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authorwolfbeast <mcwerewolf@gmail.com>2018-02-03 19:02:06 +0100
committerwolfbeast <mcwerewolf@gmail.com>2018-02-03 19:03:05 +0100
commit10494e1b7d0b3cd945bb76dca10f5637cf786f27 (patch)
tree8a6487e386c06e7dfe63f2a4f2ffe5b589c59f60 /js/src/gc/Verifier.cpp
parent559933a9a58f96ac62ad0f60602f45344581604f (diff)
parente27da6cc5e825b58f810b368b2bd59bca2164ab0 (diff)
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Merge branch 'ported-moebius'
Remove GCZeal code from Spidermonkey. This resolves #8
Diffstat (limited to 'js/src/gc/Verifier.cpp')
-rw-r--r--js/src/gc/Verifier.cpp414
1 files changed, 0 insertions, 414 deletions
diff --git a/js/src/gc/Verifier.cpp b/js/src/gc/Verifier.cpp
index dd4031606..3ebbbb4f6 100644
--- a/js/src/gc/Verifier.cpp
+++ b/js/src/gc/Verifier.cpp
@@ -26,420 +26,6 @@
using namespace js;
using namespace js::gc;
-#ifdef JS_GC_ZEAL
-
-/*
- * Write barrier verification
- *
- * The next few functions are for write barrier verification.
- *
- * The VerifyBarriers function is a shorthand. It checks if a verification phase
- * is currently running. If not, it starts one. Otherwise, it ends the current
- * phase and starts a new one.
- *
- * The user can adjust the frequency of verifications, which causes
- * VerifyBarriers to be a no-op all but one out of N calls. However, if the
- * |always| parameter is true, it starts a new phase no matter what.
- *
- * Pre-Barrier Verifier:
- * When StartVerifyBarriers is called, a snapshot is taken of all objects in
- * the GC heap and saved in an explicit graph data structure. Later,
- * EndVerifyBarriers traverses the heap again. Any pointer values that were in
- * the snapshot and are no longer found must be marked; otherwise an assertion
- * triggers. Note that we must not GC in between starting and finishing a
- * verification phase.
- */
-
-struct EdgeValue
-{
- void* thing;
- JS::TraceKind kind;
- const char* label;
-};
-
-struct VerifyNode
-{
- void* thing;
- JS::TraceKind kind;
- uint32_t count;
- EdgeValue edges[1];
-};
-
-typedef HashMap<void*, VerifyNode*, DefaultHasher<void*>, SystemAllocPolicy> NodeMap;
-
-/*
- * The verifier data structures are simple. The entire graph is stored in a
- * single block of memory. At the beginning is a VerifyNode for the root
- * node. It is followed by a sequence of EdgeValues--the exact number is given
- * in the node. After the edges come more nodes and their edges.
- *
- * The edgeptr and term fields are used to allocate out of the block of memory
- * for the graph. If we run out of memory (i.e., if edgeptr goes beyond term),
- * we just abandon the verification.
- *
- * The nodemap field is a hashtable that maps from the address of the GC thing
- * to the VerifyNode that represents it.
- */
-class js::VerifyPreTracer final : public JS::CallbackTracer
-{
- JS::AutoDisableGenerationalGC noggc;
-
- void onChild(const JS::GCCellPtr& thing) override;
-
- public:
- /* The gcNumber when the verification began. */
- uint64_t number;
-
- /* This counts up to gcZealFrequency to decide whether to verify. */
- int count;
-
- /* This graph represents the initial GC "snapshot". */
- VerifyNode* curnode;
- VerifyNode* root;
- char* edgeptr;
- char* term;
- NodeMap nodemap;
-
- explicit VerifyPreTracer(JSRuntime* rt)
- : JS::CallbackTracer(rt), noggc(rt), number(rt->gc.gcNumber()), count(0), curnode(nullptr),
- root(nullptr), edgeptr(nullptr), term(nullptr)
- {}
-
- ~VerifyPreTracer() {
- js_free(root);
- }
-};
-
-/*
- * This function builds up the heap snapshot by adding edges to the current
- * node.
- */
-void
-VerifyPreTracer::onChild(const JS::GCCellPtr& thing)
-{
- MOZ_ASSERT(!IsInsideNursery(thing.asCell()));
-
- // Skip things in other runtimes.
