        return self._gen_guard_overflow(guard_op, guard_token)

    def genop_guard_int_sub_ovf(self, op, guard_op, guard_token, arglocs, result_loc):
        self.mc.SUB(arglocs[0], arglocs[1])
        return self._gen_guard_overflow(guard_op, guard_token)

    def genop_guard_int_mul_ovf(self, op, guard_op, guard_token, arglocs, result_loc):
        self.mc.IMUL(arglocs[0], arglocs[1])
        return self._gen_guard_overflow(guard_op, guard_token)

    def genop_guard_guard_false(self, ign_1, guard_op, guard_token, locs, ign_2):
        loc = locs[0]
        self.mc.TEST(loc, loc)
        self.implement_guard(guard_token, 'NZ')
    genop_guard_guard_isnull = genop_guard_guard_false

    def genop_guard_guard_value(self, ign_1, guard_op, guard_token, locs, ign_2):
        if guard_op.getarg(0).type == FLOAT:
            assert guard_op.getarg(1).type == FLOAT
            self.mc.UCOMISD(locs[0], locs[1])
        else:
            self.mc.CMP(locs[0], locs[1])
        self.implement_guard(guard_token, 'NE')

    def _cmp_guard_class(self, locs):
        offset = self.cpu.vtable_offset
        if offset is not None:
            self.mc.CMP(mem(locs[0], offset), locs[1])
        else:
            # XXX hard-coded assumption: to go from an object to its class
            # we use the following algorithm:
            #   - read the typeid from mem(locs[0]), i.e. at offset 0;
            #     this is a complete word (N=4 bytes on 32-bit, N=8 on
            #     64-bits)
            #   - keep the lower half of what is read there (i.e.
            #     truncate to an unsigned 'N / 2' bytes value)
            #   - multiply by 4 (on 32-bits only) and use it as an
            #     offset in type_info_group
            #   - add 16/32 bytes, to go past the TYPE_INFO structure
            loc = locs[1]
            assert isinstance(loc, ImmedLoc)
            classptr = loc.value
            # here, we have to go back from 'classptr' to the value expected
            # from reading the half-word in the object header.  Note that
            # this half-word is at offset 0 on a little-endian machine;
            # it would be at offset 2 or 4 on a big-endian machine.
            from rpython.memory.gctypelayout import GCData
            sizeof_ti = rffi.sizeof(GCData.TYPE_INFO)
            type_info_group = llop.gc_get_type_info_group(llmemory.Address)
            type_info_group = rffi.cast(lltype.Signed, type_info_group)
            expected_typeid = classptr - sizeof_ti - type_info_group
            if IS_X86_32:
                expected_typeid >>= 2
                self.mc.CMP16(mem(locs[0], 0), ImmedLoc(expected_typeid))
            elif IS_X86_64:
                self.mc.CMP32_mi((locs[0].value, 0), expected_typeid)

    def genop_guard_guard_class(self, ign_1, guard_op, guard_token, locs, ign_2):
        self._cmp_guard_class(locs)
        self.implement_guard(guard_token, 'NE')

    def genop_guard_guard_nonnull_class(self, ign_1, guard_op,
                                        guard_token, locs, ign_2):
        self.mc.CMP(locs[0], imm1)
        # Patched below
        self.mc.J_il8(rx86.Conditions['B'], 0)
        jb_location = self.mc.get_relative_pos()
        self._cmp_guard_class(locs)
        # patch the JB above
        offset = self.mc.get_relative_pos() - jb_location
        assert 0 < offset <= 127
        self.mc.overwrite(jb_location-1, chr(offset))
        #
        self.implement_guard(guard_token, 'NE')

