build sorted vectors for large/huge objects at gc time, and use binarySearch...

build sorted vectors for large/huge objects at gc time, and use binarySearch to power ::allocationFrom

src/gc/collector.cpp

@@ -438,6 +438,8 @@ void runCollection() {
 
     Timer _t("collecting", /*min_usec=*/10000);
 
+    global_heap.prepareForCollection();
+
     markPhase();
 
     // The sweep phase will not free weakly-referenced objects, so that we can inspect their
@@ -500,6 +502,8 @@ void runCollection() {
         }
     }
 
+    global_heap.cleanupAfterCollection();
+
     if (VERBOSITY("gc") >= 2)
         printf("Collection #%d done\n\n", ncollections);
 

src/gc/heap.cpp

@@ -661,7 +661,23 @@ void LargeArena::free(GCAllocation* al) {
     _freeLargeObj(LargeObj::fromAllocation(al));
 }
 
+struct CompareObjLookupCache {
+    int operator()(const void* p, const ObjLookupCache& obj) {
+        if (p < (char*)obj.data)
+            return -1;
+        if (p >= (char*)obj.data + obj.size)
+            return 1;
+        return 0;
+    }
+};
+
 GCAllocation* LargeArena::allocationFrom(void* ptr) {
+    if (lookup.size()) {
+        int idx = binarySearch(ptr, lookup.begin(), lookup.end(), CompareObjLookupCache());
+        if (idx < 0)
+            return NULL;
+        return (GCAllocation*)lookup[idx].data;
+    } else {
         LargeObj* obj = NULL;
 
         for (obj = head; obj; obj = obj->next) {
@@ -672,6 +688,19 @@ GCAllocation* LargeArena::allocationFrom(void* ptr) {
             }
         }
         return NULL;
+    }
+}
+
+void LargeArena::prepareForCollection() {
+    for (LargeObj* lo = head; lo; lo = lo->next) {
+        lookup.push_back(ObjLookupCache(lo, &lo->data[0], lo->size));
+    }
+    std::sort(lookup.begin(), lookup.end(),
+              [](const ObjLookupCache& lo1, const ObjLookupCache& lo2) { return lo1.data < lo2.data; });
+}
+
+void LargeArena::cleanupAfterCollection() {
+    lookup.clear();
 }
 
 void LargeArena::freeUnmarked(std::vector<Box*>& weakly_referenced, std::vector<BoxedClass*>& classes_to_free) {
@@ -682,7 +711,6 @@ void LargeArena::getStatistics(HeapStatistics* stats) {
     forEach(head, [stats](LargeObj* obj) { addStatistic(stats, obj->data, obj->size); });
 }
 
-
 void LargeArena::add_free_chunk(LargeFreeChunk* free_chunks, size_t size) {
     size_t num_chunks = size >> CHUNK_BITS;
 
@@ -831,7 +859,7 @@ GCAllocation* HugeArena::alloc(size_t size) {
     total_size = (total_size + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);
     extendMapping(total_size);
     HugeObj* rtn = (HugeObj*)allocFromArena(total_size);
-    rtn->obj_size = size;
+    rtn->size = size;
 
     nullNextPrev(rtn);
     insertIntoLL(&head, rtn);
@@ -847,7 +875,7 @@ GCAllocation* HugeArena::realloc(GCAllocation* al, size_t bytes) {
         return al;
 
     GCAllocation* rtn = heap->alloc(bytes);
-    memcpy(rtn, al, std::min(bytes, obj->obj_size));
+    memcpy(rtn, al, std::min(bytes, obj->size));
 
     _freeHugeObj(obj);
     return rtn;
@@ -858,13 +886,32 @@ void HugeArena::free(GCAllocation* al) {
 }
 