- if (thing.asCell()->asTenured().runtimeFromAnyThread() != runtime())
- return;
-
- edgeptr += sizeof(EdgeValue);
- if (edgeptr >= term) {
- edgeptr = term;
- return;
- }
-
- VerifyNode* node = curnode;
- uint32_t i = node->count;
-
- node->edges[i].thing = thing.asCell();
- node->edges[i].kind = thing.kind();
- node->edges[i].label = contextName();
- node->count++;
-}
-
-static VerifyNode*
-MakeNode(VerifyPreTracer* trc, void* thing, JS::TraceKind kind)
-{
- NodeMap::AddPtr p = trc->nodemap.lookupForAdd(thing);
- if (!p) {
- VerifyNode* node = (VerifyNode*)trc->edgeptr;
- trc->edgeptr += sizeof(VerifyNode) - sizeof(EdgeValue);
- if (trc->edgeptr >= trc->term) {
- trc->edgeptr = trc->term;
- return nullptr;
- }
-
- node->thing = thing;
- node->count = 0;
- node->kind = kind;
- if (!trc->nodemap.add(p, thing, node)) {
- trc->edgeptr = trc->term;
- return nullptr;
- }
-
- return node;
- }
- return nullptr;
-}
-
-static VerifyNode*
-NextNode(VerifyNode* node)
-{
- if (node->count == 0)
- return (VerifyNode*)((char*)node + sizeof(VerifyNode) - sizeof(EdgeValue));
- else
- return (VerifyNode*)((char*)node + sizeof(VerifyNode) +
- sizeof(EdgeValue)*(node->count - 1));
-}
-
-void
-gc::GCRuntime::startVerifyPreBarriers()
-{
- if (verifyPreData || isIncrementalGCInProgress())
- return;
-
- if (IsIncrementalGCUnsafe(rt) != AbortReason::None)
- return;
-
- number++;
-
- VerifyPreTracer* trc = js_new<VerifyPreTracer>(rt);
- if (!trc)
- return;
-
- AutoPrepareForTracing prep(rt->contextFromMainThread(), WithAtoms);
-
- for (auto chunk = allNonEmptyChunks(); !chunk.done(); chunk.next())
- chunk->bitmap.clear();
-
- gcstats::AutoPhase ap(stats, gcstats::PHASE_TRACE_HEAP);
-
- const size_t size = 64 * 1024 * 1024;
- trc->root = (VerifyNode*)js_malloc(size);
- if (!trc->root)
- goto oom;
- trc->edgeptr = (char*)trc->root;
- trc->term = trc->edgeptr + size;
-
- if (!trc->nodemap.init())
- goto oom;
-
- /* Create the root node. */
- trc->curnode = MakeNode(trc, nullptr, JS::TraceKind(0));
-
- incrementalState = State::MarkRoots;
-
- /* Make all the roots be edges emanating from the root node. */
- traceRuntime(trc, prep.session().lock);
-
- VerifyNode* node;
- node = trc->curnode;
- if (trc->edgeptr == trc->term)
- goto oom;
-
- /* For each edge, make a node for it if one doesn't already exist. */
- while ((char*)node < trc->edgeptr) {
- for (uint32_t i = 0; i < node->count; i++) {
- EdgeValue& e = node->edges[i];
- VerifyNode* child = MakeNode(trc, e.thing, e.kind);
- if (child) {
- trc->curnode = child;
- js::TraceChildren(trc, e.thing, e.kind);
- }
- if (trc->edgeptr == trc->term)
- goto oom;
- }
-
- node = NextNode(node);
- }
-
- verifyPreData = trc;
- incrementalState = State::Mark;
- marker.start();
-
- for (ZonesIter zone(rt, WithAtoms); !zone.done(); zone.next()) {
- PurgeJITCaches(zone);
- if (!zone->usedByExclusiveThread) {
- zone->setNeedsIncrementalBarrier(true, Zone::UpdateJit);
- zone->arenas.purge();
- }
- }
-
- return;
-
-oom:
- incrementalState = State::NotActive;
- js_delete(trc);
- verifyPreData = nullptr;
-}
-
-static bool
-IsMarkedOrAllocated(TenuredCell* cell)
-{
- return cell->isMarked() || cell->arena()->allocatedDuringIncremental;
-}
-
-struct CheckEdgeTracer : public JS::CallbackTracer {
- VerifyNode* node;
- explicit CheckEdgeTracer(JSRuntime* rt) : JS::CallbackTracer(rt), node(nullptr) {}
- void onChild(const JS::GCCellPtr& thing) override;
-};
-
-static const uint32_t MAX_VERIFIER_EDGES = 1000;
-
-/*
- * This function is called by EndVerifyBarriers for every heap edge. If the edge
- * already existed in the original snapshot, we "cancel it out" by overwriting
- * it with nullptr. EndVerifyBarriers later asserts that the remaining
- * non-nullptr edges (i.e., the ones from the original snapshot that must have
- * been modified) must point to marked objects.
- */
-void
-CheckEdgeTracer::onChild(const JS::GCCellPtr& thing)
-{
- // Skip things in other runtimes.