    def implement_guard_recovery(self, guard_opnum, faildescr, failargs,
                                 fail_locs, frame_depth):
        exc = (guard_opnum == rop.GUARD_EXCEPTION or
               guard_opnum == rop.GUARD_NO_EXCEPTION or
               guard_opnum == rop.GUARD_NOT_FORCED)
        is_guard_not_invalidated = guard_opnum == rop.GUARD_NOT_INVALIDATED
        is_guard_not_forced = guard_opnum == rop.GUARD_NOT_FORCED
        gcmap = allocate_gcmap(self, frame_depth, JITFRAME_FIXED_SIZE)
        return GuardToken(self.cpu, gcmap, faildescr, failargs,
                          fail_locs, exc, frame_depth,
                          is_guard_not_invalidated, is_guard_not_forced)

    def generate_propagate_error_64(self):
        assert WORD == 8
        startpos = self.mc.get_relative_pos()
        self.mc.JMP(imm(self.propagate_exception_path))
        return startpos

    def generate_quick_failure(self, guardtok):
        """ Gather information about failure
        """
        startpos = self.mc.get_relative_pos()
        fail_descr, target = self.store_info_on_descr(startpos, guardtok)
        self.mc.PUSH(imm(fail_descr))
        self.push_gcmap(self.mc, guardtok.gcmap, push=True)
        self.mc.JMP(imm(target))
        return startpos

    def push_gcmap(self, mc, gcmap, push=False, mov=False, store=False):
        if push:
            mc.PUSH(imm(rffi.cast(lltype.Signed, gcmap)))
        elif mov:
            mc.MOV(RawEspLoc(0, REF),
                   imm(rffi.cast(lltype.Signed, gcmap)))
        else:
            assert store
            ofs = self.cpu.get_ofs_of_frame_field('jf_gcmap')
            mc.MOV(raw_stack(ofs), imm(rffi.cast(lltype.Signed, gcmap)))

    def pop_gcmap(self, mc):
        ofs = self.cpu.get_ofs_of_frame_field('jf_gcmap')
        mc.MOV_bi(ofs, 0)

    def new_stack_loc(self, i, pos, tp):
        base_ofs = self.cpu.get_baseofs_of_frame_field()
        return FrameLoc(i, get_ebp_ofs(base_ofs, i), tp)

    def setup_failure_recovery(self):
        self.failure_recovery_code = [0, 0, 0, 0]

    def _push_all_regs_to_frame(self, mc, ignored_regs, withfloats,
                                callee_only=False):
        # Push all general purpose registers
        base_ofs = self.cpu.get_baseofs_of_frame_field()
        if callee_only:
            regs = gpr_reg_mgr_cls.save_around_call_regs
        else:
            regs = gpr_reg_mgr_cls.all_regs
        for i, gpr in enumerate(regs):
            if gpr not in ignored_regs:
                mc.MOV_br(i * WORD + base_ofs, gpr.value)
        if withfloats:
            if IS_X86_64:
                coeff = 1
            else:
                coeff = 2
            # Push all XMM regs
            ofs = len(gpr_reg_mgr_cls.all_regs)
            for i in range(len(xmm_reg_mgr_cls.all_regs)):
                mc.MOVSD_bx((ofs + i * coeff) * WORD + base_ofs, i)

    def _pop_all_regs_from_frame(self, mc, ignored_regs, withfloats,
                                 callee_only=False):
        # Pop all general purpose registers
        base_ofs = self.cpu.get_baseofs_of_frame_field()
        if callee_only:
            regs = gpr_reg_mgr_cls.save_around_call_regs
        else:
            regs = gpr_reg_mgr_cls.all_regs
        for i, gpr in enumerate(regs):
            if gpr not in ignored_regs:
                mc.MOV_rb(gpr.value, i * WORD + base_ofs)
        if withfloats:
            # Pop all XMM regs
            if IS_X86_64:
                coeff = 1
            else:
                coeff = 2
            ofs = len(gpr_reg_mgr_cls.all_regs)
            for i in range(len(xmm_reg_mgr_cls.all_regs)):
                mc.MOVSD_xb(i, (ofs + i * coeff) * WORD + base_ofs)