 GCAllocation* HugeArena::allocationFrom(void* ptr) {
+    if (lookup.size()) {
+        int idx = binarySearch(ptr, lookup.begin(), lookup.end(), CompareObjLookupCache());
+        if (idx < 0)
+            return NULL;
+        return (GCAllocation*)lookup[idx].data;
+    } else {
         HugeObj* cur = head;
         while (cur) {
-        if (ptr >= cur && ptr < &cur->data[cur->obj_size])
+            if (ptr >= cur && ptr < &cur->data[cur->size])
                 return &cur->data[0];
             cur = cur->next;
         }
         return NULL;
+    }
+}
+
+void HugeArena::prepareForCollection() {
+    for (HugeObj* lo = head; lo; lo = lo->next) {
+        lookup.push_back(ObjLookupCache(lo, &lo->data[0], lo->size));
+    }
+    std::sort(lookup.begin(), lookup.end(),
+              [](const ObjLookupCache& lo1, const ObjLookupCache& lo2) { return lo1.data < lo2.data; });
+}
+
+void HugeArena::cleanupAfterCollection() {
+    lookup.clear();
 }
 
 void HugeArena::freeUnmarked(std::vector<Box*>& weakly_referenced, std::vector<BoxedClass*>& classes_to_free) {

src/gc/heap.h

@@ -227,6 +227,9 @@ public:
 
     void getStatistics(HeapStatistics* stats);
 
+    void prepareForCollection() {}
+    void cleanupAfterCollection() {}
+
 private:
     template <int N> class Bitmap {
         static_assert(N % 64 == 0, "");
@@ -361,6 +364,15 @@ private:
     GCAllocation* __attribute__((__malloc__)) _alloc(size_t bytes, int bucket_idx);
 };
 
+struct ObjLookupCache {
+    void* objptr;
+    void* data;
+    size_t size;
+
+    ObjLookupCache(void* objptr, void* data, size_t size) : objptr(objptr), data(data), size(size) {}
+};
+
+
 //
 // The LargeArena allocates objects where 3584 < size <1024*1024-CHUNK_SIZE-sizeof(LargeObject) bytes.
 //
@@ -407,6 +419,7 @@ private:
 
     static constexpr int NUM_FREE_LISTS = 32;
 
+    std::vector<ObjLookupCache> lookup; // used during gc's to speed up finding large object GCAllocations
     Heap* heap;
     LargeObj* head;
     LargeBlock* blocks;
@@ -431,6 +444,9 @@ public:
     void freeUnmarked(std::vector<Box*>& weakly_referenced, std::vector<BoxedClass*>& classes_to_free);
 
     void getStatistics(HeapStatistics* stats);
+
+    void prepareForCollection();
+    void cleanupAfterCollection();
 };
 
 // The HugeArena allocates objects where size > 1024*1024 bytes.
@@ -450,14 +466,17 @@ public:
 
     void getStatistics(HeapStatistics* stats);
 
+    void prepareForCollection();
+    void cleanupAfterCollection();
+
 private:
     struct HugeObj {
         HugeObj* next, **prev;
-        size_t obj_size;
+        size_t size;
         GCAllocation data[0];
 
         int mmap_size() {
-            size_t total_size = obj_size + sizeof(HugeObj);
+            size_t total_size = size + sizeof(HugeObj);
             total_size = (total_size + PAGE_SIZE - 1) & ~(PAGE_SIZE - 1);
             return total_size;
         }
@@ -474,6 +493,7 @@ private:
     void _freeHugeObj(HugeObj* lobj);
 
     HugeObj* head;
+    std::vector<ObjLookupCache> lookup; // used during gc's to speed up finding large object GCAllocations
 
     Heap* heap;
 };
@@ -552,6 +572,18 @@ public:
         huge_arena.freeUnmarked(weakly_referenced, classes_to_free);
     }
 
+    void prepareForCollection() {
+        small_arena.prepareForCollection();
+        large_arena.prepareForCollection();
+        huge_arena.prepareForCollection();
+    }
+
+    void cleanupAfterCollection() {
+        small_arena.cleanupAfterCollection();
+        large_arena.cleanupAfterCollection();
+        huge_arena.cleanupAfterCollection();
+    }
+
     void dumpHeapStatistics(int level);
 
 private: