def get_typeid_from_classptr_if_gcremovetypeptr(self, classptr):
"""Returns the typeid corresponding from a vtable pointer 'classptr'.
This function only works if cpu.vtable_offset is None, i.e. in
a translation with --gcremovetypeptr.
"""
from rpython.memory.gctypelayout import GCData
assert self.gcdescr.config.translation.gcremovetypeptr
# hard-coded assumption: to go from an object to its class
# we would 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
# here, we have to go back from 'classptr' back to the typeid,
# so we do (part of) these computations in reverse.
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 WORD == 4:
expected_typeid >>= 2
return expected_typeid
def get_typeid_from_classptr_if_gcremovetypeptr(self, classptr):
"""Returns the typeid corresponding from a vtable pointer 'classptr'.
This function only works if cpu.vtable_offset is None, i.e. in
a translation with --gcremovetypeptr.
"""
from rpython.memory.gctypelayout import GCData
assert self.gcdescr.config.translation.gcremovetypeptr
# hard-coded assumption: to go from an object to its class
# we would 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
# here, we have to go back from 'classptr' back to the typeid,
# so we do (part of) these computations in reverse.
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 WORD == 4:
expected_typeid >>= 2
return expected_typeid
def get_translated_info_for_typeinfo(self):
from rpython.memory.gctypelayout import GCData
type_info_group = llop.gc_get_type_info_group(llmemory.Address)
type_info_group = rffi.cast(lltype.Signed, type_info_group)
if WORD == 4:
shift_by = 2
elif WORD == 8:
shift_by = 0
sizeof_ti = rffi.sizeof(GCData.TYPE_INFO)
return (type_info_group, shift_by, sizeof_ti)
def get_translated_info_for_typeinfo(self):
from rpython.memory.gctypelayout import GCData
type_info_group = llop.gc_get_type_info_group(llmemory.Address)
type_info_group = rffi.cast(lltype.Signed, type_info_group)
if WORD == 4:
shift_by = 2
elif WORD == 8:
shift_by = 0
sizeof_ti = rffi.sizeof(GCData.TYPE_INFO)
return (type_info_group, shift_by, sizeof_ti)
def ClassPtrTypeID(classptr):
"""ASMJSValue representing the typeid for a class pointer.
This is a special value for handling class comparisons when we're not
using type pointers. It extracts an "expected type id" from the class
pointer, which can be compared agaist the first half-word in the object
pointer. Logic shamelessly cargo-culted from x86 backend.
"""
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)
typeid = Minus(classptr, ConstInt(sizeof_ti + type_info_group))
typeid = RShift(typeid, ConstInt(2))
typeid = And(typeid, ConstInt(0xFFFF))
return typeid
def ClassPtrTypeID(classptr):
"""ASMJSValue representing the typeid for a class pointer.
This is a special value for handling class comparisons when we're not
using type pointers. It extracts an "expected type id" from the class
pointer, which can be compared agaist the first half-word in the object
pointer. Logic shamelessly cargo-culted from x86 backend.
"""
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)
typeid = Minus(classptr, ConstInt(sizeof_ti + type_info_group))
typeid = RShift(typeid, ConstInt(2))
typeid = And(typeid, ConstInt(0xFFFF))
return typeid