    def _build_failure_recovery(self, exc, withfloats=False):
        mc = codebuf.MachineCodeBlockWrapper()
        self.mc = mc

        self._push_all_regs_to_frame(mc, [], withfloats)

        if exc:
            # We might have an exception pending.  Load it into ebx...
            mc.MOV(ebx, heap(self.cpu.pos_exc_value()))
            mc.MOV(heap(self.cpu.pos_exception()), imm0)
            mc.MOV(heap(self.cpu.pos_exc_value()), imm0)
            # ...and save ebx into 'jf_guard_exc'
            offset = self.cpu.get_ofs_of_frame_field('jf_guard_exc')
            mc.MOV_br(offset, ebx.value)

        # now we return from the complete frame, which starts from
        # _call_header_with_stack_check().  The LEA in _call_footer below
        # throws away most of the frame, including all the PUSHes that we
        # did just above.
        ofs = self.cpu.get_ofs_of_frame_field('jf_descr')
        ofs2 = self.cpu.get_ofs_of_frame_field('jf_gcmap')
        mc.POP(eax)
        mc.MOV_br(ofs2, eax.value)
        mc.POP(eax)
        mc.MOV_br(ofs, eax.value)
        # the return value is the jitframe
        mc.MOV_rr(eax.value, ebp.value)

        self._call_footer()
        rawstart = mc.materialize(self.cpu.asmmemmgr, [])
        self.failure_recovery_code[exc + 2 * withfloats] = rawstart
        self.mc = None

    def genop_finish(self, op, arglocs, result_loc):
        base_ofs = self.cpu.get_baseofs_of_frame_field()
        if len(arglocs) == 2:
            [return_val, fail_descr_loc] = arglocs
            if op.getarg(0).type == FLOAT and not IS_X86_64:
                size = WORD * 2
            else:
                size = WORD
            self.save_into_mem(raw_stack(base_ofs), return_val, imm(size))
        else:
            [fail_descr_loc] = arglocs
        ofs = self.cpu.get_ofs_of_frame_field('jf_descr')
        self.mov(fail_descr_loc, RawEbpLoc(ofs))
        arglist = op.getarglist()
        if arglist and arglist[0].type == REF:
            gcmap = self.gcmap_for_finish
            self.push_gcmap(self.mc, gcmap, store=True)
        else:
            # note that the 0 here is redundant, but I would rather
            # keep that one and kill all the others
            ofs = self.cpu.get_ofs_of_frame_field('jf_gcmap')
            self.mc.MOV_bi(ofs, 0)
        self.mc.MOV_rr(eax.value, ebp.value)
        # exit function
        self._call_footer()

    def implement_guard(self, guard_token, condition=None):
        # These jumps are patched later.
        if condition:
            self.mc.J_il(rx86.Conditions[condition], 0)
        else:
            self.mc.JMP_l(0)
        guard_token.pos_jump_offset = self.mc.get_relative_pos() - 4
        self.pending_guard_tokens.append(guard_token)

    def genop_call(self, op, arglocs, resloc):
        self._genop_call(op, arglocs, resloc)

    def _genop_call(self, op, arglocs, resloc, is_call_release_gil=False):
        from rpython.jit.backend.llsupport.descr import CallDescr

        cb = callbuilder.CallBuilder(self, arglocs[2], arglocs[3:], resloc)

        descr = op.getdescr()
        assert isinstance(descr, CallDescr)
        cb.callconv = descr.get_call_conv()
        cb.argtypes = descr.get_arg_types()
        cb.restype  = descr.get_result_type()
        sizeloc = arglocs[0]
        assert isinstance(sizeloc, ImmedLoc)
        cb.ressize = sizeloc.value
        signloc = arglocs[1]
        assert isinstance(signloc, ImmedLoc)
        cb.ressign = signloc.value

        if is_call_release_gil:
            cb.emit_call_release_gil()
        else:
            cb.emit()