- if (thing.asCell()->asTenured().runtimeFromAnyThread() != runtime())
- return;
-
- /* Avoid n^2 behavior. */
- if (node->count > MAX_VERIFIER_EDGES)
- return;
-
- for (uint32_t i = 0; i < node->count; i++) {
- if (node->edges[i].thing == thing.asCell()) {
- MOZ_ASSERT(node->edges[i].kind == thing.kind());
- node->edges[i].thing = nullptr;
- return;
- }
- }
-}
-
-void
-js::gc::AssertSafeToSkipBarrier(TenuredCell* thing)
-{
- Zone* zone = thing->zoneFromAnyThread();
- MOZ_ASSERT(!zone->needsIncrementalBarrier() || zone->isAtomsZone());
-}
-
-static bool
-IsMarkedOrAllocated(const EdgeValue& edge)
-{
- if (!edge.thing || IsMarkedOrAllocated(TenuredCell::fromPointer(edge.thing)))
- return true;
-
- // Permanent atoms and well-known symbols aren't marked during graph traversal.
- if (edge.kind == JS::TraceKind::String && static_cast<JSString*>(edge.thing)->isPermanentAtom())
- return true;
- if (edge.kind == JS::TraceKind::Symbol && static_cast<JS::Symbol*>(edge.thing)->isWellKnownSymbol())
- return true;
-
- return false;
-}
-
-void
-gc::GCRuntime::endVerifyPreBarriers()
-{
- VerifyPreTracer* trc = verifyPreData;
-
- if (!trc)
- return;
-
- MOZ_ASSERT(!JS::IsGenerationalGCEnabled(rt));
-
- AutoPrepareForTracing prep(rt->contextFromMainThread(), SkipAtoms);
-
- bool compartmentCreated = false;
-
- /* We need to disable barriers before tracing, which may invoke barriers. */
- for (ZonesIter zone(rt, WithAtoms); !zone.done(); zone.next()) {
- if (!zone->needsIncrementalBarrier())
- compartmentCreated = true;
-
- zone->setNeedsIncrementalBarrier(false, Zone::UpdateJit);
- PurgeJITCaches(zone);
- }
-
- /*
- * We need to bump gcNumber so that the methodjit knows that jitcode has
- * been discarded.
- */
- MOZ_ASSERT(trc->number == number);
- number++;
-
- verifyPreData = nullptr;
- incrementalState = State::NotActive;
-
- if (!compartmentCreated && IsIncrementalGCUnsafe(rt) == AbortReason::None) {
- CheckEdgeTracer cetrc(rt);
-
- /* Start after the roots. */
- VerifyNode* node = NextNode(trc->root);
- while ((char*)node < trc->edgeptr) {
- cetrc.node = node;
- js::TraceChildren(&cetrc, node->thing, node->kind);
-
- if (node->count <= MAX_VERIFIER_EDGES) {
- for (uint32_t i = 0; i < node->count; i++) {
- EdgeValue& edge = node->edges[i];
- if (!IsMarkedOrAllocated(edge)) {
- char msgbuf[1024];
- SprintfLiteral(msgbuf,
- "[barrier verifier] Unmarked edge: %s %p '%s' edge to %s %p",
- JS::GCTraceKindToAscii(node->kind), node->thing,
- edge.label,
- JS::GCTraceKindToAscii(edge.kind), edge.thing);
- MOZ_ReportAssertionFailure(msgbuf, __FILE__, __LINE__);
- MOZ_CRASH();
- }
- }
- }
-
- node = NextNode(node);
- }
- }
-
- marker.reset();
- marker.stop();
-
- js_delete(trc);
-}
-
-/*** Barrier Verifier Scheduling ***/
-
-void
-gc::GCRuntime::verifyPreBarriers()
-{
- if (verifyPreData)
- endVerifyPreBarriers();
- else
- startVerifyPreBarriers();
-}
-
-void
-gc::VerifyBarriers(JSRuntime* rt, VerifierType type)
-{
- if (type == PreBarrierVerifier)
- rt->gc.verifyPreBarriers();
-}
-
-void
-gc::GCRuntime::maybeVerifyPreBarriers(bool always)
-{
- if (!hasZealMode(ZealMode::VerifierPre))
- return;
-
- if (rt->mainThread.suppressGC)
- return;
-
- if (verifyPreData) {
- if (++verifyPreData->count < zealFrequency && !always)
- return;
-
- endVerifyPreBarriers();
- }
-
- startVerifyPreBarriers();
-}
-
-void
-js::gc::MaybeVerifyBarriers(JSContext* cx, bool always)
-{
- GCRuntime* gc = &cx->runtime()->gc;
- gc->maybeVerifyPreBarriers(always);
-}
-
-void
-js::gc::GCRuntime::finishVerifier()
-{
- if (verifyPreData) {
- js_delete(verifyPreData);
- verifyPreData = nullptr;
- }
-}
-
-#endif /* JS_GC_ZEAL */
-
#ifdef JSGC_HASH_TABLE_CHECKS
class CheckHeapTracer : public JS::CallbackTracer