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/* ScummVM - Graphic Adventure Engine
*
* ScummVM is the legal property of its developers, whose names
* are too numerous to list here. Please refer to the COPYRIGHT
* file distributed with this source distribution.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
* $URL$
* $Id$
*
*/
#include "sci/engine/gc.h"
#include "common/array.h"
namespace Sci {
//#define GC_DEBUG_CODE
struct WorklistManager {
Common::Array<reg_t> _worklist;
AddrSet _map;
void push(reg_t reg) {
if (!reg.segment) // No numbers
return;
debugC(2, kDebugLevelGC, "[GC] Adding %04x:%04x", PRINT_REG(reg));
if (_map.contains(reg))
return; // already dealt with it
_map.setVal(reg, true);
_worklist.push_back(reg);
}
void pushArray(const Common::Array<reg_t> &tmp) {
for (Common::Array<reg_t>::const_iterator it = tmp.begin(); it != tmp.end(); ++it)
push(*it);
}
};
static AddrSet *normalizeAddresses(SegManager *segMan, const AddrSet &nonnormal_map) {
AddrSet *normal_map = new AddrSet();
for (AddrSet::const_iterator i = nonnormal_map.begin(); i != nonnormal_map.end(); ++i) {
reg_t reg = i->_key;
SegmentObj *mobj = segMan->getSegmentObj(reg.segment);
if (mobj) {
reg = mobj->findCanonicAddress(segMan, reg);
normal_map->setVal(reg, true);
}
}
return normal_map;
}
AddrSet *findAllActiveReferences(EngineState *s) {
SegManager *segMan = s->_segMan;
AddrSet *normal_map = NULL;
WorklistManager wm;
uint i;
assert(!s->_executionStack.empty());
// Initialise
// Init: Registers
wm.push(s->r_acc);
wm.push(s->r_prev);
// Init: Value Stack
// We do this one by hand since the stack doesn't know the current execution stack
Common::List<ExecStack>::iterator iter = s->_executionStack.reverse_begin();
// Skip fake kernel stack frame if it's on top
if (((*iter).type == EXEC_STACK_TYPE_KERNEL))
--iter;
assert((iter != s->_executionStack.end()) && ((*iter).type != EXEC_STACK_TYPE_KERNEL));
ExecStack &xs = *iter;
reg_t *pos;
for (pos = s->stack_base; pos < xs.sp; pos++)
wm.push(*pos);
debugC(2, kDebugLevelGC, "[GC] -- Finished adding value stack");
// Init: Execution Stack
for (iter = s->_executionStack.begin();
iter != s->_executionStack.end(); ++iter) {
ExecStack &es = *iter;
if (es.type != EXEC_STACK_TYPE_KERNEL) {
wm.push(es.objp);
wm.push(es.sendp);
if (es.type == EXEC_STACK_TYPE_VARSELECTOR)
wm.push(*(es.getVarPointer(s->_segMan)));
}
}
debugC(2, kDebugLevelGC, "[GC] -- Finished adding execution stack");
const Common::Array<SegmentObj *> &heap = segMan->getSegments();
// Init: Explicitly loaded scripts
for (i = 1; i < heap.size(); i++) {
if (heap[i] && heap[i]->getType() == SEG_TYPE_SCRIPT) {
Script *script = (Script *)heap[i];
if (script->getLockers()) { // Explicitly loaded?
wm.pushArray(script->listObjectReferences());
}
}
}
debugC(2, kDebugLevelGC, "[GC] -- Finished explicitly loaded scripts, done with root set");
// Run Worklist Algorithm
SegmentId stack_seg = segMan->findSegmentByType(SEG_TYPE_STACK);
while (!wm._worklist.empty()) {
reg_t reg = wm._worklist.back();
wm._worklist.pop_back();
if (reg.segment != stack_seg) { // No need to repeat this one
debugC(2, kDebugLevelGC, "[GC] Checking %04x:%04x", PRINT_REG(reg));
if (reg.segment < heap.size() && heap[reg.segment]) {
// Valid heap object? Find its outgoing references!
wm.pushArray(heap[reg.segment]->listAllOutgoingReferences(reg));
}
}
}
// Normalise
normal_map = normalizeAddresses(segMan, wm._map);
return normal_map;
}
void run_gc(EngineState *s) {
SegManager *segMan = s->_segMan;
// Some debug stuff
debugC(2, kDebugLevelGC, "[GC] Running...");
#ifdef GC_DEBUG_CODE
const char *segnames[SEG_TYPE_MAX + 1];
int segcount[SEG_TYPE_MAX + 1];
memset(segnames, 0, sizeof(segnames));
memset(segcount, 0, sizeof(segcount));
#endif
// Compute the set of all segments references currently in use.
AddrSet *activeRefs = findAllActiveReferences(s);
// Iterate over all segments, and check for each whether it
// contains stuff that can be collected.
const Common::Array<SegmentObj *> &heap = segMan->getSegments();
for (uint seg = 1; seg < heap.size(); seg++) {
SegmentObj *mobj = heap[seg];
if (mobj != NULL) {
#ifdef GC_DEBUG_CODE
const SegmentType type = mobj->getType();
segnames[type] = SegmentObj::getSegmentTypeName(type);
#endif
// Get a list of all deallocatable objects in this segment,
// then free any which are not referenced from somewhere.
const Common::Array<reg_t> tmp = mobj->listAllDeallocatable(seg);
for (Common::Array<reg_t>::const_iterator it = tmp.begin(); it != tmp.end(); ++it) {
const reg_t addr = *it;
if (!activeRefs->contains(addr)) {
// Not found -> we can free it
mobj->freeAtAddress(segMan, addr);
debugC(2, kDebugLevelGC, "[GC] Deallocating %04x:%04x", PRINT_REG(addr));
#ifdef GC_DEBUG_CODE
segcount[type]++;
#endif
}
}
}
}
delete activeRefs;
#ifdef GC_DEBUG_CODE
// Output debug summary of garbage collection
debugC(2, kDebugLevelGC, "[GC] Summary:");
for (int i = 0; i <= SEG_TYPE_MAX; i++)
if (segcount[i])
debugC(2, kDebugLevelGC, "\t%d\t* %s", segcount[i], segnames[i]);
#endif
}
} // End of namespace Sci
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