    def _store_force_index(self, guard_op):
        faildescr = guard_op.getdescr()
        ofs = self.cpu.get_ofs_of_frame_field('jf_force_descr')
        self.mc.MOV(raw_stack(ofs), imm(rffi.cast(lltype.Signed,
                                 cast_instance_to_gcref(faildescr))))

    def _emit_guard_not_forced(self, guard_token):
        ofs = self.cpu.get_ofs_of_frame_field('jf_descr')
        self.mc.CMP_bi(ofs, 0)
        self.implement_guard(guard_token, 'NE')

    def genop_guard_call_may_force(self, op, guard_op, guard_token,
                                   arglocs, result_loc):
        self._store_force_index(guard_op)
        self._genop_call(op, arglocs, result_loc)
        self._emit_guard_not_forced(guard_token)

    def genop_guard_call_release_gil(self, op, guard_op, guard_token,
                                     arglocs, result_loc):
        self._store_force_index(guard_op)
        self._genop_call(op, arglocs, result_loc, is_call_release_gil=True)
        self._emit_guard_not_forced(guard_token)

    def call_reacquire_gil(self, gcrootmap, save_loc):
        # save the previous result (eax/xmm0) into the stack temporarily.
        # XXX like with call_release_gil(), we assume that we don't need
        # to save xmm0 in this case.
        if isinstance(save_loc, RegLoc) and not save_loc.is_xmm:
            self.mc.MOV_sr(WORD, save_loc.value)
        # call the reopenstack() function (also reacquiring the GIL)
        if gcrootmap.is_shadow_stack:
            args = []
            css = 0
        else:
            from rpython.memory.gctransform import asmgcroot
            css = WORD * (PASS_ON_MY_FRAME - asmgcroot.JIT_USE_WORDS)
            if IS_X86_32:
                reg = eax
            elif IS_X86_64:
                reg = edi
            self.mc.LEA_rs(reg.value, css)
            args = [reg]
        self._emit_call(imm(self.reacqgil_addr), args, can_collect=False)
        #
        # Now that we required the GIL, we can reload a possibly modified ebp
        if not gcrootmap.is_shadow_stack:
            # special-case: reload ebp from the css
            from rpython.memory.gctransform import asmgcroot
            index_of_ebp = css + WORD * (2+asmgcroot.INDEX_OF_EBP)
            self.mc.MOV_rs(ebp.value, index_of_ebp)  # MOV EBP, [css.ebp]
        #else:
        #   for shadowstack, done for us by _reload_frame_if_necessary()
        self._reload_frame_if_necessary(self.mc)
        self.set_extra_stack_depth(self.mc, 0)
        #
        # restore the result from the stack
        if isinstance(save_loc, RegLoc) and not save_loc.is_xmm:
            self.mc.MOV_rs(save_loc.value, WORD)

    def imm(self, v):
        return imm(v)

    # ------------------- CALL ASSEMBLER --------------------------

    def genop_guard_call_assembler(self, op, guard_op, guard_token,
                                   arglocs, result_loc):
        if len(arglocs) == 2:
            [argloc, vloc] = arglocs
        else:
            [argloc] = arglocs
            vloc = self.imm(0)
        self.call_assembler(op, guard_op, argloc, vloc, result_loc, eax)
        self._emit_guard_not_forced(guard_token)

    def _call_assembler_emit_call(self, addr, argloc, _):
        self.simple_call(addr, [argloc])

    def _call_assembler_emit_helper_call(self, addr, arglocs, result_loc):
        self.simple_call(addr, arglocs, result_loc)

    def _call_assembler_check_descr(self, value, tmploc):
        ofs = self.cpu.get_ofs_of_frame_field('jf_descr')
        self.mc.CMP(mem(eax, ofs), imm(value))
        # patched later
        self.mc.J_il8(rx86.Conditions['E'], 0) # goto B if we get 'done_with_this_frame'
        return self.mc.get_relative_pos()

