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/* Copyright (C) 2012 Matthew Fluet.
* Copyright (C) 1999-2008 Henry Cejtin, Matthew Fluet, Suresh
* Jagannathan, and Stephen Weeks.
* Copyright (C) 1997-2000 NEC Research Institute.
*
* MLton is released under a BSD-style license.
* See the file MLton-LICENSE for details.
*/
#if ASSERT
bool isPointerInToSpace (GC_state s, pointer p) {
return (not (isPointer (p))
or (s->forwardState.toStart <= p and p < s->forwardState.toLimit));
}
bool isObjptrInToSpace (GC_state s, objptr op) {
pointer p;
if (not (isObjptr (op)))
return TRUE;
p = objptrToPointer (op, s->forwardState.toStart);
return isPointerInToSpace (s, p);
}
#endif
/* forward (s, opp)
* Forwards the object pointed to by *opp and updates *opp to point to
* the new object.
*/
void forwardObjptr (GC_state s, objptr *opp) {
objptr op;
pointer p;
GC_header header;
op = *opp;
p = objptrToPointer (op, s->heap.start);
if (DEBUG_DETAILED)
fprintf (stderr,
"forwardObjptr opp = "FMTPTR" op = "FMTOBJPTR" p = "FMTPTR"\n",
(uintptr_t)opp, op, (uintptr_t)p);
assert (isObjptrInFromSpace (s, *opp));
header = getHeader (p);
if (DEBUG_DETAILED and header == GC_FORWARDED)
fprintf (stderr, " already FORWARDED\n");
if (header != GC_FORWARDED) { /* forward the object */
size_t size, skip;
size_t headerBytes, objectBytes;
GC_objectTypeTag tag;
uint16_t bytesNonObjptrs, numObjptrs;
splitHeader(s, header, &tag, NULL, &bytesNonObjptrs, &numObjptrs);
/* Compute the space taken by the header and object body. */
if ((NORMAL_TAG == tag) or (WEAK_TAG == tag)) { /* Fixed size object. */
headerBytes = GC_NORMAL_HEADER_SIZE;
objectBytes = bytesNonObjptrs + (numObjptrs * OBJPTR_SIZE);
skip = 0;
} else if (ARRAY_TAG == tag) {
headerBytes = GC_ARRAY_HEADER_SIZE;
objectBytes = sizeofArrayNoHeader (s, getArrayLength (p),
bytesNonObjptrs, numObjptrs);
skip = 0;
} else { /* Stack. */
bool current;
size_t reservedNew;
GC_stack stack;
assert (STACK_TAG == tag);
headerBytes = GC_STACK_HEADER_SIZE;
stack = (GC_stack)p;
current = getStackCurrent(s) == stack;
reservedNew = sizeofStackShrinkReserved (s, stack, current);
if (reservedNew < stack->reserved) {
if (DEBUG_STACKS or s->controls.messages)
fprintf (stderr,
"[GC: Shrinking stack of size %s bytes to size %s bytes, using %s bytes.]\n",
uintmaxToCommaString(stack->reserved),
uintmaxToCommaString(reservedNew),
uintmaxToCommaString(stack->used));
stack->reserved = reservedNew;
}
objectBytes = sizeof (struct GC_stack) + stack->used;
skip = stack->reserved - stack->used;
}
size = headerBytes + objectBytes;
assert (s->forwardState.back + size + skip <= s->forwardState.toLimit);
/* Copy the object. */
GC_memcpy (p - headerBytes, s->forwardState.back, size);
/* If the object has a valid weak pointer, link it into the weaks
* for update after the copying GC is done.
