void ScanAddress::ScanAddressesInRegion(PolyWord *region, PolyWord *end)
{
PolyWord *pt = region;
while (pt < end)
{
pt++; // Skip length word.
// pt actually points AT the object here.
PolyObject *obj = (PolyObject*)pt;
if (obj->ContainsForwardingPtr()) /* skip over moved object */
{
// We can now get multiple forwarding pointers as a result
// of applying ShareData repeatedly. Perhaps we should
// turn the forwarding pointers back into normal words in
// an extra pass.
while (obj->ContainsForwardingPtr())
obj = obj->GetForwardingPtr();
ASSERT(obj->ContainsNormalLengthWord());
CheckObject(obj);
pt += obj->Length();
}
else
{
ASSERT(obj->ContainsNormalLengthWord());
POLYUNSIGNED length = obj->Length();
if (pt+length > end)
Crash("Malformed object at %p - length %lu\n", pt, length);
if (length != 0)
ScanAddressesInObject(obj);
pt += length;
}
}
}
// Returns the new address if the argument is the address of an object that
// has moved, otherwise returns the original.
PolyWord SaveFixupAddress::GetNewAddress(PolyWord old)
{
if (old.IsTagged() || old == PolyWord::FromUnsigned(0) || gMem.IsIOPointer(old.AsAddress()))
return old; // Nothing to do.
// When we are updating addresses in the stack or in code segments we may have
// code pointers.
if (old.IsCodePtr())
{
// Find the start of the code segment
PolyObject *oldObject = ObjCodePtrToPtr(old.AsCodePtr());
// Calculate the byte offset of this value within the code object.
POLYUNSIGNED offset = old.AsCodePtr() - (byte*)oldObject;
PolyWord newObject = GetNewAddress(oldObject);
return PolyWord::FromCodePtr(newObject.AsCodePtr() + offset);
}
ASSERT(old.IsDataPtr());
PolyObject *obj = old.AsObjPtr();
if (obj->ContainsForwardingPtr()) // tombstone is a pointer to a moved object
{
PolyObject *newp = obj->GetForwardingPtr();
ASSERT (newp->ContainsNormalLengthWord());
return newp;
}
ASSERT (obj->ContainsNormalLengthWord()); // object is not moved
return old;
}
bool GetSharing::TestForScan(PolyWord *pt)
{
PolyObject *obj;
// This may be a forwarding pointer left over from a minor GC that did
// not complete or it may be a sharing chain pointer that we've set up.
while (1)
{
PolyWord p = *pt;
ASSERT(p.IsDataPtr());
obj = p.AsObjPtr();
PolyWord *lengthWord = ((PolyWord*)obj) - 1;
LocalMemSpace *space = gMem.LocalSpaceForAddress(lengthWord);
if (space == 0)
return false; // Ignore it if it points to a permanent area
if (space->bitmap.TestBit(space->wordNo(lengthWord)))
return false;
// Wasn't marked - must be a forwarding pointer.
if (obj->ContainsForwardingPtr())
{
obj = obj->GetForwardingPtr();
*pt = obj;
}
else break;
}
ASSERT(obj->ContainsNormalLengthWord());
totalVisited += 1;
totalSize += obj->Length() + 1;
return true;
}
static void CheckAddress(PolyWord *pt)
{
MemSpace *space = gMem.SpaceForAddress(pt-1);
if (space == 0)
{
Log("Check: Bad pointer %p (no space found)\n", pt);
ASSERT(space != 0);
}
if (space->spaceType == ST_STACK) // This may not have valid length words.
return;
PolyObject *obj = (PolyObject*)pt;
ASSERT(obj->ContainsNormalLengthWord());
POLYUNSIGNED length = obj->Length();
if (pt+length > space->top)
{
Log("Check: Bad pointer %p (space %p) length %" POLYUFMT "\n", pt, space, length);
ASSERT(pt+length <= space->top);
}
if (space->spaceType == ST_LOCAL)
{
LocalMemSpace *lSpace = (LocalMemSpace*)space;
if (!((pt > lSpace->bottom && pt+length <= lSpace->lowerAllocPtr) ||
(pt > lSpace->upperAllocPtr && pt+length <= space->top)))
{
Log("Check: Bad pointer %p (space %p) length %" POLYUFMT " outside allocated area\n", pt, space, length);
ASSERT((pt > lSpace->bottom && pt+length <= lSpace->lowerAllocPtr) ||
(pt > lSpace->upperAllocPtr && pt+length <= space->top));
}
}
}
static void SetBitmaps(LocalMemSpace *space, PolyWord *pt, PolyWord *top)
{
while (pt < top)
{
PolyObject *obj = (PolyObject*)++pt;
// If it has been copied by a minor collection skip it
if (obj->ContainsForwardingPtr())
{
obj = FollowForwarding(obj);
ASSERT(obj->ContainsNormalLengthWord());
pt += obj->Length();
}
else
{
POLYUNSIGNED L = obj->LengthWord();
POLYUNSIGNED n = OBJ_OBJECT_LENGTH(L);
if (L & _OBJ_GC_MARK)
{
obj->SetLengthWord(L & ~(_OBJ_GC_MARK));
POLYUNSIGNED bitno = space->wordNo(pt);
space->bitmap.SetBits(bitno - 1, n + 1);
if (OBJ_IS_MUTABLE_OBJECT(L))
space->m_marked += n + 1;
else
space->i_marked += n + 1;
if ((PolyWord*)obj <= space->fullGCLowerLimit)
space->fullGCLowerLimit = (PolyWord*)obj-1;
if (OBJ_IS_WEAKREF_OBJECT(L))
{
// Add this to the limits for the containing area.
PolyWord *baseAddr = (PolyWord*)obj;
PolyWord *startAddr = baseAddr-1; // Must point AT length word.
PolyWord *endObject = baseAddr + n;
if (startAddr < space->lowestWeak) space->lowestWeak = startAddr;
if (endObject > space->highestWeak) space->highestWeak = endObject;
}
}
pt += n;
}
}
}
// Returns the new address if the argument is the address of an object that
// has moved, otherwise returns the original.
PolyWord ProcessFixupAddress::GetNewAddress(PolyWord old)
{
if (old.IsTagged() || old == PolyWord::FromUnsigned(0) || gMem.IsIOPointer(old.AsAddress()))
return old; // Nothing to do.
// When we are updating addresses in the stack or in code segments we may have
// code pointers.
if (old.IsCodePtr())
{
// Find the start of the code segment
PolyObject *oldObject = ObjCodePtrToPtr(old.AsCodePtr());
// Calculate the byte offset of this value within the code object.
POLYUNSIGNED offset = old.AsCodePtr() - (byte*)oldObject;
PolyWord newObject = GetNewAddress(oldObject);
return PolyWord::FromCodePtr(newObject.AsCodePtr() + offset);
}
ASSERT(old.IsDataPtr());
PolyObject *obj = old.AsObjPtr();
POLYUNSIGNED L = obj->LengthWord();
// Generally each address will point to an object processed at a lower depth.
// The exception is if we have a cycle and have assigned the rest of the
// structure to a higher depth.
// N.B. We return the original address here but this could actually share
// with something else and not be retained.
if (OBJ_IS_DEPTH(L))
return old;
if (obj->ContainsForwardingPtr()) // tombstone is a pointer to a shared object
{
PolyObject *newp = obj->GetForwardingPtr();
// ASSERT (newp->ContainsNormalLengthWord());
return newp;
}
ASSERT (obj->ContainsNormalLengthWord()); // object is not shared
return old;
}