    def _call_assembler_patch_je(self, result_loc, je_location):
        if (IS_X86_32 and isinstance(result_loc, FrameLoc) and
            result_loc.type == FLOAT):
            self.mc.FSTPL_b(result_loc.value)
        self.mc.JMP_l8(0) # jump to done, patched later
        jmp_location = self.mc.get_relative_pos()
        #
        offset = jmp_location - je_location
        assert 0 < offset <= 127
        self.mc.overwrite(je_location - 1, chr(offset))
        #
        return jmp_location

    def _call_assembler_reset_vtoken(self, jd, vloc):
        from rpython.jit.backend.llsupport.descr import FieldDescr
        fielddescr = jd.vable_token_descr
        assert isinstance(fielddescr, FieldDescr)
        vtoken_ofs = fielddescr.offset
        self.mc.MOV(edx, vloc) # we know vloc is on the current frame
        self.mc.MOV_mi((edx.value, vtoken_ofs), 0)
        # in the line above, TOKEN_NONE = 0

    def _call_assembler_load_result(self, op, result_loc):
        if op.result is not None:
            # load the return value from the dead frame's value index 0
            kind = op.result.type
            descr = self.cpu.getarraydescr_for_frame(kind)
            ofs = self.cpu.unpack_arraydescr(descr)
            if kind == FLOAT:
                self.mc.MOVSD_xm(xmm0.value, (eax.value, ofs))
                if result_loc is not xmm0:
                    self.mc.MOVSD(result_loc, xmm0)
            else:
                assert result_loc is eax
                self.mc.MOV_rm(eax.value, (eax.value, ofs))

    def _call_assembler_patch_jmp(self, jmp_location):
        offset = self.mc.get_relative_pos() - jmp_location
        assert 0 <= offset <= 127
        self.mc.overwrite(jmp_location - 1, chr(offset))

    # ------------------- END CALL ASSEMBLER -----------------------

    def _write_barrier_fastpath(self, mc, descr, arglocs, array=False,
                                is_frame=False, align_stack=False):
        # Write code equivalent to write_barrier() in the GC: it checks
        # a flag in the object at arglocs[0], and if set, it calls a
        # helper piece of assembler.  The latter saves registers as needed
        # and call the function jit_remember_young_pointer() from the GC.
        if we_are_translated():
            cls = self.cpu.gc_ll_descr.has_write_barrier_class()
            assert cls is not None and isinstance(descr, cls)
        #
        card_marking = False
        mask = descr.jit_wb_if_flag_singlebyte
        if array and descr.jit_wb_cards_set != 0:
            # assumptions the rest of the function depends on:
            assert (descr.jit_wb_cards_set_byteofs ==
                    descr.jit_wb_if_flag_byteofs)
            assert descr.jit_wb_cards_set_singlebyte == -0x80
            card_marking = True
            mask = descr.jit_wb_if_flag_singlebyte | -0x80
        #
        loc_base = arglocs[0]
        if is_frame:
            assert loc_base is ebp
            loc = raw_stack(descr.jit_wb_if_flag_byteofs)
        else:
            loc = addr_add_const(loc_base, descr.jit_wb_if_flag_byteofs)
        mc.TEST8(loc, imm(mask))
        mc.J_il8(rx86.Conditions['Z'], 0) # patched later
        jz_location = mc.get_relative_pos()

        # for cond_call_gc_wb_array, also add another fast path:
        # if GCFLAG_CARDS_SET, then we can just set one bit and be done
        if card_marking:
            # GCFLAG_CARDS_SET is in this byte at 0x80, so this fact can
            # been checked by the status flags of the previous TEST8
            mc.J_il8(rx86.Conditions['S'], 0) # patched later
            js_location = mc.get_relative_pos()
        else:
            js_location = 0

        # Write only a CALL to the helper prepared in advance, passing it as
        # argument the address of the structure we are writing into
        # (the first argument to COND_CALL_GC_WB).
        helper_num = card_marking
        if is_frame:
            helper_num = 4
        elif self._regalloc is not None and self._regalloc.xrm.reg_bindings:
            helper_num += 2
        if self.wb_slowpath[helper_num] == 0:    # tests only
            assert not we_are_translated()
            self.cpu.gc_ll_descr.write_barrier_descr = descr
            self._build_wb_slowpath(card_marking,
                                    bool(self._regalloc.xrm.reg_bindings))
            assert self.wb_slowpath[helper_num] != 0
        #
        if not is_frame:
            mc.PUSH(loc_base)
        if is_frame and align_stack:
            mc.SUB_ri(esp.value, 16 - WORD) # erase the return address
        mc.CALL(imm(self.wb_slowpath[helper_num]))
        if is_frame and align_stack:
            mc.ADD_ri(esp.value, 16 - WORD) # erase the return address

        if card_marking:
            # The helper ends again with a check of the flag in the object.
            # So here, we can simply write again a 'JNS', which will be
            # taken if GCFLAG_CARDS_SET is still not set.
            mc.J_il8(rx86.Conditions['NS'], 0) # patched later
            jns_location = mc.get_relative_pos()
            #
            # patch the JS above
            offset = mc.get_relative_pos() - js_location
            assert 0 < offset <= 127
            mc.overwrite(js_location-1, chr(offset))
            #
            # case GCFLAG_CARDS_SET: emit a few instructions to do
            # directly the card flag setting
            loc_index = arglocs[1]
            if isinstance(loc_index, RegLoc):
                if IS_X86_64 and isinstance(loc_base, RegLoc):
                    # copy loc_index into r11
                    tmp1 = X86_64_SCRATCH_REG
                    mc.MOV_rr(tmp1.value, loc_index.value)
                    final_pop = False
                else:
                    # must save the register loc_index before it is mutated
                    mc.PUSH_r(loc_index.value)
                    tmp1 = loc_index
                    final_pop = True
                # SHR tmp, card_page_shift
                mc.SHR_ri(tmp1.value, descr.jit_wb_card_page_shift)
                # XOR tmp, -8
                mc.XOR_ri(tmp1.value, -8)
                # BTS [loc_base], tmp
                mc.BTS(addr_add_const(loc_base, 0), tmp1)
                # done
                if final_pop:
                    mc.POP_r(loc_index.value)
                #
            elif isinstance(loc_index, ImmedLoc):
                byte_index = loc_index.value >> descr.jit_wb_card_page_shift
                byte_ofs = ~(byte_index >> 3)
                byte_val = 1 << (byte_index & 7)
                mc.OR8(addr_add_const(loc_base, byte_ofs), imm(byte_val))
            else:
                raise AssertionError("index is neither RegLoc nor ImmedLoc")
            #
            # patch the JNS above
            offset = mc.get_relative_pos() - jns_location
            assert 0 < offset <= 127
            mc.overwrite(jns_location-1, chr(offset))

        # patch the JZ above
        offset = mc.get_relative_pos() - jz_location
        assert 0 < offset <= 127
        mc.overwrite(jz_location-1, chr(offset))

    def genop_discard_cond_call_gc_wb(self, op, arglocs):
        self._write_barrier_fastpath(self.mc, op.getdescr(), arglocs)

    def genop_discard_cond_call_gc_wb_array(self, op, arglocs):
        self._write_barrier_fastpath(self.mc, op.getdescr(), arglocs,
                                     array=True)