*/
if ((WEAK_TAG == tag) and (numObjptrs == 1)) {
GC_weak w;
w = (GC_weak)(s->forwardState.back + GC_NORMAL_HEADER_SIZE + offsetofWeak (s));
if (DEBUG_WEAK)
fprintf (stderr, "forwarding weak "FMTPTR" ",
(uintptr_t)w);
if (isObjptr (w->objptr)
and (not s->forwardState.amInMinorGC
or isObjptrInNursery (s, w->objptr))) {
if (DEBUG_WEAK)
fprintf (stderr, "linking\n");
w->link = s->weaks;
s->weaks = w;
} else {
if (DEBUG_WEAK)
fprintf (stderr, "not linking\n");
}
}
/* Store the forwarding pointer in the old object. */
*((GC_header*)(p - GC_HEADER_SIZE)) = GC_FORWARDED;
*((objptr*)p) = pointerToObjptr (s->forwardState.back + headerBytes,
s->forwardState.toStart);
/* Update the back of the queue. */
s->forwardState.back += size + skip;
assert (isAligned ((size_t)s->forwardState.back + GC_NORMAL_HEADER_SIZE,
s->alignment));
}
*opp = *((objptr*)p);
if (DEBUG_DETAILED)
fprintf (stderr,
"forwardObjptr --> *opp = "FMTPTR"\n",
(uintptr_t)*opp);
assert (isObjptrInToSpace (s, *opp));
}
void forwardObjptrIfInNursery (GC_state s, objptr *opp) {
objptr op;
pointer p;
op = *opp;
p = objptrToPointer (op, s->heap.start);
if (p < s->heap.nursery)
return;
if (DEBUG_GENERATIONAL)
fprintf (stderr,
"forwardObjptrIfInNursery opp = "FMTPTR" op = "FMTOBJPTR" p = "FMTPTR"\n",
(uintptr_t)opp, op, (uintptr_t)p);
assert (s->heap.nursery <= p and p < s->limitPlusSlop);
forwardObjptr (s, opp);
}
/* Walk through all the cards and forward all intergenerational pointers. */
void forwardInterGenerationalObjptrs (GC_state s) {
GC_cardMapElem *cardMap;
GC_crossMapElem *crossMap;
pointer oldGenStart, oldGenEnd;
size_t cardIndex, maxCardIndex;
pointer cardStart, cardEnd;
pointer objectStart;
if (DEBUG_GENERATIONAL)
fprintf (stderr, "Forwarding inter-generational pointers.\n");
updateCrossMap (s);
/* Constants. */
cardMap = s->generationalMaps.cardMap;
crossMap = s->generationalMaps.crossMap;
maxCardIndex = sizeToCardMapIndex (align (s->heap.oldGenSize, CARD_SIZE));
oldGenStart = s->heap.start;
oldGenEnd = oldGenStart + s->heap.oldGenSize;
/* Loop variables*/
objectStart = alignFrontier (s, s->heap.start);
cardIndex = 0;
cardStart = oldGenStart;
checkAll:
assert (cardIndex <= maxCardIndex);
assert (isFrontierAligned (s, objectStart));
if (cardIndex == maxCardIndex)
goto done;
checkCard:
if (DEBUG_GENERATIONAL)
fprintf (stderr, "checking card %"PRIuMAX" objectStart = "FMTPTR"\n",
(uintmax_t)cardIndex, (uintptr_t)objectStart);
assert (objectStart < oldGenStart + cardMapIndexToSize (cardIndex + 1));
if (cardMap[cardIndex]) {
pointer lastObject;
s->cumulativeStatistics.numCardsMarked++;
if (DEBUG_GENERATIONAL)
fprintf (stderr, "card %"PRIuMAX" is marked objectStart = "FMTPTR"\n",
(uintmax_t)cardIndex, (uintptr_t)objectStart);
assert (isFrontierAligned (s, objectStart));
cardEnd = cardStart + CARD_SIZE;
if (oldGenEnd < cardEnd)
cardEnd = oldGenEnd;
assert (objectStart < cardEnd);
lastObject = objectStart;
/* If we ever add Weak.set, then there could be intergenerational
* weak pointers, in which case we would need to link the weak
* objects into s->weaks. But for now, since there is no
* Weak.set, the foreachObjptrInRange will do the right thing on
* weaks, since the weak pointer will never be into the nursery.
*/
objectStart = foreachObjptrInRange (s, objectStart, &cardEnd,
forwardObjptrIfInNursery, FALSE);
s->cumulativeStatistics.bytesScannedMinor += (uintmax_t)(objectStart - lastObject);
if (objectStart == oldGenEnd)
goto done;
cardIndex = sizeToCardMapIndex ((size_t)(objectStart - oldGenStart));
cardStart = oldGenStart + cardMapIndexToSize (cardIndex);
goto checkCard;
} else {
unless (CROSS_MAP_EMPTY == crossMap[cardIndex])
objectStart = cardStart + (size_t)(crossMap[cardIndex] * CROSS_MAP_OFFSET_SCALE);
if (DEBUG_GENERATIONAL)
fprintf (stderr,
"card %"PRIuMAX" is not marked"
" crossMap[%"PRIuMAX"] == %"PRIuMAX""
" objectStart = "FMTPTR"\n",
(uintmax_t)cardIndex, (uintmax_t)cardIndex,
(uintmax_t)(crossMap[cardIndex] * CROSS_MAP_OFFSET_SCALE),
(uintptr_t)objectStart);
cardIndex++;
cardStart += CARD_SIZE;
goto checkAll;
}
assert (FALSE);
done:
if (DEBUG_GENERATIONAL)
fprintf (stderr, "Forwarding inter-generational pointers done.\n");
}
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