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

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

    def not_implemented_op_guard(self, op, guard_op,
                                 failaddr, arglocs, resloc):
        not_implemented("not implemented operation (guard): %s" %
                        op.getopname())

    def closing_jump(self, target_token):
        target = target_token._ll_loop_code
        if target_token in self.target_tokens_currently_compiling:
            curpos = self.mc.get_relative_pos() + 5
            self.mc.JMP_l(target - curpos)
        else:
            self.mc.JMP(imm(target))

    def label(self):
        self._check_frame_depth_debug(self.mc)

    def malloc_cond(self, nursery_free_adr, nursery_top_adr, size, gcmap):
        assert size & (WORD-1) == 0     # must be correctly aligned
        self.mc.MOV(eax, heap(nursery_free_adr))
        self.mc.LEA_rm(edi.value, (eax.value, size))
        self.mc.CMP(edi, heap(nursery_top_adr))
        self.mc.J_il8(rx86.Conditions['NA'], 0) # patched later
        jmp_adr = self.mc.get_relative_pos()
        # save the gcmap
        self.push_gcmap(self.mc, gcmap, mov=True)
        self.mc.CALL(imm(self.malloc_slowpath))
        offset = self.mc.get_relative_pos() - jmp_adr
        assert 0 < offset <= 127
        self.mc.overwrite(jmp_adr-1, chr(offset))
        self.mc.MOV(heap(nursery_free_adr), edi)

    def malloc_cond_varsize_frame(self, nursery_free_adr, nursery_top_adr,
                                  sizeloc, gcmap):
        if sizeloc is eax:
            self.mc.MOV(edi, sizeloc)
            sizeloc = edi
        self.mc.MOV(eax, heap(nursery_free_adr))
        if sizeloc is edi:
            self.mc.ADD_rr(edi.value, eax.value)
        else:
            self.mc.LEA_ra(edi.value, (eax.value, sizeloc.value, 0, 0))
        self.mc.CMP(edi, heap(nursery_top_adr))
        self.mc.J_il8(rx86.Conditions['NA'], 0) # patched later
        jmp_adr = self.mc.get_relative_pos()
        # save the gcmap
        self.push_gcmap(self.mc, gcmap, mov=True)
        self.mc.CALL(imm(self.malloc_slowpath))
        offset = self.mc.get_relative_pos() - jmp_adr
        assert 0 < offset <= 127
        self.mc.overwrite(jmp_adr-1, chr(offset))
        self.mc.MOV(heap(nursery_free_adr), edi)

    def malloc_cond_varsize(self, kind, nursery_free_adr, nursery_top_adr,
                            lengthloc, itemsize, maxlength, gcmap,
                            arraydescr):
        from rpython.jit.backend.llsupport.descr import ArrayDescr
        assert isinstance(arraydescr, ArrayDescr)

        # lengthloc is the length of the array, which we must not modify!
        assert lengthloc is not eax and lengthloc is not edi
        if isinstance(lengthloc, RegLoc):
            varsizeloc = lengthloc
        else:
            self.mc.MOV(edi, lengthloc)
            varsizeloc = edi

        self.mc.CMP(varsizeloc, imm(maxlength))
        self.mc.J_il8(rx86.Conditions['A'], 0) # patched later
        jmp_adr0 = self.mc.get_relative_pos()

        self.mc.MOV(eax, heap(nursery_free_adr))
        if valid_addressing_size(itemsize):
            shift = get_scale(itemsize)
        else:
            shift = self._imul_const_scaled(self.mc, edi.value,
                                            varsizeloc.value, itemsize)
            varsizeloc = edi
        # now varsizeloc is a register != eax.  The size of
        # the variable part of the array is (varsizeloc << shift)
        assert arraydescr.basesize >= self.gc_minimal_size_in_nursery
        constsize = arraydescr.basesize + self.gc_size_of_header
        force_realignment = (itemsize % WORD) != 0
        if force_realignment:
            constsize += WORD - 1
        self.mc.LEA_ra(edi.value, (eax.value, varsizeloc.value, shift,
                                   constsize))
        if force_realignment:
            self.mc.AND_ri(edi.value, ~(WORD - 1))
        # now edi contains the total size in bytes, rounded up to a multiple
        # of WORD, plus nursery_free_adr
        self.mc.CMP(edi, heap(nursery_top_adr))
        self.mc.J_il8(rx86.Conditions['NA'], 0) # patched later
        jmp_adr1 = self.mc.get_relative_pos()
        #
        offset = self.mc.get_relative_pos() - jmp_adr0
        assert 0 < offset <= 127
        self.mc.overwrite(jmp_adr0-1, chr(offset))
        # save the gcmap
        self.push_gcmap(self.mc, gcmap, mov=True)   # mov into RawEspLoc(0)
        if kind == rewrite.FLAG_ARRAY:
            self.mc.MOV_si(WORD, itemsize)
            self.mc.MOV(edi, lengthloc)
            self.mc.MOV_ri(eax.value, arraydescr.tid)
            addr = self.malloc_slowpath_varsize
        else:
            if kind == rewrite.FLAG_STR:
                addr = self.malloc_slowpath_str
            else:
                assert kind == rewrite.FLAG_UNICODE
                addr = self.malloc_slowpath_unicode
            self.mc.MOV(edi, lengthloc)
        self.mc.CALL(imm(addr))
        self.mc.JMP_l8(0)      # jump to done, patched later
        jmp_location = self.mc.get_relative_pos()
        #
        offset = self.mc.get_relative_pos() - jmp_adr1
        assert 0 < offset <= 127
        self.mc.overwrite(jmp_adr1-1, chr(offset))
        # write down the tid, but not if it's the result of the CALL
        self.mc.MOV(mem(eax, 0), imm(arraydescr.tid))
        # while we're at it, this line is not needed if we've done the CALL
        self.mc.MOV(heap(nursery_free_adr), edi)
        #
        offset = self.mc.get_relative_pos() - jmp_location
        assert 0 < offset <= 127
        self.mc.overwrite(jmp_location - 1, chr(offset))

    def force_token(self, reg):
        # XXX kill me
        assert isinstance(reg, RegLoc)
        self.mc.MOV_rr(reg.value, ebp.value)

genop_discard_list = [Assembler386.not_implemented_op_discard] * rop._LAST
genop_list = [Assembler386.not_implemented_op] * rop._LAST
genop_llong_list = {}
genop_math_list = {}
genop_guard_list = [Assembler386.not_implemented_op_guard] * rop._LAST

for name, value in Assembler386.__dict__.iteritems():
    if name.startswith('genop_discard_'):
        opname = name[len('genop_discard_'):]
        num = getattr(rop, opname.upper())
        genop_discard_list[num] = value
    elif name.startswith('genop_guard_') and name != 'genop_guard_exception':
        opname = name[len('genop_guard_'):]
        num = getattr(rop, opname.upper())
        genop_guard_list[num] = value
    elif name.startswith('genop_llong_'):
        opname = name[len('genop_llong_'):]
        num = getattr(EffectInfo, 'OS_LLONG_' + opname.upper())
        genop_llong_list[num] = value
    elif name.startswith('genop_math_'):
        opname = name[len('genop_math_'):]
        num = getattr(EffectInfo, 'OS_MATH_' + opname.upper())
        genop_math_list[num] = value
    elif name.startswith('genop_'):
        opname = name[len('genop_'):]
        num = getattr(rop, opname.upper())
        genop_list[num] = value

# XXX: ri386 migration shims:
def addr_add(reg_or_imm1, reg_or_imm2, offset=0, scale=0):
    return AddressLoc(reg_or_imm1, reg_or_imm2, scale, offset)

def addr_add_const(reg_or_imm1, offset):
    return AddressLoc(reg_or_imm1, imm0, 0, offset)

def mem(loc, offset):
    return AddressLoc(loc, imm0, 0, offset)

def raw_stack(offset, type=INT):
    return RawEbpLoc(offset, type)

def heap(addr):
    return AddressLoc(ImmedLoc(addr), imm0, 0, 0)

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

class BridgeAlreadyCompiled(Exception):
    pass
